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EnGaurde
09-30-2005, 07:58 PM
ive been having a dig around at freely available aerodynamics info online to try and determine how crucial wing design was on all the aicraft simulated here.

and it was interesting indeed.

one aircraft most of all held my interest: the mustang.

it seems the p51s range and speed were largely due to changing the way the air flowed across the wing, or more so stuck to it: the widely known laminar flow.

of course this may be all taken for granted by many, i had heard of the design but i never actually understood just what laminar flow was.

a wing creates lift depending on its design characteristics, and crucially drag also relies on this design effort.

it seems the p51 benefitted greatly from reducing the drag involved in creating lift, induced drag, by designing an aerofoil profile that kept the flow stuck to the top surface of the wing for as long as possible to avoid boundary separation, which created the induced drag and robs the aircraft of speed and range.

the p51D root profile:

http://i9.photobucket.com/albums/a57/engaurde/p51droot.gif

and the subsequent tip profile that has all the answers:

http://i9.photobucket.com/albums/a57/engaurde/p51dtip.gif

that flatter, smoother top surface apparently is the reason the p51 had great range and speed. Induced drag (caused by boundary layer separation of the airflow away from the surface of the wing), the byproduct of creating lift, was reduced greatly as a result.

this link: aerofoil shapes (http://www.ae.uiuc.edu/m-selig/ads/coord_database.html) has a huge selection of wing profiles if youre interested in having a look at why various aircraft fly like they do.

i couldnt understand, in my immense aircraft design experience http://forums.ubi.com/images/smilies/16x16_smiley-wink.gif, how Willy Messerschmidt gave his 109 a wing that did not have reduced drag characrteristics to offset a poor endurance, nor lower loading and gentle stall behaviour to maintain the edge over the Spitfire. Spring loaded slats were a poor substitute, and may have contributed to loss of control due to one deploying when the other didnt.

Also, from what i can dig up, the FW190 had a wing that seemed to enhance roll, and nothing else.

It seems to me that the american and british designers won thru superior understanding of what an aircraft would need to fulfil its role.

what would have happened if the 109 had a laminar flow wing back in BoB days? Or the Fw190 had a lower wing loading and stall characteristics bred out of it at the start?

food for thought.

EnGaurde
09-30-2005, 07:58 PM
ive been having a dig around at freely available aerodynamics info online to try and determine how crucial wing design was on all the aicraft simulated here.

and it was interesting indeed.

one aircraft most of all held my interest: the mustang.

it seems the p51s range and speed were largely due to changing the way the air flowed across the wing, or more so stuck to it: the widely known laminar flow.

of course this may be all taken for granted by many, i had heard of the design but i never actually understood just what laminar flow was.

a wing creates lift depending on its design characteristics, and crucially drag also relies on this design effort.

it seems the p51 benefitted greatly from reducing the drag involved in creating lift, induced drag, by designing an aerofoil profile that kept the flow stuck to the top surface of the wing for as long as possible to avoid boundary separation, which created the induced drag and robs the aircraft of speed and range.

the p51D root profile:

http://i9.photobucket.com/albums/a57/engaurde/p51droot.gif

and the subsequent tip profile that has all the answers:

http://i9.photobucket.com/albums/a57/engaurde/p51dtip.gif

that flatter, smoother top surface apparently is the reason the p51 had great range and speed. Induced drag (caused by boundary layer separation of the airflow away from the surface of the wing), the byproduct of creating lift, was reduced greatly as a result.

this link: aerofoil shapes (http://www.ae.uiuc.edu/m-selig/ads/coord_database.html) has a huge selection of wing profiles if youre interested in having a look at why various aircraft fly like they do.

i couldnt understand, in my immense aircraft design experience http://forums.ubi.com/images/smilies/16x16_smiley-wink.gif, how Willy Messerschmidt gave his 109 a wing that did not have reduced drag characrteristics to offset a poor endurance, nor lower loading and gentle stall behaviour to maintain the edge over the Spitfire. Spring loaded slats were a poor substitute, and may have contributed to loss of control due to one deploying when the other didnt.

Also, from what i can dig up, the FW190 had a wing that seemed to enhance roll, and nothing else.

It seems to me that the american and british designers won thru superior understanding of what an aircraft would need to fulfil its role.

what would have happened if the 109 had a laminar flow wing back in BoB days? Or the Fw190 had a lower wing loading and stall characteristics bred out of it at the start?

food for thought.

3.JG51_BigBear
09-30-2005, 09:49 PM
When the 109 first went into development it was a revolutionary design. The Germans were scaring the **** out of the rest of the world with that thing. I mean its not often that a modified version of a country's front line fighter holds the record for the fastest airplane in the world (the plane was highly modified but I don't think too many people knew that http://forums.ubi.com/images/smilies/16x16_smiley-wink.gif). Hitler also didn't envision going to war until 1945-46 so the Me109 was never meant to be the fighter Germany would go into battle with. Even when Germany ended up in combat with the 109 it was still going to replace it with the FW190. The G model only went into production to fill in the shortage left by lagging Focke Wulf production. Luftwaffe high command was expecting to phase the 109 out completely if not for the attacks on Bremen.

