adjusting control throws

[Phil 9]

I have been experimenting with the control throws on my Great Planes Revolver 70 to see if I can get some more movement from the control surfaces.

Pushing thing to the max I found on both the elevator and ailerons I can get more travel in one direction than the other ie more up elevator than down and the same on the ailerons.

Is it a bad idea to leave them in the max but unbalanced throws. What effect might it have if I do

[Biggles' Elder Brother - Moderator]

Well, it will make the control more sensitive in one direction than the other! To what extent and how noticeable the effect is will depend on just how inbalanced they are.

Can I ask why you feel the need for so much more throw? I've flown the Revolver and its a nice fairly aerobatic sports model.OK, its no 3D-er but then its not meant to be. If you want something that will really flick around, you really need a different model - the poor old Revolver isn't meant to do that!

Also, on a model that isn't designed for it you might find it starts doing some rather undesirable things at very large throws. For example, very large down aileron throws create a lot of asymmetric drag. This can lead to a heavy adverse yaw, that pulls the wing backwards and then stalls it!

BEB

[john stones 1 - Moderator]

If it's too nose heavy it would liven up a bit if you moved c.g back phil, careful though

John

[Martin Harris - Moderator]

I'd be looking at the geometry of the linkages - are the output arms, horns and clevises at 90 degrees at neutral? Moving the output arm a spline or two (and adjusting the linkage to suit) may even things up if not - even compensating for such problems as hinge-line/horn misalignment.

An unfortunate by-product of modern radios is that many people are a bit lazy, relying on ATVs rather than setting all components at optimum to give the desired range of movement.

[cymaz]

Phil, is the you tube video what you mean. Or do I have the wrong end of the stick??

 

http://www.youtube.com/watch?v=v09QzKBipN8&feature=youtube_gdata_player

Though, if you have unequal throws then the servo arm may not be at 90' to the body as previously mentioned. The arms on futaba have numbers on them which describes how many degrees they are off true. Also make sure that the sub trim is at zero before set up.

Edited By cymaz on 03/05/2015 06:48:54

[Bill_B]

I'm also not sure why you'd really want to max out the control throws on the Revolver as it has quite a slippery airframe and is fast, in any of three sizes it comes in. I have the smallest .46 size version and if I'm honest it's more like a pylon racer than a full on aerobat, with large smooth manoeuvres order of the day. IMHO I wouldn't go more than the manual's recommended high rates. Also, as BEB has already alluded to, differential movement on the ailerons of this model will only serve to give you untidy rolling manoeuvres with unwanted adverse yaw. Not recommended.

[Phil 9]

Thanks for the comments all relevant points.

I should be careful about pushing a models limit beyond what it was originally designed for.

I was trying to get the roll rate a little faster at slower speeds and I wanted a little more elevator to make flat spins a little flatter. adjusting the CofG may help with this

I did read up on adverse yaw and using aileron differential to counter act the effects. But I not to worried about the aileron setup as it is not too extreme but I will watch out for any yaw effects

the geometry of the links I did adjust to get as much throw as possible. the elevator wire rod links are very long on this model and are not supported on most of the length. on extreme servo movements they are bending creating slop. I will back them off to avoid this and then set them with equal throw each way.

I want to get the most out of this model but I don't want to ruin it

[Bill_B]

Phil, I must admit that the rod and linkage geometry on my Revolver is pretty much pants, in fact 'Great Planes' is a bit of a misnomer for the company as IMHO Seagull Models kits are much more nicely constructed, covered and thought out, but that's just in my experience. Anyway, ailerons aside, the rudder and elevator(s) horn placement is not well thought out because the clevises can only pick up on the two inner holes on the horns due to bad placement of the pushrods exits, and this isn't ideal. I'd much prefer to have the choice of the outer two holes for more precise control, but then I suppose with wire pushrods traversing through large plastic tubes is never going to give accurate control. In reality this poor set up doesn't show itself too much when flying smooth wide open manoeuvres, but I'll always be cautious of the possibility of flutter at high speed.

Back to one of your points Phil, a more rearward CG is an almost guaranteed way of improving spinning ability and I generally set my sport models so that very little, or no elevator input is required when inverted, but again that's my preference. Some models aren't apt to spinning flatly no matter where the CG is. As an example I have a Viperjet that resolutely refuses to enter a flat spin, even with a rearward CG and maximum rudder & elevator movement, so increasing the throws is not guaranteed to give you what your after. My best model for flat spinning is the Eflite Carbon Z Yak, but that shouldn't be surprising!

Bill_B

P.S. I've not tried the Revolver in a flat spin........yet.

[Phil 9]

Bill_B I do agree with you about the links. When I built mine a added a closed loop for the rudder but the elevator set up is not great. As you say the holes do not line up well and I ended up putting a kink in the rods to make mine fit. it is just about adequate but it could have been done much better. Having said that I do like the revolver

[ASH.]

I would not tolerate any kind of slop in my models' linkages/surfaces and will do whatever needed to eliminate. Consider replacing metal rod with 2mm carbon epoxying threaded extenders at both ends. Have a clevis at the servo end and ball joint at the other. Also you could reposition servo slightly/ move control horn to achieve a straight run, even have a different exit hole. A quick fix is to glue a ply brace vertically where the rods exit fuse to support/restrict lateral movement.

I too use to believe in having maximum throws on control surfaces (which was never needed) using longer servo horns etc.. but now know better. Less is more.. I prefer more torque and resolution.

[Phil 9]

A guy on flying giants mounted the servos in the tail.

here

if I got another one new I would do this but Its not worth it to me now to do that much work to modify my old one.