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XyZspineZyX
10-03-2003, 10:58 AM
No Text

Message Edited on 10/03/0312:02PM by Vo101_Isegrim

XyZspineZyX
10-03-2003, 10:58 AM
No Text

Message Edited on 10/03/0312:02PM by Vo101_Isegrim

XyZspineZyX
10-03-2003, 11:01 AM
From :

"Measurements of the flying qualities of a Supermarine Sptitife VA airplane." NACA Advanced Confidental Report, by William H. Phillips and Joseph R. Vensel.

The tests were conducted at Langley field, Va., during the period from December 30, 1941 to January 29, 1942. Sixteen flights and apprx. 18 hours flying time were required to complete the tests.

[...]

Desription of the the Supermarine Spitfire airplane

Name and Type : Supermarine Spitfire VA (Air Mininstry No. W3119).
Engine : R-R Merlin XLV
Weight, empty : 4960 lbs
Normal gross weight : 6237 lbs
Weight as flown for tests : 6184 lbs

Ailerons (metal-covered)
Lenght (each) : 6 feet, 10 1/2 inches
Area (total area, each) : 9.45 sq. feet
Balance area (each) : 2.45 square feet

[...]

A stick force of 2 lbs to the right and 3 lbs to the left was required to overcome aileron friction.

[...]

Lateral Stability and Control

Aileron-control characteristics : The effectiveness of the ailerons of the Supermarine Spitfire airplane was determined by recording the rolling velocity produced by abrubtly deflecting the ailerons at various speeds. The aileron angles and stick forces were measured. It should be noted that the airplane tested was equipeed with metal covered ailerons.

[...]

The ailerons were sufficiently effective at low speeds, and were relatively light at small deflections in high speed flight. The forces required to obtain high rolling velocities in high-speed flight were considered excessive.
With a stick force of 30 lbs, full deflection of the ailerons could be obtained at speeds lower than 110 miles per hour. A value of pb/2V of 0.09 radian in left rolls and 0.08 radian in right rolls were obtained with full deflection.

Rolling velocity (at 6000 ft altitude) of about 59 degrees per second could be obtained with 30 lbs stick force at 230 miles per hour indicated speed.

The ailerons were relatively light for small deflections, but the slope of the curve of stick force against deflection increased progressively with deflection, so that about five times as much force was required to fully deflect the ailerons as was needed to reach one-half of the maximum travel. The effectiveness of the ailerons increased almost linearly with deflection all the way up to maximum position. The value of pb/2V obtained for a given ailerons deflection was nearly the same in speeds and conditions tested. It may be concluded, therefore, that there was very little reduction in aileron effectiveness either by separation of flow near minimum speeds or by wing twist at high speed.

Fig 27 shows the aileron deflection, stick force, and helix angle obtained in a series of roll at various speeds intended to represent the maximum rolling velocity that could be readily obtained.

The pilot was able to exert a maximum of about 40 lbs on the stick. With this force, full deflection could be attained only up to about 130 miles per hour. Beyond this speed, the rapid increase in stick force near maximum deflection prevented full motion of the control stick. Only one-half of the available deflection was reached with a 40 lbs stick force at 300 miles per hour, with the result that the pb/2V obtainable at this speed was reduced to 0.04 radian, or one-half that reached at low speeds.

Another method of presenting the results of the aileron-roll measurements is that given in figure 28, where the force for different rolling velocities is plotted as a function of speed. The relatively light forces required to reach small rolling velocities are readily seen from this figure. The excessive forces required to reach high rolling velocities and the impossibility of obtaining maximum aileron deflection much above 140 miles per hour are also illustrated.


From :

STABILITY AND CONTROL SUB-COMMITEE. AERONAUTICAL RESEARCH COMMITEE
Comparision of aileron control charactheristics as determined in Flight Tests of P-36, P-40, 'Spitfire' and 'Hurricane' Pursuit airplanes.

By William H. Philps. N.A.C.A. Confidental Bulletin. 16th November, 1942

[..]

The aileron effectiveness of the various airplanes is compared in the following table on the basis of the response obtained with stick forces of 30 and 5 pounds. A force of 30 lbs is somewhat less than the greatest stick force exerted by the pilot. Repeated flight measurements have shown, however, that this forcer is a reasonable upper limit for manouvering at high speeds. A comparision at a stick force of 5 lbs are also included to bring out a rather interesting fact regarding the order of merit of aileron effectiveness for the various airplanes when very light forces are used :

Rolling velocities obtained with 30 lbs stick force at 230 mph indicated airspeed at 10 000 ft. (deg/sec)

P-36 : 43
P-40 : 90
Hurricane : 64
Spitfire : 63

Rolling velocities obtained with 5 lbs stick force at 230 mph indicated airspeed at 10 000 ft (deg/sec)

P-36 : 9
P-40 : 8
Hurricane : 19
Spitfire : 15



A further comparision of the aileron performance of the four airplanes is given in figure 2, which shows how the control force characteristics influence the rolling velocities obtained through the speed range.


http://www.x-plane.org/users/isegrim/ROLLRATE%20Spit%20Hurri%20P40%20P36.jpg





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Vezérünk a Bátorság, K*sérµnk a Szerencse!
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Flight tests and other aviation performance data: http://www.pbase.com/isegrim

XyZspineZyX
10-03-2003, 11:17 AM
That's for the .Va version and it really does not look too good. Even the Hurri rolls better. Don't you happen to have similar comparison for the later models as well? I mean for the Mk.IX, XIV? Clipped and non-clipped wings?

XyZspineZyX
10-03-2003, 01:10 PM
Why don't you post the graph from NACA Report 868 Issy?

Here are some results:

Spitfire, normal wing:

160mph(IAS) > 87 degrees/sec
210mph > 105 degrees/sec
400mph > 44 degrees/sec

Spitfire, clipped wing:

160mph(IAS) > 128 degrees/sec
210mph > 150 degrees/sec
400mph > 72 degrees/sec

For the Fw190(for comparison)

160mph(IAS) > 114 degrees/sec
210mph > 137 degrees/sec
400mph > 78 degrees/sec


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Message Edited on 10/03/0309:38AM by MiloMorai

XyZspineZyX
10-03-2003, 02:46 PM
I know where this is going. But before all that gets started I just wanted to point out the P-40s curve. Dang! That thing rolls like crazy!

XyZspineZyX
10-03-2003, 03:04 PM
MiloMorai wrote:
- Why don't you post the graph from NACA Report 868
- Issy?
-
- Here are some results:
-
- Spitfire, normal wing:
-
- 160mph(IAS) > 87 degrees/sec
- 210mph > 105 degrees/sec
- 400mph > 44 degrees/sec
-
- Spitfire, clipped wing:
-
- 160mph(IAS) > 128 degrees/sec
- 210mph > 150 degrees/sec
- 400mph > 72 degrees/sec
-
- For the Fw190(for comparison)
-
- 160mph(IAS) > 114 degrees/sec
- 210mph > 137 degrees/sec
- 400mph > 78 degrees/sec


Why don't you post the test in which those roll rates were obtained. Nobody is interested in roll rates for modified planes. NACA modified the planes tested a lot, for research purposes. Post the test Milo, to see the modifications.


The test Isegrim posted is for a combat ready aircraft. Also I posted in the other thread a similar NACA test, giving the same roll rate for Spitfire: max roll rate 60deg/sec at 230mph.


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XyZspineZyX
10-03-2003, 03:11 PM
I know this will probably come as a major shock to you, but I agree with what you have pointed out in your post. The Spitfire was a mediocre roller, particularly the earlier models. Thanks for posting a decorous and well supported argument.



Blutarski

XyZspineZyX
10-03-2003, 03:12 PM
Huckebein_FW wrote:

-
- Post the test
- Milo, to see the modifications.
-
-


Why don't you post the tests done Huckie? That way you could 'put me in my place' without your usual gum flappin./i/smilies/16x16_smiley-happy.gif




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"Only a dead 'chamber pot' is a good 'chamber pot'!"

XyZspineZyX
10-03-2003, 04:46 PM
MiloMorai wrote:
- Why don't you post the graph from NACA Report 868
- Issy?
-
- Here are some results:
-
- Spitfire, normal wing:
-
- 160mph(IAS) > 87 degrees/sec
- 210mph > 105 degrees/sec
- 400mph > 44 degrees/sec
-
- Spitfire, clipped wing:
-
- 160mph(IAS) > 128 degrees/sec
- 210mph > 150 degrees/sec
- 400mph > 72 degrees/sec


Yep, CALCULATED results from the Brits, which is damn obvious from the fact they are giving STRAIGHT roll curves up to 200mph at 50lbs (note that NACA`s engineers were unalbe to deflect the ailrons further than 130 mph, and the cramped canopy enable no more than 40 lbs stickforce). In additition, they didn`t took into account the wing twist - which decreased roll rate by 60% on the Spitifre (only about 35% on the P-47) at speeds, if you read the FULL report... They not even specify exact model... LOL!


On the other hand, we have the testimony`s of REAL Spitfire pilots, like :


This if form Alex Heshaw, the Chief pilot of the Castle Bromwhich Spitfire plant. He basically flew hundreds of Spitfires after they left the factory and were tested for airworthyness.


"I loved the Spit, every Marks of it. But I must admit, that altough later Marks were much faster, they were also progressively inferior to previous Marks in manouveribility. When we checked how a Spit behaves during roll, we counted how many complete rolls we could do under a given time. With the Mark II and V, we did 2 1/2 rolls, but the Mark IX was heavier, and only capable of 1 1/2 rolls. The later, more heavier versions could do even less. Designing an aircraft is about finding balance. It`s hardly possible to improve performance without degrading other properties of the aircraft. "


And this from Jeff Ethell:

"The elevator is very light, while the rudder is stiff and the ailerons even more so. Every Spitfire I have flown take more muscle to roll than most other fighters. As speed increases, both rudder and ailerons get heavier, creating a curious mismatch at high speeds... on has to handle the almost oversensitive elevators with a light fingertip touch while arm-wrestling the stiff ailerons."



And one more word: the NACA report I have shown is for an early MkVA, probably the best rolling of all Spitfires. It`s from the first batch of 78 planes, which still had 8 MGs, but already had the metal ailerons. All later MkVs had Hispano cannons installed in the wings, which decreased roll rate further because of the weight in the wings, and later models, as weight increased (to over 9000 lbs by 1945, 50% more than MkV), roll rate and manouveribilty decreased further.



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'Only a dead Indianer is a good Indianer!'

Vezérünk a Bátorság, K*sérµnk a Szerencse!
(Courage leads, Luck escorts us! - Historical motto of the 101st Puma Fighter Regiment)

Flight tests and other aviation performance data: http://www.pbase.com/isegrim

XyZspineZyX
10-03-2003, 05:03 PM
Isegrim wrote:
All later MkVs had Hispano cannons
- installed in the wings, which decreased roll rate
- further because of the weight in the wings, and
- later models, as weight increased (to over 9000 lbs
- by 1945, 50% more than MkV), roll rate and
- manouveribilty decreased further.

..... a minor point - IIUC, the addition of heavier wing armament would not necessarily reduce the "ultimate" peak roll rate. Added weights out on the wings, relatively far from the roll center would increase inertia, i.e. - reducing initial roll acceleration and deceleration. It would likely only reduce roll rate if the number of revolutions per given unit of time was the criterion of evaluation.


