flutter

[jjjvr]

Hi, i am currently building a 1/3 cap 580 and I am a bit concerned about the servos I am using on the elevators. (Actually I am also using them on ailerons) Anyway, they are Hitec's 5645Mg and there are first of all quite a bit of play in the gear train (say 0.5mm on servo arem, but this results in 5mm free movement of trailing edge of elevator!) Furthermore I am not entirely impressed with the holding power of these digitals, I can easily force the elevator a further 5mm with little effort. Bottomline is, how critical is it that one has zero play on the elevators and could this lead to flutter and loss of control. What other servo should I use?

Thanks for any help!

[Boulder]

You may be able to lessen that movement by shrinking the deadband with a Hitec programmer.

The 5645's are said to be a little more prone to centering problems than the 5945's.

[SleepyC]

5645's are good servos, but with that size plane i'd go with 5945's (or what ever the new replacement is ..5845? or something)

But if you have the programmer the 5645's can be adjusted and are very nice servos!

My 2 cents!

[airborneSGT]

Sleepy the 5945 replacements are the 5985:

http://www.hitecrcd.com/Servos/hs5985.htm

I have used the 5925's on ailerons just fine for a plane that size also. The only difference is the gear train. The 5985's will phase out the 5945 so if you want that servo I would snap some up fast. Fear not as the 5985 has better torque, case, bushings to support the gears and is the same price.

[Stainless Skills]

its supposed to be faster too.

I used to have a set of 5645's on a gasser plane and after about 10 flights I switched them out for 5945's. The difference was night and day, the plane flew great with the 5645's but it was just soo crisp and quick with the 5945's.

I did not have a programmer at that time though.

For the money I would really never buy a 5645 ever again because the 5945's I think are soo much better but it really depends on how much better + per $40 a servo is.

[airborneSGT]

Im rolling with the 5955's instead of 8611A's for the gear train difference. Makes more sense to not have to swap out servos.

I really like the 5945's and I have used them in most of my big planes. The 5925 is one amazingly fast servo that I like to use for throttle.

It all depends on your plane size because I have used the 5645's on 28% elevators no problem even with 1.5" arms. I actually tried to crash that plane without success but then again most of my flying is 3D. I know for precision the 5945 is the way to go.

I run 4 5945's in 33% planes alright. I really didnt feel much difference between them or the 5925's on the same size plane.

I am trying out the single servo aileron setup on my Comp ARF however. If your plane can handle it why not go with like one 5955 per aileron instead? Make things easy and save weight. With that much torque the only issue is your aileron itself flexing.