Questions: tiny RCS h2o2 nozzles for zero-g operation in atmosphere and vacuum

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sirus20x6

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I'm interested in building a tiny rocket drone for a contest. It will almost certainly never actually be used, but it should be functional. my basic idea is an aluminum sphere with an hd camera and a set of tiny RCS hydrogen peroxide nozzles built in. The brains would be an arm microcontroller and the details of that really aren't important. what I'd really like feedback here is about how to meter out such tiny amounts of thrust and what materials I would have to use. my guess is that thermal requirements aren't going to be an issue since it in theory wont ever have to push against gravity. my first thought would be to atomize a small amount of h2o2 with a piezoelectric ultrasonic transducer and then have the mist pass through one of these guys https://www.peroxidepropulsion.com/catalysts.php

All together i'm guessing the weight would be 5-10 pounds.

what are your thoughts? is temperature an issue or do you think i can get away with an aluminum nozzle?

All serious feedback appreciated.
 
sirus20x6 said:
I'm interested in building a tiny rocket drone for a contest. It will almost certainly never actually be used, but it should be functional. my basic idea is an aluminum sphere with an hd camera and a set of tiny RCS hydrogen peroxide nozzles built in. The brains would be an arm microcontroller and the details of that really aren't important. what I'd really like feedback here is about how to meter out such tiny amounts of thrust and what materials I would have to use. my guess is that thermal requirements aren't going to be an issue since it in theory wont ever have to push against gravity. my first thought would be to atomize a small amount of h2o2 with a piezoelectric ultrasonic transducer and then have the mist pass through one of these guys https://www.peroxidepropulsion.com/catalysts.php

All together i'm guessing the weight would be 5-10 pounds.

what are your thoughts? is temperature an issue or do you think i can get away with an aluminum nozzle?

All serious feedback appreciated.
Click to expand...

Here you probably wouldn't get as much helpful feedback as you need. You should probably join the amateur rocketry mailing list Arocket and ask there: there are several people who have experience building peroxide rockets there who would be better qualified to offer you advice.
 
Which do you have more of, reaction mass or electric power? How much thrust do you need, and how much total impulse? If the available reaction mass x ISP < total impulse required, you might make it work. If not, you need greater ISP. If it needs to be too great, I'd look at some form of ion drive. I don't know offhand if you need a temperature control on the H2O, or need to modify it to extend the working temperature range, but I do know it may not be ideal for long term storage? NOFB is another option which would behave similarly but with higher ISP.

I've perhaps exhausted my knowledge on the subject there. I'm NOT an expert in reaction control systems. But I suspect there is a lot of research plus sections in textbooks on the subject.

Gerald
 
G_T said:
Which do you have more of, reaction mass or electric power? How much thrust do you need, and how much total impulse?
Click to expand...
as for how much thrust i'm thinking that to move such a small object i would need next to nothing for each burst but I don't know how to equate battery power and reaction mass on an equal scale and I have no intuitive idea of how much isp would be necessary in zero g. I'm going to try to find some simulation software so i can get an idea of how much thrust it takes to move an object of the approximate mass i'm looking at and then make a decision about the ratio of battery mass to reaction mass as well as absolute volume and mass based on that.


Does anyone know of good software that I can model that in? I have access to 3d studio max but it's been about a decade since i've used it. I think I might be able to use something like that.

Also the reason I want to go with h2o2 is if the theory of this device is to operate inside and out of something like the ISS then having the output be o2 and h2o is a big plus. I had considered ion but I was worried about it taking too long to accelerate and I also worry that the extremely high voltages might be dangerous to people and equipment in close quarters like a space station. also the byproduct of that would be lots of unhealthy O3.
 
CarVac said:
Here you probably wouldn't get as much helpful feedback as you need. You should probably join the amateur rocketry mailing list Arocket and ask there: there are several people who have experience building peroxide rockets there who would be better qualified to offer you advice.
Click to expand...

thanks, signed up!
 
