I think not test flying on contest day is a sure recipe for disaster. I'm not smart or knowledgeable enough to know all the variables that affect an indoor duration model, but using test data from another site on another day is almost never going to get the best results at a competition. I think temperature can have an effect but humidity and atmospheric pressure almost certainly do as well. Here are some personal examples:
USIC 2003 - I launched my first F1L test flight at a launch torque of around .16 in-oz. The previous year the same model flew it's officials at a launch torque of over .2 in-oz. It went into the rafters and wasn't recovered until after the contest was over.
USIC 2004 - the night of the day before F1L and EZB my EZB did 7 1/2 minutes on a quarter motor and my F1L was doing 4 1/2 on quarters. The next day neither would even climb on the launch torque that I was using the night before. I had to go up in motor size drastically for both classes and never did get the right combination figured out.
Lakehurst last Labor Day - on Saturday when the hangar was really wet and drafty I pulled out my A6 to see if it would fly. This model had just done 9 minutes at USIC but wouldn't climb at Lakehurst.
At big contests you will see nearly all of the best fliers flying on partial motors to establish the best combination for that day. They are not just doing it for fun.
----- Original Message -----
From: calgoddard
To: Indoor_Construction_at_yahoogroups.com
Sent: Monday, February 26, 2007 1:10 AM
Subject: [Indoor_Construction] Flight Temperature
Our Science Olympiad team had a disaster at its regionals.
Their two planes climbed way too quickly and after many collisions
with the roof, scoreboard, basketball backboards, one plane ended up
landing on a light fixture and the other crashed.
They had tons of flight data compiled on half motor flights. We knew
the ceiling height of the competition site and planned for launch
torque for a conservative flight on the first flight. Both flights
climbed like rockets. The experts told us it was updrafts. All our
practice data was acquired in a gym in the low 60's F. and the
competition was in the mid to high 70's F. Our team did not do any
practice flights at the competition site for two reaons. First, our
main competition did, his plane hung up on light fixture and was
damaged. So we were spooked. Second, our team was pre-occupied with
other events and didn't really have the opportunity for test flights
in the competition site, which were limited.
What's the relationship between temperature and torque/winding? If
there is a 15% differential between the temp for the test flights and
the temp for the competition, do you lower launch torque by 15%?
What a shame, our students' plane hung up on a lamp 35 feet above the
floor after three collisions and was still in cruise when it stopped
at 1:45.
[Non-text portions of this message have been removed]
Received on Mon Feb 26 2007 - 06:35:52 CET
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