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Just keep in mind that GOX, O2 etc have more critical regression rates than monopropellants such as N2O and H2O2. You can be off by quite a bit with these latter two and still get decent behavior and performance. For the former you want to be pretty close. CO2 is an example of an oxidizer with...

If you are going to be at the upcoming big Potter launch, look me up. I'll be bringing THRP-1 to fly. Gerald

The inside layer on those is a type of glue stick. It's purpose is to glue seal and provide strain relief. It doesn't like a lot of heat since the glue reliquifies readily enough. But it can be quite useful in some situations. I've used a lot of it. Gerald

Hmmm, wig fins!

Take a scrap of the heat shrink, shrink it, and measure the shrinkage. Odds are your tube absorbed some epoxy, pulling the surface down. There is also shrinkage when epoxy cures. It is not much, and occurs mostly near the end of the cure. So it pulls in slightly towards the tube anywhere it...

Also using a pump to run air through can also deposit an oil film from the pump.

Acetone is NOT the last step in prepping tanks for oxidizer service. Acetone is a fuel and can leave oily residue. I'd suggest following the acetone with denatured alcohol, and ideally following that with hydrogen peroxide of successively increasing percentages. That takes care of any remaining...

Thanks for the link to the tape. I hadn't run across it before. Ordered some... TS-4 in small quantities (2 oz) seems harder to find! Gerald

Just a warning - Ken will talk your ear off! Gerald

Does anybody on your team have either a Tripoli or NRA certification? And what goes along with it, experience working with commercial solid propellant motors? Also, does anybody on your team have experience working with KNSB in smaller motors, at least up to size M? Or at least APCP EX motors of...

https://www.fibreglast.com/category/Surfacing_Veils for those who are interested. Gerald

Fiberglassing is usually done nowdays with laminating resin - an epoxy. Epoxy doesn't stick to nylon. I doubt epoxy sticks to silk either. I'd use something else. There are non-woven fabrics made for this purpose. Don't expect them to impart any real strength though, and they are a bit of a...

Would like to see something that says "excellent, no swelling" sometime! It would become a candidate for a composite flight tank liner coating. With the swelling that does occur, I wonder if we should resize our O-ring grooves in the axial direction to allow for a bit of expansion without...

I figure it is a bit of a square/cube problem. For large motors, the nitrous mass vs grease mass ratio is quite high. For tiny motors, the ratio is not as high. The impinging temp would have been, what, somewhere around -160F? That would seriously decrease solvent action, by orders of...

I read too quickly. I saw the PTFE in the first listing, missed the PFPE. Regardless I don't trust drawer grease to not have other things in it that could make nitrous more easily go boom. Anyway the second listing I like a whole lot better. It mentions the appropriate compatibility, and price...

Pure teflon would be a solid. The question is what is the carrier? Will it sensitize N2O? Krytox uses a fluorinated hydrocarbon if I recall correctly... Fluorine doesn't let go of things easily! Teflon is fluorinated, but without info on the carrier I wouldn't use it. First thing to check for...

I don't recall offhand which O-rings are in my flight tank at the moment. https://www.marcorubber.com/o-ring-chemical-compatibility-chart.htm#chemId=1483 Check other sources as well. This was just at the top of the list of a quick google search. Keep in mind you also want your o-ring to be...

Teflon can act as a high temperature oxidizer. Gerald

RTV silicone or other coatings with or without solvents - look up the chemical compatibility of the material before doing it. You may inadvertently change the load and/or the shock rating by a lot and not realize it. RTV silicone depending on type emits acetic acid. BTW, with Kevlar you want...

If you have a really fat rocket and a little motor, it will probably reduce drag. That is, the exhaust plume is way too small for the rocket diameter. But in that case, who cares? It's not a performance rocket. Easier to get rid of the fat or put a bigger motor in. Or just add an appropriate...