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Rear Spar Trimming Required? RV7 QB Wings

T

Tedtheflyer

Member
Just curious.. I haven't seen any posts on this. The rear spar was not trimmed for the wing box on my 7 per DWG 38. Is it an oversight, or is this because the same wings are utilized for the 7 and 8? The 8 doesn't require trimming , so I figure they simply leave that task to the 7 builder. Whats been your experience with QB wings for the 7?
 
Drawing 38 detail

I had the same question for Van's.

The answer I got from them was kinda strange. The gist was that the detail in drawing 38 is full scale. So measure the drawing and then the rear spar and you will know if it has been trimmed already. My quickbuild wing had not been trimmed. I just was not expecting the drawing to be full scale. Many of Van's drawings are now that I'm clued to notice that detail.
 
The wings are used for both 7 and 8s. That piece does need to be trimmed. I actually needed to trim a little more off during wing fitup.

If you have access to a scanner or copier, make copies of the trim drawing and use as a template. Glue it on the spar and grind away.

Roberta
 
Thanks

Thanks to both of you for the sanity check.... There are no specific instructions for QB builders about this. It's a reminder to study the plans!!!!
Ted :)
 
Like Roberta, I too had to trim a tiny extra off of the rear spar end. There was an interference with a universal rivet head on the fuse. It caused a small amount of forward sweep of the wings that I was not appy with. (It seems to me that the rivet should have been a 426 instead.) My wings & fuse are QB's

Sam
 
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I too, saw that and was puzzled!

So the general concensus is to trim them at fitup?

I was initially going to trim them during assembly, but realized that it could be done more accurately later.

Does everyone concur?

:confused: CJ
 
Capt. John,

I think I would go ahead and trim the rear spar per the drawing first. If you try to do it all during the fitup you may be taking the main spar bolts in & out quiet a lot trying to get it "just right". I would try to minimize the number of times the bolts get reinserted into the spar holes.

....Let me edit this now that I've looked at your question again... :eek:
If you're doing the standard build wings, it may be easier to trim the spar before assembly...(and I'm just going by Checkoway's comments) It is really no problem to trim at time of fitup.

Sam
 
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ah man, why didn't I do a search first.(or almost as good read the plans and prints.) it's all coming back now.

got a royal butt kickin' trying to just get drift 7/16 bolts thru the spar and now i have 1/8 of forward sweep. now to try to get those bolts out. Let me guess; i'm supposed to loosen up on those spar bolts first?

also, wish I remembered what the back on the trim area tab looks like, it looks like I could get it in another 1/8" since I can visually see the taper.

a 2x4 and a hammer didn't seem to make any difference.
 
After checking sweep we realized the rivet at the top of the spar tab was causing interference to obtain the proper "0" sweep

at the leading edge of the wing. We were able to pull each wing out a bit so I could Dremel the top of the rear spar away in

order to clear the rivet head. After the wings are removed later I will clean this area up a bit. I also had to Dremel a bit away

just under the rivet to clear the skin. This is why I said up front it would have been great to cut the tab about 1/16" shorter

than the plans call for here.

WINGS%20228.jpg


Heres my install experience. http://www.jeffsrv-7a.com/WINGS/05-11-20.htm
 
thanks jeff

great picts jeff, just what i needed yesterday. Urggh.

interesting with that brasher head rivet, you're right plenty of room to get edge clearance without staying so close to it.

thanks again.
 
my final input-- like all of you said-- just follow the plans. I made a template off of dwg 38 detail F IIRC and cut another 1/16" off. as per suggested since there in plenty of material.

I STILL had to stick a piece of alum with sandpaper on it and grind a brasher head rivet a tiny bit to get it right. ( sure wasn't going to pull the wing again.)

I came to the conclusion that 3/32" of an inch more than the plans call for is just right.

Also, why in the world is that knotch in the front gas tank attach? It's making things harder, i could have just drilled a hole.

http://www.pbase.com/mark2nite/image/53905001/large
 
another thought

You don't want a metal to metal contact with the drag spar and the side of the fuselage. There will be a slight amount of movement from the aerodynamic forces back there.

If you're slow builder, do it while prepping stuff for construction. If quick build, take off the plans amount plus a 1/16" and you'll be fine. A lot of things on the plans are head scratchers, this isn't one of them and best to learn from the hundreds that have been there.

And I ask, Why hasn't Van's made a few key strokes in the CNC program and fixed this?????

Darwin N. Barrie
Chandler AZ
 
I did this (slo-build) before riveting the doublers together. The only problem with this is that DWG 38 doesn't come with the wing plans; it comes with the fuselage plans. So I had to dig out the preview plans and use the measurements indicated. Seemed pretty straightforward and with wing fitting not to far in the future, I'm kinda glad I did it then rather than look forward to a big trimming session (maybe just a little trimming session instead).
 
RV7Guy said:
And I ask, Why hasn't Van's made a few key strokes in the CNC program and fixed this?????

Darwin N. Barrie
Chandler AZ
Click to expand...

Simple-the rear spar is the RV-8 rear spar. (The -8 fuse tapers sooner than the -7) So rather than stock two parts, and to keep costs down, the builder makes the mod to make it work on the -7.
 
Makes sense!!!

wingtime said:
Simple-the rear spar is the RV-8 rear spar. (The -8 fuse tapers sooner than the -7) So rather than stock two parts, and to keep costs down, the builder makes the mod to make it work on the -7.
Click to expand...


Now I know!!!

Thanks,

Darwin
 
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