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Gyro assisted CofG

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Former Member13/01/2019 19:11:27
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MaxG14/01/2019 11:16:08
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Isn't this how they set up the modern agile full size combat aircraft? Rear COG for agility ( thus unstable) and a flight control system to make it flyable.

Maxg

Former Member14/01/2019 11:21:44
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Simon Chaddock14/01/2019 11:44:03
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suoertigerfan

Likely because a military gyro system costs £ tens of thousands rather than £ tens and is fully duplicated or triplicated in case of failure.

And the plane will crash spectacularly if anything goes wrong.

Former Member14/01/2019 11:53:03
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Chris Walby14/01/2019 12:37:09
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Having watched the "Little and Large" aerobatic display team + some very talented RC flyers I have to ask is there anything else left to squeeze out of an airframe that has not been done already?

Pitting a full size aircraft against a large RC aircraft demonstrates the levels of performance of each. I think the RC has it because of the limitations of the on board pilot in the full size.

I vaguely remember someone saying that the current Typhoon can pull in excess of 15G, but is limited due to the on board pilot.

PS we rely on TX to RX with a single point of failure so relying on the giro working at all times is nothing new, but does it add to the experience?

Former Member14/01/2019 12:52:05
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Frank Skilbeck14/01/2019 13:55:45
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4310 forum posts
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It's an interesting one, in theory yes, but you usually have to do a few flights to tune the gyro to suit the plane, with ability to switch the gyro off being the get out of jail card. Will be interesting to use one in an unflown plane, but something like the Wingstabi with the Easy firmware where it automatically adjusts the gains might just work. Or a flight controller/gyro which has auto level capability (similar to the helicopter flybarless controllers).

I think I would test it out on a hack model, i.e. move the c of g back and then fit the gyro, before putting it in a nice scale model that hasn't flown before.

Chili Pants14/01/2019 15:38:41
16 forum posts
13 photos

I recently returned to the hobby after some 40+ yrs, I am building a old classic aerobatic and our runway layout will necessitate cross wind landings most of the time. So last year I got a low cost Gyro mainly to test out its ability for stabilizing these types of landing, as a test bed I used a HK Voltigeur, a 3d type model, (CG towards the rear but not excessive) now I can land this cross wind without much of an issue (10/15mph + cw) but with the gyro on, I could just as easily be doing a normal into wind landing.

When setting up the model and Gyro the instructions tell you to set the model up in the correct flight attitude and when switched on the Gyro will maintain this flight profile while still allowing control inputs, all in all a much smother flight, (on rails) so I would think it should be able to deal with a bad CG, although I have not tested this because my main use was to test its suitability in dealing with crosswinds and for 99% of a flight the Gyro will be switched off.

There are other functions/modes available on the Gyro, the club instructors face was a picture when I (the Gyro) started prop hanging and pirouetting down the runway surprise

There are quite a few Gyros available to suit most pockets and well worth trying one out, as already mentioned on a hack model first and they can be quite fiddly to set up at first.

Don Fry14/01/2019 16:16:10
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3300 forum posts
39 photos

Don't know, but a few thoughts.

Some of us use a forward CG, and a coarse elevator. Some use a CG further back, with small throws. This bloke started with a 25% CG, which I think is well forward, but that's his choice, his plane. He then moves it back, until he has a "wild ride", he describes. Now, I would reckon, any aircraft which has had its CG shifted from 25% to 37% without altering the control throws is going to bite. I wonder if any attempt was made to tame it without giro, and he never got to the stage where it's in unstable territory.

Still a whole ball park away from using it on a serious already weighty, rearward CG maiden warbird

I personally would have a go. No use if you won't fly it. But I would be kicking myself that I failed to get that back end less on the porky side, and/or not got the radio bits, batteries etc well forward.

But I might also be tempted to get it up with the lead up front, fly it carefully, and shift the lead out, once I've got it trimmed with the giro also trimmed out.

Hope he succeeds. Game of blood this hobby.

Former Member14/01/2019 16:38:15
724 forum posts

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Denis Watkins14/01/2019 17:01:45
3494 forum posts
165 photos

The stabiliser will do all that it can to keep the model level, like you say ST when the sticks are neutral

Which is OK But

A stabiliser will use all the servos, all the time to do this with incorrect C of G

Most sports models with 3 servos needs checking for Rx power frequently

A 5 servo Warbird, would need a good battery check regime, as All 5 servos will work All the time in the breeze anyway.

The Stabiliser would compensate for incorrect C of G, but bear in mind

It maybe a good portion of your elevator is already in use by the gyro

Definitely a big surprise with the gyro off

This all needs testing out

Chili Pants14/01/2019 17:32:41
16 forum posts
13 photos
Posted by Denis Watkins on 14/01/2019 17:01:45:

The stabiliser will do all that it can to keep the model level, like you say ST when the sticks are neutral

Which is OK But

A stabiliser will use all the servos, all the time to do this with incorrect C of G

Most sports models with 3 servos needs checking for Rx power frequently

A 5 servo Warbird, would need a good battery check regime, as All 5 servos will work All the time in the breeze anyway.

