reverse swept wing stress

[Alexy]

Do the reverse swept wings of the X-29 and su-47 affect the stress on the airframe.
In other words, do swept forward wings cause more or less stress on the airframe of a fighter during level flight at high speed.
I would appreciate links to sights relating to my question as well as answers themselves.

[johnsteele]

If you can give me more specifics of your project I could perhaps be more helpful. Is your project designed to answer the questions you pose?

The general references I found were Bruhn's "Analysis and Design of Flight Vehicle Structures" or Niu's "Airframe Stress Analysis and Sizing" ISBN 962-7128-08-2 or similar.

[ghariman]

Hi Alexy,

I did a search on the web and found this nice site on "swept wings":
http://en.wikipedia.org/wiki/Swept_wing

Star there and you should learn more about them and then hopefully get the answer to your question.

[crudshoveller]

Further to the forward wing-sweep question – the X29 had several forerunners all using this unconventional configuration. One is the successful, though rather pedestrian, Schleicher KA-7 sailplane.

The commercial venture HFB 320 Hansa Jet is another. A benefit of the forward sweep of the mainplane in this case was to allow a wing-spar penetration of the fuselage aft of the passenger cabin, thus more room for passengers. Otherwise the particular swept wing benefit is in the area of maintenance of good lateral control close to the stall. The feared aeroelastic penalties of the arrangement, such as the outboard deformation of the wing at speed, seems to have been readily overcome in aircraft of this type, the ones that eventually flew that is, by careful attention to the structural design of the wing.

One of the best-known forward swept designs was the four-engined Junkers 287 high-speed jet bomber which first flew 16 Aug 1944 (utilising twin nosewheels salvaged from downed B24s). The aircraft made 17 successful test flights and later flew in the Soviet Union (1947).

There were also other forward swept proposals during the war – the Blohm & Voss P209/02 for instance - a proposal which did not proceed beyond the early design stage. Interestingly the same company did some initial work on a swivel wing aircraft too, the P202. It was to have used twin BMW 109-003 turbojets (1944). The concept was later resurrected in the US Ames AD-1 aircraft (1979).

Focke-Wulf had an early proposal (December 1942) for a forward-swept design of fighter with a single turbojet mounted above the fuselage, in the same manner as the He 162.

There was also an advanced piston-engine fighter design proposal with forward-swept wing, the Heinkel P1076, based on the He 100 – and it would have used the same surface-evaporation cooling system. With the supercharged DB603M this aircraft was projected to attain 534mph at 36,000 ft (and 546mph with the more powerful DB603N).

Lots of interesting might-have-beens.

[soundwave990]

hey alexy

i have found some info at the us centennial flight commision website and and image from nasa if you havnt gone there yet...here are the links

http://www.centennialofflight.gov/essay ... /Tech9.htm

http://www.nasa.gov/centers/dryden/news ... opup2.html