Re: Re: Hints for Cat IV LPP flying

From: Bill Gowen <wdgowen_at_gmail.com>
Date: Wed, 24 Mar 2010 23:55:03 -0400

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.

  
Received on Wed Mar 24 2010 - 20:55:09 CET