Small jets w/o undercarriage should be launched at a high speed, as ducted fans gain efficiency with increasing speed, while they show poor performance at low speeds.
More or less a standard practise today is to launch such models with the help of a catapult (bungee). This catapult is a strong rubber, that is pegged at one end, and held by a pedal at the other end of the sretched rubber, with a short help line.
The model is attached to the rubber and placed on smooth ground, like grass. Pushing the pedal, the model is horizontally accelerated by the rubber and starts climbing on its own.
Such a catapult is available now, ready to use.
Try it, it is the safest way to launch your Jet, and very comfortable too.
We deliver to you the best rubber we could find on the world market. No cheap Nylon woven rubber strands known from DIY stores, but protein free, UV-stabilized natural rubber, which is coloured in dark grey for better UV-protection.
The rubber may be streched to 700% of its length. It fails at 850-900%!
Typically you may want to strech it between 200 and 550%.
To choose the right rubber check the table beside at 400%.
Normal models should be pulled at 5G, very fast and strong models can be pulled at 10G.
If you have a normal model weighing 2,5 kg, than you will need 2,5 kg x 5 = 12,5 kg of pulling power.
BG 2,8 is the right rubber in this case.
Obviously you can take more than one rubber in parallel.