On Thursday, 18 February 2021 at 14:48:55 UTC, wrote:
On Thursday, 18 February 2021 at 13:11:35 UTC, Eric Greenwell wrote:
Nicholas Kennedy wrote on 2/16/2021 4:56 PM:
On many German gliders on the ASI is a yellow triangle.
This Yelloe Triangle on my ASw 20 and my LS3a is the factory recommended approach airspeed. This speed is 49 knots.
This has bothered me for a long time now, I think the factory did alot of pilots a disservice by putting this, to me anyway, very low number on there.
On both the above gliders, the max speed, normal landing flap flaps down, is 86 knots.
About 15 years ago my Gold Seal flight instructor Bob Faris, CX,indicated to me in his LS3 he planned on a much higher speed in the pattern, like 70-75 knots depending on conditions. I followed suit ever since.
Since so many gliders have 49 knots for the Yellow Triangle, I think this might be a regulatory
requirement, not a choice by the glider manufacturer. Perhaps gliders are required to have an
approach speed no higher than 49 knots at a certain weight with the regulation required control
authority.
--
Eric Greenwell - Washington State, USA
https://sites.google.com/site/motorg...ad-the-guide-1
In the EASA CS22 specification for ASI markings it includes "a yellow marking (triangle) for the lowest approach speed (at maximum weight without water ballast) *recommended by the manufacturer*". (My stars). As far as I can see there is neither a set value nor a formula for deriving it from e.g. stall speeds

There's probably some approximation or rounding

49 and 54 knots might sound like precision to us, but these are 90 and 100 km/h. 86 kts is 160 km/h