Keeping the ball in the middle
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When I was revalidating my PPL some years ago on a 152 I was using more fuel from one tank than the other. I was told by my instructor that this was because I did not have the ball in the middle most of the time - wings not level.
Now, if I fly a 172 on 1 - 2 hour cross country in relatively calm air, mostly with the ball in the middle and little or no rudder required, I still find I sometimes use more fuel from one side than the other (selector on both).
Does this really mean that I have been flying badly? If so, how do I improve?
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"If you keep doing what you've always done, you will keep getting what you've always got"
Now, if I fly a 172 on 1 - 2 hour cross country in relatively calm air, mostly with the ball in the middle and little or no rudder required, I still find I sometimes use more fuel from one side than the other (selector on both).
Does this really mean that I have been flying badly? If so, how do I improve?
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"If you keep doing what you've always done, you will keep getting what you've always got"
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With referance to uneven fuel usage 150/2 172.its not to do with your weight at least not in my view.Might be a bit of out of ballance flight,but not much.Every one of the type I have flown seems to use in preferance fuel from the port tank first,there is a cross feed but it takes a while for it to catch up with demand.Maybe something to do with slightly differing pressure over the port wing,prop slipstream etc.Any other offers???
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fallen eagle - apparently it has something to do with the venting system. There are two reasons why the fuel in a high wing Cessna flows to the engine. The first is gravity, the second is a slight positive pressure. Most Cessna high wings achieve this pressure through the L shaped vent on the left wing. The pressure should be even in both tanks. In order to make sure that it is even (apparently bad things happen if it isn't) Cessna 'link' the top of both tanks from a point at the top of the fuel tanks (Inboard). Because many Cessna tanks are loing and thin (Some 182 LR tanks are about 8 inches high but 7 foot long)and because the wing has some dihedral the equalising vent can be full of fuel rather than air. So - the right tank happens to be feeding the engine, the pressure comes from the left tank which pushes fuel rather than air through the pipes, the right tank remains and indicates full, while the left tank appears to be emptying. Worry not, this situation resolves itself when the left tank empties enough for the connecting vent not to be immersed in fuel.
Hope that helps
Ian
PS The above is sort of a precis from a six page document that the Cessna Pilot Association have put out.
Hope that helps
Ian
PS The above is sort of a precis from a six page document that the Cessna Pilot Association have put out.
Guest
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Many thanks Ian and FE for restoring my confidence. Having about 70 hours in Tiger Moths and about the same in gliders, both many years ago, I didn't think my coordination could be that bad - initially a little rusty perhaps.
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"If you keep doing what you've always done, you will keep getting what you've always got"
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"If you keep doing what you've always done, you will keep getting what you've always got"
Guest
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Hello True North,
You have been told correctly, the airplane does not know the wind is blowing. It doesn't care. The only time YOU care is when performing ground reference manuevers. Downwind turns are ok if ball is centered. And then the wind does not push it at all, just moves with the airmass. Like a boat going across the river, same principle. read "Stick and Rudder". Also if all else is equal the fuel used should be the same between tanks should be the same if wings are level(trim) Or the A/C may prefer one tank over the rest. As far as fixed trim goes, the A/C should be in trim with feet on the floor in the condition it is in most, usually cruise. Exception for instance are tow or jump planes that spend lots of time climbing. Remember the feet move when hands move, ALL THE TIME. ok?
j
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What can you conceive more silly and extravagant than to suppose a man racking his brains, and studying night and day how to fly?
— William Law, 'A Serious Call to a Devout and Holly Life XI,' 1728
[This message has been edited by before landing check list (edited 05 November 2000).]
You have been told correctly, the airplane does not know the wind is blowing. It doesn't care. The only time YOU care is when performing ground reference manuevers. Downwind turns are ok if ball is centered. And then the wind does not push it at all, just moves with the airmass. Like a boat going across the river, same principle. read "Stick and Rudder". Also if all else is equal the fuel used should be the same between tanks should be the same if wings are level(trim) Or the A/C may prefer one tank over the rest. As far as fixed trim goes, the A/C should be in trim with feet on the floor in the condition it is in most, usually cruise. Exception for instance are tow or jump planes that spend lots of time climbing. Remember the feet move when hands move, ALL THE TIME. ok?
j
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What can you conceive more silly and extravagant than to suppose a man racking his brains, and studying night and day how to fly?
— William Law, 'A Serious Call to a Devout and Holly Life XI,' 1728
[This message has been edited by before landing check list (edited 05 November 2000).]
Guest
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Ian Seager describes the C172 tank link - don't I know about this.
On my first flying lesson, pipe developed a leak during the taxi and we had to abandon ship as a small (but worrying) amount of Avgas came through the headlining onto my hair.
I learned about not going near sparks from that!
On my first flying lesson, pipe developed a leak during the taxi and we had to abandon ship as a small (but worrying) amount of Avgas came through the headlining onto my hair.
I learned about not going near sparks from that!
Guest
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True North
I think you have had an excellent response to your question and agree with most of what has been said. However, I cannot belive that your instructor couldn't have shed some light on this issue. Are you sure you're not teaching yourself to fly?
