Primodus

My Feedback: (56)

I have recently rehinged the ailerons on my old Sig Hog Bipe. I flew it today for the first time and the roll rate is pretty slow, even on high rates. Mine is set up using a single servo to drive all 4 ailerons.

Here's the question...

Should the upper ailerons be offset from the lower ones, be it raised or lowered? Or...

Should all the ailerons be even with the wings to start with?

Thanks[8D]

Tall Paul

You might seperate the wing surfaces servo.. add one to the top wing, or better, two.
Or one to drive the left wings, and one for the right wings. This works fine on my SIG Ultimate Biplane.
Four surfaces is a large load on a single servo, with the slop of all the connecting linkages summing up to less effectiveness.

Hircflyer

On my Hog I use two servos..........to answer your questions the ailerons should be even with the wings to start with.......this may change later after trim flight(s). I did not offset my upper wing ailerons I know no reason to do so.

What you didn't mention is what was your roll rate before you rehinged? Was it satisfactory? if it was and the only thing you changed to cause the decrease is the new hinges. Same type? Maybe the new hinges were not installed square, that is one or more of them maybe set in the wing or aileron cocked that would cause to bind and slow down the roll rate. Are using the same servo? if so maybe its getting tired. Did you change the hole location on the servo arm where the pushrod is attached that could change the amount of deflection of the ailerons.

Hopefully gave you some ideas where to look.........good luck

Gringo Flyer

My Feedback: (18)

One servo for 4 alerons is a lot especially if it is a standard servo. If your roll rate chaned with the change of hinges you could have a potential problem in the making. I would disconnect the control rod from every aleron and individually check to see if it is moving freely. If one is binding because against the trailing edge it would account for the lack of roll rate. Also, you could test the alerons while it is on the ground (with your TX). Do you hear the servo straining at the max throws? That is, is the servo able to go to max throws or is it binding against something? If so that could account for a lack of difference between max and min rates.

Jim Messer

My Feedback: (2)

Back in 1975 I designed the 1/4 scale Bristol Scout powered with two Webra 60's geared together swinging an 18 x 6 homemade prop. The airplane weighed 17 lbs. and had a wingspan of 78 inches. There are four ailerons, and one standard servo in the bottom wing. We built a squadron of these Bristols, six in all. In 1977 they were all converted to the Quadra 35 engine.

What did we learn? First of all, the standard servo was quite sufficient to power these big models. But - there was severe aileron flutter on all six models, and we were surprised to say the least.

The servo in the bottom wing was attached to the normal music wire/bellcrank system used in those days. A pushrod connected between the top and bottom ailerons actuated the ailerons in the top wing. My co-designer and I are both engineers, and this was a problem we hadn't seen before. So, we mulled it over and quickly decided that the whole system must be in a "loop".
To accomplish this, we added a bellcrank system to the top wing, so that all four ailerons were now tied together.

It worked. No more aileron flutter. Fve of the original models were flown in formation three years ago on the 25ft. anniversary of their first flights. All six models still use only one aileron for the four servos. These models are far bigger than yours, and the power is at least double of yours. So, I say to you - in my opinion your one servo is big enough - just make sure that the ailerons are not sloppy - and if they are (even a little bit) - then consider adding the loop in the top wing like we had to do. This removes the slop and all four ailerons have to move their full amount if the servo says so.

Today, most modelers would use two servos - one in each wing. But - that doesn't necessarily make the system better, but it does make it a lot easier.

Propwash in Pa

If you have not already done, I would recommend that all control surface gaps be sealed. Even if this does not result in a more rapid roll rate, it will reduce or eliminate flutter and vibration. It is a good pratice for all models.

Rodney

I agree that sealing the aileron gap will greatly improve response. However, it has little or no effect on either flutter or vibration.