As for the Focke Wulf, again that thing was a very foward thinking design in a lot of ways. The reason the Focke Wulf ended up with the wing it got was a result of Kurt Tank trying to maximize control harmony. The wing's design and position gave it very light ailerons, moderate elevators, and stiff rudder control. Almost all accounts of test pilots I've read, describe this setup as being optimal for a fighter and gunnery platform. The Focke Wulf also featured the first real clear-vision, sort of buble canopy in Europe. It had very advanced automatic systems and was extremely heavily armed for something its size.

The P-51 seems to have been a result of hapenstance and luck more than anything else. Don't get me wrong, I'm an American born and raised and I do love this country, but some times luck is the only thing getting us through. The P-51 was a glorified P-40. Its design was about as backwards thinking as anything else. It was using an antiquated aircraft engine, it was designed for a job already being fulfilled by competant desings already in existance, and was created primarily because North American Aircraft Company didn't want to produce another company's fighter. Its wing was awesome and its design was solid but if the Brits hadn't have thrown a Merlin in that puppy it would have been banished to a life of recon and fighter-bombing as P-47s and P-38s kept up the escort role. Even then who knows if the Mustang would have ended up in American service at all if it hadn't have been for a brash officer who decided to go on his own initiative and keep a couple from the British order for USAAF trials.

I'm not saying the Stang wasn't a great design, and I'm certainly not saying the German fighters were infallible but I don't know if you can really credit the Yanks or the Brits with any greater incite than anyone else.

TX-Gunslinger
10-01-2005, 12:28 AM
With respect to the FW - the rate of roll has a significant amount to do with the size of the aileron surfaces relative to the rest of the wing.

What would be interesting is an analysis of the characteristics of the P-51 wing vs the FW wing design. These wings are somewhat similar, I think. The clues would be found in the NACA wing types for both. If I get time this weekend (or hopefully if someone who knows more than me shows up) I'll try to look it up on the NACA site.

I would actually say that the P-51's gas tank won the war. The wings were incidental. Good post.

S~

tomtheyak
10-01-2005, 06:38 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">
The P-51 seems to have been a result of hapenstance and luck
</div></BLOCKQUOTE>

Okay, I will give you that... RAF ask for P-40s, Schumed just happens to have an idea for a fighter knocking around in the office that the company won't back cos theres no-one to buy it.....

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">
The P-51 was a glorified P-40. Its design was about as backwards thinking as anything else.

</div></BLOCKQUOTE>

Absolute trash. The P-51 was the only piston fighter during WW2 to be designed from scratch with lessons having been learned in Europe being incorporated into the design. Aerodynamically was the most advanced fighter, probably even more so then the Me262! (note, semi-joke...)
Crikey the rad design using the meredith effect was amazing - the thrust generated by controlling the heat jet was actaully more than the drag of the radiator housing - aerodynamically the housing did not exist.
Yes the engine wasn't great but US did not have any hi alt engines at the time.

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">
I'm not saying the Stang wasn't a great design, and I'm certainly not saying the German fighters were infallible but I don't know if you can really credit the Yanks or the Brits with any greater incite than anyone else. </div></BLOCKQUOTE>

Yeah, we both agree - fact is as with so much in life theres always more than one solution to a problem and different designers prefer different approaches with respect to the 'ethics' on combat tactics of their parent Air Force. Think there was some pretty great leaps in thinking by all sides in all areas during the conflict - funny, but without WW2 i doubt the moon landings would have happened; at least not so soon....

IL2-chuter
10-01-2005, 02:11 PM
When the Allison was operated the way the British used it (no manifold pop-off valve) the engine pulled the Mustang along down low faster than anything else which is why the Allison Mustang was used for low altitude TacRcn through the war. Engine life was never reduced to Merlin levels (by a margin), it started everytime, and got better mileage and was smoother than the Merlin. It simply had an artificially low boost limit and no multi-speed blower. Even today many pilots (yep, I'm speaking for everyone http://forums.ubi.com/images/smilies/16x16_smiley-happy.gif) prefer flying the Allison to the Merlin, not counting the rest of the plane.

As far as completely phasing out the 109 in '42 . . . a number of influential pilots (i.e. aces) weren't enthusiastic about the 190 (although a few were) and no doubt mitigated that idea before (or besides) any interuption of 190 production. The 190 basically conceeded an altitude advantage to the West. Both types were, in fact, needed.

Happenstance and luck? Any designer works with the technology at hand (which may or may not be fully understood) and makes largely known compromises. This was a trial and error era in aviation but the laminar wing was fairly well tested by this time and North American felt it was ready to apply to a combat type. They knew what they were doing, duh. The Allison was stipulated by the Brits. A glorified P-40? Which would you rather have? All sides were ratcheting up the knowledge base a bit at a time, but as a package, the Mustang was a big single step.