JS3 is released

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OXO
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JS3 is released

Post by OXO » Sat Jan 23, 2021 3:17 pm

:)
Chris Wedgwood,
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timbaeyens
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Re: JS3 is released

Post by timbaeyens » Sat Jan 23, 2021 3:19 pm

Flown for 5 minutes already. Had to try 8)
TT

arneh
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Re: JS3 is released

Post by arneh » Sat Jan 23, 2021 5:26 pm

Wohoo! Finally I practice in it until I get my real one :D

Though I notice that the 18m JS3 has significanly worse polar in Condor than the polar JS has published for it, and which Idaflieg seems to confirm. Though maybe you have better data than JS's published data...

With the increased performance of the Ventus 3 in 2.1.6 it has basically the same high speed performance as the JS3, despite having a max wing loading of 55 vs 60 for the JS3. That doesn't seem right, wing loading is king for high speed performance. Is there some sort of equalization going on between the gliders in Condor to not make one glider too dominant?

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Re: JS3 is released

Post by OXO » Sat Jan 23, 2021 5:39 pm

arneh wrote:
Sat Jan 23, 2021 5:26 pm
Wohoo! Finally I practice in it until I get my real one :D

Though I notice that the 18m JS3 has significanly worse polar in Condor than the polar JS has published for it, and which Idaflieg seems to confirm. Though maybe you have better data than JS's published data...

With the increased performance of the Ventus 3 in 2.1.6 it has basically the same high speed performance as the JS3, despite having a max wing loading of 55 vs 60 for the JS3. That doesn't seem right, wing loading is king for high speed performance. Is there some sort of equalization going on between the gliders in Condor to not make one glider too dominant?
Thats not correct. look again. Ventus 3 is worse than JS3 at high speed. ( don't forget to enable "fixed ballast")

As there is no available polar for Ventus 3, we have to invent it from similar gliders and previous generation (Ventus 2). Its not exact, and we would dearly love to see official Schempp Hirth or Idaflieg data for the Ventus 3.
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arneh
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Re: JS3 is released

Post by arneh » Sat Jan 23, 2021 6:00 pm

OXO wrote:
Sat Jan 23, 2021 5:39 pm

Thats not correct. look again. Ventus 3 is worse than JS3 at high speed. ( don't forget to enable "fixed ballast")
At 201 km/h (a typical cruising speed with these gliders), V3 at 55.4 kg/m2, JS3 at 60.3 kg/m2, the V3 has a glide ratio of 36.0, the JS3 has a glide ratio of 36.1. That is pretty much the same, despite the 5kg/m2 difference in wing loading. Put the JS3 at 55.7 kg/m2 and its glide ratio drops to 34.2. So at the same wing loading the V3 is much better. Even the old ASG 29 has better performance at the same wing loading as a JS3 in Condor.

But my main point wasn't that the V3 (or ASG 29) was too good, it may well be accurate, and it's hard to know the real difference. But the main point was that the JS3 polar doesn't match the published one from JS (and confirmed by Idaflieg), which is significantly better. The JS polar has a glide ratio of about 39 at 200 km/h @ 60 kg/m2.

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Re: JS3 is released

Post by arneh » Sat Jan 23, 2021 6:22 pm

In Condor 2 even the JS1 18m has better performance than the JS3 at the same wing loading.

JS1 18m @53.6 kg/m2 @ 200 km/h, glide ratio 34.9
JS3 18m @53.7 kg/m2 @ 199 km/h, glide ratio 33.9

JS1 18m @53.6 kg/m2 @ 220 km/h, glide ratio 29.8
JS3 18m @53.7 kg/m2 @ 220 km/h, glide ratio 28.9

That doesn't make any sense! The JS3 has a lot of aerodynamic improvements from the JS1.

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Re: JS3 is released

Post by timbaeyens » Sat Jan 23, 2021 7:02 pm

TT

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Re: JS3 is released

Post by OXO » Sat Jan 23, 2021 7:12 pm

timbaeyens wrote:
Sat Jan 23, 2021 7:02 pm
v3 has been tested @ Idaflieg
https://www.youtube.com/watch?v=1q3g-7p ... otographie
We know, but the data is not available.
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Re: JS3 is released

Post by wickid » Sat Jan 23, 2021 7:15 pm

May I add to this discussion:

https://www.soaringspot.com/en_gb/35th- ... s/18-meter

JS3 and Ventus 3 seem to be on par when comparing the WGC results.
PH-1504, KOE

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Re: JS3 is released

Post by DarkSpeed » Sat Jan 23, 2021 7:23 pm

I can confirm Arnes numbers.
In Condor the polar is significant worse than the official polar from Jonkers, wich is at least confirmed for the best glide from Idaflieg.

Example:
Jonkers: -1,35 m/s @200 kmh
Condor: -1,5 m/s @ 200 kmh


With same wingloading JS3 should be equal or probably better than ASG29, JS1 and Ventus3. With the 60 kg/m² it should be significant better.

I am wondering, that the offical polar is not used in Condor, maybe you can explain why you used another one? I hope you can fix the polar in next update.

