Search results

The Rocketry Forum

Help Support The Rocketry Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
  1. A

    3D Printing of Hybrid Grains

    3D printing for structural integrity is...time consuming. For most hybrids 54mm and under, as long as you aren't running pure wax you'll get a curve that looks like TMT. It is hard not to. ABS, PVC, HDPE, Polypropylene, Santoprene, the list goes on and on and on. The regression rate of most...
  2. A

    RCS aerospike nozzles

    I have barely noticed any difference on the test stand between a convergent/divergent nozzle and an aerospike. They were similar and if I didn't know each thrust curve/pressure curve was, I wouldn't know which was which. I did 10 of each as a comparison in 2007. These hybrids had no metals and...
  3. A

    RCS aerospike nozzles

    This is an aerospike that I developed and tested a lot in a hybrid. https://alphahybrids.blogspot.com/2008/08/for-those-about-to-rock.html Edward
  4. A

    Hybrid Rocket Engine

    A lot of the combustion instability looks to come from the paraffin melting and being ejected through the nozzle. Try a grain where you use 50% paraffin, 50% melted hot glue sticks (high melt) Edward
  5. A

    Hybrids 2020

    https://www.catalinacylinders.com/markets/small-high-pressure-cylinders/ The 9001, 9002, and 9003 sizes are great for 54mm hybrids, as they are 2" OD. Edward
  6. A

    Hybrids 2020

    For pre-filled tanks I used the 9000 series from Catalina Cylinders. I had them oxygen cleaned. The 300cc cylinder could be filled to 204 grams. The 440cc cylinder could be filled to 300 grams. The 9000 series has three options that are 2" outside diameter. They also have a 150cc option (102...
  7. A

    Found Aerotech Hybrid or Alpha Hybrids system want to buy

    If you want to stay with a monotube style system but upgrade the injector to a showerhead system, I can share with you a U/C based system that I developed. It has been static tested up to O class motors. Still fills and fires through the mid-bulkhead. Edward
  8. A

    Found Aerotech Hybrid or Alpha Hybrids system want to buy

    Doug - I got your request. I'd be glad to help out your university team with some hardware. Edward
  9. A

    Hybrids 2020

    I have seen from 190-210 with wax and EVA. Some people think that there is this magic fuel combination for maximum ISP. There isn't. It is a system parameter that depends highly on the specific system. Oxidizer pressure and density, chamber pressure, injector, grain configuration, mdot Ox...
  10. A

    Hybrids 2020

    Regression rates can easily be adjusted by the HTPB/Powdered wax ratios. When the initial testing was done in 4-inch hardware they were able tailor that to the 5" motor. As I said, much easier than trying to heat wax, pour in, keep headed, centrifugal cast, etc. I've done a lot of centrifugal...
  11. A

    Hybrids 2020

    The fuel grain was 4.5" OD x 30" long. Average of 4mm/s. Some tests were up to 7mm/s. They had a long beautiful yellow flame with white exhaust (aluminum oxide). They used a 6 fin finocyl grain. Pre/post combustion chambers. Edward
  12. A

    Hybrids 2020

    Interesting - I've seen it, but didn't know that it was heavily favored. If you want the same performance, with much less work, mix powdered wax (choose your preferred type) with HTPB. The type of wax didn't have a noticable impact on impulse - it was just there as a hydrocarbon. I typically...
  13. A

    Hybrids 2020

    Thank you for this information - do you know how heavily this fuel and injector combination is favored? I've done *a lot* of HTPB and parrafin, but have never mixed them, does the HTPB cure? How do you control the cooling and size of the wax particles? Are the two fluids miscible? GOX is a...
  14. A

    Hybrids 2020

    I use a pintle for the tribrid. Fuel through the center and oxidizer along the outside. The ones I've tested with alcohol and nitrous the ISP is 205-220. In O-P size motors I have seen numbers from other groups in the same range. They typically try to run 4-6 O:F ratio. Like impinging pintle...
  15. A

    Hybrids 2020

    Disclaimer: Static tested over 2000 hybrids, from H to O sized. Definitely, you can have impinging injectors. One great thing about nitrous oxide is that it atomizes very, very easily because it flashes from liquid to gas in the chamber. I never saw that like-like impinging injectors were...
  16. A

    Hybrids 2020

    I have never done a test without a pre and post combustion chamber, so I don't have data to compare to. The longest burn motor I have tested is an N1000, 17 second burn. I used PVC pipe for the liner and fuel chamber. In this motor, the liner in the post combustion chamber only had about "0.050...
  17. A

    Hybrids 2020

    That is inline with what I have seen. I've been testing hybrids for 15+ years, and found that trying to upgrade the injectors has been an adventure in diminishing returns. Somehow performance increase is inverse to the amount of time it takes to machine the injector. :) I'll preface this by...
  18. A

    Hybrids 2020

    Awesome 4" motor - do you have a comparison on the performance increase due to the swirl injector? Edward
  19. A

    Parachute patterns

    Very nice calculator! All the pulled down apex and annular parachute I have made the gores end up with a coke bottle shape - is this true of the ones in your calculator? Edward
  20. A

    Blank Bullet Parachute Ejection

    I have used very custom blanks for steel cable cutters. They were center fire and worked very well. Edward
Back
Top