Blutarski




Message Edited on 10/03/03 06:28PM by BLUTARSKI

Message Edited on 10/03/0306:29PM by BLUTARSKI

XyZspineZyX
10-03-2003, 05:22 PM
BLUTARSKI wrote:
- ..... a minor point - IIUC, the addition of heavier
- wing armament would not necessarily reduce the
- "ultimate" peak roll rate. Added weights out on the
- wings, relatively far from the roll center would
- increase inertia, i.e. - reducing initial roll
- acceleration and deceleration. It would likely only
- reduce roll rate if the number of revolution within
- a given unit of time were the criteria of
- measurement.

It would also add to the work that would need to be
done against gravity. Some of this would return as
potential energy as the raised wing with weight
returned again, but friction would mean that the
kinetic-potential-kinetic translation would be lossy.
I have absolutely no idea how much of an issue that
would be. More maths than I am prepared to contemplate
on a Friday!

XyZspineZyX
10-05-2003, 09:38 PM
BLUTARSKI wrote:
- Isegrim wrote:
- All later MkVs had Hispano cannons
-- installed in the wings, which decreased roll rate
-- further because of the weight in the wings, and
-- later models, as weight increased (to over 9000 lbs
-- by 1945, 50% more than MkV), roll rate and
-- manouveribilty decreased further.
-
- ..... a minor point - IIUC, the addition of heavier
- wing armament would not necessarily reduce the
- "ultimate" peak roll rate. Added weights out on the
- wings, relatively far from the roll center would
- increase inertia, i.e. - reducing initial roll
- acceleration and deceleration. It would likely only
- reduce roll rate if the number of revolutions per
- given unit of time was the criterion of evaluation.
-
-
- Blutarski


Well that`s basically a signficant reduction of roll rate, anyway you look at it. Especially as it covers the practical use of roll, where initial roll rate is important.


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'Only a dead Indianer is a good Indianer!'

Vezérünk a Bátorság, K*sérµnk a Szerencse!
(Courage leads, Luck escorts us! - Historical motto of the 101st Puma Fighter Regiment)

Flight tests and other aviation performance data: http://www.pbase.com/isegrim

XyZspineZyX
10-05-2003, 10:40 PM
LFAO hahahaha typical luft Chickens!
Issy & huck are trying to cripple the Spitfire before it even get's in the game. lol Scared your gonna loose your advantage boys?

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XyZspineZyX
10-05-2003, 11:20 PM
ump umph umph...../i/smilies/16x16_smiley-indifferent.gif The plane isnt even HERE yet.............LMAO.....ROFLMAO /i/smilies/16x16_smiley-very-happy.gif /i/smilies/16x16_smiley-very-happy.gif /i/smilies/16x16_smiley-very-happy.gif

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XyZspineZyX
10-06-2003, 12:00 AM
We're only supposed to talk about planes we have?

...





-----------
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XyZspineZyX
10-06-2003, 12:06 AM
Of course, we could always use Issegrim's bible on the 109 rollrate, Paul Coggan.

You know, the quote Isegrim uses to show how the 109 could roll at 80 - 90 deg/sec at 460kp/h with 20lbs stick force.

The exact quote is:

"A full stick roll through 360 degrees at 460kph takes 4 to 4.5 seconds without using rudder, and needs a force of around 20 lbf."

However, the line preceeding it is:

"Roll performance is similar to a Hurricane or elliptical wing tipped Spitfire."

So, using Isegrim's logic, the Spit, with ellipitical wings, rolled at 80 deg/sec at 460 kp/h, with 20lbs stick force.

And of course, the Hurricane rolled the same as well http://ubbxforums.ubi.com/infopop/emoticons/icon_wink.gif

Back in the real world, here's Naca 868, report on lateral control research:

http://naca.larc.nasa.gov/reports/1947/naca-report-868/42.gif


Note that the test Isegrim is using is of a Spit Va, one of the very first Spits to get metal ailerons, (in fact, most Spit Vas had canvas ailerons, so the example Naca tested is almost certainly a prototype), and was done at only 30lbs stick force.

XyZspineZyX
10-06-2003, 12:25 AM
MiloMorai wrote:
-
- Huckebein_FW wrote:
-
--
-- Post the test
-- Milo, to see the modifications.
--
--
-
-
- Why don't you post the tests done Huckie? That way
- you could 'put me in my place' without your usual
- gum flappin.

So will you show it or not? Im really tired of trunkated or twisted tests so come on and show your data completely so we can see if you can be trusted.

Nic

XyZspineZyX
10-06-2003, 12:58 AM
Hop, what you posted there is not a NACA test, it is just data collected by the authors of a post-war summary on lateral control, where the graph you posted is not commented in any way and no sources for the data contained in the chart are given. Link:


http://naca.larc.nasa.gov/reports/1947/naca-report-868/naca-report-868.pdf


On the other hand we the TWO DETAILED NACA TESTS on Spitfire (eliptical wing) roll performance, both comming to same conclusion: 60deg/sec max roll rate reached at 230mph. For this data it can be concluded that Spitfire had a roll performance worse than Emil, and much worse roll performance than 109F and later at high speeds.
This is one of the reports, the other I think it was posted by Isegrim:

http://members.tripod.de/luftwaffe1/aircraft/raf/spit_flying.pdf







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Message Edited on 10/05/0307:00PM by Huckebein_FW

XyZspineZyX
10-06-2003, 01:37 AM
Huck, it's a figure Naca seem to agree with, otherwise they wouldn't have published it.

Also, you have things like the AFDU tests, who compared the Spit XIV to the P-51B:

Rate of Roll
36. The advantage tends to be with the Spitfire XIV.

Now, if the Spit really rolled as shown in those early tests, how badly did the Mustang roll? And why is the Mustang known for it's generally good rollrate?

XyZspineZyX
10-06-2003, 02:03 AM
hop2002 wrote:
- Huck, it's a figure Naca seem to agree with,
- otherwise they wouldn't have published it.

There was no overhead commitee in NACA to aprove or disaprove the data published on this reports. The only persons who seem to agree with it are the authors of the report.

Obviously data was comming from an external source (to NACA), which the authours could not verify. NACA had a hard time to get to test military aeronautic material since it was a civilian agency. This happened during the war but also in postwar years.

This is why no performance testing was done by NACA even though they were better equipped to do it. The only fighter tests at NACA are the handling tests and they are comprehensive. No other allied source did more extensive handling tests, so they are the authority on the matter.

If NACA says that SpitV with metal ailerons had a peak roll of 60deg/sec I have no reason not to believe them.



- Also, you have things like the AFDU tests, who
- compared the Spit XIV to the P-51B:
-
- Rate of Roll
- 36. The advantage tends to be with the Spitfire XIV.
-
-
-
- Now, if the Spit really rolled as shown in those
- early tests, how badly did the Mustang roll? And why
- is the Mustang known for it's generally good
- rollrate?


Such commentaries giving no data have no value whatsoever.
Of course Spit all variants rolled better than Mustang at low speeds and worse at high speeds.


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XyZspineZyX
10-06-2003, 02:32 AM
Huck,

Clearly, wing dimensions were similar between the Spit V and the later Spits. Thus is the basis for you contention that "since the Spit V was a mediocre roller, all subsequent Spits must have been."

But what information do you have to suggest there was never any change to the Spitfire's linkages, improving mechanical advantage, or the installation of tabs or other force softening devices.

Until you can show us definitively that there in ALL apects there were no differences, your assertion at ALL Spits were mediocre rollers is unsupported. You have a report on the V, and it applies only to that aircraft.

Regards,

SkyChimp

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XyZspineZyX
10-06-2003, 02:56 AM
Obsessed with Roll? Let's argue about something else instead I'm bored with roll rates. Who cares. Roll, shmoll, they still shot down plenty of 109s and 190's

How about this.....Oranges are really not orange. I have a test report which concludes that they are a dark yellow....

"If I had all the money I've spent on drink....I'd spend it on drink!"

XyZspineZyX
10-06-2003, 03:13 AM
EPP_Gibbs wrote:
- Obsessed with Roll? Let's argue about something else
- instead I'm bored with roll rates. Who cares. Roll,
- shmoll, they still shot down plenty of 109s and
- 190's


Yeah, let's talk about the exceptional quality of German aircraft builders, like these folks assembling engines for Fw-190s at a BMW factory:

http://www.earthstation1.com/HolocaustFiles/Pics/AllachBMWAircraftPlantUsingConcentrationCampLaborW WII.jpg





Regards,

SkyChimp

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XyZspineZyX
10-06-2003, 04:47 AM
Now something I have never understood is why the clipped wing spit rolled so fast when all that was done was to remove the wing tips?

Did they modify anything else at the same time ?

Did the mod change the airflow over the aileron?

No1RAAF_Pourshot
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No1_RAAF

XyZspineZyX
10-06-2003, 05:33 AM
Great post SkyChimp. Nice to see facts and realities injected into these forums. How refreshing after hearing a buttload of misinformation from all the know-it-all-blowhards in here.....cheers...

mucker

XyZspineZyX
10-06-2003, 05:58 AM
mucker wrote:
- Great post SkyChimp. Nice to see facts and realities
- injected into these forums. How refreshing after
- hearing a buttload of misinformation from all the
- know-it-all-blowhards in here.....cheers...


And those facts were..? Do questions count as facts?


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XyZspineZyX
10-06-2003, 10:55 AM
pourshot wrote:
- Now something I have never understood is why the
- clipped wing spit rolled so fast when all that was
- done was to remove the wing tips?
-
- Did they modify anything else at the same time ?
-
- Did the mod change the airflow over the aileron?
-

I can' give you a detailed explanation, but roll rate is inversely dependant on aspect ratio. Short stubby wings roll better than long slender wings. By removing the wingtips the aspect ratio was reduced so the roll rate had it's dramatic improvement shown on those charts.

It seems to have put the Spit in the same league as the 190 for roll and the 190 was renowned for its ability in this area. I'm guessing, but I reckon the advent of the 190 provided the necessary stimulus for this mod.

The downside of altering the wing shape is the loss of the elliptical planform, which is the most efficient shape as far as induced (lift dependant) drag is concerned. Wing loading must also have increased a little, which will have reduced the turning ability. So you got better roll at the expense of some speed and turn rate (however, you would roll into the turn much quicker).



Kernow
249 IAP

XyZspineZyX
10-06-2003, 02:19 PM
I couldn't prove it easily, but I doubt if the increased roll rate of the clipped-wing Spitfire was due to the reduced mass at the wingtips. The moment of inertia about the roll axis would be decreased, but that would only serve to increase the roll's *acceleration* up to its maximum value. It would not necessarily have any direct effect on the peak roll rate.

The increase in roll rate from the (claimed but dubious) 60 degrees/sec to the 105 deg/sec of the chart in hop2002's post would most likely come from more rigid control linkages and various aerodynamic refinements.

Regards,

RocketDog.

XyZspineZyX
10-06-2003, 02:27 PM
Copperhead310th wrote:
- LFAO hahahaha typical luft Chickens!
- Issy & huck are trying to cripple the Spitfire
- before it even get's in the game. lol Scared your
- gonna loose your advantage boys?
-
-

what advantage?

____________________________________



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____________________________________



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XyZspineZyX
10-06-2003, 02:28 PM
edit double post hmm



Message Edited on 10/06/0303:28PM by Vipez-

XyZspineZyX
10-06-2003, 03:13 PM
Huck, Naca tested a Spit Va with metal ailerons. When this particular plane was delivered to the RAF, it was fitted with fabric ailerons. It was shipped to America in June, just as metal ailerons became available. Was it fitted with metal ailerons in Britain, or American produced ones?

