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#Post#: 17--------------------------------------------------
ON ENGINE RUNAWAY
By: Flying Dutchman Date: June 3, 2020, 12:06 pm
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I like the concept - had something similar in mind.
Was thinking along the lines of if separation (your table edit
and die rolls seem good) it could result in either No effect
(harmlessly falls away in this case), a Front Centre Section,
or Wings table hits (that way it can hit either adjacent engine,
fuel tanks, wing roots, wing bomb cells, etc...) - at either 2,
3 hits. You leave decent room to survive separation it looks
like, probably help save frustration from the more vague 6 is
death sentence.
Let me make sure I understand the separation sequence correctly
- so, prop out unfeathered let's say zone 3. You roll 1d6 - on a
1-2 a separation occurs? If I roll a 3, then next zone I roll
again, but it occurs on a 1, 2, or a 3? and then a 1-4 the next
zone, until separation does eventually occur?
I like it - seems to me to simulate the nature of the problem,
much better than game does out of the box, no doubt.
On Sat, May 30, 2020 at 10:31 AM bob marley <robocop01@gmx.net>
wrote:
Old topic, new title as an attempt to structurize...
So, lets check crazy engines misbehavin.
Did I hear Avro Manchester?
(The Manchester was a 2 engined plane with infamously unreliable
Vulture engines, and often could not maintain altitude on
1 engine even IF the other was feathered.)
I checked Kirbys exellent "Avro Manchester, legend behind the
Lancaster" and found a case. (see attachment scan RUNAWAY)
So from the book:
1. Mentioned full fine position means blade angle 90 (!) degrees
to incoming airflow. Max drag situation.
2. Cutting fuel to engine possible (so stopping it).
3. Engine killed itself, which was NO catastrophic event
directly, and prop remained windmilling.
Not in this case evident, (because flying over the UK gave
plenty of landing opportunities) but I claim that (an a/c able
to maintain height):
had they flown on, eventually due to failing lubrication the
prop shaft would heat up so much that the prop breaks away
randomly.
I read examples of that, even of entire engine block falling of
wing, but cannot remember where...(a.o. a B17, but has same
tech)
Just as a possible take on that:
Taking table L-6:
d) roll 1D6:
1-5: feather, eng out.
6: engine effectively out, prop not feathered: roll for prop
separation (and consider feathered) after rolling 1D6 each zone:
-this zone: 1,2 (else continues windmilling, drag penalty))
-after that add 1 to probability each zone (e.g.
1,2,3,4=separation in 2 zones from start)
-when separation takes place, roll for prop/engine debris:
1-4: prop falls away harmlessly
5: prop hits a/c:
if an inner eng: prop hits FRONT CENTER fuselage:
treat as 3 hits.
if an outer eng: prop hits inner engine: 1,2 sfd /
3+=treat as eng hit.
6: prop may hit a/c:
if an inner eng: prop hits outer engine: 1,2 sfd /
3+=treat as eng hit..
if an outer eng: prop falls away harmlessly
Rob.
Flew around with props.
Was no "runaway engine" threat on constand speed, piston planes
I flew. (Cessna172, piper arrow, piper seneca)
A turbo-prop Bae Jetstream 31 without auto feather/eng fail on
takeoff very hard to control, but can be done.
Engine failure in cruize with these planes all ugly if no
feather, but doable.
Its no WW2 tech, but in principle comparable.
My take: there are the engines, and they work. If not, you shut
them down and feather. (fuelcutoff)
Windmilling means prop governor fails to feather. (A feathered
prop stands still in the wind, good thing, no friction, minimum
drag.)
Then blade angle still more than 0 degrees, causes uncontrolled
windmilling and drag.
Its a pretty complex topic.
I already described what I know can happen to heavy bombers, I
wil not exclude other effects if fuelcutoff fails or some other
unusual condition.
So that would be speculative...
Gesendet: Freitag, 29. Mai 2020 um 20:01 Uhr
Von: "David Damrel" <david.damrel@gmail.com>
An: "bob marley" <robocop01@gmx.net>
Cc: "Harvey T.Dearden" <htdearden@tdsl.org.uk>, "simon haines"
<horsarider@gmail.com>, "GLENN SAUNDERS" <gcsaunders@shaw.ca>,
"Christopher Schall" <airborne@zoominternet.net>, "NIGEL HODGE"
<nsrj@btinternet.com>, "Richard A Martin" <martinrick@msn.com>,
"ronez@freenet.de" <ronez@freenet.de>
Betreff: Re: Re: RE: Fuel Management Rules
I don't know where we can find specifics on this one (maybe I'm
not looking hard enough) - I think most windmilling these days
would occur on smaller general aviation type aircraft, and I
don't think the effects would be anywhere near as threatening as
on a medium or heavy bomber. Maybe this will require other sets
of die rolls. If you roll a 6 initially then perhaps the
situation worsens, but is not immediately catastrophic. Maybe
you can then roll to see if prop breaks and damages either
adjacent engine/wing (roll on wing damage table), or fuselage -
maybe roll (1 or 2 shell hits) on front centre section?
Maybe also have a reduced capacity for range due to extreme
vibration - perhaps the crew can reduce power, spend two turns
per zone, and have to roll potential worsening per zone.
