I have the "plastic shark fin" type (landshorter.com), and they seem to work fine for me. They have their own claims as to why they are better. But the only thing I can confirm, is that they are cheaper than the others.
Dennis here, has the PNW ones on his Elite (same placement as mine), and they seem to work very well for him, too.
Can't remember who, but I thought someone mentioned on the list said that they didn't do anything for elevator authority. However, I thought someone else tried them there and they did help, so not sure about that. I was thinking of trying it on my Rebel, just to see if there is any difference. Having said that, I don't have any problem with the Rebel on floats as to elevator and hor stab effectiveness. I think the extra speed (airflow) for landing on floats is enough to keep the elevator effective. But then again, I may not know what I am missing.
Walter
----- Original Message -----
From: Ted Waltman <ted@vafm.org>
Date: Tuesday, October 13, 2009 9:42 am
Subject: [rebel-builders] VG location--from a VG manufacturer
To: rebel-builders@dcsol.com
See the vendor comments below regarding the discussion on the
builder's list
regarding VG location. Al Paxhia and I both have their
VG's on our Moose.
Link to their website: http://www.pnwaero.com/
Ted Waltman
From: PNWAero [mailto:aero@pnwaero.com]
Sent: Friday, October 09, 2009 9:34 AM
To: Ted Waltman
Subject: RE: VG location--existing customer
Hi Ted:
In regards to your question: I generally start at 10% of the
chord and have
never placed them further back than 11% because of loss of
effectiveness. I
very rarely go past 9% because of the potential for loss of top
speed of the
aircraft. All measurements are to the leading edge of the VG not
to the
center of the VG. The chord is measured with the flaps up.
This information is based on our blade style VGs that we
manufacture which
includes the same shape that the certified aircraft use. It's
our experience
over the years that the delta shape (or shark fin) type of VG is less
effective and may require a different location.
Hope things are going well for you.
Best regards,
Jerry
Pacific Northwest Aero LLC
-----Original Message-----
From: Ted Waltman [mailto:tedwaltman@gmail.com]
Sent: Thursday, October 08, 2009 7:55 AM
To: aero@pnwaero.com
Subject: VG location--existing customer
Hello folks!
I've had your VG's on my Moose for several years. Great
product, as my
testimonial on your website indicates.
There's a debate going on within the Moose builders email list
regarding VG
location. One figure being discussed indicates that the
center of the VG
should be at the 10% chord location.
I have two questions:
- Do you
have any general recommendation based on customer or your
own experience regarding % chord location for VG's?
- Is %
chord established by measuring from the front of the wing to
the trailing edge of the flaps-with the flaps up or down (I
assume down)?
Thank you,
Ted Waltman
Murphy Moose
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