|4.16x Up-Scale of the classic Estes kit|
My current Andromeda Collection:
|Weight (Dry): 15.519 lbs|
|Length: 177" (14' 9")|
|Fin Span: 4' 1.5"|
|Motor Mount: 38mm|
|Recovery: 96" Parachute|
|4" Tubes: LOC Kraft|
|3" Tubes: PML Phenolic|
|"Conduit Dowels": 74" 1/2" Oak Dowels|
|"Conduit Stand-Offs": 3/8" 7 ply bud Nosen|
Main Fins: 1/2" 12 ply
"Ram Tube" fins: 3/8" 7 ply Bud Nosen
|Ram Tubes: 4" LOC Kraft|
|Small outboard fins: 1/4" 5 ply Bud Nosen|
Photos By Dan Michael
|A great Video on a J570 (2.3 Megs)|
Why would I do this?
I built my first Andromeda in 1975, when I was 10 years old. The price was a whopping $4.95, a months worth of allowance. I remember finding recyclable bottles and turning them in for 2 cents each and saving my allowance. I was the envy of the neighborhood. I think I got two flights out of her, when the chute failed to deploy and she lawn darted. I remember building at least three or four more of them in the years to come. I had several rockets, but the Andromeda was always my favorite. Most of the time she was the only rocket I would even take with me to launch. I think it was the slow, "majestic" lift offs and the fantasy of pretending I was the captain, traveling to Jupiter. I knew all of the fantasy details described in the instruction sheet. "The 30 man exploration vehicle was built in earths orbit. She is over 2000 feet long and the sails are 600 feet wide. Propulsion is a center hybrid rocket engine and two outboard nuclear ram-type engines." Boy, to be a kid again... Thanks Vern Estes.
My father would pick me up on Sundays and, during the summer, we would sometimes build and launch rockets. The Andromeda was his favorite too. He passed away when I was 15, in 1981, and that summer we built and flew our last Andromeda together. I didn't launch rockets again until I was 22.
I didn't do a very good job documenting the construction. I didn't think of it until I was deep into the project, sorry. I downloaded the original plans from Jim Z. There was a problem with the scale when designing the parts. The 4" tubing scaled out to 4.16x while the 3" tubing scaled to 4.10x. Most of the rocket was designed using the 4.16x scale. Some of the parts had to be 4.10x while I compromised in some places using 4.13x. This kept the whole package as proportionally close to the original as possible.
I waited until the last possible moment to chose the motor size. I even painted most of it before choosing. The reason for this was weight. I wanted to know the exact weight of the finished rocket. The large fins will experience a great deal of torque during the initial thrust. I wanted to choose a motor that would have enough power for a safe flight but not so much that the g force would tare it apart. Each step of the way, my thoughts were to keep it as light as possible without sacrificing strength.
It was a challenge making the main fins. Ellipses can be hard to upscale without plugging in multiple coordinates into a CAD program. The guys in the engineering department have been busy so I opted for an easier way out. I printed the plans from Jim Z onto clear overhead projector paper. I measured the root of the fin and placed that dimension on a piece of drafting paper. I then projected the image onto the drafting paper so that it lined up with the upscale dimension on the paper. The projector was squared and leveled several times. I then simply traced the projected image onto the paper, cut it out and traced it onto the wood.
The three rings on the fin can act like exterior centering rings. Counting these, the main fins are mortised with 7 centering rings. The 3" tube goes all the way to the bottom so there is only 1/2" of fin "through the wall". I tried to compensate by ID fillets & epoxy rivets. The entire ID of the 4" tube is coated with epoxy and the CR/fin joints have1/4" of epoxy poured on them, all sides. All epoxy between the 4" and 3" tubes are 2 hour slow cure. In all, the fins are attached with 9 oz of 2 hour epoxy. Another bit of security was several (probably 30 or 40 in each fin) 1/4" deep 1/16 holes were drilled into the fin roots to act as epoxy rivets.
The small outboard fins are attached with four 2 1/2" long 1/8" diameter oak pins. Each pin goes through the main fin and into each fin 1". 2 hour epoxy here too. Again, another bit of security was several 1/8" deep 1/16 holes were drilled into the fin roots to act as epoxy rivets.
The conduit dowels were secured to the main fins with a kind of mortise and tennon thing. The depth of the mortise is about 1 /1/2".
Finishing the rocket was one of the more difficult tasks. The majority of the "decals" were made form Super Monokote. Jim Z made some upscale "paint masks" for me. At first, I tried the rubber cement/paint mask thing. What a disaster! The paint bled like a stuck pig. So I 86'd the paint mask idea and cut out the decals with orange Monokote underneath. The white was done the same way but I used sticker material. The paint was Rustoleum satin black.
The three "cooling rings" were painted white in the '75 & '76 Estes catalogue. They were painted black in the '77 through '82 catalogues. I opted to paint them white to add contrast in the area.
I just had to throw this in for good measure: Not counting any internal fillets, the total length of the fillets on this puppy is 41.6 feet.
First flight was on April 20, 2002 on a J350. The chutes tangled and it had a hard landing. I am in the process of rebuilding it right now and should have it ready to fly again at the May 11 2002 NEPRA launch.
The second flight was at the May 11 2002 NEPRA launch on a J570m. The delay was a little long and the chute tangled some but only suffered minor damage.
The third flight was on August 17th 2002 on a J570 with a SHORT delay, at the NEPRA launch. A perfect flight with absolutely no major damage.
This rocket has flown many more times. The only motor I use is the AT J570s. Each flight has been perfect.
Special Thanks go to:
Jim at Jim Z Rocket Plans for making the paint masks.
Many of the components were bought from Giant Leap Rocketry and Magnum.
Back to The Drake Bucket 'O' Photons Telescope Trailer HAL 9000
HPR Strength of Materials Who The Hell Is The Drake Rocket Pics