Pneumatic Air Cylinder Telescopic Mega Tree Pole

**ags0000** · 06-21-2012, 12:14 AM

No matter what design guardbanding (over-spec) is on this project, please, please be sure to install a pressure relief valve on the metal pipe rated at about 25% of the working pressure that the bottom pipe is rated for. Things like this seem to find ways to surprise the best of engineers. Think of Jurassic Park, or that power generation plant in Japan - or how Purdue University found it's mascot name...

Also: I was surprised when I weighed all the components of my megatree for 2011 and realized it weighed more than 400 lbs!

**walter monkhouse** · 06-21-2012, 12:19 AM

You really have something good there if you could regulate the air pressure for a smooth assent and descent of the pole. Maybe you could develop a chart that shows how much pressure to lift and lower a given amount of weight smoothly. Congrats on the effort and confidence you have put into this project. Walter

**Barnabybear** · 06-21-2012, 02:39 PM

please be sure to install a pressure relief valve on the metal pipe rated at about 25% of the working pressure that the bottom pipe is rated for

+1 on that you can never be to safe with pressureised objects.

You really have something good there if you could regulate the air pressure for a smooth assent and descent of the pole.

If you feed the air into the pipe through a very small hole (or valve - flow not pressure) the speed should self regulate. As I understand the moving tube (piston) is capped on the bottom / inner end, so there is a relatively small area inside the ‘chamber’ when the ‘piston’ is in its down position. The pressure will build up until it overcomes any downward force and the ‘piston’ will move upwards, as it does it will increase the area within the chamber reducing the pressure, thus reducing the upward force. The size of the small hole or valve will control how quickly the pressure can be restored. You should be able to control the speed of ascent quite accurately.

**n8huntsman** · 06-21-2012, 04:42 PM

The problem once you overcome static fircition, dynamic friction is always less. Therefore, without some sort of spring, as soon as you reach the pressure required to break static friction, there is nothing to prevent it from going to the top. What you need is an orifice that will only allow air to enter the chamber at a low rate. This will ensure that as the pole rises and the air chamber volume expands, it can only be filled at a modulated rate. My air compresser has a fairly large tank and does not limit the CFM very well. A smaller compressor with a lower CFM tank would allow the pole to rise with much more control.

edit: I hadn't refreshed my window from this morning so I did not see the previous post till after I posted. Very similar posts. I'm in complete agreement.

**CaptKirk** · 06-21-2012, 09:00 PM

All this talk about air pressure and a self regulating orifice is just wrong some how..

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**n8huntsman** · 06-21-2012, 09:28 PM

Originally Posted by ags0000

No matter what design guardbanding (over-spec) is on this project, please, please be sure to install a pressure relief valve on the metal pipe rated at about 25% of the working pressure that the bottom pipe is rated for. Things like this seem to find ways to surprise the best of engineers. Think of Jurassic Park, or that power generation plant in Japan - or how Purdue University found it's mascot name...

Also: I was surprised when I weighed all the components of my megatree for 2011 and realized it weighed more than 400 lbs!

My compressor is incapable of going over 120 psi.

**Jrd** · 06-26-2012, 04:19 PM

Wow Nate, 2 concrete blocks is pretty good but maybe it's time to figure out how your going to mount this thing to the ground and do that before testing continues...

**walter monkhouse** · 06-26-2012, 10:55 PM

Nate,
You have a concept going with great potential, but it needs to be tested thoroughly. Try rigging up something similar to the JUMP test to test your pneumatic pole. See the attached picture with 400#'s of concrete blocks.

**n8huntsman** · 07-02-2012, 11:31 PM

I got all 32 wire rope strings cut and crimped. I formed an 8'Ø base and looped it through the wire rope. This is a video of it rising. RGB strings to come!