Would late-WW2 fighters have benefited from swept wings?
I’m not talking about sweeping back the wings on a Polikarpov I-16 or some such goofiness. I’m talking about 1944 and later; Ta-152H or Spitfire Mk.XIV, along those lines.
I know they could nudge mach in a dive, and I know that props+mach don’t mix well. But how about in level flight at altitude? (Say, 8500 meters at 640 KPH) Would it have been more efficient for a late-war prop fighter to cruise at those speeds if they had swept-back (or even delta) wings? Is the prop creating so much drag that the benefit from swept wings would have been negated?
I don’t have any technical answer for you, but I will note that the 1949 T-28 Trojan (that had performance characteristics similar to WWII fighters) was a straight winged plane. In fact, the T-2 Buckeye, originally built in 1960, but only recently scheduled for retiremant, is a jet with straight wings (and performance speeds slightly higher than those of WWII fighters).
There are actually quite a few high-subsonic jet planes (including fighters) that have used straight wings with some success.
If the propellor creates any net drag on an airplane something is really wrong as they traditionally provide thrust.
Swept wings can be an advantage even at subsonic speeds but there is a pretty wide gap between the fastest propellor driven planes and mach 1. The propellor tips will hit mach one well before the airplane does.
IIRC the P-51 was one of the first planes with a relatively thin laminar flow airfoil. The low drag of this wing combined with lower weight than other fighters gave the P-51 enough efficiency to be able to escort bombers to Berlin and back.
After WWII there was little military research into pushing propellor driven planes faster since jets were going so much faster. Not a lot of examples of swept wings with a propellor but one unlimited racer has used the wings from a Learjet on a P-51 fuselage. The top planes remain slicked up P-51s like Strega and Dago Red which use basically the original wing with the tips chopped off and Grumman Bearcat Rare Bare which is more brute force with less emphasis on low drag.
Actually the late WWII aircraft were jets like the Messerschmit ME 262, Gloster Meteor and Lockheed P-80.
I doubt that any propellor driven aircraft would have its overall performance enhanced by swept wings.
The jets, maybe but I’m not sure the aerodynamics of high speed flight was well understood at the time. If a designer had proposed swept wings the resulting analysis and testing would probably have taken long enough that the war would have been over by the time the design was complete.
The Me-262 had swept wings which the Germans had studied quite extensively as they had delta wing experimental planes even before the war. The US used a lot of that knowledge after WWII. The P59, P80 and the Gloster Meteor did not have swept wings.
The Me-262 wing sweep was pretty slight, and remember that it was still a subsonic aircraft. The extra weight required for adequate structural stiffness of a swept wing seems to have been the deciding factor. Only later, with the B-47, was it understood that a wing could be relatively flexible and much lighter.
The basic idea is twofold:
For supersonic flight, keeping the wing inside the shock cone produced by the nose reduces drag by preventing secondary shock cone formation by the portion of the wing that extends outside it. WW2 planes wouldn’t have benefited, of course.
For subsonic flight, the effective chord of the wing (parallel to the airstream) is larger than the actual chord (at right angles to the leading edge) by the cosine of the sweep angle, allowing the same lift to be produced with less actual wing. That has to be traded against the extra structural weight needed if a delta shape (filling in the aft side, in effect) is used. Then you deal with higher friction drag instead. Nothing comes free.
I don’t want to get this thrown into GD ElvisL1ves, but I don’t think comparing the high aspect ratio wing of a B-47 with an fighter/bomber like the Me-262 is a valid one. I don’t think anyone has ever designed a fighter with intentionally flexible wings, swept or not.
My references on the ME 262 state that the swept wing was actually introduced in order to move the main landing gear back behind the centre of gravity when the design was changed from a taildragger to a tricycle gear aircraft. The aerodynamic advantages of the swept wing were minimal and recognized after the design change had already been made.
I doubt that there would have been any advantage to a swept wing at prop speeds, especially given the extra design and manufacturing complexity.
Thanks to all for the answers. I shoulda figured that Jerry would have been spanking out a swept-wing Fw-190D if it were feasible/superior. Not to mention, those late-war aircraft were pretty darned advanced in and of themselves.
It was the addition of drop tanks to carry extra fuel at the beginning of the flight that allowed the P-51 to escort bombers all the way to Berlin and back. The laminar design was excellent (as was the plane, overall), but the P-51 only got to Berlin two days before the P-47 (with the honor being handed to the 4th Fighter Group’s P-51s over the 56th Fighter Group’s P-47s because the 4th had seniority in the Theatre. The P-38 could fly farther than either of them.
[ /nitpick ]
There were some experimental swept-wing prop fighters. The Curtiss-Wright XP-55 Ascender was one. Designed as early as 1939, test-flown in 1943. So it’s not that the idea was unknown until the Germans came up with it, as the fact that it didn’t offer enough advantages for the costs it imposed.
External, auxilliary, droppable allowed the longer flights. However, the wing profile also made quite a difference.
For example, the Martin B-26 and the Douglas A-26 were approximately the same size and used the same engines. The A-26 had the same wing profile as the P-51 and was about 50 mph faster than the B-26 at the same cruising rpm and manifold pressure and had about 300 miles longer range.
Maybe, but the question was whether or not swept wings would have improved its performance. Of the 15 million people in service then probably 12 million never saw combat either but they are still WWII veterans.
Swept or delta wings will give a planed a higher top speed, but will reduce it’s manueverability. think of the F-14 Tomcat. it has the swept wings for faster supersonic flight, but when it engages into combat (see movie Topgun) the wings switch to a more straight wing design allowing for tighter turns etc.
It was prior to WWII that Jack Northrup came up with the idea of an all-wing aircraft, and it had swept-back wings. This was actually built during WWII, as the Northrup N9MB Flying Wing (also called the YB-49). Photos are available here.
Note that the modern B-2 stealth plane bears quite a resemblence to this 1930’s design! (Photos here.)