TEST YOUR ENGINEERING SKILLS

[Hsing-ee]

I used to work for a newspaper that was on a sort of island, surrounded by a river and a canal which were linkedby little channels. Every year each department of the newspaper made a boat and teams of four would paddle the boats around the 'island', the winners getting a barrel of beer at the local pub. This dosen't seem so difficult, but the boats had to be made entirely from copies of the newspaper, plus glue and marine dope varnish etc. It was great fun.

I was thinkning about this, and thought maybe it would be a fun idea for the engineers in the audience to compete to make the most powerful/accurate spring/piston airgun based around a bicycle pump as its "cylinder". Testing to be done at one of the LV big meets. Sort of a Robotwars/scrap racer type thing for airginners.

I know this is lining myself up for a massive slagging, you are all right it is a stupid idea, but I think therein lies its genius.

[Maxticate]

the idea. But how much pressure can a bicycle pump tube take before exploding ?

[Ste]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Max:
the idea. But how much pressure can a bicycle pump tube take before exploding ?[/quote]

I can't wait to find out <img src="http://jsramsbottom.co.uk/bbs/e/icon_biggrin.gif" alt="Big Grin" width="15" height="15"><!--graemlin::D-->

[Hsing-ee]

Dunno what pressure they can take but the technology has not been staying still any more than air-rifle technology has ... you might want to try modifying a Super Soaker watergun to fire pellets with a dump-valve too but that does not fit the spec ...

[hareng]

Even the rare and hard to find aluminium jobbies wont handle even 100psi yet alone 100 bar.
A well designed and made valve should give sufficient power at 35bar for indoor use, 50bar+ for full legal power depending upon caliber.
Could make a water pistol out of one though, but could be classed as a section 5!

[Hsing-ee]

what is the pressure inside a springer chamber on average then at the peak of its compression?

[Sid]

Ask the Cardews, not us <img src="http://jsramsbottom.co.uk/bbs/e/icon_biggrin.gif" alt="Big Grin" width="15" height="15"><!--graemlin::D-->

Seriously, that is one clever and fun idea....

[ianc]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Fosberry38:
what is the pressure inside a springer chamber on average then at the peak of its compression?[/quote]

Around 1250psi (p57 of the Cardews book).

Rgds,

Ian

[rich]

Well, if it helps, I pressure tested a new hot water system last week by pumping it up with air using a bicycle pump. It's off a combi boiler so it can get to mains pressure. I wanted to get it up to 4 bar. The plastic bicycle pump couldn't take the work load.

At just before 4 bar the pump washer pushed itself backwards into the hollow shaft and spread the thin wall tube out like a flower head. The plastic outer cylinder of the pump showed no sign of failing, neither did the connecting hose, although the hose did get pulled off the pump once due to my ham-fistedness.

And yes, I was mightily inspired to try to fill the pipework from my 300 bar diver's bottle. Fortunately for me and the new pipework I didn't have the right adaptor. <img src="http://jsramsbottom.co.uk/bbs/e/icon_biggrin.gif" alt="Big Grin" width="15" height="15"><!--graemlin::D-->

rgds

Rich

[nightjar]

What a great idea.
Though perhaps to make it fair there should be two classes.

Class 1. For the engineering wizards, who have access to lathes, welders etc.

Class 2. For the araldite and string brigade. Namely me

The prize?
Well how about the winner has his weapon gold plated and mounted
on a well figured walnut plinth? <img src="http://jsramsbottom.co.uk/bbs/e/icon_wink.gif" alt="Wink" width="15" height="15"><!--graemlin:;)-->

I'm off to the bike shop now. <img src="http://jsramsbottom.co.uk/bbs/e/icon_wink.gif" alt="Wink" width="15" height="15"><!--graemlin:;)-->

Rick

[ROVER]

I think it's a great idea , now where did I leave that stirup pump and elastic bands ?

[fullmetaljacket]

.

[This message was edited by fullmetaljacket on 14 October, 2003 at 8:12.]

[max headroom]

AHA, do i read this as a spud gun challenge.

[Maxticate]

I'd like to add duck tape to the discussion being part of the araldite and string brigade myself.

If we wrapped the bicycle pump body with a shed load of duck tape then what pressure could it handle ??

[fullmetaljacket]

*giggles at visions of waterfowl packaged in large quantities of adhesive tape*

surely you meant ducT tape <img src="http://jsramsbottom.co.uk/bbs/e/icon_biggrin.gif" alt="Big Grin" width="15" height="15"><!--graemlin::D-->

I second that proposal... can we include rubber bands and paperclips?

[Hsing-ee]

... or should the spec. be widened to an airgun made using anything available from a B&Q or Homebase store?

[unqualifieduser]

...and sticky-back plastic. No project could be complete without the traditional Blue Peter magic ingredient <img src="http://jsramsbottom.co.uk/bbs/e/icon_biggrin.gif" alt="Big Grin" width="15" height="15"><!--graemlin::D-->

Seriously (as if) I think it's a brilliant idea.

