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« on: April 22, 2014, 09:45:14 PM »
K K Iyer
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While watching videos of my INDORE TLG1, it occured to me that we could make an estimate of the speed at launch.
I looked at the 12 stop action pics in post no 73-75 in the following thread

http://www.rcindia.org/kites-trains-free-flight-and-all-others/for-the-5th-sweepstakes-first-model-k-k-iyer/

Educated guesses:
1. Launch height about 50 ft
2. Flight radius in launch phase about 30 ft (smaller than a control line circle)
3. Climb ends about 180 degrees after launch
4. Estimated climb time about 1 second

From the above it can be calculated that the flight path was about 112 ft till the top, in 1 second.
Since 44ft/sec is 30 mph or 48kmph, it means the launch speed was about
122 kmph!

Maybe we'll never do 1 min unless we reach 100mph/160kmph!

Comments requested from chuck glider veterans.
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« Reply #1 on: April 22, 2014, 10:00:26 PM »
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L'enfant Terrible du RCIndia



Maybe there is something to be learnt from this:



If you have reached a height of 112 feet (1344 inches) and you want the model to stay aloft for 60 seconds, then you are asking for a sink rate of 22.4 inches per second, without a thermal helping you. That shouldn't be too difficult, or am I reading you wrong?

edit: I WAS reading you wrong Wink
« Last Edit: April 22, 2014, 10:54:25 PM by VC » Logged

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« Reply #2 on: April 22, 2014, 10:33:08 PM »
K K Iyer
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Sirrrrrrr

Educated guesses:
1. Launch height about 50 ft
2. Flight radius in launch phase about 30 ft (smaller than a control line circle)
3. Climb ends about 180 degrees after launch
4. Estimated climb time about 1 second

From the above it can be calculated that the flight path was about 112 ft till the top, in 1 second.

Guessing about 2ft/sec sink (25 sec from say 50ft)
Why do you think i am paranoid about wing loading being below 3oz?
Or the balsa being under 6oz?
Who do you think invented that pivoting fuselage?

Edit: Buddenbohm's indoor models weigh about 10gms. Mine is 51!

"If you have reached a height of 112 feet (1344 inches) and you want the model to stay aloft for 60 seconds, then you are asking for a sink rate of 22.4 feet per second, without a thermal helping you. That shouldn't be too difficult, or am I reading you wrong?"

Feet/inches??
From 50ft height, need 1 ft/sec for 50 sec duration Grin
« Last Edit: April 22, 2014, 10:51:39 PM by K K Iyer » Logged
 

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« Reply #3 on: April 22, 2014, 10:55:16 PM »
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Errrrrrrrrrrrrrrrrrr- corrected Sir.


 Cheesy Giggle
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« Reply #4 on: April 22, 2014, 11:10:49 PM »
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Thanks anyway.
How many would care about TLG launch speed estimates anyway?
Maybe Saikat sir

"I'd ask him what the matter was,
But i know he don't talk...
Oh Mama, can this really be the end..."


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« Reply #5 on: April 22, 2014, 11:33:42 PM »
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Now the bricks lay on Grand Street
Where the neon madmen climb
They all fall there so perfectly
It all seems so well timed
An’ here I sit so patiently
Waiting to find out what price
You have to pay to get out of
Going through all these things twice

 Bow Bow Bow

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« Reply #6 on: April 22, 2014, 11:50:02 PM »
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Dreamt a few days back that my nylon strung 3/4 Fender was crushed during packing.
Thankfully it wasn't.

Now i lie here all so lonely
Knowing only the rate of sink
I'd ask you how to cal cu late
The coeff of lift i think...
Oh Mama...
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« Reply #7 on: April 22, 2014, 11:55:09 PM »
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Cordially inviting you to NorthEast India with RC Aunt on 24th. May. Shillong is the ONLY place in India that celebrates Dylan's birthday, since 1972, with a mega rock concert. Its Dylan all the way.
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« Reply #8 on: May 14, 2014, 02:17:08 AM »
K K Iyer
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In this age of RTFs and Quads,
Maybe someone would be interested in the article that inspired this thread:

'From Release to Stick - One Frame at a Time Using high speed video to better understand catapult glider launch dynamics
by Paul Love, San Diego, CA, USA'

https://1f9972a0-a-62cb3a1a-s-sites.googlegroups.com/site/ffqstorage/file-cabinet/FFQ35_PL.pdf?attachauth=ANoY7cq5eQmlsItN95rbPVLa0dQngcIXcAWaM8-pxyDSXdcjEwXUdirVeStTy38R829eWsWUqHzSWpha4ctOLv_zJDPCWBJmki5z9D9Q6J468Lk6rMXb3wx_vuum15MjgvnnGIx4qd1SEF-wrD14vL6YaSFdVTKEW1PW9nrZQYA9W3Hfvwa2BolBEKpb7medUkc3CgS73Sxv6Agxawn61e4s1spXseeOjXZeRxkNBE0SnwI90-_g8Mo%3D&attredirects=1&d=1
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« Reply #9 on: June 10, 2014, 10:40:58 PM »
K K Iyer
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No takers for this article?

'From Release to Stick - One Frame at a Time Using high speed video to better understand catapult glider launch dynamics
by Paul Love, San Diego, CA, USA'

It's worth looking at. (Link in last post)
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« Reply #10 on: June 11, 2014, 01:31:08 AM »
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Im closely following this thread though this is a bit confusing,
Agree that the art of aeromodelling is lost and now its become just RC flying. Bang Head Bang Head
Its obvious from this threat itself. Shocked Shocked

Ashok.P
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« Reply #11 on: July 20, 2014, 10:35:56 PM »
K K Iyer
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Bump.
No one?
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« Reply #12 on: July 20, 2014, 11:15:11 PM »
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The PDF you mentioned is also referenced here - http://www.hippocketaeronautics.com/hpa_forum/index.php?topic=12247.0
Launch speeds seem to be in the range of 100mph+ for CLGs (suggesting even past 130mph), and one of the posters does refer to an 80mph+ launch for TLG, so 100mph expectation is not a surprise based on the compute.

1 minute of glide or more will, of course, also be determined by glide speed, etc., but you would have already thought of that.
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