Top E Planes

[BnZs]

The two important factors in a zoom climb are power/weight and thrust/weight. I know this because Mace said so :-) Plus eventually the ability to hold the thing steady as the speed bleeds off.

[Badboy]

If one dropped a BB and a cannon ball at the same time from the tower of Pisa, the BB and the cannon ball would both hit the ground at the same time.

Not true, they would hit the ground at different times and the difference would be due to their mass.

If you write the equation of motion for the BB and the cannon ball you start with Newton's law:

    f = m a

The force f downwards is gravity and is equal to mg and the force upwards caused by air resistance is -d giving

   mg-d = ma

then divide both sides by m gives

   a = g - d/m

This means that for the same drag the heavier object will have greater acceleration to the ground.


In a zoom climb similar reasoning applies, so starting with Newton's law again:

  f = ma

this time the gravity and drag both act in the same direction, so we have:

  -mg-d = ma

dividing both sides by mass gives

  -a = g + d/m

This shows that ballistically the heavier object will have smaller deceleration and thus zoom higher.

The situation is more complicated when thrust is included, but leaving thrust out does help clarify the effect of mass and gravity.

Regards

Badboy

[Karnak]

This shows that ballistically the heavier object will have smaller deceleration and thus zoom higher.

The situation is more complicated when thrust is included, but leaving thrust out does help clarify the effect of mass and gravity.

Regards

Badboy

The problem is that many people expect more exaggerated differences than they get.  A P-47 initiating a zoom climb from 300mph will end up higher than an A6M doing the same, but not all that much higher.  People often seem to expect the P-47 would double, or better, the A6Ms zoom climb.

[BnZs]

The problem is that many people expect more exaggerated differences than they get.  A P-47 initiating a zoom climb from 300mph will end up higher than an A6M doing the same, but not all that much higher.  People often seem to expect the P-47 would double, or better, the A6Ms zoom climb.

Weight/drag ratio (ballistic) is a factor, but I think it was Mace again who explained on a thread that in airplane zoom performance it is a minor factor compared to thrust/weight and thrust/drag ratio.

In my tests, from going on the deck 400, you can expect to get back 6000 some odd feet. Held true with every plane tested. The best was the P-38, which got 7K purely because its can point it's nose at the sky longer because of no net torque.

IIRC, the section on energy fighting in "Fighter Combat" by Shaw suggests having at least a 100mph speed advantage to safely deny the lower energy bandit the ability to zoom with you.

[FLOOB]

It's because gravity is proportional that the hammer and feather fall together in a vacuum.

Please explain.

[FLOOB]

Not true, they would hit the ground at different times and the difference would be due to their mass.

If you write the equation of motion for the BB and the cannon ball you start with Newton's law:

    f = m a

The force f downwards is gravity and is equal to mg and the force upwards caused by air resistance is -d giving

   mg-d = ma

then divide both sides by m gives

   a = g - d/m

This means that for the same drag the heavier object will have greater acceleration to the ground.


In a zoom climb similar reasoning applies, so starting with Newton's law again:

  f = ma

this time the gravity and drag both act in the same direction, so we have:

  -mg-d = ma

dividing both sides by mass gives

  -a = g + d/m

This shows that ballistically the heavier object will have smaller deceleration and thus zoom higher.

The situation is more complicated when thrust is included, but leaving thrust out does help clarify the effect of mass and gravity.

Regards

Badboy

Yes because of air resistance the BB falls slower but I was referencing galileos experiment to show that the effects of gravity on an object aren't proportional to the objects mass.

[wpeters]

Yes because of air resistance the BB falls slower but I was referencing Galileo experiment to show that the effects of gravity on an object aren't proportional to the objects mass.

That only works if the bbs and cannon are starting at the smae place at at the same time.   Take a .243 55grain shell. It has a muzzle velocity of 3500fps where as a 50 bmg has a muzzle velocity of around 2100-2300 fps.  The fact that the 50 around 800 grains is the determing factor that it will go farther in the verticle.


Same thing as throwing a tennis ball versus a baseball. The baseball will go farther due to the fact of more mass.   


Galileo's expermint was dropping the objects from the same height. That is the determing factor.


As to the fact that you need 100mph over adversary is how well and how long he can hang on his prop. As it has been pointed out already. Even if you have 100mph advantage over the P-38 he is still going to hang under you longer and will be able to get a lucky shot off in the least.

[FLS]

Please explain.

The force of Gravity is a constant multiplied by the mass of an object. The greater the mass the more force.


Badboy if we consider air resistance don't we have to consider the different coefficients of drag in different aircraft too?

[Mongoose]

P-38 has excellent energy retention,

  Especially when I am trying to slow down to land.   

[Mongoose]

Not true, they would hit the ground at different times and the difference would be due to their mass.

  Nope, they would hit at different times, but not because of their mass, because of the difference in air resistance.  Acceleration due to gravity is 32ft per second, regardless of mass.  But greater air resistance will cause one to fall slower.

  If you take to objects, with differing mass, but equal air resistance, they will both fall at the same speed.  If you have a 500 pound weight, and a 50 pound weight, and both have the same air resistance, and you drop both from the same height at the same time, they will both hit the ground at the same time.  Acceleration due to gravity is the same for both.  Drag due to air resistance is what would make one fall faster.

  Now, let's say these two weights are airplanes with identical aerodynamic characteristics.  The 500 pound airplane and the 50 pound airplane both dive straight towards the ground.  As long as they have identical drag, they both dive side by side at the same speed.  Now they pull out of the dive (not crashing into the ground, like I normally do  ).  The 500 pound airplane will have much more energy, because of its greater weight.  Cut the throttles, and go into a climb, and the 500 pound airplane will go much higher, because it's greater weight gives it more energy to use in the fight against gravity. 

  Now, in level flight, or even a turn fight, the lighter plane can have the advantage because it's engine can push it faster.

[BaldEagl]

  Nope, they would hit at different times, but not because of their mass, because of the difference in air resistance.  Acceleration due to gravity is 32ft per second per second, regardless of mass.  But greater air resistance will cause one to fall slower.

Fixed

[FLOOB]

The force of Gravity is a constant multiplied by the mass of an object. The greater the mass the more force.

The greater the mass the more inertial force. The feather fell as fast as the hammer because gravity exerted equal force on the hammer and the feather, thus the force of gravity can not be increased or decreased by an objects mass. That means the force of gravity is not proportional to the objects mass.

Mongoose is right.

[FLS]

The greater the mass the more inertial force. The feather fell as fast as the hammer because gravity exerted equal force on the hammer and the feather, thus the force of gravity can not be increased or decreased by an objects mass. That means the force of gravity is not proportional to the objects mass.

Mongoose is right.

The force per unit of mass is constant. As Badboy put it, f = ma. For every unit of mass the force is increased. The force is in proportion to the mass.

[LCADolby]

So this is a thread about the best energy fighters...

I'd consider these being the top 5

109K4
F4U4
190D
P51
P47M

[FLOOB]

The force per unit of mass is constant. As Badboy put it, f = ma. For every unit of mass the force is increased. The force is in proportion to the mass.

As you see in F=ma, gravity isn't part of the equation. F=ma, even in a zero gravity enviornment. The force you speak of being calculated with that formula is inertia. Galileo was right.