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  1. #51

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    RE: To Gyro or not to Gyro?

    David,

    What issue of RCJI was your gyro article in?

    I am contemplating fitting a gyro on the ailerons of my skymaster F16 (1/8 one first) as it is a twitchy thing in a crosswind and I think could greatly benefit from a gyro on the ailerons and probably rudder as well. Taking off is not a problem but landing in a crosswind is a real challenge.

    (all of the "I am a hero....I don't need one when I fly once a year....you guys need to learn how to fly" crowd can give it a rest or better still, roll up at my flying field with a SCALE jet and show me how it is done in a 20kt crosswind. I will supply drinks, popcorn and dustpan and broom for afterwards )

    A question for those experienced with gyros on ailerons in jets....do you guys only run them in normal mode or have you tried heading hold mode?

    Craig.


  2. #52
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    RE: To Gyro or not to Gyro?

    Craig, it was four or five issues ago. I think I have the text on my laptop here in London if you can,t find the magazine. Clearly there are a lot of misunderstandings about gyro operation and I have tried to clear them up and explain the principles in that article. A gyro is of little help in a X-wind as the aircraft doesn't KNOW its a crosswind, relative to the runway, until it touches down !

    I think in fixed wing models the helicopter term "heading" hold should be renamed "attitude" hold because you can't use helo heading hold as a heading hold function in forward flight in fixed wing without some weird control crossing resulting in perhaps severe control difficulties. Properly used a good piezo gyro can transform a frisky model into something rock solid, going to install one in my F4, Mig 29 and little L39 when I get home. My Bobcats, Hawks and Sabre already have them.

    Regards, David.

  3. #53

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    RE: To Gyro or not to Gyro?

    Hi David,

    Thanks for the info and the offer. I think you have misinterpreted my goals with the gyro in the F16. I am not looking to make the model line up with the runway and get the gyro to hold it there (ie. literally hold that heading), so, while I agree with your comments there, they don't relate to my question. I used the term "heading hold" as that's the traditional term, not my literal intention, and I have been doing alot of heli flying lately (good for teaching use of the left thumb).

    The fact is that the F16 is twitchy and sensitive to crosswind gusts or rapid wind shifts. It is this I am looking to tame. The tall fin seems to make the model particularly susceptible to turbulent air. I have noticed that when turning onto a crosswind finals that I had difficulty maintaining a constant angle of bank, so much so that I had to fly it like a heli and apply a significant amount of rudder and aileron to maintain a constant angle of bank. The rudder on the f16 generates some potent roll coupling (forgive me if I am not using the right terminology) I am not a full size pilot, but I have lost count of how many flights I have had on the 1/8 F16 and I have discovered pretty much every idiosyncrasy it has. I remember one day rolling to upright attitude from knife edge in approx 1.5 seconds only with application of rudder so I can back up my comments about the rudder/fin potency with factual observations. I suspect the fin/rudder is very potent, with this model, at inducing axial roll. I believe that a gyro would definitely help with this.

    I have noted with interest that Philip Avonds recommends the use of a gyro on the ailerons and rudder of his new F15 for similar reasons, and infact, I witnessed video of him making comments to this effect on one of the WJM dvds. I am sure Philip is not trying to use the gyros to maintain a particular heading, rather to tame the tendency of the F15 to wiggle its tail in gusty conditions. Same applies to the F16, hence my question. The point is, in heading hold mode (call it "attitude hold" if you like, that would be less confusing to some), I would expect a gyro on the ailerons to maintain a constant angle of bank and resist the tendency of crosswind gusts to induce unwanted roll, via their influence on the fin. Who gives a rats about maintaining a heading, that's my job.

    So I will ask again, in the context of my comments above, who has used these things in rate mode and who has used them in heading hold mode? I suspect that rate mode would be a safer option.

    Craig.


  4. #54
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    RE: To Gyro or not to Gyro?

    Spot on Craig, you need a gyro to smooth things out and minimise or eliminate the roll coupling. Try it first in rate mode then try attitude hold which can be switched in flight by a channel controlling the gain. You can still control the model easily as stick priority will override the hold function. Have look at the ACT web site, or if you wish I'll send you a copy of the Futaba GYA351 manual when I get back home. If you have model which is twitchy in rough air as you seem to have with the F16 a gyro will work wonders. My guess is you'll love it !

    Regards, David Gladwin.

  5. #55

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    RE: To Gyro or not to Gyro?

    Is there a gyro that works for delta's??
    If you wanted to smooth out roll on a delta that is using delta mixing can the dual channel gyro's do this without affecting the elevator control just by the mounting position of the gyro?
    Just interested.

  6. #56

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    RE: To Gyro or not to Gyro?

