PPRuNe Forums - View Single Post - Cirrus down Gundaroo, 06/10/23
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Old 7th Oct 2023, 21:11
  #85 (permalink)  
43Inches
 
Join Date: Oct 2007
Location: Aus
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Originally Posted by Squawk7700
The stec autopilot in the early Cirrus doesn’t have a IAS hold as it uses vertical speed. Speed could decay away as the altitude increases, which it doesn’t really, so it’s performing well with 315 hp.

So with the ADSB feed being ground speed, I’m assuming the speed “blip” early on of close to 20 knots is a 20 know westerly as he turns briefly onto “crosswind” on the departure track.

The profile appears to be a consistent climb to max altitude at what is probably the best rate you could get out it is, on the way to the pilots alleged preferred 10,000ft. The airspeed is low though… it’s a lowish speed with a high climbing angle into thinning air. If there was in fact ice building up, it’s building up on the underside of the wing, MU2 style. Add this to the laminar flow Cirrus wing at high angle of attack and when the wing drops, it will drop hard, potentially inverted.

We all know that a Cirrus isn’t getting out of a spin with no chute and I wouldn’t be at all surprised if nobody was able to pull it.

Of course this would all be pending icing levels and cloud at the time….
It would be very unlikely that a scenario like that would have the aircraft continue relatively straight ahead. Wing drop to inverted, I'd expect expect much larger heading variations.
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