Me262 vs. P-80

[Soren]

Koolkitty,

Laminar flow wings don't offer a better L/D ratio, they only reduce drag at the expense of an also reduced CLmax and critical AoA. Therefore laminar flow airfoils are not good for turnfighters as they display dangerous low AoA stalls with little to no warning and provide too little lift in turns compared to conventional airfoils. That is why nearly every modern fighter since WW2 either uses LE slats or flaps to move forward and increase the chamber of the wing in turns.

Glider,

First of all the sweep of the Me-262's wing is no more than 17.3 degree's, so I don't know how you came up with the idea that this considerably increased induced drag because of greater upwash, esp. when you consider that a high wing taper ratio, as that of the P-80's wing, has the exact same effect. So can I ask what's your point ?

Also the higher AR of the Me-262's wing more than makes up for the sweep of the wing in terms of reducing induced drag.

[Glider]

Originally Posted by Soren

Glider,

First of all the sweep of the Me-262's wing is no more than 17.3 degree's, so I don't know how you came up with the idea that this considerably increased induced drag because of greater upwash, esp. when you consider that a high wing taper ratio, as that of the P-80's wing, has the exact same effect. So can I ask what's your point ?

Also the higher AR of the Me-262's wing more than makes up for the sweep of the wing in terms of reducing induced drag.

Any swept wing suffers from increased induced drag, it cannot be avoided as its part of the dynamics. Straight wings don't have the same problem.
The increased drag comes from the greater upwash, its not my idea, its aerodynamics.

As for the higher AR of the 262 more than making up the difference of the increased induced drag, I don't know as it would need information I don't have and to be honest, I doubt if you have the information either.
The 262 doesn't have a significantly high AR, so my personal guess is that it wouldn't, but I admit that is a guess. If you have the detail to support your statement I am more than happy to go with your comment

Re the high wing taper ratio of the P80 having the same effect on the Induced Drag I agree. However, if the question is does it have a greater or lesser degree than the swept wing on the 262 again, I don't know.

[Soren]

Originally Posted by Glider

Any swept wing suffers from increased induced drag, it cannot be avoided as its part of the dynamics. Straight wings don't have the same problem.
The increased drag comes from the greater upwash, its not my idea, its aerodynamics.

Yes Glider its aerodynamics, and aerodynamics don't support your claim that induced drag is greatly increased with 17.3 degrees of sweep. Get my drift ?

As for the higher AR of the 262 more than making up the difference of the increased induced drag, I don't know as it would need information I don't have and to be honest, I doubt if you have the information either.

You may doubt it all you want but I do have that information Glider:

Cdi = (Cl^2) / (pi * AR * e)

Try plotting in some figures and see what effect just a 10% increase in AR actually has on induced drag.

The 262 doesn't have a significantly high AR, so my personal guess is that it wouldn't, but I admit that is a guess. If you have the detail to support your statement I am more than happy to go with your comment

Is 7.23 not high ? And thats without considering wing sweep.

Re the high wing taper ratio of the P80 having the same effect on the Induced Drag I agree. However, if the question is does it have a greater or lesser degree than the swept wing on the 262 again, I don't know.

Its very close to the same Glider.

[kool kitty89]

Both the P-80 and 262 used Laminar Flow airfoils though, right?

So both laminar flow and elliptical wings have dangerous stall characteristics, but elliptical wings would be better durring maneuvers, and tapered, high AR wings would be perfered except for roll-rate, and stictural strength issues...

With that in mind, the He 280 probably wouldn't have used a laminar flow airfoil. (one interesting thing with Heinkel fighters is that, short of an elliptical wing, a TE-tapered wing with straight LE was used, as seen in the He 100 and He 162)


And still, I've never seen a direct comparison between the maneuverabillity of the P-80 and Me 262, though the He 162, DH.100 Vampre, and certainly the He 280 were more agile, but that's a different story... (the Meteor Mk-4 was probably less maneuverable above 400-500 mph (depending on altitude) due to air-flow separation on the thick tail surfaces, rectified in the F-

[SoD Stitch]

Originally Posted by kool kitty89

Both the P-80 and 262 used Laminar Flow airfoils though, right?

Well, I know the Me 262 did not use a laminar-flow wing, it couldn't; the tolerances for a laminar-flow wing were, by 1944, beyond the capability of the German aircraft industry. You must have exceptionally high tolerances to properly build and maintain a laminar-flow wing and, frankly, the Germans were more concerned with simply completing airframes as fast as possible by '45, let alone completing them well. If you've ever looked at the surface of an Me 262 made after 1943, you can see what I mean; the finish was very rough, especially on the fuselage. The wings were somewhat better, but there were still countless rivets in the wing that weren't all that smooth. The Germans actually used tape on the fuselage seams were the various sheet metal panels joined in order to alleviate the roughness of the finish; you can see it in some of the photos of unpainted Me 262's captured during & after the War.

[kool kitty89]

Ok, and I'm pretty sure the P-80 used laminar flow wings. (the P-59 did too, but with wings that large and thick, 45.5ft span & 386 ft2 area, this canceled out any low drag benifits... Plus there was the general lack of streamling and wind-tunnel testing durring development; no wonder it ended up a lemon.)

It is interesting though, that no US jet-powered fighter has ever used external engine nacelles, the Airacomet was the closest they got, and even it had the engines incorporated into the wing-fusalage junction...

