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Elevator counterbalance clearance with HS

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alpinelakespilot2000

Well Known Member
I'm fitting my elevators to the HS and am wondering if anyone else raises an eyebrow at the minimal 3/32" clearance between the counterbalance arms and the HS. The gap is consistent all the way up on both sides, so I'm assuming this is designed that way (and that I've built them straight). What makes this even more strange, if I remember correctly, even the trim tab specifies more clearance from the elevator.

Is anyone else concerned about the potential for something jambing up the elevators. Obviously it must not be that big of a deal, it just seems like the gap would be greater.
 
Good

Hi Steve,
I spoke with a guy in California who purposely closed all gaps, aileron to flap/wingtip and elevator counterbalance to Hs to 1/16" for drag reduction. Since you're using no-slop ball ends for hinges, I don't see how they could interfere at 3/32". YMMV,
Regards,
 
Stay out of icing conditions.

jedimike007 said:
What about ice buildup? Just a thought

Mike
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If you build of ice enough to interfear at that point your in big trouble with this plane.

Kent
 
Here is a test that my inspector did to my plane.

Standing next to the HS he pushed inboard on the elevator counter balance with about 50 lb of force and then moved it up and down. One rubbed just a little bit and I had to file down more clearance.

Kent
 
And I epoxy potted (with flox) the bolts and nuts that hold the lead weight on the counterbalance. Those things aren't going to come loose without heavy machinery.
 
Several people out here have been hammering down the weights prior to trimming so that they are flush with the rest of the rib. Gets the job done, but the holes will migrate outward slightly due to the flow of metal.

Curious: are there known cases of these things coming loose? I have heard about people epoxying these guys in over the bolts, but am wondering if it's just a superstition. You are going to be one unhappy camper if you need to remove them for some reason (though I can't think of a reason why)
 
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A quick check for clearance is to pull a quarter out of your pocket; It should drop down between (fall through) the elevator and HS for minimum clearance (bigger is OK) ;) Rosie
 
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Rosie said:
A quick check for clearance is to pull a quarter out of your pocket; It should drop down between (fall through) the elevator and HS for sufficient clearance ;) Rosie
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I doubt Van's would agree, they claim they want 1/8". That looked a bit large to me, but a quarter sounds pretty small...what is that, like <1/16"? The curvature (or not) of your end caps will come into play as well.
 
Think ice accumulation. I'm not sure how the ice forms back there, but I figure more gap is better -- within reason of course.

Sometimes we get caught up in "gap minimization" for the aesthetics of it, but in some cases more is better (i.e. flaps to ailerons to wingtip clearance, spinner to prop clearance, etc.). If you're racing at Reno, disregard...
 
later -9 kits different?

I looked at the gap between my HS and elevator counterweight arms last night. The gap is smaller at the TE than at the LE. I first thought that I had mounted the elevators poorly (with the inboard hinges adjusted too short) but I spent the greater part of a day doing it. I rechecked it yesterday, and all the measurements are dead on, including the distance between the elevator front spars and the HS rear spars.

I spoke to another builder who said that he was told that Vans had made a slight design change to the elevators to cause the counterbalance arms to extend outward at the front, supposedly to solve the clearance issue. It's pretty minor - you'd have to look for it, but the other builder didn't like the aesthetics much. Not sure if this is true, but it sure seems to be for my kit.

The counterweights extend beyond the skin as discussed in this thread, but with the angle of the arms, it will be no problem.
 
Paul Eastham said:
I doubt Van's would agree, they claim they want 1/8". That looked a bit large to me, but a quarter sounds pretty small...what is that, like <1/16"? The curvature (or not) of your end caps will come into play as well.
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Paul-
I couldn't find anything in the manual or drawings giving a gap distance and I remember a long time ago (1.5 years ago) asking Gus at Van's who said he wasn't aware of a specified gap. Do you know where you came up with the 1/8"? Just curious.
 
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alpinelakespilot2000 said:
Paul-
I couldn't find anything in the manual or drawings giving a gap distance and I remember a long time ago (1.5 years ago) asking Gus at Van's who said he wasn't aware of a specified gap. Do you know where you came up with the 1/8"? Just curious.
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Yes, I didn't see anything in the manual either, so I asked Van's. They replied with 1/8". At least one other builder I know has also asked and got the same response.
 
Thanks Paul. Once I finally get the counterweights installed I may take a file to the counterbalance skin and/or HS skin and make sure I have at least 1/8" as well. I'm pretty close to that now so it shouldn't take much.
 
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