2 Stage Water Rocket - Part 21 - Baffle Experiments
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- Опубліковано 2 сер 2024
- This week we look at an issue we will need to address when the Horizon sustainer is flown in a 2-stage configuration. Shortly after burnout, the water in the sustainer starts moving forward inside the rocket which can lead to a loss of performance if the rocket was staged some time after burnout. So what are our options?
Ullage motor video:
• The Ullage Motor: Smal...
Inside tank video:
• Falcon 9 LOX tank cam - Наука та технологія
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Rocket: *explodes*
George: *repairs it*
Rocket: how many times do I have to teach you this lesson?
I just love that you guys just put a test article on one of your actual water rockets to see what happened
Great Video!
Interesting way of irrigating Australia;)
Just kidding. Love the perseverance of your science. One day you will reach the Kaman Line.
"Right after burn out, before the deceleration really starts..." The deceleration will be at its highest right after burn out.
That is correct. I was meant to say ... before the deceleration really starts taking effect..
I suspect the remaining air pressure will give it a small kick
It's actually a little more than a small kick. About 1/3 of the total impulse is generated after the water runs out and the air starts coming out.
@@AirCommandRockets How many Gs does that put on the structure? That's gotta be peak load right there
That's right, the peak acceleration happens just as the water runs out, the rocket is at its lightest and still has high pressure air accelerating it. For the Horizon rocket, the max acceleration at this point (at the intended pressure) is around 82G.
Well done, a very informative video! This problem can be a major headache in large rockets since the moving fluid can cause the rocket to change trajectory and fail.
Thanks Daniel, that's a good point. I think we've seen that in some of our rockets as well, where they fishtail a little after staging, perhaps the slosh is upsetting their center of gravity in relation to the thrust axis.
Great video, I can’t wait for Horizon’s 2 stage launch.
Thanks Laurence. :) Thank you for the drone footage :)
Air Command Rockets No problems, glad to help
How about a fine mesh at the water level?
The surface tension of the water would keep it from going up ( unless you want to add soap).
That's actually not a bad idea. We would have to have a look at how much that would impede the air flow, but it may be workable.
Alternatively you might also look at the kind of sponge material that is used in vacuum cleaners to filter the exhaust air. Or a valve type of closure, like a heart valve.
Interesting. I think while a sponge like material would totally work to stop most of the water, it would also significantly impede the rest of the compressed air after the water runs out and it may blow out the sponge. The pressure chamber gets emptied in several hundred milliseconds. Perhaps a dual plate check valve like this would work: cdn.hardhatengineer.com/wp-content/uploads/2018/06/dual-plate-check-valve.png
@@AirCommandRockets While a valve might work, a mesh is by far the lightest option. There are different mesh size to wire thickness ratios available so you could chose how much area is blocked. Maybe something as simple as a glued in paper towel might work. The towel would be ripped out as soon as the water starts flowing, but retains the water during decelleration.
But it would be a giant mess to tape in for every launch.
Excellent 👌💓👍👍
How to make boosters ?
Are you allowed to have a small nitrogen pressure buffer on board? Would that help?
Food for thought: Could you put an expandable foam slug coated in a hydrophobic layer? It might be added easily to the already built sustainer by crushing it down, letting it expand, and pushing it to the desired position. The water won't pass through the hydrophobic sponge when upside down. The sponge will be blown out, in pieces likely, with the air and water during launch. Not sure how a sponge material behaves at 1200 psi.
How does it seperate?
could a hollow gutter shaped baffle improve it's performance even more, redirecting the water that's back downwards?
idk how to propperly describe it, like a hollow donut cut in half with the hollow part placed downwards toward the liquid.
or is the conical shape already enough to make that happen?
That was kind of our thinking with the conical shape as well. But I understand the design you are describing.
Scotty... :-)
Logical thought: Perhaps the two parts that failed were put on the rocket at about the same sort of time?
Pls show how to make this simple water rocket at home
Is there any good place to purchase polycarbonate FTC tubes in Australia? they seem a little hard to come by
Have you tried going to a lighting store? They can order them in for you.
@@AirCommandRockets Thanks!
Am i missing something. why not use a flap inside the sustainer. simple easy to attach. when flap open due to positive g. almost no impeding flow and when shut due to negative g the flap shuts completely.. you could also make the flap curved so it fits neatly into the edge of the sustainer when folded??
Could a buffle made with more then one hole work?
Yes, quite possibly. One thing we have to be careful of how that will affect the internal air flow after staging.
Great experiments guys! Thumb up!
How about using a thin membrane instead of baffle in the container? The membrane could be held in place with rubber or plastic ring just above the water line, and when rocket section is released, air pressure simply breaks the membrane or blows it out through the nozzle. The membrane could be made with regular plastic wrap, I think, and could help to solve problems that baffles add, including some water displacement and performance decrease. Just a thought. I hope this helps. Cheers!
