kco@allegra.UUCP (09/20/84)
"Calverton, N.Y.- Hidden within the sleek skin of Grumman Aerospace Corp's X-29 prototype fighter is a triply redundant digital flight-control system. Without the computers, the plane would be virtually unflyable: its distinctive swept-forward wings, desined for rapid supersonic maneuvering, result in a plane that is as tricky to control as a 40-ton tractor-trailer speeding across an ice-covered bridge. ... " -excerpt from Electronics Week magazine, Sept 10, 1984, page 20
stevel@haddock.UUCP (09/24/84)
I wonder what the Germans did with thier forward swept wing planes
during WWII and just after. They had no computers to make it flyable.
Anybody know.
Steve Ludlum, decvax!yale-co!ima!stevel, {amd70|ihnp4!cbosgd}!ima!stevelknutson@ut-ngp.UUCP (Jim Knutson) (09/24/84)
Destabilizing an aircraft for improved performance is the latest leap in aircraft technology. Of course, the triple redundant control system is needed since a failure of a systems would make the aircraft impossible to control. NASA has also been doing similar research with canards. Using computer control, the canards can be used for side slipping followed by air brakes to ellude pursuing air craft and for flat turns allowing you to sight on a very fat banked target.
knutson@ut-ngp.UUCP (Jim Knutson) (09/25/84)
By the way, the forward sweep of the wings do not inherently make it a destable aircraft. It has more to do with center of gravity and center of pressure. The closer they get, the less stable the aircraft gets.
ron@BRL-TGR.ARPA (09/26/84)
From: Ron Natalie <ron@BRL-TGR.ARPA> I don't put much faith in Electronics Week. Last week they ran a picture talking about exports to Japan and the caption mentions "like this one from Cray." The picture shows a big black boxy machine which is a Denelcor HEP. Later in the same magazine they discuss how IBM is developing an array processor to be used in conjunction with their 3081 machine and that Sperry is doing similar for their 1108 processor. Great, now I know what they are doing with the old obsolete Univacx. -Ron
dpw@bonnie.UUCP (David P. Williams) (09/26/84)
With regard to forward-swept wings: The aeronautical engineers can put together an aircraft with forward-swept wings that is dynamically stable - witness numerous sailplanes, the Hansa corporate jet (made in Germany), and a bomber prototype the Germans were working on at the close of World War II. Advantages of a dynamically unstable aircraft are better maneuverability and tailoring of the response of the aircraft to different flight regimes. The F-16 and Space Shuttle are dynamically unstable and use different control responses depending on speed, angle of attack, and other facters. The penalty is that you have to maintain redundant control systems for safety. The X-29 is not a radically different aircraft for employing new wing technology and dynamic instability. For high speed aircraft, the big advantage of forward-swept wings is that separation of flow over the wing while maneuvering occurs at higher angles of attack than for conventional swept wings *if the wing can be kept from twisting under the load (aeroelastic divergence)*. Since steel and aluminum are more than happy to twist without a prohibitive amount of stiffening, forward-swept wings have not been usable until now. With graphite epoxy and other composites, wings can be tailored to bend and flex in specific ways by aligning the grain of the cloth and using varying numbers of layers. So, it is now practical to build aircraft with forward-swept wings - many of the designs for the Advanced Tactical Fighter (ATF) feature them along with canards for better maneuverability than the current generation of fighters. David Williams AT&T Bell Laboratories Whippany, NJ (bonnie!dpw)
knutson@ut-ngp.UUCP (Jim Knutson) (10/01/84)
Correct me if I'm wrong, but don't swept forward wings change the stall characteristics so that the stall starts at the root and works its way out? This allows you to keep the aircraft in control until a full stall develops.