Elevator Trim Servo Mounting

Wilkie · #1 05-12-2006, 07:51 AM

Hi Gang,

I'm building the -7 and have a quick question about mounting the electric trim servo in the elevator.

I was preparing to mount the servo and "Z" brackets onto the E-616PP Trim Cover Plate but if I follow the measurements given on drawing #4, the jackscrew of the servo does not line up with the slot in the E-616.

Which is more important, the measurements given on drawing #4, or having the jackscrew line up with the slot in E-616? Common sense tells me that it is more important to have the jackscrew line up with the slot but I just thought I'd ask the masses first.

thanks......
Scott

Guy Prevost · #2 05-12-2006, 08:01 AM

FWIW, I centered mine in the slot. If I recall correctly, I moved it about 3/32" closer to the edge of the access cover than was indicated in the plans. My elevators and trim tab are complete and I'm convinced I made the right choice.

Wilkie · #3 05-12-2006, 08:29 AM

Thank you Guy,

I estimated that my servo was misaligned by about 1/8" inch. That relates closely to your 3/32". I feel much better now.

Scott....

alpinelakespilot2000 · #4 05-12-2006, 09:11 AM

This is a common question that I've seen and was true with my 9 back when I was originally planning electric trim. Either ignore the measurements and center it or file the slot to make it a little wider if the pushrod rubs. Good luck.

Wilkie · #5 05-12-2006, 11:14 AM

Thanks again for the replies. I opted to ignore the measurements given on drawing #4 (RV-7) and just center the jackscrew in the slot in part #E-616PP.

I'm still pretty new to this whole airplane building thing and it seems like everywhere you read, they say to measure twice and cut once. But in some cases, such as this, I am to ignore the measurements and "make it fit".

Why can't Van's just say "center the jackscrew in the slot"? Instead, they give you dimensions that apparently aren't right.

Ok- ok, rant mode off! I'm gonna go back out to the garage and keep building!

Scott

rv8ch · #6 05-12-2006, 11:57 AM

Quote:

Originally Posted by Wilkie

I'm still pretty new to this whole airplane building thing and it seems like everywhere you read, they say to measure twice and cut once. But in some cases, such as this, I am to ignore the measurements and "make it fit".

Why can't Van's just say "center the jackscrew in the slot"? Instead, they give you dimensions that apparently aren't right.

Ok- ok, rant mode off! I'm gonna go back out to the garage and keep building!

This is good training for the rest of the kit. The instruction detail quickly tapers off as you progress in the kit. You'll be expected to figure it out. I'm the type that usually agonizes over every detail for extreme periods of time, and often end up doing whatever it was twice anyway. Don't worry about it - it's part of the experience. As the Van's guys are known to say "build on".

jcoloccia · #7 05-12-2006, 12:45 PM

Quote:

Originally Posted by Wilkie

Why can't Van's just say "center the jackscrew in the slot"? Instead, they give you dimensions that apparently aren't right.

It actually get better later on in the kit. Here's what happens:

Vans starts by holding your hand - drill this hole, drill that hole, debur this, mark that etc etc. The instructions are quite good.

By the time you get to the wing, it turns into stuff like "Rivet the ribs to the spar" and you need to figure out to deburr, prime, which holes get rivetted now and which don't. This is just fine by me.

Somewhere in the middle, right about the time you get to the rudder, the instructions become difficult to follow. In some spots they'll tell you to debur and dimple (for example) and in other spots they don't. This leaves you scratching your head... "Am I not doing this step for a reason that will become obvious later on, or did they just leave it out??". This thing to do is go through the directions step by step and just use it as a guide....then throw them out and use the plans and common sense to actually build the thing or you'll drive yourself nuts.

Specifically re: the jackscrew thingy. I had a similar problem. The solution was to pay attention to which side of the alignment marks I'm aligning things to. Even the thinner sharpies can spread out a bit and make a significantly thick line sometimes.

avq · #8 10-20-2010, 11:26 AM

So I had to build a new E-616PP trim cover plate because I did not align the brackets properly. Now I know why vans sends some "extra" aluminum with the kit

I originally dimpled holes for the E-616PP mounting screws but this deformed the cover plate rather badly. Before I do the same on the second one I would like to know how everyone else dealt with this.

Anton

airguy · #9 10-21-2010, 07:32 AM

I don't recall offhand the thickness of that plate, but if it's .032 or better you can countersink it instead of dimpling, to avoid the distortion. I have successfully dimpled .040 a few times, but it gets a little dicey and distortion of the part is much more common. Anything .040 or above really should be countersunk.

Hubitom1 · #10 10-21-2010, 07:47 AM

I ran into a similar problem, but this one was about the trim tab. The plans call for 1/4" from outside piano hinge to the center of the rivet hole. I followed it, having that nagging thought in the back of my mind that 1/4" times 2 should equal something around 1/2 an inch. Funny thing is that the hinge body is only 3/8" wide!!! Off course I then realized (too late) that my trim is now offset by exactly 1/8 of an inch. I don't think that I will lose too much sleep over it, but it's just another example of looking and thinking first before one does something.

Thomas