    Thanks David, I was thinking along the same lines. I have a separate channel for each aileron. Can you get gyros that are 2 channel but single axis? I am guessing that this would be the way to go if possible.

    Craig.

  7. #57
    David Gladwin's Avatar
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    RE: To Gyro or not to Gyro?

    You can, the Futaba GYA351 and ACT Fuzzy Pro amongst other, do exactly that. I'll show them to you at Temora
    Regards, David.

  8. #58

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    RE: To Gyro or not to Gyro?

    Good news David! Unfortunately I will not be at Temora. Where is the best place to get your hands on the act gyros....direct? Do they come with standard german instructions (ie. none ) ?

    From what I understand it is possible to switch between normal or heading hold using a separate channel in flight, just as you would with a jr770 gyro. Is this correct for both the gyros that you mentioned?

    Thanks,

    Craig.

  9. #59

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    RE: To Gyro or not to Gyro?

    Craig

    The instructions are available in pdf format in German English and French. ACT Fuzzypro

    Klaus the proprietor speaks very good English so language is not a problem. I did a quick check and it looks like most of their instruction manuals are available in 3 languages.

    John

    John Wright

  10. #60

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    RE: To Gyro or not to Gyro?

    I ordered a 2 axis Futaba can't recall # but will let you know when I get it it "claims " full circle knife edge flight with rudder and ailerons landings using elevator and throttle on windy days and ability to stay stable in 15kt gusts I want to put it on my B-25 to see what it does and if it is as good as they say it goes on all my big twins (I got no problem with pride) most full scale stuff I have flown had autopilots and I never heard a pilot complain that he was embarassed to use it. Tony 500575

  11. #61

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    RE: To Gyro or not to Gyro?

    Hi guys, I would just like to back-up Dave Gladwin's comments regards gyro's and jets. In a previous comment on this thread a fellow flyer was hoping to install gyro's on an F16 and then move back the C of G to emmulate the fullsize. The only thing he forgot is the quadriplex flyby-wire system. Various fullsize fighter aircraft use stability systems such as the Tornado SPILS (Spin Prevention Incedence Limiting System) and the Harrier GR7/9 SAHRS system. These modern flyby-wire systems have the aircraft safe operational envelopes as a reference so that the aircraft is never allowed to exceed this SAFE window of operation. This way the aircraft is not allowed to depart from controlled flight. They alter control surfaces a stupid amount of times per second to ensure the aircraft only allows movement to what the pilot requests of it. A gyro on a model jt will not stop you from flying the model poorly !

    During the functional test of the GR7 (SAHRS) the aircraft requires you to select either the single seat or dual seat (T10) varients. This is because they have different aerodynamic properties and so different aerodynamic laws. Therefore some of the parameters will be different. And all the information for these calculations comes via Angle of Attack probes, Pitot and Static probes which are all number crunched usually by an air data computer.

    Gyro's are only useful as DAMPERS to resist an uncommanded movement such as a Yaw Damper of various swept wing civil aircraft and military aircraft such as the Hawk and Jag I believe.

    The best control methods for model jets are the two thumbs operating the sticks.

    This is just my opinion, I have flown all kinds of model jets, heli's and planes and was an aircraft technician on Harriers, Hawks, VC10 and Tornado's for 11 years.

    Happy Flying

  12. #62

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    RE: To Gyro or not to Gyro?

    I run 3 Futaba 401 Gyros in my 3D airplanes (120 size), I can switch from HH-mode, non-HH mode and GYRO OFF in flight, it takes lots of time to set up and understand, (I even crashed one plane), but one set up properly, it is amazing, like ILS on landing, I can land in any conditions, perfect (no tip stalls, dips, etc), in fact I line up on final, then just govern the throttle, let gyro keep plane level. It takes lots of time and practice. You can test on G4, it comes with a yak 54 with gyro

    OK maybe I cheat.....but its better than crashing on landing because of a wind gust
    It doesn\'\'t mean a thing.....if it doesn\'\'t have a wing.

  13. #63

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    RE: To Gyro or not to Gyro?


    ORIGINAL: Likai

    Recently, an experiment what I want to do is moving CG far backward to make the plane aerodynamically unstable( like many modern fly-by-wire jet fighters) and in such case gyro controlled pitch/yaw is the only way to keep the plane flying. I have tried this idea in RealFlight G3 simulator, when elevator and rudder controlled by gyros I can move CG approx 200mm backward in a 3 meter long plane and this plane can make many unbelievable maneuver.
    This SHOULD work, but I think you will reduce your elevator servo life a great deal. I've done this with a 40% Cap 232 I used to fly several years ago, and it was rather surprising how well the gyros settled the airplane down, even with the CG at over 40% of the MAC.
    Doug Cronkhite

  14. #64

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    RE: To Gyro or not to Gyro?

    i have a axe cpv3 i was thinking of getting those head holding gyros why dont these come with the helis,i would pay the extra money.
    anyway i was thinking of getting one is there a cheap one that would work?my problem flying is the tail drifts right or left and i cant focus on my flying. any advice? thank you

  15. #65
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    RE: To Gyro or not to Gyro?

