Service Ceiling L23 - Litigation

On Sunday, December 20, 2020 at 1:43:57 AM UTC-5, wrote:
Grand Teton is 13,776 ft. Icefloe Lake is 10,652 ft. If the first frame began at release altitude then they were slightly below and to the south of the summit of Grand Teton. In 3:09 they lost 3100 feet give or take.


https://www.youtube.com/watch?v=lvWNkP-NzAQ

The saddle of the ridgeline level with the glider Figure 7, time stamp 3:06, is 11,500. It doesn't look like there was any altitude loss to speak of, and perhaps a small gain between 2:57 and 3:06.

If a spin event happened shortly after 3:06, it may not have happened like in the linked video. When stalled in a full rudder over slipping turn of 30 degrees bank, the L-23 spins into the low wing, -against- the rudder. The entry looks similar to Figure 7 (but desirably without rocks). In that case, expect an excursion to 60 degrees nose low pitch, about 180 degrees of (slow) auto rotation before recovery and a few hundred feet of altitude lost. I have done many times with students as a part of a lesson on slips and slipping turns.

T8

On Sunday, December 20, 2020 at 5:56:29 AM UTC-8, wrote:
On Sunday, December 20, 2020 at 1:43:57 AM UTC-5, wrote:
Grand Teton is 13,776 ft. Icefloe Lake is 10,652 ft. If the first frame began at release altitude then they were slightly below and to the south of the summit of Grand Teton. In 3:09 they lost 3100 feet give or take.


https://www.youtube.com/watch?v=lvWNkP-NzAQ
The saddle of the ridgeline level with the glider Figure 7, time stamp 3:06, is 11,500. It doesn't look like there was any altitude loss to speak of, and perhaps a small gain between 2:57 and 3:06.

If a spin event happened shortly after 3:06, it may not have happened like in the linked video. When stalled in a full rudder over slipping turn of 30 degrees bank, the L-23 spins into the low wing, -against- the rudder. The entry looks similar to Figure 7 (but desirably without rocks). In that case, expect an excursion to 60 degrees nose low pitch, about 180 degrees of (slow) auto rotation before recovery and a few hundred feet of altitude lost. I have done many times with students as a part of a lesson on slips and slipping turns.

T8

That is very helpful information Tango. I'll have to try that. I've thought that in an uncoordinated stall the aircraft will roll "to the rudder", not against the rudder. So, in the example you describe I would have thought that the "outside" wing, in this case the high wing, would be in the wind shadow of the fuselage and so would stall first thereby having the aircraft roll to that wing - sometimes called "over the top". On the other hand I have not flown an L-23. Also, maybe the 30 degree bank makes a difference.. I have been wrong in a very important circumstance.

On Sunday, December 20, 2020 at 5:56:29 AM UTC-8, wrote:
On Sunday, December 20, 2020 at 1:43:57 AM UTC-5, wrote:
Grand Teton is 13,776 ft. Icefloe Lake is 10,652 ft. If the first frame began at release altitude then they were slightly below and to the south of the summit of Grand Teton. In 3:09 they lost 3100 feet give or take.


https://www.youtube.com/watch?v=lvWNkP-NzAQ
The saddle of the ridgeline level with the glider Figure 7, time stamp 3:06, is 11,500. It doesn't look like there was any altitude loss to speak of, and perhaps a small gain between 2:57 and 3:06.

If a spin event happened shortly after 3:06, it may not have happened like in the linked video. When stalled in a full rudder over slipping turn of 30 degrees bank, the L-23 spins into the low wing, -against- the rudder. The entry looks similar to Figure 7 (but desirably without rocks). In that case, expect an excursion to 60 degrees nose low pitch, about 180 degrees of (slow) auto rotation before recovery and a few hundred feet of altitude lost. I have done many times with students as a part of a lesson on slips and slipping turns.

T8

If you look at the photos of the accident site it is apparent that there was not that much altitude loss between spin entry and impact, perhaps 500 - 1000 feet. Yes, the full video would be very helpful in analyzing the sequence of events. Certainly, the lawyers have access to it, which no doubt will be presented at trial (assuming it goes to trial).

Tom