Banking leaking

Question to Carburator gurus. MS MA3 A leaks fuel into the airbox when carb is banked or pitched about 45 * or more . Just about to remount the carb on engine and noticed this when testing it prior to . Seems not leaking when level.
I had replaced the needle, checked the floats and are ok as does seat .What are prime suspects and what do I need to replace?

Check the float level.

I would expect it to leak if tipped over 45* while not in motion. It is designed to run in the level position and can only accommodates a moderate amount of rotation in any direction. The plane banking 45* in the air is very different than what you did on the ground, assuming your not 0 G. In the airborne case, the fuel is still generally level with the carb bowl even though the carb is at a large angle relative to the horizon (gravity is no longer the only G force). Next time you are up, hold a glass of water during a 45* turn and observe.

Larry

Now just hold on a minute, Larry

I was told I could suspend a nut on a thread from the ceiling of my aircraft and even in the clouds I would always know where "down" was, without those fancy gyros.

You mean they lied to me?

Bill Boyd said:

I was told I could suspend a nut on a thread from the ceiling of my aircraft and even in the clouds I would always know where "down" was, without those fancy gyros.

You mean they lied to me?

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That darn physics stuff seems to trip up so many of our internet pontificators.

std slip indicator is just a bubble level with more curvature; Kind of proves the point, though I did get the sarcasm. More for those challenged with physics. I know many land bound folks struggle to understand horizontal lift and it's effect on gravitational forces. Put the same slip indicator in a sailboat and it becomes an inclinometer; as no horizontal lift is in play.

Larry

Carb

The Marvel carbs have a history of the float rubbing/sticking on the side of the float cavity.

I follow your logic on the gravity effect - but is not the G effect in play only if you are banked AND holding altitude - but there are times when you are steeply banked ( let's say ovr 45*) when there is no, or very little, G force such as a decending turn or perhaps a sideslip for examples.

It's a matter of flying coordinated that will keep it from leaking.

rv6aviator said:

I follow your logic on the gravity effect - but is not the G effect in play only if you are banked AND holding altitude - but there are times when you are steeply banked ( let's say ovr 45*) when there is no, or very little, G force such as a decending turn or perhaps a sideslip for examples.

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A carburetor requires positive G to function. So if an engine with a carburetor is still running there is some level of positive g (even .25 g’s is enough)
A descending steep turn doesn’t put you at 0G, it just puts you at less g’s than you would have if you were level. In fact it’s still probably higher than 1G just not the full value that you would have if you were in a level 45° bang turn. A carburetor will leak fuel if tilted beyond a specific point when not in flight but I don’t know what that angle is.
As long as you can confirm that the fuel leaking out isn’t coming out along the split line between the top and bottom half of the car body, I don’t think you have a problem.

Thank you all gentlemen. The learning never stops - and that's a good thing.

rv6aviator said:

I follow your logic on the gravity effect - but is not the G effect in play only if you are banked AND holding altitude - but there are times when you are steeply banked ( let's say ovr 45*) when there is no, or very little, G force such as a decending turn or perhaps a sideslip for examples.

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Anything above 0 G is a G force. You'll know when you are at 0 G, as you then need belts to keep you in your seat. Look for a video of the floating pencil trick in an airplane (my little one used to love that). The issue here is WHERE the G force is pulling. Straight and level, the 1G is gravity. As you turn the plane at a 45* bank, the wings are creating a component of horizontal lift and therefore G force. This balances with gravitational forces and keeps the G force toward the belly of the plane and not the ground reference. This is why we need a gyro instead of an inclinometer to determine attitude.

Larry

lr172 said:

Anything above 0 G is a G force. You'll know when you are at 0 G, as you then need belts to keep you in your seat. Look for a video of the floating pencil trick in an airplane (my little one used to love that). The issue here is WHERE the G force is pulling. Straight and level, the 1G is gravity. As you turn the plane at a 45* bank, the wings are creating a component of horizontal lift and therefore G force. This balances with gravitational forces and keeps the G force toward the belly of the plane and not the ground reference. This is why we need a gyro instead of an inclinometer to determine attitude.

