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  #11  
Old 03-26-2013, 12:11 AM
az_gila's Avatar
az_gila az_gila is offline
 
Join Date: Jan 2005
Location: 57AZ - NW Tucson area
Posts: 10,011
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Quote:
Originally Posted by rvmike View Post
Those pieces are on my plans. Say Hi to the wife.Mike
Mike,

Will do a Hi to Doris. Come see us before it gets too hot for the Southern Californians...

Those angles are not on my RV-6 plans sheet 18 with revisions up to R10.

I wonder when they got added...
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  #12  
Old 03-26-2013, 10:30 AM
stevemcgirr stevemcgirr is offline
 
Join Date: Aug 2010
Location: Eugene, OR
Posts: 159
Default Agreed

Hi Shannon,
The first responder, Carr, did correct my misunderstanding about the pressure. To clarify, it appears that 1 psi is PLENTY, and should not be exceeded. I thought I would repeat that here in case anyone reads my first post and thinks I am still going to pressure test above that. I'm not.

A reason you may have seen an increase in pressure as your tank heated is that if there is fuel in the vent line, as may happen if you fill "to the brim", the fuel will need to be pushed up the vertical segment of the vent line before being expelled, and this can result in a pressure column about 18 inches high (but still less than 1 psi)
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  #13  
Old 05-24-2019, 06:01 PM
SteFree RV-8 SteFree RV-8 is offline
 
Join Date: Jan 2018
Location: Phoenix
Posts: 20
Default Testing tanks

Hi guys,

I am testing my left tank now. I am starting with the balloon method to see where things are right now. From what I read the balloon is more of a "safety" feature in that a balloon would POP before you could over inflate a tank. I popped a balloon testing this out. It is amazing because the balloon barely inflates and then all of a sudden it goes from zero to 60 in like 1 second and POP!

I found the weak point in my test to be the seal at the base of the balloon itself. No matter what I tried there was air leaking out. So, I took some tubing and put it over the vent tube and then put a balloon on the end of the tube. Actually I got a bit whimsical and put a rubber glove to wave at me.

Then I filled tank with air and let it sit. The glove stayed full for some time but after a while it started to deflate. But what balloon have you ever blown up that does not lose air?

I filled the glove up again and this time I sprayed soapy water on seams. I did not see any bubbling on any of the seams I sprayed. Can anyone recommend though the best practice for doing this? I mean, I just "wung it" on a soap to water ratio. Is there a specific product I should be using?

It seems like no matter what and no matter how many times you test you need to bite the bullet, fill the tank with fuel and see what happens.

I also used a full quart on one tank. I gooped all of the seams, the shop side of all rivets and feel like I probably over did it in on the end ribs. I also drew a bead of goop along along all inner seams for ribs...basically anywhere I could access. I feel like the weak spot are the rivets themselves.

I hope I got this right. Building the tanks is not my favorite part of this project so far. It seems to me there has to be a better way.

Steve
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Steve Freeman
Phoenix, AZ
Built and Flying Zenith CH650, N902AL
Now Building RV-8

"If you choose not to decide you still have made a choice."

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Last edited by SteFree RV-8 : 05-24-2019 at 06:03 PM.
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  #14  
Old 05-24-2019, 10:12 PM
PhatRV PhatRV is offline
 
Join Date: Mar 2018
Location: Buena Park, California
Posts: 279
Default

Hi Steve,

I just finished leak testing my RV8 fuel tanks. You must be careful how much you pressurize the tank, even using the balloon method. See this thread

http://www.vansairforce.com/communit...d.php?t=171587

For the soapy water, I mixed in a lot of Dawn liquid soap to ensure plenty of bubbling if there is a leak. You can verify the soap concentration at the base of the balloon as there will be small leaks there.
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  #15  
Old 05-25-2019, 06:17 AM
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DanH DanH is offline
 
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Location: 08A
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Default

RV tanks are multi-part, riveted structures bolted into a larger structure which bends and twists in service. There is no practical shop test which can duplicate the service loads.

The shop test just finds the obvious leaks. Don't obsess over it.
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  #16  
Old 05-25-2019, 07:50 AM
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Larry DeCamp Larry DeCamp is offline
 
Join Date: Apr 2010
Location: Clinton, Indiana
Posts: 997
Default Thank you Dan

This makes me feel better. I fuel tested my tanks FULL of AV gas for a whole winter. After 100 hrs of flying, and a couple winter/summer temp cycles, I started to get some rivet weepers. I didn?t build the tanks but I do need to suck some Loctite in this summer.
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RV-4 fastback w/ Superior roller 360/AFP/G3X/CPI/Catto3b
Clinton, IN
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  #17  
Old 05-25-2019, 03:53 PM
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Piper J3 Piper J3 is offline
 
Join Date: Nov 2014
Location: Hinckley, Ohio
Posts: 2,065
Default

Look here.... http://www.vansairforce.com/communit...2&postcount=28

and here.... http://www.vansairforce.com/communit...1&postcount=30
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  #18  
Old 05-27-2019, 08:31 AM
SteFree RV-8 SteFree RV-8 is offline
 
Join Date: Jan 2018
Location: Phoenix
Posts: 20
Default Fuel Level Sender Confusion

Hi Guys,

Now for my new dilema...

Before I sealed up the tanks I tested the fuel sender probably 20 times to a test gauge I have. When I moved the float to the top of the tank the fuel level would go up to full when the float was at the bottom of the tank the level would show (close to) empty.

Due to the way the float wire is bent and how the sender installs it is virtually impossible to install it upside down.

Now, with my tanks sealed up (and air/soapy bubble tested) I filled tank with fuel to test (which does not seem to be leaking YAY!) but much to my chagrin, surprise, frustration and disbelief, the fuel gauge seems to run backwards now. When the tank is empty the gauge shows full and as I add fuel the needle moves from FULL to Empty. The sender wire is connected to the sender post on gauge, ground to ground and power to power.

I don't understand what could have happened here. Does anyone have any ideas what I could possibly have done?

I am planning on using digital fuel gauge which is programmed based on fuel level in tank so I think I will get past this with the "real" gauge I plan on using (I will also be installing fuel flow) but this is really driving me nuts. I don't know what happened.
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Phoenix, AZ
Built and Flying Zenith CH650, N902AL
Now Building RV-8

"If you choose not to decide you still have made a choice."

Neal Peart
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