Wednesday, March 19, 2014

Behold the Scratch Built Rocket

It has been almost twenty years since I built a model rocket like this one. There are no commercial model rocket parts in its creation. In fact, you can call this a "craft store rocket". 
Really, it isn't much to look at. It's downright homely. The body tube, rolled from poster board and using a technique derived from the work of James Yawn  is just 5.5" (140 mm)long, 3/4" (18 mm) internal diameter, and just a shade under 1" (24 mm) outside diameter. It is not perfectly circular; instead of using spray adhesive, I used thinned wood glue, which was not spread as smoothly as it could have been. On the inside is an engine block, made from a strip of 1/8" (3 mm) poster board that was wrapped around the nearest thing I could find that was close to 1/2" (12.7 mm) in diameter; a AA battery. This was wrapped around until it matched the internal diameter of the body tube, and then glued about 2 3/8" (60 mm) from the bottom of the body tube. 
The nose cone is built from a core that used one of those 2 3/8" (60 mm) wooden peg men or game pieces. I built a washer that brought it up to the same diameter as the outside of the body tube, and used a card stock shroud to give it that nice conical shape up to the "head". 
Still need to smooth that part out.
The three fins are perhaps a bit too thin, using 1/16" (1.6 mm) balsa I had on hand. Their design is as old as model rocketry itself, reminiscent of the fins found on such classic birds as the Estes Big Bertha, or perhaps more appropriately, the Model Missiles Inc. Rock-A-Chute Mark II, the first true commercial model rocket. Their design is almost fool proof. Its sweep and area insures that most of the center of pressure is a bit further back on the model, but on this rocket, with that very heavy nose, this probably was not necessary. 
For a launch lug, I used a bright green Post-It note I had on hand, wrapped around a 1/8" (3 mm) dowel. 
There's still work to be done. Obviously, it needs to be finished. I have the screw eyes to attach the recovery system, but I am still not sure what to use (leaning towards streamer). 
The finished rocket stands around 9" (225 mm) tall. 
It is, however, 100% mine.
My first attempt at scratch building a rocket goes all the way back to kindergarten, but that wasn't a flyer. My fellow students and I were each given one green, one yellow, and one red piece of construction paper, and then we a pattern to make the nose. The rest was much simpler. I figured out the cone very quickly. My rocket had a green tube, yellow nose, and red fins. 
It was my first "model rocket".
It was in the spring of 1975 that I made my first scratch built model rocket for flying, and it was horrible. None of the rockets I owned at that time were usable, and some of the neighborhood kids were launching at Brookview Field, just behind our house. I had an engine, an Estes 1/2A6-2 (which were leftover from a pack I bought to launch my friend Craig's Estes Astron X-Ray; by the way, that is the absolute wrong choice for that rocket). I decided to throw together a rocket from what was on hand, and that meant a toilet paper tube, some cardboard, and a makeshift streamer from crepe paper. 
It went together in about thirty minutes. 
And never flew. 
By the time I got out there, they were packing their things away. 
The groups de facto leader, though, decided to humor this strange little twelve year old broke out his launch pad. I had my the rocket ready to go, with my one igniter. 
A word about those old igniters.
Before the newer low current igniters ("Solar Igniters", now known, inexplicably, as "Starters"), there were older designs that were nothing more than nichrome wire with a length of flammable material painted on them near their centers. These igniters required a lot of current to work, at a minimum 6V supplied in the form of six D sized batteries.
His was a motorcycle battery.
As luck would have it, his battery was exhausted. 
When we tried to launch my rocket, the igniter failed.
So, I thanked him for the effort, removed the engine, tossed the rocket in a waste barrel next to the baseball diamond, and headed home.
This still unnamed rocket is the spiritual heir of that rocket. Like that one, it has been thrown together with material that was either on hand or easy to get. And like that rocket it was thrown together because I am suffering from a colossal case of "rocket fever". 
Years have taught me, though.
In a few days, it will be finished, receive a paint job, hopefully taste the air at speed.
Well, that's the plan at any rate.

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