On Friday, February 19, 2021 at 11:38:02 AM UTC-5, bgrly wrote:
On Thursday, February 18, 2021 at 7:12:31 PM UTC-6, wrote:
On Thursday, February 18, 2021 at 6:32:19 PM UTC-5, wrote:
This is the problem I'm referring too:

https://www.youtube.com/watch?v=use6PnxjO7s

Nick
T
That sort of accident has nothing to do with speed on final approach.

T8
Discussions at my club and at a FIRC prompted my research and writing a piece on my personal website. The link is below. I suspect or expect a few comments, as undoubtedly somebody will think I"m all wet. Mention of the huey is because that's what I know.

http://www.unofficialuseonly.us/gelbe.html

Brent, 7A ,

I have understood (though I can't give you a reference) the YT as marking the minimum recommended approach speed needed to complete the landing flare at max mass without water ballast in calm air. Modern gliders have a high rate of descent with airbrakes fully extended and gear down. The D2b flight manual status that the L/D in this configuration is approximately 5.8:1, which translates to a sink rate of roughly -10kts. In this condition you need enough airspeed to arrest the descent and flare. If the approach is too slow, the glider will mush and land heavily. The YT doesn't say anything per se about airspeed margin for wind gradient and gusts.

A variety of approaches can be found in the literature on the subject of approach airspeed in windy conditions, e.g.:

1.3 Vso plus the full wind speed (Soaring Association of Canada Student handbook p61) http://www.sac.ca/index.php/en/docum...011-optim/file
1.5 Vso plus half the gust speed if not otherwise specified in the POH (FAA glider manual pp 7-23 and 7-25) https://www.faa.gov/regulations_poli...h-8083-13a.pdf
1.5 Vso plus half the wind plus all the gust (Soaring Safety Foundation). https://www.soaringsafety.org/public...6-airspeed.pdf

They all give the same general advice, that is fly higher airspeed in windy and gusty conditions. I don't claim to know which exact formula which is best.

Ian IN