I love your construction investigations and revisions. It's been quite enjoyable watching ACR progress to this point. Looking forward to the maiden flight!
I can’t believe I found your channel again! I remember 12 or 13 years ago I would visit your website daily because I was a 12 year old who wanted to have the wildest hobby. So many years go by and you’re still doing what you love. I really admire your work back then and now I feel like your projects should be the gold standard for water rocket engineering. Stay safe and have fun, George.
Thanks, it has taken a few more iterations than we had originally expected, but we're happy with the current process.
3 года назад
Last weekend, I made a pressure test on a 125mm (diam.) pressure chamber with 3 layers of 200g/m² carbon cloth. For security and to avoid scaring neighbours if it explodes, made it in my garden in a cavity, 25cm under the earth. I reached 53.5BAR for 10 minutes without any leak. But after 10min the co2 slowly dissolved in the water and the pressure decreased. So I made sparkling water. ^^
That's a good result! Just curious, how fast was the CO2 absorbed? In terms of over that 10 minutes, how much did the pressure drop?
3 года назад
@@AirCommandRockets The camera with which I filmed the manometer stopped after a few minutes. So I have the data only for the beginning. It toked 390s to drop from 53.5BAR to 49.5BAR. So it's approximately -0.6BAR/min.
Yup, things that seem should work, end up not working when under load. There is still a long way to go with these pressure chambers, we still don't know how it will behave when the compressed air heats the epoxy from the inside. We also don't know what the upper burst pressure is yet.
Hi George, love how meticulously you build your rockets. I was wondering what would happen if you disolve a gas in the water like CO2. Keep up the good work. Greetings from the Netherlands.
Thanks Adriano, that is a good question, we've often wondered this ourselves. A few years ago we did a test on the test stand where we used a carbonated drink as the liquid, but didn't see much of a difference in performance. It may be different though if the pressurant gas was also CO2. Something definitely worth investigating.
The lizard was just inspecting the safety precautions :) In regards to use of fibreglass and carbon fibre around the nozzle. Fibreglass has high strength but relatively low young module, it will stretch 6 times that of a carbon fibre before breaking. Carbon fibre - the opposite, very high rigidity, so in principle all the fibreglass should go on the inside and ensure the seal while all the carbon fibre should go on the outside and ensure the mechanical strength. Indeed you do have a lot of fibreglass around the nozzle and it should be fine, but that's just a small consideration I would use. What would be very interesting to see is what happens to the chamber lengthwise while you pressurise it. Does it expands lengthwise proportionally to the circumference expansion or not? The stress that acts diametrical should be D/2*pressure. while the stress in axial direction is D/4 and the chamber that is equally strong in all directions should expand proportionally to those stresses. The ideal case scenario is, obviously, when the chamber is twice as strong in perpendicular direction in comparison with the axial direction.
Interesting missives. I never thought that such rockets could be so powerful. I still have a question how and with what do you pump this airde to such pressures?
Perhaps I missed this, but why construct the pressure chamber from scratch? Versus carbon fiber wrapping several layers inside and outside of a SCH20 OR SCH40 PVC pipe? Or even aluminum? Obviously there would be a weight difference but you'd make up for it with the amount of pressure it could sustain?
Thank you for sharing with us the lessons that you have learned George. How are you planning to fill the pressure chambers with water? I can imagine that filling the booster might be cumbersome.
Use of a reuseable nano gel tape might be more appropriate for creating an inner bead. Application might be made to each side and then pulled out of the nozzle during partial cure. Alternatively, a dual silicon balloon mould would assist to negate rotation during mating of the end cap to the body.
Was there a case of leakage due to banding during the test? If there was, I wonder why.
3 года назад
hello my name is Anderson, I participated a couple of years ago in a national competition here in Brazil of a pet bottle rocket by school, I had the best launch but after a year later they broke my record and I wanted your help to break this I remember there, because my state is considered very inferior and I want to show that they are wrong. I count on your answer
Hi Anderson, happy to give some tips but I don't know anything about the competition rules or what performance you are trying to achieve.
3 года назад
@@AirCommandRockets here there are two types of competition, level 3 and easier and only the water scheme in the rocket and to pressurize it is to launch it at an angle of 45°, the record here is 290 meters, whereas level 4 the reaction is different, we mix the vinegar + sodium bocarbonate, and launching the Record here and 363 meters at the same angle, I really wanted your help, can we talk via Whatsapp?
