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RV-3B Aileron bellcrank

Larry DeCamp

Well Known Member
The 3B bellcrank is steel. Supposedly, the earlier RV3 ailerons were lighter in feel and not steel. Can anyone confirm the older bellcranks were different, and how so ?
 
RV-3 Bellcrank

Hello Larry,
There is a world of difference between the original aileron bellcrank design and the current design. And, there is a noticeable difference in control feel/loading. The earlier bellcrank is basically attached to a main wing rib. In the current design, the aileron bellcrank is attached to the main spar web and does not provide the same differential throw. The geometry of both designs are completely different. And, the force feel on the current design is greater than the earlier design.
I have flown planes with both aileron designs and I prefer the lighter stick forces of the older bellcrank. The planes are just more responsive. Dave Sloan built his RV-3B after having built and flown an RV-6A. During his initial test period Dave modified the aileron bellcrank of his RV-3B to better approximate the differential throw of the original design. He said the changes noticeably improved the handling qualities. Jim Winning flew Dave's RV-3B before and after the changes and can further attest to positive change.
Chuck Brietigam
RV-3 (IO-320/ Hartzell) RV-6XL (TO-540/MacCauley)
 
No pics but Jim is a good friend of mine and I did see the bellcranks before and after he modified them. I'm sure Jim would be happy to modify the bellcranks for you if you provide him a set and a few bucks.
 
Older Style RV-3 Aileron Bellcrank

Anyone who has an older set of plans (like me for instance - S/N 11226, 1992) has the older bellcranks (and mounting) called out on their original plans. Although my kit is a currently purchased one, I am using some of the old style parts when the result is proven to be better. I just finished a set of old style bellcranks for my project a couple of days ago.
 
I only have the preview plans. They show the aileron bellcrank as being WD-421, apparently an RV-4 part.

Is there a part number for the older ones?

Dave
 
RV-3 Aileron Bellcrank (old style) P/N

These are "scratch" built from .063 2024-T3 Sheet and the callouts are as follows: 4ea - W-315A Aileron Bellcrank Plate, 4ea - 1/2x1 5/8 spacer strips, 2ea - AN218P4 (VA-146) Flange Bearing. After assembly these parts become W-315 Aileron Bellcrank. Hope this helps.
 
RV-3 Aileron Bellcrank

As dimensioned on drawing dated 1-10-84 serial 10342. It's basically a triangle with the legs 137 degrees apart. The control stick leg is 3 inches and the aileron leg is 3-3/8 inches from pivot point. (5-7/8 inches apart) The plates are assembled similarly to the elevator bellcrank.
 
Early RV-3 Ailerons

As dimensioned on drawing dated 1-10-84 serial 10342. It's basically a triangle with the legs 137 degrees apart. The control stick leg is 3 inches and the aileron leg is 3-3/8 inches from pivot point. (5-7/8 inches apart) The plates are assembled similarly to the elevator bellcrank.

I once owned an RV-3 that was built from the earliest set of plans (it was the 6th airplane completed) and the aileron up and down travel was virtually symmetrical (no differential), suggesting a bellcrank angle close to 90 degrees. I have no hard test data to compare, but the roll rate of that airplane was much higher than my later RV-3 built from the 1984 plans.

Before I decided to replace my old wing kit with new RV-3B wings for my current project, I had decided on fabricating a bellcrank set with 115 degree included angle, and will try to accommodate that in the new B wing structure.

I would be interested to know the particular angles used in the modified bellcranks referred to in the above messages, and if any flight test impressions have been gathered.
 
Update on aileron performance - a long read !

I built a -3 because many considered it the most fun to fly RV. I bought 3B wings from salvage. I complained here that stick force was disappointing compared to expectations from glowing pireps. Jim Winings said the ailerons were smashed too small on the trailing edge and several folks say the 3B bellcrank is not the same as the original 3.

So, I analyzed the kinematics of the 3B vs -3 bellcrank and the 3B IS disadvantaged regarding stick input force. Then I built two new ailerons to address the thin trailing edge issue. As many are aware, some aerobatic ships use thick trailing edges and some jets use nearly squared trailing edges.

I was very careful on the new ailerons to assure the skin entered the curved trailing edge radius harmoniously without bumps or undercuts. The end ribs supplied by Vans defined this geometry. I was surprised to find the resulting trailing edge radius was larger than the plans called for. A 1/4" dowell fits easily inside the skin at the trailing edge. It was theorized that bigger could be better, so they are on the airplane.

Ironflight suggested I update my VAF posting when I had results. RVbuilder2002 considered my findings logical with no misleading or unsafe conclusions, so here it is:
The reduction in stick force is DRAMATIC, to the extent you can roll the ship with index finger pressure. Hands off the stick is dead stable subject to normal trim (heavy wing) characteristics. RVbuilder 2002 advised that the thicker trailing edge is known to reduce stick force at the potential reduction in roll rate. OK, I won't compete with F22's.

The -3B can be disappointing and awesome. Pay close attention to ailerons. I hope this helps a VAF participant.
 
Larry,
I've been strongly disappointed by the control feel on my RV3. a HUGE thank you for the update, I am going to look into the trailing edge of mine and see if there is anything i can do about it.
 
I built a -3 because many considered it the most fun to fly RV. I bought 3B wings from salvage. I complained here that stick force was disappointing compared to expectations from glowing pireps. Jim Winings said the ailerons were smashed too small on the trailing edge and several folks say the 3B bellcrank is not the same as the original 3.

So, I analyzed the kinematics of the 3B vs -3 bellcrank and the 3B IS disadvantaged regarding stick input force. Then I built two new ailerons to address the thin trailing edge issue. As many are aware, some aerobatic ships use thick trailing edges and some jets use nearly squared trailing edges.

I was very careful on the new ailerons to assure the skin entered the curved trailing edge radius harmoniously without bumps or undercuts. The end ribs supplied by Vans defined this geometry. I was surprised to find the resulting trailing edge radius was larger than the plans called for. A 1/4" dowell fits easily inside the skin at the trailing edge. It was theorized that bigger could be better, so they are on the airplane.

Ironflight suggested I update my VAF posting when I had results. RVbuilder2002 considered my findings logical with no misleading or unsafe conclusions, so here it is:
The reduction in stick force is DRAMATIC, to the extent you can roll the ship with index finger pressure. Hands off the stick is dead stable subject to normal trim (heavy wing) characteristics. RVbuilder 2002 advised that the thicker trailing edge is known to reduce stick force at the potential reduction in roll rate. OK, I won't compete with F22's.

The -3B can be disappointing and awesome. Pay close attention to ailerons. I hope this helps a VAF participant.


Larry I have a RV7A built for me (here in Brazil it is legal).

I'm a bit disappointed with aileron input and control even compared with my former plane a RV9 that should roll much less than my new RV7A.

I do have aileron buffet in both sides when rolling, and I did have a heavy wing issue that was "fixed" by the builder.

I do not know I need to use rudder in rolls with the RV7 like I did not use rudder with my first plane that was a RV9. No buffets on the 9!

I'd really want to fix this roll rate (increase it) and stop the buffeting. Do you think I need more deflection on it? Maybe new ailerons (better shaped) also?

Can you contribute with any blue prints , plans , tips?

I very grateful any help I can get. I just think the way it is is not the way it was designed to be. Was an assembling error.
 
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