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01-05-2020, 07:01 PM
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Join Date: Nov 2019
Location: Mobile/ RV traveler
Posts: 1
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RV7 with 9 wings? possible?
I am preparing to start an RV7, It meets our mission perfectly.
With the thought of Experimental Aviation in mind, I wonder since the 9 shares fuselage and empennage, would it be possible to build a set of 9 wings and "swap" wings out for higher altitude X-country trips? I have not put the costs to the calculator, I would imagine the cost of the wing kits (if Vans would even sell them to a 7 owner) would take a long time to recoup compared to the cruise economy improvement. There is the obvious change in wing aspect ratio, slight increase in SqFt., and smaller tanks. Thinking there maybe CG issues also with the wing chord change and the heavier AIO-360 that is planned.
It is just a thought, it is not like swapping wings and re-rigging would be a 30 minute job. Is just more of a theoretical question. The 7 has enough wing and speed, ceiling is very close to a 9 already.
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01-05-2020, 07:37 PM
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Join Date: Mar 2013
Location: Snoqualmie, wa
Posts: 393
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The first time you attempt to install the close tolerance wing bolts will cure you of any thoughts of ever removing them! :-)
Also, the 9 and the 7 have very similar fuselages, but they are not identical.
__________________
Darin
Snoqualmie WA
RV-9A Sold
RV-10 Building - FWF
www.DarinAnderson.com
2020 donation sent!
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01-05-2020, 07:40 PM
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Join Date: Nov 2006
Location: Savannah, GA
Posts: 1,029
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No, you can't install 9 wings on a 7, or vice-versa.
One option might be swappable wing tips on a 7. Properly engineered, they could provide cruise benefits on long flights yet be swapped out for standard tips for local/fun flying. You'd take a g-limit hit with thw cruise tips in place.
But that's a lot of trouble for smallish gains, unless you rwallylike doing that sort of thing and can do it properly. I've thought about at least designing some (or a set of tapered wings) as an educational exercise but I'm an AE by schooling and profession.
__________________
RV-7ER - finishing kit and systems installation
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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01-05-2020, 07:46 PM
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Join Date: Nov 2016
Location: Camas, WA
Posts: 370
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Isn't the carry through different on the 9 as well?
Also, as I recall the H-Stab on the RV-9 is perpendicular to the wing and larger than the RV-7, whereas the RV-7 is smaller and tapered toward the outboard tips a bit.
__________________
Dan Reed
Camas, WA
RV-7A - Slider in progress - N167DR (reserved)
Sitting in the paint booth, then final assembly/inspection time
2018 and 2019 VAF dues paid
Last edited by dreed : 01-05-2020 at 07:53 PM.
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01-05-2020, 07:51 PM
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Join Date: Feb 2005
Location: Victoria B.C.
Posts: 1,266
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Not practical. Buy the 7, it still performs well in the upper teens.
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01-05-2020, 07:51 PM
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Join Date: Jan 2005
Location: SC
Posts: 12,887
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The empinage is not the same. The HS and elevators are larger on the -9. I was told by "Van's" that on the prototype, which was a -6 with -9 wings, that the slotted flaps blanketed the HS and elevators, which is why the -9 has that big slab of an HS.
The VS and rudder are the same.
As for the wings, fuel tank support brackets are different and may be in a different location and the forward side skins are different. I don't know if the rest spar is in the same location on the -7 & -9. I do know they share the same dihedral but don't know about the bolt pattern.
__________________
Bill R.
RV-9 (Yes, it's a dragon tail)
O-360 w/ dual P-mags
Build the plane you want, not the plane others want you to build!
SC86 - Easley, SC
www.repucci.com/bill/baf.html
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01-05-2020, 07:57 PM
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Join Date: Aug 2011
Location: Jeffersonville, IN
Posts: 393
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Only took me a couple days to get all the wing bolts in, and I magically learned French in teh process. Even if they did fit, I dread ever having to remove or install those bolts again in my lifetime. Let alone do it on a regular basis.
Love my 9, but I don't think the 7 or 9 are different enough that you need "both". If you plan to go upside down go 7 and be done. If no upside down needed the 9 is awesome.
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Jeff Scott
RV9A First Flight 9/30/19
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01-05-2020, 08:18 PM
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Join Date: Jan 2016
Location: Southwest
Posts: 1,119
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Others
As others have me tion the 9 and 7 share common parts but are not the same pick your poison, the 7 or the 9. If you cant decide , then pick the 14
__________________
John S
WARNING! Information presented in this post is my opinion. All users of info have sole responsibility for determining accuracy or suitability for their use.
Dues paid 2020, worth every penny
RV9A- Status:
Tail 98% done
Wings 98% done
Fuselage Kit 98% done
Finishing Kit 35% canopy done for now
Electrical 5% in work
Firewall Forward 5% in work
www.pilotjohnsrv9.blogspot.com
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01-05-2020, 08:19 PM
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Join Date: Dec 2017
Location: Southern Maryland
Posts: 134
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Every theoretical wing swap evolution would probably trigger another phase 1 type of event.
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RV-7:
Empennage complete!
Wings in progress
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01-05-2020, 08:29 PM
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Join Date: Jul 2005
Location: Hubbard Oregon
Posts: 9,035
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Quote:
Originally Posted by N941WR
The empinage is not the same. The HS and elevators are larger on the -9. I was told by "Van's" that on the prototype, which was a -6 with -9 wings, that the slotted flaps blanketed the HS and elevators, which is why the -9 has that big slab of an HS.
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Nope
Research center of lift change and pitching moment induced by flap deployment.
__________________
Opinions, information and comments are my own unless stated otherwise. They do not necessarily represent the direction/opinions of my employer.
Scott McDaniels
Van's Aircraft Engineering Prototype Shop Manager
Hubbard, Oregon
RV-6A (aka "Junkyard Special ")
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