Multi-jet engines not "handed"
Quote from BESTGLIDESPEED:
It comes from the " ace the tech. pilot int. " book that most of all of us know way too well , therefore, canīt trust it much either. :
" there is NO critical gas turbine engine because the engines are positioned simetrically with opposing revolution direction "
[Unquote]
You are right; sounds rubbish to me. The engines are indeed symmetrically positioned, but to suggest they are ever "handed" (like some high-performance twin-piston-engine fighters were in WW2) is wrong. But it doesn't matter (we are told) because the slipstream from a jet engine, even a big-fan engine, does not rotate like the slipstream from a propeller.
I am not entirely convinced when considering some twin-jets, with today's high-bypass-ratio fan engines. The slipstream definitely assists rudder at low IAS on the A320, for example. [I'm talking about the CFM-56 engine, with the short fan duct. Not sure about the V2500 engine.] Whether it is rotating, I don't know. If the slipstream is rotating, it might result in some difference on the lines of a propeller-driven twin.
In the propeller (airscrew) case, the rotating slipstream impinges on the side of the fin (sorry, vertical stabiliser), giving a yawing effect. If the propellers are not "handed", the rudder is less effective in one direction than in the other. In any engine failure case, the resulting yaw has to be corrected by rudder in the direction of the live engine.
There is definitely a critical jet engine, as many have now posted, due to a crosswind effect. And I think we all agree that, if everything else is equal, the upwind engine is the critical one.
[By the way: in case anyone thinks I have lost interest in the subject of "weathercocking versus drift" he/she will be disappointed later...
Been busy ransacking the house for material in connection with Lodems's above post on his historic B707 accident.]
Last edited by Chris Scott; 29th Feb 2008 at 00:44.
Reason: To specify CFM-56 in the A320 case.