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View Full Version : Aircraft with lowest drag figure......Witch one is it??



FA_Whisky
12-08-2005, 11:55 PM
Just let me know what you guys think. I think the Mustang series should have the lowest drag figure. Got no proof, but it looks the most airodynamic of all aircraft in the game.

Waldo.Pepper
12-09-2005, 12:10 AM
Me-163b Komet.

What do I win?

HayateAce
12-09-2005, 12:24 AM
He said "aircraft" not "Bloated Pop Bottle Rocket."


Me163 Comet prototype tested in hitler's back lawn:

http://www.e-scoutcraft.com/activities/bottle_rocket.jpg

fighter_966
12-09-2005, 01:03 AM
Whirlie or Fw190 of course ..Hard to decide which one

Waldo.Pepper
12-09-2005, 01:08 AM
Alright He-162 then (even with the engine on its back) I bet it has a lower drag coefficent than the Mustang.

fighter_966
12-09-2005, 01:11 AM
Originally posted by fighter_966:
Whirlie or Fw190 of course ..Hard to decide which one
Anyway Mustang in that picture does not have any drag http://forums.ubi.com/images/smilies/25.gif

joeap
12-09-2005, 01:14 AM
Originally posted by fighter_966:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by fighter_966:
Whirlie or Fw190 of course ..Hard to decide which one
Anyway Mustang in that picture does not have any drag http://forums.ubi.com/images/smilies/25.gif </div></BLOCKQUOTE>


http://forums.ubi.com/images/smilies/16x16_smiley-very-happy.gif http://forums.ubi.com/images/smilies/88.gif

Vike
12-09-2005, 01:22 AM
Me109K and P-39 for me.

I think they both have the most flowing shape,compared to many others http://forums.ubi.com/images/smilies/16x16_smiley-happy.gif

WTE_Ibis
12-09-2005, 01:56 AM
Hard to beat.



http://premium1.uploadit.org/Ibissix//14502.jpg

MEGILE
12-09-2005, 04:23 AM
I-16

nakamura_kenji
12-09-2005, 04:24 AM
prop plane probab be p-63 jet he-162

robban75
12-09-2005, 04:38 AM
P-51B.

neural_dream
12-09-2005, 04:52 AM
I've no idea, but I'd say the Ki61, Shooting Star and P-63.
But the best should be the super-smooth Spitfires.

The Bf109 is VERY DRAGGY. That with the fact that it's very light accounts for its ability to brake and accelerate very quickly.

edit: oops. you're right nk http://forums.ubi.com/groupee_common/emoticons/icon_smile.gif.

nakamura_kenji
12-09-2005, 05:11 AM
ki-43 >_< you sure no mean ki-61?

p1ngu666
12-09-2005, 05:26 AM
mossie

stathem
12-09-2005, 05:28 AM
Tempest is pretty slippy...born slippy in fact.

WOLFMondo
12-09-2005, 05:54 AM
P51B or C, Tempest II probably or the Tempest V with the annular radiator. The mach number on the wing is second only to the Spitfire so even the V is very aerodynamic even with that large radiator.

LStarosta
12-09-2005, 06:22 AM
Go-229.

ForkTailedDevil
12-09-2005, 07:53 AM
MiG-3

Kocur_
12-09-2005, 08:57 AM
P-51 because of laminar flow wings, Fw190D because of limited wetted area of Fw190 plus inline engine:lower on the page, "Flat plate comparison" graph (http://www.anycities.com/user/j22/j22/aero.htm).

LEBillfish
12-09-2005, 09:56 AM
BI-1 http://forums.ubi.com/images/smilies/16x16_smiley-wink.gif

Stackhouse25th
12-09-2005, 11:13 AM
i-185

Stuka_G10
12-09-2005, 11:52 AM
V-1

Viper2005_
12-09-2005, 12:07 PM
You need to be more specific.

