N941WR

N941WR

Legacy Member
Andy Hill said:
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Finally, in a typical RV, you have 2 fuel tanks and normally start on one, taxi out (test that tank's feed), then swap and do run ups prior takeoff on the other (tests other tank). If you eliminate the fuel use on the 2nd tank, you need to ensure that you swap the tanks early enough to feed a reasonable quantity of fuel prior takeoff... wouldn't want it quitting at 100' would we ;)

Andy Hill
RV-8 G-HILZ
RV8tors
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This is not a slam aimed at Andy! It was just a procedure I had never heard of before.

This came up in another thread and I have never heard of this pre-flight procedure before.

Prior to start, I switch to the fullest tank and leave it there until at altitude a half an hour away, when I switch tanks for the first time. Just the way I was taught.

The Theory was that if you switch tanks before takeoff, you might not get all the water or whatever out of either tanks before takeoff. At least with one known good tank, you can always go back to it, if there is a problem with the other tank. In the procedure described above, you might have gunk in both tanks and run into a problem on takeoff.

Thoughts?
 
I'm with you Bill. I would have used the other tank on the previous flight. However, I usually burn 10 gallons before switching tanks. Just my procedure.
 
Checking both tanks in run-up is asking for trouble IMHO. These things will run just long enough to get you in the air if there is a problem with the second tank. Select your tank, start the engine, taxi, run-up and take off. Change tanks at altitude after ever how long you want.

Carbed guys: Just for giggles try this... Turn the fuel selector to off, start up, taxi and perform a run-up. Unless your hangar is a really long way from the runway your engine will still be running when you get to the run-up.
 
Sid Lambert said:
...Carbed guys: Just for giggles try this... Turn the fuel selector to off, start up, taxi and perform a run-up. Unless your hangar is a really long way from the runway your engine will still be running when you get to the run-up.
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I did that during my 1st Phase 1. The idea was to find out how long it would take to run the carb bowl dry. Then make sure your takeoff roll doesn't start until after that length of time. If the engine is still running, then you know your valve is not in the "off" position or on an empty tank.
 
I have a filter and pump in each wing root, and no mechanical pump. I do not have a tank selector valve, just an on/off valve after the "T" junction. Feeding a TBI.

I turn on the second pump as part of the pre-take-off check list. I then do the run-up and take-off on both tanks. My thinking is, if there is a problem with one tank, the other tank is still supplying.

Can anyone see a problem with my procedure?

Sorry for "bushwhacking" your post Bill
 
Do you have check valves installed so you don't cross feed your tanks, should one go dry?
 
Question on Retired Racers setup

Please educate me on what is wrong with both tanks feeding a tee, then parallel pumps (with check valves), then one shut off valve ? I would like to achieve the simplicity of a gravity feed ship, recognizing you need an electric pump and a backup, due to low wing tanks. I read a comment about unporting the pickup on the high tank in a turn. Wouldn't a small orfice address that ?
 
Larry DeCamp said:
Please educate me on what is wrong with both tanks feeding a tee, then parallel pumps (with check valves), then one shut off valve ? I would like to achieve the simplicity of a gravity feed ship, recognizing you need an electric pump and a backup, due to low wing tanks. I read a comment about unporting the pickup on the high tank in a turn. Wouldn't a small orfice address that ?
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If one tank runs dry, that's it. You won't be able to suck fuel out of the other one. You can test this by sucking out of two staws. Pull one out of the glass of water.

L.Adamson
 
Larry DeCamp said:
.... I read a comment about unporting the pickup on the high tank in a turn. Wouldn't a small orfice address that ?
Click to expand...
A coordinated turn will solve that problem because then the fuel will stay in the bottom of the tank, same as if you were straight and level.
 
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