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Joe's Fuel Tank

R

rgmwa

Well Known Member
Joe,

Thanks for the photos and diagrams. Although the tank is more complex than the original, it really cleans up the baggage area and makes the RV-12 an even better touring aircraft. Distributing the fuel load across the width of the cabin and keeping the weight lower down in the aircraft, plus maintaining a more constant cg position as the fuel is used also seem to me to be significant advantages.

In addition, it would be easy to add another 5 gallons or so with very little change to the aircraft balance. Add to that the fact that the tank is perhaps anchored better than the original and the weight is more uniformly distributed and braced by the C channel (?), it may well be safer in a crash too.

I hope Van's take a serious look at the design, but in the meantime, can you confirm the tank material thickness and type, and also what sender unit you are using? If I've understood the photos correctly, the bottom rear edge of the tank is screw-fixed to the baggage floor, but I'm not sure where else it's fixed to the structure. Any further construction details would be appreciated. Thanks in advance.
 
Missed it. Joe....post some photos!

Found them in the Modifications post!

Looks real neat Joe!! What did Van have to say?
 
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What did Van have to say?
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Van said that my tank had advantages. When asked by another builder if Van's Aircraft would offer a tank like mine, Van replied, "Not immediately." I interpret that to mean that Van liked my tank and will consider putting a similar one in the RV-12. If they do, designing and testing and producing will take a long time.
My tank is 39" wide and 13.25" high. Any bigger and it might not fit. If I ever built another tank, I would only make it 13.125" high. The sump on the bottom of the tank can not be too deep or it will interfere with the flaperon pushrods.
I purchased 03-30860 5052-H32 SHEET .032 48" X 72" from aircraftspruce.com. Except for the tank ends, the tank skin is all one piece and overlaps on the 2.13" vertical side. There are two internal ribs for strength and to prevent the fuel from sloshing from side to side. I should have made bigger holes in the ribs because the tank can not accept fuel as fast as an airport hose delivers the fuel. I ran the tank over even though it was not full because the fuel did not flow into the other two compartments fast enough.
I bought the magnetic-reed-switch type of fuel sending unit from Amazon.
http://www.amazon.com/gp/product/B000MTCRC8
I do not like the way it jumps in steps (15 or 16 of them) instead of giving an infinitely variable level like the potentiometer type. I chose this type of sender because I did not know if there was room for a swing-arm type of sender. The sending unit is made for 15" tanks, however it is only 14" long. They want 1" clearance between probe and tank bottom. I ignored that. Since the tank is only 13.25 inches high and the probe is 14" long, the end of the probe extends into the sump. I did that to get a more accurate reading when the tank is almost empty. But I do not plan to ever run the tank that low.
I have added a few more pictures to Picasa of a cardboard mockup
https://picasaweb.google.com/117081108891056780334/SEATBACKFUELTANK?authuser=0&authkey=Gv1sRgCLnX4YDy0PuVaQ&feat=directlink
that shows the corners cut out of the tank so that it will fit around the aircraft center section.
A very hard landing that deforms the center channel will also damage the fuel tank. The same can be said about the original tank. But since my tank is longer, it is more susceptible to damage.
I installed 6 nutplates to the baggage floor ribs. The angle on the aft-bottom of the tank is fastened to those nutplates with #8 screws. Each of the 4 tank ribs has a nutplate on the inside of the tank. 4 of AN3 bolts go through the heavy center channel and into the tank ribs. The bolts are sealed with proseal. 1/8" thick aluminum washers between the tank and center channel prevent interference with rivet heads that are on both the tank and center channel.
Joe Gores
 
rgmwa said:
Add to that the fact that the tank is perhaps anchored better than the original and the weight is more uniformly distributed and braced by the C channel (?), it may well be safer in a crash too.

.
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Some of the many tests required by ASTM F2245 for S-LSA certification are crash load tests and hydrolic pressure burst tests of the fuel tank. These tests were all completed and passed on the RV-12 fuel tank.
Can the same be said for this tank?

