Servos & power supply for 50cc/88

[Steve Fish]

Sorry for the long title...

 

New to the larger plane, and dead keen. However the manual for my Edge 540T, 88", says "no less than 9Kg/cm torque servos please", 2 for aileron, 2 for elevator and one for rudder. (standard for throttle...) So what servos:

 

1. - Digital or not?

2. - metal gear or not?

3. - Best vale for money servo in this class (including hobbyking-derived brands) is....?

 

Then - battery set up.

 

Is 2x high capacity NiMH packs with thier own switch harness enough or do I go 2x lipo 2s, each with their own voltage regulator?

 

 

What do you use?

 

What about the Fromeco Wolverine switch???

 

What set up should I go for?!

 

 

 

[r6dan]

Whats the budget? or does it not matter?

[Stefan Hafner]

I used a bunch of JR 8411's for my 2m Raven, bit expensive but i think at that sort of size reliablity comes first, they are metal geared and digital.

 

I have the same number of servos as you will and I used a single 3700mah pack with a heavy duty switch and not had any problems with it, just fitted a battery checker and give the pack a quick top up if i feel it needs it between flights.

 

I think if i was going above 2.5m I would use something like a powerbox with Lipos for power but at 88" i don't think its really necesary

 

Just my 2 cents

[Ultymate]

Metal geared for sure don't go near Karbonite gears they don't like vibration. The choice between digi or analogue is mainly down to your budget . The choice around 8-10 K is about right for a 50cc model, no need for a powerbox but maybe some sort of dual battery set up and a failsafe (ie fail "on") switch.

[Steve Fish]

Budget: Fairly tight: I'm in New Zealand-

(felt the 'quake - some 200km away. thoughts to the affected... esp as this is quite trivial in relation to that...)

- but can get mail order of course and always want value for the buck. Any thoughts on the Bluebird range of servos?

[Stefan Hafner]

I've never heard of Bluebird servos before so can't really comment on them, Hitec are generally pretty good both on the cost and quality front, the HS 985-MG on a lagre 4.8v pack or HS 965 MG on a 6v pack would be perfectly up to the job. If you wanted digital something like the HS 5685 would be good, but it does want a higher voltage supply so a 6v pack or 2s LiPo. For digital on 4.8v something like the HS 5645 would be just the ticket, and cheaper too.

But then there are probably another hundred other servos out there that you could use too

Edited By Stefan Hafner on 28/02/2011 20:31:08

[Brian Cooper]

I have been playing with 50cc (3D) aeroplanes for a while, and have been using Hitec HS5985MG digital servos, and Futaba S9451 digital servos. They are fast, accurate and powerful, and get the job done without any dramas.

Batteries: I use twin, high capacity, A123 LIFE battery packs (no need for a voltage regulator) for the radio, running through a AR9100 PowerSafe Spektrum Rx (with three satellites).

The ignition runs on a separate NiMh pack.

This Rx can handle a very high Amp demand from the servos and eliminates the need for a power box on 50cc machines.

 

The sad fact of life is that when models get bigger, so does the cost of getting them ready for flight --- and it doesn't pay to try to do it on the cheap. The old addage of "buy cheap, buy twice" is very real when playing with larger models.

 

Good luck.

 

B.C.