Project
413 Flights - IE24E engine test
Results
- Besides the first day I launched a rocket, Flight 01, this was by far the most rewarding launch day I've ever had. Eight out of eight engines worked flawlessly. Six of the engines were flight tested and two were static tested. The main focus of these tests was to evaluate revision E of the IE24 engine. Of course there were other problems, the cylindrical fins were heated by the hot exhaust gas and melted off the rocket halfway in flight causing instability. The first static test had a 2" PVC cap on the end of the engine which was pushing on a hydraulic cylinder. Halfway through the test the cylinder broke through the PVC cap producing erratic thrust data. See video. After the first static test the pressure gauge was stuck on 140 lbs. and would not zero out so the second static engine was just launched. Even with all these problems, the main objective of the 413 engine tests, to produce a stable engine, was an overwhelming success. I think I finally have an easy to produce, low cost power plant that can now be used on larger projects.
Construction
- Engines were made from 2" Sch. 40 PVC 24" long. See IE24 engine construction instructions when completed. Engine nozzles were cast in the engine casing and restrained by four 1/4-20 x 1/2" steel bolts. The engine end cap was made with silicone and Pourstone, silicone sealing between the Pourstone and the casing wall. A 1 1/4" PVC end cap was inverted and put on top of the Pourstone, then restrained with four 1/4-20 x 1/2" steel bolts. Four 3/16" aluminum rods 18" long were used to hold the cylindrical fin section aft of the engine nozzle. 4-14 aluminum lugs were used to connect both ends of the rods with the engine and fin section. The fin section was made of 6" sections of 2" sch. 40 PVC. There was a 2" section of fuel used as tracer smoke and a 1/2" PVC union with .003" brass shim stock acted as an ejection charge.
Pros
- Total rocket weight was 8.76 lbs.
- Center of pressure was 12.4" from engine base.
- Center of gravity was 13.5" from engine base.
- Stability was .46 caliber.
- Engines were extremely easy to construct.
- Engines cost less than $3 each.
- Rockets cost less than $10 each.
- Engines proved reliable for larger projects.
- Silicone prevented end caps from leaking.
- There was nominal erosion in the nozzle throat.
- Launch rail guides worked well.
- Nozzle retaining bolts worked well.
Cons
- Fin rods heated and melted the PVC holding them in halfway through flight causing instability.
- Cylindrical fin design adds allot of drag.
- Recovery needs work.
- A new ignition system is needed. The car battery melted the micro switch used in the pressure switch making it useless.
Pictures
Video
CAD Drawings
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