String Tension and temperature change

Discussion in 'Badminton Stringing Techniques & Tools' started by BaddGolfer, Dec 25, 2006.

  1. BaddGolfer

    BaddGolfer Regular Member

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    Cooler, Thats one of the things that bugged me as well for a while. I think the pressure listed by the weather reports is not the absolute pressure at a particular location, but one that is "reduced" to mean sea level... Atleast thats what I understand from this ...

    "Mean sea level pressure (MSLP or QFF) is the pressure at sea level or (when measured at a given elevation on land) the station pressure reduced to sea level assuming an isothermal layer at the station temperature.

    This is the pressure normally given in weather reports on radio, television, and newspapers. When barometers in the home are set to match the local weather reports, they measure pressure reduced to sea level, not the actual local atmospheric pressure. See Altimeter (barometer vs. absolute).

    The reduction to sea level means that the normal range of fluctuations in pressure is the same for everyone. The pressures which are considered high pressure or low pressure do not depend on geographical location. This makes isobars on a weather map meaningful and useful tools."



    http://en.wikipedia.org/wiki/Atmospheric_pressure

    The same report is saying the pressure at an altitude of 5486m is 1/2 of 1 Atmosphere. You can guess what the absolute pressure will be in Calgary which is I think is around 1000m elevation.
     
    #41 BaddGolfer, Dec 26, 2006
    Last edited: Dec 26, 2006
  2. DinkAlot

    DinkAlot dcbadminton
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    What duh?! :eek: NGP doesn't like beer, he prefers Hong Kong Milk Tea...with his Cab 20 Tour and MP string at 75F. :D :D
     
  3. DinkAlot

    DinkAlot dcbadminton
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    Woo-Hoo! It's much nicer in Los Angeles :D :

    And we use 77 speed shuttles for the most part.

    Current conditions as of 2:47 pm PST: Fair
    Temp: 72°
    Feels Like: 72°
    High: 72°
    Low: 50°
    Barometer: 30.06 in and falling
    Humidity: 25%
    Visibility: 8 miles
    Dewpoint:34°
    Wind: Calm
    Sunrise: 6:57 am
    Sunset: 4:50 pm

     
  4. Pete LSD

    Pete LSD Regular Member

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    I don't understand too. That is so weird.
     
  5. cooler

    cooler Regular Member

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    AH I SEE. Thanks, u solved this riddle of mine which had bugged me for a long while. This barometric thingy (not metric at all) is meant for weatherman making their little isobar map. It is a calculated number , NOT MEASURED.

    "imagine if each stations bored a hole straight down to sea level, lowered their pressure sensing device to the bottom of the hole, and obtained readings. This is the sea level barometer."

    so, reading barometric pressure has less meaning to me now. It explains why before i keep seeing vancouver and calgary pressure are so similar, and often calgary barometric pressure is even higher than vancouver but yet van. is at sea level. The confusing part weather report listed them as 'Pressure', and not barometric pressure. Barometric pressure is quite useless for the average joe public.
     
    #45 cooler, Dec 26, 2006
    Last edited: Dec 26, 2006
  6. taneepak

    taneepak Regular Member

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    Discounting altitude and humidity the lower the ambient temperature the more dense the air (also more oxygen). The lower the shuttle rating number the slower or lighter the shuttle. That is why a 76 or 77 shuttle is suitable for Malaysia, Thailand, Indonesia, but not suitable for say Sweden in winter. In hot countries, where the air is less dense a lower rating or slower shuttle, like 76, is suitable because the less dense air allows the shuttle to travel through the air faster than would be the case in Sweden in winter.
    To overcome the more dense air in cold countries, you need a higher rating, which also means a heavier, shuttle to push through the denser air.
    Matt has the air density in cold/hot countries the wrong way round. If shuttle manufacturers were to distribute the different ratings of shuttles according to his air density/shuttle rating, they will be out of business.
    This is why all land speed records for cars are always held in hot locations. You need the less dense air, which far outweighs the more oxygen advantage of denser air in cold locations, to propel the car faster. The shuttles rating system works on the same principle.
     
  7. taneepak

    taneepak Regular Member

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    Discounting altitude and humidity the lower the ambient temperature the more dense the air (also more oxygen). The lower the shuttle rating number the slower or lighter the shuttle. That is why a 76 or 77 shuttle is suitable for Malaysia, Thailand, Indonesia, but not suitable for say Sweden in winter. In hot countries, where the air is less dense a lower rating or slower shuttle, like 76, is suitable because the less dense air allows the shuttle to travel through the air faster than would be the case in Sweden in winter.
    To overcome the more dense air in cold countries, you need a higher rating, which also means a heavier, shuttle to push through the denser air.
    Matt has the air density in cold/hot countries the wrong way round. If shuttle manufacturers were to distribute the different ratings of shuttles according to his air density/shuttle rating, they will be out of business.
    This is why all land speed records for cars are always held in hot locations. You need the less dense air, which far outweighs the more oxygen advantage of denser air in cold locations, to propel the car faster. The shuttles rating system works on the same principle.
     
