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  #11  
Old 02-28-2014, 03:30 PM
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rvbuilder2002 rvbuilder2002 is offline
 
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I guess it warrants repeating regularly....

Even though all RV's have roots back to the RV-3, that doesn't mean the are all the same in all respects....

The thickness / cord ratios on the RV-10 and RV-9 rudder (and RV-7 as long as it was built with the riveted T.E. rudder), have flat sides and can be riveted with them weighted down flat to a work table.
All of the other tapered profile control surfaces (elevators included) are not entirely flat on the skin surfaces and can not be weighted flat while riveting.
That is why the "V" blocks previously mentioned have been supplied in the RV-6, 7 and 8 emp kits.
The rudder on the RV-14 also falls into this category, though V blocks are not used because the trailing edge needs to be back riveted on a back rivet plate.

The build instructions for the RV-14 rudder do not say to weight it down flat, but it looks like some additional information will need to be added. I will look into it.
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  #12  
Old 02-28-2014, 04:05 PM
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ppilotmike ppilotmike is offline
 
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Quote:
Originally Posted by rvbuilder2002 View Post
I guess it warrants repeating regularly....

Even though all RV's have roots back to the RV-3, that doesn't mean the are all the same in all respects....

The thickness / cord ratios on the RV-10 and RV-9 rudder (and RV-7 as long as it was built with the riveted T.E. rudder), have flat sides and can be riveted with them weighted down flat to a work table.
All of the other tapered profile control surfaces (elevators included) are not entirely flat on the skin surfaces and can not be weighted flat while riveting.
That is why the "V" blocks previously mentioned have been supplied in the RV-6, 7 and 8 emp kits.
The rudder on the RV-14 also falls into this category, though V blocks are not used because the trailing edge needs to be back riveted on a back rivet plate.

The build instructions for the RV-14 rudder do not say to weight it down flat, but it looks like some additional information will need to be added. I will look into it.
Sorry, I thought the 10 rudder was similar to the 14. While I saw the 14 in person at OSH, I was so busy oohing and ahhing that I couldn't honestly tell you how that particular rudder goes together. Didn't mean to steer anybody wrong.
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  #13  
Old 02-28-2014, 05:43 PM
DaAV8R DaAV8R is offline
 
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Quote:
Originally Posted by ppilotmike View Post
Sorry, I thought the 10 rudder was similar to the 14. While I saw the 14 in person at OSH, I was so busy oohing and ahhing that I couldn't honestly tell you how that particular rudder goes together. Didn't mean to steer anybody wrong.
Same here.

That was a nice narrative by Scott. He should really consider designing airplanes for a living
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  #14  
Old 02-28-2014, 11:19 PM
Greg Priest Greg Priest is offline
 
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I am building this RV-14 with Rocky005 who started this thread.
Scott thanks so much for commenting here, I am looking forward to following this thread to see how it pans out.

Quote:
Originally Posted by rvbuilder2002 View Post
I guess it warrants repeating regularly....
Even though all RV's have roots back to the RV-3, that doesn't mean the are all the same in all respects....
Agreed, they are not the same in all respects.

Quote:
Originally Posted by rvbuilder2002 View Post
The thickness / cord ratios on the RV-10 and RV-9 rudder (and RV-7 as long as it was built with the riveted T.E. rudder), have flat sides and can be riveted with them weighted down flat to a work table.
I don't understand how any of the afore mentioned models rudders can have flat sides and be weighted down as the rudders are not constant cord and instead the rudders are tapered at the leading edge but not tapered at the trailing edge (if that makes sense).

Quote:
Originally Posted by rvbuilder2002 View Post
All of the other tapered profile control surfaces (elevators included) are not entirely flat on the skin surfaces and can not be weighted flat while riveting.
That is why the "V" blocks previously mentioned have been supplied in the RV-6, 7 and 8 emp kits.
Sorry not sure what you mean here? The elevators are constant cord so they are flat (ie no twist). We are not planning on weighting them down flat but I believe we can assemble the elevators and ailerons on a flat surface?

Quote:
Originally Posted by rvbuilder2002 View Post
The rudder on the RV-14 also falls into this category, though V blocks are not used because the trailing edge needs to be back riveted on a back rivet plate.
My point is that I believe a change may be required to the build process as a jig is needed. One RV-7 builder has posted in this thread and has indicated that he also has a asymmetric rudder issue. It may simply be a cosmetic issue, we are waiting for VANS's to reply to a support email before we consider ordering a new rudder
Quote:
Originally Posted by rvbuilder2002 View Post
The build instructions for the RV-14 rudder do not say to weight it down flat, but it looks like some additional information will need to be added. I will look into it.
The trailing edge was not deliberately weighted down but we did attach a light weight aluminum right angled piece to ensure we obtained a straight trailing edge. This worked and our trailing edge is very straight.
In hind sight we needed to jig this right angled piece and lift one end by 10mm. That way the rudder would rock by 10mm on both sides (and be symmetrical).

VANs may want to consider moving to a constant cord on the Vertical Stabilizer and rudder on future models, it may not look as nice but it would be much easier to build.

Rocky005 will post some additional pictures to help clearly show our problem.
I was hoping other builders would check theirs rudders on a bench and post here as its not an obvious flaw and they may not have noticed.
Again your thoughts are appreciated.

Last edited by Greg Priest : 02-28-2014 at 11:25 PM.
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  #15  
Old 03-01-2014, 12:04 AM
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rvbuilder2002 rvbuilder2002 is offline
 
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It is possible for a rudder to have a flat side because it tappers in cord and in thickness. If the ratio of change of each is correct, it would allow the skin to be flat.
Try it with a couple pieces of cardboard cut to mimic miniature rudder skins... join them at the trailing edge and you will see that a spar of the proper taper ratios would make the skins each flat.


