I don't have any proof either (have the regular tips on my Rebel), as I have
not spent a lot of time flying side by side with Fife tip planes. But just
going by numbers others have quoted, my plane was always on the fast side
when it came to cruise (even before my engine upgrade). Although I think it
had more to do with my prop selections.
My understanding on the theory of the Hoerner tips is that the reduced
induced drag benefits are at lower speeds, and also therefore improves climb
rates. The MAM extended droop tips should do the same thing, except for
maybe slightly more parasitic drag with the bigger wing area at higher
speeds.
The biggest speed increase, though, without a doubt, is the use of flaperon
reflex in cruise.
Walter
-----Original Message-----
From:
mike.davis@dcsol.com [mailto:
mike.davis@dcsol.com] On Behalf Of Ron
Shannon
Sent: Tuesday, March 08, 2011 8:48 AM
To:
rebel-builders@dcsol.com
Subject: Re: [rebel-builders] Fife wing tips -
Jeff, I don't have hard numbers, because 254R has always had the Fife tips.
However, before I first got the project 5 years ago, my impression from
researching the archives was that the Fife Hoerner tips would add somewhere
on the order of 4-5 MPH compared to MAM originals. I do know I have gotten
some pretty good performance with just 120 HP, even before installing any
fairings, and I'm inclined to attribute a good deal of that to the tips,
which are the only non-standard aerodynamic component.
Based on the consensus in the archives, and knowing of the delays, I ordered
the tips within two months of first buying the project. They were first
supposed to be delivered in 3 months -- it took 8. I think it would be nice
if Dave would license someone else to produce these from his molds, but he's
not the only supplier who is (so far) holding onto a design. We occasionally
wish MAM would second-source some of its custom parts too.
Whatever the absolute performance improvement is, it could presumably be
duplicated by any "similar" Hoerner tip. However, it would be a challenge to
reproduce the Fife design without a significant investment in molds, because
they are not just a uniform straight angle up from bottom to top, as are the
Zodia Hoerner tips, for example, and many others. Instead, they have rather
exquisite compound curves that would be difficult to reproduce in anything
but composites. Two photos at
http://n254mr.com/node/1151 will give a sense
of the complex shape, and beauty, of these tips.
Ron
N254MR
On Mon, Mar 7, 2011 at 11:46 PM, Jeff Micheal
<
westcoastkitplanes@gmail.com>wrote:
Ron,
How much is the speed increase?
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