[McQueen (OP)]

The problem is one of energy!

[alancalverd]

Crap. You can generate a reasonable vacuum by modifying a bicycle pump.

[McQueen (OP)]

Good on you!

[RD]

So you are in effect admitting that the ‘vacuum elevator’ is theoretically impossible.

No such claim, pneumatic tube delivery systems do work but have an external energy supply : you've said yourself the ‘vacuum elevator’ uses a "small power input (3 KW motor)", (a 3kW generator operating continuously could heat and light a small home in the UK in winter).  Your 150Kg falling weight could only supply 3kW for a few seconds then its potential energy is used up and the machine will stop.

... RD for instance insists that there is no free energy, then how the hell did people sail around the world ?

Sailing is via wind power : harnessing the kinetic energy of moving air. Your proposed device doesn't use wind power : it has no source of energy other than the potential energy of the weight raised to a height.

Some people are obtuse.

At last we agree on something.

[RD]

... my design of a rotary pulse jet engine ( http://conceptengine.tripod.com/rpj/flywheel_assisted_rotary_pulse_j.htm

We at Green Initiative have designed a completely new type of engine ...

 [ You are not allowed to view attachments ]

http://conceptengine.tripod.com/rpj/flywheel_assisted_rotary_pulse_j.htm

Well not "completely new" : the basic design is at least 2000 years old  ... https://en.wikipedia.org/wiki/Aeolipile

BTW what is the pressure on the “compressed air/fuel mixture” due to centrifugal force as this mixture travels out toward the nozzles when the device is rotating at say 5000rpm ? , ( NB: fuel-air mixtures will explode when compressed sufficiently , as in a Diesel engine )

[McQueen (OP)]

The engine uses pre-compressed air from a tank that is topped up from time to time, a pressure of 125psi would be equivalent to a compression ratio of about 0:1.

[RD]

... a pressure of 125psi ...

Looks like you didn't follow my link about centripetal acceleration which the fuel-air mixture is going to experience as it travels outward towards the nozzles.



Rotating at say 5000 rpm,  ( 524 radians per second ), with a radius of say 10cm,
then the force on the fuel-air mixture at the nozzle will be about  27458 Newtons , ( that's 2800 times the force of gravity ). If the fuel-air line has a crossection of say 1cm² then that force causes a pressure of almost 4000 psi , (not "125psi").

So as your device spins-up the fuel-air mixture in the fuel-line in the rotor will increasingly be compressed by centripetal-force, soon reaching the point at which it explodes blowing the fuel-line apart.

[alancalverd]

The principle has been used to power helicopter rotors. Not a wild success, but interesting.

The idea of centrifugal compression ignition does however make it the more fascinating. Suppose we introduce a combustible mixture at the hub, and put a flame trap (as per Humphrey Davy) somewhere near the tip. Now start the rotor spinning. The centrifugal force will suck the mixture in at the hub, and the compression force will ignite it at the tip. Not a pulse jet but a continuous rocket.

[CliffordK]

You have a $140 donation.
Kick in $1000 of your own money if you wish.
And build your system in miniature. 

Look at engine parts.
A piston engine (or piston vacuum pump) has a vertical cylinder, with a piston that moves up and down.  The connecting rod and crankshaft gives you good vertical to rotary energy conversion, and usually already has a counterbalance built in.  Anyway, if you can't get it to work on small scale, then scaling it up certainly won't do much.

There are lots of vacuum pumps available, from small lab grade pumps to large industrial pumps. 

I've never actually seen a vacuum elevator.  Do you know where one is located that you can inspect and play with?  What is the Duty Cycle?  I'd assume that they likely have a large vacuum tank.  Evacuate the tank, and you can go up once or twice reasonably quickly.  Try to go up and down 10 times in rapid succession, and it may move slower than molasses....  unless it has an awfully big vacuum pump.

Although, I suppose I could imagine a 1HP electric winch connected to an elevator.  With good gearing, it should be able to lift the elevator in 30 seconds to a minute.  Theoretically a vacuum  pump should be able to do the same.

Anyway, all of your examples of what does work.  Steam Engine, Sailboat, Windmill, etc all have an external power source, and energy differential.  Without it, there is no energy captured.  The bane of the existence of all sailboats are days with no wind.  One can literally sit in one place and go nowhere.