What happened to the plane in the time it was based at Wright Field for evaluation by the USAAF? It later went to Naca at Langley, where it underwent modifications before these roll tests were carried out (Spitfire: the History notes it had a new engine manifold fitted in December, the tests began end of December)

In other words, was it representitive of standard Spitfire Vs with metal ailerons? Did it have any of the modifications that were done to Spitfire ailerons throughout their service life? Which ones?

Holding it up as an example of all metal aileroned Spitfires is silly, because various later marks had different designs of ailerons, of different sizes and shapes, let alone the modifications to linkages etc.

Now, you don't like the comparison to the Mustang rollrate. Even though according to the Naca chart you are presenting, the Spitfire would only outroll the P-51 below 160 mph or so, which could hardly qualify as "advantage tends to be with the Spitfire"

The chart I presented would show that, though, wouldn't it?

However, you don't like the Mustang comparison.

Let's try your's and Isegrim's favourite, the Tempest comparison.

Tempest v 109G2
Rate of Roll
48. At normal speeds there is nothing in it, but at speeds over 350 mph the Tempest could get away from the Me.109G by making a quick change of bank and direction

At normal speeds nothing in it, at 350mph plus the Tempest is better.

Now, same Tempest v Spit XIV:
Rate of Roll
36. The Spitfire XIV rolls faster at speeds below 300 mph, but definitely more slowly at speeds greater than 350.00 mph.

The same conclusion above 350, but at 300 and below the Spitfire "rolls faster" whereas with the 109 "there is nothing in it".

Now, Isegrim is going around quoting the following figures for the Tempest in that test:

- 150 mph : 65
- 200 mph : 84
- 250 mph : 95
- 300 mph : 97
- 350 mph : 94
- 400 mph : 70
- 450 mph : 60

So we can conclude the Spitfire was better than that below 300 mph. (I think Isegrim is wrong, and these Tempest figures are for a later Tempest, with improved ailerons. The comparitive trials were flown with an earlier Tempest. They note that the rate of roll may be improved later on)

XyZspineZyX
10-06-2003, 03:20 PM
Pourshot,

According to Whitford's book, FUNDAMENTALS OF FIGHTER DESIGN, the major factor influencing roll rate is wing span. He states that roll rate varies inversely with the 4th power of the wingspan. Therefore, all other thing being equal, reducing the wingspan of a fighter from 36 feet to 34 feet will theoretically improve roll rate by a factor of about 1.25.

That's basically why bombers are such slow rollers.



Blutarski

XyZspineZyX
10-06-2003, 03:38 PM
Huckebein_FW wrote:
- Hop, what you posted there is not a NACA test, it is
- just data collected by the authors of a post-war
- summary on lateral control, where the graph you
- posted is not commented in any way and no sources
- for the data contained in the chart are given.


The logical extension of your position asks us to accept the notion that NACA/NASA, in their capacity as a clearing house for scientific aeronautical and aerospace research, fails to discriminate in the quality of research which they publish and is happy to disseminate unreliable and unsubstantiated data in this highly technical field. Inasmuch as you have been quite happy to accept NACA data and graphs (including this very same report) when doing your own roll rate calculations, please share with us the secret means by which you can differentiate the suitability of one NACA report from another, or even the "reliable" bits from the "unreliable" parts of a given report.

I think I already know the unhappy answer, but I'm willing to hear your explanation.


Blutarski

XyZspineZyX
10-06-2003, 03:51 PM
BLUTARSKI wrote:
- Huckebein_FW wrote:
-- Hop, what you posted there is not a NACA test, it is
-- just data collected by the authors of a post-war
-- summary on lateral control, where the graph you
-- posted is not commented in any way and no sources
-- for the data contained in the chart are given.
-
-
- The logical extension of your position asks us to
- accept the notion that NACA/NASA, in their capacity
- as a clearing house for scientific aeronautical and
- aerospace research, fails to discriminate in the
- quality of research which they publish and is happy
- to disseminate unreliable and unsubstantiated data
- in this highly technical field. Inasmuch as you have
- been quite happy to accept NACA data and graphs
- (including this very same report) when doing your
- own roll rate calculations, please share with us the
- secret means by which you can differentiate the
- suitability of one NACA report from another, or even
- the "reliable" bits from the "unreliable" parts of a
- given report.
-
- I think I already know the unhappy answer, but I'm
- willing to hear your explanation.
-


I already answered this. The Spitfire roll rate from the chart Hop has posted IS NOT BASED on NACA data. It is just data received by NACA from a postwar source. Spitfire variant is not given, source is not mentioned.

On the other hand we have two extensive and fully reliable tests made by NACA itself which we can read from start to end.

This is why the two NACA tests are much more credible than a chart on unknown model from an unknown source. I hope you can make the distinction.


<center> http://www.stormbirds.com/images/discussion-main.jpg </center>

XyZspineZyX
10-06-2003, 03:57 PM
he he he like your photohttp://ubbxforums.ubi.com/infopop/emoticons/icon_smile.gif

XyZspineZyX
10-06-2003, 04:08 PM
BLUTARSKI wrote:
- Pourshot,
-
- According to Whitford's book, FUNDAMENTALS OF
- FIGHTER DESIGN, the major factor influencing roll
- rate is wing span. He states that roll rate varies
- inversely with the 4th power of the wingspan.
- Therefore, all other thing being equal, reducing the
- wingspan of a fighter from 36 feet to 34 feet will
- theoretically improve roll rate by a factor of about
- 1.25.
-
- That's basically why bombers are such slow rollers.


That's quite a simplistic explanation, Blutarski.

The most important factors in roll rate for an unboosted ailerons (mechanical or hydraulic, not aerodynamic) are:

1) aileron deflection - most of the ww2 fighters settled for a 30 deg total aileron deflection; at high speeds control forces play an important role in setting the limit for aileron deflection;
2) aileron size and type - though chord was aprox the same on most fighters, span differed very much - they were quite long compared with wing semispan at the beginning of the war, but became shorter and shorter as the speeds increased in order to decrease stick forces;
3) distance of the aileron from the center axis of the plane; the bigger the distance the higher the force that can be applied by the pilot; also it is very important the raport between aileron span and wing semispan; the bigger this rapport the better the roll (see point 2));
4) wing aspect ratio and taper; the larger the aspect ratio the smaller the roll rate (though keep in mind that the differences in aspect ratio of ww2 fighters were not big)


Cutting the wing tips on Spitfire affected the roll rate according to points 3) and 4). But it's hard to see how much. In the chart from NACA report it gives a 30 deg better roll rate (seems exagerated though).

It also important to mention that cutting the wing tips does not change the speed at which the peak roll is reached.


<center> http://www.stormbirds.com/images/discussion-main.jpg </center>

Message Edited on 10/06/0310:27AM by Huckebein_FW

XyZspineZyX
10-06-2003, 04:19 PM
nicolas10 wrote:
-
- MiloMorai wrote:
--
-- Huckebein_FW wrote:
--
---
--- Post the test
--- Milo, to see the modifications.
---
---
--
--
-- Why don't you post the tests done Huckie? That way
-- you could 'put me in my place' without your usual
-- gum flappin.
-
- So will you show it or not? Im really tired of
- trunkated or twisted tests so come on and show your
- data completely so we can see if you can be trusted.

So Milo? Any word on this?

Nic

XyZspineZyX
10-06-2003, 04:20 PM
Huckebein_FW wrote:
- That's is quite a simplistic explanation, Blutarski.

..... Yes it is. I was not attmepting to deliver a lecture on the complete spectrum of factors which might influence roll rate performance, only to explain the influence of wingspan. Hence my inclusion of the caveats - "all other things being equal" and "theoretically".


Blutarski

XyZspineZyX
10-06-2003, 04:25 PM
SkyChimp wrote:
- Huck,
-
- Clearly, wing dimensions were similar between the
- Spit V and the later Spits. Thus is the basis for
- you contention that "since the Spit V was a mediocre
- roller, all subsequent Spits must have been."
-
- But what information do you have to suggest there
- was never any change to the Spitfire's linkages,
- improving mechanical advantage, or the installation
- of tabs or other force softening devices.


This is your personal supposition. It is very easy to prove it untrue.

Any improvement to stick forces for a better roll at high speeds, like those you mention, linkages, tabs and so on, would have modified the speeds at which peak roll is reached. Since the speed remained the same, around 230mph, it is clear that modifications were operated to ailerons and wings. Otherways such improvements in roll rate were not possible. We know though that such modifications did not occur during the war after the addition of metal covered ailerons.

Also it is important to note that Spitfire, and generally most ww2 fighters did not suffer from cable stretch problems. Personally I know one single fighter that did, but I won't mention it's name because I don't want to start another flame war. I can say that it is british. That part from NACA report mentioning cable stretch problems pointed to all aircrafts, civilian and military, and most of the data was gathered in interbelic period. Cable stretch problems in ww2 fighters was a rarity.

On the other hand wing twisting at high speeds under aileron load was real. And Spitfire did not receive any improvements in this area during war years. Though it did not suffer more than other fighters from wing twist in roll.




<center> http://www.stormbirds.com/images/discussion-main.jpg </center>

Message Edited on 10/06/0310:27AM by Huckebein_FW

XyZspineZyX
10-06-2003, 06:08 PM
If it can be generally agreed that Figure 47 in NACA Report 868 represents a reasonable degree of validity, examination of the roll rate curves offers some interesting (though NOT totally conclusive) observations -

If one compares peak roll rate to low and high speed roll rates, the following ratios appear -

AIRCRAFT..........160mph.....Max Roll.....400mph

Clipped Spit V ...0.853......1.000........0.480
Spit V normal.....0.829......1.000........0.419
Typhoon...........0.745......1.000........0.527
FW190.............0.698......1.000........0.481

Then consider the American a/c -
P51B..............0.617......1.000........0.883
P47C..............0.690......1.000........0.798
F6F...............0.826......1.000........0.899
P39D..............0.733......1.000........0.640

While the peak roll rates of American a/c are considerably less than their UK and German counterparts, the ratios of high speed roll rate at 400mph versus maximum roll rate in American a/c is very much greater. It seems that American designers appeared to be willing to sacrifice peak roll rate at lower speeds for improved HIGH speed roll rate performance. If the P51B could indeed out-roll a FW190 above 360mph, as the chart suggests, then it would certainly have been able to out-roll a later model Bf109, even at speeds rather under the 360mph figure. If a later model Bf109 displayed roll rate performance, say, 2/3's that of the Fw190 and in the same general conformity versus IAS, then the P47C would also have been able to out-roll the 109 in the high-speed regime.

This certainly cannot be considered a conclusive argument, but is one worthy of some consideration.....


Blutarski

XyZspineZyX
10-06-2003, 06:33 PM
hop2002 wrote:
- Huck, Naca tested a Spit Va with metal ailerons.
- When this particular plane was delivered to the RAF,
- it was fitted with fabric ailerons. It was shipped
- to America in June, just as metal ailerons became
- available. Was it fitted with metal ailerons in
- Britain, or American produced ones?
-
- What happened to the plane in the time it was based
- at Wright Field for evaluation by the USAAF? It
- later went to Naca at Langley, where it underwent
- modifications before these roll tests were carried
- out (Spitfire: the History notes it had a new engine
- manifold fitted in December, the tests began end of
- December)
-
- In other words, was it representitive of standard
- Spitfire Vs with metal ailerons? Did it have any of
- the modifications that were done to Spitfire
- ailerons throughout their service life? Which ones?
-
- Holding it up as an example of all metal aileroned
- Spitfires is silly, because various later marks had
- different designs of ailerons, of different sizes
- and shapes, let alone the modifications to linkages
- etc.


No, silly is your sob story about Spitfire tested. Why would NACA test 6 combat ready fighters, 4 american, 2 british, for 2 months period? just to obtain unrelevant results?? What a ridiculous comment.