Remember that a brick at 0 knots has 0 drag.

If you mean drag coefficient, you still need to be more specific.

Do you mean drag at low or high mach number?
With lift or without?
How much lift?

Drag is a complicated business...

Tully__
12-09-2005, 05:04 PM
Originally posted by Viper2005_:
You need to be more specific.

Remember that a brick at 0 knots has 0 drag.

If you mean drag coefficient, you still need to be more specific.

Do you mean drag at low or high mach number?
With lift or without?
How much lift?

Drag is a complicated business...
http://forums.ubi.com/images/smilies/351.gif

russ.nl
12-09-2005, 05:44 PM
The Me-262, its shark like apperance with his flat belly and back shaped wings. It really was designed for speed with its airodynamics.
Or else, also a german plane, the Ho-229 with its ray like apperance. It's just a wing with internal engines.
The germans really looked at nature in there designes I think. (our best teacher ofcourse)

And for the prop planes. I think the late war bf-109, spitfire and p-51 are about equal. But the p-38 has the best airodynamics I think. Althow it's hard to compare because it has 2 engines.

hotspace
12-09-2005, 06:49 PM
Sopwith Camel = I've drunk too much beer tonight, so I don't really know the question until tomorrow morning at the earliest http://forums.ubi.com/images/smilies/351.gif

Hot Space

leeG727
12-09-2005, 07:01 PM
From ‚‚ā¨ŇďAmerica‚‚ā¨ôs Hundred Thousand‚‚ā¨¬Ě

Zero lift drag coefficient at moderate speeds
Fighter Cdo
P-51D .0176
P-39 .0217
P-63 .0203
P-40 .0242
F2A .0300
P-47 .0213
F4F .0253
F4U .0267
P-38 .0270
F6F .0272
P-61 .0244

RocketRobin__
12-09-2005, 09:12 PM
I figure the slick plane of the time was the prototype He 100D. Of course the skin cooling solution (with dozens of electric pumps) wasn't reliable enough for production fighter planes.

Then again, no combat Mustangs were ever built that actually had laminar flow wings. While the Mustang design called for laminar flow over parts of the wing surfaces, it was impossible to impliment that requirement in mass production.

Every novel concept looks great on paper.
Unfortunately, the world is not made of paper.

If I actually had to fight a real battle in a WW2 plane, I would be less concerned about finnicky things, like perfect airflow. I'd pick something with a massive lump of iron in the front and a nice and cozy, solid titanium chair to sit in.
While the Jug isn't particulary sexy to look at, I wouldn't be worried about such things when going into battle against automatic cannon. In fact, I expect I would shrevel up, as if I had just taken a nice long swim in Hudson's Bay. Still, this would not bother me in the least. Completing my mission would be paramount and I would focus on little else, or die.

Of course, survival concerns are of no importance during online play. I can fly stylish planes with flair and audacity and, even under the penalty of virtual death, I wake up in the same cozy bed the next morning.

Viper2005_
12-09-2005, 10:53 PM
I assume moderate speed is ~ 200 mph TAS @ 10,000 feet or less.

What was the airscrew doing in these tests?

Next question - power on or power off?

Power greatly complicates things. You've got the Meredith effect, scrubbing drag from propwash, exhaust thrust, torque, p-factor etc.

At the end of it all you've got to make a load of "accounting" decisions to decide what your drag is.

And then as soon as you change your Mach number, the drag number changes...

Drag is a complex business...

Gibbage1
12-09-2005, 11:22 PM
The P-80 had insanly low drag. Thats how it was able to beat the Me-262's top speed with just one engine. The engine pods on the 262 had huge drag, and same for the He-162. Me-163 was very low due to its design, but had lots of appendeges like the landing skid, prop gen in front and a bunch of other stuff hanging off. 109 had nasty drag, and even the K-4 could not fix it all. P-51 was most likley the best of the props, and Go-229 the best for the jets. If I remember, the P-80 had even lower drag then the P-51 in like the .0160's.

