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View Full Version : Surface drag of Bf 109/Spitfire/Fw 190 compared to later P51/Tempest ect



mynameisroland
06-28-2007, 06:47 AM
There are plenty other examples of draggy airframes but why did the Germans for instance, allow what appears to be quite a poor surface finish to their fighters fuselages and wings? I see bumos, poorly closed joins, control balances, wheels without door covers, draggy rack design ect

All planes had compromises here and they but when visiting the Imperial War Museum you get to see a Spitfire I, a Fw 190 A8 and a P51 D up close. The clean surface finish of the P51 immediately stands out.

The smaller designs benefit from having a high thrust to weight ratio but this is partially offset by having increased drag. Things like operating from grass runways in poor conditions can be used as an excuse but from the widespread practice of waxing and polishing fighters to get the maxium performance from them I would suggest that fighter pilots would be happier with less drag even if it meant only a few mph increase in their top speed.

http://i7.photobucket.com/albums/y294/mynameisroland/ILA2006_Me109_rechts.jpg
http://i7.photobucket.com/albums/y294/mynameisroland/BF-109-side-wing-view.jpg
http://i7.photobucket.com/albums/y294/mynameisroland/G10.jpg
http://i7.photobucket.com/albums/y294/mynameisroland/detail_fw190a_01.jpg
http://i7.photobucket.com/albums/y294/mynameisroland/detail_fw190a_02.jpg
http://i7.photobucket.com/albums/y294/mynameisroland/detail_fw190a_05.jpg
http://i7.photobucket.com/albums/y294/mynameisroland/19-PS91588001.jpg
http://i7.photobucket.com/albums/y294/mynameisroland/526266270_8bc9ca9537.jpg
http://i7.photobucket.com/albums/y294/mynameisroland/800px-P-51_Imperial_War_Museum.jpg
http://i7.photobucket.com/albums/y294/mynameisroland/nv778tt-2.jpg
http://i7.photobucket.com/albums/y294/mynameisroland/nv778tm-3.jpg
http://i7.photobucket.com/albums/y294/mynameisroland/nv778tm-4.jpg

Xiolablu3
06-28-2007, 06:56 AM
The P51 and Tempest certainly stand out as very 'clean' looking.

The FW190 looks clean too.

Spitfire top/frame is OK but the bottom has a lot of lumps and bumps.

The late 109's look like they deserve the name Galland gave them 'The Bulge'. No doubt the early models look a lot cleaner.

badatflyski
06-28-2007, 06:56 AM
http://forums.ubi.com/images/smilies/88.gif

Just for you i will take pictures of the spit's rivets in the brussels museum with original 43' rivets! http://forums.ubi.com/images/smilies/34.gif

Anyway We wants charts! http://forums.ubi.com/images/smilies/touche.gif

Ratsack
06-28-2007, 07:04 AM
Is this a function of the histories of those particular examples? The German types would be captured, and perhaps not in the best nick.

I recall having read somewhere that the finish on German planes was still extremely high well into 1944. In fact, I think the quote was in relation to Milch and Speer trying to streamline production, and somebody complaining that the seats were still upholstered.

That's finish, but regarding the bumps and boils, I suspect that if the P-51 or Tempest had undergone ten years of accelerated development, they'd have the same case of warts the 109 got.


cheers,
Ratsack

JG53Frankyboy
06-28-2007, 07:08 AM
Originally posted by Ratsack:
.............
That's finish, but regarding the bumps and boils, I suspect that if the P-51 or Tempest had undergone ten years of accelerated development, they'd have the same case of warts the 109 got.


cheers,
Ratsack

that can still happend today: F-16I
http://www.israeli-weapons.com/weapons/aircraft/f-16i/F-16I.html

sorry for joking http://forums.ubi.com/groupee_common/emoticons/icon_smile.gif

mynameisroland
06-28-2007, 07:09 AM
Originally posted by Ratsack:
That's finish, but regarding the bumps and boils, I suspect that if the P-51 or Tempest had undergone ten years of accelerated development, they'd have the same case of warts the 109 got.
cheers,
Ratsack

But ofcourse using the logic displayed in the other thread these aircraft would display no ill traits for their lumps and bumps and increased weight.

Brain32
06-28-2007, 07:27 AM
Spitfire top/frame is OK but the bottom has a lot of lumps and bumps.

