Tethered wings.

"Pete Lynn" :

This is something I have been playing with for some time, basically a
lighter, cheaper and more versatile approach to wings.

It has the potential to greatly reduce the cost and increase the
effectiveness of aircraft and wind turbines. It should be of
considerable interest with regard to the air launch and recovery of
rockets. Enabling a fully controlled glide and soft vertical landing
for less than the weight of a parachute.

It should eventually yield around a five to tenfold cost reduction for
wind turbines, (around 0.5 cents per kilowatt hour), including the
capacity for far greater scale. Similarly it should advance aircraft by
near doubling payload/efficiency, reducing cost, reducing scaling
constraints, and allowing VTOL.

However, it is a little out there and will take many years to develop to
COTS levels.

http://www.inet.net.nz/~cbrent/pete/

Note, I only learnt how to make a website yesterday, it will get better.

I would like to thank you for doing experiments to test your ideas. Too
often we see just a lot of hot air (nothing but text and view graphs), May
suggest you use google to look up 'speed sailing' as the people involved this
are very interested in light wings, aso David Culp who is an expert at this.

http://www.dcss.org/speedsl/ should be a good start.

Earl Colby Pottinger

--
I make public email sent to me! Hydrogen Peroxide Rockets, OpenBeos,
SerialTransfer 3.0, RAMDISK, BoatBuilding, DIY TabletPC. What happened to
the time? http://webhome.idirect.com/~earlcp

"Earl Colby Pottinger" wrote in message
...

I would like to thank you for doing experiments to test your ideas.
Too often we see just a lot of hot air (nothing but text and view
graphs), May suggest you use google to look up 'speed sailing' as
the people involved this are very interested in light wings, aso David
Culp who is an expert at this.

http://www.dcss.org/speedsl/ should be a good start.


Actually the old man is with him at the moment. The tethered wing thing
is sort of the next step beyond all this. To be honest it is a little
more "high tech" and impure than they are really comfortable with.
Though they are coming around, slowly.

My father, also an engineer by training, is probably the leading world
expert on the design of kites in general, including such sailing craft.
He has been very prolific and is rather fast in the workshop, you can
probably imagine that my education has been long and intensive. I doubt
many understand design and development as well as he does, he lives it.

Even so, at the moment I find myself to be the one having to do the
pushing on this, they can little help me. :-(

Pete.

"Pete Lynn" :

"Earl Colby Pottinger" wrote in message
...

I would like to thank you for doing experiments to test your ideas.
Too often we see just a lot of hot air (nothing but text and view
graphs), May suggest you use google to look up 'speed sailing' as
the people involved this are very interested in light wings, aso David
Culp who is an expert at this.

http://www.dcss.org/speedsl/ should be a good start.


Actually the old man is with him at the moment. The tethered wing thing
is sort of the next step beyond all this. To be honest it is a little
more "high tech" and impure than they are really comfortable with.
Though they are coming around, slowly.

My father, also an engineer by training, is probably the leading world
expert on the design of kites in general, including such sailing craft.
He has been very prolific and is rather fast in the workshop, you can
probably imagine that my education has been long and intensive. I doubt
many understand design and development as well as he does, he lives it.

Even so, at the moment I find myself to be the one having to do the
pushing on this, they can little help me. :-(

Opps, did not know that you already know the best. And again like I said,
keep up the experiments, and may you have good luck with your design.

Earl Colby Pottinger

--
I make public email sent to me! Hydrogen Peroxide Rockets, OpenBeos,
SerialTransfer 3.0, RAMDISK, BoatBuilding, DIY TabletPC. What happened to
the time? http://webhome.idirect.com/~earlcp

"Pete Lynn" wrote in message ...
This is something I have been playing with for some time, basically a
lighter, cheaper and more versatile approach to wings.

It has the potential to greatly reduce the cost and increase the
effectiveness of aircraft and wind turbines. It should be of
considerable interest with regard to the air launch and recovery of
rockets. Enabling a fully controlled glide and soft vertical landing
for less than the weight of a parachute.

