Andreas Maurer wrote on 9/19/2019 12:11 PM:
On Wed, 18 Sep 2019 15:16:31 -0700, Eric Greenwell
wrote:


I've never had anyone flying the usual PIK, DG, ASH, and Ventus self-launchers
mention plummeting or reduced control authority to me, but I'm sure there must be
some like that. What gliders have this plummet/control authority problem, and how
bad is the plummet (same as half spoiler, full spoiler, etc), and reduction in
control?

Arcus M - you ought to be able to find a operating handbook online.
WIth extended power plant the L/D decreases to 13/1 and minimum sink
rate to 443 fpm.

So far I've seen two DG-400s crash that were trying to land with
extended power plant and didn't reach the runway.

That's one, perhaps, but 443 fpm doesn't seem like "plummeting" to me. I'm
surprised it's so poor mast up, as I've read the PIK20E is 15:1 with the mast up,
and that's only a 15 meter glider with the engine on the mast, unlike the buried
engine in the Arcus M. How does mast up compare to half or full spoiler, and is
that measured with the gear down?

Here's another data point: the last time I flew my ASH26E, I stopped the engine
while thermalling, but did not lower the mast. The glider continued to climb at a
reduced rate in the thermal. Note that the mast is always left half extended to
cool for several minutes after an engine run, and the thermal climb is not
noticeably improved when the mast is finally fully retracted. So, NO plummet mode
on the 26E, and really don't think it's that much different from an 18 M Ventus or DG.


--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorg...ad-the-guide-1
- "Transponders in Sailplanes - Dec 2014a" also ADS-B, PCAS, Flarm

http://soaringsafety.org/prevention/...anes-2014A.pdf