Awesome RC Model Plane (Vanity)

YouTube ^ | 08-27-2014 | Self

[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 owner’s 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

[Sergio]

I will be in and out so please excuse any delays in replying to posts. Thanks in advance for everyones expertise and sense of humor.

[ImJustAnotherOkie]

The F117 was unstable and un-flyable without computers but I never heard of that associated with the F16.

[Rennes Templar]

Heck, build it a little bigger and you can hop in and take a spin!

[SJSAMPLE]

I think the “too unstable” stigma was originally given to the F-117 “Wobbly Goblin” stealth “fighter”. I believe pilots have dispelled that rumor.

The F-16 was the first production fly-by-wire aircraft, but that was because the unique control configuration and the desired performance envelope.

[MtnClimber]

It is not just how the model looks. I believe the real F-16 has the center of mass behind the center of drag so it would tend to swap ends if not for the computer controls. The model would only need weight distribution to move the center of mass in front of the center of drag. The tail even increases the drag behind the center of mass if the model starts turning a bit sideways.

[Steely Tom]

I never heard anything about the F-16 being inherently unstable.

F-16 was developed in the early 1970s, with first flight in January 1974 (according to Wikipedia). This was several years before the first active computerized fly-by-wire aircraft were demonstrated; if I recall correctly, the first such aircraft to carry a human pilot was the Grumman X-29.

[DCBryan1]

Everyone knows that if you put a big enough engine on ANYTHING, it will fly. Exhibit A: The F4 Phantom

[driftdiver]

The F117 required computers to fly as it would depart from normal flight if the computers went down. This is called negative stability.

I don’t think the F16 has that problem. It requires computers to fly but will stay in the attitude it was when the computers were lost (neutral stability). Its more complex than that but there are definately model F16s that fly.

Do a search on “airplane stability” and you will find some good sources.

[skinkinthegrass]

absolutely Awesome, w/o icc.
didn't know turbojets engine are that small.

[blueunicorn6]

The F-16 was unstable, but after four years of intense psychotherapy, and lots of mood-altering drugs, it worked through all the issues.

[Sergio]

Thank you for your kind replies and my apologies for having mixed up my aircraft history, F-16 vs. F-111. I could have sworn that it was the F-16, but obviously it was not.

As I get older, I suffer more and more from CRS. (Can’t Remember Stuff)

[Sergio]

That right there’s funny.

[Sergio]

Thanks driftdiver, I will do that.

[SpeakerToAnimals]

It is called relaxed static stability. Move the CG far enough aft and the plane is unstable. But it turns much more responsibly. That is what GD did to me the F-16 so maneurable. The model has the CG further forward and is stable.

[USNA74]

Not certain of the real answer, but the fact that the Blue Angels flight demonstration team flys them for that purpose means they must be pretty darn stable.

[CrazyIvan]

I remember two assessments of the Phantom.

1. With enough thrust a brick will fly.
2. It has the glide rate of a man hole cover, on edge.

[DJ MacWoW]

Did You Know?

The Current FReepathon Pays For The Current Quarter's Expenses?

Now That You Do, Donate And Keep FR Running

[SJSAMPLE]

I the X-29 came significantly later than the F-16.
Mid to late 1980s, IIRC.

[RckyRaCoCo]

You mean the Thunderbirds?

[Mat_Helm]

Because a model does not have the same weight, thrust, CG, aerodynamic forces involved. The model may look like an F-16 in dimensions and wing sweep, but does not have the same wing profile for supersonic flight, slats and flaps, fuel cell transfer system to maintain specific CG during flight, and other factors. Control surface dampening and computers prevent pilot induced oscillation (PIO) and require functioning AOA sensors along with the flight control computers. If you lose all the AOA sensors the plane is equally difficult to control. As the nose departs one direction and the pilot corrects it departs again in another direction and or over corrections by the pilot until he is chasing it to the point of complete departure. F/A-18 Hornets have the same problem if you lose the AOA sensors. The flight computers are continuously making small trim corrections to maintain 1G flight with hands of the stick. Even with pilot inputs to the controls the computers chose the best assortment of control surface deflections to accomplish the directional change input by the pilot as programmed and with design limitations for allowed positive and negative G forces. Flight test pilots take the test aircraft to departure limits in the design phase with unlimited and dangerous control and from subsequent tests software engineers create the code that than limits flight control movement to prevent loss of flight control. That is why flight testing is dangerous business and flown under strictly scripted maneuvers over time and testing departure limits beyond the wind tunnel and computer modeling.