It should eventually yield around a five to tenfold cost reduction for
wind turbines, (around 0.5 cents per kilowatt hour), including the
capacity for far greater scale. Similarly it should advance aircraft by
near doubling payload/efficiency, reducing cost, reducing scaling
constraints, and allowing VTOL.

Interesting - I have seen proposal for kite flown wind turbines. These
use a kite shape to provide lift and channel the air into a central
how with a turbine. The main advantage is the more reliable winds at
greater height. Two main issues are landing and take-off in strong
wind for large non rigid structure, and the amount of area that each
structure needs, given it can rotate 360 degrees around a pivot.

"Alex Terrell" wrote in message
om...

Interesting - I have seen proposal for kite flown wind turbines. These
use a kite shape to provide lift and channel the air into a central
how with a turbine. The main advantage is the more reliable winds at
greater height. Two main issues are landing and take-off in strong
wind for large non rigid structure, and the amount of area that each
structure needs, given it can rotate 360 degrees around a pivot.

Yes.

If you then start moving the kite around, sweeping more of the sky and
building up apparent wind then your power output increases by a few
orders of magnitude and strong winds become but a small proportion of
flight speed such that they stop being an issue.

Launching and landing is the big problem, but you have enough thrust for
VTOL, so why not?

Pete.

Interesting - I have seen proposal for kite flown wind turbines. These
use a kite shape to provide lift and channel the air into a central
how with a turbine. The main advantage is the more reliable winds at
greater height. Two main issues are landing and take-off in strong
wind for large non rigid structure, and the amount of area that each
structure needs, given it can rotate 360 degrees around a pivot.

Yes.

If you then start moving the kite around, sweeping more of the sky and
building up apparent wind then your power output increases by a few
orders of magnitude and strong winds become but a small proportion of
flight speed such that they stop being an issue.

The reason a kite sweeps so fast acros the skyis that the lift vector
that pushes it foward only has to over come the drag on the strings.

As soon as you add a wind tubine on it to use the increased apparent
wind, the drag goes WAY up and the kite will slow down.

You won't actueally actually get the "power output increases by a few
orders of magnitude". The power output achievable is related purely to
the swept area of the turbine and the wing area of the kite

Launching and landing is the big problem, but you have enough thrust for
VTOL, so why not?

Pete.

"Hamish" wrote in message
om...

The reason a kite sweeps so fast acros the skyis that the
lift vector that pushes it foward only has to over come the
drag on the strings.

Yes, the same is true of a wind turbine, glider, yacht, aircraft, etc.,
hence glide or lift to drag ratio. Though you should really be thinking
of total drag, wing, line and propeller, the last being where you
extract/add energy from/to the system.

As soon as you add a wind tubine on it to use the
increased apparent wind, the drag goes WAY up and the
kite will slow down.

Of course, this is also how you extract energy from a standard wind
turbine and prevent over speed and over load. Though to clarify, lift
and drag coefficients are relatively independent of speed over this
range. As drag goes "WAY up" lift also goes "WAY up". Lift and drag
forces are proportional speed squared, hence power is proportion to
speed cubed, (mostly).

You won't actually get the "power output increases by a
few orders of magnitude".

Standard wind turbines would dispute that. A typicalish tip speed to
wind speed ratio of 10 is sort of a three order of magnitude power
increase, (for a given blade area), over say a drag type wind turbine
where the tip speed is limited to wind speed. Assuming swept area is
not a constraint, which it mostly is not for the kite system. Pushing
the Betz limit like wind turbines have to results in a lower effective
wind speed at the blade/kite, lower blade/kite speeds, a bigger and
heavier blade/kite, less power, etc.

Say your kite and lines has an overall L/D of 20, maximum power can
generally be extracted at an effective L/D of about half this, say 10.
Say the wind speed is 10m/s, max kite speed, (over speed condition with
no power take off), will be 200m/s, optimal power extraction speed will
be around 100m/s. The power roughly equals propeller drag force times
kite speed, (lift force *(1/10 - 1/20)*100m/s).

