On Tuesday, September 20, 2016 at 9:01:26 PM UTC-4, Soartech wrote:
or fantasy of flight?
On page 52 of the September issue of Soaring magazine Jim Payne is listed as having flown an out and return course of 300 km at an average speed of an amazing ground speed of 189.62 MPH ! Can someone please explain how he did this when the Vne of the Arcus M is 174 MPH. It seems to me the only way to do this is to somehow fly (at Vne the entire flight),downwind, on both out and return legs.

A rule of thumb under standard conditions is about 2%/thousand feet increase in True Airspeed. So, if you're indicating 100kts at 10% feet you're actually doing closer to 120kts over the ground in still air.

Now, the problem kicks in with flutter and aeroelasticity, so the VNE (indicated) decreases with altitude in most gliders. I'll leave it at that, since it's been more than 30 years since my last problem set on that topic :-)

P3