Great video, George thank you. Rebounding from failure is one of the hardest lessons I have to teach my STEM class so I'll be showing them this as well as the ultimate success I know you'll achieve.
Thanks for that. We actually see the failures as a good excuse to build more rocket bits or do experiments. :) The main thing with failures is trying to discover the root cause of exactly why something failed, rather than just guessing. One of the things we considered here was to use coloured dye in the water to see exactly which path the leak was taking through the neck, but it would have meant we needed to cut it open. We want to try to save the pressure chambers though so we have to do a different approach.
Thanks for that. Yup chasing down the different types of leaks has been the biggest issue we've come across, though I think this is really the last of them (in the pressure chambers at least) Hopefully we can repair these existing ones and can move on to mounting them together.
Hi there, thats quite amazing, my son and i have been watching your videos and we are making our own rocket with your first designs in PET bottles. We send you all best wishes from Mexico with this great proyect and hope see Horizon flying high soon.
Cheers good sir for posting so much on the rocketry discord, you're truly an inspiration with your comprehensive information. Looking forward to your next vid.
Thanks, I hope the solution we have in mind will work to repair these pressure chambers. But we're happy the rest of the pressure chamber is fine and can contain the pressure without issues.
I have a couple ideas on maybe how to make the high pressure tanks less likely to fail. First would be to put the tank while the resin is unset under a bit of vaccum to degas any air bubbles in them, second, put them under pressure to shrink any remaining air bubbles as resin sets. Third maybe a step up on the second. Put a bladder (maybe a rubber hose?) in the tank and pressurize it, forcing resin into any voids and maybe also squeezing excess out, perhaps in a two part clamped pipe. The third may need a mold release or a plasic sheet layer? Just putting it in a pressure tank as they set would likely be easiest and a large steel pipe with end caps with a hanger should work. Thanks for bringing us on the journey and may they fly high.
Magnificent work as always! My two cents the leakage problem: The pressure compresses the outside of the aluminium tube so its diameter shrinksr. Then the water can creep between the aluminum and the carbon fibers. A possible solution might be to flair out the inside end of nuzzle in a thin cone and then get the structural layers on the inside as well as on the outside of the aluminium. With this the internal pressure will never be able to go "around" the aluminium and will always force all layers to expand in the same direction.
On the sustainer the aluminium nozzle does have such a flange on the inside and it does not have this problem. The main reason for the flange though was to stop the nozzle from being pulled out under pressure because we hold on to the nozzle. In this booster we aren't holding the booster down by the nozzle and so we didn't think the flange was that necessary, but it looks like it may be. Too late for these segments, but we do have a plan for repairing them.
Really cool to see the progress of this project! Nozzle leak must be annoying but i have no doubt you guys will figure it out. Cant wait until the next video!!
Cheers ARRO, yes quite annoying, but we're still having fun. :) The leaks are just a part of the development process. Next video in the series is currently being edited. :)
It is nice to see that the booster is coming together. Very satisfying to watch! One question: what is the advantage of your approach over drop-away boosters?
Thanks Dan. Doing it this way gives us a true 2-stage rocket that fires the second stage when the first stage has finished producing thrust. With the drop away boosters you typically fire the main stage at the same time as the boosters. The boosters just need to produce greater thrust than the main stage to keep them in place. We expect the second stage will be fired at an altitude of perhaps 200-300m?
Thank you for taking us all with you on your journey & its tribulations. Some wonderful engineering. How many more steps will it be before we see the first flight?
Thanks for following along. :) We thought we were going to be done with this project a couple of years ago. Hard to tell how much longer, but we are making forward progress. We also have limited launch opportunities during the year to launch so it will depend on that as well and weather co-operating.
You chaps are amazing. My thought is that the aluminium nozzles should turned with a large flange at the top like a funnel so that the water pressure pushes it against the inside of them carbon fibre endcaps helping the seal. I have no idea really what I'm talking about and have faith that your solution will work.
I agree I think we should have made these nozzles with a flange like we did for the sustainer. The sustainer nozzle had a sizable flange and it didn't exhibit these kinds of leaks. We had the flange there mostly to stop the nozzle from being ripped out because it was holding down the entire rocket. On the booster we didn't think it was necessary as the aluminium nozzle is there only primarily to give a tight tolerance seating surface for the o-ring in the nozzle seat. The booster is not held down by the nozzle. Definitely on the next ones we make we'll put the flange back on. They are just a little more tricky to machine.
