Gary
I assume you're talking about classes with fixed pitch props. I wish I knew the definitive answer, but don't. All I can say is that I tend towards more camber, moderate prop pitch and a lot of heavy rubber.
Here's an example of 2 different approaches at Kent 2007 (59' max prefab metal building with large solid girders):
In LPP, Jim Richmond's new record flight spent several minutes bouncing off the ceiling. My best flight topped out a little above the bottom of the girders and spent most of the flight just below the girders after a couple of soft hits. I think Jim was using rubber in the .080 range while I was using over 2 grams of something in the low .090's. Jim won which by definition means that his way was better. In a more cluttered site like you're describing the results MIGHT be different but a lot depends on nerve and luck.
Another example:
A few years ago Chris Borland, Chuck Markos and a few other people were doing amazing times in Science Olympiad with very small rubber and low pitch props. People around here were using high pitch and big rubber and doing very well in competition but not doing times comparable to what Chris was doing. I've never really figured that one out.
Anyway, my answer - at least what I attempt to do - is try to slow down the climb with more camber and more pitch, then get into the cruise phase after a few gentle hits. I use the heaviest rubber I can get away with to extend the cruise. What I try hard to avoid is being in a steep climb when I hit the ceiling so that my model doesn't go over the obstructions between hits.
----- Original Message -----
From: Warthodson_at_aol.com
To: Indoor_Construction_at_yahoogroups.com
Sent: Thursday, November 27, 2008 9:15 AM
Subject: [Indoor_Construction] Fwd: low ceiling high duration
----------------------------------------------------------------------------
From: Warthodson
To: Indoor_Construction_at_yahoogroups.com
Sent: 11/26/2008 9:54:31 A.M. Central Standard Time
Subj: low ceiling high duration
I am interested in hearing what strategies seem to work for increasing duration in cluttered low ceiling sites. Particularly sites where it is not practical to spend much time "scrubbing" because of the clutter & high likelyhood of getting hung up. Assume making the airplane (less rubber) lighter is not an option.
Are airfoils with greater camber of any help? Would you agree that for high ceiling sites, cambers seem to be 3% to 5%? How about low ceilings?
In categories with no limit on rubber weight what seems to be better:
Low pitch props & thin rubber or higher pitches & thicker rubber, or some other combination? I.E. How do you optimize the "area under the curve" of the rubber when you are limited to a low ceiling & minimal scrubbing?
Thanks,
Gary
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Received on Thu Nov 27 2008 - 07:58:21 CET