The late 109's look like they deserve the name Galland gave them 'The Bulge'. No doubt the early models look a lot cleaner.

Are you blind? Or you keep forgeting that Spitfire was overall larger than a 109? Those bulges on the Griffon engined Spitfire are larger than those on G6, the rear view mirror on top of the canopy reaaaaaaly gives it a clean look too, not to mention those nice bumps on the upper part of the wings too. On top of that a picture of K4,G10 or even G6AS with streamlined bulges is not here. Oh and let's not even look at the undersurface of a Spit...

mynameisroland
06-28-2007, 07:31 AM
Originally posted by Brain32:
Are you blind? Or you keep forgeting that Spitfire was overall larger than a 109? Those bulges on the Griffon engined Spitfire are larger than those on G6, the rear view mirror on top of the canopy reaaaaaaly gives it a clean look too, not to mention those nice bumps on the upper part of the wings too. On top of that a picture of K4,G10 or even G6AS with streamlined bulges is not here

Brain I am increasingly beginning to wonder whether you can read a full sentence or whether your concentration wanders after 2 or 3 words.

here I'll post the initial question of this thread once again and I'll put the important bit your missing in colour to help you notice it ok ?


Surface drag of Bf 109/ <span class="ev_code_YELLOW">Spitfire</span> /Fw 190 compared to later P51/Tempest ect

Now for additional help in explaining the topic I had positioned the <span class="ev_code_YELLOW">Spitfire</span> in the same draggy category as the Bf 109 and Fw 190, does that seem clear?

Oh and check out the 2nd image of the Bf 109 again it is a K4 - apparantly.

WOLFMondo
06-28-2007, 07:38 AM
Originally posted by Ratsack:

That's finish, but regarding the bumps and boils, I suspect that if the P-51 or Tempest had undergone ten years of accelerated development, they'd have the same case of warts the 109 got.


The Tempest is an oddball though but similar to the 109 in some respects. The 30's Hawker Hart shares things in its design with the Hurricane, the Hurricane with the Typhoon, the Typhoon with the Tempest and the Tempest with the Seafury. Think of it this way:
Hurricane = 108?
Typhoon = 109E
Tempest = 109F
Seafury = 109G/K

Although unlike the 109's, this family just gets more and more streamlined with less lumps and bumps.

Xiolablu3
06-28-2007, 07:39 AM
GUys, before you all go off on one, I am quite sure that Roland put up the Spitfire as an EXAMPLE of an unclean bottom. (Ooo-err)

Look at the size of the draggy radiators compared to the Bf109's tiny slits, its no real wonder that it doesnt overheat as much. (if the ingame model is correct)


I am quite sure that the FW190 was much cleaner than the Spitfire, or is it just that it had tiny stubby wings and the SPitfire had big wings that create more drag? (hence its better turn and climb and the FW190's better acceleration and top speed on a lower powered engine)

Bremspropeller
06-28-2007, 07:49 AM
I am quite sure that the FW190 was much cleaner than the Spitfire, or is it just that it had tiny stubby wings and the SPitfire had big wings that create more drag?


The Spit's wings are shaped elliptical which DEcreases the induced drag.
However, the overall aspect-ratio is lower that the 190's.
And then there's still the profile to be considered.

It's actually MUCH more complicated than just adding up the wetted surface and compare the figures.

Brain32
06-28-2007, 08:07 AM
Brain I am increasingly beginning to wonder whether you can read a full sentence or whether your concentration wanders after 2 or 3 words.
Nope, just too hasty when writing, didn't quote the post I was replying to.

Oh and check out the 2nd image of the Bf 109 again it is a K4 - apparantly.
Hard to say really but bad angle for judging airframe(flaps and gears dwon, slats out), but the third one(which did not load for me first time) is G10 I think http://forums.ubi.com/groupee_common/emoticons/icon_smile.gif

Whirlin_merlin
06-28-2007, 08:10 AM
Are you blind?

Classic from some one who didn't read the question properly. Edit: Oh not repling to that, strange cnat see anyone promoting the spit as an particularly clean ac.

Back OT.

The 109, spit etc were designed in 'peace' time for a possible war against possible enemies. Late planes were deigned during the war which I suspect would focus the mind somewhat on getting the best possible result. Also I suspect it had become apparent that any 'edge' was an 'edge'.