Interesting leak problem... Have you thought about using the higher stiffness of CF to replace the individual tows of GF that you wrap around the ends to reduce expansion? Alternatively using unidirectional tape instead of individual tows might see some improvements (although that's possibly just a more expensive way of doing what you're already doing...) That's assuming that the movement of the laminate under pressure is causing the delamination as the hoop stress in that area overcomes the part. Looking forward to seeing what you come up with.
I think what would help is if the tow was really tensioned when applied to the pressure chamber. I am guessing that un-tensioned as these are, they are probably still stretching a few %.
Maybe I wasn't watching carefully enough, but was the aluminum/carbon interface smooth? Or did the aluminum portion have some texture, grooves, ridges, etc to improve the bond at that interface?
Maybe make the end caps solid. Drill them out and thread them with a tapered pipe thread. I would also consider 304 or 316 stainless steel for the nozzles. Aluminium is quite prone to plastic deformation.
Threading the nozzles certainly is an option, and is one of the things dad and I talked about, I don't think we had an issue with deformation of the nozzles here, I suspect the carbon fiber around the neck pulled away from the nozzle under pressure. It only took the tiniest delamination for the water to sneak through.
Still fun. May I ask, is there a reason you did not wind the tank similar to how small composite tanks are made for things like paintball and such? Why Al of the hand lay up?
That's a really good question. We do not have a winding machine, and to get one up and running that can make pressure chambers over 2m long is not cheap. Perhaps one day. :) The inner pressure chamber would still need to be assembled from 3 pieces, but the external wrap could be done with a winding machine rather than with a sleeve. We will probably get vacuum forming equipment first before we get a winding machine though.
Hello, I'm follow you from France, so sorry for my English. I just have one question about your booster. What is the reference of your carbon fiber sleeves ? What you doing is very exciting, so thanks for your video
Great work, I love what you guys are doing! Since it seems like you have the aluminium in contact with carbon fiber, I wonder if the leak migh be caused by galvanic corrosion. Although maybe enough time hasn’t elapsed for that to become an issue.
There is a layer of epoxy between the carbon fiber and nozzle,, but it is possible that the carbon is in contact with the aluminium at the ends. Galvanic corrosion could be a factor at some stage.
Good question. We would hope to get several flights out of each. But will be happy if we even get 1 flight out of the booster. We have done I think 3 or 4 full pressure cycles of one of the test pressure chambers to make sure that is the case, but you just never know if there is a particular flaw in any of the specific pressure chamber.
would it be possible to coat the inside part of the tube with some form of polyurethane resin that remains flexible and is compressed into the leak? I think if the aluminium nozzles are flared out and thinned out, it may help protect against the leaks as softer aluminium would be compressed agains harder carbon fibre tube
We considered some kind of internal coating at the joint to try to seal it. We even did tests with the water proof membrane paint used under tiles in bathrooms, but because the aluminium nozzle is so thin, trying to get it to stick well enough to the edge wasn't reliable. The other issue is that the gap really only opens up under pressure. You are right having flanges on the nozzle would have been better. We did that on the sustainer and didn't have these issues.
A video from this series popping into my inbox is like Christmas! Awesome progress. Will you fly just the booster for the first test flight or will the first flight be a full stack?
Cheers, thanks for following along. :) Nope the booster will fly for the first time in the full stack configuration at the full intended pressure. We are not sure how many flights we are likely to get out of it, so it will be an all or nothing type of flight. I find it funny how much time we are spending building this booster, and it's job will be done after a couple of seconds.
Hi George. I've been watching your videos for more than a year now. Great work! It seems to me that the expansion of the pressure changer is the issue. Since the fiber goes around the outside of the aluminum nozzle, which pretty much doesn't expand at all, they separate from each other, and the water finds a way out. I was wondering why don't you try to change your nozzle, making the fiber go through the inside of an aluminum ring. It will be tricky to build it, but I am pretty sure you will figure it out. Hopefully, that will solve the issue. Good luck!
Aluminum is quite reactive and you should be able to drill out the majority and dissolve the thin remaining shell in lye or some other caustic that doesn't damage the epoxy. Then make new inserts, my gut tells me that a U shaped lip that sandwiches the CF will give it a lot more surface area to seal, and any expansion will be working in your favor to tighten the contact of the outer band rather than loosen it.
