Kang, I know I replied to this before but I just confirmed that the flyer
you asked about in the video was Jeff Annis who Ray Harlan recently
attributed the pioneering work on the VP for indoors. I knew he was a
recent returnee to indoor but didn't know about his credentials other
than his beautiful planes.
This is the excerpt from Ray Harlan's email:
"The earliest concept of a VP for indoors that I know of is on p. 74 of
the '37 Zaic yearbook (same page as the torque burner). It is by R Hammer
and uses a compression spring and bent wires through the prop hub to
effect what looks to be decreased pitch with increased motor tension.
Perhaps Zaic didn't draw it correctly.
However, the real pioneer of workable VP props was Jeff Annis. He
puplished the paper "Torque Variable-Pitch Propeller" in the 1975 NFFS
Symposium. It shows a mechanically workable design employing the torsion
spring characteristics of the prop shaft. He had tested it prior to
publication and had found 15-30% better duration over a flaring prop in
low ceilings.
It took quite a while to lead to better designs of the VP prop. The Brits
tried at the '80 WCh, using essentially the Annis design, but couldn't
get it working well (see Aug. '82 INAV). Jim Richmond introduced his VD
prop in'84 in Chicago and used it at the '84 WCh where he won the contest
with it. After a flurry of activity with VD props, only two fliers were
successful with them - Jim Richmond and Rich Doig. Attention returned to
VPs. Ron Higgs tried one with a spiral spring in '85 and set a Cat I
world record. At this point my collection of INAV is a bit thin. In Dec
'90 Bob Randolph set a Cat I record with a VP prop that looks much like
the classic Banks/Brown design. The prop doesn't use a preload adjust
screw, just a high limit screw (May '91 INAV). I don't know who was
first. I thought it was Cezar Banks who finally developed a compact wound
torsion spring design. Steve Brown made the technology accessible with
his excellent article on how to build a VP in the Oct '96 issue of INAV.
The current VP designs are only small variants of this design."
On Thu, 19 Jan 2012 19:48:03 -0000 "Yuan Kang Lee" <ykleetx_at_gmail.com>
writes:
> Nice to see more F1D's flying. May I ask who were the F1D fliers?
>
> -Kang
>
> --- In Indoor_Construction_at_yahoogroups.com, "icefishdiced"
> <icefishdiced_at_...> wrote:
> >
> > Here are the videos I took in December
> >
> > http://www.youtube.com/watch?v=NssKBs1d8rY
> >
>
>
>
>
> ------------------------------------
>
> Yahoo! Groups Links
>
>
>
>
>
LeRoy Cordes YOLO
Chicago, Illinois
AMA 16974
In God We Trust
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Received on Thu Jan 26 2012 - 07:06:07 CET