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        Discussion Do the retracts on a H9 P-47 really need 260 oz of torque?

#1 xray328 Dec 28, 2012 03:53 PM

Do the retracts on a H9 P-47 really need 260 oz of torque?
 
Hey guys. I got a .60 size H9 P-47 for Christmas and the manual recommends the JR 791 retract servo. It's $59 and produces 260 oz of torque. Is that really necessary? Seems like overkill to me. This is the first plane I've had that uses retracts but I can pull the linkage pretty easily by hand. Is the high torque just to keep them from collapsing on touch down? How much torque do I really need? Thanks!

#2 cyclops2 Dec 28, 2012 06:10 PM

The cheapest L G set by GWS all have a simple locking mechanism. No kick back force to the servo.

Decent gear has that feature.

Hook up a standard sized servo . I would test it with a weaker one. Rather ruin a servo.... than brake the wing spars.

I think the overkill is a typo error..

Did you notice the >>>>>>>>>>>>Do not use 6.0 volts....................... ?? Has to be a very old servo. Go with something that can handle 6 volts or better

On the web site they do state that it has fully locking up & down positions for the servo.........O K.....As they state you MUST CAREFULLY adjust the servo arm hole / throw and the rod . ...........Click on their Resources Tab of the plane...

You now know how strong of a servo you will need. :) Enjoy

Rich

#3 Lifer Dec 29, 2012 05:45 AM

Spectrum has a retract servo that you can adjust the speed and end point. I think it's the AR 2000. The torque is for moving the gear while in the airstream. The servo has a locking device in the extended and retracted positions; servo torque has nothing to do with it. I have used both types, and the Spectrum is my first choice. I thinks it costs less than $30.

#4 cyclops2 Dec 29, 2012 06:56 AM

Lifer

That sounds great, if it does both. Saves a lot of needless seperate pieces & wires jumbled up.

Ray

Maybe you hold off till all the landing gear servos are posted ?

Rich

#5 cyclops2 Dec 29, 2012 07:15 AM

Web surf
 
Adjustable landing gear servos.

Lots of postings about different types of operation & the pluses & negatives of each type.

Interesting

#6 xray328 Dec 29, 2012 11:24 AM

Looks like its the A7000...very cool:

http://www.spektrumrc.com/Products/D...odID=SPMSA7000

#7 V2rider Dec 29, 2012 04:38 PM

Quote:

Originally Posted by xray328 (Post 23651176)
Looks like its the A7000...very cool:

http://www.spektrumrc.com/Products/D...odID=SPMSA7000

Love it. As much as I dislike mechanical retracts I think i may have to give these a chance. I thought I was going to have to wait for the new Robarts and pay through the nose. :)

#8 scootrb4 Dec 29, 2012 07:33 PM

I grabbed one myself I have a couple of builds in the pipe. I try it on one. Thanks

#9 Lifer Dec 30, 2012 06:11 AM

Thanks for locating the right name! In any case, they look really great on a 5 second cycle. Best regards!

#10 xray328 Dec 30, 2012 12:22 PM

Got one yesterday. Apparently my Futaba 7CAP doesn't support servo speed....

#11 scootrb4 Dec 30, 2012 12:55 PM

Quote:

Originally Posted by xray328 (Post 23660689)
Got one yesterday. Apparently my Futaba 7CAP doesn't support servo speed....

You can get an inline potentiometer to slow servo speed

#12 ncflyer79 Jan 01, 2013 07:22 PM

Just get a set of electric retracts for the FMS 1700mm thunderbolt and some 5mm struts and drop in to use. Easy to do and will beat the mechanical retracts all to crap. Awesome plane and is my goto Sunday flyer

#13 Steph280 Jan 15, 2013 03:16 PM

I tried that spektrum servo, as well as the Hitec HS75, JR RT88 and Futaba 136G, only the JR791 was able to pull up the wheels reliably every time. With the other ones you'd have to put the plane into an inverted stall, cut the power, flip the switch while plane is inverted, then the wheels will retract.

This is the same also for my H&M FW-190 and Spitfire. 3 years of weekend flying and hasn't failed me yet. Who says mechanical retracts are not reliable?

#14 edwin1 Jan 15, 2013 06:19 PM

I have 7 years on my mechanicals, using JR791. Got three planes with them installed. The Hitecs I tried at first kept stripping gears.
Edwin


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