  8. taneepak

    taneepak Regular Member

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    Discounting altitude and humidity the lower the ambient temperature the more dense the air (also more oxygen). The lower the shuttle rating number the slower or lighter the shuttle. That is why a 76 or 77 shuttle is suitable for Malaysia, Thailand, Indonesia, but not suitable for say Sweden in winter. In hot countries, where the air is less dense a lower rating or slower shuttle, like 76, is suitable because the less dense air allows the shuttle to travel through the air faster than would be the case in Sweden in winter.
    To overcome the more dense air in cold countries, you need a higher rating, which also means a heavier, shuttle to push through the denser air.
    Matt has the air density in cold/hot countries the wrong way round. If shuttle manufacturers were to distribute the different ratings of shuttles according to his air density/shuttle rating, they will be out of business.
    This is why all land speed records for cars are always held in hot locations. You need the less dense air, which far outweighs the more oxygen advantage of denser air in cold locations, to propel the car faster. The shuttles rating system works on the same principle.
     
  9. Matt

    Matt Regular Member

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    lol tanepeak, you had to post it 3 times?

    As I said it's not mine my rating system.

    I still have not gotten an explaination why speed 78 flies noticably slower in warm air at the temp when the facility raised up the temperature, then compared to when it's at the normal cooler temperature when it does fly at the proper speed. That's pretty much the piece I'm most interested in. This is because is a counter example where the proper rating system does not explain.

    I also think of it in F1 perspective. More down force the car has, the slower the car would be because there is more weight generated, with increased drag which results in a lower top speed. With less down force, the car will be faster because of less weight generation and it can obtain a higher top speed.
     
    #49 Matt, Dec 26, 2006
    Last edited: Dec 26, 2006
  10. taneepak

    taneepak Regular Member

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    Discounting altitude and humidity the lower the ambient temperature the more dense the air (also more oxygen). The lower the shuttle rating number the slower or lighter the shuttle. That is why a 76 or 77 shuttle is suitable for Malaysia, Thailand, Indonesia, but not suitable for say Sweden in winter. In hot countries, where the air is less dense a lower rating or slower shuttle, like 76, is suitable because the less dense air allows the shuttle to travel through the air faster than would be the case in Sweden in winter.
    To overcome the more dense air in cold countries, you need a higher rating, which also means a heavier, shuttle to push through the denser air.
    Matt has the air density in cold/hot countries the wrong way round. If shuttle manufacturers were to distribute the different ratings of shuttles according to his air density/shuttle rating, they will be out of business.
    This is why all land speed records for cars are always held in hot locations. You need the less dense air, which far outweighs the more oxygen advantage of denser air in cold locations, to propel the car faster. The shuttles rating system works on the same principle.
     
  11. Matt

    Matt Regular Member

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    Spam! postings from tanepak!
     
  12. DinkAlot

    DinkAlot dcbadminton
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    LOL! What's this world coming to? Who would have thought Eepak spamming. :p :D :D
     
  13. Matt

    Matt Regular Member

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    Yeah beats me. Either taneepak got internet issues about his post not showing up on his or was intentionally doing it. In either case, the moderators would not like to see that kind of action on the forum as it goes against the rules for spamming.
     
  14. DinkAlot

    DinkAlot dcbadminton
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    Matt: take it easy, I'm just joking. :p Eepak wouldn't knowingly post all those times. Even if he did, we should just leave it up to the Mods, not a big deal. :)
     
  15. BaddGolfer

    BaddGolfer Regular Member

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    Matt, if you are talking about the same shuttle behaving that way, then please note the two temps and humidity readings. Theoretically its possible, when the heater is turned on to raise the gym temp, the humidity went down and dry air is more dense than humid air. I am not sure if the change in humidity is so much to more than offset the temp increase. I never played in a heated gym, so I have no first hand experience on this...
     
  16. BaddGolfer

    BaddGolfer Regular Member

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    The next thing for you to figure out is the effect of the difference in gravity at high altitude locations! :p:D
     
  17. Matt

    Matt Regular Member

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    Yes, this is assuming the same shuttle. Maybe you can ask the facility where you play to raise the temperature up for a while then turn it off as a test. Then the shuttle out, you may notice what I was observing.
     
  18. BaddGolfer

    BaddGolfer Regular Member

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    I don't think my facility has heating :crying: (atleast I've never seen them use it). Many times in winter, I don't even take off the warmups...
     
  19. taneepak

    taneepak Regular Member

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    Sorry about the multiple posts due to one of two trans-Pacific cables being damaged by Taiwan earthquake. All internet communications in this part of the world adversely affected.
     
  20. DinkAlot

    DinkAlot dcbadminton
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    This is true, as of right now, all these websites are down:

    www.puppysports.com
    http://www.bbesports.com/

    :(
     

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