What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

RV-3A Vertical Stabilizer: how much offset with an O-320 & Catto 2 blade?

Jumbo

Well Known Member
Hi all,

I hope you all have had had a Merry Christmas and today: Happy New Year!!

On the -3 which I have imported in spring 2013 from the US a couple of friends have improved a lot: partly new wiring under the panel and relocation of the battery (could not brake on the LH side due to the battery tray when LE rudder was applied), safetied all nuts and bolts for aileron and rudder / elevator, new alternator and cosmetics (i.e. fairings ?). All great now.

However the rudder is built-in with a 5 degree offset which actually is a bit much and the trim tab needs to reverse a lot of rudder offset (don?t need any rudder deflection on TO ?) and we want to correct this by building a new mounting bracket for the rudder stabilizer.

My questions (I am not the builder): how much offset should we use for the rudder stabilizer on the -3 with an O-320 & Catto 2 blade propeller?

You guys could do me huge favor if you?d let me know your experience re this.

Many thanks and have a great RV-filled & safe 2014, Heinz
 
RV3 rudder

Plans for RV3 have never specified V-stab offset (I assume that is what you meant, as you can only trim the rudder, not put offset into its positioning). Plans have shown, however, an engine mount offset (I *think* offset to the right, aiming the prop slightly right - do the torque math). I have never heard of anyone building with a V-stab offset, esp. with an 0-320, which doesn't need it on this airframe. Most RVs are trimmed in rudder for cruise flight, and require some right boot in takeoff and climb (and left boot in descent).

- Steven
800 RV3 hours
(another one last monday!)
 
Our stab is straight with the fuselage Heinz - no offset. We added a small trim tab during flight testing to make it fly straight at cruise, and very tiny rudder pressures are required at other speeds if you want the ball perfectly centered. And you won't notice if you don't.

Paul
 
I cant say for sure on the 3 but I did a WAG on my rocket and set the VS leading edge one quarter inch to the left of center line. It flys with the ball in the center in cruise no trim tab on the rudder. Hope this helps.
Ryan
 
valuable information, indeed

Folks,

many thanks for your replies - we?ll know what to do now.

Again, fly safe in 2014 and talk later, Heinz
 
I researched this prior fitting our VS, including Paul's advice / thoughts. We put in a small offset (as above, plans call for none), maybe 1/8"? Aim was to reduce rudder required in cruise, but would rather "undershoot" than "overshoot" the optimum amount.

Edit: Measured at 5/32", which over the 24" of the VS equates to 0.4deg.
and we want to correct this by building a new mounting bracket for the rudder stabilizer.
I am intrigued how you aim to do this? The VS front attachment goes onto the HS, in turn the HS uses a "mounting bracket [angle]" onto the fus. Redoing the angle will also alter the sweep of the HS? Just take care, since pretty much failure of the front VS attachment = end of aircraft and maybe pilot :mad:
 
Last edited:
VS offset

I have done the same as Andy Hill. My search of posts indicated about 1/8" was good for an RV3. I can send pics on the setup and measurement if interested...Larry
 
ok, so about 1/8" might be good, too

Andy, Larry,

many thanks. We will look at that and of course be careful but thanks for pointing this out.

Larry, indeed some pics will help so if you could e-mail mt at 'heinz dot leuters at gmail dot com' please?

Again thanks, Heinz
 
build a new bracket

Mission accomplished - offset removed by building a new bracket which moves the rudder stablizer using same holes in the airframe however holes in a new place in the top of the bracket and all new bolts (this picture was taken before taking the bracket out):

2sacwg7.png


This is the angle which we have corrected as per plans, no offset now (quite some offset we started from ... I have no idea why the original builder did this, to be honest):

25kkfaw.png


Before the change the plane flew with wings level but with certainly more than a full ball off nose pointing to the right at 135kts IAS. It took quite some left rudder to center the ball. Now the ball is centered and we can still play with a trim tab if we want to do so. I now have to deal with a heavy left wing however I can start from here with the ball centered (as per Van´s recomandations).

Andy, we did not touch the HS attachment at all and we just replaced the bracket using existing holes in the airframe (only the top holes in the bracket were moved to the side). My builder friends Wolfgang and Daniel were happy to do so and are happy with this - gives me peace of mind.

Best, Heinz
 
Last edited:
Intersection fairing

If you change the vertical stabilizer you will also need to make a new intersection fairing...
 
yep - indeed

Robin,

the fairing is in the making ... Daniel, who is a fiberglass genius and already has redone the gear leag fairings and the wheel pants, is on the case as I write this.

Best, Heinz
 
Back
Top