I've been upset on wave days in my Stemme.Â* Diving towards the leeward
slope of the mountains east of Albuquerque and pulling up when I felt a
bit of lift, the Stemme rolled uncontrollably to the right and the nose
started down.Â* I responded with forward stick and left aileron and
rudder.Â* The aircraft responded appropriately. This has happened more
than once but is not unexpected - just keep sufficient altitude for the
recovery.
On 7/25/2020 1:17 PM, John Carlyle wrote:
Regarding un-commanded upsets, I’m surprised only two people have so far written to say they have experienced them. Flying out of Mifflin, I’ve had about ten 80+ degree rolls over the last 10 years. They were all on strong (30 kt) ridge days with a bit of wave about, mainly in mid-May, but also in mid-October. Most occurred on Bald Eagle, but some were also on Tussey and Jacks. They mainly happened several thousand feet above ridge top, when I was either climbing to get back to Mifflin, or just loitering until the crosswind subsided a bit.
This is how I described one such experience, which happened at the end of my Diamond Distance flight in October 2010: “As I flew into the FAI finish sector Doris Grove radioed me her congratulations, then told me that I needed to stay airborne for another hour or so, as it was too turbulent and windy to land. Thus began the worst hour of flight I’ve ever experienced. The thermals were vigorous and plentiful this late in the day, and they were combining with the wind to roil the air in a way I’d never seen before. Suddenly the left wing went down, rolling me towards the ridge, fortunately some 2,000 feet below. Full right aileron and full right rudder did nothing to stop the roll, and the bank kept getting steeper. After what seemed like an hour but was probably about 10 seconds, my LS-8 responded and rolled level. But twenty seconds later the process repeated, this time to the right. Rapid jolts shook us violently in between and during the un-commanded rolls. I was more passenger than pilot, in the uncaring grip of an extremely powerful Nature.â€
I can categorically state that violent upsets can happen. On strong ridge days, especially when wave is around, I’ve found it prudent to stay well above the ridge top.
-John
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On Thursday, July 23, 2020 at 9:06:49 PM UTC-4, Eric Greenwell wrote:
Nick Kennedy wrote on 7/23/2020 1:27 PM:
Just last Saturday flying out of Nephi Ut in the flats of the valley over Yuba Res I had a thermal kick me into a 80 degree bank.
Full roll control wasn't enough so I pushed to about .1 G and full ruddered it back level. I've done this about 100 times in my soaring career.
Wow! That's never happened to me! In 6000+ hours of flying all over North America
- never have I been pushed more than 20 degrees or so. Just luck can't explain
that difference, so I wonder what we are doing differently that I've never been in
danger, and you've been there 100 times.
--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorg...ad-the-guide-1
--
Dan, 5J