[NSRCA-discussion] E-Focus Conversion

[glmiller3 at suddenlink.net]

In response to a couple of requests, I'll post here my observations and experience in builing an E conversion of the Focus. I built a focus ARC for electric with a Plettenberg 30-10 and converted another Focus from YS140 sport to AXI 5330 power.  Both systems work well with TP 5300 5S2P packs running in series for 10S.  I've used  Shultz, Castle Creations, Jeti and Jeti Spin ESC's  and I've tried BEC's and receiver packs.   

As for the physical conversion, if you are going to build the Focus for E power, just make the motor box sides longer than the stock kit sides to extend the box forward to where the back of your E motor of choice needs to be and back mount the motor there.  Alternatively, you can use a back mount extension from the standard motor mount box with metal or nylon standoffs available from Hobby Lobby or Esprit models.  

I used the front of the pipe channel from the wing tube forwar to the gear plate to mount the batteries.  TP 5300's fit here by just widening the opening slightly and making a box for them to sit in.  I'll post some pictures later.  

By moving the gear mounting plate the the bottom of the fuse, and flooring roof of the pipe tunnel from the firewall to the old gear plate, a channel is created to route the wires from the motor/ESC to the battery compartment.  The only downside to this arrangement is having to flip the airplane over to change batteries.  You could arrange this internally and have to remove the canopy to access it, but the advantage to having the batteries hanging out the bottom is very good cooling without having to create a lot of internal ductwork and exhaust holes.  

The only other thing I changed was to use longer carbon main gear to add a little more prop clearance in addition to moving the gear mounting plate to the bottom of the fuse.  

This is a very easy conversion which is easy to keep under weight if you are careful.  If I were going to do it again, I'd probably get an ARC kit and use lighter covering than Monokote.  I'd keep the batteries in the pipe channel but set up for some of the newer 4700 to 5000 mah packs that are a little lighter than the old TP 5300's and I'd use an AXI 5330 or maybe try the DualSky ?? ( sorry don't know the designation).  Once Chuck got the ESC problems worked out, his DualSky certainly seemed to have plenty of power and the price is very right!  

Another point for discussion is the use of a BEC(Battery Elimination Circuit).  I've used an HV Bec in several applications from big helicopters to the E Focus and I've had very good luck with them.  It is an easy way to save the weight of whatever onboard RX batt you would otherwise use and you never have to worry about charging the RX pack...  The potential down sides are 1) RF noise (which I've dealt with once and 2) loss of RX power from BEC failure or main battery failure.  RF noise is much less of an issue at 2.4 Ghz and I've only had a problem with it in one airplane before I switched to 2.4 Ghz...I don't know why that one had a problem but it showed up in the primary ground range check.  I removed the BEC and replaced it with an onboard pack and problem was solved.  I bet I could put the BEC back in now that the plane is on 2.4 Ghz.    I've never had a BEC fail and that includes burning out a couple of ESC's for various reasons. 

Sorry this has gotten a little long and rambling, but I thought it was a nice change from "changing the weight rules" and "Momma won't let me judge for two years"<G>



George