Flexifoil stack and power

Flexifoil stack and power

Post by Chris Hi » Tue, 28 Jun 1994 18:34:03


Thanks for the net.wisdom, generated from my last post regarding
my observation that the pull generated by a single flexi I was
flying being more than doubled when a second was stacked.

As I was flying in a fairly low wind I can only suggest that putting
the second flexi in the stack caused the speed of the whole to increase
and thus increased the total power, hence my observation.

--

   Mr Paranoid sends me messages, he says that THEY have taken over
   my employers; I fool them by disseminating my own opinions!

 
 
 

Flexifoil stack and power

Post by Andy Ta » Sat, 02 Jul 1994 18:45:32

Quote:


>Subject: Flexifoil stack and power
>Date: 27 Jun 1994 09:34:03 GMT
>Thanks for the net.wisdom, generated from my last post regarding
>my observation that the pull generated by a single flexi I was
>flying being more than doubled when a second was stacked.
>As I was flying in a fairly low wind I can only suggest that putting
>the second flexi in the stack caused the speed of the whole to increase
>and thus increased the total power, hence my observation.
>--

>   Mr Paranoid sends me messages, he says that THEY have taken over
>   my employers; I fool them by disseminating my own opinions!

Similar things in the boating world.  The foresail or jib increases the
speed of flow of air over the rear of the main sail and hence its lift.

So maybe the second flexi has simialar effects.

Andy....

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Flexifoil stack and power

Post by David Lo » Fri, 08 Jul 1994 06:54:32


My experience with flexifoil stacks is that with two you get less than
double the pull you got with one. And with each one you add you lose
some more. The per kite pull with two is greater than the per kite pull
with three. The greater the separation between the kites the less loss.
When stacked each kite creates some turbulence for its neighbor and
causes this loss in pull. Allthough I have not made measurements I am
reasonably sure that the more kites you put in a stack the slower the
group flys. Since getting a buggy I have a renewed interest in flexi
stacks and maybe I can get around to making some measurements. BTW it is
fun to fly one or more flexi's in front of two line deltas. It works
best on kites that have the bridle points far apart such as a TOL Team
kite or a 10 ft size delta. I have added a single flexi in front of a
Quadrifoil 25 to pull a buggy and it works pretty good. Do not try more
than one though, because as you launch a stack of flexi's they do a lot
of bucking before they lock in and they invariably tangle in the lower
lines of the Quadrifoil.
                            Dave Lord