JS-1 Handling Bad?

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Lenticular
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JS-1 Handling Bad?

Post by Lenticular » Sat Jun 19, 2021 5:20 am

Hi,

Is there an issue with the JS-1 flight model?

I find it quite unstable, prone to stalling, and generally rather awkward at low speed.

I keep flying it back-to-back with the Antares, Diana2, and Cirrus, and all the others, while obviously different, are much better behaved than either of the JS-1.

As I write this, I did remember that I set slightly aft CoG (-1.2).

Is the JS-1 known to be unstable with ANY aft CoG?

Despite this, it still doesn't like low speed generally, and is quite difficult to maintain a constant low speed (e.g. when thermalling).

The 21m seems worse than the 18m, and both seem worse than the Antares.
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wickid
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Re: JS-1 Handling Bad?

Post by wickid » Sat Jun 19, 2021 8:26 am

What speed are you trying to fly? With some bank and full water 110 kph is really about the minimum speed it still flies.
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Lenticular
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Re: JS-1 Handling Bad?

Post by Lenticular » Sat Jun 19, 2021 11:37 am

No ballast. I was attempting to maintain 45 kts (min sink speed) in stable ridge lift.

There was "light turbulence" but otherwise nothing too extreme (wind speed/direction was constant and the ridge line fairly straight in the area it was having problems).

I think I may be under-estimating the (dynamic) stability of the flight model. Reading some information earlier on the use of flaps, it apparently makes some gliders very prone to low speed (not stall) wing drop.

Some more experimentation is required.

I had flap 5 set...
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Bre901
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Re: JS-1 Handling Bad?

Post by Bre901 » Sat Jun 19, 2021 1:40 pm

Do you have a force-feedback joystick ?
The last (and only) person I heard having low-speed handling issues with the JS1 had not.
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johngalloway
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Re: JS-1 Handling Bad?

Post by johngalloway » Sun Jan 30, 2022 5:22 pm

I used to own a JS1 and it is extremely stable and benign in its handling . 45 knots is unrealistically slow.

Kestrel_BY
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Re: JS-1 Handling Bad?

Post by Kestrel_BY » Mon Jan 31, 2022 6:28 pm

Hi there, I've been flying the JS1-18 quite often these days as it is one of my favorite 18m (I do prefer the ASG29's handling but the JS1 seems a little more versatile plus it does really well in SGP rules, with the 48 kg/m² limitation), so I might be able to give you a few tips on the glider.

I fly it using mainly two settings, one for slower and harder weathers, and one for good meteos (when the thermals are above 1.5 to 2 m/s average).


Slow weather : 50kg/m² - CG -2cm
The glider flies really well with these settings, it is very reactive with still a good feeling of inertia (which I like). I thermal it at around 105/110 km/h (56 to 59 knots) with flap settings 5, where I generally outclimb the ventus at the same wingloading. One might recommend "sending the nose" with the rudders like you'd do on a Duo Discus for example, but I feel like it's not necessary considering how agile the glider is.

Normal and fast weathers : 53.5kg/m² (MTOW) - CG -3cm
Set like this, the glider requires a little more attention in thermals, but it's a small price you have to pay to keep up with the others who will indeed fill their JS3's and Ventus' to the MTOW. I tend to climb at around 110/115 km/h (59 to 62 knots) with flap settings 5. In larger thermals one may even circle it a little faster with flap setting 4 (as the flight manual recommands) but that's rare.

Without ballasts I would thermal it at around 95 km/h (~50/52 knots).

I do have to recognise that JS' and Schempp-Hirth's gliders slow speed behaviors are generally a little "harsh", while a Schleicher/DG/LS/Glassflügel will tend to experience a loss in control authority and an increased sink when slowing down too much, these (JS and Schempp-Hirth) tend to shake and quickly enter into a spin if you don't react (the harsher, in my opinion, is the JS3), so these might not be the easiest gliders to master. The JS1 is a modern glider which, as its counterparts, requires a little time to adapt. If you don't manage to fly it smoothly, I would recommend training with the Antares, and gradually increasing the Antares' wing loading to train, as it is a very easy and gentle 18m which you can thermal relatively slow (~105 km/h) at its MTOW.

With the 21m wingspans you need to fly the glider a little faster in thermals, and anticipate much more any inputs on the controls. Do note that the glider controls are much less homogeneous in 21m than they are in 18m. Else it's a pretty decent open class glider with a fairly good "handling-to-performance" ballance (compared to a nimbus for example, which is terrible).

Oh yeah, one last thing, I tend to fly my gliders with the CG much more aftward than the average pilot (generally 3/4th aft) so you might want to set it 1 or 2 cm forward compared to what I do.
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eRock
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Re: JS-1 Handling Bad?

Post by eRock » Tue Feb 01, 2022 1:03 am

I had similar problem with JS1 till I plug power adapter in, for the force feedback, to find joystick trim was out too much. I hence always have FF on now these days.
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