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11-24-2010, 06:37 PM
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Join Date: Sep 2010
Location: Lethbridge, Alberta
Posts: 7
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De-lurk, and first of many questions
Hello fellow RV'ers
I guess it is time to step up and say Hi.
(What follows is a long rambling intro, the question is right at the bottom  )
We (Lizzy and I) currently fly an older 182, and love her, but after the last several annuals costing big $$, we have decided to upgrade to something newer. We thought of a T182, and even a Cirrus, but my Dad always told me money doesn't grow on trees, and I've discovered he was right.
I like toys, and I hate not having even more of das blinkenlights on the panel. I am currently doing my IFR rating. Lizzy is lower time than I, and is currently working on her night rating. We are both in our 50s. (Please don't tell Lizzy I said that  )
Our mission is fairly long cross-country flights. Think 2-4 hour legs. We do not fly around the patch much. Neither of us has done any aerobatics. Lizzy doesn't like them much, I am not so sure I might not. We tend to fly high, and have portable O2 in the cockpit. We both think an autopilot is an essential part of cross country flying.
The other side of the decision to build is that we love spending time together, especially making "stuff". We think this project may be a great way to continue how we spend our spare time. We are not too sure of our capabilities, especially with the engine side of things, but have always managed to figure out a way to get things done, and suspect this will be no different - at worst we can get an AME to work with us on the engine. I am fairly good with my hands. I have built model aircraft, houses, like crafting things out of steel. I have taken a small engine course. Lizzy is great at detail work, such as pastry, sewing, etc.
We both had a chance to fly the demonstrator, and were very impressed by most of what we saw. All aircraft are compromises, but we feel we may not need to make too many with a -10.
We plan to continue flying our 182 as we build. In fact, JYMmie is getting a factory reman at her annual this January ($$), which is a big part of why we are not starting earlier. That, and the fact that we realize how big a project this is, and we don't plan on committing until we are sure of ourselves.
So, please forgive any stupid questions. I have spent many hours looking through old threads and many builder sites, but still find myself wondering about things.
The question:
Have there been any wing failures in RVs?
The lack of a longer main spar overlap at the joint bothers me. My flying buddy correctly points out that there is not much overlap in our Cessna either, but we do have a strut. Perhaps it is the long overlap in the glider wings from my younger days that makes me think that it "just doesn't look right."
Can anyone put this bugaboo to rest for me? 
__________________
Currently flying 1974 C182
Planning RV10: + Wife-Pilot-Co-Builder on board and helping pull 
+ Trip to Aurora completed
+ Full set of plans on coffee table
+ Friend with flying RV-8A willing to help
- Working on still-unanswered questions before taking the plunge
http://cronje.ca
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11-24-2010, 07:40 PM
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Join Date: Jul 2007
Location: Delaware, OH
Posts: 435
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Quote:
Originally Posted by TLN
Hello fellow RV'ers
The question:
Have there been any wing failures in RVs?
The lack of a longer main spar overlap at the joint bothers me. My flying buddy correctly points out that there is not much overlap in our Cessna either, but we do have a strut. Perhaps it is the long overlap in the glider wings from my younger days that makes me think that it "just doesn't look right."
Can anyone put this bugaboo to rest for me? 
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Hello, Steve and welcome. It sounds like you guys are well suited for building. Should be fun.
Regarding your question,
I believe there were one or more wing failures on the RV-3 which prompted some modifications and ultimately a redesign.
I'm also aware of one RV-8 wing failure. Significant testing ensued and the the test wing failed as predicted (although I think it may have been at a slightly higher load than expected). The failure did not occur at the root, but closer to mid-span in my recollection (again, as predicted). Prevailing speculation is that the pilot pulled the wings off (over g). Speculation, nonetheless.
The -3B wing has been completely redesigned (hence the B designation) to make it similar to the -7, -8, -9, and -10 arrangement.
I've been in the engineering profession for about 20 years and don't see anything that sets alarm bells off for me. I haven't done any calculations, though, so I can only comment from the TLAR (that looks about right) perspective.
As long as the overlap and attachment is adequate to transfer the load from the spar caps of the wing to the caps in the center section, it's strong enough. I haven't seen a Cessna wing attachment, but having a strut, I'm guessing it's not a cantilever design...thus a completely different type of design.
If you have concerns, you should feel free to call Vans.
Good luck!
__________________
Mike Cencula
RV-7A (fuselage)
www.our7a.com
Betcha my pile-o-scrap is bigger than your pile-o-scrap.
Last edited by mcencula : 11-24-2010 at 07:42 PM.
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11-24-2010, 08:30 PM
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Join Date: Aug 2006
Location: Prairieville, LA
Posts: 118
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Welcome aboard
Welcome Steve. I do not have the engineering background (I am a maintenance test pilot on helicopters in the Army) to comment on any wing failures, but I can tell you I am not aware of any, and after reading about the load testing some of our builders across the pond have to do to certify their craft I have no concerns. The spar assemblies are stout and when they are mated during assembly the joint is solid. It is an issue that only Vans can truly answer for you, but it hasn't been an issue in our community as it is in another.
It is great to hear that you and your wife are in this together. That is really important on the project. It can bring you closer, or drive you farther apart. My girlfriend gave me the me or the airplane ultimatum...I am expecting first flight in January  This community is certainly a great place to get information, and over the years I have certainly received alot of help from the group. Many of the questions you will have will be in the archives, but anything asked is typically met with a rapid response as someone has had the same problem. Again, welcome aboard.
Eric Kallio
N518RV
Tying up loose ends before inspection
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11-24-2010, 08:37 PM
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Join Date: Oct 2005
Posts: 1,516
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Welcome new RV-10 builder
Hello Steve,
You seem to have all the right stuff to build an RV-10.
