Re: New Group Member

One Sky Dog

On my Dragonfly GU canard flight tested 50% chord pairs 1.5” spaced 4” between pairs. No effect on top speed but eliminates the separation bubble that forms ahead of the elevator hinge line. No more puddles of standing water in rain and pitch change.

Works for me!

On Thursday, September 30, 2021, 8:24 AM, Jay Scheevel <jay@...> wrote:

I think that Corbin’s VG’s are properly located for the GU (lateral spacing is also important). He can measure them for you, or perhaps Martin Skiby has those measurements.





From: <> On Behalf Of quickieq2uk via
Sent: Thursday, September 30, 2021 9:18 AM
Subject: Re: [Q-List] New Group Member


Hi Brent, 


It’s been a long time since I put my VGs on or even flew my aircraft. But your VGs look to be way too far aft to be doing anything useful. Most aircraft have their VGs installed 8-12% of the chord back from the leading edge however this is too far forward for the GU-25 airfoil. Most people seem to put them at 40-50% of the chord aft of the leading edge. I think mine are at around 40 something percent from memory, I think the point of maximum curvature of the upper surface is about that percentage of chord aft. 




Simon Wilson


United Kingdom

On 30 Sep 2021, at 15:53, Brent Sherstan <brent.sherstan@...> wrote:

Jim: I'm glad you mentioned the VG's, that was one of my questions. They are on the canard but farther back than I would have expected, I'll be at the airport this weekend and will take a picture. Does anyone know the proper location for VG's? Should they be at the peak curvature point on the wing, the point of maximum thickness? Mine are certainly aft of that.

Mike: I'm actually not sure of the climb rate yet, I have a new prop to try out and haven't got that far, hopefully this weekend. I agree about the little vents, I've done a few flights at 80 degrees and I was nearly soaked after an hour! I was thinking a tinted canopy and/or stick-on sun visor might be the solution?

Dave: I'm curious about your Revmaster CHT sensors. I have them located where Revmaster suggests (a hole drilled near the outer head stud, near the exhaust valve). I have an MGL TC-3 and I can't get a reading that I trust. I've checked the sensors in a boiling pot of water and they're right on, but when flying I haven't seen a reading over 300 degrees. Now, I've done a lot of work to make it cool but I don't believe I've done that good of a job. No one has ever heard of a VW running cool and I just don't believe it. Where do you have yours and what numbers were you seeing? Sorry about your latest troubles by the way, amazing job getting it on the ground! Hopefully you're back up in the air soon!

Thanks guys, I definitely plan to head South when I've got it all sorted out!

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