longest hose off of an air compressor…
I am happily in the midst of a summer science program and we are building water bottle rockets (hook a 2 liter bottle to a pvc tripod add water air, and whoosh..) the launcher is a commercial rig from pitsco, and has a pressure blow off valve… although the valve stuck and I blew up a 2L bottle today…. really loud. Louder than a gun.
So, instead of pumping up 40 bottles to 90 psi I am wondering if I can make my thomas 635hd usefull… I was thinking about hooking it to a 20amp outlet with a 50 foot 10 gauge extension cord and then running my 50 foot flexeel, and then another hose to the launcher…. probably home desperates finest 100 footer….
does anyone see a problem with this? my goal is not to hurt the compressor, but the pumping is getting really old..
jeff
Replies
should work...
gonna use 3/8???
Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming
WOW!!! What a Ride!
Forget the primal scream, just ROAR!!!
I was thinking about scoring one of the new uber flex eel hoses in 100 feet. I really needed it. really.... the other thought I had was a 10 gallon air tank, but i am not sure how well it would last or, how happy the thomas would be filling it up.
dunno.
jmmmm
Edited 7/17/2007 6:38 am ET by jerseyjeff
We regularly run that much extension and hose
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I think you'll have a problem getting enough air volume to the launcher. You don't say the CFM of the bots but but my guess is the 40 bots @ 90 psi is a large volume relasead at 1 time. Any idea of how many CFMs the bottles provide @ launch? Compare that with what the compressor is putting out & reduce a bit for hose length. The bigger the hose the better for CFM delivery, 3/8 may too restrictive. I think Northern Tool has 1/2 id. Can you use the compressor to recharge the bottles?
Used to make rockets similary using dry ice, water & a home made adjustable cork/stopper (rubber grommets/o-rings stacked on a bolt with a wing nut to adjust tension) and could regulary get them higher than the 90' hangar doors where I used to work. Never grenaded one though. Probably would've got canned if we ever got caught.
oops, forgot to mention, I will be bringing each bottle up to 90 psi one at a time on the launcher... according to google each bottle will eat up .0529 cfm of 90 psi air... not too much.... currently using a bike pump, but that is NO FUN...
jmmmm
well if that's the case (those bottles are small), you might be able to have some fun with the compressor hooked right to the launcher. :O) Whatever valve you use will have to be fast so you get a good rush of air into the launcher and not a bleeding ramp up to max. Have you compared the CFM released form the bottles to what the compressor can put out @ 90psi? Charging the bottles with the compressor won't be an issue at all. Airhose length doesn't affect the compressor at all.
edit for spellcheck
Edited 7/18/2007 7:14 am ET by john7g
You won't hurt the compressor with the hose run.
The compressor just views the long hose as additional air tank volume. The initial pressurizing of the compressor will take longer due to increased volume. After initial pressure is built there is no difference.
If you really wanted to be careful you could pressurize the tank only, then add the hose one section at a time, letting the compressor catch up between sections. I would just plug the whole mess together and let it rip.
Sounds like fun.
Jim
Never underestimate the value of a sharp pencil or good light.
http://forums.taunton.com/tp-breaktime/messages?msg=84130.82this
this is from the head tech at Rolair Compressor...Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming<!----><!----><!---->
WOW!!! What a Ride!Forget the primal scream, just ROAR!!!
I've got probably 100' of 3/8" flexeel hose.
since I went to the 1/4", I haven't used the 3/8. You're welcome to it if you like.
oooh... say, you around today? I am going to need it for around 7pm tonight!!!
908-358-9205jmmmm
You're gonna shoot your eye out!
He's playing with soda bottles not the "Red Rider BB Gun"!!!!!
Ever seen the movie "A Christmas Story"???"No doubt exists that all women are crazy; it's only a question of degree." - W.C. Fields
The difference between men and boys is the size of their toys...
For that application, charging a 0.5 cf bottle, hose length is not a consideration. As someone said, it will just take a bit longer to bring the system up to pressure.
Your usage is only going to be .5cf per every couple of minutes. Should fill the bottle before you even get the valve all the way open.
