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Title: TLG launch speed estimate Post by: K K Iyer on April 22, 2014, 09:45:14 PM 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/ (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. Title: Re: TLG launch speed estimate Post by: VC on April 22, 2014, 10:00:26 PM Maybe there is something to be learnt from this:
https://www.youtube.com/watch?v=DWpwLfVqBso&hd=1 (https://www.youtube.com/watch?v=DWpwLfVqBso&hd=1) 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 ;) Title: Re: TLG launch speed estimate Post by: K K Iyer on April 22, 2014, 10:33:08 PM 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 ;D Title: Re: TLG launch speed estimate Post by: VC on April 22, 2014, 10:55:16 PM Errrrrrrrrrrrrrrrrrr- corrected Sir.
:D :giggle: Title: Re: TLG launch speed estimate Post by: K K Iyer on April 22, 2014, 11:10:49 PM 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..." Title: Re: TLG launch speed estimate Post by: VC on April 22, 2014, 11:33:42 PM 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: Title: Re: TLG launch speed estimate Post by: K K Iyer on April 22, 2014, 11:50:02 PM 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... Title: Re: TLG launch speed estimate Post by: VC on April 22, 2014, 11:55:09 PM 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.
Title: Re: TLG launch speed estimate Post by: K K Iyer on May 14, 2014, 02:17:08 AM 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 Title: Re: TLG launch speed estimate Post by: K K Iyer on June 10, 2014, 10:40:58 PM 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) Title: Re: TLG launch speed estimate Post by: v2 eagle on June 11, 2014, 01:31:08 AM 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. :banghead: :banghead: Its obvious from this threat itself. :o :o Ashok.P Title: Re: TLG launch speed estimate Post by: K K Iyer on July 20, 2014, 10:35:56 PM Bump.
No one? Title: Re: TLG launch speed estimate Post by: crazycalvin on July 20, 2014, 11:15:11 PM The PDF you mentioned is also referenced here - http://www.hippocketaeronautics.com/hpa_forum/index.php?topic=12247.0 (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. |