Reading Cessna 150 and 152 Performance Figures: Comparable Conditions
Two Cessna 150/152 performance numbers are comparable only when they describe sufficiently similar conditions and the same kind of quantity. A cruise figure, maximum-range figure and runway distance can each be accurate in its own source while producing a misleading comparison when their qualifiers are removed. The first research task is to establish what each number actually measures.
Begin with the metric and units
Ground roll and distance over a 50-foot obstacle are different quantities. Comparing one aircraft's ground roll with another's obstacle distance does not establish a runway-performance advantage. The takeoff-distance guide and landing-distance guide retain those labels separately.
Speed units also need to remain attached to the original values. A conversion can change the unit, but it cannot supply a missing speed definition, power setting or altitude. Preserve the source figure and its labels before attempting a normalized comparison so that another reader can trace the calculation.
Cruise requires power and altitude context
The cruise-speed reference retains power and altitude where available. A higher published speed at a different power setting is not, by itself, evidence that one aircraft is more efficient. Fuel consumption and the applicable configuration would also be needed to answer an efficiency question.
Where a source omits a condition, show the omission. Do not fill it with a familiar handbook setting from another model or year. A blank field limits the conclusion that can be drawn; it is not permission to assume standard conditions silently.
Range is not endurance or usable fuel alone
The range guide distinguishes fuel arrangements and reserve bases in the retained records. A larger fuel capacity does not translate directly into a proportional range increase without a compatible consumption and operating basis. Similarly, dividing a published range by an unrelated cruise speed does not produce an authoritative endurance figure.
No independent, complete condition-specific fuel-flow series is established by the current evidence. That is why a standalone numerical fuel-burn or endurance comparison remains deferred. The existing range and ownership fuel-cost pages can explain the relationships without inventing the missing inputs.
Preserve configuration and source identity
Model year, engine, propeller, fuel configuration and aircraft category can all be relevant to a performance claim. A Reims aircraft should not receive U.S. model figures merely because its dimensions or engine appear similar. A converted aircraft also needs its own applicable performance evidence rather than a simple horsepower adjustment to a factory table.
A useful comparison ends with a qualified statement: which source records were compared, which conditions match, and which differences remain unresolved. It may legitimately conclude that the available numbers do not support a ranking. This is research interpretation, not a replacement for the applicable aircraft performance charts or a flight-planning calculation.
Resolve two common ambiguities before comparing rows
Airspeed type and atmospheric input often hide behind an apparently simple number. The IAS, CAS, TAS and groundspeed guide explains why a unit conversion cannot remove position error, density effects or wind. Record both the speed basis and the unit when copying a published figure; otherwise a carefully converted number can still answer the wrong question.
The density-altitude guide separates airport elevation, pressure altitude and the temperature-related density question. Use the inputs requested by the applicable chart. A chart asking for pressure altitude and temperature does not automatically accept density altitude as a replacement axis, and a headline sea-level figure cannot establish capability on a hot departure from a higher airport.