Battery Boxes for Electric Profiles

[Mike Griffin]

What is a good way to mount the battery under the outboard wing on a profile?  RSM used to make a laser cut plywood box that was cut for the contour/airfoil and was mounted to the bottom of the outboard wing next to the fuselage but not sure if they are still available.  What other ways have some of you come up with to mount the battery on a profile.  The nose on some models is too short to mount there and the one I am currently building falls into that category.  Any pictures you can share of your techniques would be appreciated. 

I am trying to build more electric models.
Thank you
Mike Griffin.

[Dennis Adamisin]

Hi Mike
I have designed 41 electric conversion kits for Brodak.  Many of these are "Universals" that can be adapted to different designs, the rest are designed for a specific airplane - and some can be adapted to other designs. Check out the Brodak site for more info - or drop me a line!

[Mike Griffin]

Hi Mike
I have designed 41 electric conversion kits for Brodak.  Many of these are "Universals" that can be adapted to different designs, the rest are designed for a specific airplane - and some can be adapted to other designs. Check out the Brodak site for more info - or drop me a line!

Thank you Dennis.  I will drop you an email tomorrow.  Can you PM me your email address, I cannot find it.  Meanwhile I will check out Brodak.

Thank you
Mike

[redout]

What is a good way to mount the battery under the outboard wing on a profile?  RSM used to make a laser cut plywood box that was cut for the contour/airfoil and was mounted to the bottom of the outboard wing next to the fuselage but not sure if they are still available.  What other ways have some of you come up with to mount the battery on a profile.  The nose on some models is too short to mount there and the one I am currently building falls into that category.  Any pictures you can share of your techniques would be appreciated. 

I am trying to build more electric models.
Thank you
Mike Griffin.

Well you didn't say it had to be pretty 

Not quite under the wing but it worked for me, considering CG requirements.

My first attempt - ARF Flite Streak. I secure the works with a big rubber band around the outside.

I hope others post photos of their solutions because I have always wondered about this too.

[Brent Williams]

Roger Kramar used this lightweight, effective method to build a battery box on his Pathfinder.  Very slick. 
Thin K&S aluminum sheet cut into strips and formed into a cage to hold the battery.  Four small screws hold the cage to the fuselage. 
Centrifugal force keeps the battery in place, and a velcro strap is used for added peace of mind.
 

[redout]

Brent, nice set-up.

Did you have to add weight at the rear to get the CG right ?

Richard

[Brent Williams]

I think Roger has the CG set per the Pathfinder plans and might have added 1/2 oz to the rear to trim it to taste.

[Perry Rose]

I've used Dennis/Brodak conversion kits on several planes. They work well.

[Ken Culbertson]

Centrifugal force keeps the battery in place, and a velcro strap is used for added peace of mind.

And if you have a brain fart and, for reasons only my shrink seems to understand, put the battery where you would normally put a tank, the place it will "keep it" is about 20' outside the circle.  Hopefully down wind, they tend to flutter down when you lose the battery upwind.  Please don't ask me how I know.  That cute little battery weighs 10-15lbs in a corner - do it Roger's way! 

Ken

[redout]

I think Roger has the CG set per the Pathfinder plans and might have added 1/2 oz to the rear to trim it to taste.

O.K. so it makes sense that on larger models, like the Pathfinder ( with higher tail moments ) that putting the battery wholly in front of the leading edge can be done without having to add much ballast to the rear to get the CG right.

But it seems the problem of battery mounting becomes more difficult when the battery has to be sited partly behind the L.E. on smaller models in order to get the CG back far enough without having to add extra rear weight.

[Ken Culbertson]

The LE does not have to be continuous in order to be strong enough.  If you have not finished the wing you can carve out a section to keep the battery horozontal and beef up the spar.  I have done that on several IC planes to accept a longer tank and never had a wing fold.  In most cases you can just cut the top half of the LE and build a shelf like insert.
The picture shows IC but I later converted to Electric and used the same cutout for the battery.  It too was on the wrong side.

Ken

[Brent Williams]

O.K. so it makes sense that on larger models, like the Pathfinder ( with higher tail moments ) that putting the battery wholly in front of the leading edge can be done without having to add much ballast to the rear to get the CG right.

But it seems the problem of battery mounting becomes more difficult when the battery has to be sited partly behind the L.E. on smaller models in order to get the CG back far enough without having to add extra rear weight.

On a glow powered airplane, you wouldn't put a giant, heavy .60 sized RC engine on a s-1 ringmaster, or fill up an 8oz tank when you might only need 3oz for the flight, ect. 

On electric airplanes, it's equally important that you use appropriately sized components for your airplane (motor, battery, esc.)  Don't carry more weight than you actually need.  Avoid using a battery or motor that is radically larger (and heavier) than your actual needs. Don't build the structure of the nose of your electric plane as If you are mounting a glow engine.  If you don't know what you need, post a description of your airplane and get some guidance.  There is certainly a lot to consider when you're getting started, but there are a lot of examples of working combinations for just about any general stunt plane out there.

[Teodorico Terry]

I built a little Brodak Shark 402 as an electric model over the winter and made a few simple changes to accommodate the battery, ESC and timer. I did lengthen the nose by 3 inches to accommodate batteries that I already had. To compensate for the longer nose I moved the stab back by about 2 inches. In the nose section I created an opening which allows the battery to be partially recessed into the fuselage.  I have enclosed a couple of photos which show what was done. The Shark had a very short nose to start with and hence why changes were needed. I will be building an Oriental soon and it appears that its nose is long enough to accommodate the equipment so the changes should be minor.

Good luck,

Teo

[jerry v]

Brodak kit Ringmaster S-1. Underwing battery mount. If you can shift the battery, you don’t need extra weight to balance.

Jerry

[Jim Hoffman]

I built a profile Pathfinder and used the 3D printed motor mount from Tom Morris / Okie Air with the objective of a clean E-power profile installation.  I am most pleased with the result. 

I stretched the nose as needed (about 1.75”) to package everything, including the 5S battery.  The resulting model has maybe ¾ oz. tail weight in its current flight trim.

I built a battery and ESC box as copied from photos from Tom Morris a few years ago.  The removable balsa cheek cowl on the inboard side is located with steel pins and retained with small rare earth magnets.  The motor start button is located on the Hubin timer PC board.  There is no arming plug because the battery connectors are readily accessible by pulling off the hatch.