RV-7 QB Flap Skin Width

I stared at this for over an hour going back and forth between the drawings, written directions and the actual left flap. Here's a photo. http://www.n212s.com/images/rv-7_qb_flaps.jpg

It looks like the inboard flap skin is way too long. The directions state some trimming will be needed when the wings are mated (doing that on Sat..... I hope) but this looks nothing like other flap photos I've seen around the web. These are QB flaps and supposed to be ready to go except for the hinges. I've started thinking they sent the wrong flaps. The right one is the same way. Not sure I could trim this back anyway. The final rib and rivet line seems too far inboard compared to other 7's I've seen.

Any input would be appreciated....

thx,

Chris....

trimming skin

I'm not there yet so I can't comment on correct length but I can tell you how to trim skin easiy in place. I used a laminate trimmer (small router) with a straight edge guide clamped to the surface and an Aluminum cutter bit (or a 2 flute straight carbide router bit). The bit is set down below the router base just enough to trim off the skin. This will have to be followed by a file or sandpaper to rinish the sharp edges. I used this method when trimming the horiz stab skin w/ the elevator in place. Worked great!

Chris,
I'm not at my hangar to look but it appears that the inboard edge of your flap extends too far. Dwg 14A shows the inboard rib set at an angle. In your picture the rivet line appears to be straight. You may in fact have the wrong flap possibly an 8?? because of the narrower fuselage. For reference, if you look at dwg 12 and place a straight edge on the furthest inboard corners of the tanks, main wing section and flaps they line up. Maybe try your thread in the general discussion area.

That's how I see it as well

Rockyjs,

Yeah, I noticed that too while staring at the drawings. I know some of the parts on the 7 and 8 are interchangeable. Some require slight modification to work (such as rear spar attach points). The flaps Vans sent do in fact have 7/7A-8/8A written on them with black marker pen. I'm not sure if the fuse width difference in the 7 and 8 is at issue here but it certainly could be.

I sent an email (with attached photos) to Van's support last night. Perhaps they can untangle this. It's always possible I'm missing something (done it before) but the angle on the inboard flap rib is rather telling.

Chris...

http://www.n212s.com
Wings\Fuse\Finish Kit ordered

Measured my QB flaps

My QB flaps also have 7/8 written on them. Measuring from the rivet line, I have 2 3/16" skin over hang on the hinge side and 1 1/8 by the trailing edge.

Rib angle?

EDIT: DUH! You caught the angle issue already. Oh well, I tried.

Something that strikes me odd about the picture is the angle of the inboard flap rib. The picture makes it look like the rib is aligned with the longitudal axis of the aircraft (vertical in the pic), but the inboard flap rib is supposed to angle inboard as it goes aft (see top right of DWG 14A). Perhaps it is just the picture.

Yes

Hi guys,
The extra length on the lower flap surface will cover the hole that the pushrod emerges from and tidy up the belly. The upper skin will be cut to a radius that matches the fuselage curvature as in the attached picture. You won't have much more than 1/2" of skin past the inner rib on top.

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Regards,

[Place witty title here]

Pierre,

That would mean much more than a trim on both flaps. There is quite a bit of skin material there that can be cut away however. The only mention in the plans is in the small bit of instructions on assembling the flaps. The comment is something like "material will have to be trimmed when hanging the wings but don't do that now". I had yellow highlighted a while back when I pre-read through the documentation. I guess there is no measurements Vans gives in advance as to making this cut? I couldn't find any. The builder must "wing it" as in "customize it to fit".

I still don't know what to think about the difference in the rib angle though between my flaps and the drawings. I will say this, in most cases when I've run into something like this with the kit design, after noodling on it for a while, it usually turns up I wasn't looking at it right and the kit was correct. I will probably proceed with the mating CAREFULLY this Sat. and see how it goes. I can always "bail-out" if I feel uncertain. And as usual, the second one is always better than the first.


Chris...

http://www.n212s.com
IO-360M1B, Dynon180
Garmin 496, DigiFlight II, SL-30
GTX-320

Measure this

Hi Chris,
Remember that you'll have close to 2" space between the inboard wing rib and the fuselage. The flap skin has to bridge this gap plus overlap the belly of the airplane and cover the pushrod hole. If you can measure the distance from the rear spar attach bracket on the wing, then measure how much further inboard the flap skin extends, I think you'll see where that extra skin will be. On my -6A I just measured around 2 1/2"-3" from the inboard edge of the wing to the underside flap skin. I'm assuming that you have the ailerons mounted so that the flaps are in the correct location?

Regards,

Yes, he can be taught!

Thanks Pierre,

Yeah, this is all starting to make more sense now. Van's responded a while ago and confirmed that "it's all good" as well. I wasn't thinking about how the bottom flap skin must "kiss" the belly of the bird, cover the push rod hole to reduce drag and all during normal flight. It's a little "nervey" figuring out how to cut this though. I guess I'll know more after the sweep and incidence are set and I hold the flaps up to take a look. (Oh yeah and the ailerons are mounted and look great. My local EAA Tech sponser came over last month and signed off on them.)

On a different note, I'll be needing transistion training at some point this fall. I may want to give you a shout. Thanks for your help.


Chris...

Chris,
Glad everything is OK! Where are you planning on flying that bird around Franklin? We almost moved there a few years ago, and I looked around for local airports.

[Witty title here]

Sure, around middle Tenn., Florida, Arkansas, Texas, Okla., New Mexico, Ariz., Utah, Color, Montana, Wyoming..... I have even been reading about these Bahama trips some of these groups are making. Once I get enough cockpit time I may be up for one of those too.

Since I live in the Nashville area my RV will turn a 7.5 hour drive to Destin into a 1hr 45 min. trip via air.


Too cool.....