Reason 5 – Turbocharged Cirrus

In a 500 nautical mile flight, how does the Piper Archer compare with the Cirrus SR22TN turbo-normalized aircraft? Is the Archer’s smaller 180 HP Lycoming engine more efficient than the SR22TN’s larger 310 HP Continental engine? Which plane consumes more fuel on the trip?

For years, I flew the Piper Archer II between Houston Texas and Birmingham Alabama and believed the smaller engine was more efficient but I was mistaken.

Reason 5 – Good NMPG Performance Cross-Country

The Cirrus SR22TN Tornado Alley Turbo-normalized engine delivers more Nautical Miles Per Gallon performance (NMPG) than the Piper Archer.

NMPG Performance (500 Nautical Miles)

Aircraft NMPG GPH Gallons TAS Hours
SR22TN 10.3 16.1 48 193 2.9
Piper Archer II  9.7 10.5 52 115 5.0

Note: Example assumes no headwind or tailwind for either aircraft. The SR22TN is at 75% cruise power and 16,000 ft. The Archer is at best cruise power and 8,000 ft.

The Piper Archer must have a fuel stop which necessitates a second en route climb back to cruise. The Archer spends more than 36 minutes with two en route climbs and consumes a greater amount of fuel in the process (see Reason 4 – Turbocharged Cirrus: Time in Climb Performance).

You’re probably not surprised that the Cirrus Turbo beats the Piper Archer by a wide margin on flight time, even in this example at 75% power and no tailwinds.  But what does surprise me is that the Cirrus Turbo can fly 500 nautical miles on about the same or less fuel as the Piper Archer.

When I was looking at pre-owned Cirrus aircraft, my natural inclination was toward normally aspirated models, because aviation articles and marketing brochure write-ups touted turbocharging for fast airspeeds, but left an impression they’re thirsty inefficient gas hogs.

Some turbocharged engines on the market are inefficient. And, many older legacy turbocharged engines were not designed very well. General Aviation needs companies that innovate and promote better piston engine performance, because pilots want it all – speed, efficiency, comfort and safety.

Turbocharged planes have an edge with winds aloft that is not discussed in this example. More often, the turbocharged Cirrus takes advantage of winds aloft because a wider range of altitude choices are quickly available. Net result is better ground speeds.  It’s a benefit normally aspirated engines cannot easily match.

Appendix

Piper Archer II, Example 500 Nautical Mile Trip

Piper Archer II Taxi Climb Cruise Total
Time 24.0 36.2 236.9 5.0
Gallons 1.2 9.1 41.5 51.7
NM 46 454 500

Note: Trip requires a fuel stop, three ground taxis, two climbs 8,000 ft. Example assumes no headwind or tailwind.

Cirrus SR22TN, Example 500 Nautical Mile Trip

SR22TN Taxi Climb Cruise Total
Time 12.5 13.33 147.2 2.9
Gallons 0.8 8.0 39.5 48.3
NM 27 473 500

Note: Trip is non-stop, two ground taxis, one climb to 16,000 ft. and 75% cruise power, TAS 193. Example assumes no headwind or tailwind.

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