hybrid rocket

[jack_h]

can anyone tell my the presures involved with a nox and parafin hybrid rocket.

[Ray]

vapor pressure is dependent on temp, but keep it below 950 PSI...chamber pressure will (should) 150psi or so lower. Design your injectors to have that much pressure drop.

Typical stuff that I've seen is a bottle pressure around 750psi with chamber pressures around 600 psi at the beginning, falling to 400psi at the end. The containment for the NOX cools a lot during the burn, high flow rates, expanding gasses cause things to cool about 100degrees or so...

Unless you design the containment to be heated you'll have a regressive thrust profile...

Of note, NOX hybrids are one of the safest rocket motors you can build...they are usually self quenching when a nozzle gets plugged, however, NOX CAN go monopropellent.

You'll want to use hurricane wax, its harder and has a higher melting temp, so it'll stay in the chamber better. Add a little lamp black to keep only the surface melting, if you don't add it, the whole grain will heat and melt all at once...

[bob000555]

i dont know but if u dont put in a good valve when the pursure in the NOX tank gets low the flam can be "sucked back" into the tank and cause an explosion...

[Zippiot]

Wax works fine but the new "choice" propellant seems to be roofing tar. Lights much more easily and gives off suprizingly litte fumes.

If you really want to shoot for the moon, melt styrofoam into gasoline, take out the finished product and shape it, let dry for a few days. Should be rock hard but flexible, wicked nasty stuff but once most of the gas has lifted off it is quite a propellant. Gives off a few biproducts in the exhaust, mostly black gunk but not enough to chock a midsized nozzle.