Results in the test were perfectly relevant for all the Spits that served during the war. They were actually better than those not fitted with metal covered ailerons or those fitted with wing cannons. Spit IX did not have any modifications to wings and ailerons capable to improve the roll rate (to decrease it, yes) compared to SpitV.

The only serious modification which indeed improved Spit roll performance was the wing clipping. Though it did not modify the speed at which peak roll rate was reached.

Now if Hop has informations about presumptive modifications made to SpitXIV capable to improve the roll rate, I'm ready to listen. But according to Boscombe tests SpitXIV with normal wings had the same roll rate with SpitIX (normal wings).


- Now, you don't like the comparison to the Mustang
- rollrate. Even though according to the Naca chart
- you are presenting, the Spitfire would only outroll
- the P-51 below 160 mph or so, which could hardly
- qualify as "advantage tends to be with the Spitfire"
-
- The chart I presented would show that, though,
- wouldn't it?
-
- However, you don't like the Mustang comparison.

Spit with eliptical wings had a peak roll at slow speeds, so why are you surprised that it has an advantage only up to 200mph?. For clipped wings this advantage goes for another 40mph.



- Let's try your's and Isegrim's favourite, the
- Tempest comparison.
-
- Tempest v 109G2
- Rate of Roll
- 48. At normal speeds there is nothing in it, but at
- speeds over 350 mph the Tempest could get away from
- the Me.109G by making a quick change of bank and
- direction
-
- At normal speeds nothing in it, at 350mph plus the
- Tempest is better.

No, you don't interpret it correctly. When it says "Tempest could get away from the Me.109G by making a quick change of bank and direction." you should read that Tempest has an advantage only if the pilot pulls the max roll. But this advantage is very small because Bf-109G was very much capable of 65-70deg/sec at 400mph.
But I don't blame you, the intention to deceit of the test authors is obvious.



- Now, same Tempest v Spit XIV:
- Rate of Roll
- 36. The Spitfire XIV rolls faster at speeds below
- 300 mph, but definitely more slowly at speeds
- greater than 350.00 mph.
-
- The same conclusion above 350, but at 300 and below
- the Spitfire "rolls faster" whereas with the 109
- "there is nothing in it".
-
- Now, Isegrim is going around quoting the following
- figures for the Tempest in that test:
-
-- 150 mph : 65
-- 200 mph : 84
-- 250 mph : 95
-- 300 mph : 97
-- 350 mph : 94
-- 400 mph : 70
-- 450 mph : 60
-
- So we can conclude the Spitfire was better than that
- below 300 mph. (I think Isegrim is wrong, and these
- Tempest figures are for a later Tempest, with
- improved ailerons. The comparitive trials were flown
- with an earlier Tempest. They note that the rate of
- roll may be improved later on)


That was a BRIEF comparison between SpitXIV and an early TempestV. I won't say again about how many conflicting results those awful british tests have. I just saw a climb test on Bf-109F1/2 in which the brits claim a max climb rate at full throttle at sea level of 2700fpm???!! Compare this with the 3700fpm reached by the real plane! How can somebody come in here and say that british tests are accurate I don't understand. Except for the 5 year campaign of disparaging Bf-109 performance I don't see anything to mention in them.


<center> http://www.stormbirds.com/images/discussion-main.jpg </center>

Message Edited on 10/06/0312:35PM by Huckebein_FW

XyZspineZyX
10-06-2003, 07:00 PM
BLUTARSKI wrote:

- While the peak roll rates of American a/c are
- considerably less than their UK and German
- counterparts, the ratios of high speed roll rate at
- 400mph versus maximum roll rate in American a/c is
- very much greater. It seems that American designers
- appeared to be willing to sacrifice peak roll rate
- at lower speeds for improved HIGH speed roll rate
- performance. If the P51B could indeed out-roll a
- FW190 above 360mph, as the chart suggests, then it
- would certainly have been able to out-roll a later
- model Bf109, even at speeds rather under the 360mph
- figure. If a later model Bf109 displayed roll rate
- performance, say, 2/3's that of the Fw190 and in the
- same general conformity versus IAS, then the P47C
- would also have been able to out-roll the 109 in the
- high-speed regime.


No, your assumption is fundamentally flawed.
190 had a peak roll at low speeds because used long span ailerons like Emils. The difference was that Fw190 used mechanically boosted ailerons, which doubled the force exerted by the pilot and gave Fw190 a peak roll at a slightly higher speed. Without boost it will have the peak roll at the same speeds with Emil and the same roll rate. Because the mechanical boost helped maintain the roll rate competitive at high speeds until the end of war, ailerons were not modified. Bf-109 was modified in 1940, pushing the speed at which the peak roll is reached with 100mph.

With 2/3 aileron deflection at 400mph Bf-109 is capable of 70deg/sec roll rate.




<center> http://www.stormbirds.com/images/discussion-main.jpg </center>

Message Edited on 10/07/0306:53AM by Huckebein_FW

XyZspineZyX
10-06-2003, 08:24 PM
Huckebein_FW wrote:
- With 2/3 aileron deflection at 400mph Bf-109 is
- capable of 70deg/sec roll rate.

Is this the result of one of your famous "calculations" or from an objective test report?

RocketDog.

XyZspineZyX
10-06-2003, 08:45 PM
Ask King George What he thought,,, seen below inspecting the prototype K5054.


Anyone know what bi-plane that was on the right? It seems to have caught someones attention atleast!


Viva good topics without whiners!



http://usuarios.lycos.es/montsia/images/k5054.jpg




Message Edited on 10/06/0309:47PM by Pye

XyZspineZyX
10-06-2003, 08:53 PM
Huckebein_FW wrote:
- No, your assumption is fundamentally flawed.
- 190 had a peak roll at low speeds because used long
- span ailerons like Emils. The difference was that Fw190 (?!) used mechanically boosted ailerons, which gave
- it a peak roll at higher speed. Without boost it
- will have the peak roll at the same speeds with Emil
- and the same roll rate. Because the mechanical boost
- helped maintain the roll rate competitive at high
- speeds until the end of war, ailerons were not
- modified.

Bf-109 was modified in 1940, pushing the
- speed at which the peak roll is reached with 100mph.

..... I take it as an article of faith that the high speed roll performance ofthe 109F/G was considerably improved over that of the Emil. To have re-designed the wing for the F series and not addressed this problem would is simply inconceivable to me. The question remains to what degree did the re-design improve high speed roll rate. I would have no trouble at all believing a figure around 50 degrees per second at 400mph. This would represent a better than four-fold improvement over the Emil, yet would fit with other wartime reports in terms of relative performance versus opposing Allied fighters.


- With 2/3 aileron deflection at 400mph Bf-109 is
- capable of 70deg/sec roll rate.

..... This roll rate value is simply a re-statement of your theoretical calculation, which I decline to accept as conclusive for reasons previously stipulated.

However, for the sake of argument, taking your figure of 70 degree per second on a strictly theoretical basis, a 109F/G would still be out-rolled by any P51B above approx 300mph and by any P51D above 350mph or so. This fits with the anecdotal testimony of wartime American P51 pilots.

Judging from the afore-mentioned NACA graph, a P47 was unable to out-roll a FW190 at any speed. Your calculation for the 109F/G of 70 degrees per second, coupled with a presumably peak roll rate of around 90 degrees per second puts it in a regime where the P47 was also inferior at all speeds in roll performance to the Bf109. If so, then what enemy a/c was the P47 out-rolling to the extent that its pilots were praising the P47's roll abilities? To accept your calculations obligates one to conclude that all the favorable reports of P47 roll performance over Germany are irrational and unfounded. This is just too difficult to believe.


Blutarski

XyZspineZyX
10-07-2003, 11:12 AM
hop2002 wrote:
- Of course, we could always use Issegrim's bible on
- the 109 rollrate, Paul Coggan.
-

We could, because it`s supported by: Marh Hanna, German tests, Finnish roll rate tests. All say 80-90 degree/sec range at 450 kph, two of them indicating explicitly the stick force of 20 lbs, while Hanna leaving little doubt about it.


- You know, the quote Isegrim uses to show how the 109
- could roll at 80 - 90 deg/sec at 460kp/h with 20lbs
- stick force.
-
- The exact quote is:
-
- "A full stick roll through 360 degrees at 460kph
- takes 4 to 4.5 seconds without using rudder, and
- needs a force of around 20 lbf."
-
- However, the line preceeding it is:
-
- "Roll performance is similar to a Hurricane or
- elliptical wing tipped Spitfire."
-
- So, using Isegrim's logic, the Spit, with
- ellipitical wings, rolled at 80 deg/sec at 460 kp/h,
- with 20lbs stick force.
-


Expect that you seem to be unfamiliar with the exact meaning of words in your own language. 'Similar' does not means the 'same', that`s why two words to describe it.

So, "similiar" means that they have roughly the same characteristics, ie. 'similiar' shape of curve but probably not the exact same values. Then Coggan would simply say: it`s the same.

In fact, at 280mph no single test, neither NACA tests or whatever the Brits claim for it, show ~85 deg/sec roll rate (=109F/G/K) for any Spit, and stick forces were considerably heavier than 20 lbs (=109F/G/K), practically double for the Spit. This also points towards that in raw performance the Spit no equal of the 109 udner these circumsances (roll rate, stickforce at given speed). As NACA put it, the primary reason was excessive stick force for ailerons on Spit, not some kind of control surface effiency problem.



- And of course, the Hurricane rolled the same as well
- /i/smilies/16x16_smiley-wink.gif

Indeed, the NACA tells the Spit`s roll rate was practically the same as the Hurris. So you already know what you can expect when Oleg gives the Spitties to us.


-
- Back in the real world, here's Naca 868, report on
- lateral control research:
-
<img
- src="http://naca.larc.nasa.gov/reports/1947/naca-r
- eport-868/42.gif">

Yep, they are quite in disagreement with NACA`s own test.

Not without a reason, the data for Typhoon, 'FW 190A' and 'Spitfire' were supported by the British. In fairness, we all know that RAE is known for getting far lower results for every foreign plane, let it be Axis or Allied, than anybody else, and far higher results for British planes then again in anybody else`s test. British planes do everything better in British tests only - no comment. Just a sidenote.

For example, the FW 190A showed here is the worst roller of the 3 FW190As tested by the British; the two others had considerably (+20-25deg/sec) higher roll rate and lighter ailerons, still, the worst performer was sent for some reason.

The main thing to note that on 868 chart, neither the Spitfire or FW 190 roll rate "curves" show the effect of wing twist; instead, they peak up and suddenly decline, in a harsh manner, unlike in the NACA`s own measured tests, where they show a more curvy line. Note the difference between SpitVA NACA`s curve for P-40 and for NACA868`s P-40 : we know the former does not have the wing twist effects added, the latter probably does. Same goes for NACA868`s 'Spitfire' (what model?), it doesn`t has wing twist effects added. The NACA report itself notes that these effects decrease Spitfire roll rate at speeds by ~65%, compared to ~35% in case of the P-47C, in both cases due to wing twist. I don`t think that even Hop would deny that even his Spitfairy would possess enough wing stiffness against torsional loads.

But I can also think of that the report gives roll data for postwar Spits from the Mk2x series, the first ones that had any major redesign of wings/ailerons ever since introducing metal ailerons. Given the NACA 868 is dated 1947, this is indeed possible.



