JS3 chatter

On Sunday, December 18, 2016 at 3:28:59 PM UTC-5, TS wrote:
On Sunday, 18 December 2016 17:46:45 UTC+1, jfitch wrote:
On Sunday, December 11, 2016 at 4:11:36 PM UTC-8, wrote:
Thanks to J.Nieuwenhuize for posting this link Jonker's aerodynamicist Johan Bosman pictures of the JS3. http://www.imgrum.net/user/johanjbosman/697025039

As suggested, the Akaflieg München Mü31 article is also a good read. http://www.akaflieg.vo.tum.de/index.php/en/mue-31-en

Go around-come around...interesting how we're back to the AS Ka-6E shoulder wing. Can't wait to inspect how they did the automatic hook-ups. Really like the retractable tail wheel too. Congratulations Johan Bosman.

We'll see...pretty is as pretty does.

The 26 fueselage is considerably different than a Ventus. Place the two side by side and there is no doubt. Different shape, different cockpit, different canopy. Everything different. Place a 26 fuselage next to a JS1 and you cannot tell them apart. Even many of the details inside are the same. I'm not complaining about it, I doubt the 26 fuselage is legally protectable intellectual property. But the question was posed above.




The aerodynamic shape of the JS1b/c is a 100% direct copy of the ASH26. They took an existing ASH26 fuselage, and made a negative mould of it.

The internals are different.

also, all this business about canopy shape is irrelevant. once you have a negative mold for the 26, you can define the canopy shape however you want.

At 02:41 17 December 2016, wrote:
On Friday, December 16, 2016 at 6:02:19 PM UTC-5, Jonathan St.
Cloud wrote:
The product placement is a bit perplexing to me. The thought the
JS-1B
was a 15/18 glider.

Nope. Production JS1 was 18M from the beginning.


Actually the option of 15m tips was a consideration for Jonkers in the
initial stages of JS1 production but most customers did not want it!

On Monday, December 19, 2016 at 9:09:21 AM UTC-5, ND wrote:
On Sunday, December 18, 2016 at 3:28:59 PM UTC-5, TS wrote:
On Sunday, 18 December 2016 17:46:45 UTC+1, jfitch wrote:
On Sunday, December 11, 2016 at 4:11:36 PM UTC-8, wrote:
Thanks to J.Nieuwenhuize for posting this link Jonker's aerodynamicist Johan Bosman pictures of the JS3. http://www.imgrum.net/user/johanjbosman/697025039

As suggested, the Akaflieg München Mü31 article is also a good read. http://www.akaflieg.vo.tum.de/index.php/en/mue-31-en

Go around-come around...interesting how we're back to the AS Ka-6E shoulder wing. Can't wait to inspect how they did the automatic hook-ups. Really like the retractable tail wheel too. Congratulations Johan Bosman.

We'll see...pretty is as pretty does.

The 26 fueselage is considerably different than a Ventus. Place the two side by side and there is no doubt. Different shape, different cockpit, different canopy. Everything different. Place a 26 fuselage next to a JS1 and you cannot tell them apart. Even many of the details inside are the same. I'm not complaining about it, I doubt the 26 fuselage is legally protectable intellectual property. But the question was posed above.




The aerodynamic shape of the JS1b/c is a 100% direct copy of the ASH26. They took an existing ASH26 fuselage, and made a negative mould of it.

The internals are different.

also, all this business about canopy shape is irrelevant. once you have a negative mold for the 26, you can define the canopy shape however you want..

The canopy shape is defined by the aerodynamic profile. The trimmed configuration and contour of the canopy frame cut out may change, as it did in the evolution of the Schleicher fuselages.
I suspect that Bosman is really chasing details and reduced the canopy to change how it affects laminar flow on the forward fuselage.
FWIW
UH

At 20:20 19 December 2016, wrote:
On Monday, December 19, 2016 at 9:09:21 AM UTC-5, ND wrote:
On Sunday, December 18, 2016 at 3:28:59 PM UTC-5, TS wrote:
On Sunday, 18 December 2016 17:46:45 UTC+1, jfitch wrote:
On Sunday, December 11, 2016 at 4:11:36 PM UTC-8,

=
wrote:
Thanks to J.Nieuwenhuize for posting this link Jonker's
aerodynamic=
ist Johan Bosman pictures of the JS3.
http://www.imgrum.net/user/johanjbosm=
an/697025039
=20
As suggested, the Akaflieg M=C3=BCnchen M=C3=BC31 article is
also
a=
good read. http://www.akaflieg.vo.tum.de/index.php/en/mue-31-en=20
=20
Go around-come around...interesting how we're back to the AS
Ka-6E
=
shoulder wing. Can't wait to inspect how they did the automatic hook-ups.
R=
eally like the retractable tail wheel too. Congratulations Johan
Bosman.=20
=20
We'll see...pretty is as pretty does.
=20
The 26 fueselage is considerably different than a Ventus. Place the
t=
wo side by side and there is no doubt. Different shape, different
cockpit,
=
different canopy. Everything different. Place a 26 fuselage next to a
JS1
=
and you cannot tell them apart. Even many of the details inside are the
sam=
e. I'm not complaining about it, I doubt the 26 fuselage is legally
protect=
able intellectual property. But the question was posed above.
=20
=20
=20
=20
The aerodynamic shape of the JS1b/c is a 100% direct copy of the
ASH26.=
They took an existing ASH26 fuselage, and made a negative mould of
it.=20
=20
The internals are different.
=20
also, all this business about canopy shape is irrelevant. once you have
a=
negative mold for the 26, you can define the canopy shape however you
want=
..

