Acceleration in a blowpipe

I am interested in acceleration, and was wondering how to get maximum acceleration at the end of for example a blowpipe, or a gun?

Answer:

You probably know that acceleration (a) is given by the formula a = F/m where F is the force applied and m the mass of the projectile.

So lets assume that we have a projectile of a given mass (say 1 kg). This means that the acceleration (a) = F. (with the correct units of course) The bigger the force the bigger the acceleration. So for our blowpipe or gun we need a really big force pushing the projectile up the barrel. I am not an expert on ballistics but I guess that means a high explosive charge in the case of a gun and a lot of puff in the case of the blowpipe. The 'puff' should be delivered in a short sharp burst.

If you are just interested in the acceleration of the projectile and not its final velocity then the length of the barrel is not important. However if you want your projectile to reach a really high speed as it leaves the barrel then you need a long barrel. Pushing on the projectile for longer (with the same force) will make it reach a higher speed. This is why a javelin thrower will bring their arm back behind their body at the start of the throw so that they pull on the javelin for the maximum amount of time during the throw.

Here is an extract from the acceleration section of the Advanced level part of the site:
Our bodies experience a whole range of accelerations during our lives. A family car may reach 3 ms^-2 during acceleration, the acceleration of objects falling freely in the Earth's gravitational field is about 9.8 ms^-2 and pilots of military jets may reach up to 50 ms^-2. The centripetal acceleration that we experience at latitude 51^oN due to the rotation of the Earth is only 0.007 ms^{- 2}.

However some animals can experience large accelerations, a perch may reach 33 ms^-2, a bush baby 180 ms^-2, a woodpecker 1000 ms^-2 when pecking and when a flea jumps it may achieve 1400 ms^-2!

The thing about acceleration is that it is a change of speed during a given time and so to speak of the acceleration 'at' the end of the barrel or blowpipe is not really right. The acceleration 'up' the barrel or blowpipe is a better way of looking at it. It is the change in speed as the projectile moves up the tube.