Kurfurst__
06-28-2007, 08:10 AM
Establishing surface drag based on photos. Rather unorthodox concept I must say.

Carry on.

mynameisroland
06-28-2007, 08:15 AM
Originally posted by Kurfurst__:
Establishing surface drag based on photos. Rather unorthodox concept I must say.

Carry on.

I know imagine using ones eyes to assess whether a surface is uneven or not?

Ratsack
06-28-2007, 08:15 AM
Originally posted by mynameisroland:
...

Oh and check out the 2nd image of the Bf 109 again it is a K4 - apparantly.

The first 109 looks like a pic I saw of a German-owned Buchon re-engined with a DB 605.

The second one is harder to pick, but the position of the DF loop gives it away as a Gustav rather than a K. The deep oil cooler and the bump on the lower cowl just below the exhausts suggest it's got a DB 605 D or similar in it. That would make it a G-10. However, it's not got the red legs of a MW50 equipped Gustav, but then again, I seriously doubt it ever carried that black tulip design, too. The paint job muddies the water a bit, but it's not impossible that the lower cowl came from another aircraft and we're looking at a white-bread G-6. My money is on a G-10.

The third one is a Buchon conversion to G-10 'standard', whatever that means. German owned, again.

cheers,
Ratsack

WOLFMondo
06-28-2007, 08:16 AM
Originally posted by mynameisroland:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Kurfurst__:
Establishing surface drag based on photos. Rather unorthodox concept I must say.

Carry on.

I know imagine using ones eyes to assess whether a surface is uneven or not? </div></BLOCKQUOTE>

http://somethingtoputhere.com/lolcat/img/inurdisc.jpg

Kurfurst__
06-28-2007, 08:21 AM
I find this 'Buchon conversion' thing amazing. It seems to imply that those are for some reason, not really 109s in some way - whereas the Buchon is nothing else but German produced, Bf 109G aiframes exported to Spain sans the engine to my best knowladge, making it's Spain's headache to fit those airframes with whatever engine they could find.

So what makes a WW2 German produced 109G airframe fitted with a Merlin and then re-fitted nowadays with a original DB 605 not a 'true' 109G (whatever that means)... I cannot imagine, nor why it gets emphasized so much.

Ratsack
06-28-2007, 08:35 AM
Originally posted by Kurfurst__:
... I cannot imagine, nor why it gets emphasized so much.

Because the Buchons are historic aircraft themselves, in their own right.

Ratsack

Bremspropeller
06-28-2007, 08:44 AM
Buchons have different wing layouts.
Some have boundary-layer fences. others don't.

This one has them:

http://perso.wanadoo.es/jbelena2/Galerias/Buchon/Buchon_01.jpg

Xiolablu3
06-28-2007, 08:44 AM
The first aircraft is beatiful, I want it :-


http://www.error-net.com/webhost/sts/ftp/privtommy/109g6.jpg

Its a BF109G6.

Imagine flying that around, coolness factor 11, mmmmm

I would prefer it even to the Me262 in the background.

faustnik
06-28-2007, 10:12 AM
Originally posted by mynameisroland:
But ofcourse using the logic displayed in the other thread these aircraft would display no ill traits for their lumps and bumps and increased weight.

Ummm, I think the logic some where trying to put forward in that thread was that all these designs suffered from weight creep. Some other posters were trying to say that one type magically didn't suffer, even though its relative weight increases were similar or even greater than others.

******************

I think finish qualtiy had a lot to do with the ground crews. Some US crews were known to constantly wax and polish their aircraft. If you look at the Fw190s of Jg26 in 1942 and 1943, you can see a mirror shine on them. I'm sure late in the war LW ground crews were more worried about dodging strafing P-51s than polishing Bf109s. I can't imagine RAF groundcrews making the finish on their Spitfires anything less than perfect (but maybe that's just my prejudiced stereotype).

Insuber
06-28-2007, 03:29 PM
I've read that the P51 received a thick layer of a special paint to cover rivets, joints etc and get that smooth surface. Is it true?

Regards,
Insuber

Cajun76
06-28-2007, 03:49 PM
Originally posted by Insuber:
I've read that the P51 received a thick layer of a special paint to cover rivets, joints etc and get that smooth surface. Is it true?

