SpudFiles

Hello to everybody at Spudfiles from the Midlands, England.

I have some questions regarding a hybrid I'm planning with my girlfriend. I've built 2 combustion launchers in the past but looking for something that is more of a challenge to build. Of course the increased power is also appealing.

Specific plans and information on hybrids seems a little difficult to obtain - The most comprehensive sources have been forums so I thank the owner here and all the members for sharing your knowledge.

Now a few questions that are unanswered in my mind. I'm very much of the opinion 'go and find out yourself' so I have previously done research on any questions I ask - I know repeating the obvious is tiresome.


1. I have a friend who is a scaffolder and he is getting me a 500mm (20") length of pipe for a chamber. I've not decided on length yet but the pipe is 48mm OD 4mm wall. This gives me approx 40mm id. I need to find an endcap and have seen scaffold handrail fittings which should work well once welded on. I just need to check if the end is enclosed fully. Seem ok so far? http://www.ebay.co.uk/itm/132-Tube-clam ... 2a2f2bd093

For the barrel I think the easiest method for attachment would be to use something 40mm od. Firstly insert 2" as a reducer sliding it 1" into the barrel and secure by welding. Then comes the fitting to hold a burst disk followed by the 40mm od barrel. Should I stick to galv steel or does it weld sufficiently to other materials like stainless?

I cant decide which would be best as a quick release burst disk fitting. Would a hydraulic flat faced coupling work? If not what would you recommend and where can i get it from in England?

I have got myself a flyback transformer out of an old crt tv to use for ignition. This will run from a battery and a 555 oscillator to tune the frequency of the sparks. Should i use a spark plug threaded into the chamber?

My final question is regarding tyre filling valves. Are they man enough to stand up to the pressure or do they need protecting somehow?

Thanks, Chris

vxrtol wrote:I have some questions regarding a hybrid I'm planning with my girlfriend.

Bit weird... nice find hehe

Specific plans and information on hybrids seems a little difficult to obtain

There's a reason for that, we don't want idiots making them and hurting others and/or themselves

I have a friend who is a scaffolder and he is getting me a 500mm (20") length of pipe for a chamber. I've not decided on length yet but the pipe is 48mm OD 4mm wall. This gives me approx 40mm id. I need to find an endcap and have seen scaffold handrail fittings which should work well once welded on. I just need to check if the end is enclosed fully. Seem ok so far?

Sounds about right. Does the tubing have a seam or is it drawn over mandrel? What mix numbers where you planning on running?

I cant decide which would be best as a quick release burst disk fitting. Would a hydraulic flat faced coupling work? If not what would you recommend and where can i get it from in England?

Something likethese?

If that's what you're refering to, how would it hold a burst disk?

I would have thought something like this is a better idea:

I have got myself a flyback transformer out of an old crt tv to use for ignition. This will run from a battery and a 555 oscillator to tune the frequency of the sparks. Should i use a spark plug threaded into the chamber?

That's an easy way of doing it with off-the-shelf parts.

My final question is regarding tyre filling valves. Are they man enough to stand up to the pressure or do they need protecting somehow?

They're pretty hardy, I've used standard tyre valves in hybrids up to 28x without any issues.

Something like these?

If that's what you're refering to, how would it hold a burst disk?

I would have thought something like this is a better idea:

Exactly, I think that was something what he want. That is why he is not able to reply with this message because that is what he want or maybe he has another reason.

jackssmirkingrevenge wrote:

vxrtol wrote:I have some questions regarding a hybrid I'm planning with my girlfriend.

Bit weird... nice find hehe

Lol or she assumed it's some kinky sex idea

"Hey babe, we're staying in tonight - I've got a lighter refill can, clingfilm and a syringe, it's going to be one heck of a party "

or she misunderstood the word combustion / he mispronounced it


ok this is getting slightly NSFW

Gone down a more popular avenue.

Just a quick mock up before thread sealing and fuelling pipe work.


1" union - looks like fun trying to seal the tapered edge.
2" chamber with 1" plug for electrodes
1/2" from ball valve
Pn32 ball valve

Any criticism/ suggestions welcome.

Chris

Looking good!

1" union - looks like fun trying to seal the tapered edge.

I believe the fashion is to grind this flat.

Have a look here: http://www.spudfiles.com/hybrid-cannons ... 42-75.html

Thanks for the link Jack

Today I've had somebody with a grinder remove the bit suggested. Just a slight ridge on a small part of it but I'll file that flat.

Am I right in thinking the union fitting 'sandwich' goes in this order:
Chamber side -----|rubber washer, burst disk(s)|-------- barrel side

Final question -

Will pressurising a gauge (15psi) to more than it reads damage it? To clarify, I'm using two gauges and not sure if I need a ball valve to protect the sensitive one when adding air.

Many thanks, Chris

vxrtol wrote:Will pressurising a gauge (15psi) to more than it reads damage it?

Yes, immediately and beyond repair.

Picked this up yesterday