2L = 0.07CF
90psi =~ 6 atmospheres
PSI desired when last water is exhausted = 7psi or 0.5 ATs
2L @ 0.5ATs = 0.1cf required in bottle at launch.
0.1cf @ 90psi =~ 0.015cf of volume
0.07 (2L) - 0.015 (Compressed air)= 0.055 or 1.56L
If you load your rocket with 1.56L of reaction mass, the last drop should be expelled with 7psi of pressure.
But wait! I haven't had all my coffee yet. I'm probably wrong.
SamT
When you end up needing emergency room treatment, do you have medical coverage for the trip?
there is a fairly reliable blow off valve build into the system that pops at 90 psi... so, I pressurize until I hit the valve.
jeff
oh, and i have excellent medical coverage.
jmmmm
Even easier: liquid nitrogen rockets! Or even solid CO2.
Edited 7/18/2007 7:06 pm ET by ChuckW
Did something similar when I taught 8th grade science. Sometimes I used the school's compressor, sometimes my own - both had attached tanks. I plugged the compressor in at the athletic shed near the soccer field and then ran hose to the middle. I believe I had well over 200 feet. The launcher came with its own smaller clear hose. Screwed a ball valve to a quick connect on one side and barb fitting for the clear hose on the other.
Set the regulator at the compressor for desired psi. Open the ball valve. Once the bubbles stop you are at the correct psi. Close the ball valve so it doesn't take forever to charge up the next one - the little clear hose holds very little and the 200 feet of hose won't lose its pressure. Pull the string and watch the launch. Compressor will kick on when tank pressure lowers, but with a decent regulator it will not affect you and with it 200+ feet away you can still talk over it.
For height, I made a protractor on a piece of cardboard and taped a piece of 1/2" copper to the top with washers hung on a string. I drew up the protractor in AutoCAD with the lengths marked instead of degrees assuming 50 or 100 feet from launch to observation. A 50 foot precut string was used to mark where students stood in different directions to measure the height - one sighting and one reading. Averaged the results to account for rockets going at an angle. You could put 50 foot on one side and 100 on the other - it's good to have variety for the variety of rocketry skills. Two lengths of the 50 ft string is quick to measure. Utility flags will keep them where they should be. I'd offer you the autocad file but I'm not sure where my school stuff went when I moved. I can give you the email of the guy who replaced me if you want to contact him.
Have fun!
this is a pretty high tech launcher, and all i need now is to be able to jump from 1/4" npt to a threaded barb... I am off to the grainger tomorrow...
jmmmm
Hey Jeff-
I don't know if it was your group, but there was an article w/ pic in the Star Ledger yesterday (Fri.) about shooting bottle rockets. The guy they mention is Aramis Gutierrez.
Actually, the article was about introducing boys and girls to "non-traditional" careers dominated by one sex. But it sounds more interesting with the rockets.
shep!
wasnt us.... but the hose worked great! The compressor easlily filled 2-3 bottles then cycled as it filled the rest...
jeff
jmmmm
did you scare any planes?
Darn !!!I thought this was another "biggest deck contest"
....
.
I found my Pants....
We had one 8 second flight.... it went scary high... I was really glad when it landed in the trees and didnt take out a car/passerbies.... good stuff...
really good time...
jmmmm
http://forums.taunton.com/tp-breaktime/messages?msg=84130.82this
this is from the head tech at Rolair Compressor...
Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming
WOW!!! What a Ride!
Forget the primal scream, just ROAR!!!
everytime I click on your link I get something interesting, but not much to do about air compressors. jmmmm
try this one..
http://forums.taunton.com/tp-breaktime/messages?msg=84130.82Life is not a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside, thoroughly used up, totally worn out, and loudly proclaiming<!----><!----><!---->
WOW!!! What a Ride!Forget the primal scream, just ROAR!!!
ahhh.... totally makes sense. I noticed that the 3/8" flexeel didnt go into insta tangle mode too.... I may start using the 3/8 line and plug a 1/4" coil line into that...
but for the rockets, it was PERFECT!
Jeffjmmmm