I was thinking of electrical power being sourced primarily from solar cells. The power may be low, but the available energy is bounded by time. So if the probe is in no hurry... Also no reason to produce O3; that would be a function of the choice of reaction mass. Proximity to other stuff though is a consideration.

Another option is electric currents used to navigate against available magnetic fields. Again, if one is in no hurry and is somewhere where such fields are available (near earth), it may be a very experimental option for a light probe. Near other objects, you'd likely have to sample the field vector, compute the electrical current vector desired, briefly apply, determine the results, rinse and repeat. But no reaction mass is required.

Gerald
 
sirus20x6 said:
I'm interested in building a tiny rocket drone for a contest. It will almost certainly never actually be used, but it should be functional. my basic idea is an aluminum sphere with an hd camera and a set of tiny RCS hydrogen peroxide nozzles built in. The brains would be an arm microcontroller and the details of that really aren't important. what I'd really like feedback here is about how to meter out such tiny amounts of thrust and what materials I would have to use. my guess is that thermal requirements aren't going to be an issue since it in theory wont ever have to push against gravity. my first thought would be to atomize a small amount of h2o2 with a piezoelectric ultrasonic transducer and then have the mist pass through one of these guys https://www.peroxidepropulsion.com/catalysts.php

All together i'm guessing the weight would be 5-10 pounds.

what are your thoughts? is temperature an issue or do you think i can get away with an aluminum nozzle?

All serious feedback appreciated.
Click to expand...
No. That's not how it done.

The materials used in the tankage and valving are critically important to prevent the peroxide from decomposing or even exploding when filling and operating the motor. The catalyst bed will actually melt if not properly designed. You might want to look at the old Armadillo Aerospace log on their attempts to make a peroxide thruster. It actually a good lesson on what not to do.

You might want to start by downloading the peroxide handbook which provides real physical data on peroxide. You also might want to download the numerous DTIC reports on peroxide motors.

Making a peroxide motor is nontrivial, so I'm not going to go into details here on were to get the information on-line in the public propulsion forum. If you are high power certified, request for access to the research forum and we can discuss it in detail.

Bob
 
Is a high pressure nitrogen bottle out of the question? Little spurts of nice, cold, non-reactive nitrogen, ahhh so peaceful.

Honestly though, you don't need very much to turn a small vehicle, and even so, you can just rotate slowly if need be. Letting a small jet of gas out from 2000 PSI-vacuum will generate a lot of rotational energy, if pointed in the right direction.
 
It might not be as space efficient, but rotations can be done with small pump and tube of liquid in a ring. Three sets, three planes, three axis of rotation. Pump to rotate. Continue pumping, continue rotating. Stop pumping, stop rotating. No mass loss involved, just a little electrical power.

That's only for rotational control, not other motion.

Gerald
 
bobkrech said:
No. That's not how it done.

The materials used in the tankage and valving are critically important to prevent the peroxide from decomposing or even exploding when filling and operating the motor. The catalyst bed will actually melt if not properly designed. You might want to look at the old Armadillo Aerospace log on their attempts to make a peroxide thruster. It actually a good lesson on what not to do.

You might want to start by downloading the peroxide handbook which provides real physical data on peroxide. You also might want to download the numerous DTIC reports on peroxide motors.

Making a peroxide motor is nontrivial, so I'm not going to go into details here on were to get the information on-line in the public propulsion forum. If you are high power certified, request for access to the research forum and we can discuss it in detail.

Bob
Click to expand...

I had found this for material compatibility https://www.ozoneservices.com/articles/004.htm also on ebay a guy is selling a couple 10lbs thrust and one 50lbs thrust h2o2 rocket and he uses 347 and 302 stainless steel.

https://www.ebay.com/itm/RCS-ROCKET...60?pt=Educational_Toys_US&hash=item3cdbaf5394

https://www.ebay.com/itm/ROCKET-ENG...98?pt=Educational_Toys_US&hash=item3ce0244fea

these are of course way too big for what I'm thinking. thanks for the heads up on armadillo. carmack is sorta a hero of mine so looking into their work would be fun.

