Login    Register
User Information
Username:
Password:
We are a free and open
community, all are welcome.
Click here to Register
Sponsored
Who is online

In total there are 36 users online :: 4 registered, 0 hidden and 32 guests


Most users ever online was 218 on Wed Dec 07, 2016 6:58 pm

Registered users: Bing [Bot], Google [Bot], MSNbot Media, Yahoo [Bot] based on users active over the past 5 minutes

The Team
Administrators
Global Moderators
global_moderators.png CS

Liquid fueled hybrid

Post questions and info about hybrid (compressed gas with fuel) powered cannons here. This includes discussion about fuels, ratios, ignition systems, build types, safety, and anything else relevant.
Sponsored 
  • Author
    Message

Unread postAuthor: SPG » Sat May 16, 2009 10:33 am

How big a hybrid are you thinking of building? Or to be more precise how much meths are you going to need to put into your chamber? I've got a vague idea involving spool valves, but if it's a small amount then a 3 way ball-valve could work and be much simpler, so because I'm feeling lazy I thought I'd ask before I hit Paint.
  • 0

<A HREF="http://www.paisleypeking.co.uk"><IMG BORDER="0" WIDTH="400" HEIGHT="64" SRC="http://www.paisleypeking.co.uk/images/signature.gif"></A>
User avatar
SPG
Major
Major
 
Posts: 364
Joined: Thu Feb 09, 2006 11:55 am
Reputation: 0

Unread postAuthor: daccel » Sat May 16, 2009 3:20 pm

I don't have any concrete plans yet, but probably .375-.75" barrel, with a small high mix chamber, if it's possible to do high mixes with methanol. Not more than a few cu in if possible, just to make life difficult :wink:.

Out of curiosity, I tried using starter fluid (ethyl ether, aliphatic naptha, co2... but doesn't give proportions) without any real measurement in my mini piston hybrid. Just sprayed a bit on the end of the schrader until it looked like there was a few drops sitting in it, put on the pump and forced the fuel through the valve with the air.

At first nothing, but after flushing a few pumps of air through, it fired. Then the interesting part, added a few fresh pumps of air without more fuel and it was able to fire again.

I think I tried the same before with methanol with no ignition, but I'll double check it later today to make sure.

So perhaps the starter fluid is a viable option for micro chambers which are hard to meter. Or I should stop trying to be different and shell out for one of those expensive pressure gauges and use propane :roll:.


Edit: Tried methanol again in the mini hybrid, but no variances in fuel/air could get it to ignite.

Tried starter fluid again and filmed it for your viewing pleasure. Valve has an opening pressure of ~50 psi, which I filled it to. The pressure returns to this after the combustion spike. Each pump after is basically flushing the chamber. Looks promising if it can fire that consistently, because it means it's vapourizing rapidly and under pressure. I suppose the chamber warming after each shot would help with this.

[youtube]http://www.youtube.com/watch?v=xVp-HWpSO3s[/youtube]
  • 0

User avatar
daccel
Donating Member
Donating Member
 
Posts: 238
Joined: Thu Oct 11, 2007 9:51 pm
Location: BC, Canada
Reputation: 0

Unread postAuthor: daccel » Mon May 18, 2009 11:16 pm

Well, I think I'm going to pursue ether as a fuel, given the promise it shows.

Eventually a hybrid version of Rambo's auto combustion, perhaps?

But since my complex projects don't seem to get far off the ground, I'd like to throw something simpler together for now to experiment with the fuel. Enter the picture, below.

It's really just your basic piston hybrid, likely made out of 3/4" copper. But for fueling you would unscrew the cap on the bottom and spray in the starter fluid to saturate the fiberglass. The fuel would then wick up the fiberglass into each arm of the chamber to enhance vapourization. But would the addition of fiberglass possibly be overkill, and lead to a rich mix out of flammability range?
  • 0

Attachments
ether1.jpg
ether1.jpg (24.56 KiB) Viewed 370 times
User avatar
daccel
Donating Member
Donating Member
 
Posts: 238
Joined: Thu Oct 11, 2007 9:51 pm
Location: BC, Canada
Reputation: 0

Unread postAuthor: Technician1002 » Mon May 18, 2009 11:21 pm

daccel wrote:Well, I think I'm going to pursue ether as a fuel, given the promise it shows.

Eventually a hybrid version of Rambo's auto combustion, perhaps?

The fuel would then wick up the fiberglass into each arm of the chamber to enhance vapourization. But would the addition of fiberglass possibly be overkill, and lead to a rich mix out of flammability range?


A wick provides a huge variable to the metering of fuel. How much evaporates? How much resudial is remaining to make the next shot too rich, etc.. Is the chamber warmer after a couple shots? It would be a liquid spray and pray.

It's best to have a fresh dry chamber for each shot and a metered amount of fuel fully evaporated for consistant shots.

The multiple shots indicate the mix is too rich as you have unburned fuel left over.
  • 0

User avatar
Technician1002
Chief of Staff
Chief of Staff
 
Posts: 5190
Joined: Sat Apr 04, 2009 11:10 am
Reputation: 14

Unread postAuthor: daccel » Mon May 18, 2009 11:58 pm

Well it would be easy enough to do some trial and error with and without a wick, I suppose.

Forgot to show it in the diagram, but the idea is to have a small pool of fuel at the bottom to allow multiple shots without manually re-fueling.

Agreed, that is what you'd ideally want. But I'm willing to sacrifice some efficiency/power/accuracy for ease of construction/use, if I can make it fire reliably.

While it is likely, the multiple shots don't necessarily indicate a rich mix, because the mix could be accurate in terms of vapourized fuel, but with liquid fuel sitting in the chamber that subsequently vapourizes and mixes with the next batch of air. Optimistic, perhaps, but in theory... :D.
  • 0

Attachments
ether2.jpg
ether2.jpg (24.85 KiB) Viewed 360 times
User avatar
daccel
Donating Member
Donating Member
 
Posts: 238
Joined: Thu Oct 11, 2007 9:51 pm
Location: BC, Canada
Reputation: 0

Previous

Return to Hybrid Cannon Discussion

Who is online

Registered users: Bing [Bot], Google [Bot], MSNbot Media, Yahoo [Bot]

cron
Reputation System ©'