Talk:Critical engine

this entire article is very weak describing critical engine, and only lists ONE factor.

The P-38 Lightning had two critcial engines with counter-rotating propellers which turned in the opposite way to the usual directions. (a) Something odd must have been happening. (b) This article is clearly not the whole truth. 86.141.175.242 12:36, 8 February 2007 (UTC)

Please quote a reliable source that claims a P-38 has two critical engines. With contra-rotating propellers, it had no critical engine at all (or, to put it another way, both engines were equally critical).--chris.lawson 23:30, 8 February 2007 (UTC)

Chris- you are exactly correct! The P-38 DID have counter-rotating props, meaning, neither engine was critical- sustained level flight was achieved with either engine inop. My uncle is a WWII Vet and has numerous hours in the 38. Although, the artical is lacking, it's a good start. The post about the 38 having TWO critical engines is not correct.

Hi guys. I did a modification on the subject. Hope you like it.RobertoRMola (talk) 01:59, 6 June 2009 (UTC)

What would you think of the following modifications: (a) Change "Asymmetrical yaw" to "p-factor." Yaw is the effect, not the cause. P-factor is the cause of the yaw. (b) Clean up the use of the word "torque" in the "Asymmetrical yaw" section. The word's use is too similar to another factor affecting engine criticality, torque effect. Torque effect causes a roll toward the failed critical engine, not a yaw. (c) Expand on "Spiraling Slipstream." The current description is limited in information. (d) Add the missing 4th factor: "Torque Effect" --Rturaids (talk) 21:26, 29 September 2009 (UTC)

I was coming to the talk page to say that a plane with counter-rotating props has two critical engines, but you're all right - they are equally important and thus neither are critical. However it should be possible to note that there are two possibilities with a counter-rotating setup - the P-factor for both engines is either on the cockpit side of the engine (good) or on the engines' far side(bad). In the far side case, an engine failure requires the pilot to use more correction than in the close side case. Thus the optimal engine rotation pattern for a twin engine tractor configuration is a left-handed left-side prop and right-handed right-side prop. (Or so I believe) [Will]— Preceding unsigned comment added by 216.191.90.66 (talk) 18:31, 26 May 2011‎

The article says: "When one engine becomes inoperative, a torque will be developed which depends on the lateral distance from the center of gravity (C.G.) to the thrust vector of the operating engine multiplied by the thrust of the inoperating engine", which is inexact, it is not the distance to the Center of Gravity, but to the Center of Pressure, since the yaw developed is an aerodynamical effect, not a mass related one. The article also fails to mention that some airplanes have some angle built in the engines (pointing them slightly to the outside) in order to reduce the yaw in an engine out condition, the most famous being the DC-3 Amclaussen.— Preceding unsigned comment added by 192.100.180.20 (talk) 18:21, 26 September 2012‎

Center of pressure, and center of gravity, are important points on an aircraft, measured in the fore-and-aft direction. Both are often quoted as a percentage of the mean aerodynamic chord which is a measure of the wing chord (measured in the fore-and-aft direction). It is true that the center of gravity is usually a small lateral distance either side of the fuselage center-line but this is usually only of significance in helicopters. Center of pressure is located in the fore-and-aft direction, on the center-line of the fuselage, or the wing. The center of pressure moves a small lateral distance either side of the fuselage center-line when the aircraft rolls, such as when the ailerons are moved or the aircraft is placed in a sideslip. Asymmetric thrust develops when the thrust axis is displaced laterally from the drag axis. With all engines operating, drag acts along the fuselage center-line, through both the center of gravity and center of pressure. Our statement could be made most accurately by saying a torque will be developed which depends on the lateral distance from the drag axis to the thrust vector of the operating engine ... When one engine is inoperative it usually develops extra drag, especially if the engine is driving a propeller and the propeller is not feathered, and this extra drag causes the drag axis to move from the fuselage center-line towards the inoperative engine. This reinforces the merit in saying asymmetric effects are dependent on the distance from the thrust vector of the operating engine to the drag axis.Dolphin (t) 23:21, 26 September 2012 (UTC)

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