Project
410 Flight

Post-flight Analysis

• This rocket would have been a success had the rocket body not failed structurally. There was a 12" section of tube the engines fired through. This section was coated with two coats of epoxy to give it's surface strength and prevent the cardboard from being eroded by the hot exhaust gasses. Even with the epoxy, the rocket body was shredded almost immediately.
• All of the seven engines fired perfectly as did the ejection charge.
• Seven J300 engines produced 8400 Ns of total impulse with a peak thrust of 840 lbs. The total take-off weight was 56.5 lbs.
• The nosecone was filled with fuel and allowed to burn uninhibited to act as a smoke tracer. I'm sure this wasn't the best idea and might have contributed to the failure. Future designs will not have this type of smoke element.

Construction

• A cardboard concrete tube was used as the body. It's low cost and light weight made it ideal.
• Bulkheads were made out of 1/2" birch ply which were connected to each other with 1/4-20 aluminum threaded rod. 3/4" pine stringers were attached perpendicular to each bulkhead to provide a surface to attach the rocket body to.
• The pine stringers were used to structurally enhance the engine section of the rocket by bolting the fins through the cardboard and wood, sandwiching them together.

Pros

• All of the igniters and engines worked perfectly. The J300 engine now has a 13 out of 13 success rate.
• Chemical time delay element and ejection charge worked perfectly as evident as a "pop" in the video. Unfortunately, the rocket body had structurally failed by that time.
• New 20' launch rail is easy to transport and erect and will work well on subsequent rockets.
• Entire rocket cost under $100
• This cluster design has potential to lift a video payload in the future.

Cons

• The structure of the rocket vehicle needs work. This is a lot more difficult than developing the engines in that the engines could be static tested but a launch vehicle has to be launched which might mean a lot of good engines and time will go into a bad rocket.

Pictures

Video

• Flight 01

Drawings

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