Liquid Rocket Engines 7: Tanks and Capacitors

Hi Rocketeers!
Today we're talking about the tanks and test stand mechanical design from my new workshop in beautiful Colorado.

[@CopenhagenSuborbitals]

Why is everyone making videos on propellant tanks this week?? Including us!

[@vishalk4647]

Get ready cause that's what we're working on here haha guess everyone's planning of owning rockets like cars😂

[@CopenhagenSuborbitals]

@@vishalk4647 The more the merrier!

[@vishalk4647]

@@CopenhagenSuborbitals exactly plus seems like space flights and launching satellites would be getting quiet affordable for more people to walk in this beautiful field of art and science.

[@psyxiatros1]

@@vishalk4647 my 2 cents worth is this: Drones became popular and suddenly there were 1 billion rules and regulations to restrain their use. Actually what the law makers worlwide are trying to do is to prevent people from using drones. Imagine now what will happen if more and more people will get attracted ? familiar ? interested ? involved ? in rocketry which already has 1 billion rules and regulations and its already half a way to make a weapon. I m sure that they will soon make it impossible to even think about going that direction. If dreaming is free then tax dreams and nobody will dream anymore.

[@vishalk4647]

@@psyxiatros1 there are 200 or so startups every year pitching up for the same field and fortunately only a few actually gets the vitamin m grow up into an actual company. Check up on KZbin tons of people testing stuffs but thing is people know making a orbital or suborbital rocket isn't anywhere close to making a model rocket or small demonstration engine. Drones are no longer a new technology except for the ones defence forces uses. You're right while saying it's half way to make a weapon and that's why not everyone gets the knowledge of how it works from an expert unless you're from the same country and same field and prove your capabilities.

[@CanineDefenseTechnologies]

I think it's pretty ingenious to use beer kegs. I always thought looking for parts from a different field with the same specs that cost far less for rocketry would be great, and this is a great example!

[@Ameliaross106]

Waited for ever for this one yay

[@robertsteinbeiss8478]

Good ... yes good!

[@OrionAerospace]

Keg tanks and the engine is running on ethanol 🤔 I sense a theme Great video man! You’re presentation skills have dramatically improved and your personality is coming across real well! Can’t wait for more

[@robertsteinbeiss8478]

That is a Business Idea, Engine Test at day pressure fed beer stand at night. Cold Lager, strong ale and ... cheers at the combustion chamber!

[@Heikakyu]

Charlie is getting more confortable with the camera, I guess that's one side effect from 'Cooking with JoeyB'

[@maxhaynes677]

Welcome to Colorado! Should come out and visit the northern Colorado rocketry club, been flying with them for over 7 years

[@zachm4635]

Hoping this series comes back soon🙂

[@Thorgon-Cross]

For my first bi-prop engine (was only few N) I used a old chemical fire extinguisher, the type that hang on the wall. For the 5Kn engine that I have been working on I was planning on using a stainless steel water fire extinguisher, they are rated to the 300 psi, that I am planning on using, also are hydro tested to 500 psi. I like the idea of beer keg as it will allow me to have a longer burn time.

[@jborgesss]

Thanks for the video Charlie. The beer keg idea is very interesting!

[@robertsteinbeiss8478]

I hope he bought some full ones, that would be "Cooking and Drinking with Charlie"!

[@pedrogmiller]

A beer keg?? Badass!

[@martinnourry9109]

Good to see you're back Charlie!

[@Starman5771]

Charlie is just getting stud day by day🤣🤣🤣🤣

[@15gamershaven89]

Glad this series is still going

[@whcolours9995]

Y'all ever feel bad for wasting a small amount of this lad's time on Twitter, while also having a vine play through your head once you heard "Giraffe"? Just me? OK Anyway, fantastic series so far! This'll be plenty useful for amateurs like myself!

[@hene6539]

Nice work. Keep it up!

[@SurfyKirky]

Been great watching your videos, I hope you make an open source schematic. I’m learning a lot from watch yours and others videos but it’s so bloody hard to have the knowledge of how to do this. Keep up the great work!

[@joeshmoe7065]

googled rocket fuel injectors, so cool Garcia. We got to get you some more views!

[@felixnica762]

THIS IS AWESOME !!!

awesome videos Charlie! Keep it up :D

[@Felipx2812]

Hey! Very nice to see the progress that you have made, Congrats!!! May you explain a little bit better the capilar tube and the capacitor thing ?? Do you know any article that approaches this information / or any source where i can learn a bit more? Thank you very much for the video 👍👍

[@PauloDutra]

Nice !

