Flow Form enlargement

• Subject: Flow Form enlargement
• From: irving@white.toronto.edu (Irving Reid)
• Date: 6 Nov 92 15:28:54 GMT

jeffy@syrinx.umd.edu (Jeffrey C. Burka) writes:
 -- asking for suggestions on scaling up a flowform


I've had a close look at the big flowforms Art Ross from Vancouver
builds.  He has built a few in the 500-1500 square foot range, along
with smaller sizes.

The main change is to make the airfoil thinner and move the high point
forward.  There's not a lot of science necessary; flowforms are
relatively forgiving about cross-section.  Guessing from only having
seen his kites, the body proportion is roughly 3-4 units span to 5 units
chord.  He also uses longer "legs" than the book plans show, partly for
stability and partly for effect.

Cell width (the spacing between ribs) doesn't scale linearly for either
flowforms or parafoils.  For 30 square feet it shouldn't be a problem,
but for larger foils you need to put the ribs proportionally closer
together to get the cross-section to keep its shape.

For 30 square feet, try a cross-section about 12% (of the chord) deep,
with the highest point maybe 10% back from the leading edge.  This is a
fairly radical departure from published plans, but then the published
plans don't fly quite as well as one would like.  At that size, it will
probably pull just on the margin of needing gloves; 300lb. line should
hold just fine, though you might want 500 in a big wind (I fly a 50sq.
foot parafoil on 500 and have never had problems).

 - irving (Hey!  I finished my Masters, Moved, and got a New Job!) -

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