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How much space in wing roots?

High_Flyer

High_Flyer

Well Known Member
I am installing a Andair gascolator in each wing root of my RV-7, similar to this picture from Andair :

But I have not fitted the wings yet, and I'd like to ask how much space there is between the side of the fuselage and the fuel tank in the wing root?

Here are 2 pictures to give you an idea of my setup:

Side view:


Top view:


This setup takes 2.7 Inches measured from the fuselage side to the outmost point of the gascolator as seen on the above picture. Is this too much or do I have sufficient space there to keep it as it is?
I plan to make an opening in the bottom of the wing root fairing (maybe a small hinged flap) to be able to purge the gascolator.
Your input would be very welcome, thanks.

Alain.
 
Alain,

I did exactly what you're planning, as have others. I'm not to the flying stage yet but can say it all fits with careful planning and measuring. I even included a shutoff valve upstream of the gascolator so the fuel can be shut off to remove the bowl without losing too much fuel. Send me your email and I will send some pictures.

I doubt you will need a door on the bottom to drain fuel from the bottom of the gascolator. Just make a hole in the wing root fairing when its all done.

Bevan
 
Last edited:
email

Bevan said:
Alain,

I did exactly what you're planning, as have others. I'm not to the flying stage yet but can say it all fits with careful planning and measuring. I even included a shutoff valve upstream of the gascolator so the fuel can be shut off to remove the bowl without losing too much fuel. Send me your email and I will send some pictures.

I doubt you will need a door on the bottom to drain fuel from the bottom of the gascolator. Just make a hole in the wing root fairing when its all done.

Bevan
Click to expand...


My email alainvanseveren(at)gmail.com
replace (at) with @.
Thank you.
Alain.
 
Alain,

Re: shut-off valve, in case you consider this, check carefully what your regulations are in France. My research found that in the UK it is not permitted to have a valve in the fuel system that cannot be controlled from the cockpit.

Steve
 
Done that very thing, but it requires very careful planning. The two sides will be different since the gascolator is one-directional. Use an extended drain fitting to reach through a hole in the gap fairing. Don't forget to allow room to route the vent line amongst all the other spaghetti. You don't need a shut-off valve if you fly out most of the tank's fuel.

John Siebold
 
RV7ator said:
The two sides will be different since the gascolator is one-directional.
John Siebold
Click to expand...

Not so if you plan ahead before purchasing. Andair do left-to-right flow and right-to-left flow gascolators. It is one of the options on their website online purchasing system. In fact the Andair image above shows this.

Personally, I have gone for just one gascolator in the right wing root. It is downstream from the fuel selector, i.e. the lines come in from the tanks to the selector then one line back out to the wing root, through the gascolator, then back to the centreline and forward to the firewall. This provides for fuel shut-off for gascolator inspection without extra shut-off valves in the wing root at the cost of a little extra length in the fuel lines. I went this way as I did not want the gascolator positioned firewall forward.

Steve
 
Gascolators

Thanks for the replies.

RV7ator said:
Done that very thing, but it requires very careful planning. The two sides will be different since the gascolator is one-directional. Use an extended drain fitting to reach through a hole in the gap fairing. Don't forget to allow room to route the vent line amongst all the other spaghetti. You don't need a shut-off valve if you fly out most of the tank's fuel.

John Siebold
Click to expand...

I have a "regular" gascolator and one "reverse flow". This allows the same setup in each wing root.

shuttle said:
Alain,

Re: shut-off valve, in case you consider this, check carefully what your regulations are in France. My research found that in the UK it is not permitted to have a valve in the fuel system that cannot be controlled from the cockpit.

Steve
Click to expand...

I didn't think about fuel flowing out when checking the filter if fuel is in the tank... I'll have to do some reaserch about this. I don't like the idea of having a valve in the wing root that will be out or reach, and I don't even know if that is allowed in the French regulation.

But my main question has not been answered: how much space is there in the wing root area between the tank and the fuselage??

Alain.
 
about this much...

plenty of room... you don't have to reverse flow either.

YjR1uWPj.jpg
 
Don't try this on a -9; there only about half that much space on mine and the bottom wing skin overlaps the bottom of the fuse, so as to Pete's point, you'd never get that bowl off.
 
IIRC, the wing skin overlap is behind the spar. This space is ahead of the main spar. The wing root cover strip allows access to top and bottom.
I don't have measurments, but I located gascolator and boost pump here. The space tapers a bit with the fuselage sidewall. Plan for wrench space, too.
Roger
 
Manage the fuel for inspection...

It is something to consider Pete. I manage the fuel in prep for inspection and start with one tank about empty at annual... During wheel work when the other wing is jacked you can empty the bowl dry. For the other tank you just have to drain it... By raising the tail and jacking the other wing you don't have to drain all the way and can use a siphon at the fill rather than pulling the drain plug... either way is no big deal unless the tank has a lot in it.
 
Draining fuel tank

[email protected] said:
It is something to consider Pete. I manage the fuel in prep for inspection and start with one tank about empty at annual... During wheel work when the other wing is jacked you can empty the bowl dry. For the other tank you just have to drain it... By raising the tail and jacking the other wing you don't have to drain all the way and can use a siphon at the fill rather than pulling the drain plug... either way is no big deal unless the tank has a lot in it.
Click to expand...

So for you this is not really a problem?...
May I ask in your setup about what fuel quantity does the tank need to be in order to avoid fuel flowing when servicing the gascolator? Looking at what height my gascolators are compared to the fuel tanks I would guess about half tank...
I thought that in worst case I can drain the tank in a big jerrycan, service the gascolator and put the fuel back in the tank. Not ideal but doable isn't it?

Thanks again for all the inputs here.

Alain.
 
Why..........

Not really needed.

However if you want to buy great British products - crack on !!!

:D
 
nice fuel filters with easy access...

Mike, they function as fuel filters with easy access outside of the cabin.

Alain, look at the bowl inlet elevation and expect that the tank has to be below that level to break the siphon flow... depends on where you mount them but it is not an issue; just something to be aware of.
 
mike newall said:
Why..........

Not really needed.

However if you want to buy great British products - crack on !!!

:D
Click to expand...

By doing this way I have independant fuel filtering for each tank before the fuel selector and pump. OK fuel filters very very rarely get blocked but just in case if it happens it's just a matter of switching fuel tanks to restore the flow of fuel to the engine. With a single filter after the selector if it gets blocked not good... we have seen tank sealant being degraded to the point of floating in the tank and if that goes into the fuel line it would definitely block at least the filter. And I'm sure there are other bad things that could have the same result.
And by installing the gascolators in the wing root it is very easy acces for maintenance after removal of the root fairings, and an additional water trap for each tank that is easy to drain before each flight.


[email protected] said:
Mike, they function as fuel filters with easy access outside of the cabin.

Alain, look at the bowl inlet elevation and expect that the tank has to be below that level to break the siphon flow... depends on where you mount them but it is not an issue; just something to be aware of.
Click to expand...

Yes that's what I looked at and I think in my setup it will be about half tank or so.

Alain.
 
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