Small and Simple Hybrids are Possible

Tony Belding · 2004-06-06T02:02:11+00:00

I noticed a thread talking about how hybrid motors could be scaled up. . Nothing wrong with that, but I think the real challenge is to make efficient small hybrids and make them less expensive and easier to work with. The G and H region is what needs attention, in my view.There's a Yahoo group called "microhybrids" with info about motors using tiny, disposable, 8-gram cylinders (or bulbs) of nitrous oxide. If you've ever seen the little 8-gram bulbs of liquid CO2 used to charge up soda fountains, or the 12-gram bulbs used in airguns, you have the idea. It appears that the little nitrous bulbs are used in some manner to make whipped cream. When used in rockets, they produce about high-D to E power. (Here's the group, by the way: )There are some shortcomings. . . The bulbs are too tiny, we need something with more juice. The total impulse is right in the area where composite or even black powder motors are inexpensive and easily available, so some will ask what's the point? And the bulb requires a hardware mechanism to support it and hold it tightly sealed against the injector assembly, which increases the size and weight.If we could get a larger disposable cylinder manufactured with a threaded neck, it could solve a lot of problems. At least one company is already making such a cylinder filled with CO2, for use in air rifles or paintball guns: holds 88 grams of CO2. So if we had these filled with nitrous, that could put us up into the realm of H motors, at a rough guess. The threaded neck raises the prospect of a hybrid motor that you simply screw together and launch -- no need to transfer liquid nitrous between tanks.One other nice thing about disposable bulbs is, the walls don't have to be made extra thick to withstand multiple fill-and-empty cycles (and the resulting metal fatigue as years go by), so they can be lighter weight. They can also be filled more precisely at the factory than anybody fiddling with a set of scales at home could do, so...

Jun 06, 2004 104 Replies

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almax 22 years ago

It chips like a bird at the end !

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Len Bryan 22 years ago

That is very cool!

I would buy one. Please keep me posted.

Len Bryan CAR S620 L3

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Marcus Leech 22 years ago

Is it machined ABS for fuel, or an ABS pipe? The smallest ABS pipe that I was able to find was 1-1/4" DWV, which at 1.660" OD, is clearly too large for a 29mm motor :-)

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Todd Moore 22 years ago

It's 1"OD Black ABS Rod. I drilled the port on the lathe, but the OD is a perfect fit for a .058" wall 1-1/8" aluminum tube.

Todd

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Marcus Leech 22 years ago

Ah. I was thinking 1.125" x 0.065" wall tubing, which would require (slight, admittedly) OD machining of 1" bar stock. Among the machinable plastics available as bar stock, ABS is right up there with Delrin and Nylon in expensive. Leveraging the *massive* plastic pipe market works once you get into 1-1/4" SCH 40 and above...

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