Definition
A combined power rating used for turboprop engines that adds the shaft horsepower delivered to the propeller and the small additional thrust produced by the engine's exhaust gases, expressed as a single horsepower figure. It represents the total useful power the engine produces, not just the power turning the propeller.
Plain English
It is the total power a turboprop engine produces, counting both the power that spins the propeller and the small extra push from the jet exhaust, added together and shown as one horsepower number.
Context Anchor
Seen in turboprop engine and performance discussions when comparing total engine output, not just the power delivered to the propeller.
Derivation
Equivalent means treated as the same for measurement purposes. Shaft horsepower is the power measured at the engine's output shaft. Together the term means: 'expressed as if it were all coming through the shaft, even though some of it is jet thrust.' The word equivalent is the key — it tells you two different things (shaft power and exhaust thrust) are being combined into one comparable number.
Why Pilots Care
Turboprop engines produce useful thrust from their exhaust on top of the power turning the propeller. Looking only at shaft horsepower understates what the engine is actually delivering. Equivalent shaft horsepower gives a truer picture of total engine output and is the figure commonly used to compare turboprop engines.
Grounding Statement
In a turboprop, most of the engine’s useful power turns the propeller, but some useful push can still come from exhaust leaving the engine.
Intuition Check
Equivalent does not mean approximate or less real here. It means the exhaust push has been converted into the same unit as shaft horsepower so the two can be added.
Example Sentence 1
The engine is rated at 1,100 equivalent shaft horsepower, which includes both the power going to the propeller and the thrust from the exhaust.
Example Sentence 2
When comparing two turboprops, the one with higher equivalent shaft horsepower showed better climb performance in the handbook tables.