Regards,
Insuber

Perhaps your thinking of waxing the joints to fill in the gaps? Bare metal was the way of late war Merkin fighters.

Bremspropeller
06-28-2007, 04:19 PM
The 51 also had flushed rivets. Many other planes didn't.

luftluuver
06-28-2007, 04:23 PM
Originally posted by Cajun76:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Insuber:
I've read that the P51 received a thick layer of a special paint to cover rivets, joints etc and get that smooth surface. Is it true?

Regards,
Insuber

Perhaps your thinking of waxing the joints to fill in the gaps? Bare metal was the way of late war Merkin fighters. </div></BLOCKQUOTE>Yes the wing of the P-51 had a 'smoothing' layer applied prior to the application of the silver paint. There is a photo in the P-51 InAction book taken in the Dullas plant.

VW-IceFire
06-28-2007, 05:17 PM
Originally posted by Bremspropeller:
The 51 also had flushed rivets. Many other planes didn't.
Quite a few did...Spitfires had them in most places except where it was deemed no necessary. For instance they didn't use flushed rivets around the engine cowling areas (in some spots) because the gain was less than 1mph while using them in other areas was shown to gain something like 4-5mph when they went for initial testing with the Mark I. That pretty much defined the design for the rest of the models. I don't think flush mounting was rare...but it wasn't ubiquitous either.

I thought it was pretty neat that just a few minor changes to the way you put the things together makes a huge difference in terms of how fast a plane goes http://forums.ubi.com/groupee_common/emoticons/icon_smile.gif

I guess they were surprised at the time too. But I guess it adds up.

blakduk
06-28-2007, 05:50 PM
"There are plenty other examples of draggy airframes but why did the Germans for instance, allow what appears to be quite a poor surface finish to their fighters fuselages and wings? I see bumos, poorly closed joins, control balances, wheels without door covers, draggy rack design ect

All planes had compromises here and they but when visiting the Imperial War Museum you get to see a Spitfire I, a Fw 190 A8 and a P51 D up close. The clean surface finish of the P51 immediately stands out."

As i understand it a lot of the compromises in the designs, such as no wheel well covers, were due to operational concerns. Problems such as ice/mud build up outweighed the slight increase in top speed. P51's weren't expected to operate from rough strips.
The initial designs for AC such as the Spitfire were developed from racing planes- they had to figure out ways to squeeze weapons and armour into the shape they'd created. Elements like radiators were also added to later as horsepower increased and the greater need dictated greater cooling ability etc.
Later planes like the P51 were considered after significant lessons were learned from air combat in Europe- speed, power, armour, armament were give much greater consideration than maneuverability. Another factor for the P51 was the need much greater range- it needed to cruise at altitude for long periods, it couldnt afford to have excess drag. A short range fighter like the 109 just needed to get up quick, kill, and come back down- drag wasnt such as issue as they could afford to power past it.

When 109's and Spitfires were first designed airforces were still dominated by biplanes.
When P51's were designed the designers had a different benchmark to beat.

DIRTY-MAC
06-28-2007, 06:58 PM
read up on history.
The Tempest was. In my opinion,the fastest propplane in the sky 44/45

Sergio_101
06-28-2007, 07:13 PM
Surface finish is not always important!
Proper fitting of panels, fillets and
the fairing of control surfaces is.

An extreme example is the Convair B-58 Hustler.
Some areas of the skin are "pimpled" intentionaly.
This reduces drag in those areas!
The B-58 normally operated in a high Mach 1
speed regime.

All those bumps, warts and poorly fitted hard points
on a Bf-109 added to the drag, no doubt about it.

Sergio

Cajun76
06-28-2007, 11:31 PM
Originally posted by DIRTY-MAC:
read up on history.
The Tempest was. In my opinion,the fastest propplane in the sky 44/45

Perhaps at low altitude, but the Mustang, Mustang Mk III and late P-47D were all faster at alt than the Tempest Mk V, at least on paper.

Kettenhunde
06-29-2007, 07:15 AM
Lot of cultural prejudice in this thread.

The Germans were fully capable of testing and engineering their designs. Just as the other nations did as well.

http://www.onpoi.net/ah/pics/users/503_1183122801_mk108covers.jpg

All the best,

Crumpp

Xiolablu3
06-29-2007, 07:22 AM
Originally posted by Kettenhunde:
Lot of cultural prejudice in this thread.



