× We have recently moved to a new server. If you run into any issues, please let us know through the Contact Us link at the bottom of the page. Thanks for visiting RocketReviews.

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.

comment Post a Comment