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Rudder counter weight vs Tail Strobe

mfleming

Well Known Member
Patron
Lots of talk recently about Vne and big vs small rudders on a -7/A But my question is a bit more general.

From reading posts directly from Vans, their rudders are not to be statically balanced. Add the counter weight per the plans and you are good to go. This, of course is different than the elevators, which need balancing.

So if the rudder is properly weighted with the factory supplied counter balance. What happen when we add a tail strobe?

Common sense says add the weight of the tail strobe to the counter weight and one would be back to the factory spec, counter balance weight wise. But in aviation, sometimes relying on common sense can lead you astray.

Van's is closed until Monday (obviously) so we can't ask them. Searching VAF brought up a few discussions related to this but nothing I found addressed it directly.

What's peoples thoughts on this? Ever had this discussion with Vans? IS a tail strobe a bad idea, flutter margin wise?
 
Last edited:
Lots of talk recently about Vne and big vs small rudders on a -7/A But my question is a bit more general.

From reading posts directly from Vans, their rudders are not to be balanced. Add the counter weight per the plans and you are good to go. This, of course is different than the elevators, which need balancing.

So if the rudder is properly weighted with the factory supplied counter balance. What happen when we add a tail strobe?

Common sense says add the weight of the tail strobe to the counter weight and one would be back to the factory spec, counter balance weight wise. But in aviation, sometimes relying on common sense can lead you astray.

Van's is closed until Monday (obviously) so we can't ask them. Searching VAF brought up a few discussions related to this but nothing I found addressed it directly.

What's peoples thoughts on this? Ever had this discussion with Vans? IS a tail strobe a bad idea, flutter margin wise?

Look at the VANS supplied lower rudder fairing which has a lamp flange formed in it. Check the VANS build manual for any instruction to modify the counter weight with or without a lamp. If they had any concern about this, VANS would have covered it off with a plain fairing & appropriate instruction concerning the option.
 
Look at the VANS supplied lower rudder fairing which has a lamp flange formed in it. Check the VANS build manual for any instruction to modify the counter weight with or without a lamp. If they had any concern about this, VANS would have covered it off with a plain fairing & appropriate instruction concerning the option.

+1

They built you a part to hold a lamp, so seems VERY improbable that they did not consider the potential variances from no lamp to a heavy lamp and all in between. There is often more margin than you would expect. On the 10 elevators, they give you a stock weight and this covers from no paint all the way up to moderate paint. They do caution not to go too heavy on the paint though.

Larry
 
SNIP
From reading posts directly from Vans, their rudders are not to be balanced. Add the counter weight per the plans and you are good to go. This, of course is different than the elevators, which need balancing.

So if the rudder is properly weighted with the factory supplied counter balance. What happen when we add a tail strobe?

Common sense says add the weight of the tail strobe to the counter weight and one would be back to the factory spec, counter balance weight wise. But in aviation, sometimes relying on common sense can lead you astray.

Being counterbalanced for flutter does not equate to static balance along the hinge line. Same applies to things like RV-10 elevators that do come with enough lead to statically balance them. On my first RV-10 build I got "educated" by the good folks at Van's when I called them to tell them they made an error on the elevator balance...

Build on.
Carl
 
Being counterbalanced for flutter does not equate to static balance along the hinge line. Same applies to things like RV-10 elevators that do come with enough lead to statically balance them. On my first RV-10 build I got "educated" by the good folks at Van's when I called them to tell them they made an error on the elevator balance...

Build on.
Carl

Yes, I agree, statically balanced. Edited my original post to clarify that point.

Apparently on the -10 there are some parameters on rudder construction concerning extra paint / tail strobe etc.. My original post was in the vein of the rudder separation issues with the -7/A. So I think it’s reasonable to explore this issue.
 
Rudder

I suspect they performed the usual analysis taking into account the beacon in the cap. Since the lights are getting smaller and lighter, I like to think we (7 builders) are in good shape. What do I know?
 
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