I would like to see the listed Cdo for the 109, and I am NOT talking Kurfy's calculated version. http://forums.ubi.com/groupee_common/emoticons/icon_rolleyes.gif

Viper2005_
12-09-2005, 11:45 PM
YP-80 was pretty clean at low mach numbers - but that's academic if compressibility limits your top speed...

Most WWII aircraft were limited by compressibility rather than by the convergence of their thrust and drag curves. [Me-163 would enter a "graveyard dive" at a Mach number slightly greater than 0.80 for example. It wasn't drag/thrust limited.]

And in combat their limits were even lower because "snaking" would degrade their ability to track before they ran the risk of overstressing the aircraft.

The fastest WWII fighter (in terms of Mach number and TAS) was the Spitfire. It was dived to M=0.89 by the RAe High Speed Flight.

Try that in any other fighter of the period and you'll most likely not live to talk about it (jets included).

However, it was not the least draggy aircraft of the war by any stretch of the imagination.

It just happened to have a high critical Mach number, so it could safely attain very high speeds when dived.

Post war a Spitfire pilot over Hong Kong is reputed to have attained M=0.92.

Level flight is of course a totally different ball game.

Drag is a complicated business...

Gibbage1
12-10-2005, 12:06 AM
I have heard a lot of stories about this .89M Spitfire. They all seem to share the same common factor. #1, it cant be verified, #2, it involved the pilot blacking out and #3, when the pilot recovered, his prop blades were gone, and he was in a climb. A bunch of people got around and asumed he survived a dive close to M .89. Test's done post-war proved beyond a shadow of a doubt that a prop aircraft simply CANT get that close to the sound barrier due to a simple factor. The prop!!!!

A lot of people point out that the Spit that supposidly hit .89 lost its prop and that how it got so fast. A human being has broken the sound barrier in freefall quite a few times, but once that human reached about 150,000 feet, friction from the wind took over and slowed him well below the speed of sound as air got more dense. An aircraft flying at 30,000 feet is facing a LOT denser air, and descending the air just gets more dense. I dont think any aircraft could brake the sound barrier in a dive at that altitude, or get close for that matter. Dont you think if it was that easy, it would of been done before Chuck had to brake it with a rocket in 1946?

I dont buy the almost supersonic Spitfire "story" for one moment.

darkhorizon11
12-10-2005, 12:33 AM
parasite, induced, or total?

Total I'd say the YP-80.

Gibbage1
12-10-2005, 01:54 AM
Originally posted by darkhorizon11:
parasite, induced, or total?

Total I'd say the YP-80.

Well if we include prototypes, we need to include the Go-229. A flying wing is the most efficiant possible aircraft design. No body, no tail surfaces, nothing. In fact, its too efficiant in the fact that at high speeds it produces too much lift. No flying wing has ever broken the sound barrier. Northrop did a LOT of test's of rocket powered wings (that looked like the Me-163) and found out that at high critical mock speed they got VERY unstable from producing to much lift. Me-163 could have NEVER of broken the sound barrier no matter what, unless its wings ripped off http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif

Gib

IL2-chuter
12-10-2005, 02:35 AM
Actually, I would guess that the outer wings of a flying wing are producing a slight amount of downforce . . . this might be necessary for pitch stability and would explain why all flying wings are swept. If this is the case then flying wings should have a relatively low wing loading compared to a comparable conventional plane's wing - however - a conventional plane's stab (horizontal) produces downforce equivelent to about 10% of the wing's lift. http://forums.ubi.com/images/smilies/16x16_smiley-indifferent.gif

