What size propeller for a 36 V DC motor?

["Followup-To:" header set to rec.models.rc.air.]
On 2010-07-29, John Doe wrote:
| "Morgans" jsmorgancharterJUNK.net wrote:
|
| Look in places that talk about remote control airplanes, because
| that is what even the man carrying experimental airplanes are
| borrowing knowledge from, on the subject of electric flight. It
| is just at larger scales.
|
| I believe that, but how come you never see a real airplane
| standing on its tail?

Because you don't look in the right places?

http://en.wikipedia.org/wiki/Lockheed_XFV
http://en.wikipedia.org/wiki/Convair_XFY

Ultimately, yes, for electric flight, most of the innovation is
happening with models and UAVs because that's where it's more
practical. Once you get into planes large enough to carry humans, the
cost difference between electric and internal combustion becomes huge.
For example, for a powered parachute, somebody mentioned a 30 hp
engine. You could have that engine for a few hundred dollars, perhaps
a thousand, but a comparable electric setup would cost way more, and
something that will keep you up for an hour or two will weigh way more
than the equivalent gasoline powered setup and cost even more.

Full scale electric planes do exist, and I would expect more work in
that area, but it's not going to really be practical for most uses
until battery or fuel cell technology gets a lot better (or at least
cheaper.)

And also, if your model fails, you've got a pile of sticks to fix up.
If your full scale plane fails, you might be dead.

But good ideas certainly do flow in both directions.

| Looks like that would be a neat way to
| simulate a Harrier landing, and takeoff.

Yes, though the examples I gave had massive problems. The first was
never even taken off vertically!

--
Doug McLaren,
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