RotorAndWing
Final Approach
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Rotor&Wing
Must have been making some power -- front prop is pretty warped.
Must have been making some power -- front prop is pretty warped.
If I'm not mistaken it's bent the wrong way. Prop strikes under power have the prop tips bent forward, no power has them bent back.
Looks like he had the rear engine feathered.
Really? Seems to me forward progress would bend 'em back.
Impressive structural integrity for the cabin. Looks pretty good. Don't know about the impact speed/angle, but not a bad advertisement for C337 survivability.
As explained to me: under power the propeller is moving faster than forward velocity and the pitch of the prop and force from the engine causes it to bend forward. No power then the forward motion of the plane bends them backwards.
Or, departure with known failed rear engine.....and any of the above.
If I'm not mistaken it's bent the wrong way. Prop strikes under power have the prop tips bent forward, no power has them bent back.
I really, really hope that wasn't the situation.
For all its warts I've always like the Mixmaster.
Thats an OWT.
I attended the Aircraft Accident Investigation Course at OKC. On the class about propellers that's the first myth they debunk.
Interesting. Is Lombardo's book Advanced Aircraft Systems incorrect, or is it a "not always the case" myth? See the section on "thrust bending force" on this page:
http://books.google.com/books?id=Ir...&resnum=1&ved=0CBIQ6AEwAA#v=onepage&q&f=false
The class I attended at the Transportation Safety Institute (which trains the FAA as well as NTSB Investigators) when we got to Propellers, the first thing the instructor did was dispel the myth of propellers always bend forward under power. We covered several case studies of both powered and unpowered and how to tell the difference.
I think the answer you're looking for here is that the blades typically bend forward if the prop was producing substantial thrust and backward if not when contact between prop and something more solid than air occurs but as R&W has stated this is not absolute, there are other factors. I can say that AFaIK a prop biting into asphalt, sod, or even water will likely bend forward under full power during a gear up landing or a ditching. And like R&W also stated, I expect that there are other reliable markers to determine if the power was on.You're not giving a complete answer. Did they say that propellers under power do not always bend forward, only sometimes, never bend forward without power, etc? I could see the possibility that under power does not always cause the tips to bend forward, but a windmilling or moderately powered propeller would never cause the tips to bend forward.
Think of it this way: you're moving forward at say 100MPH, but at full power your propeller tips are spinning at say 580MPH (76" @ 2,500RPM). The forward speed against the tips is really insignificant compared to the spinning force on the tips. The pitch of the tips is going to bend them forward, assuming that the contact rate is low, as would be in the case of a normal landing without the gear being down.
Here's what happened another time in a 337.
http://www.ntsb.gov/ntsb/brief.asp?ev_id=20020621X00957&key=1
Best,
Dave