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Dash_C.
06-30-2006, 12:32 PM
Since we will (hopefully) be getting the ability to have props hit by cannon rounds and such in BoB, I was wondering what kind of damage (historically) to expect. Did a cannon round to a propeller blade ever result in a catastrophic failure? What about engine damage from a lost blade? How common was damage to propellers from enemy fire?

Waldo.Pepper
06-30-2006, 12:38 PM
Common enough - a P-47 took a 20mm hit in a blade once. Made a neat little hole and the lucky pilot managed to make it home.

Tusseladden
06-30-2006, 01:05 PM
I read an Autobiography of Roald Dahl (the guy who wrote Charlie and the Chocolate factory yes). This book was called "Going solo" and is about his own service for the RAF in africa\greece. He once tells that he's chasing three junkers over a greek harbor when he sees tracer fire coming from the gunners. He didn't think he got hit, but when he touched down at base, the mechanic found a hole in his hurricane's propeller. Quite neat actually.

By the way, if a propeller gets hit, it will most likely produce less thrust if the aerodynamics are ruined. If a piece of a blade, or a whole blade falls off, it will shake the plane violently probably ruining the "drive shaft" and other engine parts. My best guess is that the engine will eventually jam somehow.

russ.nl
06-30-2006, 02:37 PM
I think if you lose a blade your proppelor axl will be of balance. If your proppelor will be spinning at 25000 rpm and looses, rufly, one quarter of its weight at one side. It gets so much unbalanced that it will breake loose.

Stackhouse25th
06-30-2006, 04:15 PM
A propellor that is improperly balanced will result in total engine destruction especially if were talking about greater chunks missing, and or complete blade seperation.

Mechanics propely weight and balance the prop before putting it back on. If it tilts too much left or right, they shave a little off (a gram or so).

A round especially 20mm will knock the s--- out of a prop. it will go through it? No, it will destroy it lol.

Sergio_101
06-30-2006, 05:08 PM
Loss of a blade from a prop will result
in rapid castrophic failure
of the gear box and or engine mounts
resulting in the loss of a prop (if your lucky)
or the partial or total seperation of an engine.

Typically a prop on a WWII era fighter rotates
at between 1200 and 1500 RPM. (give or take)
depending on throttle settings.

Prop strikes in combat were common.
Prop/blade seperations were also common.
Shooting your own prop from interuptor failure
was also not unheard of amongst planes
with such equipment.

Sergio

LW_lcarp
06-30-2006, 06:19 PM
Well here is an easy test to see what would happen. Go get a phillips screwdriver.(the one that looks like an X). Go to your ceiling fan thats in a room and take off a blade. Now turn on the fan to high speed. Record your results and you will now know what would happen to a plane missing a blade. http://forums.ubi.com/images/smilies/1072.gif

Dash_C.
06-30-2006, 08:06 PM
Originally posted by Sergio_101:
Loss of a blade from a prop will result
in rapid castrophic failure
of the gear box and or engine mounts
resulting in the loss of a prop (if your lucky)
or the partial or total seperation of an engine.

Typically a prop on a WWII era fighter rotates
at between 1200 and 1500 RPM. (give or take)
depending on throttle settings.

Prop strikes in combat were common.
Prop/blade seperations were also common.
Shooting your own prop from interuptor failure
was also not unheard of amongst planes
with such equipment.

Sergio

Whoa. I really hope this is modelled in BoB!

Imagine shooting at a 109 and watching the engine wrench itself from the aircraft. http://forums.ubi.com/images/smilies/16x16_smiley-surprised.gif

WB_Outlaw
06-30-2006, 10:29 PM
IIRC, none of the aircraft in the IL-2 series has the prop. bolted to the crankshaft. There is a large reduction gearbox between the prop and the crankshaft. I don't know if the gearbox is bolted to the crankshaft or not. It might be splined and just fit into the gearbox. This is a bit of a guess but if that's the case, I'd think the gearbox would come loose from the airframe before the engine would.

--Outlaw.

Choctaw111
07-05-2006, 06:10 AM
I saw a guncam film from a Bf110 firing on a B17 from behind using only 7.92 machine guns and making about 3 hits on the left inside propeller. There is no way of knowing which blades were hit but the propeller kept spinning like it was fine. Apparently rifle caliber bullets are not enough to tear apart a propeller with only a few hits.
If a prop blade is lost, however, there will be a catastrophic failure to the engine (on a direct drive) or the mount that the prop is on. One way or the other the prop will tear itself loose. I really do hope that this is modelled in BoB. We really haven't heard anything about BoB lately. Hope to hear something soon.

Sergio_101
07-05-2006, 06:56 PM
In this sim there are a number of planes
that have direct drive, or had it
in the early versions.

