18 years ago
. 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:
That 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
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 you *don't*
need to leave as much empty space in the bottle as a safety factor
against over-filling it. That should allow them to be somewhat more
size and weight efficient than current hybrid designs.