For pilots who use small aircraft in their fleet, the choice between radial and turbine engines can often be a question of cost, but there are other factors that should also be considered in regard to which engine can be more applicable for certain functions. This includes the maintenance and repairs that may be required for upkeep, but can also include the capacity and power that is required for the aircraft.
Both radial and turbine engines still use internal combustion as their energy source, but the differences in design do result in a variance of output. A further difference that is evidenced in the engines is changes to the initial design, which can translate to increased fuel efficiency and better horsepower. Radial engines, such as the R-1340, did not see significant alterations from the time it was first introduced in 1925 until Pratt stopped production in 1960. While this is impressive in regard to the innovation of this original design, it also means that performance in radial engines is fairly consistent.
One of the biggest benefits of a radial engine is its effectiveness for sudden changes in speed, which makes it highly practical for the agricultural industry. This is a result of the unique blower design, which not only anchors the engine, but also protects internal parts in instances where there is a sudden acceleration or deceleration. The effect is promoted through the manner in which fuel and air is delivered to the cylinders, as well as the construction of the crankshaft.
Radial engines produce significant power, but can be heavier than turbines. The PT6 engine introduced an impeller that diffused the heat of the combustion and also provided greater power with less weight. The turbine design is more complex than the radial in regards to mechanical operation, but it is often preferred for less vibration, better fuel efficiency, and less overall maintenance. This means that smaller turbines can still produce the power of a larger radial, with far less weight involved.
A further aspect of turbine engines is the fact that the PT6 has been refined since its first installation. Although the mechanical changes to the engine design have still retained the initial model, these alterations have resulted in better cooling, greater thrust, and better control with speed changes.
Both radial and turbine engines have their benefits in terms of practical application. Choices between these engines do sometimes come down to preference, but owners and managers will also want to consider the use of the aircraft and the cost of engine maintenance when making a decision. While the historical performance of both radial and turbine engines can be a guiding point, it can also be important to look at the changes to each design, in order to objectively compare performance.