On Wednesday, February 1, 2017 at 11:58:01 PM UTC-5, Sierra Whiskey wrote:
[...]
My Two Cents:
If the handicapping of gliders were quantifiable through the use of a formula that accounted for the performance of the glider in order to actually level the playing field of the aircraft and allow for a measure of the pilot then the introduction of modern gliders to the class would make more sense. Correct me if I am wrong, but for over a decade the US handicap system has been more of an arbitrary assignment than a calculation.

I look at the Std. Cirrus compared to the LS-8. Their US Handicaps respectively are 1.0 and 0.915. To me this would imply that the LS-8 is 8.5% "better" than a Standard Cirrus. (Better is not the best descriptor, but is meant to be a summary of glide performance and speed).

Lets assume that the two gliders mentioned above are flying at Best L/D.
LS-8: 43:1 at about 50 kts
Std. Cirrus: 36.5:1 at 50 kts
I calculate the difference in performance by looking at a multiple of the GR*V_(L/D). Since in this case the V_(L/D) is the same we can omit them, and just compute (36.5/43) which gives 0.849.

The numbers above are a bit crude because they are pulled from various sources online. Even the LS-8 data is "Calculated" and the tested data is slightly different. Looking at it from other sources:
LS-8: 43:1 at about 50 kts
Std. Cirrus: 38:1 at 50 kts
This still gives the LS-8 an advantage of 0.884.

In a final "base" example I will use some extreme numbers, degrading the performance of the LS-8, and exaggerating the performance of the Standard Cirrus:
LS-8: 42:1 at about 50 kts
Std. Cirrus: 38.5:1 at 50 kts
We finally arrive at an advantage of 0.917! (I take this as a "Factory New Std. Cirrus" flying against a "Buggy LS-8 without Gap Seals"?)

The above examples would be great if we flew contests while flying at Best L/D speed over three hour courses of 150 miles. The fact of the matter is we are frequently pushing MacCreedy "2" speeds on four hour courses that exceed 240 miles. (Let's compare the performance at 60 kts)

Since I don't have either of these factory polar curves to use, again, I am coming up with crude numbers, but I still think they speak volumes. These are a comparison of the L/D at a constant sink rate (2 m/s):
LS-8: 24:1 at about 92 kts (92*24=2,208)
Std. Cirrus: 22:1 at 86 kts (22*86=1,892)
Now we have a performance comparison at a more representative cruise speed in competition with a yield of 0.857 in favor of the LS-8. This means at a target MacCreedy speed I would expect the LS-8 to perform roughly 14% more efficient than the Standard Cirrus assuming the exact same pilot in the exact same point (Position/Altitude). This seems to be quite far from the 8.5% advantage given by the current Handicap List.

What phase of competition flight, often comprising nearly half the total time on course, have you left out? How much distance and speed is made during this phase? How different are the LS-8 and Std Cirrus during this phase? Does this affect your analysis at all :-)?

best,
Evan