On Fri, 24 Aug 2018 14:00:59 -0700, Bob Kuykendall wrote:

This isn't about electric versus unpowered. It's about the necessity of
doing this with a crewed vehicle. There is nothing in any of those
arguments that supports carting two humans and several hundred pounds of
life-support infrastructure around the sky.

Sure, but would you be happy to tow an autonomous glider above the lower
stratospheric boundary?

I'm sure that there are valid arguments for having humans aboard so they
can respond adaptively and innovatively to any flight or scientific
situation that might arise. I simply don't buy the idea that doing so is
best or even lowest-cost option. I think that a UAV, or a cooperative
swarm of UAVs, or even a series of balloon-dropped UAVs, could do the
planned research with a risk/reward ratio about an order of magnitude
better.

Isn't there a fairly radical bit of mission redesign going on? IIRC
Fossett and Einevold were set up the Perlan because they could and to
push the record up as high as they could, with a bit of science thrown in
as well, but now DrDan Johnson (and Airbus) are saying that was all very
well then but NOW the project is all grown up and concentrating on
Serious Meteorological Science.

You may well be right than an unmanned vehicle can do it cheaper if the
mission was designed that way from the start. All I'm really saying is
that wasn't how it happened.

Judging by an article by Jean-Marie Clement in Sailplane & Gliding (Dec/
Jan 18 p40) the Perlan Project may have missed the boat for setting a
properly high record. M. Clement says that climate change has stretched
the Andean wavelength by causing and increase in wind speed, so it is no
longer in phase with the mountain topography. This weakens wave lift
while the increased wind speed has also reduced the duration of weather
cycles. He talks about having to accept 2-3 m/s wave climbs in 2017 where
a decade ago they'd have had 5-8 m/s, but adds that the vertical velocity
in hydraulic jumps wasn't affected though the jumps may have become more
frequent.


--
Martin | martin at
Gregorie | gregorie dot org