Arcus full ballast with 2 pilots - Wrong stall speed

[zadmalck]

Hi all.

A full ballast Arcus with 2 pilots on board in a spiral with a speed of 80 to 90 km/h and a bank of 45 degrees should collapse. The Flap indicator in LXNAV indicated to put in L. The flap position being at 2.

Same for a full ballast duodiscus with 2 pilots on board.

For 2 pilots of 90 kg, the stall speed with the load factor for a 45 degree bank is 113 km/h for an Arcus. For a Duodiscus the stall at 45 degrees should be 107 km/h

The safety speed is (10 to 20%) should therefore be approximately between 130 km/h and 140 km/h for an Arcus. Between 125 and 135 km/h for a Duodiscus

Conclusion: With the other pilot in Arcus we should have stalled at 45 degrees of inclination and at 90 km/h

[Uros]

Arcus has max wing loading of 48 kg/m2 and a stall speed of 79 km/h at that wing loading with flap L in straight flight.

At 45 degrees bank, the stall speed increases for 19%, from 79 km/h to 98 km/h.

I just tested both stall speeds in Condor and they match perfectly.

[dgtfer]

Hi all.

A full ballast Arcus with 2 pilots on board in a spiral with a speed of 80 to 90 km/h and a bank of 45 degrees should collapse. The Flap indicator in LXNAV indicated to put in L. The flap position being at 2.

Same for a full ballast duodiscus with 2 pilots on board.

For 2 pilots of 90 kg, the stall speed with the load factor for a 45 degree bank is 113 km/h for an Arcus. For a Duodiscus the stall at 45 degrees should be 107 km/h

The safety speed is (10 to 20%) should therefore be approximately between 130 km/h and 140 km/h for an Arcus. Between 125 and 135 km/h for a Duodiscus

Conclusion: With the other pilot in Arcus we should have stalled at 45 degrees of inclination and at 90 km/h

I don't agree Thierry, in the real world you turn in a full duo between 90 and 100 km/h (80 without ballast), and in Arcus, with L flaps you can descend even further.
And in narrow thermals, the most effective climb is done with the straw slightly outside the turn.
But above all, if you want to climb fast, you have to be where it's climbing, no matter if you have to slide the glider from time to time to do it.