Building air pressure scooter?

[boot82050]

Are there people who have build a underwater scooter with air pressure?
I want to build a underwater scooter witch is propelled bij a 15 liter air tank with 300 bar

Has someone got building idea's ie for the transmission to the propellar?

Greetings,
J Bodewitz

[mddolson]

I don't recall what the engine type was called in the torpedo community, but I read about them a long time ago in pop mechanics, where they were called a wobble plate
engine.

There are a number of parallel cylinder and a tilted elliptical plate with a track for the rod ends. The rod run around the track and thus move in and out of the cylinders. There's some rotation in there somewhere, but I don't recall the exact way it worked. There are valves in the head to let the high pressure gas in to drove the pistons back, and to let the gas out when the pistons move back into the cylinder.

Mike D

[Scuba_Vixen]

That would have been the long skinny ones that looked about like a starter. 3 Double ended pistons (6 altogether) with a warble plate in the middle. I wonder if they'll work bass ackwards?

[boot82050]

i thought the easyest way was to use a wheel with blades on it
to propel the propellor.
but i dont'n t have experience with this concept.

j bodewitz

[Braunbehrens]

First thing you should do is figure out if there is enough power in the tank to make it worthwhile.

I've been thinking about it, and I don't think there is.

Here is my reasoning:

To propel a diver, the valve would most likely need to be wide open. This means that the tank would empty pretty fast.

For the actual calculation you'd probably need to figure out how much energy is required to prople the diver forward. Then figure out how much energy is present in the tank. You'll probably loose at least 30% of the energy, so that should be factored in.

IF, and it's a big IF, it's possible to make such a contraption, then it would be worthwhile to see if you can collect the gas at the exhaust to use for breathing. For example, instead of dropping the gas to ambient, you could drop it to an intermediate pressure of 100psi above ambient, then use a second stage.

Cool project in any case, I'll be curious to see if it goes anywhere.

[boot82050]

thanks for you reply,
I think there is a lot of energy stored in the tank becouse it can go through a brick wall if the valve is hammered of. (some found out by accident).
I thought some people would have already tried this at home.
I am curious to, so I think I am goint to build a prototype.
Greetings,

Justin bodewitz

[Braunbehrens]

boot82050 once bubbled...
thanks for you reply,
I think there is a lot of energy stored in the tank becouse it can go through a brick wall if the valve is hammered of. (some found out by accident).
I thought some people would have already tried this at home.
I am curious to, so I think I am goint to build a prototype.
Greetings,

Justin bodewitz

Yes, but that is all the energy released at once, and on the surface.

You could build a setup where the air escaping from the tank valve pushes down on a scale. This would tell you how much force the tank is putting out with the tank valve open.

I'm sure there is a mathematical formula as well, but I don't know what it is.

[Braunbehrens]

I did a little more research on the subject.

It looks like the energy from a scuba tank is roughly equivalent to a 24 volt battery producing 15 amps for one hour.

This would probably be enough to drive a scooter.

[Munin]

I had an engineer friend who worked it out once. An 80 gave only a few minutes of time, something like 5-10 minutes. It must depend on the drive train design, though, and I don't know what he used for that.

[kavka]

Few years ago someone was driving a boat on such engine.Motor boats are in Bled lake forbidden so he was using compresed air. As I know 15l tank was enaugh for 1h. I'll ask for plans.

[rustman]

Sounds like a cool project if it is feasible.

You might need some way to adjust the volume of the unit so its buoyancy doesn't change as you exhaust the air.

How about a propane powered unit? You could use the cylinder for combustion air and a small camping style propane cylinder (or 2?) as fuel. This might add the extra zing necessary to make it work.

(I think it is time to break out my chemistry book...)


Tom

[PhotoTJ]

I read somewhere that there is 1.3 million ft. lbs. of energy in a full 80, I would think someone could figure out a way to harness that.

[Jaap]

Yes I have seen pictures of old penumatic UW-scooters from around 1960. They looked like a tow behind scooter with a twinset on a frame connected to a simple propeller device similar to a penuamtic grinding machine except with a propeller instead of the grinding disk.

Here is a link to on version of the calculation of the energy stored in a tank: http://www.combro.co.uk/nigelh/diver/tank.html

I derived a similar calcuation calcualtion a couple of years ago when I also thought of buliding a penumatic scooter but I figured I would only really get a fraction of the power in the above calcualtion so I decided it would was easier to buy a used scooter and to tinker on with other scubaprojects...

The problem with an air powered scooter is that you would have to have a complicated machine if you want to used the explanded air for breathing, you would also loose avalible power with depth due to the increase in ambient preassure. You would also probably end up with a fairly low efficiency in turning the pressure into effective propulsion. I would say you would ned about 300 Watts of power to the prop (J/s) to get anywere and then you would problably have to spend at least as much energy on losses getting that power to the prop.

If you just want a cheap scooter I would recomend buying a used one or buildning an electric scooter. But if you take it as a challenge to have a air powered scooter, god luck! Please let us know if you get it working.