Larry

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The wings don't create "horizontal lift" or vertical lift or anything like that...they create *lift*, which is a force which acts in a single direction (generally speaking, perpendicularish to the airflow over the wing). This can be represented as a vector which, when put into the normal coördinate system, can be *decomposed* into a horizontal and a vertical *component*.

The horizontal component does NOT "balance gravity"...the vertical component (in the X-Y plane) counteracts the negative force of gravity. The horizontal component also does not, by itself, "keep the G force toward the belly". The entire lift vector does this, and technically it's due to centripetal acceleration (and not the fictitious centrifugal force that is so commonly though of).

This is basic airmanship.

RV7A Flyer said:

The wings don't create "horizontal lift" or vertical lift or anything like that...they create *lift*, which is a force which acts in a single direction (generally speaking, perpendicularish to the airflow over the wing). This can be represented as a vector which, when put into the normal coördinate system, can be *decomposed* into a horizontal and a vertical *component*.

The horizontal component does NOT "balance gravity"...the vertical component (in the X-Y plane) counteracts the negative force of gravity. The horizontal component also does not, by itself, "keep the G force toward the belly". The entire lift vector does this, and technically it's due to centripetal acceleration (and not the fictitious centrifugal force that is so commonly though of).

This is basic airmanship.

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I was trying to keep it simple and understandable. Most of the PPL instruction uses the simplified concepts of balancing vertical lift (keeping you at an altitude) and horizontal lift (making the airplane move horizontally) to help those without physics training to understand the concepts. Goes all the way back to the famous "stick and rudder" text that helped A LOT of people understand what the airplane was doing and why. By referencing these forces to the horizon, the average guy gets it and can understand the risks of trading one for the other. Yes, I understand that lift and G forces are not that simple, but was trying to make it understandable. Once you start talking about lift vectors and centripetal forces, the average person tunes out, which is why it is not taught that way to most pilots, though I suspect the military does teach it that way. I would argue that basic airmanship is about understanding what the plane is doing at any moment, along with why it is doing it and what trade offs have occurred. I doubt more than 10% of pilots know what centripetal force is or how it relates to what their plane is doing at any moment in time. Bob hoover taught himself advanced flight maneuvers and become one of the most famous examples of good airmanship, so I don't believe that knowing the underlying physics is critical to good airmanship; Just the cause and effect relationship.

lr172 said:

I was trying to keep it simple and understandable. Most of the PPL instruction uses the simplified concepts of balancing vertical lift (keeping you at an altitude) and horizontal lift (making the airplane move horizontally) to help those without physics training to understand the concepts. Goes all the way back to the famous "stick and rudder" text that helped A LOT of people understand what the airplane was doing and why. By referencing these forces to the horizon, the average guy gets it and can understand the risks of trading one for the other. Yes, I understand that lift and G forces are not that simple, but was trying to make it understandable. Once you start talking about lift vectors and centripetal forces, the average person tunes out, which is why it is not taught that way to most pilots, though I suspect the military does teach it that way. I would argue that basic airmanship is about understanding what the plane is doing at any moment, along with why it is doing it and what trade offs have occurred. I doubt more than 10% of pilots know what centripetal force is or how it relates to what their plane is doing at any moment in time.

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I get the pedagogy here, but stating that "horizontal lift" "balances gravity", and somehow that keeps things pointed towards the floor???

I don't know about your instruction, but mine certainly included an explanation of the lift vector (along with the math that explained why you pull more g's in a steeper bank). Again, that is, to my knowledge, a fundamental part of PPL training.

I'll agree that most people, pilots included, don't understand centripetal ACCELERATION and the (fictitious) CENTRIFUGAL force. But every pilot should understand the concept of a lift vector.

RV7A Flyer said:

I get the pedagogy here, but stating that "horizontal lift" "balances gravity", and somehow that keeps things pointed towards the floor???

I don't know about your instruction, but mine certainly included an explanation of the lift vector (along with the math that explained why you pull more g's in a steeper bank). Again, that is, to my knowledge, a fundamental part of PPL training.

I'll agree that most people, pilots included, don't understand centripetal ACCELERATION and the (fictitious) CENTRIFUGAL force. But every pilot should understand the concept of a lift vector.

