Peter wrote:
I used to have an instructor who used to stop the prop, on a C150/152. It took about 45 degrees pitch-up and a deep stall. He used to do with with lots of pleasure flight trial lesson customers too
Yep, I recall being in the back seat once!
I also recall in my intial Mep the mandatory prop. stop, except neither of us could restart it. Oh well.
In MEPs it is now only a prop feather for renewals, which is probably a good thing.
It is of course common aerobating most things without injection and really par for the course, but I was never very keen. I would far rather an injected engine for all such work.
Peter wrote:
What is the PA46 POH data on fully-coarse versus stopped?
The POH only has coarse, and does not specify if the prop is stopped or not; however the experience I quote in the OP suggests the figures given in the POH (27 minutes and 48nm from 20k feet at ISA) are way too optimistic if you don’t stop the prop, and even worse that with the engine stopped/failed you can’t bring the prop to coarse. Of course in the turbine version it’s very different.
dirkdj wrote:
The difference between a windmilling engine with the prop fully fine and fully coarse is dramatic. You have to experience it to believe it.
I haven’t tried it, but considering the braking effect when you the put the prop into max rpm on approach, I do believe it.
The difference between a windmilling engine with the prop fully fine and fully coarse is dramatic. You have to experience it to believe it.
I used to have an instructor who used to stop the prop, on a C150/152. It took about 45 degrees pitch-up and a deep stall. He used to do with with lots of pleasure flight trial lesson customers too 
Of course the prop is likely to be user-stoppable only if the engine has not seized So this is really a fuel system issue.
I am not sure I would necessarily want to stop the prop, because you lose the alternator(s) and especially in a PA46 which might glide for some 20 mins from a typical cruise altitude that will take out a chunk out of your battery life (whatever it actually is). I would try it only if I was really trying hard to extend the glide.
What is the PA46 POH data on fully-coarse versus stopped? I found, during the FAA CPL checkride (no kidding; the DPE was keen to teach me stuff) that you get about another 30% glide distance with it coarse, relative to fully fine.
Only did it once, in a Piper PA-28-140, at 3000 ft above an airfield. A full flap normal stall was not slow enough to stop the engine. An accelerated stall into a nose-high attitude with a low-g, very-low-speed stall was required.
I would like to know if it could be restarted by diving, but I would not like to try. Forcing an engine from standstill instantly up to high RPMs seems unpleasantly abusive, even if the engine is still hot.
The rate of sink was clearly significantly reduced. In a real engine-out emergency, I would do that if at altitude in VMC. Of course, any vacuum-driven gyros will start spinning down.
(I do it all the time in the Grob TMG – just stopping the prop by feathering the prop: it improves glide ratio from around 1:18 to around 1:25. An airstart can be performed gently by taking the prop very slowly out of feather.)
For wind-milling with constant-speed props, I have found great differences between aircraft regarding the effect on pulling back the prop lever. On the C177RG, it makes a world of difference. On my Piper Dakota, I cannot tell any effect. Those two fly in very similar speed regimes, so other factors are at play (like low-rpm-governing-limit and coarse-pitch-stops).
I did shut down and stopping the prop in a touring motor glider L-13SE few times, you need to slow down almost to stall. Once stopped, you can speed up, it will not start moving again unless you are well above typical cruise speed.
All above was intentional. When it comes to real engine failure, there are better things to do – I had one earlier this year somewhere around 2000 ft above and close to the airport and the prop stopped only during flare….
In 1964, I was told a propstart was needed for a CPL, and therefore was routinely done by Wiltshire School of Flying at Thruxton. In a Tiger Moth, with no starter. It stopped without stalling, and re-started with a very steep dive. Instructor was ex WW1, too old for front line aircraft in1939.
I don’t remember a rudder kick, but I’ve been told that is recommended to restart prop movement.
I’d try to keep the prop moving while trying fuel combinations to get the engine running.
I did it once in the Jetprop (with Travis) , he shut the engine down at 12000ft above a very long runway and we glided around for more than 5 minutes at
90kt IAS, prop was feathered and stationary, it felt like being in a glider, sink rate was very low.
Part of the excercise was to demonstrate a restart, I definately would not intentionally try it on my own!
Thanks.
