REFLECTOR: Reflector Digest, Vol 87, Issue 124

[Kevin Baker]

Ahhhh  I wondered about that.
Very good explanation

I love all the knowledgable folks here on the Reflector.

I learned yet another thing today :-)

Thank you
Kevin Baker

.

On Jun 20, 2012, at 10:05 AM, Mark Magee <edjonesbrady at gmail.com> wrote:

> Hi Kevin,
> FULL FEATHER is best case scenario for any propeller driven aircraft that has lost power. We don't see it available so much in GA because it can require a hydraulic pressure reservoir. With a dead engine the windmilling is now the power source that turns the oil pump that controls the prop pitch. As pitch approaches FEATHER prop drastically slows down, as does oil pump, as does oil pressure required to continue pushing the blades to FEATHER. With no oil pressure reservoir (large and heavy) getting that blade those last 20-50 degrees to FEATHER becomes impossible as their is no more oil pressure left to push the hub. This is all assuming you haven't bled out your oil. Commercial turboprops will most likely have a hydraulic reservoir to get to feather, which will be the least drag/best glide or single engine performance profile.
> 
> Mark B. Magee
> N34XL XLFG
> Sent from IPhone 4
> 
> On Jun 20, 2012, at 9:41 AM, Kevin Baker <flykb at verizon.net> wrote:
> 
>> So to add to that thought..
>> What about the props that go to full feather when the engine quits...
>> I seem to remember a cs prop mfg that does that.
>> 
>> Thanks
>> Kevin Baker
>> 
>> .
>> 
>> On Jun 20, 2012, at 8:11 AM, Brooke Wolf <bwolf1 at tds.net> wrote:
>> 
>>> Not an expert Don, but I think you are right (others please chime in).  When you are out of oil you are SOL.  You are going to be landing closer to current position because without oil pressure, your prop resorts to fine pitch resulting in more drag.  But don't worry too much….spin that prop too long with no oil and you will end up with a stopped prop.  Less Drag!  Isn't that swell :>)   That is a good question about windmilling in course .vs. stopped in fine.  Don't know the answer.
>>> 
>>> Brooke
>>> 
>>> 
>>> 
>>>> There's one point missing from this conversation:
>>>> 
>>>> There are a lot of ways an engine can fail. Pulling the prop control back to improve the glide is only going to work in some of those failure modes. On an engine with a non-electric prop governor, pulling the prop control back is only going to help if A) there is oil in the engine and B) the engine is turning. If the failure is a result of no oil or the engine isn't turning, pulling the prop control back won't affect the prop. 
>>>> 
>>>> Which then brings up the topic of what is the drag difference of a stopped prop in fine (control forward) mode vs. windmilling in course (control back) mode?
>>>> 
>>>> Now discuss. :-)
>>>> 
>>>> -Don
>>>> 
>>>> 
>>>> 
>>> 
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