Scratch Why Not? Original Design / Scratch Built

Scratch - Why Not? {Scratch}

Contributed by John Chapman

Manufacturer: Scratch
(by John Chapman - 08/24/05) Why Not

Brief:
This is an 18mm engine altitude rocket with "Hillary Duff" graphics, built with my daughter to interest her in rocketry.

Construction:
The BT50 based design has elliptical fins for efficiency, giving good altitude for schoolyard launches on smaller engines. Its light construction gives good parachute duration. Finally, the hot pink color and Hillary Duff graphics delighted my daughter.

I started by sitting down with my daughter in front of the PC, with Rocsim running. We selected body tube and fin style. The velocity is relatively low, so we did not need TTW construction. We started by assembling an Estes engine mount, rocsimming fins and printing out the template. We then cut out the fins, sanding on the airfoil after gang-sanding them to identical dimensions on a belt sander.

We used 100 lb Kevlar® thread fastened to the engine mount for parachute retention, with a short length of elastic for give. The parachute is attached to the stock plastic Estes nose cone with a ball-bearing fishing swivel. Voila - no tangled shroud lines!

For the graphics, we got photos of her favorite singer, Hillary Duff, from an online source. We printed these onto plain paper with the printer after appropriately sizing them for the fins. We got the name from one of Ms. duff's songs. We used the same "plain-paper printing" technique to create the logo and name on the side.

We used Wal-Mart fluorescent Krylon paint to get the hot pink color. We used CA to attach the graphics, and then clear-coated over the rocket in several light coats. It really shines.

We now call these "girl rockets".

Flight:
We have flown this twice, once on a B 6-4, and once on an A 8-3. Both produce ejection that is just about optimal. the rocket is not overstable, so it doesn't weathercock. The small engines allow one to appreciate just how far tis coasts after the engine ceases boosting. the stock 12" parachute takes this a long way in a breeze, but drops the rocket softly almost onto our heads in calm conditions.

We use crepe paper for wadding, with a fold around the rolled parachute for protection. this works perfectly. No singeing of chute. The rocket looks new after two flights, thanks to a combination of correct engines, good chute and little wind.

The hot pink color makes the rocket VERY easy to see against the sky. I believe I'll build several more "girl rockets", for just this reason.

Summary:
Pros: GREAT way to get girls into rocketry. Hot pink looks unusual, but is VERY practical for finding rockets.

Cons: Not for those insecure in their masculinity. It is the antithesis of "macho". The graphics would be better on decals.

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