I build a falcon heavy water rocket, the nose is heavy 250gr, it’s almost 1m long, the balance is great but it feels heavy, I hope it’s powerful enough, if I make it lighter than it isn’t balanced anymore
Yes, I am worried that my eyes could get irritated, and that soreness in the throat could also occur. To my application that I want to work on, is to reinforce plastic so they will be able to withstand more pressure.
@@microbeMan So generally when you are working with fiberglass cloth you are fine in terms of handling it and cutting it. Where you can get irritation is if you are sanding it and the dust becomes airborne then you want to wear a respirator/mask. Sanding it with water helps cut down on airborne particles. You may also be sensitive to the resin before it hardens. This is much more rare but some people do have sensitivity to the resin/epoxy.
Your experience and design techniques are excellent. I have learned a lot from your channel. I might be inclined to do an experiment to in which the booster slide pads hold internally onto the sustainer. Then short segments bridge from the tangnet of the booster tube connecting at a peak, letting the sustainer pass. Though, the trick is, the internal pads must keep the sustainer from rotating, which might be a issue with your design, too. If the sustainer turns axially, it may hook to the support ring of either kind. Perhaps delrin/UHMWPE or even felt or even fuzzy Velcro will make the sustainer slide nice. Perhaps the ring edges could be teardropped. BTW, you know that Freecad can use CFDof, which allows the use of OpenFoam for aerodynamic studies. It will probably do transonic, too.
Thanks for your comment. The ring geometry here is set up so that the sustainer is free to rotate on the way out of the booster and not clip the ring. The reason for this was that we didn't want to add any more gap than necessary between the sustainer and booster segments. We may loose some paint though. We could have had a guide rail on the inside, but that would have added weight and the rail buttons would have added drag to the sustainer. (The best part is no part) Thanks for the tip on FreeCad that is something I will need to look into in the future.
Hey George, it seems our last comment disappeared somehow. Hopefully we didnt violate any rules. At first we'd like to thank you for your amazing work. It inspired us (me and my son), to build our own high Pressure Water Rocket. Today we've done the first Testflights with lower Pressure and it worked out amazing. We got one question which you are surely able to answer easily... we use a hand pump to pressure our rocked right now. Thats a big struggle to even get 15 or 20 bar. In your videos you seem to use a big compressed air bottle and somehow reduce the pressure so that you are able to pressure your rocket slowly. Can you explain us how you manage to do that? That would be AWESOME! We are looking forward to finally see the horizon rocket launch!! Many greetings from germany!
Hi, glad to hear you are having fun with higher pressure rockets. :) To fill our rockets we use a scuba tank which certainly cuts down on the effort required, but a Nitrogen bottle would work just as well. You technically don't need a pressure regulator, you just need a very tiny hole in the air supply hose (less than 1 mm) that delivers air to your rocket. When you open the valve a little on the bottle, air starts to flow slowly into the rocket and you watch the pressure gauge. When you reach the desired pressure you turn the air off. It's nice and simple, but you need to make sure your pressure gauge is on the rocket side of that tiny hole.
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?
not directly water rockets but still, solid-liquid hybrid rocket, where bottom container is rigid nozzle shaped plate oxidizer and top tank is fuel, say anfo hybrid rocket. then you only need to pump the liquid fuel spray to the solid oxidizer plates and ignite/react. also gravity linear acceleration going up can do the pumping after ignition.
There's one thing that I've always wondered about water rocket nozzle design. Water is an incompressible fluid so a de Laval nozzle isn't going to help for the water phase, but what if you got rid of the water phase and instead added a tube going into the tank with inlets and an orifice such that even at the very start you'd be getting compressed air entrained with the water right at liftoff with the aim being to try to minimize the length of the air phase? You're wasting your propellant mass at the beginning by not using the stored energy from the compressed air to accelerate it faster. Wouldn't this substantially increase the total impulse of the rocket if you could balance out using the energy from the compressed air with the mass flow from the water?
Does that mean that as the pressure drops, since you are letting some of the air out early, that there is less pressure to accelerate the rest of the water that is still left in the rocket? There have been a couple of proposed nozzles where the geometry of the nozzle changes when the water runs out. That way you get the best of both worlds. One of them was a simple insert that drops away at the end of the water phase.
Hm, so, I assume when stuff is pressurized booster will squeeze sustained real good in that ring? But as booster looses pressure it will be much less compressed, though still even in template seems like it's very snug and quite "frictive" setup?
Yes this is correct. I think from the tests we did the booster segment increases about 1-2mm in circumference so let's say 0.5mm in diameter. The sustainer will also increase slightly , perhaps 0.3mm? There is about 1-2mm clearance for the sustainer between the booster segments. So yes a squeeze when pressurised and under acceleration which is good, and by the time of staging we should be back to the right clearance. The ring does have a little bit of flex under those loads so I am hoping we should be OK.