Just musing . . . http://forums.ubi.com/images/smilies/16x16_smiley-happy.gif

Gibbage1
12-10-2005, 03:35 AM
Originally posted by IL2-chuter:
Actually, I would guess that the outer wings of a flying wing are producing a slight amount of downforce . . . this might be necessary for pitch stability and would explain why all flying wings are swept. If this is the case then flying wings should have a relatively low wing loading compared to a comparable conventional plane's wing - however - a conventional plane's stab (horizontal) produces downforce equivelent to about 10% of the wing's lift. http://forums.ubi.com/images/smilies/16x16_smiley-indifferent.gif

Just musing . . . http://forums.ubi.com/images/smilies/16x16_smiley-happy.gif

You may have something. After looking at my referances from when I modeled the Go-229 for the game, the wing profile does change as it gets to the tip, and in fact the wing tips are almost pointing down!

This feature is NOT on the B-35 or N9M, but the Northrop wings had a MUCH MUCH more advanced control system then the Gotha wing did. In fact, it was so advanced, they used it on the B-2 http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif

robban75
12-10-2005, 04:41 AM
Originally posted by Gibbage1:
After looking at my referances from when I modeled the Go-229 for the game, the wing profile does change as it gets to the tip, and in fact the wing tips are almost pointing down!


Are we talking about wingtwist? I don't remember the correct word for it in english, but, it means that the wing tip is meeting the airflow at a lower AoA than the inner most part of the wing. Because wings that are swept back stall at the wingtip, straight wings stall at the wingroot. So in order to avoid a wingtip stall for as long as possible, the wing is twisted.

You can see it on this F-16. The wingtip pylon is pointing downward.

http://www.aviacion.cl/images/F16/F16-06.jpg

Kocur_
12-10-2005, 05:14 AM
Originally posted by RocketRobin__:

Then again, no combat Mustangs were ever built that actually had laminar flow wings. While the Mustang design called for laminar flow over parts of the wing surfaces, it was impossible to impliment that requirement in mass production.

Every novel concept looks great on paper.
Unfortunately, the world is not made of paper.


Im affraid you are wrong here. It might have been so in early 1930s, but ten years later mass produced wings were very close to projected airfoils. Not perfect of course, as that cant be achieved, but P-51s wings were laminar in practical terms. If not - how would P-51 be so considerably faster than P-40s and Spitfires powered by the same engines?

There is another case of practical checking out possibility of mass producing laminar wings. When P-63 was designed, they of course wanted to establish if it could be produced with real-laminar wings. So they had set of P-63 wings produced on regular P-39 line, of course without telling workers about any speciality of those. Those wings were then tested in wind-tunnl and proved to have projeted features.

Kocur_
12-10-2005, 05:19 AM
Ah, so we are talking not only about planes for real men but also about "Jets are for kids" http://forums.ubi.com/groupee_common/emoticons/icon_smile.gif (Writing on a plate visible inside of front turret of Confederate Air Force's B-24 http://forums.ubi.com/groupee_common/emoticons/icon_biggrin.gif)

I would say P-80. Clean one, and again: laminar wings!

robban75
12-10-2005, 05:39 AM
Jets are for kids huh? Nowdays, sure. In the 50's, hardly. http://forums.ubi.com/groupee_common/emoticons/icon_biggrin.gif

Kurfurst__
12-10-2005, 07:47 AM
The zero lift drag coefficinet of the Bf 109 F-4 was Cd0 = 0,023 :

http://img18.imagevenue.com/loc1/th_716_109dragcoeff.jpg (http://img18.imagevenue.com/img.php?loc=loc1&image=716_109dragcoeff.jpg)
(click to enlarge)



Since these are coefficients relative to wing area, they have to be multiplied with wing area, to get the total drag :

The Bf 109F-K's wing area was 16.05m2, ca 173 sq.ft. If we apply the coeff of Cd0 = 0.023, we get an Equivalent flat plate area for the Bf 109F-4 as :

109F-4 drag = 177 sq.ft x (Cd0=0.023) = 3.98sq. feet.