[@jurajkolesar1894]

Greetings, I have been wondering, what are those fittings that are connected at the keg throat. I have never seen anything like that. It looks very cool.

[@arielhiramgomezlopez1272]

Hi charlie, super itneresting video. I was wondering what program are you using for the flow diagram you show in 4:55, it would nice know that. Very nice series btw, waiting for the next videos!

[@PeterKocic]

FINALLY!

[@MrSmokayy]

Do you think you will ever do a video series on hybrid engine??

[@nolanlautrette8779]

Interesting video, learned a lot. One question through - how did you install the capacitive fill sensor such that it was electrically isolated from tank while still being able to hold pressure at cryo?

[@AstroCharlie]

I used teflon bushings installed with RTV adhesive

[@TheRealReidMeister]

Hey Charlie, I've been following for a while now and I am actually attempting a liquid engine design in university for an extracurricular group (I'm a junior year mechanical engineering student). So far the most difficult thing from a design standpoint has been the plumbing/valves (especially valves that have to operate at high pressures and handle cryogenic fluids). Do you have any recommendations for textbooks on plumbing (especially plumbing for cryogenic fluids), and also what software are you using to sketch up your plumbing design? In terms of tanks, a roadblock that I've run into that it seems you did too was how to get these tanks manufactured. Still working on that one (and trying to keep the cost down). Thanks for all of the useful information

[@-danR]

People are overthinking this cryogenic-steel-construction nonsense. That stuff is for Elon Musk and the other professionals. Just use plastic, mainly, and overwrap linearly and radially with epoxy and fiberglass. You could even use polypropylene or high-density polyethylene LOX tanks by lightly sandpapering, acid-treating, the surface for epoxy-adhesion. Fiberglass gets _stronger_ at cryogenic temperatures, too. You're going to have fat plumbing, of course, but none this test-stand stuff is going to fly anyway, so what does it matter. And besides, apart from the engine proper, you probably _could_ make a pretty decent liquid fuel amateur rocket with plastic and fiberglass anyway. For more details on rocketry-oriented fiberglass construction, check: apps.dtic.mil/dtic/tr/fulltext/u2/405170.pdf "The Effect of Cryogenic Temperatures on the Mechanical Properties of Reinforced Plastic Laminates." 1963 Finally, would such a system blow up? Of course it would. It ain't rocketry if something don't blow up. Failure isn't an option, it's a necessity.

[@matthewstaton6810]

This dude died and came back to life... just now.

[@AstroCharlie]

I personally prefer to view it as a journey through the underworld and back, but call it what you will.

[@agsystems8220]

Great work as always. Guessing you meant 8mm for the steel, and you are not attaching it to the side of a battleship... :P Anyway, only slight modification I might suggest is switching which fitting goes through the plate, so that if the engine goes RUD there is a steel plate between it and the 1.2 safety factor pressure vessels. Or is that deliberate? This way you can put the steel plate between yourself and both the engine and the tanks, and have it double up as your primary blast shield? Also, are you using helium as your pressurant? I guess it will avoid any possible mixture woes but will probably end up being vastly more expensive than the fuels. An alternative would be have separate pressure tanks for fuel and oxidiser, and use oxygen gas to pressurise the oxidiser and nitrogen for the fuel, (or live dangerously and use oxygen for both, pre-cooling the fuel is suggested if you do this, and not having neighbours. Or ignore any mixture issues and use nitrogen for both. I really don't know if mixture problems would occur). Putting some liquid oxygen/nitrogen in a pressure vessel and then letting it return to ambient temperature (with a regulator, and maybe a little artificial heating for speed). Will need a little more time to set up, but it can actually avoid any fittings that have to be connected under pressure. This can also avoid a large inventory of pressurised gas if you want to do lots of firings without having to resupply, as everything can be easily stored unpressurised.

[@AstroCharlie]

The engine will be on a separate structure, with steel in-between both me and the engine and the tanks. Essentially the engine will attach to a little 2" steel tube box that will sit about 18" below this structure. I have to use helium because I'm using dip tubes now. If I used nitrogen and flowed it up through the LOX there would be a risk of ullege collapse. I'm hoping that I can use nitrogen on my pneumatic leg and on my fuel side, but if I do, I'll just hook a K-bottle up, so there isn't much design work to do.

[@thecros1076]

Hie bro rather than having capacitive lox sensor and its other complexities you can just have them mounted on load cells and then measure weight and get your tank filled volumes.

[@Dead1Eagle6]

Charlie, not sure if you know but imagine you do... cryogenic service valves usually have a stem extension to move the packing material out of the cold area. Not sure from your models if you have that, or if you really have any significant concern with packing damage with this application.

