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Author Topic: How can I improve the range of a vacuum cleaner bazooka?  (Read 11939 times)

Offline Make it Lady

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I have just made a vacuum cleaner bazooka as featured on www.planet-scicast.com and was expecting the missiles to go quite far. They go just less than a meter and I'm heartily disappointed. Do we have any backyard balistics fans in the house who could suggest improvements?
« Last Edit: 04/03/2008 23:20:24 by chris »


 

Offline JimBob

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Re: How can I improve the range of a vacuum cleaner bazooka?
« Reply #1 on: 29/02/2008 02:52:27 »
Use smaller tubes and accelerate the output from the vacuum cleaner by narrowing the output down with a cone. And make the top one longer so that there is a longer time for acceleration of the object being shot.

You could also cheat.

::)

Get an industrial strength vacuum cleaner with a 400 horse power motor - http://www.industrialvacuum.com/rent1.html
 

Offline daveshorts

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Re: How can I improve the range of a vacuum cleaner bazooka?
« Reply #2 on: 29/02/2008 10:04:10 »
I would have thought that how well the projectile fits is important as too tight and there will be a lot of friction and too loose and you won't build up a large pressure difference.

The other thing is have you put a piece of card over the end, as otherwise the pressure difference definitely won't build up.

Hopefully it works as I want to build one in the next week or so for a show I am doing for the Cambridge Science Festival
« Last Edit: 29/02/2008 10:07:54 by daveshorts »
 

Offline Make it Lady

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Re: How can I improve the range of a vacuum cleaner bazooka?
« Reply #3 on: 29/02/2008 17:27:50 »
Thanks JimBob. I will try that first thing tomorrow. I'm supposed to be showing people how to Make It at 11am tomorrow. Nothing like flying by the seat of your pants. As for projectiles Loser seems better than snug and then when you put the card on the end you have to hold the projectile in the other end for a lot longer than you think. It helps if you have three hands which I'll have to work on. Cambridge Science Festival heh! would love an invite next year. I'd like to spead my wings a bit.
 

Offline daveshorts

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Re: How can I improve the range of a vacuum cleaner bazooka?
« Reply #4 on: 29/02/2008 17:41:03 »
Something else I thought of, was that it may help to put the card off centre, so when it gets hit from behind the card rotates rather than just being pushed straight off

I am afraid don't run the booking people part of the festival, I am just involved in CHaOS (www.chaosscience.org.uk), plus the physics department open day for historical reasons, and I am doing an as yet undetermined number of talks for CHaOS... I have to  build many many things in the next fortnight, including a safe gherkin electricution machine.
 

Offline Karen W.

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Re: How can I improve the range of a vacuum cleaner bazooka?
« Reply #5 on: 29/02/2008 18:35:40 »
We used to shoot wild cucumbers out of my neighbors old piggy vacuum cleaner!! LOL!!

It was great fun... LOL We were all of about 10 or 12 years old!!

Thanks for the links!
« Last Edit: 29/02/2008 18:40:54 by Karen W. »
 

Offline daveshorts

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Re: How can I improve the range of a vacuum cleaner bazooka?
« Reply #6 on: 29/02/2008 22:28:19 »
I have just built one using about 1.4m of 32mm push fit waste pipe from B&Q, and a T joint fitting. It seems to have a range of about 6m with about a 3 degree elevation. The house isn't big enough to try any more elevation.
 

Offline Bass

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Re: How can I improve the range of a vacuum cleaner bazooka?
« Reply #7 on: 29/02/2008 22:30:36 »
Don't know much about vacuum cleaner bazookas, but we used to make potato guns that would launch a potato over 100 meters
 

Offline JimBob

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Re: How can I improve the range of a vacuum cleaner bazooka?
« Reply #8 on: 01/03/2008 14:49:02 »
OK - Report in - how did the changes work?
 

Offline Make it Lady

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Re: How can I improve the range of a vacuum cleaner bazooka?
« Reply #9 on: 01/03/2008 17:27:18 »
I was in quite a small room so I couldn't go for more than about 2 meters in the end. What really seemed to help was holding the missile for as long as you could stand the vacuum wining for and then let go. Elevation was difficult too as we were indoors with a low ceiling so I didn't get to check that out. The off centre card was good as hitting the card really slows it the projectile down.
I couldn't use the plumbing pipe as the whole idea of my talks is getting science out of stuff that is lying around your home but I may try this for my own amusement!!!!!
The childminders were amazed by it all and not only was my workshop oversubscribed but no one said anything nasty on the feedback form which is quite a feat. I'm shattered now and basking in my own glory.
Oh yes JimBob the making of weaponry is all part of the war you know. What are you going to build when I come knocking with my vacuum cleaner bazooka army?   

 

Offline JimBob

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Re: How can I improve the range of a vacuum cleaner bazooka?
« Reply #10 on: 01/03/2008 18:04:54 »
A strong pot of lye through the murder holes of the castle gatehouse.
 

Offline Professor Gaarder

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Re: How can I improve the range of a vacuum cleaner bazooka?
« Reply #11 on: 01/03/2008 18:32:38 »
lol I used to love stuff like this. I guess I still do.