The Mustang D's Cd0 is 0.0176, and the wing area was around 242 sq.ft, thus

P-51D drag = 242 sq.ft x (Cd0=0.0176) = 4.25sq. feet. The P-51B should be cleaner.

I have british doc with a drag coeff of the Spitfire V posted by Neil Stirling, which I can't find right now, but if my doesn't fail me, it was around .0235-.0240, which gives :

Spit MkV drag = 244 sq.ft x (Cd0=0.0235) = 5.74sq. feet.

It's pointless to go over the rest of the planes, since all have 0.023 or worser Cd0, and without exception, their wing area is greater, thus the final equivalent drag plate area will be greater, too.

Thus opinions expressed regarding the 'nasty drag' of the Bf 109 are baseless, unless we speak of the early version, but imho those couldn't be that bad at all, being one of the fastest planes of their era.

The 109G-2 is practically the same, it's almost exactly the same airframe - so much that the 109G's ersatzteiliste in fact only contains the parts that are different from 109F..

I own a doc from early 1944, that was created by Messerschmitt to make the aerodynamic changes between existing 109G variants an easy matter, and from the effect of any change in equipment can be derived. It lists the drag of tailwheels, radio antennas, bombs, gondolas etc.

From that the 109K's Cd0 can be established with good accuracy, taking into account the changes between the 109K and 109F-4, some items were missing, but I reckon it's roughly the same, as along with some very important refinements such as wheel well covers and completely retractable tailwheel, there was some smaller stuff giving some extra drag, but generally these were small imprortance, and arrived at some .022 for the 109K.
The G-6 with it's non-retractable tailwheel and HMG bulges, should be around .024.



It's important to note that Cd0s don't give much clue about 'cleanness', they are just coefficients of aircraft's equivalent flat plate area and wing area. They can be useful comparison of evolution between the same type (ie. between 109F and 109K), but not really between differt types, as there are so many things producing drag other than just the wings.

The zero-lift drag coefficient, although useful as a measure of comparative aerodynamic refinement, has a basic limitation because the coefficient is based on wing area, and, for a given wing area, many different fuselage and tail sizes may be employed. Thus, differences in zerolift drag coefficients may be interpreted as a difference in aerodynamic refinement when the difference may result from a significant difference in the ratio of wetted area to wing area.

Which brings us to that most NACA-inspired Cd values are relative to wing area only, which alone makes Cd - or aerodynamic quality - comparisons incompatible. Simply because the amount and percentage of the total drag created by the wings is very different on different designs, ie. a P-51`s wings may be responsible for 15% of the total drag, whears on a, say Spitfire, with very similiar wing area it can be as much as 30%. Yet, you compare ALL DRAG vs. only a selected area which doesn`t share the same "responsibility" for it on different designs.

This being said, we are already comparing incompatible things, and the whole comparision doesn`t makes much sense, unless you are comparing two planes that are exactly the same, EXPECT for their wings.


Comparing drag with speed/power isn't a good idea either, since propeller effiency can srew the results greatly, ie. if you put a better propellor on the very same airframe, and it will get faster... did the plane become cleaner, too? Some props were optimized for high altitude, and performed poorer at low altitude.

What I would like to see is the Cd0 for the Yak-3 and La-7. They were awfully fast compared to their engine outputs. I am rather sure that the Yak-3, which attaind 560kph is speed with a mere 1240 HP engine (it had rather small wings and clean lines), would be the smallest drag of all.

Kocur_
12-10-2005, 08:26 AM
Originally posted by Kurfurst__:
What I would like to see is the Cd0 for the Yak-3 and La-7. They were awfully fast compared to their engine outputs. I am rather sure that the Yak-3, which attaind 560kph is speed with a mere 1240 HP engine (it had rather small wings and clean lines), would be the smallest drag of all.

