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Hamburger 3330 Fuel filter

Jegs is a reputable company and Hamburger has been manufacturing auto race parts for many years so no problem there.

It's kinda small though. Think about the filter area and how quickly it could fill with debris and stop you fuel flow.

BTW, this is posted in the RV-12 area. Don't they just have one fuel tank in the fuse?
 
Hamburger fuel filter.

Yes they do
I have built home made tanks in the wings of my 12

http://joesrv12.com/Builder Log/al_06_03.htm

and a header tank under the floor in the baggage area

http://joesrv12.com/Builder Log/al_06_05.htm

There are screens on the fuel pickup fittings in the tanks

The wing tanks feed the header tank and there will be a filter at each tank.

And also a fuel gauge at each tank.

Thanks

Joe Dallas






Jegs is a reputable company and Hamburger has been manufacturing auto race parts for many years so no problem there.

It's kinda small though. Think about the filter area and how quickly it could fill with debris and stop you fuel flow.

BTW, this is posted in the RV-12 area. Don't they just have one fuel tank in the fuse?
 
I agree, to small and to fine to be on the suction side, especially with auto fuel!
 
Looking for a good filter

[Walt

I agree

I have a small place that I can get to easy

To use a larger filter I would have to put in the wings and it would be harder to service

I will look for a slightly larger filter
at about 50 to 70 Micron

The pump and filter are lower than the wing tanks
and I will not use auto fuel

Is anyone using a fuel filter in front of the Facet 40105 fuel pump and do you know what Facet recommends


( I just checked Facet site they recommend a pre-filter of 74 Micron in front of the pump )

Thanks

Joe Dallas




QUOTE=Walt;1076824]I agree, to small and to fine to be on the suction side, especially with auto fuel![/QUOTE]
 
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Shear Continuity?

Joe, how do you carry the shear load through those middle ribs?

A_06_03_05.jpg


Dave
 
Section modulus

Not sure what you are asking.
I think the answer you are asking for is

The section modulus of the top and bottom cord.

Section modulus is a geometric property for a given cross-section used in the design of beams or flexural members.

Joe Dallas





Joe, how do you carry the shear load through those middle ribs?

A_06_03_05.jpg


Dave
 
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The section modulus describes the relationship between the bending load and the bending stress. I've shown a somewhat arbitrary load in the figure below, but any ground or air or handling load will introduce loads to the ribs. For that matter, load will go in to the ribs from the rear spar. Also, if the load is indeed from the fuel, unless the tank is attached to the top cap of the rib, all the shear force will be on the bottom cap, because the load path round the back of the rib and then forward across the top cap appears relatively flexible compared to the more direct load on the bottom cap.

24ymigw.jpg


The shear is the actual force being carried and I showed that in red. The blue vertical arrows represent the reaction shear forces due to this load, while the horizontal arrows represent the reaction forces on the spar from the load. In your photo, the shear is carried into the spar by the flange on the front of the rib, and the fasteners between the rib and spar there, and that appears to be in order. But there's very little material at the forward end of the ribs to connect to those flanges, and it's not clear how that shear load is transferred.

If the stiffness at those points is considerably lower than the beefed-up rib flange assembly, the forward end of the ribs can act as a hinge. In that case, those ribs, having little shear stiffness, can't carry much load.

This stands in contrast to the significant amount of material and the generous radius of the forward lightening hole at the front of the RV-12 ribs, as the factory designed them. Also, note the formed bead around the hole, which helps prevent local buckling.

Hence my post.

Dave
 
moment connection between the rib and the spar

I think we are looking at this a little different

I would call that a moment connection between the rib and the spar

The top and bottom flange is made of two ribs and a 1" x 1" .063 angle with a screw to the spar flange in a shear connection also the wing skin has two rows of rivets top and bottom to help with the shear load from the moment connection. The section modulus of the top and bottom flange assemblies of the rib are more then required to carry the wing square foot load x 4.

This is not an endorsement of my design and should not be used anyone.


Joe Dallas





The section modulus describes the relationship between the bending load and the bending stress. I've shown a somewhat arbitrary load in the figure below, but any ground or air or handling load will introduce loads to the ribs. For that matter, load will go in to the ribs from the rear spar. Also, if the load is indeed from the fuel, unless the tank is attached to the top cap of the rib, all the shear force will be on the bottom cap, because the load path round the back of the rib and then forward across the top cap appears relatively flexible compared to the more direct load on the bottom cap.

24ymigw.jpg


The shear is the actual force being carried and I showed that in red. The blue vertical arrows represent the reaction shear forces due to this load, while the horizontal arrows represent the reaction forces on the spar from the load. In your photo, the shear is carried into the spar by the flange on the front of the rib, and the fasteners between the rib and spar there, and that appears to be in order. But there's very little material at the forward end of the ribs to connect to those flanges, and it's not clear how that shear load is transferred.

If the stiffness at those points is considerably lower than the beefed-up rib flange assembly, the forward end of the ribs can act as a hinge. In that case, those ribs, having little shear stiffness, can't carry much load.

This stands in contrast to the significant amount of material and the generous radius of the forward lightening hole at the front of the RV-12 ribs, as the factory designed them. Also, note the formed bead around the hole, which helps prevent local buckling.