[boot82050]

Thanks for all reactions,

**Few years ago someone was driving a boat on such engine.Motor boats are in Bled lake forbidden so he was using compresed air. As I know 15l tank was enaugh for 1h. I'll ask for plans.**

I would veary mutch like to see these plans or hear about the concept he used.

Greetings,
j boidewitz

ps I dont kwow about the propane plan, if it is possible i like to stick to just air becouse i will just have to fill a tank of air.

[patymeboy]

I would like to know if it is posible to build a scooter using ion power

[patymeboy]

no realy are there plans for electric home built scooters anywere

[phunk]

If by 'ion power' you mean the ions in a battery, then yes.

If you're thinking of something along the lines of one of those ionic air purifiers that create a breeze with no moving parts, it'll never work with water.

[miketsp]

First thing you should do is figure out if there is enough power in the tank to make it worthwhile.

I've been thinking about it, and I don't think there is.

Here is my reasoning:

To propel a diver, the valve would most likely need to be wide open. This means that the tank would empty pretty fast.
..snip..



You're thinking purely of jet propulsion.
To use a cylinder efficiently you should think in terms of a triple expansion steam engine.
There's a nice animation about half way down this page.
http://en.wikipedia.org/wiki/Steam_engine

It should be possible get quite a high overall efficiency if you drive a large slow turning prop.

I've seen some nice models for steam that could easily be adapted to operate off a regulator IP outlet.

PS. Just been thinking about it and the real key to get efficiency would be a good variable pitch prop to ensure a more or less constant rotational speed as forward speed increases.

[underboats]

I use pneumatic tools frequently underwater for work and at times I have to run them with my tanks. They don't last long. For example, when drilling with a 1/2 drive drill (which would likely turn a propeller with enough thrust to push a person) I can only drill for about 5-10 minutes constant on a full 80cf tank. That's about it. Thought this may help. Chuck

[Where's_Wally]

I'm not sure if this device would be adaptable to underwater use...
I saw a short program on the Australian designed Di Pietro Rotary Air Engine on TV some time ago.
This design of air motor offers very high torque and low internal friction losses for outstanding efficiency.
A quick google search gave me this site - http://www.engineair.com.au/index.htm

Cheers!

[SteveC]

Probably for most people electricity power would be easer to come by than tank air. It's very easy to charge a battery, but expensive to fill a tank.

[mohave_steve]

Take a look at:

FergusonEngineering.com - Micro Motor products (http://fergusonengineering.com/MircoMotor_products.html)

They have air motors that may work for this application.

[moneysavr]

As said the Air tool is the way to go,they can be purchased by the volume of air used per min and power,and run off the low pressure line of your reg,

you will get about 10-15 min of diver pull from a AL 80-wish I had a pick it strapped to the tank and fan-propeller in center behind regulator valve air tool chuck holds fan propeller shaft,

[engdiver]

Another possible link. Various air motors.

ACTUATORS AND AIR MOTORS (http://www.parker.com/EAD/displayCatalog.asp?menu_parkerid=77&menu_gid=37&menu_divid=327&catid=138806&catdesc=P1V-P,%20RADIAL%20PISTON%20AIR%20MOTORS&subcatid=1078850&viewtype=1&sMode=Details)

[miketsp]

Another possible link. Various air motors.

ACTUATORS AND AIR MOTORS (http://www.parker.com/EAD/displayCatalog.asp?menu_parkerid=77&menu_gid=37&menu_divid=327&catid=138806&catdesc=P1V-P,%20RADIAL%20PISTON%20AIR%20MOTORS&subcatid=1078850&viewtype=1&sMode=Details)

Nice.
You'd just have to ensure that no water gets in. Put a non-return valve on the air outlet and ensure that there is a very slow bleed of air from the throttle regulator even in the "off" position to keep the motor always pressurized above ambient.

Also to avoid contaminating the environment with the air/oil mist required you can now get environmentally friendly 2 stroke oils that dissolve in water for nautical use. So you should use this type of oil in the lubricator.

[DA Aquamaster]

When I was younger I used to design and build free flight aircraft using CO2 powered motors. They are basically a single cylinder expansion motor with a piston and rod that turns a rotary crankshaft. The advantage to this design as compared to a impeller or turbine design is that it is much more efficient with virtually no blowby.

A motor like that would work equally well with air but CO2 offers the advantage of a consistent working pressure and storage of the "gas" as a liquid under pressure offering much more gas volume and a longer run time from a given cylinder size.

[meesier42]

what you need is one of these motors. Angel Lab's MYT engine (http://www.angellabsllc.com/resourse.html)

based on air motoring it was tested to produce 800ftlbs of torque on 150psi air (http://www.greencarcongress.com/2006/04/new_toroidal_in.html). Granted the volume that you would use is way more than you have, but you don't need 800ftlbs of torque either.

[24940]

I've run the numbers using various modern, high efficiency drives and it isn't practical. The volume just isn't sufficient to provide much more than 10 minutes of trigger time with an AL80. There are also back pressure issues that would need to be resolved.

Great concept, though.