Little_Ghost_again
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Anyway to produce alot of oxygen quickly for a motor?
Hi
I mentioned in another post almost tongue in cheek about a competition in my science class at the end of next term.
I dont go into the actual building much but I still do the school work mostly from home, in my science class (general science) they have been doing
about thrust and acceleration, I get lesson plans way ahead of time so my tutor can prepare stuff in advance and lessons for me can be arranged around
my treatment.
I notice that at the end of next term there will be a competition held in the hall for small CO2 powered cars (it dosnt actually say CO2 has to be
used, it's more of a suggestion), the idea being that after learning about thrust and acceleration we build a small viechle and race over a short
distance (about 30-40m).
This got me wondering..................Is it possible to build a hybrid rocket from acrylic for this? The main problem is generating enough oxygen to
power the motor for around 8-12 seconds.
How do I build a oxygen generator safely (ish), ok one way valve in the feed line is obvious, I can build and use a remote control unit so using wire
wool for the fuse to ignite the motor isnt an issue. I can also use servo's etc for valves easy enough, my problem is what is the best method apart
from liquid oxygen to produce oxygen is a large enough amount to power this for upto 12 seconds or so?
I know someone is going to use a small CO2 cylinder for drinks making machine to power theirs, but they dont have the electronics know how to do the
controller (they asked me).
I cant resist the idea of a small acrylic cylinder suddenly coming to life and powering my car off down the hall. Anyone got some generator ideas I
can try out at home to make oxygen and power a small hybrid motor?
I am making the car from Balsa wood mainly.
Dont ask me, I only know enough to be dangerous
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HgDinis25
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If I understood correctly, you want fast generation of Oxygen to actualy make the trhust instead of the combustion of Oxygen, right?
The best method is always using Hydrogen Peroxide. 35% works great. Just put it in a container. Whenever you need thrust you open a valve that allow
the H2O2 to fall or slip into a catalyst (manganese dioxide for instance) and there you go, trhuuuuuuuuuuuuuuuuuuuust.
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Little_Ghost_again
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Quote: Originally posted by HgDinis25  | If I understood correctly, you want fast generation of Oxygen to actualy make the trhust instead of the combustion of Oxygen, right?
The best method is always using Hydrogen Peroxide. 35% works great. Just put it in a container. Whenever you need thrust you open a valve that allow
the H2O2 to fall or slip into a catalyst (manganese dioxide for instance) and there you go, trhuuuuuuuuuuuuuuuuuuuust. |
That dosnt sound too bad  , it also means I can use a one way valve to the
catalyst container, I am going to use the oxygen to burn the acrylic tube like in a hybrid rocket.
I will drill a hole through a solid acrylic cylinder and feed the oxygen into one end and light the other, so the oxygen will be used for combustion
of the acrylic. I have a load cell I can use for testing of the exhaust shape, my problem is the short distance of the track. I know over longer
distance I could thrash CO2, but short distance is harder because I will need a fair bit of oxygen quickly.
Apparently in class they have done pop bottle type experiments with CO2 and so I think most will go this way, but the sheet I have dosnt say I cant
use other materials or combustion. The way you explain it above makes me think I should be able to control it fairly well from a safety perspective,
the hybrid motors I have looked at (you tube) all seem to go out quick enough when you stop the oxygen.
Dont ask me, I only know enough to be dangerous
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Metacelsus
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How are you going to start the motor?
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TheAlchemistPirate
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Idea for how to use H202 and a catalyst for a ground vehicle's rocket:
A piston and cylinder is built so that the piston rod is a rack and pinion with an electric motor pushing it forward. A removable one way valve that
releases at a certain pressure is placed on the other end, and unscrewed to pour the H202 into it. When the electric motor is turned on, the piston
should move forward and cause the valve to release and spray a jet of H202. A cylindrical block of a catalyst(manganese dioxide?) is drilled through
and placed between the acrylic cylinder and the piston's valve. Nichrome wire is placed into the rocket's nozzle just before the acrylic block, and
electronically triggered to glow before the piston shoots the H202 through the catalyst block's hole, causing hot oxygen to shoot down the channel and
start the rocket.I hope this makes sense.
A low power solid fuel rocket engine would be much easier though .
What school do you go to that lets you actually build things like rocket cars? I have to figure this stuff out on my own.
"Is this even science anymore?!"
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Bert
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If they would allow you to use ANY type of a chemical combustion or decomposition powered rocket- Be it a monopropellant, hybrid or solid fueled
indoors in your school, I will be quite surprised. Rocket engine design programs conducted by amateurs all have one unifying feature: frequent CATOs
during the learning phase! (CATastrOphic failures...). Best clarify that before doing too much design work?
If it's got to be powered by puncturing a CO2 cylinder, best bet will be a proper expansion chamber to make maximum use of the expanding gas, and a
method to transfer heat into the propellant to keep vaporizing it briskly, rather than losing performance as it chills.
If a small hybrid rocket, how about nitrous oxide from a whipped cream cylinder as oxidizer, with a cardboard tube as fuel grain.
Rapopart’s Rules for critical commentary:
1. Attempt to re-express your target’s position so clearly, vividly and fairly that your target says: “Thanks, I wish I’d thought of putting it
that way.”
2. List any points of agreement (especially if they are not matters of general or widespread agreement).
3. Mention anything you have learned from your target.
4. Only then are you permitted to say so much as a word of rebuttal or criticism.
Anatol Rapoport was a Russian-born American mathematical psychologist (1911-2007).
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Little_Ghost_again
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I dont know if they do let us use rocket propelled cars, I know that they used citric acid and calcium bicarb in a pop bottle for the demo, and I am
pretty sure they assume most people will copy this for the race.