Sorry mate but thats just rubbish.

The 262 would come under possibly the least draggy of ALL designs.

What is being compared is drag on the BF109, the earliest of all 'modern' prop planes in WW2, and the SPitfire which was just over a year later, and the FW190 which was a year later again.

I think you are seeing prejudice where there is none.

The Hurricane would be much more draggy than the ME109.

I think you and others are starting to see prejudice where there is none, and ANYTHING said bad about German designs is jumped on immediately by you and a few others.

Any comments or opinons by pilots on the handling of aircraft are ignored, even when they all point ot the same thing.

It also seems that you are suggesting there is little or no difference between early war designs such as the Bf109, SPitfire,FW190 and later war designs such as the Tempest/P51, which I think is pretty much wrong.

Kettenhunde
06-29-2007, 08:23 AM
Sorry mate but thats just rubbish.

It is not rubbish. It is the truth.

Why would German "bumps" effect the aircraft more than "British bumps"?

Only answer is cultural bias.

That is a fact.

All cultures tested their aircraft and made appropriate design changes to fit their needs.

Can you read the report I posted?

Probably not, and that is why your still continuing with your view.

The significance of the report is applicable to all designs. Changes were tested and very little was done to a design that did not improve it in a practical fashion. Anything else is rather myopic view and frankly nothing but cultural bias.

Facts are all of these designs, not matter what culture produced them, were built by design teams that very much knew what they were doing.

Much more so than the majority on these boards. That is not cruel, mean, or even unexpected. You are not engineers designing your perspective nations top line fighter. You are gamers playing a very fun and enjoyable game.

The logic any cultural would spend considerable time, money, and effort to change a design for the worse, just fails miserably. In order for that logic to be true, we must assume a long chain of incompetance which only leads to one conclusion, that culture is flawed.

All the best,

Crumpp

Kettenhunde
06-29-2007, 08:25 AM
What is being compared is drag on the BF109, the earliest of all 'modern' prop planes in WW2, and the SPitfire which was just over a year later, and the FW190 which was a year later again.

Why don't you just do the math???? Should I do it for you?

I will if you guys need me too.

All the best,

Crumpp

mbfRoy
06-29-2007, 08:31 AM
Originally posted by Kettenhunde:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Sorry mate but thats just rubbish.

It is not rubbish. It is the truth.

Why would German "bumps" effect the aircraft more than "British bumps"?
</div></BLOCKQUOTE>
Who is saying that?

Xiolablu3
06-29-2007, 11:52 AM
Crumpp you are missing my point.

I am saying you are seeing 'Cultural bias' where there is none.

I dont think anyone is saying that Germany could not develop designs which were 'low drag'. Anyone with half a brain can tell that Germany was often far ahead of other countries in its advanced designs and workmanship.

They are simply comparing early designs with the later designs. The Spitfire was put up as an example of a draggy bottom. (oo-er)

Its nothing to do with German vs British vs USA.

Its to do with the lumps and bumps on the Bf109 and Spitfire compared to the P51 and Tempest. (And include the Me262 in there too if you need a German one too)

mynameisroland
06-29-2007, 11:57 AM
Originally posted by Kettenhunde:

Why would German "bumps" effect the aircraft more than "British bumps"?

Only answer is cultural bias.

That is a fact.

Once again Crummp the cultural bias is brought to the thread by you.

If you can see past your Blue tinted spectacles you would see that I have placed the Spitfire in the lumpy corner with the Bf 109.

"British bumps" cause drag too but in the Tempests case the bumps are very few and far between when compared to a K4 or an A8, infact the only bumps I can see initially are for the 20mm gun breeches.

Xiolablu3
06-29-2007, 12:04 PM
Originally posted by Kettenhunde:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">What is being compared is drag on the BF109, the earliest of all 'modern' prop planes in WW2, and the SPitfire which was just over a year later, and the FW190 which was a year later again.

Why don't you just do the math???? Should I do it for you?

I will if you guys need me too.

</div></BLOCKQUOTE>

If you want to, might be interesting, but I think its missing the point of the thread.

Roland was asking why not much attention was paid to close fitting panels, open wheel wells, unflush rivets, on some types but not others when the knowledge about drag was there, but seemingly being ignored.

