Throw a Baseball from a moving Car - RC Groups
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Feb 04, 2006, 08:01 AM
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Throw a Baseball from a moving Car


Ok, I think this is starting to click in my head.

From a moving car- you throw the baseball from the said moving car. "The ball will move foreward at its release speed." Now lets say we throw the ball at 50 MPH and we put a jet, rocket or prop on it with the same 50 MPH "Pitch Speed"...... and the cars moving at 50 MPH too. Then what is going to happen?????
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Feb 04, 2006, 08:11 AM
I don't want to "Switch Now"
pmackenzie's Avatar
In all three cases the same thing will occur, the ball will accelerate or decelerate until the thrust and drag match.
In the case of the prop it will decelerate.
Depending on the efflux speed and amount of thrust for the jet or rocket it will accelerate.
( Actually the prop will probably come to an almost complete stop since the ball can't absorb any torque,
so it will end up spinning and the prop will be almost motionless.)
Pat MacKenzie
Feb 04, 2006, 08:15 AM
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vintage1's Avatar
Quote:
Originally Posted by rzzzzz
Ok, I think this is starting to click in my head.

From a moving car- you throw the baseball from the said moving car. "The ball will move foreward at its release speed." Now lets say we throw the ball at 50 MPH and we put a jet, rocket or prop on it with the same 50 MPH "Pitch Speed"...... and the cars moving at 50 MPH too. Then what is going to happen?????
I;d guess you will carsh and get arrested for dangerous driving.
Feb 04, 2006, 09:08 AM
Registered User
Let's say you can throw the ball 50 MPH. You throw the ball from the (50 MPH) moving car, so it starts at a velocity of 100 MPH. Assuming the ball doesn't drop and hit the ground, drag would start slowing it as soon as you release it, until the ball stops.

If the ball had a 50 MPH efflux jet it would still start at 100 MPH on release but slow to a little less than 50 MPH, wherever the thrust of the jet (at that speed) balances the drag of the ball. A propeller with a true, fixed, 50 MPH p-speed would be a big amount of drag at 100 MPH and would slow the ball quickly to a bit less than 50 MPH.

I think what you're trying to get at is that thrust tapers from it's maximum at static (assuming the prop isn't stalled) to zero when the plane is going the pitch speed (never mind unloading and airfoil effects, I'm trying to keep it simple).

Motocalc is a great tool to help figure out some of these things, you can download it and play with it for 30 days free.

Good Luck!


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