REFLECTOR: Elevator Cuffs

[Chuck Jensen]

Scott/Joe,

As mentioned, a full set of VGs on the canard and none on the wings is a no-no since the canard needs to stall before the main wings and the added lift from the VGs on the canard may frustrate that design.

After painting, I left the VGs off both the mains and canard (XLRG).  Flight characteristics were unremarkable until I flew with a modest sized person in the front with me.  On slow final, there was a pronounced, and disconcerting, pitch oscillation that was not present with a single front person.

Per the suggestion of S. Baker and K. Mishler, and I believe Ronnie Brown piped in, I installed a half set of VGs on the canard which consisted of 3 pairs on each side.  This did the trick.  It put an end to the oscillation on final with better "plop" control so the nose could be set down instead of always plopping down.

In sum, a half set of VGs on the nose gives a little better lift and seems to work well but a full set of VGs on the canard with none on the wings, as Scott mentioned, is apparently not a great idea.

Chuck Jensen


-----Original Message-----
From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org]On
Behalf Of Scott Derrick
Sent: Thursday, November 15, 2007 8:57 AM
To: Velocity Aircraft Owners and Builders list
Subject: Re: REFLECTOR: Elevator Cuffs


Joe,

I went from Cuff's No VG's, to No Cuff's No VG's, to No Cuff's and VG's.

The first had gentle stall but reduced lift, second had the classic 
pitch buck stall(porpoising) and better lift, the last had the same 
stall characteristics and even better lift.  The last is my preferred 
configuration.

You are putting VG's on the main wing too, right?  VG's just on the 
canard would be a big no-no.

Scott

Joe Ewen wrote:
> Before I start grinding on my elevators (the ones I thought were 
> finished due to the nice shinny paint,)  I would like to check on the 
> preferred elevator configuration.  As I understand it, the best 
> configuration is no elevator cuffs and installation of VGs.
>  
> Thanks,
> Joe
> 
> 
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