Something to those effects?
Just some thoughts to bounce, hopefully somewhat
aerodynamically/physically sound. =D
On Fri, May 29, 2020 at 1:46 PM bob marley <robocop01@gmx.net>
wrote:
Well,
Happened to USAAF bombers as well (logically), check google.
Perhaps a result including "death by vibration" (if you find a
case) and "the prop launch" (Ive seen cases).
Rob.
Hmm. Whereas the game has it as immediately catastrophic...
Harvey T. Dearden
(mobile phone transmission)
From: simon haines <horsarider@gmail.com>
Sent: Friday, May 29, 2020 2:11:55 PM
To: Harvey T.Dearden <htdearden@tdsl.org.uk>
Cc: bob marley <robocop01@gmx.net>; David Damrel
<david.damrel@gmail.com>; GLENN SAUNDERS <gcsaunders@shaw.ca>;
Christopher Schall <airborne@zoominternet.net>; NIGEL HODGE
<nsrj@btinternet.com>; Richard A Martin <martinrick@msn.com>;
ronez@freenet.de <ronez@freenet.de>
Subject: Re: RE: Fuel Management Rules
Yes it did, major damage obviously, but yes.
On Fri, May 29, 2020 at 2:10 PM Harvey T.Dearden
<htdearden@tdsl.org.uk> wrote:
Did the plane survive?
Harvey T. Dearden
(mobile phone transmission)
From: simon haines <horsarider@gmail.com>
Sent: Friday, 29 May 2020, 12:11
To: bob marley
Cc: Harvey T.Dearden; David Damrel; GLENN SAUNDERS; Christopher
Schall; NIGEL HODGE; Richard A Martin; ronez@freenet.de
Subject: Re: RE: Fuel Management Rules
Interesting. And one plane when the propeller did come off, went
through the fuselage and destroyed the engine on the other wing.
Simon
On Fri, May 29, 2020 at 11:38 AM bob marley <robocop01@gmx.net>
wrote:
"A feathered prop would introduce drag"
No.
See Davids research, quite spot on...
What happens is that the engine will vibrate and start
windmilling, doing all kind of nasty things (certainly up to
structural failure for smaller aircraft) but finally, after some
time the prop shaft/axis metal would heat up to the point of
failure.
The prop will detach from the engine, most likely spinning away
violently in a random direction, hitting anything in its path.
Its the reason why I suggested before that making the runaway
engine result into some fuel result not a good thing.
So there you go:
-Might hit other (so far) good engine i.c.o. 4 engined plane.
-Might hit fuselage, depending on a/c type around/behind pilot
and F/E.
-Might mercifully disappear in the black night ending up as
nunchaku on you roof...
Rob.
Gesendet: Donnerstag, 28. Mai 2020 um 19:29 Uhr
Von: "Harvey T.Dearden" <htdearden@tdsl.org.uk>
An: "David Damrel" <david.damrel@gmail.com>
Cc: "simon haines" <horsarider@gmail.com>, "bob marley"
<robocop01@gmx.net>, "GLENN SAUNDERS" <gcsaunders@shaw.ca>,
"Christopher Schall" <airborne@zoominternet.net>, "NIGEL HODGE"
<nsrj@btinternet.com>, "Richard A Martin" <martinrick@msn.com>,
"ronez@freenet.de" <ronez@freenet.de>
Betreff: RE: Fuel Management Rules
Don’t think so – it is the spurious feathering of the prop that
causes the prop to be unloaded – the engine then accelerates
because of the reduced load. A feathered prop would introduce
drag but I’m sceptical whether this would be significant enough
to cause loss of the aircraft on a 4-engined bomber?
H.
From: David Damrel <david.damrel@gmail.com>
Sent: 28 May 2020 18:12
To: Harvey T.Dearden <htdearden@tdsl.org.uk>
Cc: simon haines <horsarider@gmail.com>; bob marley
<robocop01@gmx.net>; GLENN SAUNDERS <gcsaunders@shaw.ca>;
Christopher Schall <airborne@zoominternet.net>; NIGEL HODGE
<nsrj@btinternet.com>; Richard A Martin <martinrick@msn.com>;
ronez@freenet.de
Subject: Re: Fuel Management Rules
Hmm, well - in the case of runaway, I think it's solely down to
whether or not the propeller can be feathered or not. Check this
excerpt out from a book specifically on the evolution of props.
So, maybe a reduction in throttle/speed would buy the crew some
time, but the plane probably wouldn't be able to sustain much
more distance trying to operate normally with a renegade
prop/engine.
On Thu, May 28, 2020 at 9:35 AM Harvey T.Dearden
<htdearden@tdsl.org.uk> wrote:
The more I think about this runaway engine thing the more
troubled I am. We have established that the FE or another could
isolate the fuel (or cut the ignition?). It is described in the
pilot notes as ‘prop not feathered – out of control’ but it
seems it is the fact of being spuriously feathered that is the
problem. If the engine did runaway I can certainly imagine it
being wrecked – but abandon the aircraft? With 1 in 36 engine
hits?
I acknowledge that I write in ignorance of the specifics…
I have it in mind to add this roll instead to the Engine Hit
Fuel Leak probability in the FM rules…
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