In both cases plywood wings skin was covered with glued-on fabric, which was further covered with simple putty and then polished. Dont think that putty survived long in the line units.

p1ngu666
12-10-2005, 08:36 AM
i think the high speed of yaks and la's is from less parasitic drag, like mossie http://forums.ubi.com/groupee_common/emoticons/icon_biggrin.gif

Gibbage1
12-10-2005, 02:13 PM
Originally posted by Kurfurst__:
arrived at some .022 for the 109K.


Cool. P-47 at .0213 is less draggy then the 109K!

Also, Kurfy, when figuring out the drag differances between the F4 and K4, did you note that the F4 had a VERY clean cowel? No MG bumps since it did not use the bigger MG13's? Also it seems (correct me if I am wrong) that the F4 had much smaller radiators and oil cooler? What about the big bumps over the wheel well on the wing with the K4? Did not exist on the F model.

I think the K4 was a big aerodynamic improvement over the G series, but all it had on the F series was the cockpit canopy, and wheel wells. It does contribute a lot, but your saying there was other things. I dont see them.

Vike
12-11-2005, 07:23 AM
Originally posted by Gibbage1:
Cool. P-47 at .0213 is less draggy then the 109K

Which model of P-47 exactly!? http://forums.ubi.com/groupee_common/emoticons/icon_eek.gif http://forums.ubi.com/groupee_common/emoticons/icon_confused.gif

http://perso.wanadoo.fr/VisorVike/images/boudinvolant.jpg

http://perso.wanadoo.fr/VisorVike/images/kurfurst.jpg

I'm not an engineer in aerodynamics at all but i feel doubtfull with your figures Gibbage... http://forums.ubi.com/images/smilies/16x16_smiley-wink.gif


Originally posted by Gibbage1:Also, Kurfy, when figuring out the drag differances between the F4 and K4, did you note that the F4 had a VERY clean cowel? No MG bumps since it did not use the bigger MG13's? Also it seems (correct me if I am wrong) that the F4 had much smaller radiators and oil cooler? What about the big bumps over the wheel well on the wing with the K4? Did not exist on the F model.

I think the K4 was a big aerodynamic improvement over the G series, but all it had on the F series was the cockpit canopy, and wheel wells. It does contribute a lot, but your saying there was other things. I dont see them.

Yes it is true,but iirc,the F4 has a thick shielded glass in front of its cockpit.
This glass is embedded into the 109K windscreen that can reduce drag efficiently,i think.

There is also the little space between the propeller and the engine hood which has a smoother shape on the K than on the F (no more bulge left)

And finally,there is the radio antenna pole,which is totally suppressed on the K. http://forums.ubi.com/images/smilies/16x16_smiley-wink.gif

@+

Kuna15
12-11-2005, 07:23 AM
Gotta be P-51. So Mustang will get my vote http://forums.ubi.com/groupee_common/emoticons/icon_smile.gif.

Aaron_GT
12-11-2005, 09:53 AM
Gibbage wrote:

I have heard a lot of stories about this .89M Spitfire. They all seem to share the same common factor. #1, it cant be verified,

The fact that a test occured can at least be verified. Due to instrumentation issues there is always some uncertainty in tests (hence some P47 pilots claiming to have broken the sound barrier, when it was just instrumentation). You are right about the prop coming off, though, but the airframe was capable of high mach, just not the prop.

Kocur wrote:

Im affraid you are wrong here. It might have been so in early 1930s, but ten years later mass produced wings were very close to projected airfoils. Not perfect of course, as that cant be achieved, but P-51s wings were laminar in practical terms.

This might have been the case for an unpainted P51B wing, although I am not sure even NA thought they were fully laminar, certainly other airforces didn't feel they were, but the P51D had a slightly thicker profile and with paint it was no longer fully laminar flow. Laminar flow wings were certainly the way to go (see Spiteful and Tempest too) just not necessarily fully achieved in service aircraft.

