Scratch Mark III Original Design / Scratch Built

Scratch - Mark III {Scratch}

Contributed by Darren Longhorn

Manufacturer: Scratch
Mark III
(Contributed - by Darren Longhorn)

MkIII on the padI thought I had made a mistake with this one, I could never add enough nose weight to make it stable during a spin test. I was trying to make a really small diameter tube, by wrapping paper around a wooden spoon handle. There wasn't going to be a recovery system, the engine was going to eject, and the rocket would tumble back. Since then I've learned a lot more about stability. I learned about the CP ( centre of pressure) on rec.model.rockets ( a great news group to subscribe to if you're interested in this stuff), and where it should be in relation to the CG ( centre of gravity).MkIII the end

So anyway I entered the MkIII design into VCP, wRASP & RockSim, and it came out stable, so I flew it. Actually it flew well, really high and the engine ejected too. It just didn't go unstable and tumble, so it lawn darted. The body tube is a bit bent now, and due to the construction is probably not repairable, so retirement beckons.

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