Jet Engine Thrust & Compression Ratio Calculator
Calculate net jet thrust (kN / lbf), propulsive efficiency, and compressor pressure ratio.
Last reviewed by the myCalculator Editorial Team
Input Parameters
Calculation Results
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Formula & How Jet Engine Thrust & Compression Ratio Calculator Works
A jet engine produces thrust by accelerating a mass of air rearward, so net thrust is F = ṁ × (V_exhaust − V_flight). An engine passing 20 kg/s of air with an exhaust velocity of 550 m/s at a flight speed of 240 m/s produces 20 × (550 − 240) = 6,200 N. Propulsive efficiency is 2 × V₀ ÷ (V_e + V₀), which here is 480 ÷ 790 = about 61%: efficiency is highest when the exhaust speed is close to the flight speed, which is why high-bypass turbofans, with their large slow airflow, are efficient. Thrust falls with altitude as air density drops. The calculator gives an idealised figure for study and not engine certification data.
- Enter Air Mass Flow Rate (kg/s): Input your target parameter value.
- Enter Exhaust Jet Velocity (m/s): Input your target parameter value.
- Enter Aircraft Flight Speed (m/s): Input your target parameter value.
- Enter Compressor Pressure Ratio: Input your target parameter value.
- Apply Formula: Calculate using
Net Thrust F = ṁ × (V_exhaust - V_flight) | ηp = 2V₀ / (V_e + V₀). - Review Results: View exact computed answers, metrics, and worked mathematical proofs.
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Frequently Asked Questions (FAQs)
How is jet thrust calculated?
Net Thrust F = Air Mass Flow (kg/s) × (Exhaust Jet Velocity - Flight Velocity) in Newtons.
What is a good compressor pressure ratio?
Modern high-bypass turbofans (like the GE90, Trent, or CFM LEAP) operate with overall pressure ratios of 30:1 to 50:1.
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Authoritative Standards & Verified Reference Citations
Calculations and mathematical logic on this page are grounded in published statutory rules, regulatory standards, and official government data published by the following bodies:
CASR Part 91 general operating and flight rules, Part 121 fuel reserves, and flight crew licensing standards.
Aviation weather services, standard atmosphere (ISA) profiles, METAR/TAF aerodrome weather reports.
Aeronautical Information Publication (AIP), En Route Supplement Australia (ERSA), and airspace procedures.
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