Boosting Gun Efficiency: Exploring High-Velocity Bullets

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Discussion Overview

The discussion revolves around the concept of enhancing gun efficiency through the use of high-velocity bullets and the potential benefits of detonating gunpowder in a chamber with compressed air. Participants explore the implications of pressure ratios on energy extraction and bullet velocity, touching on ballistics and theoretical efficiencies.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant proposes that detonating gunpowder in a chamber with compressed air could increase energy extraction efficiency due to higher pressure ratios, potentially leading to higher bullet velocities.
  • Another participant shares a link related to ballistics, indicating a lack of expertise but encouraging further exploration of the topic.
  • It is noted that the pressure generated by burning propellant is significantly higher than what could be achieved with a pump, suggesting limited benefits from additional energy input.
  • A participant estimates that a detonation pressure ratio of 18:1 could yield a theoretical efficiency of 68%, while compressing air to a 4:1 ratio might increase efficiency to 81%, although this would require thicker casings and a new method for powder injection.
  • Questions arise regarding the origin of the 18:1 pressure ratio, with one participant admitting it was an estimate and another providing a figure of about 50,000 atmospheres for the pressure generated in a gun.
  • One participant suggests a simpler approach to increasing efficiency by using more gunpowder and a longer barrel.

Areas of Agreement / Disagreement

Participants express differing views on the feasibility and implications of using compressed air in conjunction with gunpowder. There is no consensus on the effectiveness of the proposed methods or the accuracy of the pressure ratios discussed.

Contextual Notes

Participants acknowledge uncertainties regarding the actual compression ratios generated in firearms and the practical challenges of implementing proposed changes to gun design.

sid_galt
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If the gunpowder in a gun is detonated in a chamber consisting of compressed air such that the top of the chamber is formed by the bullet, wouldn't the efficiency of energy extraction from the gunpowder increase as the pressure ratio will be much higher? Would such a bullet be able to achieve much higher velocities?
 
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Hi sidgalt!

To say the truth I have no idea about ballistics. Anyway, I thought you will find interesting this link:

http://www.aa.washington.edu/AERP/ramac/

It's great. Try to look into it and post a comment here if you want.
 
Last edited by a moderator:
The pressure generated by the burning propellant is orders of magnitude higher than you could provide with any reasonably-sized pump, so it really would help much to add that tiny bit of energy.
 
Clausius2 said:
Hi sidgalt!

To say the truth I have no idea about ballistics. Anyway, I thought you will find interesting this link:

http://www.aa.washington.edu/AERP/ramac/

It's great. Try to look into it and post a comment here if you want.

Thanks for the link Clausius2. It's fantastic. I had no idea they were using ramjets to power projectiles.

russ_watters said:
The pressure generated by the burning propellant is orders of magnitude higher than you could provide with any reasonably-sized pump, so it really would help much to add that tiny bit of energy.

Assuming detonation gives a pressure ratio of 18:1, the theoretical efficiency is 68%. If we compress the air beforehand to a pressure of say 4:1, then the theoretical efficiency rises to 81%, a 13% difference. I would say it's quite a lot. Of course the casing would also have to be 4 times thicker and a method of injecting gunpowder pellets will have to be arranged.
 
Last edited by a moderator:
It was off the head. I did a google search but I coudln't find the compression ratio generated in a gun
 
sid_galt said:
It was off the head. I did a google search but I coudln't find the compression ratio generated in a gun

It's about 50,000 atmospheres. Good luck trying to compete with that
using a pump.
 
Or you could do it the simpler way... more powder and a longer barrel...

Cheers...
 

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