25-08-2017, 01:57 PM
(This post was last modified: 26-08-2017, 02:38 AM by Shaun Patterson.)
Despite having the correct fuel tank sizes and a fuel flow scalar of 1, the default 737 consumes fuel almost twice as fast as it should. I've seen many people modify the fuel flow scalar to combat this, but this does not adjust the predicted fuel usage in the nav log/flight planner. To combat this, I've managed to fix the issue.
The thrust specific fuel consumption is how much fuel is consumed for a given amount of thrust... and is wayyy off; 0.6 in the aircraft.cfg. This is as fuel efficient as early low-bypass turbofans like the Rolls Royce Spey and JT8Ds. In other words, it's a guzzler!
The real consumption is much lower, but differs slightly on the thrust rating you choose.
The 737-800 has three engine options, each with different weight restrictions. Choose one and stick to it.
//----------------
CFM56-7B24 (this is what the default 737-800 has, with a slightly lower fuel consumption than other variants, best to use on shorthaul flights with full passenger loads from runways exceeding 8,000ft)
[weight_and_balance]
max_gross_weight = 155500
empty_weight = 91300
[turbineenginedata]
rated_n2_rpm = 14460
static_thrust = 24200
thrustspecificfuelconsumption = 0.37
//----------------------
CFM56-7B26 (The middle ground. Probably the recommended option. Lots of extra thrust and payload for all your needs.)
[weight_and_balance]
max_gross_weight = 172500
empty_weight = 91300
[turbineenginedata]
rated_n2_rpm = 14460
static_thrust = 26300
thrustspecificfuelconsumption = 0.38
//-------------------
CFM56-7B27 (an extra 1000lbs of thrust and minimal payload increase. I would only recommend this option for short field performance or 'hot and high' operations.)
[weight_and_balance]
max_gross_weight = 174200
empty_weight = 91300
[turbineenginedata]
rated_n2_rpm = 14460
static_thrust = 27300
thrustspecificfuelconsumption = 0.38
//---------------------
All fuel requirements in nav logs should be correct now. Remember to added an hour reserve and 15 to 25 percent extra for taxi and climb.
As well as this, I plan on writing up a more advanced checklist and performance page for the aircraft to include takeoff n1 settings and the likes. Perhaps some vc/panel fixes too. I'll continue to update specs for other default aircraft. Of course these specs can be added to freeware aircraft too, as long as you check the fuel_flow_scalar is equal to 1 (I know POSKY aircraft are slightly above).
The thrust specific fuel consumption is how much fuel is consumed for a given amount of thrust... and is wayyy off; 0.6 in the aircraft.cfg. This is as fuel efficient as early low-bypass turbofans like the Rolls Royce Spey and JT8Ds. In other words, it's a guzzler!
The real consumption is much lower, but differs slightly on the thrust rating you choose.
The 737-800 has three engine options, each with different weight restrictions. Choose one and stick to it.
//----------------
CFM56-7B24 (this is what the default 737-800 has, with a slightly lower fuel consumption than other variants, best to use on shorthaul flights with full passenger loads from runways exceeding 8,000ft)
[weight_and_balance]
max_gross_weight = 155500
empty_weight = 91300
[turbineenginedata]
rated_n2_rpm = 14460
static_thrust = 24200
thrustspecificfuelconsumption = 0.37
//----------------------
CFM56-7B26 (The middle ground. Probably the recommended option. Lots of extra thrust and payload for all your needs.)
[weight_and_balance]
max_gross_weight = 172500
empty_weight = 91300
[turbineenginedata]
rated_n2_rpm = 14460
static_thrust = 26300
thrustspecificfuelconsumption = 0.38
//-------------------
CFM56-7B27 (an extra 1000lbs of thrust and minimal payload increase. I would only recommend this option for short field performance or 'hot and high' operations.)
[weight_and_balance]
max_gross_weight = 174200
empty_weight = 91300
[turbineenginedata]
rated_n2_rpm = 14460
static_thrust = 27300
thrustspecificfuelconsumption = 0.38
//---------------------
All fuel requirements in nav logs should be correct now. Remember to added an hour reserve and 15 to 25 percent extra for taxi and climb.
As well as this, I plan on writing up a more advanced checklist and performance page for the aircraft to include takeoff n1 settings and the likes. Perhaps some vc/panel fixes too. I'll continue to update specs for other default aircraft. Of course these specs can be added to freeware aircraft too, as long as you check the fuel_flow_scalar is equal to 1 (I know POSKY aircraft are slightly above).
---------------------------------------
Shaun Patterson
Shaun Patterson