PPRuNe Forums - View Single Post - Debate over Mcrit and Mach Trim
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Old 2nd March 2007 | 00:41
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gimmesumviagra
 
Joined: Mar 2007
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From: on the beach
Buying into this Suicidal discussion:

Further to jaguar Pilot:
'Super Critical' was designed by Airbus and is noticeable on the A330/340 wing (maybe 777 - not sure). This permitted some airflow over the wing to be supersonic without resulting in an unacceptable rise in Drag.
This results in a higher MCrit, resulting in a higher Mmo/Vmo

In the older generation T-tail Jets (B727/DC9) there was a Mach Tuck effect. At high Mach Nos the nose tended to pitch down, and nose-up pitch trim was introduced to compensate.

Not so noticeable on new generations.

While flight testing our B767 SIM at high Mach No, I have observed:
1. Initially Auto-throttle response to compensate (as per systems);
2. A Nose-up pressure (maybe aerodynamic or perhaps some nose-up stab trim) [perhaps someone from Boeing can enlighten me]
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