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Re: JS3 is released

Post by arneh » Sat Jan 23, 2021 7:32 pm

wickid wrote:
Sat Jan 23, 2021 7:15 pm
May I add to this discussion:

https://www.soaringspot.com/en_gb/35th- ... s/18-meter

JS3 and Ventus 3 seem to be on par when comparing the WGC results.
Right, but performance is more than just high speed glide ratio. From those who have compared them in real life the consensus seems to be that the JS3 glides better (when both at max ballast), the V3 advantage is in the climb, making them quite comparable in total results.

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Re: JS3 is released

Post by Uros » Sat Jan 23, 2021 8:05 pm

We've put a lot of effort into final polars for Ventus and JS3.

This is the information we considered:
- the JS3 official polar
- the JS3 Idaflieg polar
- the WGC and latest Grand prix final results
- the feedback from pilots (some world class)
- the physics considerations (like how MTOW and wingload affect performance)

It's well known that when you compare two equally optimized gliders at the same wingload at high speed, the plane with higher wing area (also higher mass) will glide better. This is simply because higher Reynolds numbers give less drag. That's why model planes will never glide as well as full scale gliders and it's also why Ventus is preferred at grand prix racing where there is a wingload limit. Also, please note JS3 uses the same airfoil as JS1 (which is not a bad thing, but it's also something to consider).

So why is JS3 polar in Condor different from their official one?
- the Idaflieg JS3 polar is different to official JS3 polar
- the Idaflieg JS3 polar was measured at wingload of 55 which results in much higher L/D (cca 2 points) than at low wing loading. We will simulate this effect in the next Condor patch/version.

The final result is that the Ventus in Condor will climb a bit better at its full load and glide a bit better with the same wingload as JS3. JS3 will glide a bit better at full load at all speeds. Attached are the current Condor polars at max wingload.

If we get more or better data we are will of course update the performance.
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arneh
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Re: JS3 is released

Post by arneh » Sat Jan 23, 2021 8:34 pm

Thank you or your reply!

If you actually have the Idaflieg results and based the Condor polar on that, then you may have more accurate data then I have access too, as I haven't seen the Idaflieg JS3 polar. I just saw that Jonker claimed it correlated very well with their own polar. That may seem a bit loose with the facts if the difference is actually about 10%, which is the difference at high speed between Condor polar and JS polar. That is a quite big difference in my eyes.

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Re: JS3 is released

Post by DarkSpeed » Sat Jan 23, 2021 10:00 pm

Thank you very much for the explanation and keep up your great work.

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Re: JS3 is released

Post by TimKuijpers » Sun Jan 24, 2021 2:41 pm

wickid wrote:
Sat Jan 23, 2021 7:15 pm
May I add to this discussion:

https://www.soaringspot.com/en_gb/35th- ... s/18-meter

JS3 and Ventus 3 seem to be on par when comparing the WGC results.

So please upgrade the ASG29 and JS1 then please :roll:

https://www.soaringspot.com/en_gb/34th- ... 1-21/total

Of course it would be silly to look at the results in order to define the performance of a glider..
Also what is overlooked here is that a polar is just a static performance: one speed, one sinkrate.
But what happens in the dynamic situation? Changing angle of attack, the infamous flat part in the CL/Alpha curve, can make much more difference than a slightly better polar. The Ls7 is a perfect example.

Translate this to the performance of the Ventus, which was designed from the philosophy to make the glider fit the habits of a pilot in order to extract maximum performance. Where as most other gliders were just designed to perform well on the drawing board and (if lucky) make the pilot adjust his/her behaviour to get the performance out of the glider. I truly believe that this is what makes the Ventus perform so well in competitions/crosscountry and the JS3 has not jet been able to make a big difference. If a glider performs very well at 240km/h, you still need a pilot that dares to fly 240km/h AND is able to hit the thermals, core them straight away. You need a very high cloudbases to actually fly those speeds for a while.. In the Netherlands it will be a challenge. But if this is what aerodynamics will allow, over time pilots will adjust (some sooner than others). I'm a big fan of clubclass gliding, (admitted, mainly money driven :wink: ) and it gives so much joy to keep up with the 10x more expensive gliders. The only way that that's possible is in an active sky where you can more easily make use of the energy. But as soon as there is even the smallest glide through dead air, you're gone. In condor you'll agree that there is not much of dynamic flying going on, and most of the time we fly a fixed speed between climbs for minutes. This of course favours the glider that performs best on paper, disregarding any handling advantages another glider might have.

I must say I'm biased to believe that the JS3 should indeed be significantly better at high speed. I'm however flying condor for the competition part and then it doesn't matter which polar a glider has, I'll chose the polar of my liking (so Uros' picture is very usefull indeed) and everybody else can do the same. In that light it's maybe better the JS3, Ventus and ASG29 are much alike so no matter which glider the best pilot wins. When it comes to polars though it is a bit sad that the best performing 15m glider of the last decade won't seem to be any good in condor anymore with the performance enhanced Ventus 3 and JS3. Condor is now so realistic you indeed need to bring money in order to win :lol:


Now, keep the discussion going please. I find it very interesting and lockdown is far from over here :lol:
Think positive, flaps negative.

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