PPRuNe Forums - View Single Post - Indonesian aircraft missing off Jakarta
View Single Post
Old 30th Nov 2018, 18:27
  #1843 (permalink)  
tdracer
 
Join Date: Jul 2013
Location: Everett, WA
Age: 68
Posts: 4,420
Received 180 Likes on 88 Posts
Originally Posted by silverstrata


The -400 had 24,000 lb thrust.
The -800 had 27,000 lb thrust.
The max-8 has 28,000 lb thrust.

I call that a steady increase in thrust, with a steady increase in pitch up moment, when applying full power at low speeds. Besides, the Bournemouth incident, where a 737 pitched up to 47 degrees, demonstrated that even the NG series had more thrust-pitch moment than the elevator had aerodynamic pitch moment, when at slow speeds.

Silver

Those numbers are for "Sea Level Static" thrust. Thrust in-flight is different. On large turbofan engines, the net thrust 'lapses' (decreases) with forward speed - the higher the bypass ratio, the greater the lapse with speed (very basically, the ram drag on the inlet goes up faster than the gross thrust generated by the fan exhaust).
I don't have any specific information for the MAX, but I suspect you'd find that, because of the much higher bypass ratio on the Leap, at ~250 knots, the net thrust of the NG -800 and MAX -8 are much closer than the SLS thrust.
tdracer is offline