# Aircraft Carrier Forces on Impact

1. Sep 11, 2009

### codywookman

I need help finding the forces when an aircraft’s jump cable catches to stop a plane on an aircraft carrier ship. The aircraft is travelling at 110 mph with the front of the plane 3 feet off the deck of the ship. If the assumption is made that the cable stops the aircraft immediately (the cable is not elastic), what would be the estimated impact force on the front end of the aircraft with the following conditions?
-The aircraft is 24 feet long
-1000 lbs located 4 feet above rear axle (pivot point)
-5000 lbs located 5 feet above center of plant (when plane is level)
-1500 lbs located 3 feet above front axle
-Do NOT ignore gravity
-Assume no impact absorbed by the front tire

I think it involves dynamics with momentum, kinetic energy, and maybe more.
L (linear momentum) = mass * velocity
A (angular momentum) = L x r (cross product of linear momentum and vector)

Tried using angular momentum (lb ft2 / sec) but that will not add with gravitational force multiplied by distance and mass (lb ft2 / s2). I'm really stuck here please help get me started!

2. Sep 11, 2009

### Staff: Mentor

The assumption that the cable is not elastic (or on a spool with a brake) is so far from reality that I don't see how it is a useful constraint to the problem. Aside from a momentary impact force of the wheels hitting the carrier (then the continuous force of its weight), the main force felt is the acceleration force of the cable stopping the plane via f=ma.

3. Sep 11, 2009

### Cyrus

I really see no attempt on solving this problem on your end. Please provide more work and thoughts.

4. Sep 12, 2009

### codywookman

I guess I forgot to write in the problem that the only force we are looking for is the vertical force exerted on the front axle of the plane due to it rotating downward so quickly. I misjudged the effect that the cable would contribute so much more to this effect if it were rigid instead of elastic. Any ideas how to solve it without assuming that for the cable?

5. Sep 12, 2009

### Cyrus

Is this a homework problem, or something your just trying to solve. This isn't the kind of problem you use the basic equations you're trying to use. You're not even going to be close.