5. Comparison of Flowforms

From all flowforms I know, I took specified datas for comparison. I scaled the main profile and the main flare to a specific length of the base line of the profile. All measures are related in percent to this base line.

Description:
1. Base line of the profile without front opening (always 100 percent).
2. Maximum height of profile.
3. Distance of maximum height to leading edge.
4. Height of front opening.
5. Angle of front opening to base line.
6. Distance of drag point to leading edge.
7. Angle of drag point to base line.
8. Angle of trailing edge.
   (In curved profile at about 20 percent of base line)

These flowforms I used for the comparison with the given abbreviations. I heard about other flowforms and similar kites, but I have no information about them for comparison.

5.1 Information from sketches for comparison

After I made sketches with the same relationship I took the information for comparison from the sketches into the following tabel. These information were already published in the first edition and will not be used in further examinations.

Remarks:
1. The outer profile is used for main profile.
2. The upper surface between maximum profile height and trailing edge is made like on other flowforms by Jim Rowlands.
3. The center profile is used for main profile.
4. Information are reproduced with given datas of the sketch.
5. Information are reproduced with the relationship in sketch.
6. These information are measured on the kite and reproduced with a sketch.

5.2 Calculated information for comparison

To get more exact information about the flowforms I calculated the datas for the comparison with the given information of the building plans. Against the first edition I used everytime the outer profiles and the outer keels for the comparison.

Anmerkungen:
1. These information are measured on the kite and reproduced with a sketch.
2. Information are reproduced with given datas of the sketch.
3. Information are reproduced with the relationship in sketch.

5.3 Categories of flowforms

After making sketches from all known flowforms in a relative size, I could compare all flowforms together. The flowforms can be aranged in three categories. Some flowforms have details from more than one kategory.

Flowforms based on Jim Rowlands
Flowforms from Jim Rowlands have a large profile height, a straight course of profile to the trailing edge and a keel, which leading edge has not an angle of 90 degrees. The distance of maximum height of profile to the leading edge is larger. In stronger wind there can be too much lift and the angle of attack may be too low. The flowforms with bridle in one row can collapse by pressing down the top side of the inlet opening. With a bridle in 2 rows the angle of attack can be changed to reduce the lift in higher wind. On my own, I had until now no problems with collapsing by closing the inlet opening.

Sutton Flowforms
This named flowforms are all made out of 4 chambers and 3 keels. The course of profile on the top side is curved from leading edge to trailing edge. The maximum height is placed nearer to the leading edge. The leading edge of the keels have an angle of 90 degrees and have a bridle in one row. With a lift more to the leading edge the angle of attack can not increase too high and the kite will fly stable even if there is more wind.

In some plans the maximum height is too large and set to far from the leading edge. In gusty wind some built flowforms flew unstable and collapsed.

Flowforms with curved trailing edge
The curved trailing edge is made by different profiles or by changed course of profiles to the trailing edge. Most times the outer profiles are longer as the inner profiles. Depending on the normal size of profile the distance of maximum height to the leading edge is larger and will cause more lift for the longer profiles.

If all profiles have the normal size the aspect ratio would be larger than one. That may be a reason for a powerful lifter with longer profiles for stability.

Remarks
1. Only on flowforms with a bridle in two rows is a change of the angle of attack possible. On all other flowforms a change is not posible.
2. If there is a large lift depending on construction far from the leading edge the kite will fly unstable in high wind speed and may collapse.

5.4 Profiles compared with wings for air planes

The base for this examination are the information I found about profiles for air planes. On those profiles the position of maximum profile height is most times at 30 percent of the profile length. On the profiles of the flowform I used the distance between position of maximum profile height and trailing edge for 70 percent of the profile length. With these information I calculated the theoretical complete profile length and the related profile height. I used the calculated datas of flowforms for the examination.

1. Given profile length from upper leading edge to the trailing edge.
2. Distance between position maximum profile height and trailing edge
3. Calculated complete profil length with 70 percent between position of maximum profil height and trailing edge.
4. Difference between calculated and given complete profile length.
5. Calculated profile height related to the calculated complete profile length.

Remarks:
1. With negative values for the difference between calculated and given complete profile length a standard profile could not be used for construction.
2. With values about zero for the difference between calculated and given complete profile length a standard profile could be used for construction with changes on the top surface between position of maximum profile height and leading edge.
3. With positive values for the difference between calculated and given complete profile length a truncated standard profile could be used for construction.
4. A remarkable point with possible truncated standard profiles for construction is the maximum profil height of less the 20 percent of the complete profile length.

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