RVOSD in a Skywalker 1900 anyone?

[g4wft]

Hi,

I've just finished building a Skywalker 1900.  I'm getting the plane trimmed out at the moment without the RVOSD and FPV gear (but with suitable dummy weight added to simulate the extra items).  It flies OK, but I find the ailerons fairly ineffective.  Mixing in some rudder with ailerons helps a lot.  I have the CoG right on the servo wires at the moment.

When I install the RVOSD though and it takes control there clearly won't be any mixing going on, as that's a function of the RC Tx.  The same goes for any autopilot I guess.  So, how have you found the Skywalker under A/P control - any problems with aileron authority?  Do I need to look at getting aileron differential?  I'm using a single channel for ailerons, so it's going to have to be mechanical differential if I go that route.  Or do I need to be moving the CoG a little further back?

Interested to hear your opinions.

Cheers,

Tim.

[BigT]

My 1900 is the same, handles like a canal barge in a crosswind. In my experience differential won't help. It's down to the dihedral and aileron size and the under camber on the wing. As I have always flown large scale warbirds and autogyro I always use rudder, not relying on any mixing to do so. With my MFD AP there is an option to have the ap mix in rudder in auto flight modes but I have not found that necessary. I do find the 1900 very hard to do a steep climb on full power. It just wants to fall off to either side. Again it's the wing.

In auto flight I have tuned  the turns to be  very gentle and the stabilisation high to cope with the small aileron.

My solution would be to increase the dihedral or increase the size of the aileron or open up the flaps cut out and put in secondary ailerons ( 2 more servos). I notice that BEVRC do a replacement wing with a different section and bigger ailerons.


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[dogzilla]

Never had a problems with aileron control with my Skywalker 1900. More than enough for typical flying, I never felt like I needed more. Full lock it's more than agile enough. To get nice turns you need to use rudder.

I use single channel with a Y-Lead through my RVOSD. Works just fine, no need to mess around with aileron differential.

If you are finding your ailerons ineffective have you tried increasing the throws?

[g4wft]

Thanks very much for the replies chaps.  The ailerons are setup with 120% travel on the servos at present, but I could move the linkage to a closer hole on the aileron horn.

What do you reckon on the CoG being on the servo wires?  Could it go a bit further back do you reckon?

Thanks,

Tim.

[dogzilla]

Yeah I've moved mine down to get a decent amount of travel on the aileron.

Never really experimented with CG on my SW. It's always forward of the servo wires, even massively loaded up I just fly nose heavy, it has more than enough elevator to keep that in check and I never noticed it flying worse because of it.

[g4wft]

Fair comment - thanks Dogz.  I too prefer to fly a bit nose-heavy if anything, simply because I've had bitter experience of a CoG that's too far back - it ain't pleasant!

I'll shift the pushrod a bit inwards on the control horn and as soon as I can give it another try.

Thanks,

Tim.