Comparison of glider classes at Uvalde...

The evidence is really undeniable. What has been driving the 18m and open class, is the perception that the bigger spanned classes are far superior than what they in fact are.

The 15m other sailplane builders still have no answer to the Diana-2. Maybe the Duckhawk is an answer - we'll see. Diana-2 has sold poorly IMHO, because of perception.

Maybe we should replace wingspan with wing aspect ratio, when looking at the layout. The Diana-2 and now the Duckhawk, for me, seem to indicate that this is the more important metric. In these two designs, the low weight is used advantageously in an aerodynamic sense to produce a larger aspect ration wing with a smaller wing areas, than would otherwise be practical.

Wing profiles today, show little differences from one to the other.

In the analysis, it should be noted, that the EB29 can be flown in a 25.3M configuration, reaching about 58kg/m wing loading.

On paper the larger ships should have been faster, but they're not. So we are not taking everything into consideration.

Speculating here, does it take longer to accelerate a long spanned ship, due to the higher profile drag, through sink or upon thermal exit? If so, they would be flying slower than the smaller ships through sink.

One point that I think has been missed is that I believe the open class was
tasked with longer tasks than the other classes during the WGC. That would
make their final glide a smaller percentage of their entire flight - which
would make their overall speed a bit slower that it would be if they flew
the same length tasks that the 15m and 18m ships flew.

Also, I image the difference in speeds would be greater at a soaring site
with weaker lift than found in Uvalde. The 21m and 23m ships and their high
wing loadings seem tailor made to Uvalde's very strong soaring conditions.

Paul Remde