Why did you orefered to put the boosters in the middle of a segment instead into a corner of too? Maybe there is something but if you rotate it by 30° then you could have two glue line with the curved plates and it's also could stiffen the ring. I didn't checked it on comouter but also aren't it give more clearance for the fins too? The other edge of the hexagon would be where the 2nd stages fins is. Also only one glued edge would be in the "air" instead of two. Or it would require that longer panels?
This is a really good question, and it was one of the options we explored when designing it. When you have a look at the geometry of that setup and where the sustainer fins extend to, there wouldn't have been enough clearance for the fins over the entire range of possible positions of the fins. The size of the sustainer fins is fixed as the sustainer is already built. In order to get the full clearance you would have had to offset the the hexagon away from each of the booster segments. We compromised a little and the hexagon isn't a true hexagon three of the sides are shorter than the other 3.
does this hex amp weigh 398 grams? I think this is too much. You used 3mm thick plates. Are there really such heavy loads there? You have fabric. Why didn't you make the amplifier out of fabric by wrapping and impregnating a hex template with resin? I can assume that a thickness of 1mm is more than enough.
Yes, the loads on this ring are enormous. I hope even as is it is now that it is strong enough. You have a 2m long lever (the portion of the sustainer above the ring) trying to force it's way sideways during acceleration especially if the rocket has any kind of angle of attack which it will have. With the acceleration ~50G just before staging imagine the amount of force on that lever if say the rocket has a AOA of just 5 degrees and air speed of 360km/h pushing on that. Saving a few grams here isn't significant in terms of performance as the booster produces about 1 ton of peak thrust. The weight forward on the rocket also helps keep the rocket stable. Another way to look at it, sit on a bullet train and stick a 2m piece of wood out the window and angle it at 5 degrees from the direction of travel. Now hang on to it while the train gets up to 360km/h in about 1.1 seconds.
Will the ring get any face-on chamfer along the leading edge for streamlining? Or is that amount of surface area discounted as inconsequential to the Cd of the whole rocket?
No, the edge will stay as is. In the whole scheme of things this makes very little difference on the booster. If it was on the sustainer than we would probably streamline it.
George, your parachute deployment system is the best system I’ve ever seen! 3:41 If you can give me file with this parachute deployment system, please give me it🥹
Why to stack the stages inline? It's too long, I'm concerned about stability (stiff/flimsy) - aerodynamical issues. Higher weight for the structure might be necessary. Why not the short stack, with second stage being in the middle, between the boosters of the first stage? All because of the concept for stage separation and launch stand?
I am not sure I quite understand your question. The second stage IS in the middle between the boosters. Water rockets by their nature are more efficient when they are long and thin. The second stage is almost 3 meters long. When the booster accelerates at 50G trying to make sure that long and skinny second stage doesn't just tip over is not that simple. So the booster is designed to hold the second stage vertical during that acceleration. The rocket will have some AoA on the way up and the force on the second stage will be great trying to rip it sideways. We need to have the whole staging mechanism half way up the booster rather than at the bottom to make sure the whole rocket is stable. (moving the center of gravity further up).
@@AirCommandRockets Thanks for quick reply and sorry for the unlucky wording of my question. You’ve understood it well though and answered it clearly. I do appreciate it. I get the thinking behind the layout much better. I was very astounded about the length to diameter ratio of the second stage. And it seems that weight ratio between stages is a bit unusual as well. I would have expected numbers between 4 and 5. Depending on the specific impulse and empty to full weight ratio of each stage it might get outside of this interval, but I thought I saw you using some calculating tools for conceptualizing this numbers for your design. I wasn’t entirely sure if the design was a compromise between the calculations and meaningful building and operating effort of your launching set up. Thanks again, and sorry for my challenging English - I'm not native in it.
For the full 2 stage stack. With water ~20Kg and ~9.5Kg dry +/- 0.5Kg. We should have much more accurate weight estimate for the booster fairly soon. The booster weight is not that critical 100 grams here or there doesn't matter much. The peak thrust is around 1 ton. What is more important is weight distribution on the booster to make sure it remain stable throughout the entire flight with and without the sustainer.
What we find most interesting with your designs is the connection of old and proven methods like the layering of carbon and creating temporary wooden holders with all of the new stuff. That incorporation surely uses the best of both worlds. Not to experimental to have a high risk of failure but still using the weight optimization from 3d printing molds etc.
A lot of the techniques we use are just things we are familiar with or that we've seen others do. Sometimes we are limited by the tools we have as well. (We'd love to try vacuum forming for example) We do spend quite a bit of time thinking how we go about constructing something and figuring out what tools or jigs we'll need to make specifically that part. Often we are limited by the materials we have on hand. That's a part of the fun challenge. But in reality a lot of it is just guesswork with a calibrated eyeball. :)
