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  #1  
Old 01-08-2018, 07:39 PM
Vansconvert Vansconvert is offline
 
Join Date: Apr 2014
Location: Racine, WI
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Default Extended range fuel tanks

For anyone who has extended range fuel tanks, how are they working out for you? Would you do it again? If they are totally empty, are aerobatics ok?
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  #2  
Old 01-08-2018, 07:56 PM
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Mel Mel is offline
 
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Quote:
Originally Posted by Vansconvert View Post
For anyone who has extended range fuel tanks, how are they working out for you? Would you do it again? If they are totally empty, are aerobatics ok?
They are great. Aerobatics are fine with the tanks empty. Since a complete test program has not been accomplished, Hotel/Whiskey does NOT recommend spins.
There is at least one person who unintentionally did an aerobatic routine with the ER tanks full, but I wouldn't count that as a qualifying test.
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Last edited by Mel : 01-10-2018 at 07:33 AM.
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  #3  
Old 01-08-2018, 08:22 PM
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N941WR N941WR is offline
 
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Location: SC
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There are a lot of threads on ER tanks. Including many different ways to build them in.

There are wing tips that have been turned into tanks. There are outboard leading edges that have been turned into tanks. There are tanks that slide into the lighting holes in the outboard leading edge. There are tanks that fit behind the seats and can be used for fuel or smoke oil, depending on how it is plumbed.

The challenge is how to you plumb them into your system.

I have seen suction pulling fuel from the outboard tanks into the inboard tanks and the only vent being on the outboard tank.

High and low fuel level indicators built into the tanks that automatically transfers the fuel from the outboard tanks to the inboard tanks as the inboard tanks use fuel.

Manually activated electric fuel pumps to move the fuel when the inboard tanks have enough capacity. (Turning on the pumps too soon results in pumping your fuel out the vent line.)

Another option is to use the standard Van's fuel valve and connecting an extra tank into the unused fitting.

My personal favorite would be to use a five-way Andair fuel valve (Left Outboard - Left Inboard - Off - Right Inboard - Right Outboard) and switch the fuel manually.

Try using the search function, you will find a few days worth of reading.
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Old 01-08-2018, 10:20 PM
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Toobuilder Toobuilder is offline
 
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Let's not forget the simplest: just build bigger tanks.
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  #5  
Old 01-08-2018, 10:40 PM
rv7charlie rv7charlie is offline
 
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Bigger tanks can affect acro capability; longer tank will allow fuel to move farther outboard.

RE: "Manually activated electric fuel pumps to move the fuel when the inboard tanks have enough capacity. (Turning on the pumps too soon results in pumping your fuel out the vent line.)" : Here's something I never considered, but one of my friends who's a retired research scientist *did* think consider, and tested. If you're pumping fuel into one of the 'main' tanks with standard fuel venting, the real danger isn't pumping fuel overboard; it's over-pressurizing the tank. As long as it's just air exiting the vent, you're fine, but when fuel hits it, pressure can rise to over 5 psi if you're using a high rate pump. The restriction of 5-6 feet of 3/16" line won't flow fuel fast enough to keep pressure from rising.

FWIW, if you wet the leading edges for extra capacity, you can add quite a bit of fuel 10-15 gal/side) for very little hardware weight gain (not much over 1 lb per side).

Charlie
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  #6  
Old 01-09-2018, 05:34 AM
n816kc n816kc is offline
 
Join Date: Jan 2005
Location: Winter Haven, FL
Posts: 204
Default SafeAir1

I've got the SafeAir1 tanks in my 6. 4 1/2 gallons per side, gravity feed into main tanks. Great for long cross countries and tanking up on cheap fuel. Problem free for 500 hours.
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  #7  
Old 01-09-2018, 08:05 AM
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beechrv9a beechrv9a is offline
 
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Default Ditto for my 9A

Quote:
Originally Posted by n816kc View Post
I've got the SafeAir1 tanks in my 6. 4 1/2 gallons per side, gravity feed into main tanks. Great for long cross countries and tanking up on cheap fuel. Problem free for 500 hours.
They work great after 1 year, although I only have 125hrs on my 9A. My Aux tanks have a small electric pump for each wing which I can activate as capacity in the main tank allows. I have small switches located near the main fuel selector valve with LED indicator bulbs to remind me when activated. Each Aux tank pump takes 16 minutes to transfer to the main tank.
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Last edited by beechrv9a : 01-09-2018 at 08:14 AM.
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  #8  
Old 01-09-2018, 08:21 AM
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Default Procedure for fuel transfer with HW Aviation ER tanks

Quote:
Originally Posted by rv7charlie View Post
RE: "Manually activated electric fuel pumps to move the fuel when the inboard tanks have enough capacity. (Turning on the pumps too soon results in pumping your fuel out the vent line.)" : Here's something I never considered, but one of my friends who's a retired research scientist *did* think consider, and tested. If you're pumping fuel into one of the 'main' tanks with standard fuel venting, the real danger isn't pumping fuel overboard; it's over-pressurizing the tank. As long as it's just air exiting the vent, you're fine, but when fuel hits it, pressure can rise to over 5 psi if you're using a high rate pump. The restriction of 5-6 feet of 3/16" line won't flow fuel fast enough to keep pressure from rising.
My procedure is as follows. I start out on the left main. After 5 gallons as shown on fuel totalizer, I switch to right tank. After 5 gallons, I switch back to left tank and turn on transfer pumps. This transfers the 9 gallons from both ER tanks to the mains at the same time, thereby keeping lateral balance consistent.
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<rvmel(at)icloud.com>
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RV-6 Flying since 1993, 175hp O-320, 3-Blade Catto (since 2003)
Legend Cub purchased 12/2017
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  #9  
Old 01-09-2018, 08:32 AM
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airguy airguy is offline
 
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Quote:
Originally Posted by rv7charlie View Post
FWIW, if you wet the leading edges for extra capacity, you can add quite a bit of fuel 10-15 gal/side) for very little hardware weight gain (not much over 1 lb per side).

Charlie
For the 9A wing, I did exactly that and gained 15.5 gallons per side, at a dry-weight-added cost of 17 pounds total, including transfer pumps, plumbing and wiring. I did the Tuckey-style tank mod with flow-through venting. I removed 5 structural ribs and installed 7 fuel ribs, added the rear baffle, and then the senders and fuel caps, plus transfer pumps and an access panel on each wing to get to them. I almost doubled my fuel capacity for only 17 pounds dry weight added - I thought that was a very good tradeoff.

For the connection between the inboard and outboard, I have dual parallel paths from the sump of the outboard to the top vent position on the inboard. One is a straight flowthrough and the other has a Facet low-pressure pump inline. During normal ops the straight flowthrough will draw fuel from the outboard to the inboard as I burn it from the inboard, and in the event my inboard fuel cap develops a leak and doesn't hold the minor vacuum required I can use the Facet to force it across. If the Facet is running while the inboard is full, the fuel will simply return to the outboard via the other straight-through line, no pressurizing the inboard tank.
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Last edited by airguy : 01-09-2018 at 12:21 PM.
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  #10  
Old 01-09-2018, 03:25 PM
rv7charlie rv7charlie is offline
 
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Sounds reasonable to me; the big issue I mentioned was due to the standard vent line being 5-6 feet of -4 line, while the supply was from a high volume pump through a -6 line.
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