Thanks for the link and image, Mint. That’s the sort of thing I’m chasing.
Ambient temp is weather dependent, generally 10-25C. Static body of water. If it takes 12 hours to equalise the temp, that’s not a big issue.
Acceptable tolerance is quite large, likely to be +/- a degree (C). The...
Hi, is there a COTS item to heat/cool/maintain the temperature a body of water?
The water volume is approx 3-400 litres, and temps held within approx 10-30 degrees C.
Can anyone think of something which might suit the need?
Thanks.
Fox, the weight of the item holds it in place.
Inch, it's for testing/safety purposes.
3D Dave - that's a good idea. Sometimes we use compressed air as an actuator, but this is even simpler.
Hydtools - thanks. That's the sort of thing we're after (albeit with a very long cable).
Mint - I...
Good idea, Brian. That would simplify the release. I presume you mean to use the extension spring at the bottom of the picture with a release pin through one end?
IRstuff:
> what is the purpose of the spring?
To ‘open’ the device quickly once the hold-shut mechanism is released.
> what is...
I have a problem I'm struggling to solve.
Think of hand-dropping a mortar round down a tube then moving away. I want to be able to do that, but remotely and without electronics/solenoids etc. An video example of what I'm trying to achieve is here: https://www.youtube.com/watch?v=QTbuGpCBUQE...
Thanks - a great idea.
The only downside I see is that it's another area where the system can 'leak', but it's likely to be a small surface and simple to seal.
Apologies for the delay.
I feel I've made several mistakes here:
1. Posed an unclear question (noted, will try and not let it happen again). This likely mislead bimr - apologies.
2. Made a silly assumption at the start, forgetting about P above the surface of the water.
For context, work is...
Where I (think) I went astray was only including gauge pressure. Ie, pressure (absolute) = gauge (internal P) + Absolute (or, pressure at the top of the fluid).
But, now I read bimr’s post I’m again uncertain!
Good point… I feel daft now.
Then, if I wanted to simulate, for example, 1m of depth I’d just increase the pressure by 1 ATM/14.7psi?
That sound right?
Please help settle a discussion…
As per the picture, can you increase the pressure in the water by increasing the pressure in the air above? It’s a sealed container.
If yes/no, why?
I thought you couldn’t, due to P equaling rho x g x h. But someone else reckons you can, and I’m second guessing...
Thanks, hydtools!
Just to 'close this off', I ended up realising that the momentum method only works for linear acceleration. As a round doesn't act in this manner, I used the data given to make a 'best estimate' as I don't have access to velocity profiles in the barrel. At max acceleration, it...
Rb1967, I’m not sure where I said I was overly interested in the time from round ignition to leaving the barrel. That duration is a known.
That said, I have since realised that using the momentum method I ignore the rifling friction force, which I’ve read is ~10%. Also the pressure of the gas...
Thanks, Irstuff.
We can gather the max chamber pressure and sometimes pressure near the end of the barrel, but don’t know anything about what happens in between (ie gradient of pressure or acceleration between the points). We also get exit velocity as close to leaving the barrel as possible...
Thanks for the all the responses.
For context, I will have access to timings from firing to round exiting the barrel.
Regarding the barrel length, I don’t understand the relevance. As in, my limited understanding is that generally a longer barrel will have higher round exit velocities, but...
Thanks, 3D Dave.
I've tried a few calculators and they give me the Joules, but I can't recall how to turn that into a force.
Are you able to confirm if the momentum methodology makes sense?
Thanks.
