On Apr 14, 12:58*am, Jim Logajan wrote:
Le Chaud Lapin wrote:

Does anyone have any idea of the ratio between thrust power and churn
power?

There are literally hundreds of books on propellor efficiency - some
exceedingly inexpensive. There are probably dozens of web sites you would
find by a simple google search of "propeller efficiency". A newsgroup on
piloting is really the last place to ask - once one has done their own bit
of research and come up empty. What resources did you use that you couldn't
find an answer?

None. Didn't think to look, but it does indeed say 80% on the
Wikipedia page.

http://en.wikipedia.org/wiki/Propeller

(Anyway, try he

http://www.allstar.fiu.edu/AERO/BA-Background.htm
)

All repsonses gave very good suggestions. I was suprised that the
ebook that Tina linked to had such detailed theoretical information
about flying in 1920. I guess I have seen one too many videos of
"slapping pancake" contraptions.

Also, another reason for the laziness is that I am knee-deep in a
research project, so for weeks I have been trying to abstain from
thinking about flying, as I can only think about one hard subject at
once to be productive, but over past week it's been hard to resist.

As I am still learning to fly, I have come across many articles about
flying cars. Yes, I know, it's the honey-pot for crack-pots in
aviation, but it seems that there are a lot of people interested in
having such a contraption, and not just people like Moller.

So during my breaks at lunch, I have been thinking about flying
vehicles, what they might look like, given obvious constraints (should
not kill the children if prop accidentally starts), and so that's how
I started thinking about prop efficiency.

I also started thinking about balance, how there is not very much
variation on component distribution in GA aircraft. They all follow
the same basic model: wings are placed to counteract very heavy
components (engine) and cause turning. Elements on empannage used for
elevation and normalizing centripetal force toward center of
curvature. Yes, this is all obvious by opening any book on flying, but
when you start thinking about actually designing an aircraft, it
*really* becomes obvious. I am beginning to wonder if there are
alternative models that would reduce length of aircraft
significantly. The existing model is tried and true, but there is no
law that say that the component distribution must be as it is now.

I think though, to get away from tried-and-true, if there is any value
in doing so, would require the designer to acknowledge the great
benefit that computerized control would bring. And I don't mean
Stealth, which is an obvious example. It might happen that the so-
called flying car would be best served by breaking away from the
current model and going with something that is a bit more distributed,
with computers effect what the pilot implicitly specifies via fly-by-
wire controls.

Needless to say, this is an *extremely* exciting field. Wish I had
more time to think about these things.

-Le Chaud Lapin-