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Author Topic: Speed formula  (Read 3531 times)

Jim Roselle

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Speed formula
« on: April 03, 2015, 05:53:46 AM »
Hey guys I need your help. What's the formula for calculating speed? I need to input line length, laps, and time and come out with a speed.

Thank you,

Jim
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Offline Bob Heywood

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Re: Speed formula
« Reply #1 on: April 03, 2015, 07:30:09 AM »
The following is taken from AMA Competition Regulations for C/L Speed:

12. Scoring of flights: The best official flight by each competitor in an event, in terms of miles per hour, shall be used for competition and record scoring.

12.1 To separate the competitors in the case of a tie, the average of the competitor’s two (2) best flights will be taken. In the case of the two (2) best flights still producing a tie, the average of the three (3) best flights will be taken to determine the winner.

12.2 To compute the speed in miles per hour for ½ A Speed, use the formula: MPH = 1016.79 / time in seconds.

12.3 To compute the speed in miles per hour for A Speed, use the formula: MPH = 1670.76 / time in seconds.

12.4 To compute the speed in miles per hour for ½ A Proto Speed,.21 Sport Speed, B Speed, D Speed and Jet Speed use the formula: MPH = 1799.28 / time in seconds.

12.5 To compute the speed in miles per hour for 21 Proto Speed and Formula 40 Speed use the formula: MPH = 3598.56 / time in seconds.

12.6 When manual timing is used, the time for calculation of speed shall be determined as follows: The times from three watches shall be totaled. The total of the watches will be divided by three. All results will be truncated to three decimal places.

12.7 If using manual timing, records shall be recognized only when no more than .12 second variation exists between any of the three (3) watches. If the watches do not read within this required tolerance, and a record has been broken, the flier may request another attempt permitted. In the case when no record is broken, or if the flier does not elect to take another attempt, the average of the two (2) watches that are within .12 second of each other shall be taken for scoring purposes, disregarding the results of the third watch. If no two (2) of three (3) watches are within .12 second of each other the flier has the right to ask for another attempt, with the previous flight being cancelled, or to request that the average of the three (3) watches be used for scoring.

You will want to use Para 12.4 for line lengths that are timed for a nominal 1/2 mile. That includes 52.5 ft / 8 laps, 60 ft / 7 laps, and 70 ft / 6 laps.
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Offline Bob Heywood

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Re: Speed formula
« Reply #2 on: April 03, 2015, 08:00:03 AM »
The full derivation is:

(2 x Line Length(ft) x #Laps x 3.14159 / time (sec)) x (3600 (sec/hr) / 5280 (ft/mi))
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Offline BillLee

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Re: Speed formula
« Reply #3 on: April 03, 2015, 08:52:29 AM »
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Jim Roselle

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Re: Speed formula
« Reply #4 on: April 03, 2015, 09:23:59 AM »
Quote from: Bob Heywood on April 03, 2015, 08:00:03 AM
The full derivation is:

(2 x Line Length(ft) x #Laps x 3.14159 / time (sec)) x (3600 (sec/hr) / 5280 (ft/mi))

Thanks!
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Jim Roselle

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Re: Speed formula
« Reply #5 on: April 03, 2015, 05:06:50 PM »
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Offline Paul Smith

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Re: Speed formula
« Reply #6 on: April 04, 2015, 07:04:05 AM »
Or the more simple and commonly-used formulae:

3600 divided by the one mile time.
1800 divided by the half mile time.
3600 divided by the one kilometer time.

Admittedly, my formulae are inaccurate by a factor of 0.0395%.

A one inch difference in a 60' set of lines is .139%.

The Rule Book formula is required for speed contests, but the simple way is fine for everyday use.



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Paul Smith

Offline don Burke

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Re: Speed formula
« Reply #7 on: April 04, 2015, 11:09:35 AM »
Quote from: Paul Smith on April 04, 2015, 07:04:05 AM
Or the more simple and commonly-used formulae:

3600 divided by the one mile time.
1800 divided by the half mile time.
3600 divided by the one kilometer time.

Admittedly, my formulae are inaccurate by a factor of 0.0395%.

A one inch difference in a 60' set of lines is .139%.

The Rule Book formula is required for speed contests, but the simple way is fine for everyday use.




I use the my stop watch time for estimates knowing that 1/2 mile at 120 mph = 15 sec.  This for when at the circle and not having a computer hanging around my neck.
« Last Edit: April 05, 2015, 02:44:33 PM by don Burke »
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Offline Tim Wescott

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Re: Speed formula
« Reply #8 on: April 04, 2015, 03:14:16 PM »
Quote from: Paul Smith on April 04, 2015, 07:04:05 AM
3600 divided by the one kilometer time.

If you want the answer in km/hr.
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Offline Paul Smith

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Re: Speed formula
« Reply #9 on: April 04, 2015, 08:02:03 PM »
Of course.  Those of who live on the border line need to be fluent in both English & French measurement. 
Parly vous metric?

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Offline BillLee

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Re: Speed formula
« Reply #10 on: April 04, 2015, 08:11:29 PM »
Or use the program mentioned earlier on the NCLRA website and ask it for km/hr
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Bill Lee
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