ThomasP

High Folks,

I have noted at quite a few jet meetings, a model will be on a nice stabilised approach to land, then as soon as it gets in to ground affect, or in gusty conditions the model will balloon up again maybe to 5ft or 6ft, get very slow and in worst case stall and cartwheel.

Would a gyro on the elevator help in this situation? I must confess I have not actually aware of any one using a gyro on the elevator.

Regards,

Alistair.

seanreit

My Feedback: (60)

Was this a delta airplane?

ThomasP

Sean,

No, it is twin boom, Boomerang intro, however seems to affect all models to a degree depending on conditions at the time.

A

ianober

My Feedback: (12)

I dont think a gyro would work cause the problem you are talking about is caused by lift, not AOA. If the gyro could compute "altitude" then maybe. All th gyro would do is help hold the AOA nose high.

ThomasP

Ian,

Thank you for your input,

A.

DaveMatthews

Using gyros on elevator, (and ailerons and rudder) is what is now common place. So go for it. Many competitors at the JWM use all three axis.

ianober

My Feedback: (12)

This may be true, but in Thomas' situationthis wont help. A gyro is great for holding heading or attitude, it will not help to compensate for ballooning, in fact it may hurt. If you were coming in on final holding a high angle of attack and bleeding off airspeed a gyro would help hold that. As you slow down the nose will want to drop but the gyro would want to hold the AOA thus inputing more elevator and slowing the aircraft more and more. I think would result in a rapid stall.

For normal flight I think it would smooth out flight, i.e. holding your altitude level and correcting for rough or bumpy air.

Give it a try Thomas, I am curious to see, just don't wanna try it on my plane

HarryC

My Feedback: (1)

I can't say I have noticed that, except occasionally where people come into land too fast so that as they raise the nose to flare, and they raise it too rapidly without allowing plenty time for the speed to bleed off, so the plane climbs. The model can only climb up 5 or 6 feet if it has enough lift to do so, thus demonstrating that it was going too fast and was not close to its maximum angle of attack as it got into the flare height. A wind gust from in front can lift the model a foot or two, but it would take a very big gust to lift it 6 feet, unless it still had too much speed anyway.
Harry

jescardin

My Feedback: (1)

I have first person experience using normal and "heading lock" gyros on RPV target airplanes during nearly 10 years and I may asure you that a normal gyro controlling longitudinal axis will soft and LIGHTLY self stabilish the plane on that axis but do not expect a total selfstabilize device and be prepared to "fight" against the gyro when pushing into dives and MAINLY when pulling out of them (you will need a lot of control for entering and exiting dives). Reagarding the use of "heading lock" gyros on elevator.....just forget about it!.

Best Regards.

Jesus Cardin

erbroens

I made some experiments on pitch control using a standard gyro many years ago, and one of the best results from this experiment is how the gyro smoothed out the landing final approach on a prop job (a P-51).

On one particular experiment, I mixed the elevator channel with the gyro gain, so the gyro is working at it´s max when the stick is at the center. When control authority is needed, the gain is reduced as you apply elevator, so the gyro wasn´t fighting against your commands.

One problem is that the gyro can start "hunting" if the gain is set too high at higher speeds.. and this can lead to a crash due to aerodynamic stress on the airframe and controls , but you can also turn the gain off with the landing gear switch.

However, until this date I haven´t found a jet that needed a pitch gyro... IMO with a good setup, it is very difficult to make anything unlike a rock steady landing approach, unless of course there is heavy turbulence or strong cross winds.


Enrique

Likai

If you move C.G far backward than normal setting for manuvibility reason( like many real advance modern fighter jets), heading-lock gyro for pitch is the only answer. If not, it is no necessary.

ThomasP

Hi Guys,

Thank you all for the input, I think overall the opinion is to leave well alone, and adapt to the conditions on the day.

Alistair.

ela

Well I have seen this to. But I don't think it can be explained by anything else than lack of experience or nerves.. Keep the gyroes where they belong. In a helicopter.

jseppanen

My Gripen (AW, 1:5 scale, around 44lbs, P200 power) will have three gyros in it. ACT Fuzzy Pro Logic V2 all the way. Why three you may ask - two is not enough and four is too many! Absolutely no idea where the CG will be. Hopefully in front of trailing edge. Must compensate with gain... Any suggestions? You know how the real thing flies without gyros? - well...it doesn't...

joeflyer

My Feedback: (48)

Whatever for? Just put the CG where it belongs and fly it. As Likai mentioned above the reason the real one needs gyros and computer augmentation is because of its rearward CG. The rear CG makes the plane very manueverable but inherently unstable. The computer augmentation compensates for the instability so that its flyable.

With RC models we move the CG forward to make it stable. My Skymaster Gripen is very stable and manueverable enough for me. Get rid of the gyros and use the recommended CG. You can experiment somewhat with the CG location to fit your flying style.

Joe

jseppanen

The point is to experiment with the airframe and capabilities of my flying skills. I'm sure the plane will fly great (every delta wing plane does) without any gyro assistance. What is great? I'd like it to fly even better and scale-like. Have you seen how the real one flies? Especially the high-alfa manouvers? No RC -plane (Gripen) does these like the real thing! My Rookie II is close though...sometimes...

Experimenting with all the 'gizmos' is what's it all about for me... The maiden will not happen before April but I'll post a video no matter what happens...keep your fingers crossed...