Experiment to see pressure drop in flight

We perform a simple experiment to see if we can visualize the pressure drop as a rocket ascends, and then see the pressure increase again as the rocket descends.

You need to multiply the effect by having large rigid container with small flexible one attached to it. It could be bottle with small circular hole and clingwrap glued over it

[@AirCommandRockets]

Yes, I think something along these lines would work.

[@adammckay7335]

Maybe a bottle with a small syringe in the end. You would need a syringe the moved freely. Then the percentage change on 1% would show on a 2 ml syringe for a 200 ml bottle.

[@AirCommandRockets]

I'm thinking something along these lines too. A stiff walled chamber with a small indicator on the end of it so the volume change only happens there. I was thinking the indicator could be something like those rollup party horns that unroll as you blow into them, but just a really light weight version.

[@ascensionrocketryshorts]

A very interesting experiment to a question we never asked us but if thought about is very interesting! Keep doing these experiments, they are very interesting.

[@AirCommandRockets]

Cheers :) We plan on doing a follow-on experiment on this one based on the suggestions from people.

[@g.j.647]

For me, this is water rocketry of it's finest. Ingredients: Freezer bag, foam, camera. Tools: Sharpie, flat iron, scissors. Must have: Ingenuity. Reminds me of "Skittles in Microgravity", "Liquids in near-Zero G", "Dual Thrust Water Rocket " and the one and only "Dropping toilet paper rolls from a rocket". ... and keep your sense of humor.

[@AirCommandRockets]

Cheers for following along :) Dropping the toilet paper was good fun.

[@q300SBB]

Love your work George.

[@AirCommandRockets]

Cheers :)

[@blacquejacqueshellaque6373]

Restrict where the bag can inflate so all the change is in a small location.

[@daninvents3652]

Being an electronics nerd as I am I would be tempted to build a sensor by combining a syringe, a strain gauge, an instrumentation amplifier, an ADC and a microcontroller for data logging :)

[@AirCommandRockets]

Now that sounds like a challenge :)

[@carlostph]

The effect is spread out over the surface of the bag. A rigid bottle with a water balloon attached to it's mouth should do the trick. All the displaced air would be confined into the balloon.

[@AirCommandRockets]

Yup, I too realized only after reviewing the footage, that we need a rigid chamber with a port that we can connect some indicator to. We will try something along these lines suggested by you and others that have commented.

[@_Creativo]

a cool video to watch while eating

[@AirCommandRockets]

What's for lunch?

[@_Creativo]

@@AirCommandRockets tacos 🌮🌮

[@_Creativo]

btw nice experiment George

[@What_I_Make]

Instead of the bag inside, use a flexible seal at the external holes, the pressure difference at the small holes will be a very small percentage and should see a reaction at the hole expanding and contracting (Maybe). A single small hole instead of number of small holes mean the video can focus more clearly on a single event.

[@marcdubois8601]

Just an idea! I'm curious about the G force on the acceleration on a simple water rocket! Maybe you already did a video about this that i miss!?!?

[@simonabunker]

You probably need something like an analogue altitude meter where the small movement is amplified by the distance it moves at the end of a long needle. One way of seeing pressure change is with a u bend of water being pushed, but i don't think that would survive the flight well - especially under acceleration / zero G!

[@AirCommandRockets]

The U bend with water in it may actually work if we perhaps instead of a simple U, we loop the tube around a few times. I also think we could mount it sideways so that acceleration forces are perpendicular to the tube and the tube is narrow enough where the surface tension prevents it from flowing out. I think this is something we could also test on the next attempt.

[@simonabunker]

@@AirCommandRockets are you going to test any of these on the ground? You don't really need a good vacuum chamber. Or just send it?

[@AirCommandRockets]

@@simonabunker We'll just send it. Any excuse to launch a rocket will do. :)

[@davidbrett1958]

A solid plastic container with a balloon pulled down over the container and taped around the top.

[@cklcat]

A astronaut inside the rocket will be useless

[@George-zi9jz]

My brother had a winch launcher for sailplanes.. gliders.. The winch takes gets the aircraft to about 1,000 ft, release and then the pilot searches for lift or return for landing. If they could get an additional minute + - of thrust, maybe a few hundred feet higher, they might have a better chance of finding thermals.. Using a 2 seat glider with only one pilot., Is it feasible to use a nitrogen or oxygen bottle, a few gallons of water and nozzle to discharge after winch cut away? 170 pounds is about the weight to work with. After the discharge and the few gallons of water are gone, the sailplane would be much lighter, only carrying the weight of the bottle, tank, plumbing and nozzle system... This idea has been kicked around for years, and it looks to me like you are experienced enough to consider it. thank you... George

[@AstroBananna]

Awesome video, black out the compartment holding the experiment and use illuminated camera, be nice to only focus on what’s happening to the bag instead of fluctuating light conditions as the rocket spins and moves about.

[@AirCommandRockets]

The idea was to be able to have a direct reference of where you are in the flight. If we black it out we would need to include a second reference of perhaps a logging altimeter, or a second camera on the outside. But perhaps we can black out just a portion of it where the experiment is, and see the world around the periphery.

[@lloydbush]

Maybe fill it with a gas, that has a higher expansion ratio.

[@hoagy_ytfc]

Is the temperature gradient over that delta altitude small enough to ignore?

[@AirCommandRockets]

This is a really good question. From previous experiments the temperature difference was perhaps 0.5C so not a lot to worry about, but certainly for higher altitude flights that is something that would need to be taken into account.

[@1itim]

Go higher

[@Speed_Goo]

cool❤

[@brunom3478]

At what pressure did you launch?

[@AirCommandRockets]

110psi (7.6bar)

[@tasesq]

For reference a bag of salt and vinegar chips bursts (and scares the crap out of you) at around 8,000 ft.

[@AirCommandRockets]

Personal experience?

[@tasesq]

@@AirCommandRockets yes! At 3am by myself on the way back from Mildura 🤣

[@nerdtronaut]

An Arduino with a bmp280