But we are given a sheet that details what we can and cant do, it says we cant use electric motors to power it, we cant push it at the start line etc
etc.
They assume most of us are pretty stupid and it would never occur to them that someone would use a solid rocket for fuel or a hybrid, also I rarely go
into the school. They dont have any idea I now have an interest in chemistry, but the rules say nothing about using pyro or anything else so by the
time they have any idea what powers my car it will be off down the race track.
To light it I am thinking iron wool soaked in a little WD40 and a 9v battery, the guy with the small co2 cylinder isnt puncturing it, he has taken the
nozel etc out the drinks maker and I will sort him out a servo on a timer that will turn the valve on for him (3 seconds then on).
I am likely to get disqualified for sure (a bit unfair) but its worth it to see the look on there face. I have done a few tests and while not great
(the H2O2 was only 3%) it shows promise . I have got dad to order 35% H2O2 for
me.
As I am using a micro for part the control system I might add a load cell strip and put that around the reaction container (a chemical container) when
its full and starts to deform outward I will get the micro the release the valve via a servo motor turning the valve (stainless steal use for aquarium
air lines).
Its a shame they are not using the corridor (much longer) and just timing the runs one by one.
I do have the advantage that mine is being built outside the school (everyone else is doing most of it in class), so its unlikely they will know what
I have built until I power it up and by then its too late.
We are always being told ALL WE NEED TO KNOW IS ON THE WORK SHEET SO READ IT. They hate answering questions so I figure I have done as asked and read
the sheet several times, it does suggest CO2 is used via citric acid and bicarb, but it dosnt say it must be used, infact it suggests we "Find other
chemicals to produce thrust" That to me is the green light!
I cant get hold of nitrous oxide easily and in a form I can use, thats why I went with H2O2.
Its a bit of a protest as well, I recently got my biology mock exam back and I got marked down on a few answers unfairly, for example the one that
pissed me off was name the smallest type of living organism, now I know they wanted virus, but in my answer I argued that seeing the first question on
the paper was to name the missing parameters that define life, then using there parameters for life it was bacteria. I explained that had the
parameters been different I would have used Virus or even prion but these dont fit the living parameters in the first question so virus and prion are
excluded and the answer has to be bacteria.
I got 0 marks for it!!!!
There were several other questions I got the same treatment! so I got a low grade in biology  even though my answers were all correct!
Name the organism responsible for fermentation in wine! I named 3 (non were yeast) and explained that seeing as they didnt name the fermentation
product then I was assuming they wanted any of the organisms responsible for fermentation products in wine and not just Ethanol, I also pointed out
that clostridium also ferments to ethanol in wine. Again I got 0 points
Dont ask me, I only know enough to be dangerous
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Bert
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OK- have a look at this, too:
http://www.aeroconsystems.com/motors/Screamer_folder/Screame...
If you can email me that work sheet, I would like to see exact parameters.
If your school has an online posting of their safety guidelines, it may be possible to tailor your entry to pass them...
| Quote: |
To light it I am thinking iron wool soaked in a little WD40 and a 9v battery, the guy with the small co2 cylinder isnt puncturing it, he has taken the
nozel etc out the drinks maker and I will sort him out a servo on a timer that will turn the valve on for him (3 seconds then on).
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I would advise not using an onboard timing circuit with no remote "panic button" in case you need to abort your launch.
A remote control requiring TWO POSITIVE ACTIONS TO FIRE is a more professional (and likely safer!) choice.
[Edited on 22-12-2014 by Bert]
Rapopart’s Rules for critical commentary:
1. Attempt to re-express your target’s position so clearly, vividly and fairly that your target says: “Thanks, I wish I’d thought of putting it
that way.”
2. List any points of agreement (especially if they are not matters of general or widespread agreement).
3. Mention anything you have learned from your target.
4. Only then are you permitted to say so much as a word of rebuttal or criticism.
Anatol Rapoport was a Russian-born American mathematical psychologist (1911-2007).
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Little_Ghost_again
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That is really cool! but I dont think the whipped cream thing is available in the UK, I can get large cylinders of it but nothing that small, I dont
know why but maybe nitrous oxide is controlled here?? I would love to be wrong.
The graphite nozell has given me some ideas , maybe I can find a way to fill a
small CO2 cylinder with Nitrous from a larger cylinder. Need to experiment to see what kind of burn time I need, short but fast is probably best.
GENERAL NOTE
I havnt ignored Berts questions, but personal details etc I only really answer in u2u's so I did answer Bert just not in the thread . I didnt want you to think i was rude and ignored people
[Edited on 22-12-2014 by Little_Ghost_again]
[Edited on 22-12-2014 by Little_Ghost_again]
I checked and nothing online (public anyway) about safety guides, I tried to log into moodle at the school but it seems over holidays there is no
access as I cant log in!!
I will post the sheet when school starts again as I dont have a scanner but they have a electronic version of all work sheets on moodle (thats how I
get them).
The safety stuff is very very handy, I am thinking long and hard about the safety.
I would have more confidence in this if they used the bloody corridor! Its much much longer than the hall so by the time I reached the end little
energy if any left, the hall is another matter, short distance and HARD wall at the end! So quick hard burn, the controls I havnt really though much
about.
This isnt an oversight its simply that I have alot of electronics experience so my confidence of building a complex safety circuit means its what I
will look at last (sort of).
At the moment I am undecided if this is practical seeing as the wall is only 5-10 meters from the finish line, I dont mind destruction of the car on
impact with the wall as long as the H2O2 is all used up and the motor is out.
But on the other hand..............................
I should be able to do this, if I test and test and build in enough safety then it should be ok......................................................
Yeah ok I need a plan B
I will be back with plan B
[Edited on 22-12-2014 by Little_Ghost_again]
Dont ask me, I only know enough to be dangerous
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