Last year I was fortunate enough to visit the electric fly-in at Winchester and witness all of the wonders present, including Kevin Saunders' EDFs (Electric Ducted Fan) and his launching system. Rather than the usual angled ramp with parallel dowels to launch the model up from the start, Kevin's clever launch system is based around a launch dolly.
For some reason I took it upon myself to build one for the club. In fact I built two because... well, as much as anything for comparison but also I found that, whilst conventional models were fine on the Saunders launcher, a flying wing type with little or no fuselage underneath the wing tended to foul the wheels of the dolly, making it difficult or impossible to hook up.
My (Andrew's) Saunders launcher is a 1/4in steel plate with parallel strips of 1.25in angle iron screwed to it, forming a channel down the centre line. A spring return see-saw type pedal when depressed, allows a short shaped bar to pivot, so releasing the wire loop. On the other end of this wire, about 28 - 30in away, is the hook which connects to the launch dolly.
| Line Connected | Released |
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The launch dolly is basically a pair of wheels about 8ins apart on a 10swg axle to which are attached a couple or three other smaller wire bits, one for the hook on the model and two more to allow the attachment of the wire from the foot release and a length of cord to connect to the end of the bungey.
The main thing that held me up was the bungey. For me, all the 'normal' outlets were too costly and, not knowing if anyone was going to use this except for a few (who even then still may not have any models fitted with a hook) I had to find a cheaper alternative. As luck would have it, In-Excess in Purewell saved the day. £7 lighter and, armed with 10m lengths of 8mm and 12mm bungey, I was in business. I taped a hook to the bottom of the Quisling and headed off to Stanpit.
For those of you who don't know the Quisling, it is a rubber, 2-channel, almost brick - excellent for those of a nervous disposition trying out a new launch device with rubber as thick as your thumb stretched to twice its length. A couple of tasty moments, but success!
The wooden launcher,
based around the device featured in the March 2003 edition of
RCM&E. was again built thanks to In Excess, using two lengths
of approx 3/4in diameter dowel. The magazine instructions suggest
using an A frame near the ground stake, but I think that would
only be necessary for heavier models that we are unlikely to be
launching at our public sites.
If you would like to try the relative assurance of either release system to launch your model, then just ask; I've probably got them both on the van if I'm flying. The benefits of the fast bungey release are that the model is well up to flying speed before you apply power, thus allowing a minute or more extra flight times, your launcher mate doesn't have to risk a twisted ankle trying to avoid Stanpit's potholes, and you are not at the mercy of his loose sloppy grip or run, stop, throw technique (we've all seen them) that sends your stand off scale jet prematurely earthwards.
All I need to do now is improve my flying skills and finish my Supermarine Attacker. Having said that, anything suitably hooked will launch, from a 26in speed 400 pusher to a multi-motor prop or EDF job. Just adjust the tension and stand well back.
Oh yes, make sure you turn the receiver on before hook up. The expression "user beware" comes to mind.... (Sounds more like "Voice of experience" to me! - Ed)