This week we build and test fly a prototype parachute deployment mechanism for the booster. We also look at some data about how fast the parachute opens and what sort of forces it puts on the rocket.
I love how simple this design is, very well done! Also thank you very much for buying a Rockit flight computer and helping me develop the firmware. Looking forward to watching the next episode of the Horizon series :)
Hello George Another very nice (and very clean...) realization. I admire the work on the fiberglass and the carbon... The folding of the parachute is impeccable. My method is different, but the main thing is that it works. I also place a piece of tape on the retaining cord. And I see that you are now attaching the parachute to the center of gravity of the rocket. Thanks again for your great videos !
Merci Francois, Yup we want to bring the rocket down sideways so that it increases drag and it also means that the nozzles don't hit the dirt first. Bringing it down sideways means that we have to run the shock cord down the side of the rocket. I am not too happy how it just hangs there, I think we may have more tape for the final rocket.
@@AirCommandRockets You may can use peel ply clothes (1 or 2 layers) for hinge. Both ends must glue/epoxy between the airframe and door layers and only a very thin strip (0,5-1mm) left uncoated.
@@andrasmeszaros8985 One problem for peel ply is that it is designed to separate from epoxy. But this is something we plan to investigate is making a hinge with cloth that won't separate easily from epoxy. We will use a gel epoxy that should not wick into the flexible part of the hinge. Edit: I have just had a look and people do make hinges from peel ply. I will have a look at this, I think I have a way of perhaps using it where it should be a little more secure. So thank you for the suggestion.
Thank you for your promise, I will appreciate your word. First Idea: by conducting simple calculations, we find that changing the diameter of the thrust nozzle with the change in the weight of the missile and the change in gas pressure leads to an increase in efficiency. For example, we can use a rubber nozzle, with high pressure at the beginning, its diameter is greatest, the flow is high, the force is great, and it gradually decreases. Until the water in the rocket runs out. We can use a more complex nozzle similar to the F-22 Raptor's thrust nozzle (square hole with two spring-bound wings).
In terms of a variable nozzle. We have already done those tests back in 2008 www.aircommandrockets.com/day65.htm#vid_variableNozzle and here are some captures from the video: www.aircommandrockets.com/images/day65/VariableNozzle.jpg
Back when I built and flew R/C gliders I had spoilers on them that were designed to use tape for the hinge. I did not like this so I designed a hinge that I believe will work for you deployment door. Use a thin piece of piano wire as the hinge pin with either 3D printed hinges or like I did, small glue in nylon hinges. The piano wire was also used as a torsion spring that held my spoilers close tight and flush with the wing but you could reverse it to hold the door open. Basically the legs on each end of the wire hinge pin are twisted 180 deg out of plane with each other and used to torsion the door open. Wire diameter will vary the torsional force. The tape does not look like it would stand up long with the aerodynamic forces trying to peal it along its length.
Nice! I like the concept of the torsional piano wire acting as both a hinge and the spring mechanism. That's nice, clean, compact and shouldn't be affected by the blast of water coming from the second stage. Thanks for the suggestion. :)
Fourth idea: The design of the cannon barrels inspired me with this new idea: that the missile should consist of two or more bottles, a small bottle inside the large one. This will inform us that the small bottle is surrounded by high pressure, and therefore we can charge it with more pressure than usual, and add that the small flask naturally bears more pressure. This idea is complex to manufacture. But theoretical calculations will increase the energy for weight. Imagine, for example, if there were four bottles inside each other.
Third Idea: By conducting theoretical calculations of the shot stored in the missile, the energy released from it, and the maximum height, we find that theoretically we can achieve a greater height if we extract the energy stored in it in a way other than direct jetting, i. It is powered by the turbo engine. But our calculations indicate that at first the thrust is not sufficient to lift the rocket with its payload, so the new rocket could be of two stages as in space rockets, the first stage being two medium side rockets with jet-propulsion for lifting, and the main rocket with turbo-propulsion. The difficulty here lies in placing a small water turbine to extract the energy of pressurized water and then the remaining compressed air. the Rocket can look like as Virginia submarine.
Nice and stable behavior when hanging under the parachute. I think I will modify my water rocket to this two point shock cord mounting. I'm not sure, if landing on fin or on nose cone is better.
You can adjust the angle so that either nose or fins hit first. Note that the fins will generate some lift on the way down changing that angle somewhat. But falling sideways like this should provide a stable platform for a camera looking down.
Second Idea: It is well known that the small bottle can withstand greater gas pressure than the large bottle before it collapses. So one of the important improvements I made is the following: use a large, long main bottle that contains the most amount of water and the least amount of compressed air, and use two, three or four bottles that contain the most amount of compressed air and the least amount of water connected to the main body of the rocket with a valve Set to a certain pressure is the collapse pressure of the large main flask. And by doing the calculations, we find that we can maintain the air pressure above the water and get a constant push for a longer period of a larger amount of water.
Yes the water chamber doesn't need to be as strong as the chamber with the gas, if you can make sure that the water chamber doesn't overpressurise as you release the gas into it. You will add extra weight though for your valve mechanism. I know this idea has already been attempted before by others, sorry I don't have a reference.
