There are plenty of guys that have ran them on 6v. And futaba used to say it was ok but deleted the thread. I believe the reason futaba does not recommend them anymore on 6v is that the gears really can’t handle the torque and will strip if you stall and or load the servo hard. I have seen several fail gears running regulated on light to moderate loads. The gears really are not very strong and can strip pretty easily.

Indeed one of the aileron servos had a stripped gear (the owner
had a replacement set that came with the plane).

What would be a good replacement that can handle a LiFe pack?
The plane is a 96" P47 (~31 lbs).

Originally Posted by lrb75

Eneloop batteries are great for low drain applications like a transmitter. A larger plane with a bunch of servos puts too much strain on the little AA sized cells which have a pretty high internal resistance, so much higher voltage drop under a given load.

^^^^^^^^^

You should check out the ProModeler line of servos. They have a large selection of standard servos to choose from. The torque listing is for the 8.4 max voltage they can handle so if you are running a LiFe pack you will need to reference the specs listing to see the torque at 6.6 volts.
http://www.promodeler.com/standard-servos.aspx

Originally Posted by Philkoury

You should check out the ProModeler line of servos. They have a large selection of standard servos to choose from. The torque listing is for the 8.4 max voltage they can handle so if you are running a LiFe pack you will need to reference the specs listing to see the torque at 6.6 volts.
http://www.promodeler.com/standard-servos.aspx

They seem nice servos. I presume that a digital servo rated at 120 oz-in would be enough for a 1/5 warbird?

I put hitec D645’s in all my warbirds.. 180oz of torque and metal gears.. also High Voltage.

Originally Posted by ululi1970

They seem nice servos. I presume that a digital servo rated at 120 oz-in would be enough for a 1/5 warbird?

I would think so, easily.

I am using the DS130DLHV in my 1/5th scale warbirds.

Originally Posted by 3DJP

I put hitec D645’s in all my warbirds.. 180oz of torque and metal gears.. also High Voltage.

I'm impressed with the newer Hitec D-series servos. Just another note on those also, the D-series now have a 25t spline count, which is compatible with Futaba style arms, so the D-series uses Futaba arms as well.

I have a few models using D's and several HS645's in my planes, and they're still going strong. The D645 would only be better then it's predecessor I would imagine. I don't think you can go wrong with them.
Hitec in general has great service as well.

I found two new Power HD LF-20MG in my shop. They are rated
at 20 Kg-cm @6.6V. I got them from Aloft Hobbies a while ago, but never used. I was thinking using them for flaps, and going with ProModel or Hitec for ailerons and elevator.
Any thoughts?

I've had excellent results with Nixx packs from RadicalRC. Have been a satisfied customer of Dave's for years.

The flaps are probably a good place for the PowerHD's. I had a few problems with the PowerHD's, and will probably never use them for a primary control surface again, but flaps are fairly safe it would seem.

My ordeal with the PowerHD's was I thought I'd give them a try, and I did, and it didn't go well. I now have 10, NIB LF-20MG's, and 4 used, and 3 fried. I'll probably sell them in an RC car forum. I won't sell them to a flyer. I swapped them back to Hitecs and never looked back.

Your idea about flap servos should work fine though I would think. They do/did look like a quality servo... and were smooth and fast as they should have been. Maybe mine were a fluke, but I know of others using the very servos successfully too. I'm just gunshy about them I'm sure.

Why would a servo you have no confidence in be okay for flaps? The flaps are a control surface just like the elevator, ailerons, and rudder. If you are setting up for a landing and only one flap extends things will get interesting.

Originally Posted by Philkoury

Why would a servo you have no confidence in be okay for flaps? The flaps are a control surface just like the elevator, ailerons, and rudder. If you are setting up for a landing and only one flap extends things will get interesting.

Very interesting!

It really doesn't matter does it? Take it for what it's worth.

All things considered, a flap servo gets a fraction of the use and forces that a primary servo does. 99% of time they go up, they go down, and the plane in either state of flight isn't honking around with maximum force applied... and flap servos are not being constantly used, with force. Not primary to overall control of the aircraft in flight.

If flaps are just like an elevator, ailerons, rudder, why is it they're only used when taking off and landing? True they are a control surface, but not primary to the overall control of the plane, and definitely not through the whole envelope of flight.

Yes it would get interesting if one flap didn't deploy. Any pilot worth his salt would know to pull up the deployed flap, land the plane, and not try to land the plane with only one flap deployed.

If a pilot were to attempt to land a plane with one flap deployed, that would be interesting... the scenario I'm describing wouldn't be nearly as exciting.