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View Poll Results: Is the RV-12 a suitable plateform for experimentation?
Yes, it is Experimental and anything goes. 42 54.55%
No, the 12 is a special case unlike other RVs. 35 45.45%
Voters: 77. You may not vote on this poll

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  #11  
Old 01-30-2012, 10:05 AM
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N941WR N941WR is offline
 
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Quote:
Originally Posted by joedallas View Post
Bill the CG. Is an issue the engine choice and location of the battery and fuel tanks?
I have run numbers on a few scenarios that I think will work.
Until I have more information on alternate engines I am not sure that it will.
I will not do if the numbers don?t work, but I think they will
That?s why I will build the wings last.
Good luck with your planned for changes, I do hope they work out!
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  #12  
Old 01-30-2012, 10:18 AM
skydiverlv skydiverlv is offline
 
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Originally Posted by N941WR View Post
The leading edge tanks on the other RV's put the fuel forward of the CG and the CG moves aft as fuel is burned. With the -12, the CG moves forward as fuel is burned.

I believe that if you put wing tanks on the -12, you will have a major FWD CG issue. With the people sitting so far forward in the -12, you will have to add some weight in the tail to offset the change. That or move the people aft.

What you are proposing is a slippery slope...
How about pulling the UL or Jab engine closer to the firewall, possibly moving CG enough to allow wing tanks? That would solve multiple issues discussed.
I considered wing tanks early on and knew it would not be possible with my build nor do I have the time to design/engineer/manufacture them so I quickly dismissed it One concern I had was the wing was not designed for the fuel load in turbulence.
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  #13  
Old 01-30-2012, 10:23 AM
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Originally Posted by DonFromTX View Post
Out of consideration to Vans, that is why my aircraft bears not one reference to Vans, the name will not be on registration or AW certificates. If I crash and burn, it will not be connected to Vans in any way, nobody can decide to bring a lawsuit against Vans.
If the name Don has on his registration shows up in the news it may cause a national crisis.
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  #14  
Old 01-30-2012, 10:54 AM
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Default Fuel Tanks

I have looked at the jab and the UL the jab should work the UL the jury is still out. need more data.



Quote:
Originally Posted by skydiverlv View Post
How about pulling the UL or Jab engine closer to the firewall, possibly moving CG enough to allow wing tanks? That would solve multiple issues discussed.
I considered wing tanks early on and knew it would not be possible with my build nor do I have the time to design/engineer/manufacture them so I quickly dismissed it One concern I had was the wing was not designed for the fuel load in turbulence.
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  #15  
Old 01-30-2012, 11:14 AM
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You must remember the time in which the -12 was introduced. That was in the midst of a full FAA reconsideration of the 51% rule. The proposals about changes to that rule had a lot of confusion built into them - lots of different percentages, lack of clarity as to what words like "fabrication" meant. And the time frame for all that getting cleared up was a year or two AFTER the -12 could be shipping. Waiting wouldn't make sense. So initially having it as an E-LSA sidestepped all of that mess (and besides having what I - a non-A&P - think are considerable advantages as E-LSA.) Then as mentioned - once the FAA 51% situation got clarified -Van's went the extra mile - and proved the kit as a 51% - making it EASY for builders to build it as EAB if they wanted. Wonderful!

Regarding removable wings - it is only clever engineering and a few parts that make them removable. Not a lot of extra cost. I don't think any significant weight savings would result if they were non-removable. It has been VERY handy already in building that they are removable. And it opens up the whole world of painting in a good auto shop (see this thread http://www.vansairforce.com/communit...ad.php?t=67760 So I see that (by itself) as a non-issue.

The associated problem though is the fuel tank, and wing tanks will take some engineering. I think using a couple of quick-disconnect fittings at the wing root for fuel would be no big deal - adding a few minutes to wing removal at worst. The fuel plumbing would be more complicated. Putting the fuel tanks in the wings BEHIND the spar might be interesting for CG but pose more significant structural challenges. It will be fun to see what folks come up with.

I think as a newbie you can get as much of the "E" you want in building a -12! A 3-time builder might find it quite limiting in that regard though. (Significantly higher horsepower? It is not aerobatic - and have you looked at the tail attachment? I would like maybe ~115HP (Rotax 914) and a bigger alternator and IFR!)
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  #16  
Old 01-30-2012, 11:22 AM
lewy lewy is offline
 
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Default Don from Texas

Change, don, I don't understand why you purchased the Rv-12 when u want to change everything about it. Would it have been easier to design your own aircraft to your wants and likings and left Vans out of the picture. What school did you get your aero-engineering degree from, Vans did a great job with every aspect of the RV-12, that is why it is the most popular lsa aircraft on the market, my vote is to leave it as us.
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  #17  
Old 01-30-2012, 11:45 AM
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Default Fuel Tanks

I have a structural engineering background not an Aeronautical engineering background.
I believe the moment on the spar is less with the fuel in the wing then in the fuselage.
The rotational affect on the spar from the fuel in turbulence is above my pay scale. I will need help with this engineering if I decide to do this, the front and back connections are in sheer not moment this concerns me.






Quote:
Originally Posted by skydiverlv View Post
One concern I had was the wing was not designed for the fuel load in turbulence.
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  #18  
Old 01-30-2012, 12:28 PM
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Whoa there, I never said I wanted to "change everything", on the contrary I feel the RV 12 is the finest out there, lots and lots to like about it. Even the removeable wings which I don't particularly need, seem to me to be far more firmly attached than even the rest of the RV lineup! You are correct about me not having an aero-engineering degree, I may be on really thin ice here therefore, but somehow thought I could put in a Moeller fuel gauge, and install a backup airspeed indicator and altimeter without the degree paperwork, especially since those with them don't think we should do that.
I fully respect those that feel more comfortable building 100% according to the ELSA rules, I only hope you can respect those that wish to change things around a bit. After all, is that not the start of Vans, remaking a proven kit into something he liked better?

.
Quote:
Originally Posted by lewy View Post
Change, don, I don't understand why you purchased the Rv-12 when u want to change everything about it. Would it have been easier to design your own aircraft to your wants and likings and left Vans out of the picture. What school did you get your aero-engineering degree from, Vans did a great job with every aspect of the RV-12, that is why it is the most popular lsa aircraft on the market, my vote is to leave it as us.
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  #19  
Old 01-30-2012, 12:32 PM
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I have always been in awe of the wingtip tanks added to production aircraft - with no (or minimal) change to the structure. Would not think that would work out well, but it seems to.

Quote:
Originally Posted by joedallas View Post
I have a structural engineering background not an Aeronautical engineering background.
I believe the moment on the spar is less with the fuel in the wing then in the fuselage.
The rotational affect on the spar from the fuel in turbulence is above my pay scale. I will need help with this engineering if I decide to do this, the front and back connections are in sheer not moment this concerns me.
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  #20  
Old 01-30-2012, 01:21 PM
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Don I looked at tip tanks for the 12, the spar at that end of the wing would need a lot of redesign and on a hard landing would add a lot moment to the spar at the fuselage. Small tanks maybe, but not big enough to replace the main tank
Can?t wait to see your Viking Flying.


Quote:
Originally Posted by DonFromTX View Post
I have always been in awe of the wingtip tanks added to production aircraft - with no (or minimal) change to the structure. Would not think that would work out well, but it seems to.
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