How do fighter jets stay airborne when upside down?

[LURCH]

The X-29 also greatly reduced turbulence in the trans-sonic envelope. But by the time these experiments began, most fighter aircraft were already "negatively stable". AFAIK, the F-16 Falcon (first prototype flew in 1975, I believe) was the first fighter aircraft to have the center of gravity behind the center of rotation, and therefore the first aircraft that had to be flown by computer control, earning it its nickname; "the electric jet".

 

[Danger]

Fred, I didn't read your link, but looked at it. If memory serves, the pictures that you posted are the Northrope contribution, which was a modified F-20 Tiger Shark (which was itself a modified F-5 Freedom Fighter). General Dynamics had a similar beast, which was essentially an F-16 with the wings on backwards. Grumman had one that was 'purpose-built' from the ground up, but I can't remember much about it.

 

[AlephZero]

historically, designers had always worked towards greater stability in aircraft, making them easier to control. But stability is the antithesis of manouverability, since craft that is very stable will fight rapid changes in flight direction.

Is this basically right?

The engineering is right, though the history is a bit off. Some of the first people to realize that stability and manouverability opposed each other were the Wright brothers. By design, their planes required constant human control input for stability.

Not all the early designs got the stability/manouverability balance right. The (in)famous "Flying Flea" (designed 1930 and possibly the first home-build aircraft kit) was unfortunately very stable in the stalled configuration. The control surfaces were sitting in the stalled airflow, which was not a good design concept. Few pilots ever succeeded in recovering from a stall

 

[FredGarvin]

Fred, I didn't read your link, but looked at it. If memory serves, the pictures that you posted are the Northrope contribution, which was a modified F-20 Tiger Shark (which was itself a modified F-5 Freedom Fighter). General Dynamics had a similar beast, which was essentially an F-16 with the wings on backwards. Grumman had one that was 'purpose-built' from the ground up, but I can't remember much about it.

I'm drawing a total blank on the F-16 version. Do you have any links? The only modified test version of an F-16 that I can recall is the delta wing version, the XL.

 

[Cyrus]

http://www.f-16.net/f-16_versions_article26.html

 

[Danger]

Thanks for the link, Cyrus. I was going by a Popular Science article that I read about 25 years ago. I never realized that the F-16 wasn't actually built.

 

[DaveC426913]

Not all the early designs got the stability/manouverability balance right. The (in)famous "Flying Flea" (designed 1930 and possibly the first home-build aircraft kit)

Sigh. I decided to Google "Flying Flea designed 1930". Guess what was the https://www.physicsforums.com/showpost.php?p=1191095&postcount=33".


S'OK, http://www.valkyrie.net/~flyingflea/gallery.html".

 

[FredGarvin]

Now that I see this picture I vaguely recall seeing it before. It seems like it was 25 years ago.