Remote Electronic Control for F4B
(An article for Aeromodeller magazine 1999)
I had been flying my F4B models on the ubiquitous three line system for many years, but not so recent developments in Europe and in America have convinced me that two line operation of the model coupled with electronic signals sent down the lines is the future of F4B - Remote Electronic Control. I was able to witness such systems first hand at the 1996 F4B World Championships in France and although not completely infallible they were pretty impressive.
I have always been in favour of keeping the control system of scale models simple and have doggedly stuck to the idea of doing it my way, e.g.; using three line control for the engine and supplementing that with a third auxiliary control also operated from that same bellcrank. A fourth control (Drop) can be adapted to operate from a quick dab on the down line, it works, but its not independent proportional control and the flight judges know it ! Their combined scores could total up to a maximum 1300 points, but I usually score in the 800-900s (*see note below). My preference for WW II fighter aircraft means that there is always a need to retract the undercarriage, at the moment mine remain fixed in the extended position and as a consequence I loose 10% of the flying score.
Note: Under the latest revised rules the percentage deducted will increase !
British fliers have developed various electrical systems over the years, methods vary, but it generally requires the pilot to carry a relatively high voltage battery on his person and to send the voltage down insulated lines, thus operating an electric motor on the model which can either be fitted with an arm or a cam which in turn may control different mechanical functions. These systems rely in some part on the manual dexterity of the pilot who must switch or pulse the on/off switch to achieve realism, unless of course a single pulse will suffice as in the case of bomb release.
I have, for more than a year now, been experimenting, I have built and tested numerous rigs and in the process have accumulated enough wire/LEDs/transistors/resistors/ diodes/ motors/gears to qualify me as the next Heath Robinson. But I am not convinced that the final result would instill in me the confidence to produce a realistic high scoring flight for the judges. That is why once again I flew my FW190 at the 1998 Nationals and not my new Curtiss P-40 which has four extra functions.
We have had home based fliers who have appeared on the scene with modified commercial Radio outfits similar to the units that the Americans favour, these allow the electronic signal to be sent down insulated lines and they seem in some part to have had success. I therefore set about trying to obtain such a modified R/C set.
An article appeared in a British model magazine (no connection with Nexus) describing just such an outfit and though written by an American gave an address for a British company who would make the necessary modifications. I wrote to them and in their reply they stated that although they had said that they could make the necessary modifications, they hadnt said that they would make them !
My first dead end.
I have since contacted a well known and long established radio kit producer and his response was to ask for 12 Pounds per hour to develop the system ! (fortunately for me I was all-out of blank cheques). Further leads have put me in touch with electronic experts who will gladly spend hours telling how they have special Chips at hand and the sine wave generated by DX chip gives pulselogic milli amp and so on and so on..... the bottom line is, it seems to me, that no one is able to produce what I need.
Or is it ?
Since my visit to France I have been in regular contact with Vladimir Kusy (now the current World F4B Champion) and have through my efforts to obtain the scale documentation for his Percival Proctor IV (also wrongly reported in the other mag), accumulated one or two favours which I decided to call in. I wrote to him explaining my problem and asked about the possibility of obtaining a similar unit to the one that he and other Czech fliers use. His response was swift and positive.
The system used by both the Czech and Polish fliers is a very neat system and occupies very little space. About twenty units have so far been produced and all work without problems. At the pilots end, the transmitter (which measures 3 1/2 x 2 1/2 x 1 1/2 ) sits on top of C/L handle. The handle has to be made from a non-insulating material, likewise the bellcrank must also be made from a non-insulating material. The very small receiver can accommodate 4 servos.
(Photo's, Vladimir Kusy)
The Transmitter provides the following functions :-
1) On/Off switch
2) LED power indicator
3) A three position switch for flaps (0, 15, 30 degrees)
4) A two position switch (Drop or Undercarriage)
5) Thumb controlled Potentiometer (Throttle)
6) Press button Microswitch (Drop)
Acquiring this system meant I could now confidently adapt the functions on my P-40, which had a three line bellcrank, but with the acquisition of the Czech system the operation of the model should be so much easier. If I thought I could safely take a 7 lb P-40 Kittyhawk through aerobatic manoeuvres then I might continue to fly on three lines, but that is not the case.
Remote Electronic Control is used by most serious F4B Control Line Scale fliers around the world. I believe we need to take advantage of every technical advancement available to improve our flight performances.
Electronics are not the singular domain of the Radio flier.
* Flying the P-40 Kittyhawk at the British Nationals 2000 my best flight score was 1111 points.