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In article <6lTUe.933$LS5.383@newsread3.news.pas.earthlink.net>,
Dave S <Dastaten@earthlink.net> wrote:
> Smitty Two wrote:
>
> > 1. I didn't stipulate a vacuum. My engine and wing do not work very well
> > without air. I said, to simplify calculations, ignore the effects of
> > friction on the projectile. We are flying above the earth.
>
> You said discounting air friction. This is key to the problem. No air
> friction would be the physical equivalent of being in a vacuum.
>
> If there were no air friction, the projectile would continue ahead with
> a forward speed of 1500 mph - its own 500 mph from its spent propellant
> charge, and the 1000 mph imparted to it from the airframe.
>
> Air friction, however, acts on the projectile from the moment it departs
> the muzzle, and acts to slow the projectile in a continuous manner. The
> aircraft continues to maintain its 1000 mph since it has a propulsive
> device that is assumed to continue to operate. Air friction (along with
> gravity) are the forces that conspire to ALLOW the aircraft to overtake
> its projectile and contribute to shooting itself down.
>
> So... are we or are we not including air friction? If we are, I'm not
> going to hazard a guess.. my math gland atrophied long ago after I
> passed calculus. If we are not, then the problem is unsolvable in level
> flight on earth.
>
> Dave
It's a hypothetical question, of course. I think I stated it fairly
clearly. Bill has already answered it correctly, with a second from
Alex. My calculus skills have also eroded over the years, which is one
reason I wanted to discount friction. But, I would be curious to learn what
the real world answer would be, including friction, which of course is
dependent on a whole host of factors. (Of course, by the time the plane
caught up with the bullet in the real world, the friction would likely
have reduced its speed to something *relatively* harmless.)
Now, for some practical math, I hope one of these WW1 guys around here
can help me not shoot the prop off my RV when I put the .50 on the front.
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Re: shooting yourself down - more physics?
