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JS3 chatter



 
 
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  #21  
Old December 15th 16, 05:01 PM posted to rec.aviation.soaring
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Default JS3 chatter

The included 3-view only shows 15M. Is it not intended to be 15-18M?


  #22  
Old December 15th 16, 05:16 PM posted to rec.aviation.soaring
Steve Leonard[_2_]
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On Thursday, December 15, 2016 at 10:01:02 AM UTC-6, wrote:
The included 3-view only shows 15M. Is it not intended to be 15-18M?


Spec page says it has a 4 piece wing. Doesn't look like enough "crank" in the wing to be a real trailer issue. I would guess there may be another span option to follow soon.

Steve Leonard
  #23  
Old December 15th 16, 05:32 PM posted to rec.aviation.soaring
Tony[_5_]
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It was noted on Facebook that the Vne chart on the panel lists 15m and 18m spans. Jump to your own conclusions...
  #24  
Old December 15th 16, 06:15 PM posted to rec.aviation.soaring
krasw
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My calculator says 267 kg empty with 8,7m2 wing.
  #25  
Old December 16th 16, 02:43 PM posted to rec.aviation.soaring
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Polydihedral wing already has an increased roll stability, moving the wing upward increase further roll stability.

I don't know if this is an advantage.

  #26  
Old December 16th 16, 05:39 PM posted to rec.aviation.soaring
Martin Gregorie[_5_]
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On Fri, 16 Dec 2016 05:43:36 -0800, orsica wrote:

Polydihedral wing already has an increased roll stability, moving the
wing upward increase further roll stability.

More to the point, tip dihedral and polyhedral both give more stability
that a single panel dihedralled wing for a given tip rise jjust as a gull
wing gives less stability.

Whether you get more or less stability from a given dihedral schema
depends on both the amount of wing sweepback and the hight of the tip
above the root.

The JS3 and Arcus both use sweepback as well as polyhedral, so can use
less dihedral to achieve the required lateral stability.


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |
  #27  
Old December 16th 16, 06:30 PM posted to rec.aviation.soaring
Jonathan St. Cloud
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Beautiful sailplane. Does anyone else think the forward fuselage, looks like it barrowed lines from the Schleicher series, ASW-24,27,28, ASG-29? The tapper looks different.
  #28  
Old December 16th 16, 10:40 PM posted to rec.aviation.soaring
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On Friday, December 16, 2016 at 9:31:01 AM UTC-8, Jonathan St. Cloud wrote:
Beautiful sailplane. Does anyone else think the forward fuselage, looks like it barrowed lines from the Schleicher series, ASW-24,27,28, ASG-29? The tapper looks different.



A South African newsgroup has some more info about the glider:

http://www.avcom.co.za/phpBB3/viewtopic.php?t=183997

Looking at the 3-view drawing on the Jonker website, and based on the above website, I think that the JS3 wing is the JS1C wing with the inner 1.5 meters removed, and with appropriate changes such as relocated spoilers. The 18m version will use the outer panels from the 21m version of the JS1C. That will give it a wing area of only 106 sq ft in the 18 meter mode (for comparison, the ASG29 is 113).

Interesting that FES will be an option. At the Reno Convention, Luka told me that the Jonkers didn't like FES because they thought the disturbed airflow from the folded props would reduce performance. They wanted a prop design like the one that has recently appeared on the GP14. Perhaps with the JS3's low nose and high mounted wing the Jonkers now feel that the disturbed airflow will not reach high enough to affect the wing.

Video here of the takeoff roll on the first flight. No use of spoilers, and the glider had no tendency to drop a wing:

http://tinyurl.com/z57pvhx

The only problem I see with the JS3 is that the side mounted swiveling vent is gone. I wonder why they got rid of it. Will there be an option to mount a vent in the panel?
  #29  
Old December 16th 16, 11:32 PM posted to rec.aviation.soaring
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More interesting tidbits he http://www.avcom.co.za/phpBB3/viewto...p?f=1&t=183997

Such as:

" Here is a little info released about the prototype machine .
It was flown in the 15 meter configuration .It has 18 meter tip option .really clean at the end of the tailfeathers - retractable tailwheel / no horn on the rudder / all ASI and pressure sensing probes on the tailplane extremities instead of the fin post to reduce interference drag .
Higher aspect ratio than current 15 meter crop with a 8.7 squ. meter wing .
Projected higher max wing loading at perhaps 61 kg. / squ. meter still to be ratified ?"

"The canopy now seals with car type door seals, ensuring no airflow/pressure gets lost at the joints. It also has an electrically operated air vent in front of the instrument panel, which works opposite to the conventional air vent. This is to ensure a better closing seal and prevent air flow coming in when you dont want it. The tanks are forward and aft of the main spar, to allow it to get to the 525kg mark on the small wing (I heard a figure of up to 68kg/m2, but I'm sure I heard wrong) The tips are interchangable direct from the Js1 Evo to the Js3 to make it the 18m version It also has an electric operated back rest

The 2 Js3's are going to be shipped via airfrieght to Aus for the word champs "
  #30  
Old December 17th 16, 12:02 AM posted to rec.aviation.soaring
Jonathan St. Cloud
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The product placement is a bit perplexing to me. The thought the JS-1B was a 15/18 glider. They stopped production of the B in favor of the JS1c. Now the Js1c and the Js3 will be competing for many of the same customers who want an 18 meter bird. If the reports are to be believed a wing area of 106 sq. ft. does not leave much area to support the weight of a sustainer system. 2/3 of the ASG-29's built have been sustainers and are flying with a min wing loading of 8.6-8.8 pounds.

The self launch Js1c is a great idea and will likely take away much demand from the ASH-31. Just wondering why make a 15/18 to compete with your already successful 18 meter bird. Why not build a 2 seat 20 meter glider, with an option for clubs to buy it at 18 meters with fixed gear. Just musings from a rainy Southern California.

On Friday, December 16, 2016 at 2:32:44 PM UTC-8, wrote:
More interesting tidbits he http://www.avcom.co.za/phpBB3/viewto...p?f=1&t=183997

Such as:

" Here is a little info released about the prototype machine .
It was flown in the 15 meter configuration .It has 18 meter tip option .really clean at the end of the tailfeathers - retractable tailwheel / no horn on the rudder / all ASI and pressure sensing probes on the tailplane extremities instead of the fin post to reduce interference drag .
Higher aspect ratio than current 15 meter crop with a 8.7 squ. meter wing
 




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