Fun With Flight Boxes and a Lesson Learned in Applied Physics.

[David Davis]

My flight box was getting old and shabby. I'd bought it in an auction in Exeter in about 1997; it was old then. There's a picture of it below in the foreground of a photo taken in 2007 so that was 11 years ago and by 2018 the methanol had started to rot the wood so it was time for a change.

 

​

I had a look on the web and there were three which caught my eye two were advertised with French suppliers and the third with SLEC, an English company I had done business with in the past. I rejected one of the French suppliers because the box was too expensive but chose the second one, produced by a company called Super Flying Models no less, because I thought that the box came fully assembled and painted!

I should have read the small print! Not only was the box a flat-pack, it was unpainted too and twice the price of the English box! Nil desperandum. I got on with assembling the box and found out that my flight battery was too big for it  and the power panel was too small. I cut up lots of pieces of plywood I had handy to make the necessary changes, recycling some parts from the old box, the door knob for example. After several coats of highly patriotic water-based British Racing Green paint everything was wired up and ready to go.

 

​

 

I tried the starter motor, attaching it to the terminals just to the left of the power panel. The terminals on the end of the starter motor are a type of crocodile clip similar to those used on battery chargers. It didn't work! I checked the voltage at the battery. 13 volts. The terminals are fed by two loudspeaker cables each 1/4" thick and soldered to washers which are bolted to the structure of the flight box with a bolt with a countersunk head. This bolt then passes through two steel tubes which the starter motor's crocodile clips grip, and the whole structure is topped off with a cup washer and a nut, painted red and black. I had cleaned the tubes prior to assembly so couldn't understand why the starter motor wouldn't work. I checked the voltage at the terminals. 6.5 volts. In less then a foot of cable, I had only half the voltage!

 

Then the thought struck me! The bolts were the only components I hadn't cleaned! They were oily and rusty. I took them out, left them overnight in petrol and with the help of a rotary wire brush I cleaned them up good and proper.

 

Having reassembled everything I checked the voltage at the terminals. 13V. The starter motor spun lustily!

 

Just goes to show doesn't it?

​

 

Edited By David Davis on 29/05/2018 18:52:13

[Martin Harris - Moderator]

Foggy in France?

Not much in the way of pictures visible - I'm just seeing empty grey boxes...

[David Davis]

Mmm.. the quaintness of the RCM&E's website won't allow me to copy and paste the picture of the colourful Super Flying Models' flight box. So here's what the old flight box and its owner looked like eleven years ago...

and this is the new one, now fully functional.

Edited By David Davis on 29/05/2018 19:18:45