The beauty of a remote or R/C dethermaliser is that you can D/T the model at will, saving flyaways or a long walk up the paddock.
This is an alternate hack to the BMK line of remote D/Ts. It is made using circuit components from an old Spektrum 6 channel transmitter that came with an Efite heli. Be sure to use full range components so your F/F model doesn’t get away.
The components are housed in a small electronics project box.The bits purloined from the old Spektrum transmitter include the encoder/transmission board, aerial, charge socket, switch and an AAA eneloop battery. The extraneous wires have been chopped off. Binding is done by shorting out the trainer terminals (on the board to the left of the ‘l’ on the battery).On off switch, charge socket, D/T activation toggle switch and aerial mounted on the outside of the box.
The model is fitted with a small RX (I used one of those tiny Orange ones which weighs 2.4g) an HXT 500 servo (6.5g with lead) a single cell lipo (3g 70mah to 8g 250mah) as the servo and RX run fine on 3.7V. An external switch can be included if required for an extra 2 or 3 grams. All that comes out at around 15g or a half ounce. The servo arm protrudes outside the fuse and the D/T line is hooked to it. It is probably heavier than the BMK alternative but still acceptable for a sports model. I fitted mine in a 32″ Vic Smeed Poppet powered by a 0.25cc Schlosser and there was no noticeable change in the flight performance. With a little inginuity a band burner could be set up to eliminate the servo. The disadvantage compared to BMK is that it does not allow the setting of a timer for the D/T.
Alternately you could save yourself a lot of fooling around and just use a regular transmitter and activate the D/T with the gear or some other switch or button. And yep you could probably use the countdown timer to active a timed D/T.
