- Joined
- Dec 29, 2011
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Where did you find your polyethylene powder? Mostly what I've seen is either quite high prices or quite large quantities.
Gerald
Gerald
Also can someone with a Skyripper54 motor measure the nozzle throat for me? I have misplaced that nozzle and need to make another one.
I can measure my 54mm SRS tomorrow. I would fill the central port of the pyrodex pellet with silicone. It will make them burn much longer.
Edward
I have one also. It is in new unused condition. I can check it this evening when I get home from work.
The nozzle with my 54mm hardware reads .563 in the throat.
Mine measured 9/16 (.5625) at the throat.
Edward
I'm ending up using bolts for pins in this hybrid. Not really my first choice but probably necessary given how I designed it. I have lots of bolts on hand, and nothing appropriate. Figures. So last night I ordered the bolts and a good tap as my taps in that thread were worn. Dull taps don't work well with aluminum. I'll likely be milling, drilling, and tapping this weekend.
Heck, I might even cast the first fuel grain this weekend. I'm ready to do that now and it is a much quicker job than APCP. I'm not doing anything fancy with the grain for the first burn. Not even any casting tube, just bonded straight into the liner.
I'll try to get some pictures sometime soon. It's starting to look pretty cool.
For those who have done EX hybrids - anodizing of any importance, or just skip it?
Gerald
John - I worked with a college group competing in ESRA this past year and they built a very nice hybrid. They did 3-inch subscale tests of many grains/fuels. They did do one of something very similar to the wax/wagon wheel grain. They found that they could get better performance from plain HTPB with 50% powdered wax in a finocyl shape. For the finocyl they used foam and melted it out with acetone after. I kept trying to convince them to do HTPB, Teflon and Magnesium.
Edward
I think that a simple geometry is much easier to control than having multiple types and bands of fuels. I've tried wax on the inside and HTPB on the outside. For the sizes we fly, I couldn't tell a performance difference. The college group did notice a big difference going from a single circular port to a finocyl port. I think that the regression rate would matter more when action time increases.
Edward
This is all the I250 hardware. There is only one reload certified for the I250 and it looks a lot like the HTPB/Wax reload.
I rarely fly certified reloads, even my own. All of these are of research tests and flights.
Edward
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