Bill, how about a tutorial on sleeves ? What material, how long,
placement, etc
LeRoy Cordes
Chicago, Illinois
AMA 16974
In God We Trust
On Wed, 24 Mar 2010 23:55:03 -0400 "Bill Gowen" <wdgowen_at_gmail.com>
writes:
Re: sleeves
In a contest where you get 5 tries and there are usually time restraints
a fouled prop can ruin your chances. A record trial is a different animal
from a contest. At a record trial if your prop locks up while the model
is 75' up you can always (maybe) put up another flight.
Whether you use sleeves or not is a matter of choice. For me I would
never try to run a 24" motor on an LPP without sleeves. I sometimes use
sleeves in Cat 1.
----- Original Message -----
From: ykleetx
To: Indoor_Construction_at_yahoogroups.com
Sent: Wednesday, March 24, 2010 7:48 PM
Subject: [Indoor_Construction] Re: Hints for Cat IV LPP flying
I welcome all of your comments.
I was probably unclear in my previous postings. I didn't mean to say
that the partial motor method is flawed. Rather, that I implemented it
incorrectly.
In the 1/6 partial motor experiment where I used a 0.5g motor and a dummy
motor that weighed 2.5g, I was able to consistently achieve 25' of climb
and a duration of 2:50, with a max of 3:02. But I implemented this
method incorrectly because my dummy motor was too short. With a full
hook to hook distance of about 9", a 1/6 motor correctly applied should
be used with a dummy motor of 7.5". The 1/6 motor, about 4" long when
unwound, should be attached with a hook to hook distance of 1.5". In my
first experiments, I used a dummy motor of 6" long, so that the 1/6 motor
was attached with a hook to hook distance of 3.0". In these first
experiments, the results were good.
In the second experiments, I used the correct dummy motor length of 7.5".
The wound motor when attached was only 1.5" long. But in this new
experiment, the plane climbed less than 20' with a duration of about
2:30. The initial unwind seemed weak, the climb was weaker than before,
and the flights ended with lots of turns left.
(I also tried the full 3.0g motor to observe the full winding and
unwinding. I noticed the lack of tail hook clearance, which I changed.
I noticed that the initial unwind seemed weak as well. The behavior
seemed consistent with my second experiments where I applied the partial
motor method correctly. I did not fly with the full 3.0g motor to avoid
damage in the ceiling.)
I did not use a sleeve. I know that it's possible for the rubber to get
caught between the prop hook and the MS, but I did not see it in the 4 or
5 times that I unwound the motor.
--- In Indoor_Construction_at_yahoogroups.com, "Bill Gowen" <wdgowen_at_...>
wrote:
>
> Sorry if this has already been discussed but are you using sleeves?
>
> As far as a full motor having less power - how did you determine that?
Are you taking torque readings while unwinding the motor? It doesn't make
sense that a full motor would have less initial power than a partial
motor unless knots are dragging somewhere. A full motor wound to the same
maximum torque and backed off to the same launch torque should deliver
the same launch torque (power in your terms) as the partial motor but
more importantly it should do it for much longer. For example the number
of unwinding turns from .7 in-oz to .5 in-oz in the full motor should be
six times as many as in the 1/6 motor. This is why the whole partial
motor concept works.
>
> Another potential problem is if the motor is new and the rubber is
still stretching your .7 in-oz of launch torque may really be a lot less
by the time you get the motor on the model.
>
> None of this is intended to sound preachy. I'm just trying to figure
out where you are in the learning curve.
LeRoy Cordes
Chicago, Illinois
AMA 16974
In God We Trust
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Received on Thu Mar 25 2010 - 15:27:37 CET