At 05:43 22 December 2018, Bob Gibbons wrote:
On Fri, 21 Dec 2018 16:02:33 -0800 (PST), Richard Frawley
wrote:

HI

Recently flew a 2008 Duo with the 5 bladed sustainer.

Started very fast and beautifully with very little height loss.

When it came to putting it away, it was, however, difficult to get it to
stop rotating.

Yes, put it half way retracted and yes, used the decompression to also
slow it down as advised. Only by reducing airspeed to close to stall and
holding it there, did it finally stop.

The days was hot. OAT at 3,000' was 32C.

Of interest (as it seems counterintuitive), why does the decompression
work to slow it down?

Regards

Richard

Richard, perhaps you skipped a few critical steps, or did them but
neglected to mention this.

1. Either turn off the ignition, or shut off the fuel, or both.
2. Partially retract the engine, perhaps 30 degress tilt.
3. Open the decompression valve for a few seconds and then CLOSE the
decompression valve. If you continue to hold the decompression open
the prop will NOT stop.
4. When the decompression valve is then closed the prop should stop
pretty quickly.
5. Complete retraction.

Hope this helps

Bob (19 years flying a Ventus C turbo)


I always find that pumping the decompression valve works best.

When the valve is closed the piston work like a bouncing spring, as it
moves towards TDC it uses the energy of the prop to compress the air in the
cylinder so slowing the props speed, as it goes over TDC the compressed air
is converted back into additional rotational movement of the prop. When you
pump the valve, depending on your timing, you keep removing the compressed
air from the system. This means the system has to use more energy to
re-compress the cylinder therefore slowing the prop faster than just
continually holding the valve open.

Works for me, Discus Bt and Ventus 2ct