Thrust efficient turbofan engine

A turbofan engine comprising:

• a gas generator section for generating a gas stream flow with higher energy per unit mass flow than that contained in ambient air;
• a power turbine converting the gas stream flow into shaft power, the power turbine rotating at a first rotational speed;
• a speed reduction device driven by the power turbine;
• and
• a propulsor section including a fan driven by the power turbine through the speed reduction device at a second speed lower than the first speed for generating propulsive thrust as a mass flow rate of air through a bypass flow path, wherein the fan includes a fan tip diameter greater than about fifty (50) inches and an Engine Unit Thrust Parameter (“EUTP”) defined as net engine thrust divided by a product of the mass flow rate of air through the bypass flow path, a tip diameter of the fan and the first rotational speed of the power turbine is less than about 0.15 at one of a climb condition and a cruise condition.

A turbofan engine comprising:

• a gas generator section for generating a high energy gas stream, the gas generating section including a compressor section, combustor section and a first turbine;
• a second turbine converting the high energy gas stream flow into shaft power, the second turbine rotating at a first speed and including less than or equal to about six (6) stages;
• a geared architecture driven by the second turbine;
• and
• a propulsor section driven by the second turbine through the geared architecture at a second speed lower than the first speed, the propulsor section including a fan with a pressure ratio across the fan section less than about 1.45, the propulsor section generating propulsive thrust as a mass flow rate of air through a bypass flow path from the shaft power, wherein the fan includes a tip diameter greater than about fifty (50) inches and an Engine Unit Thrust Parameter (“EUTP”) defined as net engine thrust divided by a product of a mass flow rate of air through the bypass flow path, a tip diameter of the fan and the first rotational speed of the second turbine is less than about 0.30 at a take-off condition.