The propellers plane of damage ?

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Toobuilder

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Threw 4 inches off a Hartzel aluminum blade. Point if origin was a small nick at the TE (!). Resulting fracture was a jagged "S" shape, roughly aligned with the chord of the blade
 

Mcmark

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Didn’t understand your question. Look for yourself.
Fairly certain that the spinner departed and took out the blade.
Spinner and some of the blade recovered from golf course where it landed.
 

Aesquire

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From straight out from the hub in a plane to a shallow cone forward. That's the splinter zone.

it's a Really Shallow cone. The force pushing the blade forward is a tiny fraction of the inertial force pulling out.

Further out as the fragments or blades tumble they might be in any part of a parabolic arc. Which means a shed propeller part can land in front or behind the plane of rotation.

If you're parked in your driveway, just running the engine up, and lose a blade or just part of it, and it goes up, it can land hundreds of yards away.

But the danger is close and in plane. That's where it hasn't been slowed by friction etc. & can go through car doors or house walls like a knife thrown by a demigod.

So pay attention to where your prop plane is.

But for your question, directly in plane, is where I'd paint the red stripe. In your mind, at least.
 

Mad MAC

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The blade only really moves out of the disc plane once it has slowed down and drag relative to the forward motion of the aircraft becomes significant (hence a dent repair to the base of the fin on a beech 1900d from a prop blade impact after a gear up landing).
 

TFF

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Anyone who throws part of the blade is lucky the engine is still on. Shutting it down as fast as you can is all you can do. Reno planes run a cable around in case a thrown blade breaks the engine mount off so the engine will hopefully stay attached enough to land. I have heard of a few blades sticking out of cabins on n twins.
 

D Hillberg

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N131AT Bell 206 rolled over from a hover. At the hangar 100 ft away with my back turned saw a flash of black over our heads and a Ka BooM ... the student pooched the screw. That black streak was a 4 ft piece of blade that was found sticking up on the center line of runway 25. 100+ yards from the wreck. Another 7 foot piece was found a few months later south west of Bob's Café in a stream....That 7 foot piece during the crash flew over 3 R-22 helicopters hovering well behind the Jet Ranger. Surprised no one got killed let alone no injuries...
 

Vigilant1

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Obviously, a thrown prop blade or blade portion, even a lightweight wooden one, contains a lot of energy. Do certified aircraft or E-ABs attempt to armor or mitigate damage from thrown bits? I'm thinking of the tailbooms on a Cessna 337, cabins with occupants in the propeller plane, etc. It might not be practical to be 100% penetration proof, but some tough fiber (UHMWPP, etc) might be effective in preventing penetration and spreading the KE of a glancing blow or a tumbling fragment that presents more area to the structural part.
 

meglin1

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The torn blade has a huge destructive force.
At the very beginning of our production of propellers, we encountered several cases of separation of the blades. Two cases of cutting the elevator control cable on our aircraft were recorded. In both cases, the effectiveness of the horizontal tail was enough to perform a landing with a dangling elevator. After that, we installed a thick aluminum plate on the tail boom to protect the cables.
At the same time, the design of the blades was changed. There was no more destruction (25 years).
 

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Tiger Tim

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At high energy, the ones I’ve seen throw blades and pieces out radially in flight or in a forward cone when stationary on the ground. Interpolate as needed.
 

Topaz

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Have you thrown a propeller or part of one?
What shape is the plane of damage ? Is it directly in line with the propellers plane of rotation or does it curve forward or backward like in a bowl or or is it more cone shaped ?
The recommendation that I've seen is to exclude the pilot, passengers, and any critical systems from an arc 5° forward and aft of the plane of rotation of the propeller. Obviously many light twins and even turboprop airliners violate this recommendation, but that's what I've seen. Right off the top of my head I don't recall if that was in Raymer or Roskam, but if I find it later today I'll update this post.

UPDATE: Yeah, it was Raymer. In my third edition of Aircraft Design: A Conceptual Approach, it's listed at the top of page 263, in the "Propulsion and Fuel System Integration" chapter. Specifically:

Also, care must be taken to ensure that the crew compartment is not located plus or minus 5 degrees of the propeller disk, in case a blade is thrown through the fuselage.
Note that he said crew compartment not "passenger compartment." He's protecting the crew so that they can continue flying the airplane.
 

cblink.007

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I've shedded ice on proprotor blades in SLD icing condition testing and we all heard it striking the cabin...with the associated imbalance that came with it during the shedding cycle. The proprotor tips on the V-22 have a 9" clearance to the cabin in airplane mode. Amazingly enough, only the exterior paint was scuffed up with no evidence of skin damage (checked via NDI post-test). It was directly in the plane of rotation...and we were flying at 220 knots.
 

Pilot-34

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That is pretty amazing but I believe you. I was once northbound at 60 mile an hour with a brand spanking new cabover truck when I impacted a southbound pheasant. The impact shook and 80,000 pound truck . It impacted on the softest part of the cab the flat area between my knees and feet immediatelyinfrount of the steering wheel. The truck looks like it had been tarred and feathered with red then turned to brown tar.
I fully expected to find a significant caved in area but after washing and close inspection there was absolutely no damage to the structure or even the paint paint.
 

Twodeaddogs

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from my apprentice days, a colleague left a chuck key in a lathe and started it. First came the bang of it hitting the frame of the lathe and being thrown off,followed by the two cracks of it passing thru a window and then ramming itslef into a door 50 yards away, after having narrowly missed the head of a passing Flight Sergeant. We hid.
 

cblink.007

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from my apprentice days, a colleague left a chuck key in a lathe and started it. First came the bang of it hitting the frame of the lathe and being thrown off,followed by the two cracks of it passing thru a window and then ramming itslef into a door 50 yards away, after having narrowly missed the head of a passing Flight Sergeant. We hid.
"Trust Me, Gents; I know what I am doing" -Anonymous Warrant Officer before getting carted off to the medical"
 

Topaz

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That is pretty amazing but I believe you. I was once northbound at 60 mile an hour with a brand spanking new cabover truck when I impacted a southbound pheasant. The impact shook an 80,000 pound truck . ...
I can attest that a quarter-ounce Japanese beetle has a similar effect when striking the center of your motorcycle-helmet faceplate at ~120mph. :oops:
 

cblink.007

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I can attest that a quarter-ounce Japanese beetle has a similar effect when striking the center of your motorcycle-helmet faceplate at ~120mph. :oops:
I once heard that these things called "birds" can really prang-up an airplane if you encounter one in flight...
 

Pilot-34

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I had a neighbor that claims he once hit a rabbit while flying and acquaintance that. Claims to have flown through a Cloud of fish.
I once help released bags of 20,000 trout fingerlings into various pondsbut we were flying as close to the lake surface as possible so I do not think anybody would’ve flown through our cloud.
 
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