View Single Post
Old Jun 27, 2009, 10:26 PM
Ping is offline
Find More Posts by Ping
Registered User
Ping's Avatar
Joined Aug 2004
483 Posts
Mounting 2200mah Batteries

So the stock battery strap is ok for the smaller 1320 battery. However to fit a heavier 2200mah and maintain your CG you will need to move the battery aft. All you need to add your own battery tray is a soldering iron, gorilla glue, a velcro strap, and a sheet of light plywood. I used 1/8th inch light ply as I had some on hand. The whole mod will add less then 10grams of weight.

Start by removing the stock battery strap. I had originally speculated that this strap was somehow tied into the wing mount but this is not the case. Just tug on the battery strap until it pops off.

Next using your soldering iron we will remove some foam to make room for the battery. I cut to the sides of the fuse and back until you reach hole the aileron servo wires pass through. The depth you cut is important as I will explain later. If you look closely at how the stock battery mounts their you will notice the inclined ramp. I cut down to the edge of this ramp as square along the center line of the fuse as possible.

Next we will cut the plywood tray. Begin by cutting a 2.30"x3.75" (58.25mmx95mm) piece of light ply. You will want to round the corners that point towards the firewall slightly. Mark the center of the ply tray.

Test fit your ply tray and sand the edges if needed. Transfer your center line mark to the fuse on each side. Try and make sure the tray is sitting parallel to the fuse center line. This is important and I will explain later.

Go back with your soldering iron and cut a thin trench for your velcro strap to lay in. This step is optional, but very helpful if your using a thicker strap.

Once your satisfied with the fit of your tray it's time to glue it in place. This is where I like gorilla glue. With a bit of water it will foam and fill in the many small gaps that your soldering iron left in the foam. You can of course use any glue compatible with Z-foam. Regular CA works as does epoxy. Dampen the ply tray and spritz a small amount of water into the fuse. Apply your glue and let dry. Don't forget your velcro strap!

While drying gorilla glue will foam out around the edges of tray. Simply cut this foam away with a knife.

I installed some velcro to the deck to really keep the battery in place. I sand the tray lightly and CA some velcro in place. I prefer to install the hook side on the model and the loop (fuzzy part) on the batteries.

You shouldn't have to modify the canopy to fit, your battery should sit below the sides of the fuse.

If you notice the battery now sits parallel with the center thrust line of the fuse. If you cut everything correctly the tray should be below the center line, and your battery should sit almost exactly on the thrust line. In my opinion this should make aileron rolls more axial.

You should get a good range of CG adjustment with this tray. You can go even further aft if necessary. I tested my gear and I only needed to have the battery touching the edge of the hole cut for the aileron extensions. Optionally you can install a block of foam in the front of the fuse to keep the battery from ejecting through the firewall on severe crashes.

Stay tuned guys as soon as a spare wings show up I'll be adding retracts and reinforcing the wing. I looked today and I can't see any spar in the stock wings! If you want to hit 100mph+ You'll want to add some carbon spars!

I also highly suggest you fiberglass the bottom of the cowl, mine is already broken. Also reinforce the elevator and rudder hinges with tape or blenderm. I didn't reinforce my rudder hinge and I nearly lost it in flight!
Ping is offline Find More Posts by Ping
Last edited by Ping; Jun 27, 2009 at 10:52 PM.
Reply With Quote