Your worries about the main spar overlap are unfounded and a bit like
questioning the size of the rear axle on a Chevy Suburban.
In all fairness I have looked at the wing spar attachment many times and had similar thoughts but I do trust Van's design engineers.
Looking at 30 years of Van's history I have no reason to believe that there is a flaw in wing spar attachment design.
The overlap spar design on gliders is much different in that the carry through structure is almost non existent and made up of the overlapping spars.
Looking at the carry through structure on the RV-10 is a massive assembly
of heavy aluminum and heavy gauge aluminum for the web.
I cannot tell you exactly why they do it this way but I can tell you that wing
attachment for a homebuilder is exceedingly simple and easy to accomplish
in a precise manner.
After flying an RV-8 for 8 years and now finishing an RV-10 I have never had a worry about wing root design.
The sooner you get started the sooner you finish 
__________________
Ernst Freitag
RV-8 finished (sold)
RV-10 Flyer 600 plus hours
Running on E10 mogas
Don't believe everything you know.
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11-24-2010, 09:25 PM
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Join Date: Sep 2010
Location: Lethbridge, Alberta
Posts: 7
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Mike, Eric and Ernst
Thanks for the welcome.
I appreciate the responses. Van's long history and solid reputation is one of the many reasons why we both like the RV hangar. I guess I just had to ask that question, as it has been niggling me for a while now, and just had to get out!
OK, so here is a more practical question:
Where are the instructions for testing the fuel tanks? I feel stupid, but don't seem to be able to find them.
Regards
Steve
__________________
Currently flying 1974 C182
Planning RV10: + Wife-Pilot-Co-Builder on board and helping pull 
+ Trip to Aurora completed
+ Full set of plans on coffee table
+ Friend with flying RV-8A willing to help
- Working on still-unanswered questions before taking the plunge
http://cronje.ca
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11-24-2010, 09:45 PM
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Join Date: Jul 2007
Location: Delaware, OH
Posts: 435
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Quote:
Originally Posted by TLN
Mike, Eric and Ernst
OK, so here is a more practical question:
Where are the instructions for testing the fuel tanks? I feel stupid, but don't seem to be able to find them.
Regards
Steve
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For the RV-7A, they're in the 8.5 x 11 instructions. Not sure on the -10...I believe the instructions and plans are more combined. The process is the same, regardless. Use a manometer and a bicycle pump to pressure the tank to 1 psi (~27.7 inches of water), and let it sit for a while. If the manometer stays put over an extended period of time, you're good to go (be sure to watch for the effect of temperature fluctuations).
Multiple websites (including mine) show the process.
Take care,
__________________
Mike Cencula
RV-7A (fuselage)
www.our7a.com
Betcha my pile-o-scrap is bigger than your pile-o-scrap.
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11-24-2010, 11:39 PM
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Join Date: Oct 2005
Posts: 1,516
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Steve,
I see your enthusiasm bubbling to the surface.
You do have unusually different questions for someone who has not started building yet. Something tells me you have been thinking about this for a while.
The fuel tank testing is usually a bridge you can "burn" when you get to it.
When you do approach a project like building an airplane you cannot possibly have all the problems worked out before you start. You will build small parts or sections at the time and each presents a few challenges but all can be solved when they are separated into small tasks.
Help is available especially on this forum where some vendors answer questions even on weekends.
As to your specific question.
Another way to test the fuel tank is to close all the openings attach a balloon
to one of the fittings and pressurize the tank until the balloon is inflated.
If it stays inflated for a couple of days your tank is tight.
Happy Thanksgiving
__________________
Ernst Freitag
RV-8 finished (sold)
RV-10 Flyer 600 plus hours
Running on E10 mogas
Don't believe everything you know.
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11-25-2010, 12:34 AM
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Join Date: Jul 2007
Location: Molalla, Oregon
Posts: 955
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Steve,
I used the balloon test on my tanks and it worked great. The balloon stayed fully inflated for 3 days before I took it off, so I'm confident they're good to go. I documented it with lots of pictures on my web site, too.
Van's sells the Fuel Tank Test Kit separately. Price: $6.00 The instructions for testing the tank are in the kit. The instructions tell you how to do it both ways.
One more thing. I suspect you're worried about making mistakes and you're trying to get it all figured out beforehand. Don't worry. We ALL make mistakes along the way. Just assume you'll make your share. The good news is, the parts are relatively cheap, especially in the beginning when you're likely to make most of them. So if you screw something up, you just toss it in the scrap pile (we all have one), order a new part and press on. More than anything else, this is a "learn as you go" kind of project.
Last edited by BSwayze : 11-25-2010 at 12:43 AM.
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11-25-2010, 01:23 AM
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Join Date: Oct 2007
Location: Belvidere, IL
Posts: 169
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Spars
Steve,
I'm an aerospace engineer and I analysed the RV-10 wing and carry-through. I can assure you it's very strong! This particular method of wing attachment is very common. Since the wing loads are reacted at the attachment bolts, there is no benefit to extending the spars further.
Sailplanes often use a tongue-and-fork configuration with overlapping spars. When properly designed, this method is lighter, but more complicated to build. In contrast, the airplane world usually sticks to simple designs.
Keep in mind... you can tear the wings off any machine, including the C182. I haven't heard of an RV-10 wing failure, but such an event would almost certainly be due to extreme pilot error.
__________________
David Shelton, Aerospace Engineer and Soaring Nut.
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11-25-2010, 05:57 AM
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Join Date: Jan 2005
Location: Louisville, Ga
Posts: 7,840
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Welcome Steve and Lizzy
Your background mirrors mine...model airplanes, cars, outbuildings and general handiwork.
Coupled with your wife's abilities and enthusiasm, starting on a -10 is a no-brainer.
What'r you waiting for?
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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