I had a .61 Evolution sitting on my shelf looking for a plane, and as chance had it, a club member won a DAGO Red and did not really want it, so I am now own a DAGO Red ARF. The question I have is regarding the retracts that come with this plane. They are mechanical, and after discussing this with some club members and they were saying that if the retract binds up for some reason it can quickly drain the battery, which could lead to an unscheduled (and rather abrupt) landing. Is there any way to have a second battery to power the retract servo? I do not really want to change out the retracts.

Thanks,

Rob

(It has been awhile since I posted, what happened to spell check? I could not find the option.)

Make sure the mech. retracts are working properly, charge her up and go flying. You only use the retracts twice during a flight, take off roll and down leg, base to final. There should be set up instructions with your P-51 for the retracts. Share a maiden video with us if you don't mind. Good luck.

What can happen is if the gear bends and gets hung up; ie can not fully retract the servo is constantly drawing current attempting to zero itself. Use a good 6 volt battery and check your gear function every flight. Also ensure when you initially set it up that you set the EPA ((End Point Adjustment) must have a computer radio to do this) so that it is not trying to over retract or extend the gear.

Now to answer your question; yes, you can set up a battery for your retracts. First off you need to know what the three wires for your servos are. If you run Futaba gear the white wire is for signal, black ground and red is positive (4.8-6.0v). With Hitech and JR the signal wire is Yellow, ground is brown, and positive is red. Do not cut these wires. Get a 12-24 inch servo extention to plug into your reciever and another "on/off" switch. Cut the pos and neg wires on the extention and splice in the on off switch. Attach a battery to this switch as normal. The signal will still come from the reciever but power will not be drawn from your main battery.

EDIT//

I have modified the scematic to the specs Pettit mentioned.

You have an error in your schematic.

You need to cut the positive lead on the retract servo but not the ground lead.

That has to be connected to provide the output signal to the servo. Without it, the servo will not move.

Also, end point adjustment does nothing for retract servos. They are 180 degrees--no more, no less.

I have several planes with retracts, mostly mechanical and one air. Sure it can bind up but it's very rare if you set them up right. Been using them for years and also a few WM P-51's. Now i would remove those retracts from the plane and put in some epoxy under the mounting blocks and secure them up better than they are. I do that on all of mine so they don't rip out. Retracts are no more a problem than anything else on a plane. Having an additional electrical system for retracts on a40 size plane is a waste of time, money and effort. Just not needed.

Your putting a Clydesdale before a Radio Flyer here and making a big issue over nothing. IMHO if you do this you will be creating more problems you would not have in the first place by simply setting it up right. Like he said they are not porportional servos and you cannot adjust to fit like an elevator, aileron or throttle.

The adjustment comes from where you attach the rod to the servo arm. Most of the time it's on the outside hole of a standard arm and also where the arm is place on the spline of the servo. Don't attach them both at once. Set one retract up first, get it going right and see how it works and then do the other. Cannot have the rods to long either or they will hit each other when the servo moves

If you measure the distance the retract mechanisim moves from full down to full up, and set up the linkages so that if you draw a straight line through the center of a servo wheel, the line goes through the connectors for the pushrods, and the connectors are the same distance apart as the mechanisim push rod moves, you are golden. MinnFlyer has some drawings if that doesnt make sense and he talks about it in his review of the Hangar 9 Miss America.

I agree with Cyclic, you are making it more complicated than it needs to be and adding unneeded weight.