Aileron Pushrod length question

Desert Rat · #1 12-10-2019, 05:47 AM

On the old 2006 vintage wings I bought, the print says to cut the tube 65 25/32" The new preview plans I have call out a longer dimension, presumably to deal with the problem I've read about on here where people were finding them to be too short.

The callout on the new preview plans as pretty fuzzy and isn't any better on the electronic version, but I believe it says 66 26/32"

Can somebody verify that from a set of full sized new-ish plans? I get that the idea is to make it about an inch longer than it used to be, but it just seems weird that they would increase it by 1 1/32"

wirejock · #2 12-10-2019, 08:31 AM

65-25/32" on my plans. I cut them 3/8" longer. 66-5/32".

Desert Rat · #3 12-10-2019, 09:38 AM

Thats odd. These wings are from 2006 and the 15A print that came with them definitely shows the old 65 25/32 dimension.

However when I look at my new preview plans they show the bigger dimension, even though the title block shows that it hasn't had a revision since 2003.

I put a screen shot of the new callout in my build log.

https://eaabuilderslog.org/?blproject&proj=7WxtkKls2

Z-EDD · #4 12-10-2019, 10:46 PM

Quote:

Originally Posted by Desert Rat

On the old 2006 vintage wings I bought, the print says to cut the tube 65 25/32" The new preview plans I have call out a longer dimension, presumably to deal with the problem I've read about on here where people were finding them to be too short.

The callout on the new preview plans as pretty fuzzy and isn't any better on the electronic version, but I believe it says 66 26/32"

Can somebody verify that from a set of full sized new-ish plans? I get that the idea is to make it about an inch longer than it used to be, but it just seems weird that they would increase it by 1 1/32"

I don't think vans have changed this, I think your blurry copy of the plans actually reads 65 25/32. As you point out 1 1/32 is an odd increase, but it is also way too much to resolve the minor discrepancies that have been reported. Mine were slightly short at the dimension shown on the plans, but I was planning on adding around 1/4 to resolve this. 1 inch could almost make them too long. Another clue is that 26/32nds should resolve to 13/16ths. Don't think Vans would make this kind of error.

Desert Rat · #5 12-11-2019, 05:07 AM

Quote:

Originally Posted by Z-EDD

I don't think vans have changed this, I think your blurry copy of the plans actually reads 65 25/32. As you point out 1 1/32 is an odd increase, but it is also way too much to resolve the minor discrepancies that have been reported. Mine were slightly short at the dimension shown on the plans, but I was planning on adding around 1/4 to resolve this. 1 inch could almost make them too long. Another clue is that 26/32nds should resolve to 13/16ths. Don't think Vans would make this kind of error.

You may be right, but it sure looks like 66 26/32 doesn't it? As for that dimension making them too long, I suspect you're right.

I called builder support when they opened for business yesterday morning and they thought it looked like the bigger dimension on their end as well. Their suggestion was to measure the rod ends and then do the math to determine what tube length was actually needed to get to the overall dimension of 69 9/32. When I did that, I discovered that a 66 26/32 tube is would cause the rod ends to be bottomed out on the jamb nuts to achieve this, leaving me with the ability to adjust it longer, but not shorter. Who knows, maybe that's what they intended?

I need one of these tubes at least temporarily installed to check clearance for my pitot lines. I have a heated pitot with a min length requirement for the hard lines coming off of it and the previous owners of these wings cut the hole for the pitot mast 1 bay inbd of the bell crank. The skin is just clecoed on, so now is the time to change this if there's interference with the tube.

At this point I'm just going to finish one end so I can do a trial fit for clearance and leave them long with the cockpit side unfinished until I mate the wings on down the road and can determine a real world length.

CubedRoot · #6 10-03-2020, 11:30 AM

I’m about to cut my pushrods and was wanting to know if any of you guys had any issues with cutting longer?

Larry, did your dimensions work out ok?

wirejock · #7 10-03-2020, 02:09 PM

Quote:

Originally Posted by CubedRoot

I’m about to cut my pushrods and was wanting to know if any of you guys had any issues with cutting longer?

Larry, did your dimensions work out ok?

Sorry. They haven't been connected yet.

Desert Rat · #8 10-03-2020, 04:08 PM

I left them long with only one end done. Figured it really wouldn't be a problem to wait until the wings are on and then finish the other end.

Z-EDD · #9 10-04-2020, 03:05 AM

Quote:

Originally Posted by CubedRoot

I’m about to cut my pushrods and was wanting to know if any of you guys had any issues with cutting longer?

Larry, did your dimensions work out ok?

I decided to add 3/8s to my second set which worked out fine when I rigged everything last month. Sorry I don't have any photos and the plane is in the paint shop. Works out to 66 5/32nds for the tube length. Wonder if the 2 is a typo?

Another theory on this. Vans probably intended the VA-111 and tube to be drilled together at precisely minimum edge distance for the rivets. If a cautious builder were to add 1/16th extra edge margin to each part, at both ends, then the pushrod would end up 1/4 inch shorter than intended! I suspect that this is what happened to my first set of pushrods. Perhaps looking at the overall dimension would be the best way to go.

CubedRoot · #10 10-04-2020, 11:28 PM

Well gents, I made the leap and cut my tubes tonight. I used the bolt-in-the-bench method to figure out what length the tubes needed to be cut to assure the 69 9/32" total length from the rod end to rod end.

It appears that for my tubes, 66" of length, maybe 65 15/16", would be the ideal length. This let me thread my rod ends to the halfway point on their threads, AND gave me 1/4" of clearance for the rivets in the VA-111 end joint.

I detail it here on my blog post: https://theskunkwerx.com/rv7/aileron...-tubes-part-2/

Really happy with the way they came out for now. I hope that 69 9/32" is the exact length we need. I am only halfway on the threads on each heim joint / rod end so there should be plenty of adjustability.