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Elevator deflection callout

LettersFromFlyoverCountry

LettersFromFlyoverCountry

Well Known Member
Sorry to bother folks. Can someone point me to the plans # for an RV7A where it indicates the degrees up/down of deflection. I looked through the plans today as I'm trying to get the emp mounted for good and I swear, if I spend any more time sitting at these plans looking for some of these things (and not finding it), I'm never going to fly.
 
Super, thanks. The manual. Ah, I've totally forgotten how to use it; I've gotten so use to just looking at the plans.

BTW, I gave myself a scare over the weekend when I measured the UP deflection just by slapping a digital level on there. 16 degrees. Whaaaaa? i'M pretty sure it was s'posed to be more than that.

Then I read an old thread here that that's not the way to calculate it.

The problem with a long build is sometimes you don't remember what you were doing when you first installed a part.
 
Following up here. I actually have a slight difference in the elevator deflection from side to side. The elevators themselves are in trail and the trailing edges are level. I'm sure I have a slight twist in the HS (which I think I knew about a couple of years ago). The total deflection up, however, is about the same on both sides (off by about a half-degree).

And the down deflection is about the same, too, but it's 26 degrees and the callout on 15-2 says max 25.

As I understand it, the rudder stop for the down deflection is that T-shaped angle you build when you're building the aft fuselage, only you don't know it's the the down stop when you're building it and riveting in place (at least I didn't).

So what are my options here to bring that down deflection below 25 degrees? Drill that thing out of there and replace it?
 
Bob,

First, let's make sure that I properly understand the situation. I'm assuming that you have the elevators connected to the elevator pushrod, so they are effectively moving as a single unit. Thus the total angular movement from full down to full up is the same on each side.

You say that the up deflection differs a bit from side to side, and that you might have some HS twist. I interpret this as saying that if you put one elevator in trail with that side of the HS, you get a different amount of angular displacement to full up than you get on the other side. The difference in up travel is because you have a different starting neutral position on each side, due to HS and/or elevator twist.

Assuming all the above is true:

I would average the results from the left and right sides and see how it is. If it is inside the recommended limits, put away the digital level, and never check it again.

If the down travel is a bit more than the recommended max, personally I wouldn't worry about it. I can't see how that will get into any trouble.

If up travel is a bit more than the recommended limit, I would investigate how to reduce it. Too much up elevator could contribute to a too high AOA condition someday, so it is probably something to be avoided.

If either up or down travel is less than the recommended minimum, then you should do whatever is required to fix it.
 
don't worry about a little too much deflection

Its pretty darn rare that anyone ever feels that they have too much control authority. I have 31 up, 24 down.
 
Kevin Horton said:
You say that the up deflection differs a bit from side to side, and that you might have some HS twist. I interpret this as saying that if you put one elevator in trail with that side of the HS, you get a different amount of angular displacement to full up than you get on the other side. The difference in up travel is because you have a different starting neutral position on each side, due to HS and/or elevator twist.
Click to expand...

You have it pretty much right. I think I found that the down deflection on the left was 26.7 and on the right was about 25.9. Something like that (it was last night and my brain does a complete data dump after 24 hours these days). So average about 26.4...or about 1.4 more than the callout in the instructions.

The UP deflection is fine... I think the max is 30 degrees and I get an average of about 27.
 
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