It is true that a lot can be determined by just general examination, but until you do the tests, there is no way to know for sure. With all of the testing I have been involved in over the years, I have been surprised more times than I can remember... just because something looks like a strong design, doesn't mean it is. It may very well be, but until you test to verify, it is just a guess.
 
Point taken, Scott. Clearly, Joe's tank has not been tested to comply with the standards, so anyone who builds one is on their own. Nor am I necessarily going to build one myself at this time, given that I already have the standard tank kit sitting on my workbench. I want to get my plane finished and flying, and even though I'm going AB-E, certification will be easier if I stick closely to the plans.

But I think he's come up with a great idea, and maybe Vans could consider it as an alternative to the current tank. It makes that space in the back of the plane a lot more accessible and usable, and it looks like it would also benefit load distribution and trim. Obviously it would take time and money to develop a new tank design into a viable kit option, but any improvement that makes a great plane even better can only be good for sales.

rvbuilder2002 said:
Some of the many tests required by ASTM F2245 for S-LSA certification are crash load tests and hydrolic pressure burst tests of the fuel tank. These tests were all completed and passed on the RV-12 fuel tank.
Can the same be said for this tank?

It is true that a lot can be determined by just general examination, but until you do the tests, there is no way to know for sure. With all of the testing I have been involved in over the years, I have been surprised more times than I can remember... just because something looks like a strong design, doesn't mean it is. It may very well be, but until you test to verify, it is just a guess.
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rgmwa said:
It makes that space in the back of the plane a lot more accessible and usable, and it looks like it would also benefit load distribution and trim.
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I agree, and had envisioned a tank similar, but the design took a different direction. Just suggesting caution to builders if they start considering any modifications to any part of the fuel system.
 
I personnally think it is a great idea. Certainly testing would be necessary before Van could go ahead, and it would be re-assuring to those of us who will likely follow Joe's lead. I suspect none of us would like to build one, fill it with water and then drop it from about 4 ft. to see if it bursts. I am surprised tho that no one has mentioned the biggest advantage which in my opinion is YOU DON'T HAVE TO TAKE THE D--N THING OUT EVERY YEAR AT INSPECTION TIME. Not only is that a bit of work and a nuisance, (just did it) but we have to open the fuel lines every annual so sooner or later the fuel line integrity becomes an issue of the MAJOR variety. Joe's concept never comes out as the rear fuse is accessible w/o disturbing anything. I for one may with the help of friend who is an engr in strength and design may try it, or maybe just repro Joe's. The man clearly has thought this thing thru pretty well. Good going Joe!
Dick Seiders 120093
 
Dick I was strongly against removing my tank every year too, possibly introducing leaks and dirt to the system. You can look at my kit log recent entries for a solution I copied from another builder, my tank will stay in!
 
Thanks Dick

The man clearly has thought this thing thru pretty well. Good going Joe!
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Thanks Dick and to others who like my fuel tank. Hopefully Van's Aircraft will read the above comments and decide that this new tank design will improve their great airplane and make customers happy and increase sales.. At OSH I suggested to Ken K that if Van' adopts my idea, that I be given a new tank as a suggestion reward. I would love to be a beta tester. I am sure that their tank will be better than mine, designed by engineers and tested and made with CNC precision.
I agree with Scott that changes should be made with caution. I do not know what I don't know. There could be a serious flaw in my tank that has not yet become apparent. So far there are about 10 hours on the new tank on a couple of long cross country flights including one to OSH and at altitudes as low as 600 up to 10,000.
So far so good.
Joe Gores
 
Well, at least Van, Ken and Scott all know about the tank, and they are clearly the right people to take the idea forward. The advantages of Joe's approach are so obvious that I'm sure a little market research would show strong support from both prospective customers and existing builders. I for one would change to over to an approved design without hesitation.
 
I have appreciated the many comments that Joe has offered during the build process.