I also have no certifications. my primary field is programming and circuit design
 
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G_T said:
It might not be as space efficient, but rotations can be done with small pump and tube of liquid in a ring. Three sets, three planes, three axis of rotation. Pump to rotate. Continue pumping, continue rotating. Stop pumping, stop rotating. No mass loss involved, just a little electrical power.

That's only for rotational control, not other motion.

Gerald
Click to expand...

I was considering using gyroscopes for rotation but I hadnt really decided.
 
Gyroscopes need to be kept spinning so you'll have some current drain from that. The bearings will have to have tolerance for a fair bit of temperature cycling unless you control temperature. Again, I'm NOT an expert at this, but these are just some design considerations that come to mind.
 
sirus20x6 said:
I had found this for material compatibility https://www.ozoneservices.com/articles/004.htm also on ebay a guy is selling a couple 10lbs thrust and one 50lbs thrust h2o2 rocket and he uses 347 and 302 stainless steel.

https://www.ebay.com/itm/RCS-ROCKET...60?pt=Educational_Toys_US&hash=item3cdbaf5394

https://www.ebay.com/itm/ROCKET-ENG...98?pt=Educational_Toys_US&hash=item3ce0244fea .....
Click to expand...
The items on ebay are the shell of the motor only. The important and expensive stuff is missing. You need a catalyst bed (not included), a fast acting liquid hydrogen peroxide compatible valve (not included), a hydrogen peroxide tank (not included), an inert gas pressurization regulator (not included), plumbing (not included), and a source of rocket propellant grade hydrogen peroxide (not included).

Bob
 
Hydrogen peroxide by itself is so dangerous, that I think there is no way that it would ever be allowed inside of ISS. And probably not even inside of a cargo ship to get it to ISS to begin with.

But let's say it was allowed. You assume that the exhaust being nothing but O2 and H2O would be a good thing. But not inside of the ISS or most manned vessels. The H2O means excess water vapor that can get inside of electronics to cause shorts. Or "just" become a potential source of mold.

I am also not sure how well the idea of uncontrolled O2 getting into the atmosphere would go over. In theory, yes, it simply mixes into all the other air onboard. But if there was a freestanding pocket of concentrated O2, that could be dangerous.

Edit - I left out one thing. Since it does "ignite", with combustion to produce the thrust, no way in h*** would that be allowed inside a manned spacecraft. Almost like having a little robot inside that randomly strikes a match at random moments from random ports of the robot's body. NFW.

I really think you'd be better off with electrically controlled mechanical devices, Such as momentum wheels that could rotate the device in 3 axes. The Hubble Telescope does it, not just for efficiency but due to not contaminating itself (especially the mirror and optics) with thruster exhaust.

Inside of the ISS, you could make it "move" by using tiny propellers, more like the tiny electric ducted fans that model planes use, but probably smaller and a heck a a lot less noisy (for crew reasons).

And actually most of this would be reinventing the wheel of some "droids" NASA tested out a few years ago. Here is a link to one:

https://science1.nasa.gov/science-news/science-at-nasa/2006/01jun_spheres/

spheres_slide.jpg


Well, I thought one they tested long ago had little fans. But it actually uses CO2 to power very small thrusters (which is not dangerous as long as the Life Support system works like it should, and they have a spare Lithium canister or two on board to account for it). No combustion, safe (if not very efficient) way to get thruster control. Even Mercury and Gemini used "Cold Gas" thrusters for attitude control, and many satellites still do (some may use cold gas more for vernier thrusters to tweak a critical orbit than attitude control).

Back to the SPHERE droid tests, they could have been "flown" outside on an EVA. Do not know if they did.

