HyperTECH Hybrid Question: Why both GOX and NOX?

The Rocketry Forum

Help Support The Rocketry Forum:


Sep 19, 2016
Reaction score
I've been reading about hybrids and the general theme is liquid oxidizer and solid fuel. NOX,LOX,GOX and HTPB, ABS, PVC, etc.
While reading HyperTECH's manual (https://www.hypertekhybrids.com/manual.pdf) they say they use both GOX AND NOX, and a solid grain.

Why do they use both Gox and Nox? Is it for boosted performance? Is this considered a Tribrid?

What makes it even more confusing is that in their intro, they never even mention the GOX.
"HyperTEK® hybrid motors are a “classic” hybrid configuration using a liquidoxidizer (nitrous oxide) and a solid fuel (a thermoplastic polymer). The nitrousoxide is a self-pressurizing condensed gas, which is stored within the oxidizertank. The behavior and handling of nitrous oxide is very similar to carbon dioxide.Under normal atmospheric conditions, the nitrous oxide is self-pressurized tobetween 650 and 750 pounds per square inch (psi), which allows the motor to operate at initial chamber pressures of up toabout 550 psi. As liquid nitrous oxide is delivered during motor burn (liquid phase), the tank temperature drops due toevaporative cooling, and the chamber pressure drops correspondingly giving the motor a regressive thrust profile, which isideal for nearly all applications. Once the liquid nitrous oxide is depleted, the remaining pressurized gas is delivered to thecombustion chamber as the motor burns for another few seconds at a reduced thrust level (blow-down phase)."

Here is one mention of GOX

"When the oxidizer tank is filled and the venting nitrous oxide is visible, the rocket is ready to fire. The rotary switch on thelaunch controller is placed on the “Fire” position, the countdown may commence, and at ZERO the activation toggle switch ispushed and held. When the fire sequence is initiated, the following events occur:· The ignition module and the oxygen solenoid are simultaneously activated. High voltage from the ignition module createsan arc across the exposed ends of the ignition wire.· A few milliseconds later the oxygen reaches the combustion chamber, and in the presence of the oxygen, the insulationon the wire begins to burns rapidly, igniting the fuel grain.· The fuel grain begins burning with the GOX, burning through the tie-strap that retains the fill stem in the Kline valve.· The tie-strap releases the fill stem, which pops free of the Kline valve releasing the flow of nitrous oxide into thecombustion chamber, and the rocket launches immediately."


Well-Known Member
Jan 19, 2009
Reaction score
They use the O2 to get things started up. It's a bit like the ignitor and preheater in a monotube hybrid like Contrail or Skyripper.


Well-Known Member
Mar 18, 2009
Reaction score
First, the system was developed to be regulation free. So, oxygen is not apcp or black powder. Put that filter on and it should make sense.

Next, an oxygen rich environment ignites easily.

A con is that if things do not go quite right I have heard of stems being melted.
Last edited:


Well-Known Member
May 4, 2010
Reaction score
A little more on the pros and cons of GOX vs preheater grain.
Gox is regulation free and also known as "pyro-free"
GOX does not require an igniter.
pyrodex is easy to obtain in most states and is used by Contrail
Rattworks uses a piece of solid propellant.
A GOX system requires more GSE
The U/C (Urbanski Colburn) valve is a simple system and reliable
GOX can be used to start a U/C valve motor commonly known as monotubes.
West Coast Hybrids used either or GOX or preheater.

I recommend starting with a pyro preheater for simplicity


Well-Known Member
TRF Supporter
Jan 18, 2009
Reaction score
Toney, AL
Too bad West Coast Hybrids are not still around, they were just starting to get their 76mm motors out there prior to the market taking a big dump...