Fifth: We can use this idea for simple school rockets, which is to strengthen the flask by creating circular annular fusion with a thermal resistance wire, so that the shape of the flask from the inside becomes like an airplane or a submarine, rings of plastic.
Here is more info on the Servo Timer II. www.aircommandrockets.com/servo_timer_V2_0.htm Unfortunately these are no longer for sale, but we do provide all the details, firmware and PCB designs if people want to make them themselves.
You may have mentioned in a previous video, and this spring loaded system looks like it works pretty reliably, but why not go for a traditional black powder charge separation mechanism?
This is a good question. There are a number of reasons why we prefer a servo based deployment mechanism. 1. We don't need a pyro license to buy and store black powder. 2. There are no consumables so we can test the mechanism dozens of times. There is no additional cost for black powder or e-matches every time we want to do a test. 3. No residue to clean up. 4. No need to protect chute from hot gases 5. Energetic charges aren't a great idea next to pressurised vessels.
The Nova deployment style mechanism can't be used in this case because the parachute is just too big and the door on the nosecone would be directly impacted by the blast of water coming from the second stage which would most likely break it. That jet of water coming from the second stage is strong enough to easily bend 2mm aluminium plate. (this is from experience)
Excelente George!!! , como siempre. Que buen trabajo se logra con una impresora 3 D. Una pregunta, cuantas botellas de 2 litros forman ese cohete? Saludos
Can the retention rubber band be swapped with something that doesn't stretch? I'm afraid the slipstream could force the parachute door to open with that rubber band holding it closed.
what i like to do in ksp is sequentially open my parachutes to spread out the g load, i dont know how viable that is in reality / leads to the rocket shaking too much. the way your chutes are spread out i can imagine helping it guarantee that the 2 chutes dont entangle each other.
The parachutes will be deployed by completely independent systems so it is unlikely they will both deploy at the same time. In previous flights we've found that once one parachute opens, and the rocket slows down, the second parachute takes a lot longer to open due to the lower air speed. Here is an example of what I mean: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-0qzOzjRJpaU.html
hey George! I have a questions. I'm planning on making a carbon fibre water rocket and was wondering if you know how much pressure just carbon fibre could hold. I've also seen that you 3d print the molds for your end caps and was wondering if I could potentially use normal bottles with their ends cut off. then keep those inside the pressure chamber but add carbon fibre on the outside of the bottles to make sure they can hold enough pressure. Thanks!
Hi, sounds like a fun project. How much pressure carbon fiber will hold depends on a couple of factors: The wall thickness and fiber orientation in the walls of the pressure chamber. The wall thickness depends on how many layers you have or what the fiber count is in the cloth. There are different weight cloths. You should be able to use bottles on the inside. If you are going to use bottles, I would recommend splicing the bottles first to make a waterproof pressure chamber internal bladder, that way you know it's sealed and then reinforce the whole thing with carbon fiber. This way if you end up with small holes in the carbon fiber it won't leak. Also consider using just fiberglass as it is much cheaper and it's strength is perhaps only 30% weaker than CF. Regarding fiber orientation, there is an ideal winding angle of 55% for cylindrical pressure vessels.
That looks promising, although I am guessing that you will need a much stronger latch for the door on the actual booster (due to the drag from such a high-speed launch). Is there any progress on repairing the leaking nozzles on the booster segments?
Yes, the latch mechanism will be very different on the actual flight hardware. This was purely a test of getting a large parachute out of the airframe. The door will also have a much more secure hinge. We are in the process of attempting to repair the leaks over the Christmas break.
You will find most information on water rockets on-line. There is lots of information on our website with articles, tutorials, flight reports and more: www.aircommandrockets.com/
I'm interested in building a water rocket of my own and was wondering if in your experience plastic quick connects for garden hoses are capable of handling at least 100 psi or if brass ones are needed.
I am an aeronautical engineer and a marine engineer and I have an innovation that will double the range of a water missile, but this invention is a total change in the design of the body, do you have an interest?
@@AirCommandRockets I may get a patent for this development, so I want to ask you, will you give me a promise man to man, before God, if I get a patent or any profits from it, that my name will be with you and I will take half of winns. Someone may say that I am stupid to give my thoughts to others and how to trust someone I do not know, but I believe in God, if someone takes away my right in this worldly life, I will not forgive him and God will judge him on the Day of Resurrection. So will you promise me that my name will be next to yours, and that I will get half of the profits, if any?
how about steam rockets, or hot stone + water = steam, or maybe termite + water = steam rocket, ultra fast pressure, if proper ratios, termite itself is not a rocket fuel, but with water steam tube it is, a water propellant
Steam rockets have certainly been done, but that is a different class of rocket. Steam rockets use a phase change (liquid to gas) to generate thrust, whereas, regular water rockets don't. Here is a good example of a steam rocket: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-zLjaBDZ2J2o.html
Yup all good. It's been a while since our last video. :) We have been busy with rocket projects, we have a backlog of about 5 videos that we need to finish editing. Just getting ready with a new side project for a launch event next week. After that we should be able to catch up on the backlog.
