Re: Indoor Props - Pitch versus Ceiling Height

From: Peter L. Hess <hesspl_at_comcast.net>
Date: Mon, 16 Apr 2007 15:40:36 -0000

Bill:

Thank you for taking the time to share your thoughts on this
subject. While others might have different opinions, I highly doubt
that what you say will be considered "rubbish" by anyone.

I am particularly intrigued by your suggestion that having the prop
stall at high torque would be helpful. While I have always thought
that having the prop stall was something to be avoided my initial
untutored response to your suggestion is something like, "Why, of
course, so long as the prop continues to generate enough thrust to
keep the plane in the air and so long as the prop returns to an
unstalled condition by, at the latest, the time the plane enters into
the cruise portion of the flight."

Also, your suggestion that going to as low as 20" pitch might be too
far or that any lower pitch might not be helpful is certainly food
for thought.

In any event, it is definitely high time for some more prop building
and experimentation. Now that the flying season in Glastonbury is
ended, if only I did not have to drive a couple of hundred of miles
to conduct those experiments.

Thanks again for your thoughts.

Peter Hess
Canton, CT


--- In Indoor_Construction_at_yahoogroups.com, "Bill Gowen"
<b.gowen_at_...> wrote:
>
> Peter
> I haven't achieved an ideal prop for Cat 1 so far but my props are
working well for Cat 2. I'm not convinced that an extremely low pitch
is the way to go. I think that given a flaring blade or spar (your
choice here - I go for the spar) the more pitch you start with the
more pitch change you will get. Maybe my aero mentor Mr. Barker will
correct me here but this just seems like a logical assumption. This
could well be the cause of your problem in finding the "magic
solution". As far as stalling the prop goes I think that would be an
excellent outcome. The solution would be to add more torque until the
stalled prop is pulling the model enough to stay airborne. I believe
this is what happens with VP's in low ceilings. I would also consider
an unbalanced pitch condition at the beginning of the flight to be
beneficial as long as you can keep the model flying.
>
> This may all be rubbish - just describes what I'm trying to achieve.
>
>
>
Received on Mon Apr 16 2007 - 08:41:38 CEST