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pcondon(at)mitre.org
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 Posted: Tue Jan 17, 2006 5:25 am Post subject: has anyone dimpled their XL? Dimpled Vs. Raised rivets |
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Mark, your numbers are off. Mooney aircraft tried to use the less labor
intensive method of using raised rivets heads on some Mooney's produced
by Butler/Avstar in the early to mid 60's. On the wing from Leading
edge to spar they used raised head rivets in addition to other frontal
area(s). Speed loss was dramatic at over 10 knots indicated. Later
Mooney's went back to the countersunk rivets in the critical air flow
areas. Mooneys cruse at 160 knots. The Zeniths certainly less, but I
would expect a larger difference then what you stated based on the
Mooney story. It's quite easy to back (face) a countersunk rivet by
shooting the tail and not the face of a rivet. Having built two RV's I
can say that. Is it necessary on a Zenith..that depends. Certainly not
(IMHO) for my 701. Other builders of faster Zeniths may want think this
out with the facts. (BTW, extra fuel capability is a "speed mod" that
many pilots don't think of.)
Time: 04:23:20 PM PST US
From: "Zodie Rocket" <zodierocket(at)hsfx.ca>
Subject: RE: has anyone dimpled their XL?
The effect of flat riveting over domed heads is 1/4 mph gain on speeds
below 200mph. IS the time worth it on an XL ? I doubt it, but if you
want to do it for looks then knock yourself out.
Mark Townsend Alma, Ontario
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mijniljj(at)yahoo.com
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| Posted: Tue Jan 17, 2006 6:56 am Post subject: has anyone dimpled their XL? Dimpled Vs. Raised rivets |
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This is an unreasonable comparison. The Mooney has a
laminar flow airfoil designed to have laminar flow to
about 40 percent chord (as far back as the spar) where
as the thick blunt airfoil on the Zenith is a
turbulent flow airfoil, it is amazing that you would
get any increase in speed from flush rivits since the
airfoil as turbulent flow from near the leading edge.
Jim
--- "Condon, Philip M." <pcondon(at)mitre.org> wrote:
| Quote: |
M." <pcondon(at)mitre.org>
Mark, your numbers are off. Mooney aircraft tried to
use the less labor
intensive method of using raised rivets heads on
some Mooney's produced
by Butler/Avstar in the early to mid 60's. On the
wing from Leading
edge to spar they used raised head rivets in
addition to other frontal
area(s). Speed loss was dramatic at over 10 knots
indicated. Later
Mooney's went back to the countersunk rivets in the
critical air flow
areas. Mooneys cruse at 160 knots. The Zeniths
certainly less, but I
would expect a larger difference then what you
stated based on the
Mooney story. It's quite easy to back (face) a
countersunk rivet by
shooting the tail and not the face of a rivet.
Having built two RV's I
can say that. Is it necessary on a Zenith..that
depends. Certainly not
(IMHO) for my 701. Other builders of faster Zeniths
may want think this
out with the facts. (BTW, extra fuel capability is a
"speed mod" that
many pilots don't think of.)
Time: 04:23:20 PM PST US
From: "Zodie Rocket" <zodierocket(at)hsfx.ca>
Subject: RE: has anyone dimpled their
XL?
<zodierocket(at)hsfx.ca>
The effect of flat riveting over domed heads is 1/4
mph gain on speeds
below 200mph. IS the time worth it on an XL ? I
doubt it, but if you
want to do it for looks then knock yourself out.
Mark Townsend Alma, Ontario
browse
Subscriptions page,
FAQ,
http://www.matronics.com/Navigator?Zenith-List
Admin.
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zodierocket(at)hsfx.ca
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| Posted: Thu Jan 19, 2006 5:01 am Post subject: has anyone dimpled their XL? Dimpled Vs. Raised rivets |
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Phillip, you could most certainly be right, my numbers may be off. I'm
not a designer, and to work through the math involved would require more
asprin then I would care to take. So, I got the numbers from Chris
Heintz and though he could possibly be wrong I tend to believe him when
he says that the speed gain is minimal for the work involved.
Mark Townsend Alma, Ontario
Zodiac 601XL C-GOXL, CH701 just started
www.ch601.org / www.ch701.com / www.Osprey2.com
do not archive
--
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