Fuel system thoughts and questions
#1
Thread Starter
Join Date: Feb 2007
Location: Carlsbad,
NM
Posts: 177
Likes: 0
Received 0 Likes
on
0 Posts
Fuel system thoughts and questions
Since it is pretty easy to have issues with cavitation/air bubbles, etc. with long suction lines in our fuel systems, would it not be a good idea to locate the fuel pump close to or even in the tanks? This way the pump would push the fuel instead of pulling it. The advantage I can see doing it this way is the fuel would always be under positive pressure eliminating the cavitation/air bubble problem. Modern cars are plumbed this way with their fuel pumps located in the gas tank. Since I'm new to turbine-powered airplanes, I've been searching through old posts trying to get up to speed on these beasts, and it seems that the fuel systems cause their fair share of grief. I realize that an in-tank pump idea would require a redesign of the pump, but the close-to-the-tank idea seems plausable to me. What are your thoughts?
Thanks,
Luckyflyer
Thanks,
Luckyflyer
#2
My Feedback: (1)
Join Date: Jan 2002
Location: kenilworth , UNITED KINGDOM
Posts: 2,370
Received 0 Likes
on
0 Posts
RE: Fuel system thoughts and questions
If you use 6mm O.D (4mm I.D) pvc tubing up to the pump and make sure all the tank fittings, clunks and tubing are also 4mm I.D you won't go far wrong. The only time I would be happy to have a bore less than 4mm is either when I use a small engine or I have two parallel tanks of the same size feeding a hopper which has a 4mm I.D feed to the UAT.
Jason
Jason
#3
My Feedback: (2)
RE: Fuel system thoughts and questions
I don't see a sumberged pump as practical, and I don't think cavitation is a common issue with large fuel lines, but u may be on to something when u suggest putting the pump next to the tank, eliminating the UAT as a possible cavitator.
One would have to use something more substantial than a simple plug to cap the line used for fueling though !
Interesting idea.
Oops, just thought of a problem. One had best use a rigid UAT, lest the thing cause response lags as it expands/contracts under varied pump pressures.
One would have to use something more substantial than a simple plug to cap the line used for fueling though !
Interesting idea.
Oops, just thought of a problem. One had best use a rigid UAT, lest the thing cause response lags as it expands/contracts under varied pump pressures.
#4
Thread Starter
Join Date: Feb 2007
Location: Carlsbad,
NM
Posts: 177
Likes: 0
Received 0 Likes
on
0 Posts
RE: Fuel system thoughts and questions
ORIGINAL: highhorse
One would have to use something more substantial than a simple plug to cap the line used for fueling though !
One would have to use something more substantial than a simple plug to cap the line used for fueling though !
#5
My Feedback: (2)
RE: Fuel system thoughts and questions
ORIGINAL: luckyflyer
A fill line could be ran directly to the tank.
ORIGINAL: highhorse
One would have to use something more substantial than a simple plug to cap the line used for fueling though !
One would have to use something more substantial than a simple plug to cap the line used for fueling though !
#6
RE: Fuel system thoughts and questions
Most jets have a shut off valve to use in an emergency & there was some discussion in another thread on whether the valve should go on the suction or discharge side of the pump.
The main objection to the valve being on the discharge side of the pump was the valve & fuel lines would be subject to the considerable pressure fuel pumps are capable of generating & the risk of a line or fitting bursting spraying fuel everywhere.
With what you are proposing the entire fuel system would have to withstand this pressure.
As Jason said, a lot of work has gone into the current system & the bugs are pretty well ironed out, lessons learnt the hard way mostly.
But new ideas are always welcome!
Welcome to jets! - John.
The main objection to the valve being on the discharge side of the pump was the valve & fuel lines would be subject to the considerable pressure fuel pumps are capable of generating & the risk of a line or fitting bursting spraying fuel everywhere.
With what you are proposing the entire fuel system would have to withstand this pressure.
