Balancing question?
10-26-2011, 06:08 PM
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Balancing question?
Guys,
I need to balance my jet, the main fuel tank is on the cg and the UAT is about 2 inches in front of the main tank. Should I balance the plane with fuel in the UAT or not? Thanks
Glenn
I need to balance my jet, the main fuel tank is on the cg and the UAT is about 2 inches in front of the main tank. Should I balance the plane with fuel in the UAT or not? Thanks
Glenn
10-26-2011, 06:52 PM
#3
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RE: Balancing question?
Glen, you always want to balance with the UAT full regardless of the location in the plane because the UAT remains full all of the time so the weight of the UAT will never change.
BTW, while balancing with gear down is definitely a rule of thumb, I have seen instructions that say to balance with gear up.
BTW, while balancing with gear down is definitely a rule of thumb, I have seen instructions that say to balance with gear up.
10-27-2011, 08:53 AM
#4
RE: Balancing question?
Agree w/UAT full .. and I'd put the gear in whichever position had the rearward-most CG .. for most planes this will be gear down .. but it could possibly be gear up .. then you have the CG set for the worst case that could occur in flight. I suppose an alternate point of view is to always balance with gear down, since that's the landing config where the speed will be lowest...
Dave
Dave
10-27-2011, 08:56 AM
#5
RE: Balancing question?
I have been told by almost all jet pilots that you balance your jet with a full UAT. I think and know that this is a dangerous practice. The weight of the fuel/oil mixture is almost 1 oz per oz of fuel. This means that you are balancing your jet with almost ½ a pound of fuel that may not always be there. Every time I have seen a turbine run out of fuel the UAT is sucked dry. This means that when you are in the worst position during a flight ( you run out of fuel) your jet (witch is now a glider and not a very good one) you may be tail heavy. Whether you are balancing a ½ control line airplane or a 747 you never balance it with usable fuel in it…..
10-27-2011, 10:44 AM
#8
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RE: Balancing question?
Excellent point Gary. I will take the 4 ounces of weight where ever it is as this is the most consistent flight orientation. I think all of the jet pilots who do this on a regular basis consider the UAT fuel unusable. We sure don't like to use it and when we do, normally we aren't very happy about it. Gear config per manufacturer recommendations or as stated above, most rearward CG location.
10-27-2011, 12:42 PM
#9
RE: Balancing question?
Personally i like to balance with the UAT full for the peace of mind that i can shift the UAT and balance without the necessity of dead weight (that's a biggie in my book). i know occasionally I'm gonna have the left stick in the FUN position too long and suck the UAT dry and flame out, but it's never been a problem of a major CG shift when it happens and i've had them tucked in the nose and in the tail on different models to achieve balance. most airframes that 4oz really doesn't make that much difference. YMMV
10-27-2011, 12:49 PM
#10
RE: Balancing question?
ORIGINAL: proline8000
I have been told by almost all jet pilots that you balance your jet with a full UAT. I think and know that this is a dangerous practice. The weight of the fuel/oil mixture is almost 1 oz per oz of fuel. This means that you are balancing your jet with almost ½ a pound of fuel that may not always be there. Every time I have seen a turbine run out of fuel the UAT is sucked dry. This means that when you are in the worst position during a flight ( you run out of fuel) your jet (witch is now a glider and not a very good one) you may be tail heavy. Whether you are balancing a ½ control line airplane or a 747 you never balance it with usable fuel in it…..
I have been told by almost all jet pilots that you balance your jet with a full UAT. I think and know that this is a dangerous practice. The weight of the fuel/oil mixture is almost 1 oz per oz of fuel. This means that you are balancing your jet with almost ½ a pound of fuel that may not always be there. Every time I have seen a turbine run out of fuel the UAT is sucked dry. This means that when you are in the worst position during a flight ( you run out of fuel) your jet (witch is now a glider and not a very good one) you may be tail heavy. Whether you are balancing a ½ control line airplane or a 747 you never balance it with usable fuel in it…..
Actually Jet A is around 6.75 Lbs / Gal (Varies with Temperature) 
, so that 4 Fluid Oz UAT would hold approximately 3.38 oz of liquid weight + weight of the UAT, not quite a 1/2 Lb I agree with the rest I always balance with a full UAT
10-27-2011, 01:27 PM
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RE: Balancing question?
ORIGINAL: proline8000
I have been told by almost all jet pilots that you balance your jet with a full UAT. I think and know that this is a dangerous practice. The weight of the fuel/oil mixture is almost 1 oz per oz of fuel. This means that you are balancing your jet with almost ½ a pound of fuel that may not always be there. Every time I have seen a turbine run out of fuel the UAT is sucked dry. This means that when you are in the worst position during a flight ( you run out of fuel) your jet (witch is now a glider and not a very good one) you may be tail heavy. Whether you are balancing a ½ control line airplane or a 747 you never balance it with usable fuel in it…..
I have been told by almost all jet pilots that you balance your jet with a full UAT. I think and know that this is a dangerous practice. The weight of the fuel/oil mixture is almost 1 oz per oz of fuel. This means that you are balancing your jet with almost ½ a pound of fuel that may not always be there. Every time I have seen a turbine run out of fuel the UAT is sucked dry. This means that when you are in the worst position during a flight ( you run out of fuel) your jet (witch is now a glider and not a very good one) you may be tail heavy. Whether you are balancing a ½ control line airplane or a 747 you never balance it with usable fuel in it…..
First, NEVER, plan or time your flight that close that you may get into the UAT and ALWAYS balance with the UAT full
10-27-2011, 04:51 PM
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RE: Balancing question?
on a few of my planes i have even balanced them with fuel in the main tank ,,after a dozen flights i take the least amount left in the tank do another cg check and if i can take more weight out ,no dead stick landings if fro some reason my timer is not started i land early,,seems to me most of the swept wing jet have a forgiving cg