This is very close to what we want to attempt. We've already got the drill bit ready to drill out the aluminium nozzle. We too discussed using a caustic liquid to dissolve the aluminium for exactly the same reason you mention to not affect the epoxy. We will do some practice on the test pressure chambers how easily we can remove the nozzle. We are also likely to ditch the insert though, and fill the whole nozzle with epoxy, then drill out a new hole into that. We've made a custom drill bit for that as well. First though we'll test if an all epoxy nozzle will work and seal properly.
@@AirCommandRockets Good to hear. I was going to suggest using all epoxy, but didn't know enough about the seals to know if it would be reliable. Metal always seems more trustworthy, but I always underestimate other materials. I was also going to suggest (counterintuitively) using slightly elevated tank pressure when seating whatever you end up using, if done with bracing and a sacrificial front seal that is removed after the cure. Once the epoxy starts setting up and with the right amount of pressure it may help establishing a better seal. I can also imagine standing the tank vertically, putting in a release covered insert of the correct diameter with a pressure fitting, injecting epoxy and letting gravity pool it around the junction, then slowly ramping low pressure over time.
Hey I am currently building a water rocket using spliced smartwater bottles reinforced with 2 layers of fiberglass to achieve 300 psi or more was curious what the gross wieght of your rockets...
Hi, sounds like you are having some fun. We build all sorts of rockets so the gross weight is really going to vary. Here is a long list of most of our older rockets with all the details including capacity, weight, pressure etc with an associated picture for reference. www.aircommandrockets.com/rocket_gallery.htm
@@AirCommandRockets ok so if you wanted to do multiple layers, and using sleeves, could you put several dry sleeves onto of one another then wet it all out? Thanks again
@@callum22 The more dry layers you put on the harder it is to fully wet out, unless you did something like infusion. You end up with quite a few voids between the fibers. Perhaps consider using a heavier sleeve like 12K instead of multiple lighter sleeves. Also if you are trying to pull sleeves over one another, make sure the inner sleeve is well attached at the end that you are pulling the outer sleeve over. If it comes undone it's not going to be pretty.
Sorry to hear about the leak woes. We all know you and your dad have a lot of thought into the build process! Hopefully you can engineer a repair solution, but if a complete re-build is necessary I wonder if this video link below might provide any helpful insights on improvements. This rocket builder talks about doing some surface prep testing to ensure chemical bonding of epoxy. From what I see in your videos you seem to have it down really well, but maybe there's something in the video that can help. Can't wait to celebrate your 2-stage launch success! This is an amazing project to watch unfold! ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-ttqEsg7qf_w.html
That is a good question. As a 2 stage rocket, if everything goes according to plan and the rocket flies vertically then we are hoping for somewhere around the 1.2 - 1.3km range.
I wonder if you could put a non dissolving powder into the water to plug any pin hole leaks...(ground pepper, aluminum powder, copper powder, baby powder, gypsum powder...)
Interesting suggestion, though I think even tiny holes between the particles would let air through. Then if any pressure gets in between those particles when the pressure chamber quickly depressurises, it is likely to blow those particles back out of the crack.
Ok Well that definitely gave me some ideas of if I'm in the ballpark or not I'm my rocket's gonna be 4 later capacity I'm going to do point 8 of a leader at 300 pounds it's 80 mm in diameter it is 36 inches long but it's for 4 leaders and my driveway I'm trying to keep it at least at 500 g at no less I notice that when I do the water rocket calculator online it shows that a 100 grand rocket doesn't go as high as a 500 g rocket because of the inertia of the weight I'm assuming But I did it several times and more weight on some rockets actually gets a higher altitude because of the amount of drag on something light like a feather you know
Exactly, there is an optimum weight for all rockets, some simple water rockets come in at a lower than optimum weight, so adding a little more weight will make them go higher.
Hi guys, Did you see this video on Firefly Aerospace? ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-ac-V8mO0lWo.html They are building LOx and Kerosene tanks out of carbon composite and their process is actually pretty similar to yours (but bigger...)
There you are just building huge rockets with carbon fiber, here I am postponing cutting a 6mm carbon tube in two for over two months because I'm afraid of the carbon dust!