As Jason said, a lot of work has gone into the current system & the bugs are pretty well ironed out, lessons learnt the hard way mostly.
But new ideas are always welcome!
Since I'm new to turbine-powered airplanes
#7
My Feedback: (112)
Join Date: Jan 2002
Location: VICTORVILLE,
CA
Posts: 325
Likes: 0
Received 0 Likes
on
0 Posts
RE: Fuel system thoughts and questions
The pressure problem could be solved by adding a by-pass to the shut-off valve, this would return the fuel to the main tank without stressing the system.
#8
My Feedback: (2)
RE: Fuel system thoughts and questions
ORIGINAL: Boomerang1
Most jets have a shut off valve to use in an emergency & there was some discussion in another thread on whether the valve should go on the suction or discharge side of the pump.
The main objection to the valve being on the discharge side of the pump was the valve & fuel lines would be subject to the considerable pressure fuel pumps are capable of generating & the risk of a line or fitting bursting spraying fuel everywhere.
With what you are proposing the entire fuel system would have to withstand this pressure.
As Jason said, a lot of work has gone into the current system & the bugs are pretty well ironed out, lessons learnt the hard way mostly.
But new ideas are always welcome!
Welcome to jets! - John.
Most jets have a shut off valve to use in an emergency & there was some discussion in another thread on whether the valve should go on the suction or discharge side of the pump.
The main objection to the valve being on the discharge side of the pump was the valve & fuel lines would be subject to the considerable pressure fuel pumps are capable of generating & the risk of a line or fitting bursting spraying fuel everywhere.
With what you are proposing the entire fuel system would have to withstand this pressure.
As Jason said, a lot of work has gone into the current system & the bugs are pretty well ironed out, lessons learnt the hard way mostly.
But new ideas are always welcome!
Since I'm new to turbine-powered airplanes
#9
My Feedback: (18)
Join Date: Jul 2002
Location: Tulsa,
OK
Posts: 323
Likes: 0
Received 0 Likes
on
0 Posts
RE: Fuel system thoughts and questions
What we are using currently when done right works perfectly. It is easly to do PM on the system as well as the install is pretty straight forward. I have over 200 flights and never a hickup from fuel delivery. Don't need to re-invent the wheel here. A clean install really makes the differance.
#10
RE: Fuel system thoughts and questions
But the two scenarios are different, right?
Then there's no 'relief', the pump would be pushing against the second tank & the UAT if fitted. The first (main?) tank is, of course, vented. - John.
#11
Senior Member
Join Date: May 2003
Location: NA,
NJ
Posts: 398
Likes: 0
Received 0 Likes
on
0 Posts
RE: Fuel system thoughts and questions
Lots of fuel.... Electricity.....
I keep the pump close to the engine. All electricity well away from the fuel. I rather spend more time dealing with cavitation then with a fire hazard.
I keep the pump close to the engine. All electricity well away from the fuel. I rather spend more time dealing with cavitation then with a fire hazard.
#13
RE: Fuel system thoughts and questions
ORIGINAL: highhorse
Given that most of the cavitation issues mentioned in the recent thread on the topic occur at the UAT...I think the idea has merit, and that someone (else) should give it a try :-)
Given that most of the cavitation issues mentioned in the recent thread on the topic occur at the UAT...I think the idea has merit, and that someone (else) should give it a try :-)
Mike
#14
My Feedback: (2)
RE: Fuel system thoughts and questions
ORIGINAL: BaldEagel
To many ideas on here to know which one you are refering to, I don't get cavitation at the UAT because its in the workshop ever since I took it out and just started using a decent clunk.
Mike
ORIGINAL: highhorse
Given that most of the cavitation issues mentioned in the recent thread on the topic occur at the UAT...I think the idea has merit, and that someone (else) should give it a try :-)
Given that most of the cavitation issues mentioned in the recent thread on the topic occur at the UAT...I think the idea has merit, and that someone (else) should give it a try :-)
Mike