Harald Prinzler
Mikroelektronik, Fesseldrachen und Fotografie
Detmolder Straße 93
D-33175 Bad Lippspringe
Phone: +49-5252-7830
email: harald@hprinzler.de
URL: http://www.hprinzler.de

Questions and information (Kites)

Some people asked me about some problems or for special information. Here I will try to give answers, if I have no web file for that theme.

Flying line for 6m Delta?

A Delta is not the best kite for lifting power. The advantage is the flying in low wind speed. I use a 3mm Polyamid line and I think it is to thick. The 2mm Polyamid line will always be enough. If I use a line loop for KAP, I take the 1.5mm Polyamid line.

Flying line for Flowform #16?

I have no Flowform #16. The size of it is like the Flowform from Jim Rowlands. For that kite it is enough to take the 3mm Polyamid line (150daN). Because of the one level of bridle lines on the flowform #16, I guess a 2mm Polyamid line (about 90daN) will be enough. Even the bigger Flowform (50 sq.ft.) I fly always with the 3mm Polyamid line.

Questions about soft kites (especially flowforms)

How do you calculate the length of bridle lines?

For length of the center bridle line I take 2.5 times the largest distance between bridle points on the kite. For the other bridle lines I use the formular of pythagoras to calculate the line length.
On small kites it is possible to use the same length for all bridle lines. Even with the calculated different length of bridle lines the kite is not real flat rigged. For real flat rigging the height of the keels should be used in the calculation.

Why do large kites work better than small kites?

Errors by building the kites are smaller in relation to the larger size. So you can build a large kite more exactly as a smaller kite.
Large kites are not so critical in gusty winds, because they only react slow on wind changes. Small kites react much faster and tend easier to unstable flight.

How difficult is making large kites?

It is not harder to make a larger kite. You have only to handle with more fabric. Sewing the top side of large soft kites is easier, because it is not so curved as on small kites.
The same errors on building kites are smaller in relation to the larger size. So you can build a large kite more exactly as a smaller kite.
Take care, large kites are more sensitive to pressure by wind speed as small kites. A large kite will break earlier than a small kite.

How do the holes on flowforms work?

Usually the the biggest holes on bottom surface are near to the leading edge and on top side near the trailing edge. With more wind the air flow increases (bottom side in and top side out) and the trailing edge of the flowform will not rise anymore. It works against the rising possibilty of the profile form. The jet chute (opening in trailing edge) stabilizes the direction by air flow through the kite.

Are the holes on top and bottom surface really nescessary?

With the holes on bottom and top surface the wind range for a stable flight is increased. Of course it works without those holes, too. But then on higher wind speed the kite is earlier unstable.
I made experiences on my second flowform. I added the holes on top and bottom surface half a year later I finished the kite. Without the holes the kite was only useful for light wind. With the holes the wind range is larger. The holes do not affect the flying in lower wind speed.

Is it possible to scale soft kites?

With scaling soft kites there is a change of lift power depending of the profile form, too. I think an upscaled soft kite will fly at a higher angle, because the profile form makes too much lift. Therefore I reduced the maximum height of my newest flowform design for larger kites.
Take care, large kites are more sensitive to pressure by wind speed as small kites. A large kite will break earlier than a small kite.
An upscaled soft kite from a given design is more to use in lower wind range as the kite in original size. This depends on the increased lift of the top surface on the upscaled kite.

Isn't it better to use a two row bridle on flowforms?

A two row bridle is only needed, if the maximum profile height is oriented more to the middle of the chord. With the maximum profile height at about 15 percent of the base line it is in my opinion not necessary.

How to make a compound bridle?

In a compound bridle the lines of each bridle row (primary lines) are leaded to one ring. From these rings I lead another line to the ring were the flying line is fixed (secondary lines). With changes on the secondary lines it is possible to change the angle of attack of the kite.
At first fly the kite only with tension on front bridle row. With a tail you can first slow down the unstable flight of the kite. Now shorten the secondary lines of the other bridle rows to get the kite more stable. Then let the tail away and check flying again.
This bridle system I use for all kites I have made with more than one bridle rows (Rokkaku, Multiflare and Flowform). I would even use them for a cody.

Take care about sketches in books

I don't trust sketches in books and printings for building kites. It is allways better to use the given data tables. I don't know how my kite plans look on any printed paper.

Which size of flowform should I use for lifting cameras?

A mean point is the complete weight of camera and system, which will be lifted by the flowform. For a weight of about 2kg I would prefer to use a size of about 2m spanwidth and 2.5m profile base line. That is the size of my third flowform (American Flowform) which is my first choice for KAP work.

Which line strength is recommendable for the American Flowform?

In the given size with 2m span with and 2.5m profile base line I use polyamid with a diameter of 2mm (about 70daN) for the bridle line and polyamide with a diameter of 3mm (about 150daN) for the flying line. In my opinion for the bridle a polyamide line with a diameter of 1.5mm (about 50daN) is strong enough.