Constant cord elevators... I was talking about the other models... the RV-4,6, 7 and 8 all have tapered elevators. Only the 9,10 and 14 have constant cord ones.

BTW, I believe the construction manual does prescribe weighting down all the rest of the control surfaces to help assure they are built flat.

Proper alignment of the RV-14 rudder is almost automatic (as long as it isn't weighted down on a flat surface during riveting). All of the prototypes built so far were done so with no special effort for alignment other than to make sure teh T.E. remains straight.

It is possible to shim it a specific amount in a specific location to assure it is straight. That is what I will look into.

I don't think a change to constant cord is necessary. Almost 3000 RV-9's, RV-7's, and RV-10's (combined) have been successfully built with this style of rudder.

If the final decision is that the rudder is not acceptable, you could correct the one you have by just un-riveting the trailing edge and re-riveting with it correctly aligned. It requires just a very small amount of movement between the two skins to allow the amount of torsional twist you are measuring. This is well within the fit tolerance of the dimpled (thus slightly enlarged) holes. I am certain that re-riveting the T.E. would allow it to be properly aligned.
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Van's Aircraft Engineering Prototype Shop Manager
Hubbard, Oregon
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  #16  
Old 03-01-2014, 12:10 AM
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rvbuilder2002 rvbuilder2002 is offline
 
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Quote:
Originally Posted by ppilotmike View Post
Sorry, I thought the 10 rudder was similar to the 14.
No problem.
They actually are similar... structurally, but they are different dimensionally.
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Opinions, information and comments are my own unless stated otherwise. They do not necessarily represent the direction/opinions of my employer.

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Van's Aircraft Engineering Prototype Shop Manager
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  #17  
Old 03-01-2014, 08:54 AM
KHeidorn KHeidorn is offline
 
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I lost some sleep over this last night :-) . My rudder would rock a little while laying flat on one side but not the other. I couldn't wait to get to the shop to check it out.

I stood the rudder up on the bench, balancing on rudder horn, and put my digital level against trailing edge. Both sides were the same, vertical.

I am finding the empennage kit instructions not as well written or organized as the wing kit. In the rudder section the instructions refer you to section 5.7, folded trailing edges, we don' t have those. Section 5.8 says to use shims to keep rudder spar straight and to weight it down, but it is being suggested here to not weight the rudder while riveting.

I think my rudder turned out fine. Better lucky than good :-)
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  #18  
Old 03-01-2014, 10:40 AM
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rvbuilder2002 rvbuilder2002 is offline
 
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Quote:
Originally Posted by KHeidorn View Post
I lost some sleep over this last night :-) . My rudder would rock a little while laying flat on one side but not the other. I couldn't wait to get to the shop to check it out.

I stood the rudder up on the bench, balancing on rudder horn, and put my digital level against trailing edge. Both sides were the same, vertical.

I am finding the empennage kit instructions not as well written or organized as the wing kit. In the rudder section the instructions refer you to section 5.7, folded trailing edges, we don' t have those. Section 5.8 says to use shims to keep rudder spar straight and to weight it down, but it is being suggested here to not weight the rudder while riveting.

I think my rudder turned out fine. Better lucky than good :-)

That would be a good way to check for twist if you measure at the bottom rib and the top rib on both sides. If the opposing sides measure the same (top L & R, and bottom L & R), then you know it is straight.


Plans.... It is difficult to issue new release plans with absolutely zero errors. The first builders end up helping to scrub them out. If you were one of the later wing kits, you benefited from the earlier builders (attempts were made to issue corrections ASAP).
There have been very few errors mentioned so far in the emp/tail cone. Is that because few builders have gotten all the way through it? Possible.

What do you say builders? Have you found a lot of errors / issues in the emp/tail cone kit that you have not reported?
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Opinions, information and comments are my own unless stated otherwise. They do not necessarily represent the direction/opinions of my employer.

Scott McDaniels
Van's Aircraft Engineering Prototype Shop Manager
Hubbard, Oregon
RV-6A (aka "Junkyard Special ")
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  #19  
Old 03-01-2014, 11:03 AM
Qui Qui is offline
 
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As a first time builder of a RV, I guess I got lucky. I used the 3M tape and followed the plans as written. Rudder trailing edge is straight as an arrow and no twisting at all. I thought the tape was very easy to use.
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  #20  
Old 03-01-2014, 11:42 AM
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M McGraw M McGraw is offline
 
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Quote:
Originally Posted by rvbuilder2002 View Post
That would be a good way to check for twist if you measure at the bottom rib and the top rib on both sides. If the opposing sides measure the same (top L & R, and bottom L & R), then you know it is straight.


Plans.... It is difficult to issue new release plans with absolutely zero errors. The first builders end up helping to scrub them out. If you were one of the later wing kits, you benefited from the earlier builders (attempts were made to issue corrections ASAP).
There have been very few errors mentioned so far in the emp/tail cone. Is that because few builders have gotten all the way through it? Possible.

What do you say builders? Have you found a lot of errors / issues in the emp/tail cone kit that you have not reported?



A lot of errors/issues absolutely not! Some yes, but I know I could have not written a better manual. I'm a first time builder and very pleased with the quality of the kit and instructions. I have called Van's technical help about three times and quickly decided I should just read a little better before calling. With that said this website has been EXTREMELY helpful. While building the wing kit reading ahead to understand the manual was very helpful. The Tail kit has proven much more sequential. Most of the errors I have found have been on the order of wrong rivet callouts; however, as time has gone by I have gotten better at looking and thinking before riveting. Thank you to VAF and Vans, it is a fun way to spend the day.
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