I do not mean for my next comments to in any way demean the Rv-12. It is a very good plane. It can be improved. We all look at the D model P-51 and say wow. The A and B , not as much.The Rv-12 we are all flying is I guess the B model since the yellow one was modified. I'd love to see the Rv-12 D, the one that has all the little upgrades that takes it to the next level. I don't want to scratch build Joe's tank, but by the same token I don't like pulling the tank every annual. If Van's will offer one, I will buy it. Great design Joe.
 
Should we start a petition drive to convince Van's that this tank is now a "Consumer Demand"? This tank appears to be a stroke of brilliance. The talent that is abound in the experimental world never ceases to amaze me. I have never met Joe, but he is one of those forum contributors that "When he writes, people read". I want that tank!!! Thank you Mr. Gores!
 
The current tank design has actually been the reason that I have hesitated purchasing the plane. I want a baggage area that offers more useful space. I'll be watching to see what vans does. Would love to see that design in a molded tank.
 
Tank

If Van ever does offer a new tank like Joe's I sure hope its a 25-gallon unit.
That extra hour of flying is pretty important out west where things are spread apart a lot
 
JohnF said:
If Van ever does offer a new tank like Joe's I sure hope its a 25-gallon unit. That extra hour of flying is pretty important out west where things are spread apart a lot
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Often important out here in Australia too. It's a big country! Twenty gallons is OK most of the time, but 25 would be better for those long`outback' trips.
 
Baggage Space?

Folk are responding to this topic because they want more baggage space? Do you really mean space, or weight?

I am contemplating a two-week tour and I think there's already plenty of space to accommodate 50lbs of baggage. However, I'd like to carry more luggage weight.

In fact I could put far more than 50lbs in the back and still be within the CofG limits. Is this a structural issue? Certainly the floor structure appears strong enough to take more. Even 50 x 4G is only 200 lbs. I'm heavier than that and stood in the baggage area when building the plane.

Cheers...Keith
 
gblwy said:
Folk are responding to this topic because they want more baggage space? Do you really mean space, or weight?

I am contemplating a two-week tour and I think there's already plenty of space to accommodate 50lbs of baggage. However, I'd like to carry more luggage weight.

In fact I could put far more than 50lbs in the back and still be within the CofG limits. Is this a structural issue? Certainly the floor structure appears strong enough to take more. Even 50 x 4G is only 200 lbs. I'm heavier than that and stood in the baggage area when building the plane.

Cheers...Keith
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I just like the idea of baggage space being well....baggage space. I like to go camping alot, and I would like to be able to haul my camping gear in whatever aircraft I'm flying, and you can't really do that with the current RV-12 design with the fuel tank taking up half of your baggage space.
 
My observation while building fuselage was that there is a weakness (do not interpret my comment as a design flaw because I AM NOT an aeronautical engineer) in the structure between the front and rear bulkhead F-1204 and
F1204D beneath the bulkhead trough. The loading of the tail weight and aft portion of fuel tank where it attaches to the rear bulkhead is carried by side skins and the bottom stiffeners. This was verified after viewing photos of the hard landing experienced by 331RV. One could assume that moving tank forward with a more direct downward loading of fuel tank/fuel weight to the center bulkhead should leave a greater weight capacity in the baggage area without violating the current tested loading on structure.
 
NCGAPilot said:
I just like the idea of baggage space being well....baggage space. I like to go camping alot, and I would like to be able to haul my camping gear in whatever aircraft I'm flying, and you can't really do that with the current RV-12 design with the fuel tank taking up half of your baggage space.
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I want more space too for bulky items. I'm fine with the weight.
 
I wondered when I first saw the production fuel tank why it didn't go all the way across the baggage area and just be shorter...
 
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Like it

Joe - Like the tank very much. Glad that you showed it to Van and his staff - that is the way to go. Like the tank - hope that Van's or you will build a 25 gallon tank. Cleans up the baggage area, puts the fuel closer to the cg, adds (hopefully) a few more gallons of fuel. Great idea. I will want one for sure.

If possible, please relocate the fuel inlet away from the lexan. windows.
 
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