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I agree that I should have stated vertical lift instead of gravity. I still would argue that most pilot are taught about trading vertical lift for horizontal lift and not familiar with lift vector, though understand it conceptually. They probably also understand that more vertical lift is required during the trading to maintain altitude, though probably just think of it as stick pull.

lr172 said:

I agree that I should have stated vertical lift instead of gravity. I still would argue that most pilot are taught about trading vertical lift for horizontal lift and not familiar with lift vector, though understand it conceptually. They probably also understand that more vertical lift is required during the trading to maintain altitude, though probably just think of it as stick pull.

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I'm not sure YOU understand this. Vertical lift is not *traded* for horizontal lift to maintain altitude during a turn. The *total lift* is *increased*, which causes an increase in both the vertical AND the horizontal component.

I, for one, was never taught anything about "trading" one lift component for another. I was taught, and I think most pilots are or should be, about the idea of *total lift* and how it can have the two components. And I was taught nearly 30 years ago, so this isn't a new instructional technique.

RV7A Flyer said:

…....they create *lift*, which is a force which acts in a single direction (generally speaking, perpendicularish to the airflow over the wing). This can be represented as a vector which, when put into the normal coördinate system, can be *decomposed* into a horizontal and a vertical *component*.
.

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I totally agree with what you said. But the FAA itself has muddied the water. In their publications, wrt an airplane in level flight, they do not identify ‘lift’ as the total force acting in a single direction. Rather, they call the vertical component ‘lift’, and the rearward pointing component ‘induced drag’. Of course when they use Bernouli’s law to calculate the total force they call that ‘lift’, too. Little wonder there’s confusion.

BobTurner said:

I totally agree with what you said. But the FAA itself has muddied the water. In their publications, wrt an airplane in level flight, they do not identify ‘lift’ as the total force acting in a single direction. Rather, they call the vertical component ‘lift’, and the rearward pointing component ‘induced drag’. Of course when they use Bernouli’s law to calculate the total force they call that ‘lift’, too. Little wonder there’s confusion.

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Oh, now you've done it....gone and added a 3rd dimension to the analysis .

I think since you can't normally do much about the component in the "rear" direction, it kind of gets ignored, other than academically in explanation of drag (induced + parasitic). But, yes, we do live in a 3-dimensional world, so you really should decompose the lift vector into all 3 axes.

RV7A Flyer said:

I'm not sure YOU understand this. Vertical lift is not *traded* for horizontal lift to maintain altitude during a turn. The *total lift* is *increased*, which causes an increase in both the vertical AND the horizontal component.

I, for one, was never taught anything about "trading" one lift component for another. I was taught, and I think most pilots are or should be, about the idea of *total lift* and how it can have the two components. And I was taught nearly 30 years ago, so this isn't a new instructional technique.

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At any given speed, AOA and air density, there is a fixed amount of lift a wing produces. when level, all that lift goes upward, fighting gravitational forces. once you bank, the wing's lift amount is the same, but less of it is fighting gravity and is instead also moving in the horizontal plane and fighting inertial forces. Lift vector no longer parallel to gravitational forces. Banking an airplane does not increase the amount of lift that the wing produces. Now, if you pull back on the stick, as you were taught, more lift IS created at the expense of forward speed (i.e. not the same speed / air density relationship). It is not producing more lift due to being in a bank, but instead due to the increased angle of attack caused by ele change. This is why your IFR instructor told you to increase power in a turn if you wanted to do a constant speed/altitude turn; You are trading airspeed for total lift without more thrust added. As you know, lift is lift and the wing doesn't care were it is relative to the horizon, however, when it comes to maintaining altitude a certain amount of vert component lift is required to fight gravitational forces which are always perpendicular to the earths surface. It is critical to understand both, as vert lift has to balance with gravity and hor only with inertial forces.

Whenever you bank, you trade some of the vert component for hor, as shown in your graphics. This is why you pull back on the stick, to increase total lift, so that the vert component is still enough to maintain altitude.

I'll get off the podium now and just agree to disagree.

Larry