OverRun
9th Jul 2002, 09:41
737 takeoff roll and climb gradient - AEO ops normal
What is a typical takeoff ground roll length for a 737? I've got two cases in mind where the full performance engineering has been done to the various FAR 25 and Australian CAO 20.7.1B operating rules:
737-400 at a takeoff weight of about 58 tonnes which needs 1900m TORA (assuming 10 kts headwind, design air temperature, no obstacles, flat and dry runway, etc). This TOW was set for full pax, no freight, 2 hours flight.
737-800 at a takeoff weight of about 77 tonnes which needs 2500m TORA (assuming 10 kts headwind, design air temperature, no obstacles, flat and dry runway, etc). This TOW was set for full pax, no freight, 4 hours flight.
Now I've got the data for the engine-out and minimum climb gradient rules. My question is - ignoring all TORA, TODA, ASDA and climb gradient limitations - what is the typical takeoff ground roll for ops normal?
I dimly remember a rule-of-thumb that it is about two-thirds of the required TORA. For the required TORA of 2000m, the take-off roll might average something like 1333m. For the required TORA of 2500m, the take-off roll might average something like 1667m. Of course it will vary on every takeoff with technique, wind changes, noise, reduced thrust, performance degradation and all the other factors. But still - does anyone have a feel for a typical takeoff ground roll for a 737?
And since we're looking at what happens in an ops normal takeoff (as opposed to the minimum case), what would be a typical climb gradient to 500 or 1000 feet altitude. We've had discussion in this forum last year on "Engine Out Climb Performance". 4dogs wrote that "Most aircraft have to meet a minimum performance requirement of 6% AEO (all engines operating) (see CAO 20.7.4, FAR/JAR 23 and equivalent certification rules).
Now I know we're getting deep into the 'how long is a piece of string' analogy - and everything will vary with flap setting, noise abatement, weight, use of reduced thrust or not, temperature and wind, etc. But for a typical case, no noise abatement, no reduced thrust, reasonable temperatures, 10 kts headwind, the sort of weights I've got above, a bit of realistic airframe and engine degradation, etc - what is the sort of climb gradient that might occur up to 500-1000 feet altitude. I've got a rule-of-thumb from a deal that Front**r Airlines had with an airport in Amer**a, and had they agreed to perform to at least 8.6% whatever reduced thrust they set. Does that mean that 8½ percent is a typical gradient for ops normal?
Appreciate any thoughts
OverRun
What is a typical takeoff ground roll length for a 737? I've got two cases in mind where the full performance engineering has been done to the various FAR 25 and Australian CAO 20.7.1B operating rules:
737-400 at a takeoff weight of about 58 tonnes which needs 1900m TORA (assuming 10 kts headwind, design air temperature, no obstacles, flat and dry runway, etc). This TOW was set for full pax, no freight, 2 hours flight.
737-800 at a takeoff weight of about 77 tonnes which needs 2500m TORA (assuming 10 kts headwind, design air temperature, no obstacles, flat and dry runway, etc). This TOW was set for full pax, no freight, 4 hours flight.
Now I've got the data for the engine-out and minimum climb gradient rules. My question is - ignoring all TORA, TODA, ASDA and climb gradient limitations - what is the typical takeoff ground roll for ops normal?
I dimly remember a rule-of-thumb that it is about two-thirds of the required TORA. For the required TORA of 2000m, the take-off roll might average something like 1333m. For the required TORA of 2500m, the take-off roll might average something like 1667m. Of course it will vary on every takeoff with technique, wind changes, noise, reduced thrust, performance degradation and all the other factors. But still - does anyone have a feel for a typical takeoff ground roll for a 737?
And since we're looking at what happens in an ops normal takeoff (as opposed to the minimum case), what would be a typical climb gradient to 500 or 1000 feet altitude. We've had discussion in this forum last year on "Engine Out Climb Performance". 4dogs wrote that "Most aircraft have to meet a minimum performance requirement of 6% AEO (all engines operating) (see CAO 20.7.4, FAR/JAR 23 and equivalent certification rules).
Now I know we're getting deep into the 'how long is a piece of string' analogy - and everything will vary with flap setting, noise abatement, weight, use of reduced thrust or not, temperature and wind, etc. But for a typical case, no noise abatement, no reduced thrust, reasonable temperatures, 10 kts headwind, the sort of weights I've got above, a bit of realistic airframe and engine degradation, etc - what is the sort of climb gradient that might occur up to 500-1000 feet altitude. I've got a rule-of-thumb from a deal that Front**r Airlines had with an airport in Amer**a, and had they agreed to perform to at least 8.6% whatever reduced thrust they set. Does that mean that 8½ percent is a typical gradient for ops normal?
Appreciate any thoughts
OverRun