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03-13-2012, 02:53 PM
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Join Date: Jun 2006
Location: San Jose, CA
Posts: 1,125
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Flap to bottom of fuselage gap
OK, I've adjusted my ailerons then, I lined up my flaps to those. I installed wing tips and everything look peachy.
I look at the inboard side of the flaps and worse case, I see about a 3/4" gap between the flap skin and the bottom of the fuselage when the flaps are completely sucked up. The left side is a little less.
Then, I go to the airport to look at a friends RV-9A and he's got no gap!
So, I do a search and everybody says this gap varies a lot and it's not abnormal. I confirmed this with Van's. What I can't get my head wrapped around is how can there be so much variance here? The kit is prepunched. I doubt if the incidence varies much because you don't have much wiggle room when drilling the rear spar. Yea, I'm sure there is some sort of tolerance build up but I'm having a hard time buying that much build up.
Any ideas?
What kind of gaps are others seeing with the 9?
__________________
Kelly Johnson
San Jose, CA
RV-9A
Pink slip issued: 5/7/12
First flight: 5/28/12, Memorial Day.
Phase I Complete: 8/18/12!
2020 donation: complete
Last edited by ArVeeNiner : 03-13-2012 at 02:56 PM.
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03-13-2012, 03:28 PM
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Join Date: Oct 2008
Location: Lake Country, B.C. Canada
Posts: 2,416
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poll?
obviously I'm not laying under my plane, but I'm gonna say 1/4 to 3/8", pretty uniform side to side. I wonder how NO gap is achieved; would the flap motor like bottoming out like that?...or perhaps it's no different than full extension?
__________________
Perry Y.
RV-9a - SOLD!....
Lake Country, BC
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03-13-2012, 03:32 PM
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Join Date: Jan 2005
Posts: 3,646
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You might post a picture or two... but you've probably got a bit of warp in one of your flaps, Kelly. That is not at all unusual given the 8'+ length of them. It's pretty hard to build a perfectly flat flap. One of my flaps has about 1/4"-3/8" twist, making the flaps and ailerons not line up exactly when the flap is in the full up position (bottom skin of flap tucked up tightly to bottom of fuselage). Ken Scott indicated to me that this is common and that the plane probably won't notice it, but that only flight would tell. The only options are to either rebuild the flap or, at a minimum, try to separate the trailing edge of the flap and re-rivet. If you used proseal or some other adhesive on the trailing edge, however, the latter is probably not a good option.
__________________
Steve M.
Ellensburg WA
RV-9 Flying, 0-320, Catto
Donation reminder: Jan. 2021
Last edited by alpinelakespilot2000 : 03-13-2012 at 03:36 PM.
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03-13-2012, 05:00 PM
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Join Date: Jun 2006
Location: San Jose, CA
Posts: 1,125
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Quote:
Originally Posted by alpinelakespilot2000
You might post a picture or two... but you've probably got a bit of warp in one of your flaps, Kelly. That is not at all unusual given the 8'+ length of them. It's pretty hard to build a perfectly flat flap. One of my flaps has about 1/4"-3/8" twist, making the flaps and ailerons not line up exactly when the flap is in the full up position (bottom skin of flap tucked up tightly to bottom of fuselage). Ken Scott indicated to me that this is common and that the plane probably won't notice it, but that only flight would tell. The only options are to either rebuild the flap or, at a minimum, try to separate the trailing edge of the flap and re-rivet. If you used proseal or some other adhesive on the trailing edge, however, the latter is probably not a good option.
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Nope, flaps are straight. I remember marvelling at how straight they came out. Of course, I haven't checked them since they've been installed. I'll do that.
I'll post some pictures.
__________________
Kelly Johnson
San Jose, CA
RV-9A
Pink slip issued: 5/7/12
First flight: 5/28/12, Memorial Day.
Phase I Complete: 8/18/12!
2020 donation: complete
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03-13-2012, 05:09 PM
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Join Date: Jan 2005
Posts: 3,646
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Quote:
Originally Posted by ArVeeNiner
Nope, flaps are straight. I remember marvelling at how straight they came out.
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Well, if so, cross my explanation off the list. However, remember that a control surface can be perfectly straight (have no wave) in its trailing edge and yet be warped, or have twist. Initially, I thought mine turned out perfectly as well b/c the trailing edge was straight as an arrow. The problem was that the trailing edge and rest of the flap, both straight, were going different directions. The best test is to lay the flap down (upside down) on a known perfectly flat surface and see if either the inboard or outboard side of the trailing edge sticks up a bit from the flat surface. Anyway, good luck with your investigations.
__________________
Steve M.
Ellensburg WA
RV-9 Flying, 0-320, Catto
Donation reminder: Jan. 2021
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03-13-2012, 08:37 PM
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Join Date: Aug 2005
Location: Abilene, Texas
Posts: 64
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I had so much difference in that gap that I had to cut one of those overlapping flap skins off to get full retraction on the left. I perseverated over this, but ultimately, I saw no other option. My plane flies straight as an arrow-it just looks a little catawhompy if you crawl underneath.
Steve Johnson
RV-9A, 175 hours
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03-13-2012, 09:29 PM
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Join Date: Apr 2007
Location: Cedar Hill, Tx.
Posts: 159
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The gap
Even though every thing is pre punched there is still "slop" in the way things fit. Our RV 7 came out the same way. If you were able to mount the wings in the exact position they are suppose to be in permanently (the angle of incidence) then rivet the flap hinges it would have come out flush with the bottom of the wing.
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member 1 of 6
Metal Feathers Club
RV 7 N706CB
1st flight Oct 18, 08
S/N 72847 tip 200HP CS glass IFR
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03-13-2012, 11:01 PM
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Join Date: Nov 2005
Location: AUSTRALIA
Posts: 749
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IMHO even with a pre-punched kit it is possible to build a twist in the wing, the flap and the aileron and all could conspire to cause a gap between the lower flap surface and the fuselage. See this thread post #21 for my further comments.
Fin
9A
Last edited by Finley Atherton : 03-13-2012 at 11:05 PM.
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03-13-2012, 11:03 PM
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Join Date: Jun 2006
Location: San Jose, CA
Posts: 1,125
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I got another data point tonight after our EAA meeting. I looked at another 9 and he had the same issue. He just bent up the inboard end of the flap which closed the gap. Weird. I'm sure it will fly just fine!
Steve, I'm am curious though if my perfectly straight flap is really straight. I'll put a straight edge on it the next time I'm out there.
Thanks guys!
__________________
Kelly Johnson
San Jose, CA
RV-9A
Pink slip issued: 5/7/12
First flight: 5/28/12, Memorial Day.
Phase I Complete: 8/18/12!
2020 donation: complete
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03-14-2012, 05:16 AM
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Join Date: Jan 2005
Location: Louisville, Ga
Posts: 7,840
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Nope.
Kelly, the way to check for warpage is NOT with a straight edge.
Back away from the airplane/flap and sit down, looking at the trailing edge of the flap from a few feet away.
Position yourself vertically, until there is as much flap above the trailing edge as below it. If it's warped, it will be evident.
Best,
__________________
Pierre Smith
RV-10, 510 TT
RV6A (Sojourner) 180 HP, Catto 3 Bl (502Hrs), gone...and already missed
Air Tractor AT 502B PT 6-15 Sold
Air Tractor 402 PT-6-20 Sold
EAA Flight Advisor/CFI/Tech Counselor
Louisville, Ga
It's never skill or craftsmanship that completes airplanes, it's the will to do so,
Patrick Kenny, EAA 275132
Dues gladly paid!
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