Hence my post.

Dave
 
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...

24ymigw.jpg


The shear is the actual force being carried and I showed that in red. The blue vertical arrows represent the reaction shear forces due to this load, while the horizontal arrows represent the reaction forces on the spar from the load. In your photo, the shear is carried into the spar by the flange on the front of the rib, and the fasteners between the rib and spar there, and that appears to be in order. But there's very little material at the forward end of the ribs to connect to those flanges, and it's not clear how that shear load is transferred.

If the stiffness at those points is considerably lower than the beefed-up rib flange assembly, the forward end of the ribs can act as a hinge. In that case, those ribs, having little shear stiffness, can't carry much load.

This stands in contrast to the significant amount of material and the generous radius of the forward lightening hole at the front of the RV-12 ribs, as the factory designed them. Also, note the formed bead around the hole, which helps prevent local buckling...

I'd have the very same concerns. I figure that wherever an existing well-optimized design has a bunch of metal, it's because it serves a relatively important purpose.
 
2 x 12 and a bar-joist

This is like the difference between a 2 x 12 and a bar-joist

The top and bottom do all the work.


I'd have the very same concerns. I figure that wherever an existing well-optimized design has a bunch of metal, it's because it serves a relatively important purpose.
 
We can agree to disagree

In my view it is a moment connection with about a 3' arm
the up or down force acts on the spar based on its arm either
in compression or tension and in shear to or from the spar.

the vertical lift is a product of these forces

We can agree to disagree

No, that ignores the fact that the rib is a shear panel.

Thanks, Bob K.
 
Here's a very quick sketch to illustrate the concept.

20ickyf.jpg


In both sketches, the caps have adequate bending stiffness but only have pinned connections to the web or to the mount at the left. The web provides shear stiffness, more or less as I'll describe, but no bending stiffness itself.

In the top sketch, there is very low shear stiffness. It's like a truss without the diagonal members. In every location, the web remains parallel to the support because there's nothing to keep them from collapsing like a parallelogram. Nothing carries the shear force so the caps act separately as unrelated beams with only their own bending stiffness. They carry no axial forces.

The word that describes this is "mechanism" because it moves.

In the bottom sketch, the web has very large shear stiffness and in every location, remains perpendicular to the caps. This permits the caps to carry primarily axial forces since the web carries the shear.

The purpose of the web of the rib is to provide the same sort of stiffness that the diagonal bracing in a wooden truss wing rib provides.

Sorry if I wasn't clear above.

Joe, I'm not trying to say the design isn't okay. It might be. But as this is an important - and obscure - sort of detail, I'm interested in what the load path is. While shear forces usually have smaller numbers than bending moments, here and there,especially at the connections, the stresses do build up and can be important. Also, the stiffness of the shear load path is typically both important and frequently overlooked.

Dave
 
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Here's a very quick sketch to illustrate the concept...

Here's a slightly different sketch that exaggerates the "parallelogramming" effect that David describes:

shear-vs-bending.gif


Now, the reason you'll probably get away with this for a while is that the walls of your tank, assuming that they're aluminum of ~0.050" or so, probably provide enough shear stiffness to transfer loads into the ribs at each end of the tank where you are anchoring it. But that doesn't really fix the problem, all it does is delay it and move it around. What you'll likely see is accelerated fatigue and cracking at the forward flanges of the ribs in the tank area.

Another area of possible concern is that the design of aluminum fuel tanks is somewhat of a dark art. With the flat bottom and top suggested by the cutouts in the ribs, you'll likely see a bunch of the sort of drumming and accelerated fatigue that gave Alfred Scott fits when he was developing tanks for the F.8L Falco. The Sequair website used to have a great article on this topic, but unfortunately it looks like it did not survive the transfer when Scott handed off the Falco kit business.

Edited: Looks like the site was just down for a couple hours while I was looking; it's up now. Here it is:

http://www.seqair.com/skunkworks/FuelSystem/Problems/Problems.html

Thanks again, Bob K.
 
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this is not for anyone to copy

A_06_03_01.JPG


The top angles come off to install the tanks.

A_06_03_04.JPG


There are two ribs one right and one left in the two center rib assemblies.

There is no question that Vans has the resource to design and build wing tanks that would be better than the wing tanks that I built.

I have been designing and testing this design for over two years.

There are ribs in the tanks and the tanks float on rubber in the wing ribs, the tanks are not used to add to the strength of the wing.

I am not a aeronautical engineer, my background is in building engineering and design failure working with Ernst & Whinney now Ernst and Young.

I appreciate all your comments and any concerns that may help find a problem in this design.

I think I have this all covered in my design ( this is not for anyone to copy )

20 gallons of fuel in the cabin is also a big concern.
Thanks All

Joe Dallas
 
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20 gallons of fuel in the cabin is also a big concern.
Thanks All

Joe Dallas

Whatever makes you feel good...

Truth be told, 1 gallon of gasoline in the cabin (or whatever your header tank volume is) is not really a whole lot safer than 20 gallons...it just "sounds" better.

With that said, I don't mean to discourage your efforts towards building something experimental and hopefully better.

Skylor
 
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