P.11
I-16
I-153
Gladiator
Early Brewster Buffaloes.
Early F4Fs

Note the designation for the Curtiss Wright R-1820
on later planes is, for example on a B-17G,
the GR-1820-97.

GR means it's geared.(Geared Radial).
Earlier versions of the R-1820 were not geared.

All high performance fighters of WWII were
of a geared design with roughly a 1.6: reduction.

It was VERY common in lower performance
planes to have no reduction gears.

Sergio

wayno7777
07-05-2006, 08:33 PM
Originally posted by Sergio_101:
Loss of a blade from a prop will result
in rapid castrophic failure
of the gear box and or engine mounts
resulting in the loss of a prop (if your lucky)
or the partial or total seperation of an engine.

Typically a prop on a WWII era fighter rotates
at between 1200 and 1500 RPM. (give or take)
depending on throttle settings.

Prop strikes in combat were common.
Prop/blade seperations were also common.
Shooting your own prop from interuptor failure
was also not unheard of amongst planes
with such equipment.

Sergio

One way or the other, that's the reason to feather the affected prop asap....

Sergio_101
07-06-2006, 02:35 AM
Originally posted by wayno7777:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Sergio_101:
Loss of a blade from a prop will result
in rapid castrophic failure
of the gear box and or engine mounts
resulting in the loss of a prop (if your lucky)
or the partial or total seperation of an engine.

Typically a prop on a WWII era fighter rotates
at between 1200 and 1500 RPM. (give or take)
depending on throttle settings.

Prop strikes in combat were common.
Prop/blade seperations were also common.
Shooting your own prop from interuptor failure
was also not unheard of amongst planes
with such equipment.

Sergio

One way or the other, that's the reason to feather the affected prop asap.... </div></BLOCKQUOTE>

I am aware of no single engined fighters
that had the ability to feather a prop.
That feature would be nearly useless.

The ability to feather is a drag reduction thing.
"Windmilling" propeller/airscrew uses more
power than a feathered prop.
In tests done by Boeing a frozen engine
with the prop not feathered had far less drag
than a windmilling prop!

The vibration from a lost blade is extremely violent.
I suspect in a single engine fighter the pilot
would be lucky to be able to touch anything
because of the vibration.

If a blade comes off, it's time to baill.

Sergio

IL2-chuter
07-06-2006, 03:40 AM
The effect of a bullet hole isn't necessarily as bad as stated here. I've seen quite a few pictures of holed props that kept right on running with the pilot thinking he had ignition problems or the like because of the engine roughness. I will also point out that I don't ever recall seeing a steel blade with a hole in it . . . hmmm. Steel blades were lighter and more apt to come apart due to being brazed. Also, as mentioned above, it's not likely the prop would be spinning more then 1800 rpm and could be as low as 1200 (maybe even less on a multi). Anyhow, here is but one pic of an aluminum (solid) blade, this on an Air Apache. Notice the prop wasn't feathered. Some pilots reported no hint of any problems before engine shutdown only to see the holed prop after dismounting. No doubt, however, there were other cases where blade tips were thrown leading to aircraft loss.



http://img.photobucket.com/albums/v366/IL2chuter/345thProp.jpg

danjama
07-06-2006, 04:03 AM
Originally posted by Sergio_101:
Loss of a blade from a prop will result
in rapid castrophic failure
of the gear box and or engine mounts
resulting in the loss of a prop (if your lucky)
or the partial or total seperation of an engine.

Typically a prop on a WWII era fighter rotates
at between 1200 and 1500 RPM. (give or take)
depending on throttle settings.

Prop strikes in combat were common.
Prop/blade seperations were also common.
Shooting your own prop from interuptor failure
was also not unheard of amongst planes
with such equipment.

Sergio

i was trying to read this as a poem http://forums.ubi.com/images/smilies/16x16_smiley-very-happy.gif

danjama
07-06-2006, 04:06 AM
Thought i'd add, i have seen pics somewhere (think Osprey book on 56th FG) of a P47 with a huge hole in it's prop that landed fine and dandy! I'll try to find the pic online.

Sergio_101
07-06-2006, 04:05 PM
Originally posted by danjama:
Thought i'd add, i have seen pics somewhere (think Osprey book on 56th FG) of a P47 with a huge hole in it's prop that landed fine and dandy! I'll try to find the pic online.

Yep, many times pieces of props have been blown off
or hole(s) and no one knew till engine shut down.
But shed a blade from a fighter, even a multi
engine plane and your in deep trouble!

On the other hand there have been instances
where a low altitude prop strike fails
to stop the plane.

Tens of thousands of fighters and millions
of sorties will result in some pretty strange
exceptions to the rule.

Sergio