    My 2cents no one at my club use gyros in their jets and that i know most don't use expo either. All thumb control is best control.

    JR

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    RE: To Gyro or not to Gyro?

    HI Jason,

    No-one at our club uses gyros in their jets either......yet. Very soon quite a few will be. The top competitors in the world use them on their models because they are ahead of the game and the rest of us are slowly catching on. I am sure the same discussions ensued many years ago before electronic gyros were used in helis....now you would not think of flying a heli without one, although it is possible. You would not be regarded as a hero for doing so.....more like a fool!

    I don't care whether we are talking about Thomas Gleissner or Joe Bloggs, that little electronic box can react a hell of a lot faster than anyone's thumbs! It is a basic physiological fact that a human's reaction times are in the order of 0.2sec, under the best circumstances, which we are unlikely to experience flying a model jet. Then you have to factor in time taken to deflect the stick to the appropriate position, and adjust that a bit as it is not likely you will get it perfect immediately. You can easily chew up a second or so doing all of this......snails pace by gyro standards.....by which time you twitchy little model has gone knife edge 2 feet off the ground whilst landing.

    Whether a model requires expo or not is not a measure of pilot skill either....some of my models require 30% expo on some flight controls (eg. my F16's) whilst others (like my F18) require none. It just depends on the aerodynamics and inertia of the particular model in question.

    These discussions are a real crack up.....some guys on here are bagging others for using gyros when they don't fly anything more taxing than a boomerang.....but I guess they know how to fly better than the world's best.. Each to their own...

    Craig.


  17. #67
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    RE: To Gyro or not to Gyro?

    Hold on Jason, I'm a member of your club and most of my jets (Sabre, Phantom, F15, 3 Hawks, 2 Bobcats and L39, Mig 29, Starjet and Eurosport ) have gyros, some have 2, and ALL use expo. of a varying amount on aileron and elevator functions ! My Bobcats which you have seen flying at Maitland and other sites for hundreds of flights have had yaw gyros since day one and both now have aileron gyros as do my two big AW Hawks and will my Savex L39 and further upgraded FC Mig 29 ! You might care to try both in your new Velox ! Gyros are probably not needed on calm days but as soon as the air becomes the least turbulent they make a HUGE difference in making the machine smoother and more "solid". !

    As I said earlier it is totally impossible for a human pilot, however skilled, to achieve what a gyro can do and its all beneficial in making the aircraft appear more realistically smooth.

    Regards, David Gladwin.

  18. #68

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    RE: To Gyro or not to Gyro?

    Do you guys get your Gyros from Intairco? I'm looking at testing some on my F-15. Coming from a helicopter background you dont have to convence me on the benefits of Gyros on scale jets.

    I would like to try them on Aileron and rudder. I think I read some use them on the nose wheel steering.

  19. #69
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    RE: To Gyro or not to Gyro?

    With the demise of the Futaba GYA351 dual servo gyro, has anyone used a gyro on just one aileron to control bank angle. I run 2 aileron servos on 2 channels in my Hunter so that I can use crow mixed with the flaps, which precludes installing a single gyro feeding both servos.

    Also, which is the most preferred gyro to use these days.

    Thanks

    Paul

  20. #70
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    RE: To Gyro or not to Gyro?

    Yes David you are correct you are the only one i know that has them from our club. Yes gyros might help but at this stage i do not think i require one. I might not be the best pilot in the world but if i can handle a plane without it i should not need it. The same with expo, i could handle my old ducted fan with no problem where you said straight away you thought it needed expo cause it was a little sensitive for you. I have tried expo and did not like it on the aircraft i tried it on.

    Everyone has there own opinions and who says there is better than another persons.

    JR

  21. #71

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    RE: To Gyro or not to Gyro?

    Hi Paul,

    I believe that the ACT fuzzy pro gyros are the way to go. They have the same capability from what I can gather as the GYA351 with the added benefit of not being affected by aileron trim when switching from normal mode to attitude hold mode (as many gyros are) but David might be able to confirm this as he has used them both. I am just about to trial a 351 for the first time so I am a new comer to gyros in jets (not helis though[8D]) but I can't see myself going back once I get the thing sorted.

