Re: spark length vs. power input

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Jim Lux by way of Terry Fritz <teslalist-at-qwest-dot-net>" <jimlux-at-earthlink-dot-net>

At 08:36 AM 6/9/2003 -0600, you wrote:
>Original poster: "by way of Terry Fritz <teslalist-at-qwest-dot-net>" 
><Mddeming-at-aol-dot-com>
>
>In a message dated 6/8/03 11:47:24 PM Eastern Daylight Time, 
>tesla-at-pupman-dot-com writes:
>
>
>
>>And for foreign countries:
>>
>>      d = (k' * sqr p) * 2.54 cm./in. and is reduced to d = 2.54 * (k' * sqr
>>p)
>>
>>      where:  d = spark length in centimeters
>>
>>                    k' = correction factor as noted above
>>
>>                    p = input power in inches
>
>
>
>1) What's a "foreign country" depends on who is reading your mail. By 
>"foreign country" I assume you mean the entire world except for the US and 
>Liberia, these being the only places still using inch measurements.  IMO, 
>when sending email worldwide, it is usually best to avoid ethnocentric 
>terms such as "foreign" and "alien". Note: Most US scientists "went 
>metric" over 40 years ago, although US engineers did not. (this was the 
>basis of the last Mars Lander disaster)

Ahem... US engineers, at least the ones like me working at Jet Propulsion 
Lab, actually use metric units.. The units problem wasn't with a Mars 
Lander, but with the Mars Climate Orbiter (both launched the same year), 
and was the manufacturer (Lockheed-Martin) supplying thrust data in pounds, 
instead of newtons.  The interface control drawing, which defines how the 
data is to be passed, said newtons.  The practical problem was that there 
wasn't any independent cross check. The thrusts were so small that the 
uncertainty in the observed trajectory changes was large enough that the 
measurements were consistent with the (incorrect) data supplied by LM.

The lander problem was most likely software thinking that the lander had 
touched down (even though it hadn't) and cutting off the engines early.


For that matter, many countries still use "customary unit" hardware (i.e. 
things like 6-32 screws, and we won't even get into things like Whitworth 
threads). Last summer, at least, I bought things like candy and vegetables 
by the pound in England.  I understand, though, that there is a legislative 
move afoot to require shopkeepers to post prices per kg, and to conduct 
transactions in metric units.  In some industries, the "stone" is still 
used for weight and the "hand" for height.

I was amused (and pleased) to see "Low Joule" Coke in Australia a few years 
ago.


>2) I don't think you really meant     " p = input power in inches"
>
>Matt D.