For example. Why not cover the WHOLE SPitfire wheel instead of just half of it when its in its well? Why even in 1943 are there still unretractable tail wheels on fighters? WHy all the spikey things hanging off the 109's wings and little unflush parts here and there?

He is asking why wasnt more effort made to make these things flush with the airframe like the P51 and the Tempest (include the 262 there if you want).

EDIT: Sorry ROland answered you before I posted this one

mynameisroland
06-29-2007, 12:13 PM
Originally posted by Kettenhunde:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">What is being compared is drag on the BF109, the earliest of all 'modern' prop planes in WW2, and the SPitfire which was just over a year later, and the FW190 which was a year later again.

Why don't you just do the math???? Should I do it for you?

I will if you guys need me too.

All the best,

Crumpp </div></BLOCKQUOTE>

If you could do the maths (how we say math) and add the kind of bumps and bulges found on the G6 to the Tempest Id be really interested in seeing how much it would reduce its maximum speed.

I reckon it would make a 15/20 mph difference if all things were considered.

faustnik
06-29-2007, 01:00 PM
Fw190 drag reduction with the D-13:

http://www.preservedaxisaircraft.com/Luftwaffe/fockewulf/images/Fw190D13.jpg

I think this was a big concern with all designers. Putting needed firepower on the aircraft was a bigger concern. If rockets were needed to take down a target, rocket rails were added. For bombs, you scab on bomb racks. Have to try to knock down B-17s, you shoehorn bigger guns into the plane. Delivering the required firepower was obviously priority #1.

Kettenhunde
06-29-2007, 03:28 PM
Why not cover the WHOLE SPitfire wheel instead of just half of it when its in its well? Why even in 1943 are there still unretractable tail wheels on fighters?

Rough field capability. The ability to operate out of unprepared field is a huge asset to a military aircraft. It allows them to have strateagic mobility.

Covering up the wheel means our gear is now vulnerable to fouling with mud and grass. This can cause the gear to fail to lock or release. Either way both the pilot and the airframe are at risk.

Same with a retracting tailwheel, it vulnerable to fouling. Retracting linkage weakens the gear so we have make our oleo's larger and the mechanism adds more weight.



WHy all the spikey things hanging off the 109's wings and little unflush parts here and there?

Increased capability. I am not sure what you mean by all the "spikey things" but just as we see with Mk 108 covers, airframes are modified to increase capability.

These modifications are not just "slapped" on the aircraft. They are design engineered for that aircraft with the ultimate goal of ensuring the new capability and the continuing capability to perform the job the aircraft was designed to do.


If you could do the maths (how we say math) and add the kind of bumps and bulges found on the G6 to the Tempest Id be really interested in seeing how much it would reduce its maximum speed.

I can certainly do a very reasonable SWAG and mathmatically give the Tempest the Bf-109G6 MG covers. This will not take too long.

I am working on a "zoom climb" performance sheet for another forum member. Let me get that knocked out and I will SWAG this for you.

All the best,

Crumpp

Insuber
06-29-2007, 04:22 PM
Originally posted by luftluuver:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Cajun76:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Insuber:
I've read that the P51 received a thick layer of a special paint to cover rivets, joints etc and get that smooth surface. Is it true?

Regards,
Insuber

Perhaps your thinking of waxing the joints to fill in the gaps? Bare metal was the way of late war Merkin fighters. </div></BLOCKQUOTE>Yes the wing of the P-51 had a 'smoothing' layer applied prior to the application of the silver paint. There is a photo in the P-51 InAction book taken in the Dullas plant. </div></BLOCKQUOTE>

THX LUFLUVER.

Insuber

Polyperhon
06-29-2007, 05:43 PM
Some guys talk here without having any engineering background,so be a bit careful..take in consideration the following facts

