American bullshit ?

A recent tv documentary featured an interview with a senior NCO of the USS Ronald Reagan, a nuclear powered carrier. This person stated that the catapults of this ship were capable of launching a Volkswagen 12 miles. Surely this is a load of bollocks for several reasons ? :-

1. Anything without power of it's own launched off the deck of a carrier by catapult would have a very flat trajectory. This being the case surely it would be unable to maintain "flight" for this distance and would drop into the sea long before 12 miles had been covered !

2. Also, any Volkswagen ( or indeed any other vehicle ! ) would be broken into pieces by any imparted velocity capable of projecting it this sort of distance ?

What a load of bollo !
BG

 

Re: American bull**** ?

There were no nuclear aircraft carriers in WWII.

 

The Volkswagon's [Beetle] is still around.

Of course he may have been using the 'bug' as an example of the weight they can throw around. (My theory anyways)

 

The catapults on a modern CVN will launch a small car with impunity.

A couple of hundred yards, maybe, but not 12 miles. IIRC, 12 miles was the range of the main batteries on our battleships. Those rounds weighed damned near as much as a VW, so maybe the Chief was confused?

 

The 14in guns of the New York class fired a 1500-lb shell to a range of almost exactly 12 nautical miles.

 

Maybe he meant 'are powerful enough to throw it 12 miles should that be practically possible' - but then 12 miles is an awfully long way - how powerful are those catapults anyway? :-?

 

Not as powerful as a good hyperbole.

 

I calculated that in order to shoot an object 12 miles (statute) away, with launch angle of 45 degrees and without any friction, we need launch velocity of about 435 m/s which is over 1400 fps. Ofcourse if we take account all frictions and launch angle of 0 degrees, we arrive to very, very much higher launch velocity.

 

The American 6in/47 gun aboard the Brooklyn class fired to slightly beyond 12 miles at an elevation of 45 degrees. Muzzle velocity was 2500fps.

 

Flat trajectory

I have not problem with any big gunned warship being able to fire shells out to 12 miles or more when they fire at a pretty steep angle, but nothing fired on a flat trajectory is going to cover that that range. I guess that the Non-com who made the statement about firing a VW that distance was either delivering a good line shoot or was a victim of advanced self delusion !

Thanks for the replies, amigos !
BG

 

yeah ive heard that before to, but i heard last night on David lettermen when the black guy from the all state commercials was talking his dives and he dived on a Japaneses battleship and talked about those guns being able to fire a Volkswagens some thing like 13 miles or something.

 

I have all idea that the reference is to the energy expended by a cat shot. Not that it is practical to fire a small automobile 12 miles in actuality. I wouldn't be surprised if the kinetic energy used to accelerate a 50,000 lb aircraft from zero to 150 mph in a few hundred feet would be sufficient theoretically to accelerate a 1500 lb auto to the required velocity.

ps I fail to see why the nationality of the people involved has anything whatsoever to do with this question?

 

It really has nothing to do with the maximum energy a catapult can generate...the max speed of a steam catapult doesn't exceed 180kts...

 

Nothing to do with the kinetic energy? Hmm...I'm not well versed in physics but it seems to me that given the proper leverage, kinetic energy can be converted to velocity. The heavy weight on a medieval type catapult(edit- should have said trebuchet) does not drop at great velocity however the potential energy of the elevated weight is converted to kinetic energy by the long lever of the catapult arm which results in imparting high velocity to the missile.
In any case my point was that I doubt that anyone who had served on a carrier truly believes that a catapult can throw a car 12 miles. The reason I say this is because it has been done before, i.e throwing automobiles using the steam catapult. They have, on occasion,done so as a sort of test of the catapult (as well as entertainment for the crew). Anyone who has seen that could plainly see that the car travels at most a few hundred yards before plunging into the sea.
I will try and find some photos of this being done. It has been shown on television before also.

This photo comes from a site about hoaxes as some people think that it was a hoax. I can't verify the authenticity of this particular photo but there is no doubt that it has been done before. There are comments on this site by ex Navy types who give more details.

 

They might have achieved that distance had they substituted a Triumph TR-7 for the Volkswagon Beetle.


Tim

 

That would be a trebuchet, I believe.

 

Thanks for the correction, a trebuchet is indeed what I was referring to.

The photo link is apparently dead. I will try to find another.

 

I'm not particularly well versed in physics either, but I believe the medieval Trebuchets use the different principles to achieve the range and velocity of their projectiles. A heavy weight on the short side of one arm will move a lighter weight much faster on the opposite, longer side and that will launch it.

The problem launching a car that far with a steam catapult is that regardless of how much force is behind the catapult it will only move the car at a maximum of 180 kts, and this clearly is not going to be enough to get the car that distance on such a flat trajectory, I doubt it'd be possible on any trajectory to be honest. The kinetic energy IIRC is related to the mass of the car and the velocity of the car.

The energy of the catapult is converted into velocity, but only up to 180 kts, it doesn't matter how much extra force is exerted (Which in any case will already far exceed that required to accelerate something as light as a car to that speed in that amount of time), the thing can only go up to that speed so the car will only go up to that speed.

In any case:

Agreed entirely.

 

Afraid I didn't make myself clear. My point was not that it was practical to actually use a steam catapult to throw a car 12 miles but that the catapult expends enough energy with each shot to throw a car 12 miles.
Stated another way. If a single cat shot has the potential energy to throw a 50k lb weight at 180 kts then it most likely has the potential energy to throw a 1.5k weight at a much higher velocity(were it configured in a way to efficiently impart that energy to the car..which of course it is not as it is presently configured). Your point is well taken regarding the inability to convert that excess energy into velocity(as the catapult is presently configured). It isn't practical.
The kinetic energy that results from the velocity and mass of the projectile is derived from the potential energy that was converted into kinetic energy when it fired the projectile.
The potential energy in a taut bowstring converts to kinetic energy when the arrow is loosed.

 

Ah I see, sorry.