Control Line competition model aircraft designed for absolute maximum speed were always functional, bearing scant resemblance to full size aircraft.
In the early days of control line modellers realised that control line provided an ideal opportunity for conducting speed competitions, as speeds could be measured accurately using simple equipment. Knowing the length of control lines (the radius of the flying circle) and timing a specified number of laps of the circle with a stopwatch, flying speed could easily be calculated with sufficient accuracy to separate competitors.
Design of pure speed models was unrestricted except for safety requirements and specifications of size. Three classes were created for engine capacities up to 2.5cc, another for up to 5cc, and the biggest for up to 10cc. Other classes experimented with were pulse jet, and proto speed, in which teamracer sized models were timed over a standing one mile course, commencing at rest on the ground. Proto speed was therefore a test of acceleration as well as top speed, and was occasionally won by an ordinary teamracer.
The noise created by a pulse jet is truly terrifying, guaranteed to turn every head wherever one is operated. But the big 10cc class of speed model scared a few modellers as well, who exhibited a tendency to retire behind solid trees and vehicles whenever such a model was in operation nearby. The thought of possible damage that could occur should the control lines break during flight of one of these projectiles is rather alarming, although it almost never happened.
The pictures on this page:
1. Athol Holtham with a Class 2 speed model at a contest day held at Albert Park in the early nineteen sixties.
2. Bob Neilson's Class 2 Proto speed model, flown for him by Rob Edgerton at the Melbourne Nats of 1964.
3. This SuperTigre 29RV powered Class 2 speed model by Andy Kerr set an Australian record of 170 MPH in the late nineteen sixties, flown on 60 foot monoline. A good view of a takeoff dolly is provided in this photo.
4. Robin Hiern's Class 2 speed model powered by SuperTigre X29 and flown on monoline was an Australian record holder in 1999 at 180 MPH or 290 KPH.
5. At the south Australian State Champs of 2002 Robin Hiern set a new speed record of 284.75 kph with his Profi powered FAI model.
6. Hugh Simons at the World Champs in 2002 where he won the junior section of FAI F2A speed with his Profi powered Profi built FAI model.
Several specialist items of equipment evolved to become standard at speed contests. An electric starter motor (often made from a car starter motor mounted over a big battery) was commonly used for starting engines, even when motors in other classes were started by flicking them by hand. Speed models generally use a jettisonable set of wheels (called a "dolly") for take-off. And to prevent pilots from whipping (leading the model around the flying circle to increase its speed) during their timed runs, control handles were eventually required to be restrained by being placed in a fixed pylon provided in the centre of the flying circle.
A fascinating pursuit for modellers attracted to engine development and technology.
To see some photos of modern speed models as they were at the end of the 20th century, take a look at Robin Hiern's speed photo page.