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A bitsa radio DT system for free flight models

I was getting fed up with long retrieves in windy weather, digging models out of trees and wading about in lakes. A radio DT (RDT) seemed the thing. Whilst there are commercial devices that might do the job, the idea of a homebrew caught the imagination.
A quick delve into the BMFA rulebook gave the following recommendation:-

The BMFA Free Flight Rule Book para 3.1.1 suggests.....'that a single transmission for the purposes of DT is allowed for free flight models. The rules disallow transmission on 27/35/40MHz and recommends use of the 2.4GHz frequency'.

A 2.4Ghz Futaba RF module was procured (£30) together with a Phil Green encoder (£10) which supplies the relevant servo signal. An enclosure, a push button switch, an on/off power switch and a 9v pp3 completes the TX components and half an hour with a soldering iron hooks everything up. The airborne system is a Lemon DSM2 2.4Ghz receiver (£8) powered by a 50mah LiPo . This drives a 1.8gm nano servo via a mouse trap. The airborne system weighs 6-7 gm and is shown below. The battery shown is 120mah 1s and was replaced by a 50 mah 1s for flight testing.

Hook up TX schematic is shown below with a parts and supplier list:-

The system has found duty in a free flight dlg which will be tested at Luffenham at the Area events. If you are interested in this, find the PMFC flag and ask for me.

Ian Middlemiss
Feb 2016      contact@peterboroughmfc.org