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Author Topic: SUL flying in cold air is more floaty than in warm air  (Read 1114 times)
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rudyy
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« on: August 25, 2013, 05:34 PM »

I have been having a lot of flight time with my Fearless Tattoo under almost no wind condition.   Somehow, I discover a very interesting thing.  If I fly in the evening time when the temperature drops, the Tattoo is very floaty in the air.  With about the same wind condition but in a hot sunny day, the Tattoo is a lot less floaty.  It maybe that the cold air is more dense which gets the kite more push when I pull the lines.    I discover this when I start feeling I need a lot more footwork to get the kite staying in the air in the hot sunny day than in the cold evening.
« Last Edit: August 26, 2013, 05:23 AM by rudyy » Logged
Krijn
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« Reply #1 on: August 25, 2013, 11:43 PM »

(i am an inland-flyer)

i always prefer the winds in okt-march


Krijn
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SkyRags
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« Reply #2 on: August 26, 2013, 01:06 AM »

Dam

I was looking forward to summer Tongue
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lasapcheong
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« Reply #3 on: August 26, 2013, 01:42 AM »

This looks like the truth from my own experiences. For the first few years I flew in the San Francisco Bay Area. After coming back to Singapore and flying in 80 - 90 degree temps with 80 - 90% humidity, my SUL kites seemed heavier for some reason.

-Darryl
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RobB
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« Reply #4 on: August 26, 2013, 04:55 AM »

I would agree... my evidence, same kite, one video shot in the winter cold, the other in the summer heat. Pretty much the same wind, even the same wind direction...

Winter...
Snow Devil... Feb.2013


Summer...
https://vimeo.com/69441474


The kite seems to take more work to keep it flying in the summer.
Well, kite season is only two weeks away ! So glad the summer is over !
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vigli
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« Reply #5 on: August 26, 2013, 05:48 AM »

Rob.... very nice flying.... Thanks for video
We have same pure white SD SUL.
 Wink
Very nice and clean white  look next to black LE, TE, spars and other black parts of the kite.
best boris
« Last Edit: August 26, 2013, 05:50 AM by vigli » Logged
ae
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« Reply #6 on: August 26, 2013, 07:37 AM »

Colder air is denser, as it more moist air. You can feel the effect very clearly in the sul and below range.
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Wayner
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« Reply #7 on: August 26, 2013, 12:06 PM »

Big penalty flying SULs here in the Mohave desert during the summer. 100+ reduced lift and no breeze to cool you off.  Sad
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sluggo
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« Reply #8 on: August 26, 2013, 12:44 PM »

Colder air is denser, as it more moist air. You can feel the effect very clearly in the sul and below range.


Actually, dry air is denser than moist air.
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tpatter
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« Reply #9 on: August 26, 2013, 01:04 PM »

I don't know about the physics of this, but I do know that, physically, I notice having to drag my kite around the sky much less when it is cooler.
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6 kite tom
Ca Ike
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« Reply #10 on: August 26, 2013, 09:14 PM »

You will also notice that it takes more work in the same conditions on a hot day if the grass was watered that morning or not. The hot "steam thermals" off the grass make it harder to fly because water vapor causes a lot of drag and in a sense weighs the kite down. Same reason flying in fog is tough.
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tpatter
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« Reply #11 on: August 26, 2013, 09:21 PM »

I'm going to call physicality again and say that, since the kite is wet (from the watering and associated moisture from contact with the ground) that the additional weight makes is less able to 'fly'. 

Trust me guys, I really do want to believe that John Weldon's kite just floats around because he is flyng it here in the misty mountain regions of the PNW, but I'm sure not sure I buy it. 

I'm waiting for JC, otherwise known as John Chilese to chime in here - that's an engineer that I put some faith behind. 
« Last Edit: August 26, 2013, 09:28 PM by tpatter » Logged

6 kite tom
KaoS
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« Reply #12 on: August 27, 2013, 01:59 AM »

...  since the kite is wet (from the watering and associated moisture from contact with the ground) that the additional weight makes is less able to 'fly'. 


In the case of SULs, maybe. 

But with standard weight nylon kites, the moisture is absorbed by the fabric dramatically reducing the porosity.  In light winds, the increase in sail efficiency far outweighs (excuse the pun) the weight penalty incurred, so the kite is easier to keep flying.

Don't believe me?  On a light wind day at the beach allow your Carrington Midi Sandpiper to go for a swim then fly it dry.

(Now where's my beer and popcorn?  Grin )
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Kevin Sanders

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rudyy
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« Reply #13 on: August 27, 2013, 06:57 AM »

Now it makes me wonder how floaty the difference is between flying a SUL at the top of the mountain and at the valley under the same wind condition and temperature.  Air is less dense higher up, and so logically, it will be less floaty at the top of the mountain.
« Last Edit: August 27, 2013, 06:59 AM by rudyy » Logged
Steve
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« Reply #14 on: August 27, 2013, 09:40 AM »

I have flown at 8300 ft.
not a lot of 'float' at that altitude.
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Steve ... Ancient One
-look to the sky with imagination, grasp the wind with outstretched arms and take flight
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