REFLECTOR: Aileron Rigging

cgputney at peoplepc.com cgputney at peoplepc.com
Tue Jul 8 19:49:53 CDT 2008


Ron, did your change result in 2.5" down and up?   I want to do this change 
as well and would appreciate some numbers on your actual final measurements. 
Thanks,
Gordon Putney

----- Original Message ----- 
From: "Ron Brown" <romott at mi-connection.com>
To: "Velocity Aircraft Owners and Builders list" <reflector at tvbf.org>
Sent: Sunday, July 06, 2008 12:13 PM
Subject: Re: REFLECTOR: Aileron Rigging


> Hi Joe,
>
> From my RC modeling days, I learned that to minimize adverse yaw, the
> ailerons should go up more than they go down.  Although we have Frieze
> ailerons (the nose sticks down when the aileron is up), there is still a
> tendency toward adverse yaw.  Especially since the attach point for the
> aileron cables at the back of the keel is not 90 degrees.
>
> So, to improve the situation, I installed my aileron bell cranks beside 
> the
> engine with a good bit of bias toward the front.  I also lowered the 
> attach
> point for the aileron cable jacket.  This helps relieve the "error" at the
> keel as well as move the bellcranks away from the engine (but your rotary 
> is
> narrower than the Lycoming so not an issue).  The aileron bell crank is 
> more
> like 90 degrees to the cable when the aileron is down.
>
> Here's a note that I wrote in 2003 that is repetitive but adds some more
> info:
>
> When I rigged my ailerons, I found it difficult to obtain the equal 2.5" 
> up
> and 2.5" down that is called for in the manuals - for my 173 Elite RG.
> Since the push/pull cables at the rear of the keel do not have a 90 degree
> approach angle, the connection of the push/pull cable at the aileron 
> torque
> tube on the wing, results in ailerons that travel down more than they do 
> up.
> This causes an adverse yaw condition which will lead to wallowing at low
> speeds.
>
> I learned this lesson a long time ago when flying RC models.  If you take
> off at just above stall speed, the model would turn the opposite direction
> from that commanded.  This is because the aileron that is going down has
> more drag than the one going up. This causes the left wing to slow down if
> you are commanding a right turn at slow speeds.  This is called adverse 
> yaw
> and is common in older airplanes.  To get a coordinated turn, even at 
> speed,
> you need to lead with a lot of rudder before applying aileron deflection.
> Or, you rig the ailerons so that there is more up travel than there is 
> down
> travel, which will reduce this yaw effect.
>
> Cessnas and some other planes (including our Velocities) have a Frieze
> aileron, which features a lip that hangs down below the wing when the
> aileron is deflected upwards.  This helps balance the drag from the other
> aileron which is hanging down in the airstream.
>
> Velocities handle fine at higher speeds even with no rudder input.  But at
> lower speeds, if the ailerons are rigged with the 90 degree approach angle
> at the wing, then this results in more down than up aileron travel, and 
> the
> adverse yaw condition that some folks have called "wallowing" on final.
>
> A while back, Dave Black pointed out the problem at the keel.  One fix is 
> to
> build a wide bellcrank at the back of the keel so that the aileron cables
> could be attached at a 90 degree approach angle while in the neutral
> (centered) condition.
>
> The other way is to attach the aileron cable at the wing so that the
> approach angle is more than 90 degrees.  Mine are attached at about 120
> degrees, which results in more up travel than down travel.  My Velocity
> handles fine at low speeds, with just aileron control, similar to my 
> Cessna
> 172.  If I need a sharper turn, I'll kick in more rudder, just like in my
> 172.  But normally, no rudder is needed, all the way down to the runway.
> (But I also installed VG's before my first flight, these also improve low
> speed aileron control).
>
> Ronnie Brown
>
>
>
>
> ----- Original Message ----- 
> From: <jewen at comporium.net>
> To: "Velocity Aircraft Owners and Builders list" <reflector at tvbf.org>
> Sent: Saturday, July 05, 2008 11:42 AM
> Subject: REFLECTOR: Aileron Rigging
>
>
>>I am rigging up my aileron this weekend (173RG.)  I recall several threads
>>on the subject in the past, but can't find my notes.  Does anyone mind
>>refreshing me on the nuances that the manual does not address.
>>
>> Thanks,
>> Joe
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