HS-85MG on a 2m flaperon?

[chlee]

Hello all,
I'm thinking of building a 2-meter sailplane with flaperons (Aegea with Barnes-style construction) and am wondering if the HS-85MG would be sufficient for this purpose. The HS-125 is of similar torque, and the stronger 225 is much too thick...

The reason I'm asking is that I read this post by Dr. Drela:
http://www.rcgroups.com/forums/showpost.php?p=2517672&postcount=2
and got a surprising calculated result that I need to check against actual experience.

I calculated that I need around 110 in-oz for each of two flaperon servos for a 150 lb winch load with flaps deflected. This seems to be a bit much. It's possibly too high because I'm assuming K=0.25 for launch, corresponding to 15 degrees flap deflection. Maybe the 15 degree deflection is more than what's required for a full span flaperon?

(Of course, it's also worth recognizing that the largest load on the flaperon servo might not be aerodynamic at all, but from a hard landing.)


Thanks,
Chung

[thelocust]

For what it's worth, I use HS-85MG's for flaps on my 3m Aegea wing and on the elevator and rudder of my EZ Bubble Dancer and on my slope trash. They really can take a beating. I stopped buying HS-81's and their MG version because I had one to many stop centering.

The Hitec thin-wing servos (HS-125, to be specific) I use for the ailerons on my Aegea wing. I did see one of those strip out on a Jaro Mueller Ellipse a few weeks back when used as a flap (with nylon gears).

[aeajr]

I have had stripping problems on the HS-125s.

I would expect the 85MG woudl be fine for your plane.

[stumper]

[QUOTE=chlee]Hello all,
I'm thinking of building a 2-meter sailplane with flaperons (Aegea with Barnes-style construction) and am wondering if the HS-85MG would be sufficient for this purpose. The HS-125 is of similar torque, and the stronger 225 is much too thick...

The reason I'm asking is that I read this post by Dr. Drela:
http://www.rcgroups.com/forums/showpost.php?p=2517672&postcount=2
and got a surprising calculated result that I need to check against actual experience.<<

they are a bit more $$$ but you can't lose with JR's digital 368 servo.. all the power you need for just about any application.. they center well with great holding power.. and what most users never take into account, a 3-year warranty.. unconditional, no questions asked.. can't beat them..

stumper

[chlee]

Thank you all for your replies. I'll take a look at that JR 368 servo, but will otherwise try my luck with the HS-85MGs on my flaperons.

- Chung

[billwolfe]

Chung,

How did your 2M flaperons work out?

--Bill