I bought a Robart Electric Retract Conversion Kit for my TF Mustang at Joe Nall. Wasting no time when I got home, I assembled all the components/ hooked up all the leads and.................nothing. The status light on the retract control box remained red (no signal or low battery). The instructions say to remove a jumper in the Aux Battery receptacle and the plug the battery plug, via a charging switch into that receptacle. The A123 battery I have has two leads, one is a two wire lead and the other a three wire. I normally use the three wire lead for charging and the two wire for the battery plug. Out of desperation I finally plugged in the three wire plug and the system worked as advertised. However it is also powering the receiver and servos as well, even if the receiver switch is off. So....what's up? Why does the retract system require a three wire lead to operate? What is the recommended battery harness setup?

Unfortunately, the retract system instructions offer no battery hook up recommendations. Just says to remove the jumper and use a switch between the Aux Battery and the control box. My hope is somebody reading this forum has gone through this and figured out a fix.

Speed,

Almost everyone I know uses two batteries. Before you install those retracts, read all the RCU treads. There are wing and retract fixes to keep those tracts from twisting. AND they will twist and bend the jack screw mechanism.

I don't have time right now to full explain the fixes, but if you install a second set of housing blocks in the back of each retract, you will keep the mechanism from twisting. This fix is detailed in the treads.

Just received a reply from Robart. The Aux Battery port requires a three wire battery plug to function. Well...that answers that! However, I still need to know how to cut the signal wire so the Aux battery doesn't affect the receiver. Anybody know how that is done?

Chris, many thanks for your input. Can you give me a short cut to the important threads discussing the retract block fix? Amazing I haven't heard about this before now.

Thanks,
Keith

http://www.rcuniverse.com/forum/rc-w...t-arf-136.html post 3391

This shows how another guy did his on robart fw109 gear. Same concept as my fix. I Think we both thought it up at the same time.
As far as wing fixes, the are scattered in the 3 Mustang treads.
' TF 1/5 Scale P-51 ARF Assembly (1ST MISHAP!!!)'
is the biggest one.

In a nut shell, open the bottom of the wing from the wheel hole to just before the aileron servo bay. Expose the spar box. Double all the shear webs with light ply. Double the ribs that the gear blocks are attached to. Run blocks under the gear block and extend them to the spar box. These fixes will distribute the load better and keep the spar box from spitting.

Speed,

I would recommend that you read thru all the Mustang threads. That how we all got the info that keeps of Mustang flying!

Chris,
The retract in the picture you sent looks different than mine, I'll double check.

Yep, I'll do some reading and get smart on it all.

thanks

Yes, the picture is for a fw109, but the mechanism is the same. If you don't capture both sides of the rods the jack screw rides in, the backside will twist.
I put 4 more flights on one of my mustangs today. Last year before the fix I ruined 3 set of robart electrics. Since the fix more than 60 flights no problems.
It is a design flaw. I talked to robart about it last August. I was told that something has to give if there is a bad landing. Let me tell you, t he gear I wrecked were not from bad landings. During a cross wind (crowed) landing the jack screw pivot would pop out of t he holding blocks and twist the back holding block rod. 50.00 to replace that piece.
I may not be explaining this well.

Good luck.

It's amazing that Robart has not fixed the problem with the holding blocks twisting causing the linkage barrel (part that the jackscrew threads thru) to pop out of the holding blocks. I had the same problem on a take-off on an asphalt runway at the Mint Julep in Kentucky meet last year. The motor then ran the entire flight until it burned out.

Down and Locked fixed the problem by machining a new part that combined the two holding blocks into one piece. Has worked perfect since. Now if they could just get an electric motor that is strong enough to operate the retracts without burning out or amping out before the gear cycle is complete.

There are several flyers in my club that have tried the Robart electric retracts on warbirds and all have gone (or are going back) to air retracts because of the problems with the motors and jackscrew. Down and Locks fix below: That is grease that looks like dirt.

Ralph,

I saw your post about Down and lock in the past. Down and Locks conversion is better then Robarts but way move expensive. I have one set from them and have never had an issue. Either way the problem can be fixed. I don't know what what D&L charge you for the fix, for 20.00 and 30 mins you can fix Robarts your self. It just requires a little engineering, but fairly simple.

Chris,

Yeah, Down and Locked charged me $50.00 to install their new holding blocks plus shipping of $18.00. I agree either fix is a lot better than the stock setup. The motor problem is a bigger issue with the electrics. They are going to have to do something about the motors before I purchase any more electric retracts.

Ralph,

I have not had a problem with the motors. Just the mechanism.

Chris,

Maybe our luck will change. In the club I belong to we have had four motors quit or did not have enough power to operate the gear. They all were properly installed, maintained and not damaged by bad landings. In my opinion the motors are simply not powerful enough.

This is what happens when we try to save a few bucks up front. Then end up spending more time and money in trying to fix poor designs. Spend the money from the beginning and you won't be investing in time and frustration.

They just don't hold up as well as other brands. Just my 2cent!