Here's more info, they flew three on ISS:
https://ti.arc.nasa.gov/blog/irg/?cat=6&paged=2

173545main_spheres_hi.jpg


- George Gassaway
 
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bobkrech said:
The items on ebay are the shell of the motor only. The important and expensive stuff is missing. You need a catalyst bed (not included), a fast acting liquid hydrogen peroxide compatible valve (not included), a hydrogen peroxide tank (not included), an inert gas pressurization regulator (not included), plumbing (not included), and a source of rocket propellant grade hydrogen peroxide (not included).

Bob
Click to expand...
I understand that. I do have a cheap machinist that I use and a company that specializes with stainless steel with a huge cnc machine that I did a favor for that I would turn to for some of the parts.
 
georgegassaway said:
Hydrogen peroxide by itself is so dangerous, that I think there is no way that it would ever be allowed inside of ISS. And probably not even inside of a cargo ship to get it to ISS to begin with.

But let's say it was allowed. You assume that the exhaust being nothing but O2 and H2O would be a good thing. But not inside of the ISS or most manned vessels. The H2O means excess water vapor that can get inside of electronics to cause shorts. Or "just" become a potential source of mold.

I am also not sure how well the idea of uncontrolled O2 getting into the atmosphere would go over. In theory, yes, it simply mixes into all the other air onboard. But if there was a freestanding pocket of concentrated O2, that could be dangerous.

Edit - I left out one thing. Since it does "ignite", with combustion to produce the thrust, no way in h*** would that be allowed inside a manned spacecraft. Almost like having a little robot inside that randomly strikes a match at random moments from random ports of the robot's body. NFW.

I really think you'd be better off with electrically controlled mechanical devices, Such as momentum wheels that could rotate the device in 3 axes. The Hubble Telescope does it, not just for efficiency but due to not contaminating itself (especially the mirror and optics) with thruster exhaust.

Inside of the ISS, you could make it "move" by using tiny propellers, more like the tiny electric ducted fans that model planes use, but probably smaller and a heck a a lot less noisy (for crew reasons).

And actually most of this would be reinventing the wheel of some "droids" NASA tested out a few years ago. Here is a link to one:

https://science1.nasa.gov/science-news/science-at-nasa/2006/01jun_spheres/

spheres_slide.jpg


Well, I thought one they tested long ago had little fans. But it actually uses CO2 to power very small thrusters (which is not dangerous as long as the Life Support system works like it should, and they have a spare Lithium canister or two on board to account for it). No combustion, safe (if not very efficient) way to get thruster control. Even Mercury and Gemini used "Cold Gas" thrusters for attitude control, and many satellites still do (some may use cold gas more for vernier thrusters to tweak a critical orbit than attitude control).

Back to the SPHERE droid tests, they could have been "flown" outside on an EVA. Do not know if they did.

Here's more info, they flew three on ISS:
https://ti.arc.nasa.gov/blog/irg/?cat=6&paged=2

173545main_spheres_hi.jpg


- George Gassaway
Click to expand...

well darn it does look like it's been done. I would have tried to turn to o2 tank next after h2o2 but it seems they've done it with co2. well this is what puts the nail in the coffin. thanks
 
Correct, because you don't need it to actually chemically react. Something that small can use cold gas jets to move around just fine.
 
Cold gas thrusters are used all the time on satellites.

There is little reason to used peroxide thruster today as hydrazine based monopropellants have a much higher specific impulse and have a 20+ year lifetime. When high thrust and higher Isp is require, the hydrazine are used in bipropellant motors with N2O4 as the oxidizer. Both propellants are toxic so they are not contained in the manned compartment of spacecraft.

The Soyuz does use peroxide thrusters for maneuvering. Peroxide decomposes on storage and that the reason for the 6 month (now 12 month lifetime limit for the Soyuz as the ISS lifeboat. (Refrigerated tankage increased the storage from 6 to 12 months.)

Bob
 

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