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Questions following RV-6 flight.

All of the modern fighters appear to be built this way, difficult or impossible to control for a human being, the Gripen, F22 and Eurofighter are examples. I’m guessing the F16 was not as “unstable” as the modern stuff.

Unlike the RV the problem wasn’t a problem with sensitivity of control surface versus speed, cg or deflection. The problem was that the prototype in its original version did not have any stick deflection so control surface deflection was driven by the force applied to the stick as opposed to angular deflection.

That sounds a bit like my issue with the RV. At speed there is no requirement for stick deflection to move the elevator enough to cause abrupt pitch changes – very very very disconcerting.

I found this paper online that discusses design of controls and mentions how pilots use stick deflection as one cue to flying the aircraft. It’s from 1948, but hey, what’s new?

Stick and Rudder Controls

Last Edited by Krister_L at 10 May 12:57
ESSB, Stockholm Bromma

Other than allowing for neutral or negative pitch stability, FBW allows independent movement of each control surface. You can’t do that with direct hydromechanical actuation without complicated and heavy mixing units. Or having eight sticks and an octopus-pilot :-)

The local RV community seems to agree that the RVs are “pitch sensitive” and the solution is just to fly more…

Out of interest I asked four or five RV pilots what they thought of your reaction yesterday, as I bumbled into them around the airport. They all said ’he’s just not used to that kind of (light controlled) plane, he needs to fly it a bit more’. That included the RV owning professional test pilot and the unlimited aerobatic competitor who does that flying in a single seat CAP, and has flown every type of plane you could name. So I’m guessing you’ll find it to be true.

Which isn’t to say that more stick deflection in pitch is a bad thing.

Last Edited by Silvaire at 10 May 15:38

Except what these people say doesn’t square with the fact that a properly designed aircraft should if anything have higher control forces at speed, as opposed to evolving from sloppy to very light… When Bob Hall test flew the Bearcat his solution was “increase the stab span” not “duh, you should just fly it more often”.

Thanks for asking around Silvaire!

They are correct, I’m not used to it and I’m sure I will get used to it after flying it for a while.
I just can’t imagine why it should have to be so sensitive…
I read somewhere that some builders shorten the sticks probably in an effort to reduce the effect, presumably introducing other undesirable characteristics.

Shorrick, that’s what I am thinking over in my corner…

Last Edited by Krister_L at 10 May 17:14
ESSB, Stockholm Bromma

Stick forces are an important safety factor. One of the main reasons for crashes of homebuilt/experimental aircraft is loss of control, and very light control forces – especially in pitch – make airplanes mor dangerous. The VAN’s series is considered high quality aircraft, and I have only flown an RV-8 once, 20 years ago, 20 minutes, so i am not really qualified., I do not remember very light pitch forces though and re-reading the article I wrote then, it seems I have not noticed back then either.

What does the “trim tab” on a PA-28 do? It’s called an “anti servo tab” because it makes the controls a bit heavier. And they did that clearly for safety reasons.

An extreme aerobatic airplane is a completely different story and what’s right for those – is not always good for airplanes flown by amateurs with little experience.

PS: I was going to joke “shorten the stick” … before I read the above! Might make a difference!

Last Edited by Flyer59 at 10 May 17:18

PS: I was going to joke “shorten the stick” … before I read the above! Might make a difference!

That’s too funny. I made that comment as we were flying along yesterday! I then read about it online. But, between the aft CG, my inexperience with the type and the fact that it felt good at 120 kts or less I think leave the sticks alone and start with balancing the thing.
Also, it appears the RV-7 and -8 are a little different in feel (better?) so maybe Vans has acknowledged the fact.

Going back in my thread a bit . I have flown the Giles 202 a few times and perhaps you don’t know the type but that thing is an unlimited aeros machine. Wasn’t even close to this RV in feel though.

I probably wouldn’t have made a comment about the aircraft if it wasn’t for the fact that I’ve dreamed about having one since before I learned to fly (23 yrs ago). And now that I have I’m slightly shocked that I didn’t quite like it so much.. :(
I’ll have to buy a Cub instead.

ESSB, Stockholm Bromma

Or a C-206! You’ll not worry about the control forces :-)

Haha, yes indeed!
I guess I have too much time in Cessnas; 150 through 525 – all rather heavy by comparison… :)

ESSB, Stockholm Bromma

Hey, Krister, you have a great website! A little content would be nice though :-))

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