Power Kite Forum

mixers & pulleys & modifications... O my!

B-Roc - 11-8-2012 at 06:08 PM

Anyone other than me wonder why lower aspect kites like the Apex and Access use one or two pulleys in their mixer and higher aspect kites like the Montana, Frenzy, Eskimo, use 2 or 3 pulleys?

I know more pulleys can decrease bar pressure and I know on kites like the Outlaw they used the pulleys to change the camber as well as the AoA of the kite.

So my question is... do you think the lower aspect kites use less pulleys to decrease the cost of the kite or allow for heavier bar pressure or just because they are simpler kites?

I've often wondered how a kite maker decides what type of speed system they will use and why some go with 1, 2 or 3 pulleys.

Anyone ever tried adding a 3rd pulley to a 2 pulley mixer or a 2nd pulley to a 1 pulley mixer? Think it could be done without a major reconfig of the bridle based on the premade lengths of the bridle legs?

BeamerBob - 11-8-2012 at 11:21 PM

I know when I fly higher aspect fixed bridle kites, they have more pull so that could translate into more bar pressure on a depower. Maybe it is a combo of low AR kites are typically lower performance and lower priced (to simplify the discussion) so fewer pulleys help keep the price down, while being a lower AR kite, the added pulleys aren't as necessary either. Food for thought.

apextech - 12-8-2012 at 09:34 PM

I was always under the impression that the increase in pulleys on the higher aspect kites, even the lower performance kites from version to version (i.e. Apex II to Apex III) did reduce bar pressure as well as quickened up the steering for a faster turning kite. Though I know for a fact that the Apex II is a faster turning kite that the same size Apex III, yet the III is also larger in overall size (say 8m III vs a 7.5m II) which gives it a slightly better bottom end, the extra bridle and pulley which looks like it was borrowed from the Montana IV makes the larger kite turn more like the smaller counterpart, but not quite.

tridude - 13-8-2012 at 12:14 PM

Quote:
Originally posted by B-Roc
Anyone other than me wonder why lower aspect kites like the Apex and Access use one or two pulleys in their mixer and higher aspect kites like the Montana, Frenzy, Eskimo, use 2 or 3 pulleys?

I know more pulleys can decrease bar pressure and I know on kites like the Outlaw they used the pulleys to change the camber as well as the AoA of the kite.

So my question is... do you think the lower aspect kites use less pulleys to decrease the cost of the kite or allow for heavier bar pressure or just because they are simpler kites?

I've often wondered how a kite maker decides what type of speed system they will use and why some go with 1, 2 or 3 pulleys.

Anyone ever tried adding a 3rd pulley to a 2 pulley mixer or a 2nd pulley to a 1 pulley mixer? Think it could be done without a major reconfig of the bridle based on the premade lengths of the bridle legs?


B,

If I not mistaken the FSer 1.5 mod adds a third pulley.................my understanding it gives you more depow but suffers a tad bit on the bottom end........the FSer P4 speed system tweeks camber as well as AOA and is the only sail out there that does this...Powerzone would know for sure.... hey I can still talk some foil smack...........lol

BeamerBob - 13-8-2012 at 12:24 PM

I think the Montana changes camber and AOA when you sheet in.

tridude - 13-8-2012 at 12:32 PM

copy katz........................lol well then I stand corrected. Is the M a 3 pulley mixer as well?

Bladerunner - 13-8-2012 at 04:32 PM

Pretty sure Conceptair was doing camber adjustment since it came out with the Smart kite ?

krumly - 17-8-2012 at 01:47 PM

Adding pulleys and changing the way pulleys are set up allows for refinements in chordwise camber and profile adjustment. The simple single pulley bridle takes in about 50% at the center of the kite of whatever you pull in at the trailing edge. With that setup, you usually see the B & C bridle rows ganged up on the pulley. Cruder and coarser than a more complex set-up, but cheaper and maybe just fine depending on kite size or design. Low AR kites have a much broader range of angle of attack than high AR kites, and a deeper foil section is usually more tolerant of imprecise shaping. Old Ozone Access' used a single pulley setup. They switched to dual pulley like the Frenzy a few years back.

The chordwise attachment location of a bridle row will aslo affect the shaping. If you have a single pulley setup with a B row close to the nose, that will change the profile differently than if that B row is furhter totward the trailing edge.

A typical 2 pulley mixer will take in about 50% at the rear pulley of what you take in at the trailing edge pulley and about 25% at the front pulley (1:2 and 1:4). The front row/nose stays fixed (0%).

krumly