Dave Smith on Formula 21 speed
We are very lucky that Dave Smith has been in contact with some details of his Formula 21 speed models.
Dave Smith has won the UK Nationals a higher number of times than a lot of people can remember, both in class at F21 and in outright Open Speed, Dave has followed a gentle evolutionary approach to the F21 class and that has bought the great results mentioned.
Dave has a few words to say about Formula 21 below
FORMULA 21
I have flown this class continuously for some 33 years up to the National’s 2019, due to health issues I have now retired from high tech Speed.
Another Nationals win for Dave Smith
I used the NovaRossi 21 engine exclusively during this time. (metallurgy and quality of design and manufacture are World class).
Dave Smith asymmetric Formula 21.
My major modification consists of machining the exhaust to 190-195 degrees, making a new venturi with wick feed etc.
Initially I followed the F2A route of high revs and large volume pipes, however I manged to go faster using my home made 90mm radius carbon single blade propeller and low volume pipe.
Dave test running Novarossi 21 at the 2019 Nationals
Obviously over the years I tried many configurations and coupled with many bench tests I managed to set many consistent high speed runs which has given me much satisfaction.
I used 20 percent nitromethane and various grades of the NovaRossi Turbo glow plugs plus of course a sturdy drop out dolly complete with nylon wheels.
My current British record of 179.47mph was set on the thick 0,45mm lines, 2 lines at 58 ft 0 ½” requires approximately 3 HP to get to 180MPH, my engines hit between 32-33K in the air.
Here is a video from a meeting in 2011 of my F21 model flying in competition.
There is a plan of one of my early asymmetric designs and write up in the Aeromodeller in 1993.