The Stabiliser would compensate for incorrect C of G, but bear in mind

It maybe a good portion of your elevator is already in use by the gyro

Definitely a big surprise with the gyro off

This all needs testing out

All good points here, I should mention that while attempting some Gyro assisted 3d moves for a few minutes, control seemed odd, I switched the gyro off and landed ok, for the next flight/crash the Gyro taxed the ESc`s Sbec so much it burned out and I had no control, simply drawing more power than the Sbec could supply and down she went. It was a cheap HK ESC so I replaced it with a better one with a 5Amp Sbec and no issues since, so its worth bearing in mind the extra power draw that a Gyro can induce with constant multiple servo activation.

With noticing the Gyro, the only time that I have noticed it is when I switch it off, when flying in cross winds you get wing rock and have to compensate, ie see a wing drop, put opposite control in, when the Gyro is on it corrects the wing rocking before I can even see it start and if I need to turn or change altitude, even in gusty conditions it does so without a glitch.

I do not do a lot of flying with the Gyro on but when I have done a few circuits, I have noticed that the controls seem not wooly as such but almost as if the rates had been turned down and stronger inputs are needed and the model fly`s in a much more sedate manner, this would seem ideal for scale type flying.

hope this helps.

Frank Skilbeck14/01/2019 18:42:51
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4310 forum posts
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Posted by supertigrefan on 14/01/2019 16:38:15:

Interesting stuff.

I'm under the impression that a flight stabiliser only 'intrudes' when there are no signal inputs so what effect would it have on an unstable aircraft once it receives a command?

Would it be imperceptible or would there be a momentary twitch between the stabiliser relinquishing control to the receiver?

Not quite true, in stablised mode the gyros are always working, what happens is that the stick position is then taken as a command to rotate the model around an axis and the unit then send instructions to the relevant servos. If you set the gain too low it can make the model responses very slow, too high and you can introduce instability, every model needs different gyro settings.

One thing the writer could do is run his models parameters through a program like https://www.ecalc.ch/cgcalc.php and then determine the maximum rearward c of g, I think if you actually move the c of g too far rearward, so you need a lifting tail section, could be very interested.

Nigel R15/01/2019 11:31:12
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2483 forum posts
406 photos

"£ tens of thousands "

I can say with a fair degree of certainty that military control systems cost just a tiny little bit more than tens of thousands of pounds. Just ask SAAB.

"the club instructors face was a picture when I (the Gyro) started prop hanging and pirouetting down the runway"

The local font of knowledge was recently overheard commenting to another flyer that all 3d models used gyros, no pilot skill is necessary, so he wouldn't bother getting a 3d model, after all why bother with them when it is just a gyro flying it for you.

Next week, same font, is flying a HK Convergence.

Chris Walby15/01/2019 12:52:02
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870 forum posts
211 photos

Is Mr Top Letter missing something....Picking up on a comment earlier, does it not also depend on the model?

My carbon yak has stabilisation (turned off until its windy) and has large control surfaces plus digital servos of which you can hear them continuously operating in windy conditions.

Will the Warbird have sufficient control surface area especially at low air speeds to maintain control, could it make landing much worse by waggling the ailerons when you normally just use the rudder and elevator on finals? Hence inducing tip stall?

Help or hindrance only time and money will tell.

The Wright Stuff15/01/2019 12:59:01
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1383 forum posts
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Posted by Chris Walby on 15/01/2019 12:52:02:

Will the Warbird have sufficient control surface area especially at low air speeds to maintain control, could it make landing much worse by waggling the ailerons when you normally just use the rudder and elevator on finals? Hence inducing tip stall?

Point taken, but I assume that by intervening much sooner than a human pilot would be able to react, the required deflection to correct would be much smaller...

Former Member15/01/2019 13:06:19
724 forum posts

[This posting has been removed]

Denis Watkins15/01/2019 13:34:04
3494 forum posts
165 photos
Posted by Chris Walby on 15/01/2019 12:52:02:

Is Mr Top Letter missing something....Picking up on a comment earlier, does it not also depend on the model?

My carbon yak has stabilisation (turned off until its windy) and has large control surfaces plus digital servos of which you can hear them continuously operating in windy conditions.

Will the Warbird have sufficient control surface area especially at low air speeds to maintain control, could it make landing much worse by waggling the ailerons when you normally just use the rudder and elevator on finals? Hence inducing tip stall?

Help or hindrance only time and money will tell.

Truthfully Chris

At £20 for an add on kit, your warbird will never tip stall again

As always, its horses for courses

A stabiliser will not fly your plane, you know that, but you get to fly days extra where otherwise you would be at home

Former Member15/01/2019 22:55:38

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