A battery wing?

In my thoughts on endurance flying to obtain maximum aerodynamic efficiency I considered putting the batteries into the wing.

To take this concept further I purchased seven 1000mAh A123 cells cheap from Ebay.

 

Would it not be better as say a carbon spar? then wrap the cells in insulation tape?

 

Blimey those cells are cheap! 

A 12" balsa/depron/balsa "battery box" spar with the batteries alongside.

 

Simon

How about some cooling holes ? Just a thought !

Myron

Cooling could be problem but if I can keep it below 10 amps (10C) max it should limit the temperature rise.

The basic wing structure. Now to see if all the RC gear will fit in.

The tail boom (a no3 section of a £1 Whopper fishing rod!) and one aileron servo.

At the moment it looks like some sort of sting ray!

 

More progress. The centre section servos and radio 'built in' with the RH tip in place.

I am waiting delivery of the ESC before I build it in with the motor. The generous dihedral is to compensate for the lack of fuselage side area.

Slow progress as everything has to be checked and tested as the build progresses.

The centre section is part skinned and the tail boom fixed with the elevator servo mounted on the end.

The rest of the tail surfaces will be just 4mm sheet Depron.

A test 2 cell spring contact battery pack It drives everything ok and does not appear to have any difficulty supplying 10A, so two sets in parallel should have no problem at all.
.

It'll be interesting to see how she flies Simon. Even though that elevator servo is very light its an awful long way back!

 

BEB

BEB

Yes indeed but I have set the battery spar (with its heavy cells) at 25% chord (in front of the CofG?) and the motor itself will have to be far enough forward for its folding prop to clear the wing.

I trust all of this will counter the tail servo weight.  

A slightly usual plan form but as this is not an aerobatic model the fixed area is big in comparison to the elevator.

 

A front view showing the thick under-fin containing the servo but all other surfaces just 4mm plates but with carefully profiled leading and trailing edges.

Hi ,

Re battery wing i remember reading an article by a guy whom supposedly designed the 1st lipo battery . In the article he shows how he sandwiched ceiling tiles and aluminium foil and weighted them down , And after charging could power a 12 volt bulb . He also had drawings on his idea of making a foam wing which would also be his battery . I think i still have the article some where  

Stephen

Ceiling tiles and aluminium foil?

I am not sure of the chemistry in such a layout but it would not need to have a very high power density if it used the entire wing area.

Any chance you could find the article?

The 1700kV Blue Wonder motor on the 2 cell A123 and a 7.5x4 prop draws 5.5 amps. Well within my limit of 10 so the prop diam can go up a bit.  

For minimum frontal area the 26mm outrunner motor bell is the ruling diameter.

The basic folding prop mount has been reduced to this diam and the 'spinner' made up with Depron. The position of prop retain pins dictated the rather bluff profile.
In the Battery Wing itself the motor will be mounted on the end of a 26mm diam Depron 'tube' projecting 70mm from the wing leading edge with the ESC inside.
 

A short video of the Battery Wing's motor running on the 2s A123 battery.

Nearly there!

The motor 'tube' temporarily in place.

 

The 'battery box' spar will have a 'floating' spring at its centre to apply pressure to both 2S packs.

To ensure good conductivity (spring steel is not a particularly good conductor) it has a flexible cooper braid soldered to each end. It also acts as the negative power connection. I have still got to engineer in a power on/off switch and a charging socket.