The power output achievable is related purely to the swept area of
the turbine and the wing area of the kite

Yes, swept area being far less of a constraint for the kite. It is far
cheaper to use a longer tether and sweep more of the sky than try to
extract the last bit of energy out of a small area as a wind turbine
must.

I think you are getting some of the details confused, think of a wind
turbine come kite, instead of the other way around. Kites perform like
wings, or wind turbine blades, not drag chutes.

Pete.

You won't actually get the "power output increases by a
few orders of magnitude".

Standard wind turbines would dispute that. A typicalish tip speed to
wind speed ratio of 10 is sort of a three order of magnitude power
increase, (for a given blade area), over say a drag type wind turbine
where the tip speed is limited to wind speed. Assuming swept area is
not a constraint, which it mostly is not for the kite system. Pushing
the Betz limit like wind turbines have to results in a lower effective
wind speed at the blade/kite, lower blade/kite speeds, a bigger and
heavier blade/kite, less power, etc.

Say your kite and lines has an overall L/D of 20, maximum power can
generally be extracted at an effective L/D of about half this, say 10.
Say the wind speed is 10m/s, max kite speed, (over speed condition with
no power take off), will be 200m/s, optimal power extraction speed will
be around 100m/s. The power roughly equals propeller drag force times
kite speed, (lift force *(1/10 - 1/20)*100m/s).

The power output achievable is related purely to the swept area of
the turbine and the wing area of the kite

Yes, swept area being far less of a constraint for the kite. It is far
cheaper to use a longer tether and sweep more of the sky than try to
extract the last bit of energy out of a small area as a wind turbine
must.

Funny thought. My initial thoughts were that the "swept area " you
extract power from would essentilly only be the area of the device,
not the area the device swings through ( presumably a horizontal
figure 8 ). then i though about

http://groups.google.co.nz/groups?hl...gy.rene wable

James Jones cant seehow a standard turbine works and " that most of
the wind goes straight through the huge gaps between the blages "

Almost found my self falling into the sam trap !!!!!!!

I dont think you will get any where near the betz limit for the entire
area, but even some of it would add up because it is a HUGE area


I think you are getting some of the details confused, think of a wind
turbine come kite, instead of the other way around. Kites perform like
wings, or wind turbine blades, not drag chutes.


The drag chut bit was only to simulate the performance change of the
kite a generator would have.

Been thinking on the whoe idea some more, Getting a Mw back to the
ground would require some pretty heavy " kits strings " ,and no one
would want to live within the swept area or within a fair distance of
it just in case the " string " broke, and a deacent sized one of these
would have a big footprint. Go off shore ? landings a lot softer too
but coastal and tidal flows could push it to directly upwind for the
new breeze.

Interesting idea,but risks and development costs make it very unlikly
any company would want to build it. Only way to start this off is to
build a say 10 Kw device on your own as a demenstrator and test it out
in the middle of nowhere

Pete.

If you then start moving the kite around, sweeping more of the sky and
building up apparent wind then your power output increases by a few
orders of magnitude and strong winds become but a small proportion of
flight speed such that they stop being an issue.

Thought of this just after I posted. To test out for yourself some of
what I said. get one of the kites, and attach a drouge chute to it
with an area say 1/10 of the wing, and see how much the performance
changes. I bet it won't sweep across the sky nearly as fast

"Hamish" wrote in message
om...

Thought of this just after I posted. To test out for yourself
some of what I said. get one of the kites, and attach a
drouge chute to it with an area say 1/10 of the wing, and
see how much the performance changes. I bet it won't
sweep across the sky nearly as fast.

Many years ago my father was flying a two line stunt kite around the
sky, backwards and forwards, up and down, looping it left and right. An
old man comes up to him, grabs him by the arm and says, "Young man,
young man, that kite would fly much better with a tail." :-)

Sorry, your statement while quite correct, left me kind of speechless.

Pete.