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  #21  
Old 02-21-2018, 02:16 PM
Thunda Down Under Thunda Down Under is offline
 
Join Date: Feb 2018
Location: Mildura.
Posts: 19
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Thanks again Slice, l think I'll try this in the circuit area of my strip and see how it goes.

I had thought of fitting an electric fuel pump on the axillary tank (with in line valve) and just keep topping up the main tank in use.

This would allow the axillary tank to be drained then operate as normal.

I use the extra range to get to (and out) remote areas in central Australia to prospect for gold, so the RV 4 with its low stall and no wheel pants has got all the room for my gear for a few days in the field.
I wonder if anyone over there is doing anything like this, would be good to hear from them.
Thanks again Slice.
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  #22  
Old 02-21-2018, 05:25 PM
Slice Slice is offline
 
Join Date: Aug 2016
Location: Tacoma, WA
Posts: 64
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Quote:
Originally Posted by Thunda Down Under View Post
I had thought of fitting an electric fuel pump on the axillary tank (with in line valve) and just keep topping up the main tank in use.

This would allow the axillary tank to be drained then operate as normal.
It is an option. Van's makes a 4 position fuel selector so I opted to feed direct to the engine thus eliminating the need for an additional pump. It also allows me to start feeding from the aux not long after takeoff and being to shift the CG forward again.

Definitely several ways to go about it. Good luck!
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  #23  
Old 06-03-2019, 12:40 PM
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gmcjetpilot gmcjetpilot is offline
 
Join Date: Jan 2005
Posts: 3,803
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Quote:
Originally Posted by riobison View Post
Why not just function the selector, turn it to the fullest tank and leave it there until safely in the air at altitude and then start changing tanks as needed? Thanks Tim
Tim you are thinking correctly. The one basic rule of thumb is have boost pump on and selector to tank with fuel. Period. Switch as you like otherwise. I am NOT a fan of switching tank back and forth right before take-off. I switch to keep tanks fairly balanced on ground or air... and select the proper tank. As long as there is no big difference in fuel level or imbalance either tank, either tank is proper. I don't adhere to absolute fullest tank.

One way to minimize switching:
1) Select "proper tank", typically fullest.
2) start, taxi and run up, do not switch tank
3) boost pump on, take off
4) Airborne (with sufficient altitude) turn boost pump off.
5) As required or desired to keep balance turn boost on and select opposite tank, boost pump off.

I searched the internet for Piper checklist. Piper being low wing is closest thing to the RV. I saw a wide variation.
One says start on fullest. Then before takeoff "select proper tank". I saw "PROPER tank" not fullest several times.
What does that mean? If the tank difference is small use either tank. This is my technique.

Example L tank 65% and R tank 55% entering pattern on R tank. Switching from R tank you were are on last 30 minutes to L tank make sense for 10%?
Now if you screwed up en-route, R tank was 10% and L tank 50% by all means switch to L tank. I would do that on initial descent not pattern.

Unrelated but the Ted Smith Aerostar (Later Piper Aerostar twin engine, mid wing) I flew had wing and aux tanks. It was complicated. Fuel balance and not running the Aux tank dry before wing tanks was critical. The wings were skinny and you could un-port fuel pickup if too low in double cross feed (bypass Aux tank). If you ran the Aux dry before the wing tank you could also starve the engine. There were a few accidents due to fuel mismanagement. RV' have one engine, one selector, one pump and two tanks. Not that hard.
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Raleigh, NC Area
RV-4, RV-7, ATP, CFII, MEI, 737/757/767

Last edited by gmcjetpilot : 06-03-2019 at 01:27 PM.
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  #24  
Old 06-04-2019, 12:00 AM
Yen Yen is offline
 
Join Date: May 2010
Location: Benaraby Queensland. Australia
Posts: 191
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One advantage of having two separate tanks is when you need to sideslip to lose height.
If you are feeding from both tanks you may have no problem, but if your high wing tank is low on fuel you could have starvation.
Even worse is if you have the two separate tanks and run on the low wing tank. I think that put a Bonanza down a couple of weeks ago. He was too high, slipped to get on the glide slope and the engine failed, causing him to undershoot.
I start after I have observed fuel pressure from the pump on one tank, then turn over to the other tank, taxi and do engine run up with pump off, turn pump on and take off. that proves mechanical and auxiliary pump are working on my carbed engine.
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  #25  
Old 06-06-2019, 12:18 PM
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gmcjetpilot gmcjetpilot is offline
 
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Quote:
Originally Posted by Yen View Post
One advantage of having two separate tanks is when you need to sideslip to lose height.

If you are feeding from both tanks you may have no problem, but if your high wing tank is low on fuel you could have starvation.
Even worse is if you have the two separate tanks and run on the low wing tank. I think that put a Bonanza down a couple of weeks ago. He was too high, slipped to get on the glide slope and the engine failed, causing him to undershoot.

I start after I have observed fuel pressure from the pump on one tank, then turn over to the other tank, taxi and do engine run up with pump off, turn pump on and take off. that proves mechanical and auxiliary pump are working on my carbed engine.
Good point. I wounder what level of fuel (emptiness) and slip would un-port the pickup in an RV. Does anyone one to flight test that?
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RV-4, RV-7, ATP, CFII, MEI, 737/757/767
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