Fuel crossfeed time
Thread Starter
Joined: Nov 2007
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From: Turning outbound
Fuel crossfeed time
Hi there
Can anyone tell me how to time the duration to crossfeed from one tank to the other?Is there any specific formula for that?Any help will be much appreciated
Can anyone tell me how to time the duration to crossfeed from one tank to the other?Is there any specific formula for that?Any help will be much appreciated
Joined: Feb 2009
Posts: 945
Likes: 445
From: Austria
Ok, I´ll bite.
You first add the fuel flow per hour of all the engines You intend to feed from the tank in question. Let me call this figure FF [kg/h] (substitute mass units as required).
Then You determine how much fuel You want burnt off the tank. Let me call that amount M [kg].
The time required to burn up M, assuming no power changes occur in the meanwhile, will be:
M divided by FF equals time required [h]. Multiply this with 60 to achieve the minutes required.
Of course, if You have no CrossFEED, but a CrossFILL installed with no published rate (as in the DH8), there is no real substitute for keeping an eye on the pumping process...
You first add the fuel flow per hour of all the engines You intend to feed from the tank in question. Let me call this figure FF [kg/h] (substitute mass units as required).
Then You determine how much fuel You want burnt off the tank. Let me call that amount M [kg].
The time required to burn up M, assuming no power changes occur in the meanwhile, will be:
M divided by FF equals time required [h]. Multiply this with 60 to achieve the minutes required.
Of course, if You have no CrossFEED, but a CrossFILL installed with no published rate (as in the DH8), there is no real substitute for keeping an eye on the pumping process...
Joined: Mar 2002
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From: Seat 1A
a CrossFILL installed with no published rate (as in the DH8), there is no real substitute for keeping an eye on the pumping process...
Last edited by Capn Bloggs; 23rd January 2013 at 22:25.
Joined: Jul 2006
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From: coming to a bar near you
Making this way too hard.
Open the crossfeed and when the tanks are balanced, close the crossfeed.
Done.
You don't crossfeed a tank to the other tank but you crossburn/crossfeed from tank to engine. ie, buring 2 tanks to 1 engine. (For simplicity, I assume it is a 2 engine a/c)
Open the crossfeed and when the tanks are balanced, close the crossfeed.
Done.
You don't crossfeed a tank to the other tank but you crossburn/crossfeed from tank to engine. ie, buring 2 tanks to 1 engine. (For simplicity, I assume it is a 2 engine a/c)
Last edited by thedude1; 24th January 2013 at 03:25.
Joined: Feb 2009
Posts: 945
Likes: 445
From: Austria
Thedude1,
this is type dependent actually. A Crossfeed will allow feeding an engine with the contents of the other engines dedicated tank - this seems to be the more common option (used on F70/100 and apparently many other jets), while a Crossfill system will use some pumps (on the DH8, the auxiliary fuel pumps that are run during approach/takeoff) to pump fuel from one tank to another; the engines will always be fed from their own tanks.
Now in case of an engine failure, the Crossfeed on the Fokker was the easiest thing imaginable to use - just open the valve and leave everything else as it was; no need to worry about imbalance any more. The Crossfill on the other hand seems designed to provide the crew with more workload (like many other little details on the Dash) - You will need to manually transfer fuel from the dead engines tank to the live one every so often, minding the imbalance Yourself.
this is type dependent actually. A Crossfeed will allow feeding an engine with the contents of the other engines dedicated tank - this seems to be the more common option (used on F70/100 and apparently many other jets), while a Crossfill system will use some pumps (on the DH8, the auxiliary fuel pumps that are run during approach/takeoff) to pump fuel from one tank to another; the engines will always be fed from their own tanks.
Now in case of an engine failure, the Crossfeed on the Fokker was the easiest thing imaginable to use - just open the valve and leave everything else as it was; no need to worry about imbalance any more. The Crossfill on the other hand seems designed to provide the crew with more workload (like many other little details on the Dash) - You will need to manually transfer fuel from the dead engines tank to the live one every so often, minding the imbalance Yourself.