Now... where did my Dad hide all my old bike bits...

Paul.

[linegeist]

Now I have, sitting here, a brass-bodied football pump circa 1950-something with a leather washer.

I suspect this baby could handle fairly high chamber pressures - hmmmmmm <img src="http://jsramsbottom.co.uk/bbs/e/icon_smile.gif" alt="Smile" width="15" height="15"><!--graemlin::)--> <img src="http://jsramsbottom.co.uk/bbs/e/icon_smile.gif" alt="Smile" width="15" height="15"><!--graemlin::)--> <img src="http://jsramsbottom.co.uk/bbs/e/icon_smile.gif" alt="Smile" width="15" height="15"><!--graemlin::)--> <img src="http://jsramsbottom.co.uk/bbs/e/icon_smile.gif" alt="Smile" width="15" height="15"><!--graemlin::)-->

Hang on workshop - here I come!! <img src="http://jsramsbottom.co.uk/bbs/e/icon_biggrin.gif" alt="Big Grin" width="15" height="15"><!--graemlin::D--> <img src="http://jsramsbottom.co.uk/bbs/e/icon_biggrin.gif" alt="Big Grin" width="15" height="15"><!--graemlin::D-->

regards
BC

[Maxticate]

but if we take a closer look at the rules

fosberry 38 clearly states in line 8

"based around a bicycle pump as its "cylinder"."

So a football pump would be disqualified <img src="http://jsramsbottom.co.uk/bbs/e/icon_wink.gif" alt="Wink" width="15" height="15"><!--graemlin:;)--> <img src="http://jsramsbottom.co.uk/bbs/e/icon_biggrin.gif" alt="Big Grin" width="15" height="15"><!--graemlin::D-->

However could it be shown that the football pump had bicycle capability then it may just be allowed as it would be an MFP <img src="http://jsramsbottom.co.uk/bbs/e/icon_biggrin.gif" alt="Big Grin" width="15" height="15"><!--graemlin::D--> <img src="http://jsramsbottom.co.uk/bbs/e/icon_biggrin.gif" alt="Big Grin" width="15" height="15"><!--graemlin::D-->

[custarddog]

so a bicycle stirup pump should be ok then, are we able to use a bladder/storage facility?

i am off the check my health insurance and get the old motocross body armour out

[linegeist]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Max:
but if we take a closer look at the rules

fosberry 38 clearly states in line 8

"based around a bicycle pump as its "cylinder"."

So a football pump would be disqualified <img src="http://jsramsbottom.co.uk/bbs/e/icon_wink.gif" alt="Wink" width="15" height="15"><!--graemlin:;)--> <img src="http://jsramsbottom.co.uk/bbs/e/icon_biggrin.gif" alt="Big Grin" width="15" height="15"><!--graemlin::D-->

However could it be shown that the football pump had bicycle capability then it may just be allowed as it would be an MFP <img src="http://jsramsbottom.co.uk/bbs/e/icon_biggrin.gif" alt="Big Grin" width="15" height="15"><!--graemlin::D--> <img src="http://jsramsbottom.co.uk/bbs/e/icon_biggrin.gif" alt="Big Grin" width="15" height="15"><!--graemlin::D-->[/quote]

After an hour of swearing and cussing I've just managed to get 3 whole pumps of air into a bicycle tube using this brass 'thing' .......... therefore it's now a bicycle pump, innit? <img src="http://jsramsbottom.co.uk/bbs/e/icon_razz.gif" alt="Razz" width="15" height="15"><!--graemlin::p--> <img src="http://jsramsbottom.co.uk/bbs/e/icon_razz.gif" alt="Razz" width="15" height="15"><!--graemlin::p--> <img src="http://jsramsbottom.co.uk/bbs/e/icon_razz.gif" alt="Razz" width="15" height="15"><!--graemlin::p--> <img src="http://jsramsbottom.co.uk/bbs/e/icon_razz.gif" alt="Razz" width="15" height="15"><!--graemlin::p--> <img src="http://jsramsbottom.co.uk/bbs/e/icon_razz.gif" alt="Razz" width="15" height="15"><!--graemlin::p--> <img src="http://jsramsbottom.co.uk/bbs/e/icon_biggrin.gif" alt="Big Grin" width="15" height="15"><!--graemlin::D-->

Rudegards
BC

[Maxticate]

An independent judicial enquiry has awarded le git legal entry for perserverence in the face of adversity. <img src="http://jsramsbottom.co.uk/bbs/e/icon_biggrin.gif" alt="Big Grin" width="15" height="15"><!--graemlin::D-->

In other news I'm confused after custard dogs comment about bladder and storage tanks. I thought the bicycle pump tube was the storage tank. Or are we just using it to pump up a chamber ??