Seems everyone likes to talk about variable diameter props (VD)
but hardly anyone does anything about it, excepting Jim Richmond, of
course. I was inspired to try my hand at VD after seeing JR put up a
casual test flight of 33 minutes at Kibbie Dome Annual 2005. That
flight only got to about 100 ft high, which appealed to me. The
first day of Team Finals 2007 I started out with a variable pitch (VP)
for a first flight of 32:47. But I knew I needed to find another 90
seconds somewhere to stay in the hunt, so after round 2 I decided to
try my just-finished-never-flown VD prop. Because I seemed to make
slow, steady progress in adjustments in getting it to work, I
unfortunately squandered the next two days of Team Finals,
essentially just test flying, with too-slow improvements to show.
But the excitement of getting the occasional "good fold" kept me
committed to keep trying past a point when I should have gone back to
tweaking the VPs instead. Half my problem was also high torque
launch problems--stalls at anything over .39 in-oz. Eventually
solved that (thanks, Tim Chang) and finally the VD seemed promising.
But only after TFs were over, I got a "Kibbie Dome Annual" official
time of 31:27 with the VD, climbing about 110 feet high, folding at
13 minutes, and using all turns in a 9" motor. That flight is still
begging me to continue with the VD concept, and so I shall. VD will
not make a good flyer out of a mediocre flyer, but I think it offers
potential at least as good as VPs.
One modeler asked if I had any advice for the those wishing to try
build a VD. Yes. Don't suppose you will master it the first day at
an important contest! Seems at every big contest I keep relearning
the lesson, "Stick to what you know when it really counts."
Hopefully next time I will know, not merely believe that VDs work
well. (Anyone here is free to email me for any other VD details, as
far as I know them.)
Congratulations to Jim Richmond, John Kagan, Doug Shaefer, who will
represent the USA very well at Belgrade, 2008, as also will the Jr.
team--Tim Chang, Molly Neering, and Ethan Aaron.
Mark Bennett
Received on Thu Jul 12 2007 - 14:41:30 CEST
This archive was generated by Yannick on Sat Dec 14 2019 - 19:13:45 CET