REFLECTOR: Low Speed Handling

[Richard Riley]

At 06:04 AM 5/26/05, you wrote:
>Here's my 2 cents on low speed handling:
>
>1.  The Velocity aileron control geometry causes the ailerons to go down 
>more than they go up.  I feel this differential is backwards from the 
>preferred "more up than down" aileron travel.  This is due to the "wrong" 
>approach angle of the push/pull cable at the rear of the keel (Thank You 
>Dave Black!).  This can cause adverse yaw at low speeds.  Using a lot of 
>rudder can counteract this adverse yaw and minimize the wallowing on 
>final. I installed my aileron bell cranks at the engine with a lot of 
>forward angle when the aileron is up.  This corrects the bad approach 
>angle at the keel. I feel my 173 handles well at lower speeds - and 
>required for Lake Norman Airpark with all of the tall trees around the 
>airstrip.

 From my alternate reality -

Vari Eze's, Long EZ's, Cozy's and Berkuts don't have the geometry 
oddity.  They use pushrods all the way back to the ailerons, and the final 
pushrod hits the aileron bellcrank at 90 degrees with everything 
neutral.  Nonetheless, at low speeds all have significant adverse yaw and 
dutch roll.  Below about 100 knots you lead with rudder.  It's an artifact 
of the highly swept wing.


>2.  VG's on the wings can help improve aileron effectiveness at lower 
>speeds and hence improve handling on short final.  And as I mentioned in 
>an earlier note, VG's on the canard can also improve low speed elevator 
>effectiveness. I do not have the elevator cuffs installed - this also 
>improves low speed elevator effectiveness.

On the above aircraft VG's help adverse yaw some.  So do trailing edge 
fences.  See 
http://web.archive.org/web/20040208220441/lsecorp.com/KlausInfo/Flowfence.htm 
(It's not on Klaus' site anymore)

On most Berkuts we have a little, vestigial lower winglet that diverts TE 
spanwise flow at the tip.  One plane, N600SE, didn't have them, and ended 
up with a LOT of dutch roll on final.  TE fences helped, but clearly the 
lower winglet did a lot in that area.  It wasn't much - it went from 
nothing at the thickest point of the wing, straight aft, so at the wing TE 
it hung about 1.5" below the TE.

I DON'T know if any of this would work on the Velocity, it is a different 
wing and winglet.  But they're possibilities.




>All of the above are my opinions - based on my subjective experiences.  I 
>have flown three Velocities - the Factory 173 Trainer, a Standard with 
>standard wings, and my 173 Elite.  All three have VG's.  I feel all three 
>handled well at low speeds - well enough that my 800 hours of 172 
>experience was pleased with the handling of these Velocities on short final.
>
>Ronnie
>
>
>
>
>
>----- Original Message ----- From: "Pat Shea" <xl340hp at yahoo.com>
>To: "Velocity Aircraft Owners and Builders list" <reflector at tvbf.org>
>Sent: Wednesday, May 25, 2005 10:57 PM
>Subject: Re: REFLECTOR: Runway length
>
>
>>It's interesting that a while ago there was a thread
>>going from guys with poor low speed handling
>>characteristics (mostly XL's) who were compensating w/
>>high approach speeds (85KIAS to 90KIAS range)- now
>>we're hearing from guys that are close to canard stall
>>speed (65KIAS - 70KIAS range) on approach and/or
>>landing. 20 Knots is a pretty impressive spread!
>>
>>I'm at 85KIAS over the numbers w/ and XL going into
>>3,200' using the standard Matco's.
>>
>>Pat
>>
>>--- John Dibble <aminetech at bluefrog.com> wrote:
>>
>>>I think there is a big difference in stall
>>>characteristics between the
>>>XL and STD Velocities, or maybe it's a variation due
>>>to individual
>>>building.  Either way, my SRG is light in front.
>>>With 2 up front (350
>>>lbs) and 20 gal fuel, I can stall (a mild
>>>oscillation) at 70 kn on short
>>>final and the stall will go away when I'm in ground
>>>effect and I can
>>>land without the nose hitting hard.  An extra 10 kn
>>>makes a big
>>>difference (psychologically) when you're trying to
>>>land on a short
>>>runway.  I recommend doing a slow speed stall to see
>>>how strong the
>>>bucking is.  Know how to avoid deep stalls as
>>>previously discussed.  If
>>>the bucking is extremely gentle, you can probably
>>>expect the same when
>>>landing and not need a lot of extra speed.  Of
>>>course the first attempt
>>>is best on a 5000' runway.
>>>
>>>John
>>
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