The canopy shape is defined by the aerodynamic profile. The trimmed
configu=
ration and contour of the canopy frame cut out may change, as it did in
the=
evolution of the Schleicher fuselages.
I suspect that Bosman is really chasing details and reduced the canopy to
c=
hange how it affects laminar flow on the forward fuselage.
FWIW
UH


With absolutely no knowlage at all I offer these speculations .
The JS1 polar as on their web site shows little difference between the 18
m
and the 21m at the same wing loading ,In other words the span makes less
difference than the wing loading.
There have been tales of JSI spinning off tow,I assume that is because
pilots
are loading to max water to get the performance .
When I look at the JS3 it looks as if they have added di hedral and washout

to increase the stability and shortened the wing span to get the wing
loading.
As high as possible .
It should be a rocket if the conditions are strong enough.

Hi
Some interesting speculations. Here are a few facts:

The JS3 wing is in essence the same as that of the JS1 Evo except for the inner 1m were the transition to fuselage starts. The evo wingtip was designed for the JS3 but was used on the JS1 as the JS3 fuse was not yet ready 3 years ago. The evo wingtip proved to be very good in terms of performance and handling improvement. That served to confirm the new wingtip airfoil and 3rd generation winglet design methodology.

The fuselage is the result of a huge basic research effort. We took 2 year to learn how to design a modern glider fuselage. The fuselage was just about ready when we discovered a fundamental problem inherent to most high wing configurations that will offset any gains due to the high wing. We then had to redesign the fuse to remove that problem. That took about 2 years. We use CFD analysis exclusively for this development work. Bossie (Johan Bosman) spent 3 years (PhD) to properly calibrate the software for our flow regime. A lot of effort went into the wing fuse junction. This is still a very difficult area to design properly.

The moulds for the wings was started in Feb 2016 and completed in June 2016.. (we used the mould-plug-mould route to composite moulds). The detail design on the JS3 was started in March 2016 and was basically completed in beginning of NOv 2016. The total design effort(not building of anything, just design) took approx 25000 man hours( 16 engineers)

The fuselage mould was started on 4 Aug 2016. We stated building the fuse in Oct 2016 and the wings in Nov 2016. An integrated design approach was used where everything was designed simultaneously, ie airframe, moulds, tooling and manufacturing method. So when the design was completed, so was most of moulds, tooling and jigging. The prototype were therefore really built as close to as is possible to a production aircraft. We tried to use as many JS1 parts as possible but most systems and parts are completely new.

The first prototype as accumulated 20 h over the week since the test flight and the envelope is opened to full wing loading (60 kg/sqm) and 270 kph. The stall speed matches the calculated value perfectly. The handling is really good, JS1++. The performance.. well we are satisfied.

Regards
Attie Jonker

Thank you, Attie! You guys have made another beautiful sailplane!

Steve Leonard

Thanks for the update, Attie.
Jim

On Monday, December 19, 2016 at 9:41:33 PM UTC-7, wrote:
Hi
Some interesting speculations. Here are a few facts:

The JS3 wing is in essence the same as that of the JS1 Evo except for the inner 1m were the transition to fuselage starts. The evo wingtip was designed for the JS3 but was used on the JS1 as the JS3 fuse was not yet ready 3 years ago. The evo wingtip proved to be very good in terms of performance and handling improvement. That served to confirm the new wingtip airfoil and 3rd generation winglet design methodology.

The fuselage is the result of a huge basic research effort. We took 2 year to learn how to design a modern glider fuselage. The fuselage was just about ready when we discovered a fundamental problem inherent to most high wing configurations that will offset any gains due to the high wing. We then had to redesign the fuse to remove that problem. That took about 2 years. We use CFD analysis exclusively for this development work. Bossie (Johan Bosman) spent 3 years (PhD) to properly calibrate the software for our flow regime. A lot of effort went into the wing fuse junction. This is still a very difficult area to design properly.

The moulds for the wings was started in Feb 2016 and completed in June 2016. (we used the mould-plug-mould route to composite moulds). The detail design on the JS3 was started in March 2016 and was basically completed in beginning of NOv 2016. The total design effort(not building of anything, just design) took approx 25000 man hours( 16 engineers)

The fuselage mould was started on 4 Aug 2016. We stated building the fuse in Oct 2016 and the wings in Nov 2016. An integrated design approach was used where everything was designed simultaneously, ie airframe, moulds, tooling and manufacturing method. So when the design was completed, so was most of moulds, tooling and jigging. The prototype were therefore really built as close to as is possible to a production aircraft. We tried to use as many JS1 parts as possible but most systems and parts are completely new.

The first prototype as accumulated 20 h over the week since the test flight and the envelope is opened to full wing loading (60 kg/sqm) and 270 kph. The stall speed matches the calculated value perfectly. The handling is really good, JS1++. The performance.. well we are satisfied.

Regards
Attie Jonker

Thanks so much for taking the time to explain the process to us. I had to double check the number of man hours spent in the design effort. 25k hours?!?!? Wow! Congrats on another beautiful ship and I can't wait to fly one..

Bruno - B4

At 04:54 20 December 2016, JS wrote:
Thanks for the update, Attie.
Jim

Thank you Attie that is very illuminating
Jon

Mic drop.