Quadline Kite Line Length Stretch Estimator v0.1.1

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1	Quadline Kite Line Length Stretch Estimator
2	Author: Philip Chase <philipbchase@gmail.com>
3	Version: 0.1.1
4	This tool is designed to help kite fliers estimate the elongation of flying lines under normal flying conditions. The calculations estimate not only total stretch, but the trend of stretching as load increases.
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6	To use this tool, signin to Google Drive and make a copy from the file menu. With the editable copy, adjust the white input fields in the Metric column of your duplicate sheet. All gray fields are calculated values. You can also download as an Excel file.
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8	Note: The estimate for "% of load on bottom line" is dependent on kite and flying style. Consider this variable carefully when estimating line stretch and especially relative line stretch. This value needs to reflect the bottom line load under high load, high speed conditions. I assert that those are the conditions where any potential benefits or liabilities of line stretch will be maximized.
9	Note: "Kite pull / pilot mass (kg or lb)" is also a subjective measure but has no effect on the ration of relative stretch. Similarly, line length has no effect on the ratio of relative stretch.
10	Note: The use of Dyneema lines is not meant as an endorsement. They were used in these calculations because Eurocord published a useful dataset that allowed these calculations to be made with more precision and fewer assumptions. Many thanks to Eurocord for publishing this data.
11	Note: I used 50kg for the kite pull because Andrew Beattie believes that 50kg was Peter Lynn's estimate of kite load under normal buggy conditions. This has not yet been verified. It seems completely reasonable to me. That said, the true number is probably a percentage of the pilot's weight or perhaps the combined weight of pilot and vehicle. So shoot me.
12		Lineset Number 1		Lineset Number 2
13	Line Properties	Metric	Imperial	Metric	Imperial
14	Top line	DS-110	DS-110	DHPT-190	DHPT-190
15	Elongation (%)	2.2	2.2	2.0	2.0
16	Minimum breaking strength (daN or lbf)	110	248	190	428
17	Effective breaking strength (daN or lbf)	125	281	200	450
18	Bottom Line	DS-55	DS-55	DHPT-190	DHPT-190
19	Elongation (%)	2.8	2.8	2.0	2.0
20	Minimum breaking strength (daN or lbf)	55	124	190	428
21	Effective breaking strength (daN or lbf)	62	140	200	450
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23	Lengths and expected loads
24	Line length (m or ft)	22.9	75.1	22.9	75.1
25	Kite pull / pilot mass (kg or lb)	50.0	111	50.0	111
26	% of load on bottom line	30%	30%	30%	30%
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28	Calculated Values
29	Ratio of bottom line load to top line load	0.43	0.43	0.43	0.43
30	Top line elongation/daN	0.0173	0.02	0.0100	0.01
31	Bottom line elongation/daN	0.0452	0.05	0.0100	0.01
32	Ratio of top line to bottom line stretch at equal load	0.38	0.38	1.00	1.00
33	Ratio of top line to bottom line stretch with distributed load	0.89	0.89	2.33	2.33	<--- A number less than 1 means the bottom line will stretch more than the top under load
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35	Front line load (daN or lbf)	35	79	35	79	28%	% of effective breaking strength
36	Back line load (daN or lbf)	15	34	15	34	24%	% of effective breaking strength
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38	Front line elongation (cm or ft)	6.9	0.23	4.0	0.13
39	Back line elongation (cm or ft)	8.7	0.29	1.8	0.06
40	Front minus back elongation (cm or ft)	-1.8	-0.060	2.2	0.072	<--- A negative number means the bottom lines will stretch more than the top lines under load
41	Front minus back elongation (cm or in)	-1.8	-0.72	2.2	0.87
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