[Glider]

Originally Posted by Soren

Yes Glider its aerodynamics, and aerodynamics don't support your claim that induced drag is greatly increased with 17.3 degrees of sweep. Get my drift ?

Yep and the drag is increased to some degree

You may doubt it all you want but I do have that information Glider:

Cdi = (Cl^2) / (pi * AR * e)

Try plotting in some figures and see what effect just a 10% increase in AR actually has on induced drag.

Its the 'e' value thats missing for me. DO you know anywhere where these can be obtained? Its not just for this its something that I have looked for.

Is 7.23 not high ? And thats without considering wing sweep.

Nope, not when your used to figures of 16-25 Seriously, you are correct iro aircraft, my mistake.

Its very close to the same Glider.

I wouldn't disagree with this

[kool kitty89]

One thing the P-80 certainly had aganst it was the paint scheme, or lack there of. The bare aluminum would have been alot easier to spot than the 262's camo... Though all USAAF planes produced by this time were like this
since they were no longer trying to hide from the LW. Plus the original Pearl-Gray (still not camo) prooved to be too hard to maintain too... But the lack of paint saved a bit on weight ad drag...

Though in Korea this didn't make a difference since the migs were bare too...

[Soren]

Glider,

The only way to determine the Oswald Efficiency factor ('e') is with full scale windtunnel tests, so I therefore don't have the accurate figures here either. But e is often very similar between aircraft, esp. of the WW2 era, so I assume that the Me-262 and P-80 have rather similar e values.

Koolkitty,

The Me-262 didn't use laminar type airfoil.

Stitch,

The Germans were fully capable of making laminar flow airfoils, however being well aware of its negative effects on lift and stalling characteristics it was decided not to use it on any a/c.

[SoD Stitch]

Originally Posted by Soren

Stitch,

The Germans were fully capable of making laminar flow airfoils, however being well aware of its negative effects on lift and stalling characteristics it was decided not to use it on any a/c.

I'm sure the Germans were capable of building laminar-flow wings; they were capable of just about anything but, as you pointed out, the benefits did not outweigh the negatives, so it was decided not to pursue that line of development.

And, as I stated above, by the end of the War, the Germans were using any & every able bodied person, German or not, to produce war armaments; so the people assembling Me 262's weren't exactly of the highest caliber skill-wise.

[Soren]

Another reason for why the Germans did not implement the laminar flow airfoil into their designs was that actually achieving fully laminar flow over the wing was all but impossible back then. First of all the surfaces of the wing had to be kept in absolute perfect condition, no small lumbs or the laminar flow would by ruined, something which was impossible in the field - hence the P-51's in service didn't achieve a full laminar flow over their wings.

[syscom3]

The issue of laminar flow wings is the precise tooling needed to build the wings. Tolerances are critical.

NAA figured out a way to build them in a mass production environment. Germany didn't, thus they stayed with the more traditional wings.

[Soren]

Thats incorrect Syscom3, the Germans deliberately decided not to use laminar flow airfoils for their designs entirely because of its negative effects.

[Kurfürst]

Originally Posted by DerAdlerIstGelandet

I thought the one that crashed actually crashed up in England at RAF Burtonwood and killed Major Frederic Borsodi.

Hi,

Does anybody have any kind of biograpical data on Borsodi - pictures, aircraft he flew, service record etc? If so, please contact me in email or PM!

[delcyros]

Some Ho-IVb flying wings were build with a laminar flow wing and flying in mid 43. Laminar flow wings were considered for the improved Ta-152 and Do-335 but these projects were not carried out.
I too believe that tooling technology in Germany was not improved enough to allow their mass implementation by 44.
Laminar flow wings of otherwise comparable properties will stall both, earlier and more violently (often with direct translation from laminar to seperated flow, bypassing turbulent airflow). In a prolonged turn this is critical and gives the -262 a distinctive advantage (LE-slats furtherly delay the stall to higher AoA-figures).
But I really doubt this plays a role here. The -262 pilot who keeps turn maneuvering until LE-slats deploy will waste his "e" and thus becomes an easy target for others. Staying fast is what increases survivability chances. Turning is ww1 style fighting. The roll charackteristic is not affected by LE-slats and the roll behavior of the 262 cannot be better than the P-80 with all the mass of the engines placed so far outbordly, hands down.
Laminar flow wings do not only allow a lower drag figure but also structural improvements (the wing can be build more stiff or an equally stiff wing can be build lighter) and advantages in wing space (laminar flow wings allow larger wing fuel tanks, one of the major advantages of the P-51).
Finally some words to engine nacelle placements. Early jet engines delivered insufficiant thrust and thus designers had to reduce the AIR INTAKE and EXHOUST losses to optimize the low thrust powerplants. Tests with 6m intake
pipes and 2m exhoust pipes on a Me-262, carried out in feb. 45 for evaluation of the HG program, showed that the losses are 6% thrust for the intake and 3% thrust for the exhoust, respectively.
These intake / exhoust losses are often neglected in thrust / weight or powerload figures of embedded designs as in the P-80 / Vampire.
It is a tradeoff. external mounts (Meteor, He-162, Me-262, Ar-234) add drag but will allow 100% of the nominal thrust of the powerplant and internal mounts cannot always be made as perfect as in the short bodied Ho-IX.

best regards and a merry Christmas,