Powerful oxyhydrogen cannon - We have a lift-off!

[markusb]

Spark_generator_circuit_diagram1.JPG (104196Bytes)
Functional_principle_cannon.jpg (59248Bytes)

I have started to build a more powerful oxyhydrogen cannon, something similar like Estes Hydrogen Fuel Rocket:

The igniter of the Estes Hydrogen Fuel Rocket is simply a nichrome wire, but I want to continue to ignite the oxyhydrogen via spark. The spark generator I have used for the mosquito rover was a HV PCB from a bug zapper and it works not very reliable, so I designed a new one with a certain flash over at a spark gap of 1 mm:

The circuit is very similar to the voltage multiplier of my Geiger counter design, but without voltage regulation and with one Villard cascade more, able to produce about 2 kV (see attachment).

How to get perfect graphite electrodes by dismantling an AA alkali battery (No NiCd or Li-Ion battery!):

Keep the manganese dioxide and zinc casing, you can make interesting chemical experiments with it.

The electrolysis is monitoredby a Picaxe 08. If enough gas is generated, a short buzzer sounds and a green LED begin to flash. The ignition than is remote controlled.

Cannon functional principle and design:

Details of the "rocket":

It's not really a rocket, it's a projectile, because it has no own propulsion.

The projectile weights 52.6g.

Due to the large electrode surface, the electrolysis chamber draw 400mA at 7.2V (electrolyte: 6g acetic acid 100%./100 ml water) and produces accordingly a lot of oxygen/hydrogen more than before.

2010.7.15

All boards are assambled now and working fine:

Programming the cannon:

Now I just have to launch the projectile...

2010.7.18 First launch passed

TBC

https://www.youtube.com/watch?v=9PyzRzx7b2E

[amando96]

What are the graphite

What are the graphite electrodes for? spark?

 

I remember some chemical experiment from a while ago that asked for manganese dioxide, but i didn’t know how safe it was to open a battery…

[markusb]

Hi amando,The graphite

Hi amando,

The graphite electrodes are for the electrolysis. If you dismantle a AA alkali battery, there shall be no safety problem. But you better wear gloves.

[telefox]

Are you using a timer to

Are you using a timer to figure out when enough gas has been generated?

[markusb]

Hi TF,Yes, I am using a

Hi TF,

Yes, I am using a Picaxe 08 as a timer. The electrochemical equivalent of oxyhydrogen is 0.6686 l/Ah.I am using a 7.2 V NiCd battery to power the electrolysis. The electrolysis chamber draw 400 mA at 7.2 V (electrolyte: 6g acetic acid 100%./100 ml water), so the cannon would be able to produce around 0.267 l/h with this electrolyte.

You have to press a pushbutton to start the electrolysis. A red LED indicates the electrolysis process. After Δt is reached, a buzzer and a green LED indicate that the cannon is ready to fire. The Picaxe 08 enables then the ignition circuit (RX and HV generator).

[amando96]

Ah, so the graphite won’t

Ah, so the graphite won’t oxidize? i remember doing electrolysis with normal wires, and they got completely oxidized.

[telefox]

Not only is graphite

Not only is graphite resistant to oxidisation, but as an electrode in solution it has a huge effective surface area, so it can deliver a large current for speedy electrolysis.

[markusb]

Yes, right, only a few anode

Yes, right, only a few anode materials are inert during electrolysis, for example graphite (carbon) or platinum. But platinum is sooooo expensive:)

[digi01]

nice building.i like
nice building.i like chemical much more when i was in high school,ohh,that good times…

[arvotron]

Impressive!

I just love any kind of remote detonation!

One q: when the oxyhydrogen is ignited, doesnt it expand in both directions (up and down the tube)? I dont see the tube bursting, so I assume you have somehow sealed the electrolysis chamber tight but managed to bring the electrode wires inside.

And thanks for reminding about graphite electrodes. They would totally help me with one of my previous projects.

[markusb]

Hi ArvotroN,Yes, the bottom

Hi ArvotroN,

Yes, the bottom side of the electrolysis chamber is moulded with epoxy resin.

[BaseOverApex]

It’s an amazing project. I

It’s an amazing project. I realise it’s a bit late, but would you give any consideration to mounting the launcher further away fro teh scooshy wet stuff? (Just in case.)

For heaven’s sake no-one tell Fritz we’re using explosives to propel robots.

[fritsl]