Cheers, there are two issues with a thin membrane approach. We need to turn the rocket upside down and fill it with water. This would probably break the membrane. And when the rocket is back up on the pad the right way around, we need to pressurise it. This is done through the nozzle. So this would also break the membrane before launch.
@@AirCommandRockets Thanks for replying. Forgive my amateurish thinking :-) I wasn't following your projects in detail.
I just think rockets could be pressurized from the top through a valve, and filled with water from the bottom before pressurizing. Membrane would be safe with release mechanism closed and holding the water in place.
No worries, this stuff is fun to think about. One problem with filling it with water from the bottom is that the air compresses between the surface of the water and the membrane. You would have to be simultaneously pressurising it from the top to balance this compressed air. Any pressure differential could burst the membrane.
@@AirCommandRockets It all comes down to what is most practical and safe for you.
I was thinking about filling the volume between the nozzle and the membrane with water first when rocket is upside down, and then closing the nozzle. Pressurizing with air from the top would be the last step when rocket stands up. Even if some air got trapped in the water section, it wouldn't cause problems as water is practically incompressible and plastic membrane could stretch a little without bursting.
Plastic wrap, like type used in kitchens, is quite strong and could support several liters of water with no problems.
My "experience" comes from the water gun project I built several years ago to deter backyard pests 🙂 Water section had its own inlet. After adding water and closing the inlet, the gun was pressurized through a simple tire valve. Of course, it didn't have any membrane inside and operated on pressures nowhere near what you guys do, but was fun and easy to use. That's why I wanted to mention the idea of separate water inlet and air valve.
Thanks again for replying and share the fun with us! 🙂
Have you looked at using a Tesla valve for the second stage?
I think a pause after burn out is the best way. even after burn out the rocket is still going up. But indeed it's critical to know when the g-forces are going down again. thats no problem .. the problem starts when it wants to tip over and fall back to earth. On that note. there are tiny g-force / acceleration sensors.. will add some complexity. you already have some electronics / camera in the nose a few more grams to actuate the release should be no problem .. I know i know im just a arm chair rocket observer :-)
The issue happens very shortly after burnout, well before you get to apogee. You actually get -ve G while still going up as can be seen in the video. Watch the water and the horizon in the background. Here is a little more information on that: ua-cam.com/video/umtG_zMYTok/v-deo.html and ua-cam.com/video/oC8AbWXFiTw/v-deo.html
When I built a two stage rocket (many years ago), I used a balloon as an internal bladder to keep the water from moving up during the free fall period. Would this not work for you?
Did the rocket then eject the balloon through the nozzle?
@@AirCommandRockets Yes. The excess pressure blew the balloon out of the nozzle and I seem to recall it was often inside out or shredded.
What if the top 1 mm of your water is actually gelatin? I wonder whether such a trick is possible...
I have an idea, separate high pressure air and water using ballon .l mean ,fill balloon full of water and no air on inside balloon. Get insert watered ballon in the bottle and give pressure directly to the bottle . This separate water and air from mixing . Set the ballon hole to cap very careful.I thought it will.
If you can done it , make a second video on this topic .
I am waiting for your reply 🙂
You would have to eject the balloon through the nozzle so the rest of the pressurised air can also get out through the nozzle. About 1/3 of the total impulse comes from the air-phase portion of the thrust.
I am the same guy (infinity editz).
Use small water Ballon to hold small amount of water close to the nozzle and other water outside the balloon. When the rocket seperate at midair water in balloon escape first and then the balloon explode and release water left in the bottle and where the main thrust come and you will get max thrust without losing pressure but pressureise rocket threw nozzle not possible if balloon is connected to the nozzle.
You should try using a sponge as a baffle that’s what we use in tanks of race cars and bikes to stop fuel running away from the pick up pipe
What kind of a sponge is it? The requirements here are that about 5 liters of air at 1000psi need to pass through this sponge in about 0.5 seconds.
I guess the baffle doesn't need to stop all the water, as long as the water that does get past it falls back down before the air pulse. Is that why the baffle is angled downward, to let the water run back down?
Yup, we don't necessarily need to stop all of the water, just most of it. As soon as the rocket is released, any water above the baffle will make its way down quickly. And yes, that is why the baffle is angled downward to allow better flow of water and air down.
Man, it is really foggy out there. Keep safe you guys.
That ain't no fog. ..... :(
@@AirCommandRockets I meant to say haze. Fog, smog and haze are interchangeable in my place. Nonetheless, keep safe.
I have an idea💡 separate high pressure air and water using 🎈balloon. I mean , fill balloon full of water and no air on inside balloon. get insert watered balloon in the bottle and give pressure directly to the bottle . This separate water and air and stop moving from their position.
Did you like this, please comment
Does it have any problem in my plan, reply the problem
В космос на ней не улетишь, а вот для военных полезная разработка. Топлива не надо. Воды налили из пруда. насосом накачали (можно духов заставить) и огонь батарея
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