Charles J Knight wrote:
>
> > * They are loud as hell. Even muffled, they are generally WAY louder
> > than you'd think they could possibly be. Running one indoors on a
> > test
> > bench is painful without ear protection.
>
> I wonder if active noise cancellation could produce a "better
> muffler?"
>
> Andrea produces a microphone headset that has this built in --
> it actively produces a cancelling wave that produces clearer,
> "quieter" recordings.
>
> Since there are no big "bulges" on the ear mounted headset,
> I'm guessing it's a simple circuit, perhaps including an LSI
> chip.
>
> Same technology, installed in a box, could "eliminate" a lot
> of the noise. Hmmm...wonder how quiet we could make one
> of these things?
Interesting idea... you'd have to enclose the motor in some kind of
noise-proof box, though, since the noise produced by these things is
very non-local. It just kinda comes out of the whole motor. In any case,
they're certainly not too loud to use for an outdoor-type application,
but I suspect that running one indoors would be not worth the trouble.
Not to mention fumes, of course.
>
> > * They burn gas relatively fast. They're not very efficient at all,
>
> That surprises me... Usually diesels are relatively efficient,
> if designed right.
These aren't designed right. :-) Really, they're designed for short
flights in close proximity to maintenance. The one I had used a roughly
one pint fuel tank, on which it could run for maybe a couple hours,
continuously. I guess in some applications, that would be fuel-efficient
enough, but in terms of efficiency, I think a lot of the fuel gets
sprayed straight out as exhaust.
> > There are some restrictions on what you can use as fuel, and IIRC it
> > produces some fairly foul exhaust. Running indoors is not
> > recommended.
>
> What kinds of restrictions? Legal?
>
That wasn't very clear, was it? By restictions I meant in terms of
combustibility and reactivity with the glow plug. I've avoided chemistry
like the plague, so I have no idea what class of fuel would properly
react with the platinum glow plug and allow the thing to run. But I'd
imagine any potential fuel would need to be both highly combustible
(that glow plug doesn't generate all that much ignition energy), and
react properly with platinum. It wouldn't actually have to burn all that
clean. These motors are pretty simple, and can take a lot of beating on,
crud buildup, etc.
On another note, the horsepower specs posted in another message were
very interesting. One of these motors could easily provide enough power
to quick-charge my cell phone in about 2 hours (it'll run for ~four days
on a charge). For a source of energy to charge wearable batteries in the
field, this actually seems like it might be a pretty good choice.
--Rusty
--
"You can never entirely stop being what you
once were. That's why it's important to be
the right person today, and not put it off
until tomorrow."
--Larry Wall
http://www.ompages.com: Freedom Now.
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