The Murphy Builders Site

Hi, I have had the VG's on the leading edges of my Rebel and underneath
horizontal stab. I also have a countersunk leading edge only, i.e. not
the whole wing. As far as I am concerned their effect is less than
minimal, I repeat, on a Rebel. bobp that ferried my machine from Atlanta
to here in New Hampshire, thought it hilarious to have VG's on a smooth
leading edge and also thought they effected the lateral control.
Whatever. After all the frozen snow this year that limited my flying out
of my strip to about five months' worth! I am selling my machine this
spring at a very reasonable price. Anybody? Geert Frank Rebel # 083R




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Here are a couple of links to some inexpensive VG's. Of course it would be
simple to just make your own.







http://www.landshorter.com/index.html



http://computer-certainty.com/





Scott











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Hi Scott !

You can add VG's if you want - personally, based on my experiences
with the Rebel (and Moose) airfoil, the benefits are hard to measure, and
the disadvantages are significant. I found that they destroyed the wonderful
lateral stability, and prevented safe spins, degenerating into spiral dives
almost immediately ! Also, make snow removal & washing very difficult.
I've heard the many stories about tremendous improvements - just haven't
ever experienced them myself.

If you want proven improvements, go with the aftermarket wingtips
and the McKenzie STOL kit (leading edge cuffs & fences) !!

Just MHO ..... YMMD !!! ;-) :-) :-)

........bobp

-------------------------------orig.-------------------------
On Monday 20 September 2004 06:00 pm, Scott Aldrich wrote:

Here are a couple of links to some inexpensive VG's. Of course it would be
simple to just make your own.







http://www.landshorter.com/index.html



http://computer-certainty.com/





Scott











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Is there anywhere online that you can look at the McKenzie STOL kit? I would
like to see a picture of the leading edge cuffs.

Thanks, Brad




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I agree, the benefits of any change is going to be hard to measure and most
claims of improvement may be biased toward what was hoped to be achieved.

As far as actually Moose's go there is not a lot to report, but Bob Howell
has commented that the vortex generators greatly improved the flight
characteristics on his. And that the vortex generators were much more
effective than the leading edge cuff (I don't know off hand what cuff he is
using). I suspect a lot depends on placement along the chord, how many,
etc. I have not found out yet exactly were Bob placed his.

My plan is to leave everything off and get some half way accurate data for
my particular aircraft for comparison and then experiment.

Scott

-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com] On Behalf Of Bob
Patterson
Sent: Monday, September 20, 2004 5:02 PM
To: rebel-builders@dcsol.com
Subject: Re: VG's


Hi Scott !

You can add VG's if you want - personally, based on my experiences
with the Rebel (and Moose) airfoil, the benefits are hard to measure, and
the disadvantages are significant. I found that they destroyed the
wonderful
lateral stability, and prevented safe spins, degenerating into spiral dives
almost immediately ! Also, make snow removal & washing very difficult.
I've heard the many stories about tremendous improvements - just haven't
ever experienced them myself.

If you want proven improvements, go with the aftermarket wingtips
and the McKenzie STOL kit (leading edge cuffs & fences) !!

Just MHO ..... YMMD !!! ;-) :-) :-)

........bobp

-------------------------------orig.-------------------------
On Monday 20 September 2004 06:00 pm, Scott Aldrich wrote:

Here are a couple of links to some inexpensive VG's. Of course it would

be

simple to just make your own.







http://www.landshorter.com/index.html



http://computer-certainty.com/





Scott











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Has anyone had any experience with vortex gnerators on a Rebel ? Do
they work with Dave fife's wing tips?
I use the digest mode, so thanks in advance.
Allen H.



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Hi all,
Thought I'd respond to Bob P's comments on the vg's (and we all know how
much he loves them) and his feeling about the loss of cruise speed.
To begin my Rebel has the first set of Fife tips and the McKenzie cuffs. I
do feel that is enough.
On the other hand, a close friend and engineer worked to develop the vg's
for his record setting Longez. He spent alot of time in a wind tunnel with
Aero engineers The results? he took his normally aspirated 160hp to 30,0127
ft. It's in the books. His loss of cruise speed? Remember were talking about an
engineer, was 2mph. He lessened his landing speeds by 9mph. Don't forget
that drag increases quickly at higher speeds so the longez would be much more
susceptible to cruise loss. So when Bob P said he felt the vg's were causing a
loss of 3-5 mph I had to speak up. I HIGHLY doubt they could make even a
difference that could be registered! Two friends with them on their Beech
Barons cannot tell the difference in cruise, but sure can on landings!
Bob then speaks of the "mini" vg's the rivet heads may create,( in
previous posts) and how they don't effect the speed, or at least the time spent
flush riveting all of those is a waste. And they are not in the correct position
to help the air flow stay attached!
Bob, I've always trusted your opinions. Please don't cause your
credibility to be lessened by quoting numbers without basis, just a gut feeling.
My friend is still bugging me to install vg's on my Rebel. Maybe I should
just to lay this to rest! I did enjoy the testing stage!
Now that I've expressed MY opinion (grin) I think I'll go fly!
Keep at it, it's
worth it!
Curt N97MR




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