    There are a couple of versions of the act gyro....the higher end one has an external sensor from BAe systems.....sounds pretty impressive hey?...David has been using this one I think and he has said it performs very well.

    David, can you chime in hear to confirm?

    Regards,

    Craig.





  22. #72
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    RE: To Gyro or not to Gyro?

    Will gyros on pitch and roll allow me to fly with the CG farther back perhaps? Rate on roll and attitude hold on pitch for example. On the 1/8 F-16 (and probably most modern jets) the CG is so far in front of the landing gear that it's impossible to rotate in a scale manner and difficult to keep the nose up after landing for example. The plane woud be nearly uncontrollable without assistance with the CG that far back.

    The Futaba GYA352 can mix elevons.

  23. #73
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    RE: To Gyro or not to Gyro?

    Due to lack of channels I haven't yet used the attitude hold (it needs the gain to be adjusted in flight to switch between rate and attitude) but now I have 12xs and three more channels I will try it very soon. Use of trim has to be done with care to avoid switching into attitude from rate if the gain is near the center. The manuals explain exactly how to do it. (basically, trim the model in rate mode BEFORE switching to attitude)

    Both the Futaba and ACT gyros work extremely well, extensively used in the JWM. I doubt I will fly another jet without gyros I am so impressed by the result.

    Jason, you have missed the point, its nothing to do with whether you can handle a jet, although it does make them easier (jets are generally easier to fly than propellor models, just faster) its to make the aircraft much smoother and more "solid " in flight. You don't see a fullsize jet bouncing around in rough air in the way that a light aircraft does, gyros smooth things out and a rate gyro on rudder reduces, almost eliminates the yaw/roll couple present on almost all SWEPT wing aircraft. (its a basic and unavoidable fact of aerodynamics and stability) A gyro on ailerons takes care of any residual roll and wing rocking as a result of rough air. many fullsize jets, inc Concorde, have autostabs, too and all swept wing airliners have yaw, rate, gyros on the rudder(s).

    Next time I a m at Maitland we can fly my BobCat and your Velox together, (has it flown yet ?) see which one is smoother !

    As for saying expo is not good and thumb use is best, you just can't say that, its what suits the individual and HIS flying technique AND the control response of the model in question. Personally, with knocking on for 2000 jet flights on a wide range of models, I like it, but your mileage may vary, one size does not suit all !

    Finally I gather ACT gyros will be available from Intairco soon. The Fuzzy Pro is an excellent device, it was recommnded to me by Thommy Gleissner who used it in his Hawk, mine does now ! That said, the new Weatronics 2.4 reciver can be supplied with gyros on all three axes, cant wait ! (No there is NOT one for throttle !)

    Regards, David G.

  24. #74

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    RE: To Gyro or not to Gyro?

    Hi tahustvedt,

    Sounds to me like you have a nose heavy aircraft. My 2 1/8 F16 rotate that smothly you would probably be unable to pick the point at which the model left the ground, but my c of g (skymaster F16's) is at 175mm ("recommended" is around 140!) My model flies beautifully right way up and inverted, rotates and lands well. Where is your c of g and how are you measuring it? Mine has been measured accurate to a mm using a suspension jig. The gyro won't be able to compensate for what may be a fundamental problem with the setup.

    As an aside, a fellow very experienced jet modeller just did some calculations using a aerofoil program on the correct c of g for our F16's.....guess what the magic number was? 176mm! 140mm puts the c of g on the leading edge at the MAC, ludicrous! Gyro won't fix that, especially in rate mode.

    Hope that helps,

    Hi David, thanks for your input.

    Regards,

    Craig.

  25. #75

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    RE: To Gyro or not to Gyro?

    A gyro on rudder really helps control dutch roll on swept wing aircraft like the F-86, F-100, etc.. My BVM F-86 had one and it really flew very nicely.

    Most people IΒ΄ve seen who say they need one on the nosewheel steering simply donΒ΄t have the steering setup properly in the radio. You cannot use the same rate for takeoff that you need for taxi. Furthermore, the real problems I see are the pilots who simply slam the throttle open fully, release the brakes, and pray the aircraft runs straight.

    What I always did with the F-86, was bring the power to about 50%, release brakes, let the airplane start accelerating, and then smoothly bring the power to 100%. I also hold just a little up elevator all through the takeoff roll to help keep the nosewheel a bit light. This is especially important for airplanes like the BVM Bandit, where power application forces more weight onto the nosewheel. This is important enough that BV puts it in the flight instructions in the builderΒ΄s manual even.

    One can hardly call a gyro cheating when many full scale aircraft had yaw dampers on them (I think the F-100 series even has them).
    Doug Cronkhite


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