Aaron_GT
12-11-2005, 09:56 AM
Does anyone have any figures for the Cd0 of the Tempest II - it has to be up there with the P47, I would think. The Tempest V problem loses out due to the chin radiator (it was felt that the maintenance issues with regard to wing root radiators weren't worth the extra speed).

Slickun
12-11-2005, 10:19 AM
Somebody on one of these discussions once claimed that the cd could be arrived at by looking at the thrust of a plane,its weight vs its top speed.

For example, if a plane had a ton of thrust at a certain altitude, but wasn't as fast as another plane of about the same weight with less thrust, it was draggier.

The point was that even without official numbers a very good estimation could be made.

Point here is that the P-51 went very fast at a relatively high weight and not as much thrust, as contemporary planes. The Spit 14 for example. Not as heavy, more thrust, speed about as even as two planes can be. Draggier is about the only way to square this.

hop2002
12-11-2005, 10:55 AM
I have british doc with a drag coeff of the Spitfire V posted by Neil Stirling, which I can't find right now, but if my doesn't fail me, it was around .0235-.0240, which gives :

Spit MkV drag = 244 sq.ft x (Cd0=0.0235) = 5.74sq. feet.


0.0218 for the Spit V from the RAE drag doc.

244 sq/ft x 0.0218 = 5.32 sq/ft


Does anyone have any figures for the Cd0 of the Tempest II - it has to be up there with the P47, I would think. The Tempest V problem loses out due to the chin radiator (it was felt that the maintenance issues with regard to wing root radiators weren't worth the extra speed).

The Tempest V, according to the same RAE doc, was 0.0199 (the last digit is hard to read, but I think it's a 9)


I have heard a lot of stories about this .89M Spitfire. They all seem to share the same common factor. #1, it cant be verified,

Well, the RAE certainly thought it could be verified. They after all conducted many such tests, using a variety of aircraft.


#2, it involved the pilot blacking out

No, no mention of the pilot blacking out. I suspect you are talking about the anecdotal evidence about a PR Spitfire's inadvertent dive over Hong Kong, which wasn't instrumented, and the speeds only guessed at.

The RAE did extensive research into high speed flight, they carried out properly instrumented tests at up to mach 0.89 in the Spitfire.


when the pilot recovered, his prop blades were gone, and he was in a climb.

That seems to be mixing the Hong Kong incident with Martindales crash in a Spitfire during the RAE tests. Martindale suffered engine failure and his prop was ripped away.


A bunch of people got around and asumed he survived a dive close to M .89.

IIRC, they calculated (using a lot of assumptions) that he got close to mach 0.95, but that's not a figure anyone with any sense would consider reliable.

What the RAE did is tests at up to mach 0.89 (that we know of).


A lot of people point out that the Spit that supposidly hit .89 lost its prop and that how it got so fast.

No loss of prop involved in this flight:
http://images5.theimagehosting.com/TobinDive-small.jpg

That flight was carried out by a pilot called Tobin. The same aircraft was later involved in a crash when flown by squadron leader Martindale, that's when it lost it's prop.


Somebody on one of these discussions once claimed that the cd could be arrived at by looking at the thrust of a plane,its weight vs its top speed.

For example, if a plane had a ton of thrust at a certain altitude, but wasn't as fast as another plane of about the same weight with less thrust, it was draggier.


Yes. A plane accelerates when drag is less than thrust, when drag equals thrust, it has reached it's top speed. If two planes with the same engine and prop and intake have different speeds, then the slower one has higher drag.

The problem is it's rare to find two planes with exactly the same thrust at the same altitude, even two aircraft of the same type (critical altitude varies by up to a few thousand feet between identical aircraft models)


Point here is that the P-51 went very fast at a relatively high weight and not as much thrust, as contemporary planes. The Spit 14 for example. Not as heavy, more thrust, speed about as even as two planes can be. Draggier is about the only way to square this.

I don't think anyone would argue the P-51 had very low drag at most speeds, certainly lower than the Spitfire across most of the speed range.