-
- Note that the test Isegrim is using is of a Spit Va,
- one of the very first Spits to get metal ailerons,
- (in fact, most Spit Vas had canvas ailerons, so the
- example Naca tested is almost certainly a
- prototype), and was done at only 30lbs stick force.
-


Most of this is mere speculation. Fact that the NACA doesn`t mention at all their Spit`s "experimental", or "non-standard nature". As for wheter it was a prototype, it`s easy to tell. You have Spit history book, the Air mininstry number is given, IIRC it`s from the Wxxxx series, a production plane, not from the Xyyyy series, the eXperimental ones. Speaking of experimental Spits : it`s seems that their experimental nature doesn`t offends Mike Williams so much when he presents those as serial plane performance on his site... did you complained about that, too?


As for the stickforce, NACA found 40 lbs to be the maximum force that could be exerted by the pilot, probably due to cramped canopy and the high mounting of the stick. Not that going from 30 to 40 lbs would change things much, IIRC the NACA report mentions that this +10lbs means only that the ailerons could be fully deflected for 130mph maximum instead of 110mph. (IIRC).


http://vo101isegrim.piranho.com/FB-desktopweb.jpg
'Only a dead Indianer is a good Indianer!'

Vezérünk a Bátorság, K*sérµnk a Szerencse!
(Courage leads, Luck escorts us! - Historical motto of the 101st Puma Fighter Regiment)

Flight tests and other aviation performance data: http://www.pbase.com/isegrim

XyZspineZyX
10-07-2003, 11:47 AM
hop2002 wrote:
-
- Holding it up as an example of all metal aileroned
- Spitfires is silly, because various later marks had
- different designs of ailerons, of different sizes
- and shapes, let alone the modifications to linkages
- etc.

Care to expand on that ? The only single change in the design of ailerons on Spifires after adding the metal ones came with the - basically postwar model- Mk 21. All the other seem to have the very same ailerons on all drawings and photos. In fact not even the publicly available AFDU`s handling trials refer even remotely to any kind of improvement in roll rate compared to earlier Mks, in fact it tells about heavier ailerons on MkXIV compared to the MkIX, which agrees well what Heeshaw said on that, even if AFDU`s hypothesis was irregular manufacture standards of Spit components.



-
- Now, you don't like the comparison to the Mustang
- rollrate. Even though according to the Naca chart
- you are presenting, the Spitfire would only outroll
- the P-51 below 160 mph or so, which could hardly
- qualify as "advantage tends to be with the Spitfire"
-
- The chart I presented would show that, though,
- wouldn't it?
-
- However, you don't like the Mustang comparison.


Given that even you admit that no single source shows roll advantage for the Spitfire vs. the P-51 except for very low speeds, one just wonders : how could the Brits come to that rather ridiculus conclusion ?



- Let's try your's and Isegrim's favourite, the
- Tempest comparison.
-
- Tempest v 109G2
- Rate of Roll
- 48. At normal speeds there is nothing in it, but at
- speeds over 350 mph the Tempest could get away from
- the Me.109G by making a quick change of bank and
- direction
-
- At normal speeds nothing in it, at 350mph plus the
- Tempest is better.
-
- Now, same Tempest v Spit XIV:
- Rate of Roll
- 36. The Spitfire XIV rolls faster at speeds below
- 300 mph, but definitely more slowly at speeds
- greater than 350.00 mph.
-
- The same conclusion above 350, but at 300 and below
- the Spitfire "rolls faster" whereas with the 109
- "there is nothing in it".

Which only makes be believe what seems to be evident: tests made by the British are inconsistent with themselves, biased in wording, and unreliable. The Brits say that the Spitfire looses to the Tempest in roll at the very same airspeed as the 109; yet they describe 109 vs. Spit roll rate as if the Spitfire would have advantage at all speeds... funny.Also worthy to notice how much softer words the Brits use regarding their own planes. Whereas in case of foreign planes the phrase is always some kind of "all out superiority " of British aircraft, when comparing domestic a/c vs. domestic a/c, they suddenly go very nice and soft. Then we shouldn`t foret about how in AFDU tests 190s outturn (!!!) 109s, that AFDU seemingly has no idea on even such a simple question what a rated altitude a DB 605A-1 in Bf 109G has (they give totally wrong number of 16.4k ft. - yeah that`s right: for an early Emil, maybe /i/smilies/16x16_smiley-happy.gif ) and so on.

http://vo101isegrim.piranho.com/FB-desktopweb.jpg
'Only a dead Indianer is a good Indianer!'

Vezérünk a Bátorság, K*sérµnk a Szerencse!
(Courage leads, Luck escorts us! - Historical motto of the 101st Puma Fighter Regiment)

Flight tests and other aviation performance data: http://www.pbase.com/isegrim

XyZspineZyX
10-07-2003, 11:55 AM
Historical Tempest roll rates (at 10k ft). Stick force specified.

speed - deg/sec

150 mph : 65
200 mph : 84
250 mph : 95
300 mph : 97
350 mph : 94
400 mph : 70
450 mph : 60

48. At normal speeds there is nothing in it, but at speeds over 350 mph the Tempest could get away from the Me.109G by making a quick change of bank and direction. "

**(Huckbein) No, you don't interpret it correctly. When it says "Tempest could get away from the Me.109G by making a quick change of bank and direction." you should read that (1)Tempest has an advantage only if the pilot pulls the max roll.(1) (2)But this advantage is very small because Bf-109G was very much capable of 65-70deg/sec at 400mph.(2)
But I don't blame you, the intention to deceit of the test authors is obvious.**


(1) and (2) added by Cajun for..... laughter and disbelief, mostly.

(1) Huckbein, exactly where in statement (.48) does it say that? Of course it's max roll, that's why it's max roll rate, being compared to max roll of 109 at those speeds.

(2) Here again is your famous number fudging. Is it just me, or is it creeping down now...... Keep up the damage control, you'll be honest eventually.



Historical Tempest roll rates (at 10k ft). Stick force specified.

speed - deg/sec

150 mph : 65
200 mph : 84
250 mph : 95
300 mph : 97
350 mph : 94
400 mph : 70
450 mph : 60


350 mph = 94 :350mph and below = normal speeds, nothing to it
400 mph = 70 :above 350mph, right? Tempest could get away by quick change, meaning 109 wasn't rolling competitively anymore, so the 109 would be doing LESS THAN 70 degrees per second, and significantly less than 70 to be out rolled enough to be gotten away from.


Good hunting,
Cajun76

"It is the mark of an educated mind to be able to entertain a thought without accepting it."
-Aristotle

XyZspineZyX
10-07-2003, 12:29 PM
If I may, there are no differances in aileron's between clipped and non-clipped wings, so #3 does NOT apply. Also, one critical factor you forgot in your list. MASS!!! Or weight. How much weight the aileron needs to move its critical. In a clipped wing spit, the wings have less weight. Sure it may only be 25/50lb (if even that) but its in the most critical area, the wing tip. 25LB would be nothing if the weight was in the center, but its a big factor with it being on the furthest point from the center, and its even further then the aileron itself.



Huckebein_FW wrote:
-
-
-
- Cutting the wing tips on Spitfire affected the roll
- rate according to points 3) and 4). But it's hard to
- see how much. In the chart from NACA report it gives
- a 30 deg better roll rate (seems exagerated though).
-
- It also important to mention that cutting the wing
- tips does not change the speed at which the peak
- roll is reached.
-
-

No fancy quote or cool photo.... YET

Message Edited on 10/07/0303:35AM by Gibbage1

XyZspineZyX
10-07-2003, 02:32 PM
BLUTARSKI wrote:
- Bf-109 was modified in 1940, pushing the
-- speed at which the peak roll is reached with 100mph.
-
- ..... I take it as an article of faith that the high
- speed roll performance ofthe 109F/G was considerably
- improved over that of the Emil. To have re-designed
- the wing for the F series and not addressed this
- problem would is simply inconceivable to me. The
- question remains to what degree did the re-design
- improve high speed roll rate. I would have no
- trouble at all believing a figure around 50 degrees
- per second at 400mph. This would represent a better
- than four-fold improvement over the Emil, yet would
- fit with other wartime reports in terms of relative
- performance versus opposing Allied fighters.

The roll rate did not increase (not significantly anyway) from Emil to F and later models. Only the speed at which peak roll was reached was different, being 100mph higher. This was done because new tactics emerging required better roll at high speeds. You can read plenty of german aces accounts in which they dive at high speeds on the target (often higher than max speed at that altitude), fire at close range and pull a fast roll to avoid collision. This would have not been possible in an Emil, but it was in F and later models. And stick forces were not excessive, otherways how could thin, poor fed guys like Hartmann achieved such scores employing this technique?



-- With 2/3 aileron deflection at 400mph Bf-109 is
-- capable of 70deg/sec roll rate.
-
- ..... This roll rate value is simply a re-statement
- of your theoretical calculation, which I decline to
- accept as conclusive for reasons previously
- stipulated.
-

It is not a theoretical calculation, NACA gave a direct relationship between helix angle and aileron deflection for speeds below the transonic range. All the effects chronic deniers talk but do not understand do not happen until transonic speeds - ww2 fighters were not made of plastic Blutarski. This is why NACA gives the chart for speeds up to 400mph and some time up to 450mph. Here those effects do not influence significantly the roll. The only reason for roll rate decrease is the limited aileron deflection at high speeds due to heavy stick forces. You can calculate for the planes where is known max aileron deflection at a certain high speed (between 300-450mph) that the ratio Cldelta/Clp is not changing more than 5-10% - this is more than enough accuracy!
We are not interested in calculating roll rates at transonic speeds.



- However, for the sake of argument, taking your
- figure of 70 degree per second on a strictly
- theoretical basis, a 109F/G would still be
- out-rolled by any P51B above approx 300mph and by
- any P51D above 350mph or so. This fits with the
- anecdotal testimony of wartime American P51 pilots.

There is a small difference, true.


- Judging from the afore-mentioned NACA graph, a P47
- was unable to out-roll a FW190 at any speed. Your
- calculation for the 109F/G of 70 degrees per second,
- coupled with a presumably peak roll rate of around
- 90 degrees per second puts it in a regime where the
- P47 was also inferior at all speeds in roll
- performance to the Bf109. If so, then what enemy a/c
- was the P47 out-rolling to the extent that its
- pilots were praising the P47's roll abilities? To
- accept your calculations obligates one to conclude
- that all the favorable reports of P47 roll
- performance over Germany are irrational and
- unfounded. This is just too difficult to believe.


P47 pilot also claimed that they could outturn everything.
It's not here the place to disccus the accuracy of pilot reports.


<center> http://www.stormbirds.com/images/discussion-main.jpg </center>

XyZspineZyX
10-07-2003, 02:49 PM
Huckebein_FW wrote:
- The roll rate did not increase (not significantly
- anyway) from Emil to F and later models. Only the
- speed at which peak roll was reached was different,
- being 100mph higher. This was done because new
- tactics emerging required better roll at high
- speeds. You can read plenty of german aces accounts
- in which they dive at high speeds on the target
- (often higher than max speed at that altitude), fire
- at close range and pull a fast roll to avoid
- collision. This would have not been possible in an
- Emil, but it was in F and later models. And stick
- forces were not excessive, otherways how could thin,
- poor fed guys like Hartmann achieved such scores
- employing this technique?


