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  #21  
Old 08-21-2018, 05:00 PM
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dave4754 dave4754 is offline
 
Join Date: Oct 2009
Location: Edson, Alberta, Canada
Posts: 466
Default Such things are a blessing!

Great news on your wife and being able to continue the build with her!
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Dave Cobb
[color="Red"]=VAF=2019 Donation - and a bit extra for great work![/COLOR="blue"]
Empennage RV 7 - Tipper
Wings complete

Dynon installed and running
Fuse closer to completion, Canopy complete
AME reviewed and repaired O-320-Lyc installed
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  #22  
Old 08-21-2018, 06:04 PM
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rmartingt rmartingt is offline
 
Join Date: Nov 2006
Location: Savannah, GA
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Thanks everyone! Things are progressing nicely and the fuselage is now ready to flip. I just need a cradle to set it in... so I'll work on drawing that up and work on fabricating it this week.

Now if we could only beat some sense into the insurance company so they'll stop dithering and pay the rest of the bills...
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  #23  
Old 09-11-2018, 07:13 AM
glockjacket glockjacket is offline
 
Join Date: Sep 2018
Location: El Paso, TX
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go tech!

Great looking future airplane!
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  #24  
Old 11-20-2018, 12:28 PM
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rmartingt rmartingt is offline
 
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Location: Savannah, GA
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Got some coworkers over with promises of beer, and we mounted the wings last week.

Today I checked rigging.

Incidence is a hair high (bubble is touching the forward mark) but it's even on both sides, all the way out (no twist).

Edge distances are good.

Triangulation is dead on to 1/32".

Both wings are swept forward 3/8" at the tip.

The flaps touch the bottom skin perfectly.

Close enough for government work!

Now there's a couple days' break for Thanksgiving and for my aft bolt drilling tools to arrive. Going to crack a cold one...


(And yes, that's our old stove back there... perfect for baking parts post-painting...)
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There are two kinds of fool in the world. The first says "this is old, and therefore good"; the second says "this is new, and therefore better".
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  #25  
Old 11-21-2018, 07:58 AM
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Bill Boyd Bill Boyd is offline
 
Join Date: Sep 2006
Location: Landing field "12VA"
Posts: 1,363
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You do realize with those forward-swept wings you're going to need a fly-by-wire control system to keep that twitchy airframe from departing straight-and-level, right?

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RV-6A - N30YD - flying since '98
RV-10 - N130YD reserved - under construction

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  #26  
Old 11-21-2018, 12:51 PM
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swisseagle swisseagle is offline
 
Join Date: Feb 2005
Location: 20km outside of Zurich, Switzerland
Posts: 440
Default Forward swept wings ... need to trim the rear spar.

Hello

I had also forward swept wings, but not that much.

Mostly it comes from the rear spar, that is not trimmed enough like it is in the plans. The spar is touching the fuselage side skin. This pushes the wing forward.

Maybe you want to check the rear spar and fix it before you build on.
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RV-7A, TMX-IO-320, FM-150, Sensenich FP
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  #27  
Old 11-21-2018, 02:28 PM
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rmartingt rmartingt is offline
 
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Quote:
Originally Posted by swisseagle View Post
Hello

I had also forward swept wings, but not that much.

Mostly it comes from the rear spar, that is not trimmed enough like it is in the plans. The spar is touching the fuselage side skin. This pushes the wing forward.

Maybe you want to check the rear spar and fix it before you build on.
The tolerance for sweep per the Mothership is 1/2in. I'm within tolerance, so I'm not going through this exercise again. Tolerances exist for a reason.
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  #28  
Old 11-22-2018, 04:15 AM
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rmartingt rmartingt is offline
 
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Quote:
Originally Posted by Bill Boyd View Post
You do realize with those forward-swept wings you're going to need a fly-by-wire control system to keep that twitchy airframe from departing straight-and-level, right?

Well, technically forward-swept wings donít automatically make for an unstable airframe, from the pilot-controllability standpoint at least. Thatís a function of change in pitching moment with respect to change in AOA and all that. The Hansa Jet had mild forward sweep, and (as far as I can tell) had conventional natural stability characteristics.

Now, forward-swept wings typically are unstable aeroelastically and are much more prone to a phenomenon known as ďdivergenceĒ. Essentially, as the wing generates more lift, it wants to twist nose-up. Twisting more nose-up menas it generates more lift, which makes it want to twist even more nose-up... and very quickly your wing twists itself up and off the airplane. You deal with that by making your wing really, really stiff (which is what the X-29 did using tailored composites).

At least, thatís what I remember from aeroelasticity class
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  #29  
Old 11-22-2018, 07:50 AM
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jcarne jcarne is offline
 
Join Date: Jul 2016
Location: Worland, Wyoming
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I definitely agree with you, 3/8" sweep would not worry me in the slightest. Just out of curiosity though are your rear spars hitting the rivet pointed out in this picture? I put flush rivets here (someone said there may be interference here) to avoid this but I'm wondering if it was necessary.

rear spar rivet by Jereme Carne, on Flickr
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  #30  
Old 11-22-2018, 09:37 AM
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rmartingt rmartingt is offline
 
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Location: Savannah, GA
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Quote:
Originally Posted by jcarne View Post
I definitely agree with you, 3/8" sweep would not worry me in the slightest. Just out of curiosity though are your rear spars hitting the rivet pointed out in this picture? I put flush rivets here (someone said there may be interference here) to avoid this but I'm wondering if it was necessary.
The left side is; I'll trim it when the wings come off to eliminate contact but I'm not messing with it just to fix something that's within tolerance.
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