Making a simple barometer
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- Опубликовано: 30 сен 2024
- This week we do a couple of follow up experiments to the bag inflation experiment performed a few weeks ago to see if we can make the barometer more sensitive to the small pressure change as the rocket goes up.
We flew it a couple of times on our regular water rocket.
In the video you say the pressure in the can increases pushing the water out. Technically the pressure stays the same and the outside air pressure is lower as the rocket goes higher. I know this is picky but if any would be science majors are following this a correction might be in order.
I use to fly R/C gliders in college in the 80s and we heard of a method to make a detector to figure out if you were going up or down thus making finding lift via thermals easier. It used a fix volume not unlike your experiment. There was an opening in the volume with 2 pieces of wire that had current passing through them in a bridge arrangement like you would use with strain gauges back then. The wires were high resistance and heat up. Since these wires were in the opening of the volume you could tell if you were in sink or lift by seeing which wire was cooled (and thus changed the wire's resistance) by the air flow into or out of the opening to the volume. The bridge balance current could be used to feed a transmitter with a constant tone that shifted up of down as the bridge balance would change. We tried to build one but we never could get it all small enough for the gliders. We were ME students not EE so that didn't help with getting it optimized as well as poor college student syndrome.
Ooops, you are quite right of course. Thanks for pointing that out, indeed the pressure doesn't rise. It would only rise with increased temperature. Really interesting description of the wire sensing mechanism to determine air flow direction. Thanks for sharing.
I reckon you could read pressure directly from the water if you calibrate it and put markings on the clear tube, but altitude will need to be calculated from pressure separately since it doesn’t go up and down linearly relative to the pressure. I’m sure it’s possible to get a pretty accurate altitude estimation with enough water trickery.
Seems that this design is far from functional.
MY suggestion is a syringe, a really fine bore tube, and a light oil like mineral oil.
VISUALS will be MUCH LESS...
But PRECISION will be MUCHMORE!!!
[OTHER UNADDRESSED CONDITIONS, STEPS, and SITUATIONS MAY HAVE ALSO IMPEDED the accuracy...]
Great to see that this worked really well!
I'm curious why the water didn't go back at the same rate during descent.
Maybe the lid is not as airtight, as it should be?
Good observation, I noticed that too. I am wondering if the orientation had anything to do with it, perhaps it got more sun being on its side and the internal temperature rose a little.
Have you ever thought of designing a steam rocket?
That's never been on our list of things to try mostly because super heated water and kids generally don't mix well. It is also unlikely we would be able to launch something like that at one of the club launches.
I wonder if there is a way to use a water rocket to measure the atmospheric voltage gradient? I am not saying fly in a thunderstorm (Although this would be some great footage...), but the higher you get the more positive ions there are and this can produce significant voltages that you can measure with a Franklin Bell or an electroscope. The only practical problem is that you would need to connect to ground (or have some other source of negative ions?) - which would require you launching with a thin wire connected to the rocket.
It would be interesting to measure the static charge a rocket accumulates in flight. If you needed a ground reference you would probably need to unspool the wire from the back of the rocket the same way a TOW missile does it. I wonder if you would be able to detect any voltage across the length of the cable as the rocket falls back down through Earth's magnetic field. (If the rocket lands some way from the launch point so the cable is more stretched out)
Yeah I was thinking something like that. The unspooling would look great on its own - I'm not sure what the range safety officer would think of this idea!
@@simonabunker *waves hand* .... these aren't the cables you're looking for.
Recently I've got into water rocket building and your channel is simply a treasure of knowledge !:) It looks like you're using scuba tank to pressurize rockets. May be you could show your system in more details? Like, which regulators do you use and high pressure lines, stuff like this. Even with relatively low pressure launches with kids pumping the rocket becomes annoying pretty quickly:))
Again, thanks for sharing the knowledge, it helps so much!
Hi, do you think a 2.5" 3k carbon fiber sleeve would fit over an 2.7" tube
Should be just fine.
@@AirCommandRockets thanks
That was great. Always love your content George.
Cheers Darren :)
I like to use the phrase "That is no rocket sience", if I think, that something isn't too complicated. But in this case, it is "rocket sience".😀
Connect a computer to the camera output to detect apogee and make the most baroque dual deployment altimeter ever!
Im having trouble making my rocket stable, any tips on how to have a dtable rocket?
Put your fins as far back as possible. Add some weight to the tip of your nosecone. If it is just a single bottle rocket, add perhaps 50 grams to the the nose. What is your rocket's current configuration?
@@AirCommandRockets i have a 1.5L bottle, and have a bit of weight in the nosecone, my fins i calculated to get the right size
@@SnarkyRattleTrap Where are the fins mounted on the rocket? For single bottle rockets, they normally need to extend down past the nozzle. Hard to make recommendations without seeing the rocket. Also is the rocket unstable throughout the entire flight, or just during boost? If it is just during boost, try reducing the water amount to 25%. Do you use a full bore nozzle, or a restricted one? With restricted nozzles you have more weight near the bottom of the rocket for longer and so it tends to be more unstable. I would just add more weight to the nosecone as the simplest solution if you can't move the fins back. How did you calculate the size/position of your fins?
@@AirCommandRockets i could definitely try moving the fins longer back, as of now they are in front of my nozzle, thanks alot for the replies, and i love your videos!
This was such a cool experiment! Must be handy having so many ultra-reliable water rockets where you can just fit all sorts of experiments in, can't imagine it being nearly as practical (or inexpensive) in a similarly wide or spacious pyro rocket
Cheers, I agree a water rocket like this does give plenty of opportunity to fly experiments cheaply. This water rocket flies on an equivalent F motor.
I am Hyped to watch that after work.
I want to know the diameter of the pvc pipe used as a 2in carbon sleeve mold.
60mm
Now make a pitot tube!
unrelated to the video but im trying to make a water rocket and i shoot it up and i put in a fall away nose cone along with a jolly logic chute release i launch it and once it reaches apogee or highest point the fall away nose cone just does a nose dive in to the ground. its a basic water rocket so it goes sub 200 feet. the chute release does its job and deploys the chute but the fall away nose cone doesnt fall of so it just doesnt deploy and slow it down. (i tried weighing down the bottle neck of the fall away nose cone but it made it worse. (if anyone could help i would love some help)
I am not quite sure I follow. You have trouble getting the nosecone to fall away at apogee? This can be very unreliable. Just curious if you have a JL chute release, why does the nosecone need to fall away? You can set up the deployment with just the chute release so the parachute is ejected sideways.
@@AirCommandRockets im going to try to use a mechanism that uses a tomy timer attached to a rubber band that realeases a chute door. i didnt realize that it doesnt work alot i just saw everyone else doing it lol
Hey how many minutes to make thrust 1 min? 3 min?
I am not sure I understand the question.
@@AirCommandRockets how much pressure to make thrust
@@AirCommandRockets i pump for 5 minutes
@@Colossaltitannwkwbend How long you pump for depends on what volume of air your pump can pump per minute, what volume of air you are trying to fill and what pressure you are trying to get to. Let's say your pump can pump at 1 liter per minute and you are trying to pressurise a 2L bottle to 10bar. Then your pump needs to deliver 20L of air which will take 20 minutes to pump. If your pump can do 2L per minute then it will take 10 minutes to pump.
How much thrust and for how long that thrust will last depends on your pressure, volume of pressurised gas, and the size of the nozzle.
@@AirCommandRockets okay
Hey man, lovely rockets, not so lovely Nestle Product.