Very true. I was following the LPP discussion where most were looking at less than 1:1. From 1:1 to 2:1 there is 8.8% improvement w/o considering the ~10% reduction in viscous drag due to the ~20% higher Reynolds No.
Most LPP's have similar aerodynamics, so the most improvement comes from rubber ratio and a well matched prop.
Going from 0.8 to 1.6 ratio has a couple minutes potential. Probably requires a bit less pitch & a whole lot more clearance, but other than Tan III, what else has the potential?
More food for thought,
H
To: Indoor_Construction_at_yahoogroups.com
From: don_at_slusarczyk.com
Date: Sat, 6 Mar 2010 11:44:33 -0500
Subject: Re: [Indoor_Construction] Re: Optimum Rubber
2:1 works out mathematically but if you graph the relationship out you
will find that above ~1.4 to 1.5 to 1 the difference is off only by
about 2% of the theoretical maximum of the 2:1 ratio. Coincidentally
if you look at many 65cm rule F1Ds you find the rubber weight used then
was in the 1.4-1.5 gram range. Going above 1.5 to 1 generally is not
possible as the strength of the model can not handle a fully wound motor
of such weight. Imagine a 2.4 gram motor on a 1.2 gram F1D wound to
capacity. However some events do not follow this rule at all, LPP and
F1L are the first two which come to mind. LPP likes below 1:1 which may
be a result of the 12" prop limitation and 10" motor stick limitation.
F1L seems to like 1:1 possibly due to the motorsticks being somewhat
limited in length due to structural reasons. So it is not a steady rule
for all events.
Don
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Received on Sun Mar 07 2010 - 00:45:04 CET