Recent content by RKT

Thanks Stewartcs. In my case, the heat generated by compression is lost before the gas is expanded. The formula takes the heat generated into account. That only means a higher value of sound speed (a0). So if I use the normal value of a0 (a0 at normal temp.) then the formula should give me...

Man ! You have an answer for everything ! So give me your opinion on this : That formula is basically max. wavefront speed for free expansion of an ideal gas, if I am not mistaken. Does it take into account the heat generated by compression ? The term 'a' depends on temperature ... so if I...

Thanks a lot Stewartcs ! I had read abt light gas guns long ago and did'nt bother investigating it again as I remembered that they use hydrogen ... not 'air' that I use ... This is a good find ! So for air, the theoretical max. vel becomes : u = [2 / (gamma - 1)]*a = [2 / (1.4 -...

The site was experiencing problems yesterday ? I could not view it ... Anyway, the fill pressure is 3000 psi. About the speed, I am going to get myself a chronograph, but meanwhile, I'm pretty sure that's its supersonic. I did a little research, you see. It seems supersonic is not a big deal...

BTW, I am not too sure about my initial assumption of a CD nozzle being present inside. As I understand it, such a nozzle produces a low pressure air flow (albeit at very high velocity) Is such a low pressure air column capable of pushing a pellet with such force as to make it exit at these...

Stewartcs, I have'nt setup any apparatus. I am doing a restoration of a pneumatic gun. It operates by discharging HPA through a barrel. The pellet sits between the reservoir valve and the barrel. I was trying to clean the barrel using a soft pellet made of 'felt'. When I fired the cleaning...

Thanks guys ! Guess your answer is that a tube will also limit the velocity to SoS. Yes, I am aware that a CD nozzle can get the flow supersonic. Problem is there is no CD nozzle involved here. I am seeing a case where simple HPA (high pressure air) is going supersonic out of a uniform...

Hiya ! Got a problem about gas flow ... I understand that gas flow speed through an orifice is choked to the local speed of sound once the upstream to downstream pressure ratio crosses a certain number. Any increase of pressure beyond that point does not speed up the flow anymore (though the...

SoS again ... Hiya , The commonly held view is that speed of sound (SoS) in a gas depends on temperature and not pressure. I want to know if this is always true. Consider the following two cases and let me know what you think. In the first case, we have cylinder made of a bad conductor of...

Also, I forgot to mention, since I neglected friction, my numbers should have been somewhat higher than observed values, not 75 % LESSER. It was deep **** earlier, this makes it deeper. Tell you what, why don't we all decide on some input values (reservoir vol, pressure, barrel length, caliber...

Piratephysicist, I didnt go for Vanderwalls corrections as I know that its not going to help a lot. After all, just how much difference is it going to make ? 10 % ? 20 % ? Not more than that I'm sure. I neglected friction as well, however that does not make up for the FACT that the calc...

Piratephysicist, I think you are assuming static pressure all along the barrel. I did a calc. long ago to try and determine muzzle velocity and the tech. I adopted is similar to yours. The results were way off from expected values. I have not retried my calc. but I feel that there's a...

So, let's say that I had a hypothetical airgun that is 100 % efficient in converting the compressed gas energy to useful work. Assume zero losses. From my viewpoint, the only energy that I'll call useful is pellet KE = 0.5 x (pellet mass) x (velocity)^2. Let's also assume that it fires only one...

Stewartcs, Is that number the energy of the gas 'as it is' compressed in the vessel ? If yes, can you pl. tell me how you calculated it ? Shootingstar, I didnt quite understand why you need the barrel vol. I don't need to calculate the energy of the pellet, if that's what you are...

Here's what I am trying to do. I want to know the efficiency of the rig. Thats why I need to know the energy before I open the orifice. You must have heard of pneumatic guns, they are quite a craze these days. We are tryin to estimate the efficiency of a particular model.