For what it's worth, as an ex Glider pilot I used to be heavy on the feet when flying C150/152. The C150 doesn't have an adjustable trim tab on the rudder ( or at least the ones I am familiar with)and the C152 often get 'adjusted' by students who have forgotten their original walk round brief. However, it takes a pretty meaningful deflection before you would need boot loads of rudder to balance. Make sure your wings are level (equal sky!) then apply rudder as required to balance keeping the wings level.
I used to fly everywhere with one wing down and fight with the Rudder to keep the ball in the middle. Operator error!
Best of luck
I think you have had an excellent response to your question and agree with most of what has been said. However, I cannot belive that your instructor couldn't have shed some light on this issue. Are you sure you're not teaching yourself to fly?
For what it's worth, as an ex Glider pilot I used to be heavy on the feet when flying C150/152. The C150 doesn't have an adjustable trim tab on the rudder ( or at least the ones I am familiar with)and the C152 often get 'adjusted' by students who have forgotten their original walk round brief. However, it takes a pretty meaningful deflection before you would need boot loads of rudder to balance. Make sure your wings are level (equal sky!) then apply rudder as required to balance keeping the wings level.
I used to fly everywhere with one wing down and fight with the Rudder to keep the ball in the middle. Operator error!
Best of luck
Guest
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I've noticed lots of students who fly wing down in the early part of their training.
Students in the left seat would tend to fly R wing low, and those in the right seat (eg trainee instructors) would fly L wing low
Seems to be related to the centerline offset of the seats plus trying to use the cowl/visible sky as the reference for horizontal. They appeared to be trying to achieve an equal ground/sky field of view as they looked from one side to the other.
I suspect that the uneven view from the left or right seat, compared to a centre line seat position is to blame.
In a similar vein is students trying to align heading by using the centre of the cowling instead of a point directly in front of themselves. Again, this is with the offset seating.
One fellow was so adamant that he was flying wings level & heading accurately that I had to line us up dead straight on the runway with him on the centreline then mark the windscreen where a the end of the runways 'touched' + a spot that was aligned with the RWY end centreline.
After that, go flying & see the difference.
I think that if instructors allow students to develop these habits they become ingrained as their primary 'reference' instead the correct one(s)
Students in the left seat would tend to fly R wing low, and those in the right seat (eg trainee instructors) would fly L wing low
Seems to be related to the centerline offset of the seats plus trying to use the cowl/visible sky as the reference for horizontal. They appeared to be trying to achieve an equal ground/sky field of view as they looked from one side to the other.
I suspect that the uneven view from the left or right seat, compared to a centre line seat position is to blame.
In a similar vein is students trying to align heading by using the centre of the cowling instead of a point directly in front of themselves. Again, this is with the offset seating.
One fellow was so adamant that he was flying wings level & heading accurately that I had to line us up dead straight on the runway with him on the centreline then mark the windscreen where a the end of the runways 'touched' + a spot that was aligned with the RWY end centreline.
After that, go flying & see the difference.
I think that if instructors allow students to develop these habits they become ingrained as their primary 'reference' instead the correct one(s)
Guest
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True North
As a followup to the suggestion of trying a plane that needs more rudder, if time & funds permit I recommend spending an afternoon in a glider. Most gliders have no gyro instruments, just the pitot-static and a drift string up front. Because you have no torque, precession or asymetric thrust to deal with you get a very good feel for what the controls alone are doing.
As a followup to the suggestion of trying a plane that needs more rudder, if time & funds permit I recommend spending an afternoon in a glider. Most gliders have no gyro instruments, just the pitot-static and a drift string up front. Because you have no torque, precession or asymetric thrust to deal with you get a very good feel for what the controls alone are doing.
Guest
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Mach_D,
You`re right, I have had an excellent reponse, and I would like to thank everyone for all the helpful replies.
I think I may have mis-represented my instructor a little, however. I am coming to the conclusion that what he meant was "we`re 5 miles from the field after a long flight, so if your foot hurts don`t worry about keeping the ball in the middle. You`re fighting the trim, which is out of whack - once it`s fixed the plane will fly straight. For now, just let it do what it wants." In my ignorance I misunderstood him to mean don`t worry about it EVER, which as so many of you have pointed out, is patent nonsense.
The shock of what I THOUGHT he had said made me forget or doubt everything I thought I knew about aerodynamics and the forces acting on a plane in flight! You have all helped to ease my fears...thank you. (Still planning to do some gliding, though.)
Mach_D, sometimes it feels like I am teaching myself to fly...hour-building for the Commercial!
You`re right, I have had an excellent reponse, and I would like to thank everyone for all the helpful replies.
I think I may have mis-represented my instructor a little, however. I am coming to the conclusion that what he meant was "we`re 5 miles from the field after a long flight, so if your foot hurts don`t worry about keeping the ball in the middle. You`re fighting the trim, which is out of whack - once it`s fixed the plane will fly straight. For now, just let it do what it wants." In my ignorance I misunderstood him to mean don`t worry about it EVER, which as so many of you have pointed out, is patent nonsense.
The shock of what I THOUGHT he had said made me forget or doubt everything I thought I knew about aerodynamics and the forces acting on a plane in flight! You have all helped to ease my fears...thank you. (Still planning to do some gliding, though.)
Mach_D, sometimes it feels like I am teaching myself to fly...hour-building for the Commercial!
