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Minimum acceptable self-launch climb rate
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April 30th 20, 03:48 PM posted to rec.aviation.soaring
Jonathan St. Cloud
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Posts: 1,463
Minimum acceptable self-launch climb rate
On Thursday, April 30, 2020 at 7:15:04 AM UTC-7, Dave Walsh wrote:
At 13:17 30 April 2020,
wrote:
38:1 -- is that with the jet engine extended, gear retracted?
Yes- gear retracted, engine extended but not running.
The biggest cause of the terrible performance of the Arcus M
with the prop
=
and pylon up is the fact that the two huge 6 ft. long doors
remain open
and=
the big engine bay and the rest of the hole in the fuselage gives
all
thos=
e draggy little air molecules a place to run around before finally
jumping
=
out.
The ASH-26E appears to have smaller doors and a smaller
engine bay, and
pos=
sibly less drag because of this.
And for those of you who still don't believe, 495 fpm is 8.25 feet
per
seco=
nd. 60 knots is 101.27 feet per second. 101.27/8.25 =3D
12.275.
Just out of interest the electric 20m Antares20E which has a
"book" L/D of 56:1 does 30:1, engine out and prop windmilling,
gear retracted. The main engine doors are closed when the engine
is erected. The prop is stopped by the "electronics", if it throws a
wobbly the pilot has no way to stop the prop. The prop is 2m
diameter, two blades. The engine is direct drive to the prop so the
engine would have had to seize up for the prop to be stopped &
erected. The circuit & landing are a bit of a non event, rather like a
K13.
I've never experienced "plummet mode" in an Arcus; the
DG400/800 plummet rather well.
Dave Walsh
Someone please correct me if I am wrong but I believe only 4 Arcus E's were sold and one of those was written off in an accident?
Jonathan St. Cloud
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