..... We agree on the above statement.
-
-
-
--- With 2/3 aileron deflection at 400mph Bf-109 is
--- capable of 70deg/sec roll rate.
--
-- ..... This roll rate value is simply a re-statement
-- of your theoretical calculation, which I decline to
-- accept as conclusive for reasons previously
-- stipulated.
--
-
- It is not a theoretical calculation,


...... Blottog, who is professionally trained in this field disagrees with your interpretation. You and I will have to agree to disagree on this point.
-
-
-
-- However, for the sake of argument, taking your
-- figure of 70 degree per second on a strictly
-- theoretical basis, a 109F/G would still be
-- out-rolled by any P51B above approx 300mph and by
-- any P51D above 350mph or so. This fits with the
-- anecdotal testimony of wartime American P51 pilots.
-
- There is a small difference, true.
-
-
-- Judging from the afore-mentioned NACA graph, a P47
-- was unable to out-roll a FW190 at any speed. Your
-- calculation for the 109F/G of 70 degrees per second,
-- coupled with a presumably peak roll rate of around
-- 90 degrees per second puts it in a regime where the
-- P47 was also inferior at all speeds in roll
-- performance to the Bf109. If so, then what enemy a/c
-- was the P47 out-rolling to the extent that its
-- pilots were praising the P47's roll abilities? To
-- accept your calculations obligates one to conclude
-- that all the favorable reports of P47 roll
-- performance over Germany are irrational and
-- unfounded. This is just too difficult to believe.
-
-
- P47 pilot also claimed that they could outturn
- everything.


..... Not so, and never the basis for P47 tactics. Yet, it is claimed that the P47 apparently had superior sustained turn performance at very high altitude due to its high degree of retained power.


- It's not here the place to disccus the accuracy of
- pilot reports.


..... Agreed.



Blutarski

XyZspineZyX
10-07-2003, 02:56 PM
Cajun76 wrote:
-
- 48. At normal speeds there is nothing in it, but at
- speeds over 350 mph the Tempest could get away from
- the Me.109G by making a quick change of bank and
- direction. "
-
- **(Huckbein) No, you don't interpret it correctly.
- When it says "Tempest could get away from the
- Me.109G by making a quick change of bank and
- direction." you should read that (1)Tempest has an
- advantage only if the pilot pulls the max roll.(1)
- (2)But this advantage is very small because Bf-109G
- was very much capable of 65-70deg/sec at 400mph.(2)
- But I don't blame you, the intention to deceit of
- the test authors is obvious.**
-
-
- (1) and (2) added by Cajun for..... laughter and
- disbelief, mostly.
-
- (1) Huckbein, exactly where in statement (.48) does
- it say that? Of course it's max roll, that's why
- it's max roll rate, being compared to max roll of
- 109 at those speeds.

An Fw-190 could easily outturn a Tempest at 300mph without pulling max roll rate. This would like the authors of the test to make the readers believe. But they can't despite the poisonous bias they poured in report. They say: "At normal speeds there is nothing in it," meaning that Bf-109 reaches the peak roll at slightly slower speed, and roll better than Tempest, but of course that does not matter!!?? Isn't that laughable? What matters for the testers is that they found a small, indiscernable advantage at speeds over 350mph. IF there really was such advantage, considering the long history of distorted results in british testing of Bf109.


- (2) Here again is your famous number fudging. Is it
- just me, or is it creeping down now...... Keep up
- the damage control, you'll be honest eventually.
-
-
-
- Historical Tempest roll rates (at 10k ft). Stick
- force specified.
-
- speed - deg/sec
-
- 150 mph : 65
- 200 mph : 84
- 250 mph : 95
- 300 mph : 97
- 350 mph : 94
- 400 mph : 70
- 450 mph : 60
-
-
- 350 mph = 94 :350mph and below = normal speeds,
- nothing to it
- 400 mph = 70 :above 350mph, right? Tempest could
- get away by quick change, meaning 109 wasn't rolling
- competitively anymore, so the 109 would be doing
- LESS THAN 70 degrees per second, and significantly
- less than 70 to be out rolled enough to be gotten
- away from.


That never happened Cajun, they also say that 109F2 climbed initialy at 2700fpm instead of 3700fpm, in comparison with SpitV, which amazingly reached 4200fpm instead of 3200fpm??!!, the real climb performance for the SpitV in service at that time. Such disturbing errors, lies or simply pure propaganda cannot be confounded with serious testing.


<center> http://www.stormbirds.com/images/discussion-main.jpg </center>

Message Edited on 10/07/0309:10AM by Huckebein_FW

XyZspineZyX
10-07-2003, 04:29 PM
Is this the usual 'German planes were fantastic and the Russian/American/British planes were crap' thread?

Isegrim and Huckebein are both hear so it must be.

XyZspineZyX
10-07-2003, 04:34 PM
Not 'fantastic' but "uber"./i/smilies/16x16_smiley-wink.gif The LW a/c were perfection personified, not one fault they had./i/smilies/16x16_smiley-very-happy.gif


http://www.stenbergaa.com/stenberg/west-battleline.jpg



"Only a dead 'chamber pot' is a good 'chamber pot'!"

XyZspineZyX
10-07-2003, 04:46 PM
Huckebein_FW wrote:

- That never happened Cajun,

Are you claiming that the Allied tests never actually took place and were fabricated?

Regards,

RocketDog.

XyZspineZyX
10-07-2003, 04:51 PM
BLUTARSKI wrote:
- Huckebein_FW wrote:
-- It is not a theoretical calculation, NACA gave a
-- direct relationship between helix angle and aileron
-- deflection for speeds below the transonic range. All
-- the effects chronic deniers talk but do not
-- understand do not happen until transonic speeds -
-- ww2 fighters were not made of plastic Blutarski.
-- This is why NACA gives the chart for speeds up to
-- 400mph and some time up to 450mph. Here those
-- effects do not influence significantly the roll. The
-- only reason for roll rate decrease is the limited
-- aileron deflection at high speeds due to heavy stick
-- forces. You can calculate for the planes where is
-- known max aileron deflection at a certain high speed
-- (between 300-450mph) that the ratio Cldelta/Clp is
-- not changing more than 5-10% - this is more than
-- enough accuracy!
-- We are not interested in calculating roll rates at
-- transonic speeds.

-
-
- ...... Blottog, who is professionally trained in
- this field disagrees with your interpretation. You
- and I will have to agree to disagree on this point.
--


Read again what Blotto really says:



- Blottogg wrote:
-- Sorry to bring this up again, but I've got a couple
-- of points to mention about it. Even though it's for
-- a Spitfire, the aircraft are contemporaries, and
-- hopefully somewhat similar. The slope of pb/2V is
-- roughly linear, but they only have data for speeds
-- up to 295 mph. I wish they'd included a higher
-- speed run. For the 295 mph plot, there is a slight
-- flattening of the slope, or the value of V
-- (velocity) is increasing a little faster than p
-- (roll in radians/sec). Also important to note is
-- that at 295 mph, the Spitfire pilot can't get more
-- than about 20 deg. of aileron deflection. This is
-- why I'm saying that the article here:
--
-- <a
-- href="http://naca.larc.nasa.gov/reports/1941/naca-
-- report-715/naca-report-715.pdf"
-- target=_blank>http://naca.larc.nasa.gov/reports/19
-- 41/naca-report-715/naca-report-715.pdf</a>
--
--
-- can't be extrapolated to high speeds. I re-read the
-- article but couldn't find any reference to the
-- relationship holding true through the transonic
-- range.


He says that the relationship cannot be extrapolated to TRANSONIC SPEEDS. This is also why NACA made it's roll rate charts up to 400mph, at transonic speeds the roll rate is affected significantly (reasons mentioned).

But at 400mph we are firmly below transonic speeds, and those effects have a minor effect: only 10-15% difference in Cldelta/Clp at 400mph for most planes.

If we consider a max roll for Bf-109 of 85deg/sec at 450km/h with full aileron deflection, then at 650km/h the roll rate will be:

p2 ~ p1 * (v2/v1) * (delta_a2/delta_a1) ~ 85 * (650/450) * (2/3) ~ 81 deg/sec

Now let's see how much will affect this result the 15% difference in Cldelta/Clp ratio at 400mph:

p2 = 81 * 0.85 = 69 deg/sec

In other words 70 deg/sec is perfectly realistic. Take a look at that NACA chart with roll rates, put a max roll at say 290mph then decrease the roll with a translated line from P-51B graph above it (Bf-109 does not suffer from wing twist more than P-51, at least in 300-400mph speed range). You'll get basically the same results, around 70 deg/sec.



<center> http://www.stormbirds.com/images/discussion-main.jpg </center>

Message Edited on 10/07/0302:12PM by Huckebein_FW

XyZspineZyX
10-07-2003, 05:02 PM
RocketDog wrote:
-
- Huckebein_FW wrote:
-
-- That never happened Cajun,
-
- Are you claiming that the Allied tests never
- actually took place and were fabricated?


Are you claiming that 2700fpm climb at sea level (full throttle) for F2 is correct????

They obtained this result in a ridiculous comparison made in '42 between what they called an operational SpitV and 109F2. The results are stunning: SpitV had an initial climb of 3700fpm instead of 3200fpm correct for an SpitV (9lb boost) operational in '42, and F2 only 2700fpm instead of 3700fpm (1.3 ata).

How do you call this RocketDog?
"Fabrication" seems a kind word to me.


<center> http://www.stormbirds.com/images/discussion-main.jpg </center>

Message Edited on 10/07/0311:13AM by Huckebein_FW

XyZspineZyX
10-07-2003, 06:52 PM
Sorry to be getting to the party late yet again. I'll let the 109 roll thread die a natural death and comment here.

Huck, thanks for reposting the part of my post I wanted to expand on. I'm going to have to disagree on you as to how far the roll equation from the NACA report can be extrapolated. Where roll response becomes non-linear will vary from aircraft to aircraft, but the data you showed from the Spitfire shows its roll going non-linear at about 300 mph. Given the Spitfire's similarities (cockpit, wing construction) to the 109, I'm going to assume the 109 went non-linear at about 300 mph too. The Spitfire plot also shows a deflection limitation similar to the 109's as speed built up.

Kernow, excellent explanation of the effects of clipped wings (BTW, you'll lose a little ceiling and range without the tips too, though speed was actually a little higher without the tips IIRC.) Gibb, you're right about the clipped tips reducing mass just where you'd want to in order to increase initial roll rate. The mass was fairly small though, and wasn't the dominant factor, even given the strategic location.

Blutarski, good comments and use of Whitford (I really like his books.) I'll add one observation to his comment on span reducing roll rate (I'd gotten the relationship wrong in a P-38 post... my bad.) Another problem with the unclipped wings is that the ailerons are inboard of the tips (it's structurally hard to get ailerons extended to the tips of an elliptical wing.) Any wing surface outboard of the ailerons has to be dragged around in roll by the ailerons at a mechanical disadvantage. This might have helped avoid wing twist at high speeds for the same leverage reasons though. I'm not surprised the roll improved after the tips were removed, though I am surprised at how large the improvement was. Another example of why these things get flight-tested instead of relying only on engineers and their equations. AaronGT, you're right, too. But like you, just the thought of the math makes my head hurt, and the losses due to larger P.E. and K.E. values changing hands would be very small order for such a small amount of mass.

Issy, the only thing that surprised me from your initial post was that NACA didn't find any aeroelastic (wing bending) effects on the Spitfire. Did the report note what speeds the roll tests were done at? The ailerons could have gotten heavy before any wing twist effects became evident. The table Huck posted tells me the wing started twisting at about 300 mph.

It also took me a second to figure out why the P-36 and P-40 curves were so cusped. My best guess is that the Curtiss aircraft had much nastier adverse yaw characteristics than the British fighters. If that were the case, their curves would flatten out if the Curtiss pilots had been allowed to use pro rudder. Good call by Issy on inertia's relevance to combat as well. While Blutarski and myself (previously on this same point) are correct that lateral mass affects initial roll rate, not ultimate, in combat this effect is more pronounced. Combat usually involves rolls of 90-180 degrees, not multiples of 360 sometimes done in testing (or when pilots are bored... my record is 13 360's in a row.)

