Lol... the "beep beep beep" of your equipment is exactly the same as the one on my kitchen timer, so during the video I was standing up because I thought my Lasagne was done 😄
Does this depend on the ambient air temperature? In a nice Aussie daytime temperature of (looked like) 25deg, your lowest temp recorded was 5-6deg - so if your launch day air temp is below say 19-20deg, you would be in trouble?
Yes, ambient temperature does have some impact on that. So will the increased air flow that we hope to achieve. We may give it another test when its cooler to see what happens.
You can speed up your fill time and get higher pressures at the end by cascade filling from your bank. It's how we fill scuba tanks when blending. Rather than turning on both bank cylinders from the beginning, only turn on one fill until the pressure equalises, which will happen at a lower pressure as your volume difference is greater, then turn it off and turn the other on. Rather than use HP hoses, you can get a decanting whip, which is made for this purpose and has a much higher flow rate, HP hoses are designed to have a low flow rate as all they do is pass pressure to a gauge. Its also worth noting if you drain tanks to the atmosphere like you did at the start, put them upside down. That way, any condensation that forms on the valve and melts can't run into your cylinder and cause corrosion.
All good points. One problem with opening the tanks one at a time is that we can't do that remotely. The tanks are located at the launcher with the control box which is remotely controlled from 50m away by a laptop. You don't want to be anywhere near the pressurised rocket. That's why we have it set up this way. We will replace the HP hose spool swivel with a Teflon washer to seal it like we have done in other parts of the launcher. The washer has a hole of around 3mm so should give more than enough air. We had already drilled out the micro holes on the other end of the HP hoses. Regarding the emptying the tanks, we did leave a couple of bar in there for exactly that reason so moisture wouldn't enter.
A few years ago I was working with supercritical CO2. The inner diameter of the steel tubes carrying the gas was a fraction of a mm and we did free expansion of CO2 with a pressure up to 1000bar. To prevent the tubes from freezing we had hoses with warm water coiled around the steel tubes. A thermostat controlled the temperature of the water. Alternatively you could also use a foam jacket around the tubing if icing becomes a problem.
Hi Dan, Interesting info about the CO2, 1000bar is quite a bit of pressure :) I am hoping that with the normal ambient temperatures we should be ok, perhaps we just leave the whole thing exposed to the sun to keep it warm.
Yes they use a compressor and fill with atmospheric air. Often they pre-fill large storage tanks and then when you need a fill they transfer from those which is much faster and do it in about a minute or two.
You could use (dry/pure) nitrogen. They use it on aircraft tires so that ice does not form in a tire to make it unbalanced. Yes it will still absorb heat when it expands, but there may be less moisture in it, at least. Cool channel, thanks.
With an Arduino you could add a temp sensor to the valve. Then have it shut off the valve at like 10C and open back up at 15C. This way you might be covered in all weather conditions. If for example it's a bit cold out. It would also automatically give you your pulses and open fully at the end.
In theory, you should have an emergency burst disk of pop-off valve some place [inside a special safety cage/box] so that if the lines will not close, there is a safety relief in the system.
Yes, in general the air is dry when they fill the tanks at the dive shop, so I am not too concerned on internally freezing the valve, though there may be some moisture in the hoses, though that would be minimal. The big problem is atmospheric moisture getting frozen around the stem outside of the seal which is quite deep in the valve.
@@AirCommandRockets Some people use preheater buffers, but since you were worried about heat building up in the actual rocket, that would clearly not work in your situation. It is good to know that the final thermal mass load was high enough at those filling speeds as to not cause an issue. One can always box up the control module with some calcium chloride such as to keep it dry internally, they sell 'damp-rid' in small, disposable containers, just reduce the excess free flow of external air into the module, and only open the damp-rid lid just before filling the tank, then closing it up between uses. I buy that stuff in 6 Kilo containers to control moisture here in the states.
Another thing that would be interesting to see is the temperature drop in the rocket tank during launch. Its gonna be difficult getting a thermometer in there though,
We do have one test pressure chamber where we have glued into it a thermo couple so we can measure the internal temp. I think we have a video of that somewhere but only as a static test rather than in flight, but can't remember which one it was.
Lol... the "beep beep beep" of your equipment is exactly the same as the one on my kitchen timer, so during the video I was standing up because I thought my Lasagne was done 😄
mmmmm.... Lasagna .... might have that for lunch today :)
Always nice to hear from you guys
Thanks, it's been way too long since we posted a video.
Great work as always team. “See the temperature of Grandpa’s forehead”, cheeky so-in-so….😊
Thanks :)
Jó látni hogy mindig együtt alkottok 🎉😊
I remember doing water rocket as a kid great times.. now my son is old enough to do it with him. Thanks for the content
Thanks for following along.
Does this depend on the ambient air temperature? In a nice Aussie daytime temperature of (looked like) 25deg, your lowest temp recorded was 5-6deg - so if your launch day air temp is below say 19-20deg, you would be in trouble?
