- The “A” Class Sharpie and how to build her “K.N.” Part 9 BY H. B. TUCKER
- A Wet Day at the Prototype Sailing Regatta HOVE — SUNDAY, JULY 25th, 1954; Barques, Schooners, and Brigs
- RADIO CONTROL NOTES By G. SOMMERHOFF A series of articles for the modeler with an interest in remote control of his craft.
RADIO CONTROL NOTES A series of articles for the modeller with an interest in remote control of his craft By G. SOMMERHOFF Author of *’ Radio Control of Model Aircraft,’’ Percival Marshall, price 9s. 6d. THE 1.R.C.M.S. CONTESTS AT BIRMINGHAM ates the indifferent weather the contests organised by the International Radio Controlled Models Society at Birmingham on July toth were an outstanding success ; and the nation-wide publicity which was given to the event by that evening’s T.V. broadcast from the Valley Pool was well deserved. For the writer, who had never before attended one of these larger contests, there were a number of interesting lessons to be learned. One lesson was that the model which shows off best on the static tank of an exhibition is not necessarily a model that is going to win any contests for you. This is a lesson which should be pondered particularly by all those designers who intend to use some form of sequence control for their steering. Unless your rudder control is really quick acting you are not likely to do well at these contests. Undoubtedly one of the finest models the writer has seen, and a model which is furnished with the most ambitious radio equipment, is Mr. H. R. Claytoa’s ‘* Geebaa III” (Photograph 1). This model gives something like 20 control operations which are arranged in two independent sequences of the telephone selector type. These are operated by modulated pulses and the length of the first pulse decides which of the two selectors will go into action. As one of its operations, the cruiser can release a radio controlled dinghy and this responds to a keyed carrier signal without interfering with the main ship. But it was generally felt that Mr. Clayton’s steering was too slow. The boat which managed to combine the quickest and most reliable steering with the highest speed was Mr. F. G. Buck’s (Stoke-on-Trent) power boat which was driven by an E.D. 3.46 c.c. engine. Mr. Buck uses a control system very similar to that described by the writer in the July number of this journal. The rudder, which is driven by a small servo, turns to port on a mark, to starboard on a space and remains stationary on a pulses signal of 50/50 mark/space ratio. A small output trans- former is connected into this rudder network and if the 1. Mr. H.R. Clayton (Chalfont St. Peter) with his ** Geebaa III”’ 2. Mr. A. P. Dowsey’s ‘‘ Feanne”’ 3. Mr. E. M. Robinson (right) and Mr. L. combine radio control with a vane steering gear G. Brough a pulse frequency is increased this transformer gives an output in the secondary which (after rectification) pulls in a second relay and thus operates a second control. If the pulse frequency is raised still further a third relay (in series with the second) pulls in and gives yet another control. Mr. Buck’s transmitter was pulsed by a Siemens High Speed relay of 3,400 ohms which was rigged as a buzzer and slugged by a capacitor of 16, 25 or 50 mfd., according to the pulse frequency desired. The mark/space ratio was adjusted by a 10 K. potentiometer in series with this capacitor. This exceedingly simple system has proved to be exceptionally effective and reliable. After witnessing the performance of this boat the writer strongly recommends this system for high-speed power boats in which no more is desired than efficient and reliable steering combined with good engine control. Mr. Buck won the first prize in class “‘ C”’ and it is interesting to note that the first prize in class “‘A” (equal with Mr. P. Cummings) was won by Mr. A. P. Dowsey of the Tyneside Group with yet another control system of the type just described. Here we had a progressive rudder control operated by a pulsed signal of 3 pulses per sec., and combined with this there was a sequence of additional controls which was operated by a pulsed signal of 9 pulses per sec. The pulses were given by a revolving pulse drum. The boat was powered by a converted 12 volt, 2 amp., electric motor and there were 2 speeds forward and three astern. His cruiser ‘‘ Jeanne’ is shown in our second photograph. Another member of the Tyneside Group, Mr. E. C. Kennedy, had an interesting innovation to show in the form of a Kitchin Rudder (see our January 1954 issue). A low frequency pulsed signal of variable mark/space ratio gave a progressive control over the “ steering” movement of the buckets and a high frequency pulse gave a sequence control over the “ speed” and ‘“‘ reverse ”’ movements of the buckets. A small telephone selector was used for this whose coil had been rewound with 36 s.wW.g. wire to suit the boat’s voltage. A number of radio systems used reed units of 3, 4 or 6 reeds. This was almost standard equipment for the sailing yachts, but unfortunately the weather did not give these boats much of a chance. The writer was interested to see that Mr. Robinson and Mr. Brough (Newcastle-on-Tyne) used their radio gear to control the setting of a vane steering gear. But as there was not enough wind to move the vane, the system could not be put into effective operation (Photograph 3). The results of the contests, for which there were 42 entries, were as follows : Class ‘‘ A’ (Miscellaneous power) First P. Cummings and A. P. Dowsey Third J. Gascoigne Fourth J. R. Sanders Class Class “B” (Sail) First A. C. Aldridge Second G. Honnest-Redlich Third C. G. Hogg “C” (1.C. only) First F. G. Buck Second J. D. Taplin Third W. S. Warne 4. Mr. A. Wilson (Birmingham) with his M.T.B. which fires a gun and contains a home-made (!) telephone selector 5. Mr. F. R. Sanders (with his “ wave master’’) whose interesting control system was described in our March issue 6. The late Mr. A. T. Trotters’ beautifully finished “ Ivy May ” uses M/S steering only
