Physics Question

If we ignore the effects of the tail, it will follow path 1. If the tail is not "ignored" then it will follow path 2. Why? The tilt is only giving a force pushing the aircraft to the right. The tail would then "point" the aircraft in its new direction, and rinse repeat.

Think of a helicopter when it banks left/right.. it does not proceed in a circular motion, it continues left/right.
 
If there are no control inputs, and the wings are level to each other ( No deihedral)

Then I would expect a downward turn to the right, not a complete circle, but certainly not option 1 either.
 
Dj_Jestar said:
If we ignore the effects of the tail, it will follow path 1. If the tail is not "ignored" then it will follow path 2. Why? The tilt is only giving a force pushing the aircraft to the right. The tail would then "point" the aircraft in its new direction, and rinse repeat.

Think of a helicopter when it banks left/right.. it does not proceed in a circular motion, it continues left/right.
Click to expand...

But the tilt changes the lift Vector Direction,

We are no longer creating lift straight up, we are creting lift to the top right.
 
From a simplistic view path 1 is correct assuming the only forces are mavity and those developed by the wings, obviously won't happen in reality due the other things we're ignoring.

All you've got is an unbalanced force acting to the right (if the vertical component is cancelled out by mavity).

Edit: I'm not sure on the specific type of curve though.
 
MrRoper said:
But the tilt changes the lift Vector Direction,

We are no longer creating lift straight up, we are creting lift to the top right.
Click to expand...
No, we are creating lift banked to the right.. nothing about top-right at all :)

I'm assuming it is a fixed-wing aircraft in dead-level flight, perfectly trimmed. It is then banked slightly to the right. No other inputs changed. The Tail/Rudder has no effect.

The aircraft will follow a path similar, but not as extreme as, Path #1, and eventually hit the ground anyway :p

For it to follow Path #2 the aircraft must yaw. Which, with the above assumption of the Tail and Rudder having no effect, cannot happen.
 
ordinaryjoe said:
The plane is not increasing/decreasing in altitude
The only forces in play are the lift and mavity
Click to expand...

These are the two critical points.

Certainly not path 1. Maybe the circle... but seeing as it isn't increasing/decreasing in altitude then mavity and the vertical component of lift cancel. We are left with a forward velocity (which will remain constant as there are no other forces) and another force/acceleration component associated with lift.

I'd say it will accelerate along the direction of any lift component not cancelled by mavity. This means path 1 is certainly not correct either (no acceleration).

I'd say a spiral with increasing radius.
 
It's got a fixed forward velocity and a side ways velocity that's increasing with a fixed acceleration due to the unbalanced wing force.
 
Dj_Jestar said:
No, we are creating lift banked to the right.. nothing about top-right at all :)

I'm assuming it is a fixed-wing aircraft in dead-level flight, perfectly trimmed. It is then banked slightly to the right. No other inputs changed. The Tail/Rudder has no effect.

The aircraft will follow a path similar, but not as extreme as, Path #1, and eventually hit the ground anyway :p

For it to follow Path #2 the aircraft must yaw. Which, with the above assumption of the Tail and Rudder having no effect, cannot happen.
Click to expand...

OK so my bad on the terminology!

So we are creating lift banked to the right, which introduces a horizontal element to the lift.

So either we turn, or the reduction in lift just makes us lose height with no course deviation..

I dont see how course 1, is possible, we wont 'sideslip' to the right surley?
 
MrRoper said:
OK so my bad on the terminology!

So we are creating lift banked to the right, which introduces a horizontal element to the lift.

So either we turn, or the reduction in lift just makes us lose height with no course deviation..

I dont see how course 1, is possible, we wont 'sideslip' to the right surley?
Click to expand...
Why not? The craft is not on a rail. Why would it "turn" (yaw)?

Jokester has summed up what I meant.
 
clv101 said:
These are the two critical points.

Certainly not path 1. Maybe the circle... but seeing as it isn't increasing/decreasing in altitude then mavity and the vertical component of lift cancel. We are left with a forward velocity (which will remain constant as there are no other forces) and another force/acceleration component associated with lift.

I'd say it will accelerate along the direction of any lift component not cancelled by mavity. This means path 1 is certainly not correct either (no acceleration).

I'd say a spiral with increasing radius.
Click to expand...

Im with you ;)
 
Actually 1 does assume that the force to the right is acting through the centre of mass of the plane, if it doesn't what the plane will do is travel in a straight line but spinning.
 
bennyB said:
Why? There's no air resistance to create drag, a constant force forwards from the engines will continue to accelerate the plane forwards.
Click to expand...
I think the assumption is that the aircraft is at a fixed forward velocity. I.e. it is not accelerating.
 
Jokester said:
Actually 1 does assume that the force to the right is acting through the centre of mass of the plane, if it doesn't what the plane will do is travel in a straight line but spinning.
Click to expand...
Where would the yaw come from? Or do you mean rolling ala "Do a barrell roll!!!11"? :p
 
Ok my view... Path 1 because:
mavity and the upwards verticle component of the lift cancel (No change in altitude)
The horizontal component of the lift provides an acceleration (to the right in this diagram)
The plane can not twist, as all forces act through the centre of mass (mavity always does, and the lift would have to to counter mavity), so there is nothing to change the direction which the plane faces, and therefore, the horizontal component is always in the same direction.

This would give a parabolic curve (mine isn't an exact diagram, but shows the point) because if we call forward the y axis and sideways the x axis:
y is proportional to t
x is proportional to t squared so t is proportional to root x
Therefore, y is proportional to root x giving the parabolic curve
 
ordinaryjoe said:
The plane can not twist, as all forces act through the centre of mass (mavity always does, and the lift would have to to counter mavity), so there is nothing to change the direction which the plane faces, and therefore, the horizontal component is always in the same direction.
Click to expand...

Why cant the plane twist? surly it can rotate about its three axis?
 
bennyB said:
Why? There's no air resistance to create drag, a constant force forwards from the engines will continue to accelerate the plane forwards.
Click to expand...

Read the question! "The only forces in play are the lift and mavity"

There's no engine, no force forward!
 
bennyB said:
Why? There's no air resistance to create drag, a constant force forwards from the engines will continue to accelerate the plane forwards.
Click to expand...

I said the only 2 forces are the lift and mavity. The engines' thrust is ignored (i.e. considered zero)

MrRoper said:
Why cant the plane twist? surly it can rotate about its three axis?
Click to expand...

Not is all forces act through the centre of mass... It is not possible
 
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