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#1
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![]() "Roy Smith" wrote in message ... "Dudley Henriques" wrote: It could happen and did. Engine loss on a rear engine twin can be very deceiving, and it doesn't have to be a complete failure either. I would think it would be easy (at least from the engineering perspective) to display a big red warning light when the RPMs of the two engines differ by more than a certain percent. Did the 337 have anything like that? Ours didn't. Steam gauges only. EGT was the primary monitor on takeoff. Dudley Henriques |
#2
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On 2006-02-28, Roy Smith wrote:
I would think it would be easy (at least from the engineering perspective) to display a big red warning light when the RPMs of the two engines differ by more than a certain percent. Did the 337 have anything like that? They might not differ, though. In a partial power loss or perhaps a loss of an engine at a lower power setting (such as approach), the RPM on the engine not making proper power might still be the RPM selected by the prop lever. The only way you can tell for certain in all circumnstances which engine has failed from instruments is from the EGT (and in a partial power los on approach, even that might be hard). The 337 would probably have been much better with a pair of Garrett turboprops or PT6s with autofeathering props :-) -- Dylan Smith, Port St Mary, Isle of Man Flying: http://www.dylansmith.net Oolite-Linux: an Elite tribute: http://oolite-linux.berlios.de Frontier Elite Universe: http://www.alioth.net |
#3
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The non-success story is an intriguing question.
The type had some success in its military declinations (0-2A) during the Vietnam era. It is recognized and often used today as an engineering testbed for a variety of new designs and improvements, yet in its principal designated market it quickly developed an "ugly duckling" reputation which even today leads to depressed prices. There is not doubt it was noisy, inside and out. The high prop RPM and the fact that one of them was close to the rear seats contributed to this. Also, several models were anything but speed demons, giving lower TAS than some competing twins. I have heard (don't know the veracity of this) that cooling on the rear engine was inadequate, leading to a whole host of significant maintenance and reliability issues. We'll see how well Adam does with their new, spruced-up 337 (I know, I know - this airplane bears no similarity whatsoever to the ugly old mixmaster - yeah, yeah). For now, I see the 337 as one of the rare "deals" available on the market, the price/performance ration being favorable,in addition to the "safety" factor of a twin. Saftey is in quote here because most light twins are more dangerous than singles in the event of an engine failure, so the safety of a second engine is only theoretical - whereas in the case of the 337 it is real and useful. G Faris |
#4
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On 2006-02-28, Matt Whiting wrote:
Hard to imagine a pilot so sensory impaired that he or she can't detect the loss of 50% of their power, which results in lost of far more than 50% of most performance attributes. I'd really not want to fly with a pilot who was that out of touch with their airplane. I don't think that was necessarily the problem - imagine being just airborne on an obstructed and reasonably short airfield, then one of the engines quit. Although you feel the loss of thrust, it's not obvious which engine has actually failed from the yaw because there isn't any. Add to that the typical market segment for a 337 (people who percieve they won't be safe enough in a normal twin) and you're asking for trouble. The only way of figuring out which engine has quit short of pulling a throttle back and see if you lose even *more* power (which is ineffective if one engine is only losing partial power) is to look at the gauges. You might not even notice the loss of an engine if it happens on approach until you throttle up for a go-around and find up to 50% of your power is missing (if an engine fails on approach, the only indication may be a decreasing EGT - the windmilling prop may still make the same RPM and the manifold pressure does not change if an engine isn't actually combusting fuel). Even if one fails on takeoff, where the failed engine will almost certainly lose RPM you still have to look at and interpret the gauges which is a slower process (particularly if it's a high workload instrument departure) than 'dead foot dead engine'. The people who are liable to VMC roll a conventional twin are probably the same people who will stall a 337 while taking their time over trying to figure out which engine has quit. -- Dylan Smith, Port St Mary, Isle of Man Flying: http://www.dylansmith.net Oolite-Linux: an Elite tribute: http://oolite-linux.berlios.de Frontier Elite Universe: http://www.alioth.net |
#5
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#6
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"Dylan Smith" wrote in message
... [...] The people who are liable to VMC roll a conventional twin are probably the same people who will stall a 337 while taking their time over trying to figure out which engine has quit. I don't see how this is an issue. With centerline thrust, the pilot shouldn't NEED to know which engine has quit. The primary reason for knowing which engine has quit in a convential twin is so you can use the correct control inputs. With centerline thrust, you just keep flying the airplane. Why would any pilot spend any time trying to figure out which engine has quit on a 337? What are they going to do with that information, at least in the immediate sense? Pete |
#7
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"Peter Duniho" wrote in message
... I don't see how this is an issue. With centerline thrust, the pilot shouldn't NEED to know which engine has quit. Perhaps there is a need to feather the prop on the dead engine to cut drag? |
#8
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"Grumman-581" wrote in message
... Perhaps there is a need to feather the prop on the dead engine to cut drag? Ahh...good point, thanks. |
#9
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Sorry Duniho, the "dufus" guy was somebody else. My mistake.
Dudley Henriques "Peter Duniho" wrote in message ... "Grumman-581" wrote in message ... Perhaps there is a need to feather the prop on the dead engine to cut drag? Ahh...good point, thanks. |
#10
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You need to know hoe to identify the dead engine and feather
the correct prop, otherwise you're going down. In a conventional twin identification is holding heading with rudder, "dead foot dead engine" and the litany is CONTROL POWER (up) DRAG (gear and flaps) IDENTIFY VERIFY FEATHER FLY secure it In the 336/337 it isn't as easy or obvious which engine is sick or dead. -- James H. Macklin ATP,CFI,A&P -- The people think the Constitution protects their rights; But government sees it as an obstacle to be overcome. some support http://www.usdoj.gov/olc/secondamendment2.htm See http://www.fija.org/ more about your rights and duties. "Peter Duniho" wrote in message ... | "Dylan Smith" wrote in message | ... | [...] | The people who are liable to VMC roll a conventional twin are probably | the same people who will stall a 337 while taking their time over trying | to figure out which engine has quit. | | I don't see how this is an issue. With centerline thrust, the pilot | shouldn't NEED to know which engine has quit. The primary reason for | knowing which engine has quit in a convential twin is so you can use the | correct control inputs. With centerline thrust, you just keep flying the | airplane. Why would any pilot spend any time trying to figure out which | engine has quit on a 337? What are they going to do with that information, | at least in the immediate sense? | | Pete | | |
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