I used to have a marshmellow blow gun that could shoot over 30 feet, and I suppose this is just that inverted.

now, what are you trying to shoot? catch me up. maybe I can help.

what you need is a good wedge, something that can hold the ammunition in place while pressure builds up, so you can release the wedge at the push of a button and send the projectile flying.

however, what you are shooting ultimately decides what you need, and the previous posts are too vague for me to grasp what exactly it is.
 

lyner

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Re: How can I improve the range of a vacuum cleaner bazooka?
« Reply #12 on: 01/03/2008 18:42:45 »
Quote
Use smaller tubes and accelerate the output from the vacuum cleaner by narrowing the output down with a cone.
That would be the intuitive approach.
However, the energy imparted to the projectile will be equal to the CSArea of the bazooka barrel times the pressure difference produced by the vacuum cleaner times the length of the accelerating section.
The vacuum cleaner will very likely be designed to have an optimum diameter of tube for the best pressure difference so 'funneling it down' is unlikely to help. The best thing is to have as long an acceleration tube as is practical, coupled with a short final section and as few leaks as possible.
 

Offline Make it Lady

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Re: How can I improve the range of a vacuum cleaner bazooka?
« Reply #13 on: 01/03/2008 20:39:06 »
Prof. I have already done the shooting today and just wanted it to go as far as possible but for future use I would like to shoot Doctor Beaver and JimBob as they have declared war upon me. Ane me a Lady too.
Sophie, yes I tried the tube narrowing and it was rubbish. I did the tube lengthening and it did have a bit of an effect but best was to build up the vacuum before releasing the projectile. I didn't try an industrial vacuum but I think that would help a lot. obviously time constraints and budget prevented this.
Dave shorts, I nearly booked you lot once for Intech but my evil CEO wouldn't let me.
 

Offline JimBob

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Re: How can I improve the range of a vacuum cleaner bazooka?
« Reply #14 on: 01/03/2008 21:04:57 »
"... but for future use I would like to shoot Doctor Beaver and JimBob as they have declared war upon me.

Doctor Beaver has disavowed my actions, the coward, and in his words is " hiding in the bushes and watching." What a whimp.

Ane (sic) me a Lady too.

This is questionable.
 

paul.fr

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Re: How can I improve the range of a vacuum cleaner bazooka?
« Reply #15 on: 01/03/2008 21:22:21 »
... I have to  build many many things in the next fortnight, including a safe gherkin electricution machine.

Slightly off topic. but what's the difference between a gherkin and (what is usually used) a pickle? Honestly, i don't know.

Does a gherkin have a higher salt content? You should get better results with whichever has the higher salt content, shouldn't you?
 

Offline Make it Lady

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Re: How can I improve the range of a vacuum cleaner bazooka?
« Reply #16 on: 01/03/2008 22:03:54 »
In the UK a pickle is anything that has been left in vinegar for a long time or a problem that is difficult to get out of.
 

Offline JimBob

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Re: How can I improve the range of a vacuum cleaner bazooka?
« Reply #17 on: 01/03/2008 22:20:41 »
gher-kin (gūr'kin)  n.
       1.  the small immature fruit of a variety of
           cucumber, used in pickling.
 

Offline Make it Lady

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Re: How can I improve the range of a vacuum cleaner bazooka?
« Reply #18 on: 01/03/2008 23:04:24 »
According to the book "The very hungry caterpillar" a pickle and a Gherkin are one and the same in US.
It is the sodium in the Gherkin that makes it glow like a street light.
 

Offline daveshorts

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Re: How can I improve the range of a vacuum cleaner bazooka?
« Reply #19 on: 01/03/2008 23:33:13 »
Sophie, yes I tried the tube narrowing and it was rubbish. I did the tube lengthening and it did have a bit of an effect but best was to build up the vacuum before releasing the projectile. I didn't try an industrial vacuum but I think that would help a lot. obviously time constraints and budget prevented this.
I don't think you want a tube any wider than the vacuum hose you are using as the cleaner only sucks down to about .9 bar so the projectile speed is going to be roughly limited by how fast the air is moving.
Quote
Dave shorts, I nearly booked you lot once for Intech but my evil CEO wouldn't let me.
Are you still interested? As we are looking for places to go in the weekends of this year's tour.
 

Offline Make it Lady

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Re: How can I improve the range of a vacuum cleaner bazooka?
« Reply #20 on: 02/03/2008 21:11:14 »
Sorry Dave don't work there anymore but call 01962 863791 and ask for Angela. They are busy with the new planetarium at the moment and they are not always open for new ideas (that's why I left.) But give it a try.
 

Offline Make it Lady

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Re: How can I improve the range of a vacuum cleaner bazooka?
« Reply #21 on: 03/03/2008 22:32:20 »
Anyway did you give the Gherkin a fair trial?
 

Offline Karen W.

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Re: How can I improve the range of a vacuum cleaner bazooka?
« Reply #22 on: 03/03/2008 23:31:41 »
Don't know much about vacuum cleaner bazookas, but we used to make potato guns that would launch a potato over 100 meters
My husband favorite thing was building cannons  with steel pipes and potato shooters.. using pvc piping with the threaded inside end.. about 1 six inch in diameter pipe about 12 to 24 inches long, tapering down to a 2 or 3 inch round pipe about 4 feet long.
The large end needs to be threaded so a cap can be used to enclose the ether which will propel the potato when ignited.

You need to drill a whole about 1/2 inch in diameter so you can close it off with your thumb after giving a squirt of ether through the cap.
 
So build it, add the potato,  add a squirt of the ether in through the bottom, covering the small hole.. recap the end. Light with a fireplace lighter or match after removing thumb from ignition hole.. making sure you have a clear shot for at least a 3  to  3 and  1/2 city blocks...

You may set it into a curved angled platform to point it for elevation.. or just hold it, but our preference for safety was to prop it...

They were fun..
 

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Re: How can I improve the range of a vacuum cleaner bazooka?
« Reply #22 on: 03/03/2008 23:31:41 »

 

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