[@AstroCharlie]

I absolutely do not have that, and we'll see how bad of a choice that is after I star breaking valves... I'm only expecting to put a few lifetime cycles on the valves, so hopefully it'll be okay.

[@spaceCowboy924]

Any valves you’re going to have chilled in to cryo temps without a thermal standoff will break within minutes. Would highly recommend looking into this depending on how long it’ll be between filling the lox and firing the engine

[@Graham.556]

Stay safe!

[@putteslaintxtbks5166]

I'm rewatching this and again see this set-up looking good for a test stand, but not a rocket as the tanks are side by side were one should be above the other and one tank should be doubled if fuel to ox is 1:2 ratio. Or is this going to be a really fat rocket and maybe a 1:1 ratio with extra fuel for cooling or ?

[@robertsteinbeiss8478]

If you say cryo, think of Insulation and leave some space on the test stand to wrap it around @Charlie

[@AstroCharlie]

I have .25 inch Zotek foam for insulation. That still leaves .125 in of clearance to the back of the stand

[@subratgupta3773]

Had you considered electric Turbo pump

[@AstroCharlie]

Yes. So many times, yes. I'd love to.... but only when I have more than enough time to actually do normal rockets, which has been hard lately.

[@charadremur333]

@@AstroCharlie well you probably got time now

[@shinjithenegotiator2795]

aye

[@quaternarytetrad4039]

Sort of a looking-ahead question: What do you suppose you would use for an injector plate?

[@AstroCharlie]

See episode 2 and 3. I'm going to use a pintle!

[@quaternarytetrad4039]

@@AstroCharlie oh, cool. I'll check those out!

[@ravener96]

Is the sheet supposed to lie on the ground? Pretty sure its not stiff enough to hold all that stuff up

[@AstroCharlie]

The sheet will have a welded frame backing.

[@modernage5365]

Where can I get the design files to try myself.

[@alexcherry5743]

Hey Charlie, Have you considered using 2L soda bottles wrapped in fiberglass for the fuel tank? This might result in a more flight weight tank. They cost approximately $4 to make each. Air command rockets have tested them to 300psi but didn’t have the equipment to test them above that. Look here: www.aircommandrockets.com/day91.htm to see what I’m talking about. Also is there a reason you aren’t just regulating the pressure over the fuel and oxidizer in their tanks instead of trying to directly deal with a cytogenetic fluid? By varying the pressure in the tanks wouldn’t that adjust the flow rate? With a precisely made injector this would eliminate the need for any low temperature valves. I think you might run into trouble with the valve handling liquid oxygen. Have you considered using dinitrogen tetroxide as an oxidizer? While it’s performance is much lower it is much easier to handle.

[@jheins3]

Not charlie, but my guess is that the system would be near equally as complex regulating pressure upstream as it would downstream (just an added variable of temperature) and you would lose substantial ability to throttle engine as you would have to decrease pressure to slow down engine. Since the tanks are substantially larger than the plumbing hardware, there would be large delays in pressure changes (more volume to regulate). Which brings me to the last problem is that you could see yourself with a pressure inversion, sending fuel and oxygen back into the tanks. So you would still need check valves. Downstream tubing/valves allows more flexibility and also a larger envelope to improve and upgrade design. And its how the big bois do it.

[@lukasdimmler2622]

How exactly does the fuel/oxidizer move into/ out of your capacitative gauge? Are there small holes or slots? I haven't seen them in your design and I am concerned that it might not react fast enough otherwise.

[@AstroCharlie]

In the test article it moves in from the bottom. In the real version I'll need additional testing on the capillary effects to determine the sizing of both the tubes and the metering orifices.

[@lukasdimmler2622]

@@AstroCharlie Thank you for answering. I thought the Teflon bushings might make fluid flow impossible. Wouldn't it be easier to have a tube for the helium gas and a solid wire fixed next to it instead of a tube? Or would that seriously hinder integration?

[@MasterRipper12345]

Wouldn't you save yourself a lot of design and mitigate more risk using electrically actuated valves instead of pnuematics?

[@ThatOneOddGuy]

Welder - MICHEALCHTULU

[@GospodinJean]

Colorado is a more proper place for a rocketeer lol

[@noahhastings6145]

Living in Colorado? Gee, I wONdEr wHo yOu coULd be WorKiNg fOR??? (If you could send my resume to one of their recruiters, I'd appreciate it. I'm an ME looking to get into propulsion. Just picked up Rocket Propulsion Elements. Please let me know if you'd be willing.)