Milo, the numbers you posted look a little high to me. Where did you get them from, and were they flight data, or theoretical calculations as Issy indelicately suggested?

Anybody know what changes were made to the Spit's wings besides the clipped tips? Specifically structural, control surface, linkage or airfoil changes? I haven't found anything yet, but I'll keep looking.

A (mostly) civil discussion of aircraft performance. Who'd 'a thunk it?

Blotto

"Only the spirit of attack, born in a brave heart, will bring success to any fighter craft, no matter how technically advanced." - A. Galland

"Look, do you want the jets, or would you rather I slap the props back on?" - W. Messerschmitt

http://home.mindspring.com/~blottogg/sitebuildercontent/sitebuilderpictures/14fsPatch.gif

XyZspineZyX
10-07-2003, 07:49 PM
Blottogg wrote:
- Sorry to be getting to the party late yet again.
- I'll let the 109 roll thread die a natural death and
- comment here.
-
- Huck, thanks for reposting the part of my post I
- wanted to expand on. I'm going to have to disagree
- on you as to how far the roll equation from the NACA
- report can be extrapolated. Where roll response
- becomes non-linear will vary from aircraft to
- aircraft, but the data you showed from the Spitfire
- shows its roll going non-linear at about 300 mph.
- Given the Spitfire's similarities (cockpit, wing
- construction) to the 109, I'm going to assume the
- 109 went non-linear at about 300 mph too. The
- Spitfire plot also shows a deflection limitation
- similar to the 109's as speed built up.


Blotto I'm afraid that the civil conversation will end right here.
NACA relationship is verified up to 400mph, with the precautions taken - lowering the roll rate obtained with 10% from the result calculated gives a extremely prudent estimation.

Your comparison with Spitfire has no basis.
Cockpit similarities does not affect in any way the roll rate at high speeds, the stick could not be fully deflected at that speed, so there's no real obstacle because of cockpit there. As a side note it is worth mentionioning that the real obstacle in side stick deflection are not the side panels of the cockpit, but pilot legs, and this is true for all cockpits.
To see similarities between Spitfire and Bf-109(F&later) wing construction is just ridiculous. Where are those similarities Blotto, can you point them out? You see similarities but at the same time you ask Hop about Spitfire wing??
Have you already forgot that at the time of the test Bf-109 wing had only one year whereas the Spitfire wing was designed 6 years before (with exception of metal covered ailerons, the wing was basically the same)? Have you heard that Bf-109 had VERY GOOD torsional rigidity, as revealed in allied tests? How can you compare Spitfire roll rate with Bf-109(F&later)? Spitfire ailerons could not be deflected fully at speeds over 210Km/h!!! whereas Bf-109 could at least up to 450km/h. Have you considered that Spitfire had the thinnest airfoil of it's time, and was notorious for wing failures? How can someone expect that Spitfire and Bf-109 to twist the same way?

What I see here is just your unwillingness to accept an obvious result, giving absolutely ZERO arguments.


<center> http://www.stormbirds.com/images/discussion-main.jpg </center>

Message Edited on 10/07/0301:52PM by Huckebein_FW

XyZspineZyX
10-07-2003, 07:56 PM
Huckebein_FW wrote:


- Read again what Blotto really says:

..... No need to. I'm good at reading comprehension. Your own quotation of Blottog's comments makes my point -

QUOTE -

--- The slope of pb/2V is
--- roughly linear, but they only have data for speeds
--- up to 295 mph. I wish they'd included a higher
--- speed run. For the 295 mph plot, there is a slight
--- flattening of the slope, or the value of V
--- (velocity) is increasing a little faster than p
--- (roll in radians/sec).

and

--- can't be extrapolated to high speeds. I re-read the
--- article but couldn't find any reference to the
--- relationship holding true through the transonic
--- range.

- UNQUOTE

Blottog states that the NACA values to which you refer are only plotted up to 295mph. He goes one to state that, even at 295mph, the speed and roll rate plots begin to diverge.

The only mention of trans-sonic speeds is his statement to the effect that he could find no mention in the NACA document that the parallel relationship between speed and roll rate, which appears at lower air speeds, remained true at trans-sonic speeds. I believe that this was in reply to a claim in the direction made by your goodself

It seems to be Blottog's position that, with respect to the graph under discussion. divergence had already started at the 295mph. There is at least another 150mph to go before we even start talking about trans-sonic speeds. Hence my skeptical position on this point.

I'd really like to see some some confirmed historical numbers on this point. derived from actul a/c test. Isegrim has produced a document claiming a 109G/K roll rate of 90 odd degrees @ high speed (don't recall exact numbers). I've asked him to confirm details of the exact pedigree of this data, but have yet to see a response from him.



Blutarski

XyZspineZyX
10-07-2003, 08:11 PM
Blottogg wrote:
- A (mostly) civil discussion of aircraft performance.
- Who'd 'a thunk it?


We did not want to wake the children again .....;-}



Blutarski

XyZspineZyX
10-07-2003, 08:19 PM
BLUTARSKI wrote:
-
- Blottog states that the NACA values to which you
- refer are only plotted up to 295mph. He goes one to
- state that, even at 295mph, the speed and roll rate
- plots begin to diverge.

It started to diverge at 300mph because Spitfire suffered from wing twist problems.

When I did the calculation I took into account this divergence, as found in P-47 chart (with dependence between helix angle and aileron deflection): 15 procent at 400mph.

Keep in mind that P-47 also suffered quite severely from wing twist at high speeds, as reported by NACA. Therefore using 15% deviation at 400mph for Bf-109 which did not have this problems (until transonic range) most probably will give results below the real value of roll rate at that speed.

A 70deg/sec roll rate at 400mph is a very prudent value.


<center> http://www.stormbirds.com/images/discussion-main.jpg </center>

XyZspineZyX
10-07-2003, 08:42 PM
Huckebein,

As I said, we'll have to agree to disagree on the accuracy of your calculations. Your numbers may perhaps be exactly correct. But until some definitive historical data can be found to confirm or deny them, they still remain strictly in the theoretical realm.



Blutarski

XyZspineZyX
10-07-2003, 08:56 PM
Huck, we were doing so well there for a minute. The roll performance for the 109 you and Issy keep quoting is for a tab-equipped aircraft. Most of us seem agreed that this was the exception for the 109. Only Issy, and perhaps you, seem to think this was the rule. I have never doubted a 109K (tab equipped) pilot's ability to deflect the ailerons 2/3 at 770 kph. I do doubt this was indicative of the non-tab equipped majority of 109's.

I'm missing NACA's verification of its calculated roll performance to 400 mph. Was this in Report 715, or another report?

You're right; I don't know particular structural variations that correspond to particular Spitfire models. I do know that they both had a single spar wing structure. BTW, in the 109 thread SkyChimp posted a cutaway drawing that showed an I-beam spar for the 109, not a torsion box. It's just a drawing, but I'm wondering why you never commented on this. I don't have any torsional resistance figures for the 109 or the Spitfire (nor do you), but based on what I do know of their structures, I don't think that either qualified as paragons of wing stiffness.

As to the cockpit similarities, both were narrow, restricting lateral arm movement. The limiting factor wasn't the stick hitting the cockpit wall, but the pilot's inability to stick an elbow out for better leverage. AFAIK, lateral foot displacement was similar for both giving a similar base to anchor the pilot's torso, though the 109 pilot was more reclined. The narrow cockpits seem to have limited the amount of lateral force both pilots could exert in either aircraft, according to previously posted reports. Do you have anything to counter this?

As far as comparing roll rates, I didn't specify types when comparing the 109 to the Spitfire. But using Issy's graph:

http://www.x-plane.org/users/isegrim/spitI_109E_ailerons.jpg


It looks like the Spitfire Mk I was slower at low speeds (I'm guessing due to the larger, elliptical wing) and marginally faster at high speeds (though "less slow" would probably be more accurate.) This was probably due to the relatively inboard position of the Spitfire's aileron, as I mentioned previously. That the Spitfire pilot could exert more force seems counter to the confined space argument, but does nullify your belief that foot displacement was key (if you were referring to lateral foot displacement.) More likely the upright position of the Spitfire pilot allowed for a little better leverage. Neither pilot could throw a shoulder into it with his elbow out, though. The Spitfire's spade stick had its pivot for roll control higher than its pitch pivot (which was on the floor), so both pilots were short-changed roll leverage in the interest of getting the stick to clear their knees. Finally, Issy's graph also shows time to roll to only 45 deg. The Spitfire's wing armament wasn't it helping here, nor were the 109E's MGFF's (as previously discussed concerning initial roll rates.)

I know the Spitfire had wing failures in its career, and that it had a thin airfoil. With its greater chord though, its spar depth should have been similar to the 109. Got any dimensions to shine some light on this?

Try not to let personal bias enter this. I don't have an axe to grind regarding either the 109 or the Spit. I'm assuming Issy does regarding the Spit. I don't think he started this thread on a quest for knowledge. You seem to be a lot more inclined to challenge data showing the 109 in a poor light (or its competition in a favorable light), while you and Issy are much more credulous (accepting, willing to believe) regarding favorable 109 data. Do you guys want to figure out how they flew, or would you rather try and selectively backfill preconceived notions? If it's the latter, let me know now and I'll go plug in a DVD before they're overdue at Blockbuster.

Blotto

"Only the spirit of attack, born in a brave heart, will bring success to any fighter craft, no matter how technically advanced." - A. Galland

"Look, do you want the jets, or would you rather I slap the props back on?" - W. Messerschmitt

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XyZspineZyX
10-07-2003, 09:40 PM
Huckebein_FW wrote:
- RocketDog wrote:
--
-- Huckebein_FW wrote:
--
--- That never happened Cajun,
--
-- Are you claiming that the Allied tests never
-- actually took place and were fabricated?
-
-
- Are you claiming that 2700fpm climb at sea level
- (full throttle) for F2 is correct????
-

Actually, I'm not claiming anything, I'm just trying to determine the truth. Although I have to say I find it unlikely in the extreme that Allied airforces systematically falsified test reports of German aircraft.

Overall, the problem I have with your analyses is that you seem to dismiss in advance evidence which contradicts what you "know" to be the truth and go on to build elaborate hypotheses on slender evidence. In other words, it looks very much like you've already made up your mind and are going shopping for evidence to support your preconceived conclusions. This isn't the way that an engineering or scientific analysis can proceed.

So we see you dismiss Allied tests of aircraft because they are "biased propoganda", but you convince yourself that the 109 had a satisfactory roll rate at high speed, or whatever, by claiming against the evidence that it had Fletner tabs, or by uncritically accepting (in this case at face value) a report about aileron deflection, or by accepting that one can apply a rather simplified equation from an NACA report without qualification.

This lack of skepticism and contextual subtlety probably reflects the fact that, as you've admitted, you don't have an engineering or physics background. In fact, it's notable that those with such backgrounds are far more cautious in drawing conclusions about aircraft performance from slender evidence (e.g., Blottog and Blutarski). For myself, I am not an aeronautical engineer by training, but I do have a PhD in physics and work as a Senior Lecturer in an engineering department at a well-regarded UK university. With my background I find your claims about the performance of the Bf 109 unconvincing because they appear ill founded.

As for why you should be so determined to force the evidence to fit one particular set of pre-decided conclusions, I can only guess.

All of this is a great shame, because you appear genuinely interested in aircraft. But until you can start to engage in some sort of rational discussion based on a mature engineering or scientific approach I suspect that more and more people will just stop reading what you have written.

