How much it can make sense to have a swept wing on a fighter that is otherwise a 'classic' ww2 fighter, piston-engined tail-dragger mostly? By what turn of speed or Mach number we'd see benefits? Granted, the low-speed handling needs to be addressed, too - with wing not being too small for the expected weight; application of then-known high-lift devices, etc.
Swept wing on a ww2 fighter with piston engine power?
- Thread starter tomo pauk
- Start date
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michaelmaltby
Colonel
Admiral Beez
Major
Just the odd fellows...
davparlr
Senior Master Sergeant
I'm not sure any ww2 aircraft, those using a propeller, would be able to obtain velocities, even in a dive, close enough to Mach for swept wings to really benefit. Obviously the P-38 had problems but I suspect the problem was from the fuselage and not the wings. Drag really goes up fast as an aircraft approaches Mach one. Even the swept wing Mig 15 was unable to obtain Mach one in a dive. The Tu-95 has propellers and swept wings but the power is massive and the propellers are supersonic.
swampyankee
Chief Master Sergeant
- 4,022
- Jun 25, 2013
Even the fastest WWII aircraft, possibly except the Me163, was too slow to benefit from sweep, and, yes, I'm including the Me262, which had sweep because they mucked up the c/g calculations.
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Delta wings are low aspect ratio wings and have the disadvantages and advantages of that but delta's add some advantages.
1 Low aspect ratio means relatively low Lift/Drag ratios, which is a disadvantage.
2 Contrasting the above is that delta can pull high angles of attack and generate high coefficients of lift because vortices from the wing roots keep the airflow attached. However the drag is high so this is not good for sustained turns unless backed by high engine power.
3 The delta is structurally simple and thick at the wing roots and has lots of internal space for fuel, undercarriage and even weapons. The light weight can be used to increase wing area which compensates for the low aspect ratio
4 Delta's are naturally stable and can be tail less.
5 I would think that any fighter or dive bomber made on the basis of a delta would have a high power to weight ratio but would be quite fast.
6 A delta would probably need either a saw tooth leading edge, wing fence or slat o the outer half of the wing to handle span wise flow. (edited)
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Admiral Beez
Major
Do forward swept wings make any more sense on prop aircraft? Like the Heinkel P.1076.
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From an aerodynamic point of view forward sweep is better than rearward sweep. This is because the span wise flow that sweep causes lengthens the distance the air travels and increase the chance of boundary layer separation and therefore stall at the tips where the ailerons are. If the span wise flow is inwards (as in a forward swept wing) the problem is less because a stall on the inboard section of the wing causes less problem (no loss of aileron control) in addition the fuselage forms a natural wing fence that blocks the span wise flow. You tend no to need fences, slats dog teeth etc on forward swept wing which keeps it clean.
From an structural and aeroelastic point of view a forward sweep requires a stiffer wing but that's not too bad if the sweep is not too much like P.1076. It would be a matter of twin spars and good skins.
Forward sweep also seems to increase forward visibility
From a layout point of view the forward sweep leaves lots of cabin space and bomb bay space ahead of the spars. The Ju 287 had lots of space for a bomb bay ahead of the sweep and it worked in the Hansa business jet.
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They didn't muck of the CoG calculations directly. The engine weight estimates for both BMW 003 and Jumo 004 were too low and the engines needed to be moved from the wing roots to outboard because they couldn't handle rough air.
The Mach limit increase is approximately 1/cosine(sweep). The sweep of the Me 262 was about 16 degrees at the quarter chord 1/cosine(16) = 1.04. So the Me 262 benefited by about 4% works out about 22 mph. Not much.
They did consider adding sweep for aerodynamic reasons at the early predesign stage but wanted to avoid the risk.
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Sweep doesn't cause spanwise flow. You get spanwise flow with unswept wings as well.
