Two-stroke vs. four-stroke: Do two-stroke cycle engines generally require a lighter flywheel due to more uniform torque delivery?

Introduction / Context:
Flywheel sizing depends on torque fluctuation within a cycle. Two-stroke engines deliver a power event every revolution, while four-stroke engines deliver power every second revolution. This directly affects the angular speed variation and the inertia needed to smooth it.

Given Data / Assumptions:

• Two-stroke: one power stroke per crank revolution.
• Four-stroke: one power stroke per two revolutions.
• Other variables (number of cylinders, firing order) being comparable.

Concept / Approach:
More frequent power strokes reduce the interval between torque inputs, decreasing cyclic speed ripple. Hence, the required energy storage in the flywheel to keep speed within limits is lower in a two-stroke for the same cylinder and mean torque, implying a lighter flywheel suffices. Multi-cylinder four-strokes mitigate this with overlapping firing orders but the single-cylinder comparison reveals the principle clearly.

Step-by-Step Solution:

Verification / Alternative check:
Classic motorcycle and small two-stroke engines exhibit small/light flywheels relative to similar displacement single-cylinder four-strokes, supporting the concept empirically.

Why Other Options Are Wrong:

• Disagree: Ignores fundamental power-event frequency difference.
• Conditional answers: While application specifics matter, the baseline engineering rationale remains valid.

Common Pitfalls:
Overlooking the effect of cylinder count; a multi-cylinder four-stroke can have smooth torque and smaller flywheel per cylinder, but the question refers to the inherent cycle property.

Final Answer:
Agree