- Bf 109s were built in 6 factories, instead of e.g 2 in the case of P-51. Furthermore, in reality, especially late in the war,these were more than assembly plants and nothing much more than that, which means that the vast majority of parts was taken out of subcontractors, small most of them, even in artisan level.In the continuous bombing conditions these means that either the tolerance requirements couldn't be filled (is questionable if small companies that were producing anything else but aviation parts could had been up to the task), either that especially in late war-models tolerances were set-up in higher variations, so this could ensure that all the parts could fit between them.In practice this meant slight over-engineering (=heavier airframe) and bigger gaps between panels and fillets.Take a notice at the fact that new versions of US warplanes were not taken directly into war, but remained for a reasonable time in USA: Part of it had to do with the fact that all production flaws had to be adressed, including the surface fitting.You 're sure that of course this was not a problem in US warplanes? Wrong.In these times, before CNC machining existed,if you were going to high scale production a time to adjust production and reduce faults was always neccessary. As partial solution was the use of small parts with solid rivets everywhere (see F4F,F6F) but these degraded performance and by itself was not enough.Typhoon is another example was how long it can take to built something right.See the Spiteful case too.They were not able to meet the required quality standards of the laminar flow wing.Poor quality meant that in the bad, not up to spec examples the "dirty" parts of the aerofoil was contributing to its vicious stall characteristics.When they tried to lower the standards, the performance gain was marginal.

- The recyclying that the germans did a lot, especially with Bf 109s, was another factor of poor external finish.Old and damaged airframes were not unlikely to be fitted with parts from various sources that were not always fitting well together.Another plane that was recycled a lot and used in battle afterwards was the Hurricane, but possibly the fitting of a new fabric cover helped these planes looking almost as new after re-fitting.Instead recycled US planes were usually used for training.



- The smoothness of an airframe surface is partly based on the specific alloy. and in particular on its elastic deformation properties.A material with good elastic deformation properties can be easier be prepared/repaired/polished to be smoother.Look at this
http://upload.wikimedia.org/wikipedia/commons/d/d2/Ki-100-RAF-side.jpg

The thin and not elastic japanese surface alloys were marginally lighter but were creating this rough surface that, well, makes them look like they were made out of plastic.

- Again about Bf 109s, many features that were not helping streamlining were in fact present because this meant a simplified, easier and faster production rates.So 5.000 hours were enough for a Bf 109G-6, instead of 15.000 that were needed for a FIAT G.55. Another plane that followed that root was indeed the much misunderstood (and underated) P-40.

- I think one last factor is the fact that today we have hundreds of restored warbirds that are actually in a "show", concours condition.Actually some of them are rebuilt in a standard that is highly unlikely that were so good as new, neither it was possible to keep in such a condition during combat operations.Some people have the false idea that back in 1944 every P-51 pilot used to go to war with planes as good looking as this one

http://www.warbirdcollectibles.com/images/P-51C%20Musta...ermark%20-%20500.jpg (http://www.warbirdcollectibles.com/images/P-51C%20Mustang%205%20X%207%20color%20watermark%20-%20500.jpg)

Daiichidoku
06-29-2007, 06:05 PM
Originally posted by blakduk:
The initial designs for AC such as the Spitfire were developed from racing planes

schneider racers gave practical exp in moncoque fuselages, stressed skin, etc

they had NOTHING to do with the design of the spitfire in the least...




Originally posted by Xiola:
Why not cover the WHOLE SPitfire wheel instead of just half of it when its in its well?

prototype spit had full wheel doors

there was a weight reduction programme, that resulted in the deletion of wheels doors...after they found it made no difference to speed or handling, and only eased oleo fouling issues, they left it like as we know it now

Kettenhunde
06-29-2007, 08:28 PM
that resulted in the deletion of wheels doors...after they found it made no difference to speed or handling,

You would not happen to have more information on exactly what they did to the Spitfire would you?

http://www.onpoi.net/ah/pics/users/503_1183170193_wheelwells.jpg

All the best,

Crumpp

Xiolablu3
06-29-2007, 08:43 PM
Originally posted by Polyperhon:
So 5.000 hours were enough for a Bf 109G-6, instead of 15.000 that were needed for a FIAT G.55.


Thats quite incredible.

I have read that the Spitfire took 3 times the man hours to build that a 109 did.