Yes, ambient temperature does have some impact on that. So will the increased air flow that we hope to achieve. We may give it another test when its cooler to see what happens.
You can speed up your fill time and get higher pressures at the end by cascade filling from your bank. It's how we fill scuba tanks when blending. Rather than turning on both bank cylinders from the beginning, only turn on one fill until the pressure equalises, which will happen at a lower pressure as your volume difference is greater, then turn it off and turn the other on.
Rather than use HP hoses, you can get a decanting whip, which is made for this purpose and has a much higher flow rate, HP hoses are designed to have a low flow rate as all they do is pass pressure to a gauge.
Its also worth noting if you drain tanks to the atmosphere like you did at the start, put them upside down. That way, any condensation that forms on the valve and melts can't run into your cylinder and cause corrosion.
All good points. One problem with opening the tanks one at a time is that we can't do that remotely. The tanks are located at the launcher with the control box which is remotely controlled from 50m away by a laptop. You don't want to be anywhere near the pressurised rocket. That's why we have it set up this way. We will replace the HP hose spool swivel with a Teflon washer to seal it like we have done in other parts of the launcher. The washer has a hole of around 3mm so should give more than enough air. We had already drilled out the micro holes on the other end of the HP hoses. Regarding the emptying the tanks, we did leave a couple of bar in there for exactly that reason so moisture wouldn't enter.
A few years ago I was working with supercritical CO2. The inner diameter of the steel tubes carrying the gas was a fraction of a mm and we did free expansion of CO2 with a pressure up to 1000bar. To prevent the tubes from freezing we had hoses with warm water coiled around the steel tubes. A thermostat controlled the temperature of the water.
Alternatively you could also use a foam jacket around the tubing if icing becomes a problem.
Hi Dan, Interesting info about the CO2, 1000bar is quite a bit of pressure :) I am hoping that with the normal ambient temperatures we should be ok, perhaps we just leave the whole thing exposed to the sun to keep it warm.
Awesome content as always. Does the dive shop use just a compressor to fill the tanks so it's just atmospheric air?
Yes they use a compressor and fill with atmospheric air. Often they pre-fill large storage tanks and then when you need a fill they transfer from those which is much faster and do it in about a minute or two.
You could use (dry/pure) nitrogen. They use it on aircraft tires so that ice does not form in a tire to make it unbalanced. Yes it will still absorb heat when it expands, but there may be less moisture in it, at least.
Cool channel, thanks.
Good to see you guys uploading again. Do you think the launch will me this year?
We are hoping to try during the club's high power launch in August. Lot's of work to do before then. :)
With an Arduino you could add a temp sensor to the valve. Then have it shut off the valve at like 10C and open back up at 15C. This way you might be covered in all weather conditions. If for example it's a bit cold out. It would also automatically give you your pulses and open fully at the end.
We already have a Raspberry Pi there sending data back to the remote laptop. Probably wouldn't be difficult to add a temp sensor.
@@AirCommandRockets yeah, it would be pretty easy.
In theory, you should have an emergency burst disk of pop-off valve some place [inside a special safety cage/box] so that if the lines will not close, there is a safety relief in the system.
We have made one of these that is adjustable. It's detailed here: ua-cam.com/video/yynT8bLQOTE/v-deo.htmlsi=Q_0oXJWzAlt1kUyu&t=166
As long as the gas inside the tank is dry, ice can not become a problem internally.
Yes, in general the air is dry when they fill the tanks at the dive shop, so I am not too concerned on internally freezing the valve, though there may be some moisture in the hoses, though that would be minimal. The big problem is atmospheric moisture getting frozen around the stem outside of the seal which is quite deep in the valve.
@@AirCommandRockets Some people use preheater buffers, but since you were worried about heat building up in the actual rocket, that would clearly not work in your situation.
It is good to know that the final thermal mass load was high enough at those filling speeds as to not cause an issue.
One can always box up the control module with some calcium chloride such as to keep it dry internally, they sell 'damp-rid' in small, disposable containers, just reduce the excess free flow of external air into the module, and only open the damp-rid lid just before filling the tank, then closing it up between uses.
I buy that stuff in 6 Kilo containers to control moisture here in the states.
happy to hear from you guys, btw, is there an issue on your website? I get a 404 error when I try to go on it
Should be working fine. Here is the link: www.aircommandrockets.com/
Another thing that would be interesting to see is the temperature drop in the rocket tank during launch. Its gonna be difficult getting a thermometer in there though,
We do have one test pressure chamber where we have glued into it a thermo couple so we can measure the internal temp. I think we have a video of that somewhere but only as a static test rather than in flight, but can't remember which one it was.
A FLIR camera view would be interesting. And isn't invasive.
@@simonabunkerI actually looked at getting one of these, but they are a little on the expensive side. Even to rent they can be quite pricey.