Posted on 08/27/2014 8:31:43 AM PDT by Sergio
A question for the aviation buffs on this forum. I was told at one time, that the F-16 was an inherently unstable aircraft, and that without assistance from it computers, no human pilot would be able to fly the aircraft.
Then I saw this video, (see link below), of a quarter scale, radio controlled F-16, in the colors of the Royal Dutch Air Force demonstration team.
I would think that there is not enough room in the model or money in the owners bank account to include flight control computers. So my question is; How is the unstable F-16 model can fly so well without its flight computers?
https://www.youtube.com/watch?v=qQ9dSrrBN28
Yep, good catch, my bad. The Thunderbirds.
Can’t help but think about the Jimmy Stewart movie flight of the Phoenix.
It’s also deified in Israel!!
North American T-6 Texan engine, cowling, propeller, undercarriage wheels and cockpit controls Beechcraft C-45 Expeditor wings, North American L-17 Navion wheel used as the P-1's tailwheel. Tallmantz-designed and constructed fuselage, wing roots and skids.
"During filming on 8 July 1965, Mantz tried to simulate a takeoff by making a "touch-and-go". As Mantz came in for another low camera pass, his rate of descent at 90 mph exceeded the plane's structural capacity. The modest impact of the touchdown, coupled with the sudden drag caused by the aircraft's cobbled skid/wheel landing gear, caused the boom section behind the wings to fail, propelling the nose section forward, with the P-1 breaking up violently, killing Paul Mantz instantly.[2] Stuntman Billy Rose, also on board, was thrown clear and survived with a broken shoulder and pelvis."
Depends on the configuration of the aircraft as well. Had an F-22 tell me once that the Raptor is stable in take off and landing configuration (gear and flaps down) but unstable in flight config.
I have been flying model planes for years.. and while most models aren’t truly dead on scale the F16 is considered one of the best flying models of jets..It flies fine without any complicated gyros on board... the fuselage provides a lot of the lift and stability.
Thanks Mat, I had no idea that it all revolves around the relationship between CG and CL. Makes perfect sense once explained, but in my mind, the whole instability thing was much more complicated than that. I thought it was all structural design features and black magic.
Thanks for the very educational post.
Good to know...so I’m a putz...at least we got to talk about some cool airplanes and models. LOL! Thanks for the post.
You are correct about the F-16's inherent instability and this instability is desirable for an aerobatic airplane like a fighter. From Wiki:
Negative stability and fly-by-wireThe electric jet/lawn dart F-16 was a huge step, an honest technological leap actually, beyond the F-4 or anything the Soviets or anyone else were flying at the time.The F-16 was the first production fighter aircraft intentionally designed to be slightly aerodynamically unstable, also known as "relaxed static stability" (RSS), to improve maneuverability. Most aircraft are designed with positive static stability, which induces aircraft to return to straight and level flight attitude if the pilot releases the controls; this reduces maneuverability as the inherent stability has to be overcome. Aircraft with negative stability are designed to deviate from controlled flight and thus be more maneuverable. At supersonic speeds the F-16 gains stability (eventually positive) due to aerodynamic changes.
To counter the tendency to depart from controlled flightand avoid the need for constant trim inputs by the pilot, the F-16 has a quadruplex (four-channel) fly-by-wire (FBW) flight control system (FLCS).
“So my question is; How is the unstable F-16 model can fly so well without its flight computers?”
“If you put enough power on a door, it will fly”. Something my first flight instructor told me, many years ago.
The relative power curve is probably higher on the model, than on the real thing. Just my guess.
Yes, I can see that. Flap settings could change staability too.
F-16 jocks do low pass stuff over my farm all the time and the horses try to jump the doors n` run out of the stable.
F-16 was an inherently unstable aircraft coz it unstables the horses.
Boats, V-hulls and flying wings are similar.
Blue angels fly 18s
Don’t know if he is using them, but the miniature gyros available for model planes and helis are quite amazing. You can set them up to correct for unwanted pitch, roll, or yaw. They sense deviations in position not initiated by the transmitter (pilot) and automatically move the servos controlling the flight surfaces to try to correct for it. If the movements coincide with what the pilot is doing with the transmitter, they allow movement proportional to the amount of stick input. They are not perfect, but they make flying unstable RC aircraft much easier. Especially helicopters.
I’m cured! I’m cured! Thanks for the information GBA.
Thank you Phlyer. Cool and educational.
LOL! Poor horsies.
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