Daiichidoku
06-29-2007, 08:54 PM
Originally posted by Kettenhunde:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">that resulted in the deletion of wheels doors...after they found it made no difference to speed or handling,

You would not happen to have more information on exactly what they did to the Spitfire would you?

http://www.onpoi.net/ah/pics/users/503_1183170193_wheelwells.jp

All the best,

Crumpp </div></BLOCKQUOTE>


of course. i try to only state things i know as fact, one way or another

price's "the spitfire story" ISBN 0-85368-861-3

"the undercarriage legs on K 5054 had hinged flaps at both the top and bottom, so that when the wheels were retracted the underside of the wing was completely lean. these flaps gave considerable trouble, however, and often failed to close properly. it was decided to remove them in turn and see what difference, if any, the ymade to flight performance. on the 18th [july] the top flaps were removed and flt.lt. Simmonds flew a series of accurate level speed tests. 'the observed figures,' Mansbridge noted [Mansbridge was the flt test director for K5054], 'withiin the accuracy of observation, do not appear different from those previously obtained.'
on the 24th flt lt. Simmonds flew speed runs with the lower wheel flaps removed and found that these, too, had no observable effect on performance. from then on, the top and bottom flaps were left off the a/c


ok.

well, clearly i muddled the weight saving thing...but ill look for that later, it may mention it...

certainly, a diff of a few kph may not be clear to a pilot eyeballin it...which seems to be the case here...

is that a calculated figure, i wonder, or results from testing?..the difference is so small as to possibly not being noticed "within accuracy of observation" lol

Kettenhunde
06-29-2007, 09:48 PM
is that a calculated figure, i wonder, or results from testing?..the difference is so small as to possibly not being noticed "within accuracy of observation" lol

Yep! That is exactly what is going on I think.

The NACA data is calculated from wind tunnel data of full scale runs. In other words they hung the actual aircraft in the tunnel to gather the data.

All the best,

Crumpp

M_Gunz
06-29-2007, 10:04 PM
Max heads for the finish line to see:

What of any of this changes anything of the performance charts or IL2 models.

Max will be waiting perhaps for a long, long time. Probably need extra big popcorn.

Kettenhunde
06-30-2007, 08:43 AM
If you could do the maths (how we say math) and add the kind of bumps and bulges found on the G6 to the Tempest Id be really interested in seeing how much it would reduce its maximum speed.

SWAG of equivalent change in parasitic drag from the Bf-109F4 to Bf-109G6 on the maximum Equivalent Airspeed Velocity of the Tempest V (+9) Sabre IIA:

Bf-109G6 Cd(p) = 0.028408

Bf-109F4 = 0.027359

3.69% increase in Dp

Tempest V Sabre IIA +9 = 0.016389

0.016389 * .0369 = .000604754
.000604754 + 0.016389 = .016993754

.016389*358.0508475psf*302ft^2 = 1772lbs

New Dp = 1772lbs*(.016993754/0.016389) = 1838lbs

Vs2 = SQRT [(1838lbs/1772lbs)*325KEAS^2] = 331KEAS

331KEAS 325KEAS = 6KEAS

325KEAS-6KEAS = 319KEAS

344.9525424*302*.016993754=1770lbs

~6.9mph speed loss for the Tempest.

All the best,

Crumpp

Xiolablu3
06-30-2007, 12:04 PM
Thats quite incredible.

Almost not worth bothering maing planes aerodynamic.

Kettenhunde
06-30-2007, 03:23 PM
Thats quite incredible.

Actually you would be surprised. Some of the easiest aircraft to fly have high drag. If the design has appropriate power, having high drag gives the pilot instant speed control.

As soon as you back off the throttle, the plane slows down. Give it throttle and it picks up speed quickly especially in the realm of neutral stability.

Not that low drag is bad. It's very good and you don't need as much power to do the same thing. However the lower the drag, the harder it becomes to precisely control the speed. To a fighter pilot, that means overshoots are a large concern. It also becomes more difficult to take advantage of the angles given in a fight. Low drag airplanes do not like to slow down.

All the best,

Crumpp

Dtools4fools
06-30-2007, 04:35 PM
Ahh, streamlined beauties...
beauty (http://www.cjbalm.com/auto-aero/aitem199.htm)

http://forums.ubi.com/images/smilies/inlove.gif
One of the amazing planes; absolutely dislike it with the chin and absolutely love it with the radial...

Another one, early war:
beauty II (http://www.cardarmy.ru/avia/ki43ha.htm)

Sleeeeeek and slender...
http://forums.ubi.com/images/smilies/heart.gif

Other ones I like:
109F (http://www.hi-ho.ne.jp/a1takeda/Bf109F.html)

Few more beauties out there for sure...

109-Spit-190-Mustang-Tempest oder seems to me logical order in streamlining, seems designers learned something over time...

****