Rudder counterweight

BruceMe · #1 09-20-2016, 05:24 AM

Should the counterweights on the rudder balance it at the hing? I pulled the weights from the old (bent) elevator and it's not even close. I can pull the other elevators weights and re-cast to shape. Shouldn't it balance like the elevators do? Or is close good enough?

This is a replacement rudder. The plans I have are older and illustrate the RV-3/4-style rudder w/o counter balance. So I don't know if there's a weight called out or technique. I searched VAF and the only posts I saw went unanswered. Help a builder out?

Thanks!

BruceMe · #2 09-20-2016, 06:53 AM

FYI... there are many rudders. Mine is perhaps a bit unusual. It's the origonal v1 counterweighted rudder for the RV-7/8. It does not use E-614-020 and the cavity it sits in does not exist. It's just a flat sheet extension.

It does not look like this...

https://www.vansaircraft.com/pdf/rev...14/RV-14_7.pdf

If I could find a picture of what it looked like I'd post it, but I can't. I will take one later.

vfrazier · #3 09-23-2016, 08:33 AM

Bruce, I'm a bit confused by your post. What model RV ?

Regardless, a LOT of Harmon Rockets are flying up to their 275mph redline with RV-4 tails and no rudder balance weights at all.

If your rudder doesn't have the weights, don't sweat it. At RV speeds you're unlikely to really need the extra weight for a multitude of reasons.

Carl Froehlich · #4 09-23-2016, 09:39 AM

Quote:

Originally Posted by BruceMe

Should the counterweights on the rudder balance it at the hing? I pulled the weights from the old (bent) elevator and it's not even close. I can pull the other elevators weights and re-cast to shape. Shouldn't it balance like the elevators do? Or is close good enough?

This is a replacement rudder. The plans I have are older and illustrate the RV-3/4-style rudder w/o counter balance. So I don't know if there's a weight called out or technique. I searched VAF and the only posts I saw went unanswered. Help a builder out?

Thanks!

As with the elevators, the weights are there for flutter, not to achieve a balance. For the RV-10 as example, the weights are no where near big enough to balance the elevators. Calling Van's on this I got the education.

So - build per plans and you are good.

Carl

BruceMe · #5 09-23-2016, 07:44 PM

Yeah... it's an older RV-6, but you can mount just about any tail you want except maybe the 3 & 10. It's wacky. What was on it was not counterbalanced. What I got to replaced the bent one is.. That is my dilemma. I have no instructions on how to install the counterweight, but I think I got it figured out. It's all done now, once I take pictures I'll post to my blog this weekend.

rockwoodrv9 · #6 09-23-2016, 07:53 PM

Bruce, will drawings for the 9 help? Let me know and I can send them to you.

BruceMe · #7 09-24-2016, 05:22 AM

I always appreciate the help. I think I got it figured out in the end, it's bolted on now.

Robert Anglin · #8 09-24-2016, 07:14 AM

We went through the same question while putting together the rudder and testing the balance. A call to Van's at the time got a simple answer. The rudder dose not get a balance it is simply built to plans with the weight provided was the answer we got at the time. I do not know if there is an optimum set point at where one could balance from the hinge point. But I would guess that has a lot to do with what air speeds you are pulling the tail at. You got it going in a good direction, keep it up you will get there. Yours, R.E.A. III #80888

F1Boss · #9 09-24-2016, 10:03 AM

Rudders (if counterbalanced) use about 60% balance as a starting point vs 100% for the elevs; flight testing will prove or disprove the balance percentage - changes may be required. This 60% starting percentage a TLAR number - your mileage may vary in either direction! If you add an elec trim tab to a rudder that does not normally have such, or your paint is abnormally thick, you should check the balance - otherwise follow the plans and you should be good to go.

The above is safe bet only if you observe the Vne as provided by the kit or aircraft manufacturer. Accelerating past the recommended Vne makes you a Test Pilot...best to do that sort of flying solo BTW.

Carry on!
Mark

lr172 · #10 09-24-2016, 11:04 AM

The original 6 rudder had no weight. Around 2000 they started using the 8 rudder, I believe. That rudder has a counterweight and it is engineered in weight/location and does not get balanced at installation, like the elevator, which is designed to be neutral and therefore requires balancing to match the installation. This is what I was told by Van's during my build.

Larry