Biplane Ailerons Question

[dave parnham]

Should a Biplane with Ailerons on Both Wings have equal movement up and down?

ie top left and bottom left Both say 20mm and obviously matching on otherside.

Or Can the Top ailerons be 20mm and the bottoms be 10/14mm ?

or even more on the bottom wing than the Top?

 

Electric Hanger9 Beast 60E

 

Many thanks

[Martin Harris - Moderator]

I’m not sure there’s a one answer fits all to this question. It will depend on many factors specific to the model so the best thing is to test fly and adjust differential to suit your taste. The Tiger Moth, for example - although without top wing ailerons - has almost no downgoing aileron but still needs rudder to coordinate turns. 
 

Perhaps others may have flown the same model and can offer pertinent advice?

[Geoff S]

Of all the biplanes I have and have had, those with ailerons on both wings moved them the same top and bottom.  Both my 58" ws DBS&S Moths (Cirrus- as in my logo - and Tiger) have double the movement up compared with down and both can be flown without using the rudder, but I usually do use it. 

 

I think I'd go for both the same for a start, but with differential.  Why would you want them to be different?  Just curious, not critical.

[john stones 1 - Moderator]

I would have same amount top/bottom, on a beast I wouldn't worry overmuch about differential.

[dave parnham]

Thanks i understand differential ,but should clear up that the plane has four seperate servos for each aileron, and the control rods are the same length as per the manual, and all on the same control horns with matching holes etc. yet the bottom servos have less movement than the tops.

I will measure the angles of movement and report back.

 

cheers dp

[Martin Harris - Moderator]

I’m guessing you mean it has one servo for each aileron Dave - 4 servos per aileron would really make it a beast!

 

If everything is identical mechanically then perhaps there’s something in the transmitter mixing that’s limiting movement?  Easy to check by swapping one or both side’s servo connections i.e. top to bottom and seeing if the reduced movement is swapped. 

[GrumpyGnome]

Or different makes of servo.... more info needed....

[PeterF]

Are the ailerons the same thickness, are the control horns on the ailerons set the same distance back from the hinge line. Otherwise as per Martin, it depends how you have generated 4 servo outputs from the Tx / Rx and if all channels have the dame end points / mix.

[Dickw]

15 hours ago, dave parnham said:

Should a Biplane with Ailerons on Both Wings have equal movement up and down?

i...................................................

For many years I flew a Sebart Pitts Python 50E which is very similar in size and setup to your Beast. During the time I flew it I experimented with all sorts of aileron setups and mixing:-
a) all 4 could be moved down like flaps
b) all 4 could be moved - top wing ailerons up, bottom wing ailerons down, (a bit like crow braking on a glider)
c) all 4 could be moved - top wing ailerons down, bottom wing ailerons up (reverse of b))
d) coupled elevator and flaps
e) with and without differential

 

Apart from having a bit of fun experimenting none of the above offered anything worthwhile so I have to say that I flew it 99.9% of the time in a plain setup of "no differential and all 4 ailerons moving just as ailerons with the same throws". I am sure your Beast should be the same.

 

I was rather sad when, after 8 years of regular use, I lost the Pitts to a spar breakage in flight.

 

Dick

[dave parnham]

All four servos are indentical make and theres nothing wrong with Hitecs i think im using,would need to strip the wing to double check or find the manual.

Its a kit so the horns are exactly where they should be close to hinge line all at the same distance.

Ailerons all same thickness. Tx shows all throws on the trims are zero.

As mentioned there maybe some subtrim adjustments in there to align the ailerons at neutral but not a lot.

 

i will get it sorted  thanks gents

[John Lee]

Have you got a servo tester? If so then it will be easy to check for centralisation & throws by plugging each in turn, or together if the tester has multiple outlets (or use Y leads).

[Martin McIntosh]

Rather than using the Tx differential function I start by setting all four servo arms forward to give mechanical diff. as you should do. Each can then be tweaked as needed,

2:1 diff. is a good starting point.