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As jet fuel can be easier to obtain than avgas in remote areas, turboprop-powered aircraft like the Cessna Caravan and Quest Kodiak are used as bush airplanes. Turboprop engines are generally used on small subsonic aircraft, but the Tupolev Tu-114 can reach 470 kn (870 km/h; 540 mph).
Turboprops have an optimum speed below 460 miles per hour (740 km/h). [15] This is less than jets used by major airlines today, however propeller planes are much more efficient. [16] [need quotation to verify] The Bombardier Dash 8 Q400 turboprop is used for this reason as a regional airliner. [17] [18] [verification needed]
For instance, in aircraft, turbine (jet and turboprop) engines are typically much smaller and lighter than equivalently powerful piston engine designs, both properties reducing the levels of drag on the plane and reducing the amount of power needed to move the aircraft. Therefore, turbines are more efficient for aircraft propulsion than might ...
By this estimate, fuel efficiency is 70% better than comparable jet aircraft, although this greater efficiency is achieved only at a relatively slow 315 KTAS and FL410. [43] P.180 Avanti II Specifications now show slightly lower numbers for specific range of 3.1 km/kg (0.76 nmi/lb).
The hot-jet exhaust is an important minority of thrust, and maximum thrust is obtained by matching the two thrust contributions. [8] Turboprops generally have better performance than turbojets or turbofans at low speeds where propeller efficiency is high, but become increasingly noisy and inefficient at high speeds. [9]
Turboprop aircraft have lower fuel consumption and can operate from shorter runways than regional jets, but have higher engine maintenance costs, shorter ranges, and slower cruising speeds. [40] When world oil prices drove up short-haul airfares in 2006, an increasing number of airlines that had bought regional jets began to reassess turboprop ...
A corollary of this is that, particularly in air breathing engines, it is more energy efficient to accelerate a large amount of air by a small amount, than it is to accelerate a small amount of air by a large amount, even though the thrust is the same. This is why turbofan engines are more efficient than simple jet engines at subsonic speeds.
Aircraft engine performance refers to factors including thrust or shaft power for fuel consumed, weight, cost, outside dimensions and life. It includes meeting regulated environmental limits which apply to emissions of noise and chemical pollutants, and regulated safety aspects which require a design that can safely tolerate environmental hazards such as birds, rain, hail and icing conditions.