Regards,

RocketDog.

XyZspineZyX
10-07-2003, 10:08 PM
RocketDog wrote:
- This lack of skepticism and contextual subtlety
- probably reflects the fact that, as you've admitted,
- you don't have an engineering or physics background.
- In fact, it's notable that those with such
- backgrounds are far more cautious in drawing
- conclusions about aircraft performance from slender
- evidence (e.g., Blottog and Blutarski).


I possess no formal engineering or physics background, beyond having flunked out of Rensselaer Polytechnic Institute a long time ago (excessive partying; insufficient maturity). Outside of an enthusiastic amateur interest in evaluating military aviation, my only real qualification is possession of a reasonably logical and careful mind.



Blutarski

XyZspineZyX
10-07-2003, 10:32 PM
- So, "similiar" means that they have roughly the same
- characteristics,

Yes.

- In fact, at 280mph no single test, neither NACA
- tests or whatever the Brits claim for it, show ~85
- deg/sec roll rate (=109F/G/K) for any Spit, and
- stick forces were considerably heavier than 20 lbs
- (=109F/G/K), practically double for the Spit.

So you dontend "similar" means "double"?

Odd version of English they're teaching in Hungary.

-- Back in the real world, here's Naca 868, report on
-- lateral control research:

- Yep, they are quite in disagreement with NACA`s own
- test.

You'll also note Naca's later report gives different values to the P-40 to their earlier report. Higher at low speeds, lower at high speeds. Perhaps they revised their methods during the war?

- Not without a reason, the data for Typhoon, 'FW
- 190A' and 'Spitfire' were supported by the British.

Interesting you mention the 190 data is supplied by the British.

- In fairness, we all know that RAE is known for
- getting far lower results for every foreign plane,
- let it be Axis or Allied, than anybody else,

Really? When the US Navy tested the 190 and Corsair, they found they had similar rollrates. The British Air Commission forwarded the data from British tests, that gave the 190 a rollrate twice as good.

http://www.hitechcreations.com/forums/showthread.php?s=&threadid=87239

It's about half way down, a scan of a page from F4UDOA. Notice that these British figures are the ones accepted by Naca for the 190.

- For example, the FW 190A showed here is the worst
- roller of the 3 FW190As tested by the British; the
- two others had considerably (+20-25deg/sec) higher
- roll rate and lighter ailerons, still, the worst
- performer was sent for some reason.

Where have you seen that, Isegrim? Got a source, perhaps?

The report notes that "our pilots" have NOW flown 3 190s, and the test machine had heavier ailerons than the others. No mention of a difference in roll rates, or explanation of why this plane was chosen. It could be the others were damaged, not available for testing, or had not even been captured when the tests were carried out.

Regardless, if the report was an attempt to falsify the results, why mention it at all, and why did the 190 come out with the best rollrate?

- The main thing to note that on 868 chart, neither
- the Spitfire or FW 190 roll rate "curves" show the
- effect of wing twist; instead, they peak up and
- suddenly decline, in a harsh manner, unlike in the
- NACA`s own measured tests, where they show a more
- curvy line.

On the contrary, they do.

Wing twist is minor compared to stick force limits, for example the report notes the rolrate for the 190 would be 15 deg/sec per degree of deflection at 350 IAS.

That would be 255 deg/sec at 350, with rigid wings and unlimited stick force (assuming it could take the structural load)

The actual figure, with wing twist, was about 11 deg/sec per degree of deflection,for a theoretical roll rate of 187 deg/sec at 350 IAS.

As you can see, the real rate they achieved with 50lbs stick force was 95 deg/sec. The effect of wing twist is masked by the drop off due to stickforce limits being exceeded.

The diagram has already been posted here, you could have worked it out for yourself before coming up with such a silly suggestion.

Which brings us to the Naca tests. Whilst searching for the doc from F4UDOA on the AH board, I found an interesting post from Gripen, who has done a lot of research. Like Butch, I've never seen Gripen really wrong on an issue.

According to Gripen:

"It appears that there is a problem with older NACA roll rate charts. It seems that they measured peak roll rate at one speed and then calculated chart using this rate and controll force limits. That P-40 roll rate graph in the AHT is a good example; wing twist and spongines of the controll system does not show up in the chart. Reports showing this can be found from here (P-36, P-40, Spit and Hurri report vs P-40F report, also P-63 report shows this)."


Now, let's compare the P-40 in that early Naca report with the one in the post war Naca report.

According to the early report, the P-40 did 110 deg/sec with only 30 lbs stick force, at 260 IAS.

And yet the post war report gives it only 95 deg/sec, with 50lbs stick force.

- Note the difference between SpitVA
- NACA`s curve for P-40 and for NACA868`s P-40 : we
- know the former does not have the wing twist effects
- added, the latter probably does.

So you admit the early Naca tests don't have wing twist "added", which means they cannot be measured results, but calculated?

- Same goes for
- NACA868`s 'Spitfire' (what model?), it doesn`t has
- wing twist effects added.

Of course it has wing twist. The wing twist is masked by the drop due to limited stick force.

- As for wheter it was a
- prototype, it`s easy to tell. You have Spit history
- book, the Air mininstry number is given, IIRC it`s
- from the Wxxxx series, a production plane, not from
- the Xyyyy series, the eXperimental ones.

It's experimental in that it was used for experimental evaluations by the USAAF. For instance, I pointed out that the ailerons are certainly not factory fitted, and may be locally made, the engine had certainly undergone work, etc. There isn't much in the Naca report on the condition, is there?

Still, it hardly matters since you've admitted these are calculated, not experimentaly derived figures.
And even Naca chose not to use those figures in their post war report, not for the Spit OR the P-40.

- As for the stickforce, NACA found 40 lbs to be the
- maximum force that could be exerted by the pilot,
- probably due to cramped canopy and the high mounting
- of the stick.


It says the pilot could only exert "about" 40lbs, which implies they were not even measuring accurately. It doesn't say why. In British tests, they had no problem exerting 50lbs force.


-- Holding it up as an example of all metal aileroned
-- Spitfires is silly, because various later marks had
-- different designs of ailerons, of different sizes
-- and shapes, let alone the modifications to linkages
-- etc.
-
- Care to expand on that ? The only single change in
- the design of ailerons on Spifires after adding the
- metal ones came with the - basically postwar model-
- Mk 21. All the other seem to have the very same
- ailerons on all drawings and photos.

No, they increased the thickness (and rigidity) of the cables in the aileron circuit, changed the angle of droop, raised the leading edge of the wing (not strictly an aileron issue) and changed the area and span of the ailerons.

- In fact not
- even the publicly available AFDU`s handling trials
- refer even remotely to any kind of improvement in
- roll rate compared to earlier Mks, in fact it tells
- about heavier ailerons on MkXIV compared to the
- MkIX,

Does it?

Rate of Roll
19. Rate of roll is very much the same.


- Given that even you admit that no single source
- shows roll advantage for the Spitfire vs. the P-51
- except for very low speeds, one just wonders : how
- could the Brits come to that rather ridiculus
- conclusion ?

Do I? Where? the Naca chart shows the elliptical winged Spit has an advantage over the Mustang up to 260 mph IAS.

That could well indicate "the advantage tends to be with the Spitfire"

An advantage under 160 mph IAS wouldn't.

- Which only makes be believe what seems to be
- evident: tests made by the British are inconsistent
- with themselves, biased in wording, and unreliable.
- The Brits say that the Spitfire looses to the
- Tempest in roll at the very same airspeed as the
- 109; yet they describe 109 vs. Spit roll rate as if
- the Spitfire would have advantage at all speeds...
- funny.

Not at all. The Spit was better below 300, the 109 the same. Above 350, the Tempest was better than both, which doesn't mean the 109 was as good as the Spit.

- Whereas in
- case of foreign planes the phrase is always some
- kind of "all out superiority " of British aircraft,
- when comparing domestic a/c vs. domestic a/c, they
- suddenly go very nice and soft.

When comparing enemy aircraft, you are comparing enemies. When comparing your own aircraft against each other, you are comparing planes that will not fight each other. The same tone is used with the P-51.

Also, the same tone is used when they were comparing the 190 against the Spit V:

"The climb of the Fw190 is superior at all heights"

Dives - "the Fw190 leaves the Spitfire with ease"

Manoeuverability - "The Fw190 is better except in turning circles" "The Fw190 has better acceleration under all conditions of flight"

Even against the Spit XIV, when a German plane was better, they say so, in unequivicol language:

Rate of Roll
42. The FW 190 is very much better.

- that AFDU seemingly has no idea on even such a
- simple question what a rated altitude a DB 605A-1 in
- Bf 109G has (they give totally wrong number of 16.4k
- ft. - yeah that`s right: for an early Emil, maybe

I've told you umpteen times before, the AFDU didn't test performance specs, they compared planes against each other. RAE and the A&AEE did hard numbers tests, and even then I doubt they were very interested in engine outputs of captured aircraft.

XyZspineZyX
10-07-2003, 11:10 PM
Huckebein_FW wrote:

- Keep in mind that P-47 also suffered quite severely
- from wing twist at high speeds, as reported by NACA.
-
- Therefore using 15% deviation at 400mph for Bf-109
- which did not have this problems (until transonic
- range) most probably will give results below the
- real value of roll rate at that speed.


Which NACA report states the P-47 suffered "severely" from wing twist at high speed?

Keep in mind that the term "high speed" is highly subjective. High speed for the the Bf-109 was not high speed for the P-47, P-51 or Spitfire. The Bf-109F had a terminal speed of just over 900 km/h, and a do not exceed speed of 750km/h. While later '109 models could reach relatively high level speeds, they should not be considered any kind of high speed fighters.



- A 70deg/sec roll rate at 400mph is a very prudent
- value.

I would agree that 70 degrees per second could be achieved at 400 mph, it's certainly not an unreasonable number for more modern fighters like the P-51 and P-47. However, at what cost in effort? What was the stick force required to deflect the ailerons to achieve a 70 dps roll rate at 400 mph? I think this is the salient point most here would like to know, and you don't have the answer.

Regards,

SkyChimp

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XyZspineZyX
10-07-2003, 11:22 PM
hop2002 wrote:

- It's about half way down, a scan of a page from
- F4UDOA. Notice that these British figures are the
- ones accepted by Naca for the 190.
-
-- For example, the FW 190A showed here is the worst
-- roller of the 3 FW190As tested by the British; the
-- two others had considerably (+20-25deg/sec) higher
-- roll rate and lighter ailerons, still, the worst
-- performer was sent for some reason.


It's important to note that the F4U roll figures in the British report are not figures derived from actual British testing. They are figures provided by Vought.

And it's equally important to take into consideration that all we know is that these figures were achieved with stick force of *not more than* 50 lbs. That doesn't mean those are roll figures for a 50 lbs stick force. That could very well be a comparison of a Fw-190 at 50 lbs and a F4U at 20 lbs.

Take into consideration many F4Us were fitted and retrofitted with aileron boost tabs, and a Vought test pilot is quoted in AHT as staying the F4U could roll as fast as 180 dps. And I've personally see F4U-5s make 360 aileron rolls in 3 seconds.

Regards,

SkyChimp

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XyZspineZyX
10-07-2003, 11:28 PM
This is a new chart to me. I've seen the one for earlier P-38's without boosted ailerons and roll was moderate. These are truly outstanding high-speed roll rates.

http://members.cox.net/rowlandparks/boostroll.jpg


Regards,

SkyChimp

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XyZspineZyX
10-08-2003, 12:45 PM
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