--- In Indoor_Construction_at_yahoogroups.com, "Bill Gowen" <b.gowen@...> wrote:
>
. . .Optimal pitch is the one that gives you the highest flight time. . .
>
. . .Adjust the cruise first. Get the best combination of prop pitch and model trim for the
cruise. Then go for the ceiling height with launch torque adjustments. . .
Brant, our experience with SO planes agrees with what Bill has suggested. Last year my
students modified an Ikara prop so that had an adjstable hub that allowed for changes in
pitch. They set the pitch, then made several flights each with a variety of rubber sizes that
differed by 0.005". They found that there was a range of pitches that seemed to give them
pretty comparable times if matched up with the appropriate rubber size.
If the pitch was higher than this range, flight times dropped - it was tough to get it all the
way up to the top. If the pitch was too low, the plane climbed so well that they had to back
way off on the turns, and the times were lower as well.
One interesting thing we discovered at last year's state competition: the students had
found what they considered an optimal combination of pitch and rubber by flying half
motors in our gym. But at the competition, the plane just wouldn't climb out, even when
launched at a much higher torque than they had used in practice. When we got home, we
measured the pitch of the prop they had been using - it had changed to a higher pitch! So
I guess when they heated/twisted it to repitch it, it relaxed over time back toward the
original pitch.
Has anyone else seen this problem with repitched plastic props? If so, any suggestions as
how to prevent it?
Dave Drummer
Kutztown Sr. High School
Received on Thu Nov 30 2006 - 06:32:52 CET
This archive was generated by Yannick on Sat Dec 14 2019 - 19:13:44 CET