The Swearingen Merlin is a twin turboprop aircraft produced by the Swearingen Aircraft Company (later Fairchild Aircraft). It first flew in 1989 and entered service in 2000. The Merlin is known for its speed and performance capabilities as a high-end business turboprop. So how fast can the Merlin really fly? Let’s take a closer look at its top speed and performance specifications.
Key Specs
The Swearingen Merlin has the following key specifications related to speed and performance:
Maximum cruise speed | 340 knots |
Long range cruise speed | 300 knots |
Never exceed speed | 0.78 Mach |
Rate of climb | 3,000 feet per minute |
Service ceiling | 30,000 feet |
These performance metrics make the Merlin one of the fastest civilian turboprop aircraft flying today. Its high-speed cruise and rapid rate of climb allow it to fly comparable to some corporate jets.
Cruise Speed
The Merlin’s maximum cruise speed is an exceptional 340 knots, which equates to about 391 mph or 629 km/h. This speed is achieved at optimum altitude using maximum continuous power settings. 340 knots is incredibly fast for a turboprop aircraft and enables the Merlin to rival the cruise speeds of many entry-level jets.
For comparison, other fast turboprop aircraft include:
- Beechcraft King Air 350: 312 knots max cruise
- Pilatus PC-12: 260 knots max cruise
- Cessna Caravan: 186 knots max cruise
The Merlin outpaces all of these aircraft rather handily when it comes to outright speed. Only a select few turboprop models like the Piaggio Avanti come close to matching its performance.
In its long-range cruise configuration, the Merlin is still capable of sustaining 300 knots. This allows it to retain excellent speed over long distance flights. 300 knots equates to about 345 mph – still extremely fast for a propeller driven aircraft.
Never Exceed Speed
The Merlin’s never exceed speed is 0.78 Mach. This is the maximum operating limit, above which structural damage or control issues could occur. At altitude, 0.78 Mach equates to approximately 471 mph or 758 km/h. This represents the absolute top end of the Merlin’s flight envelope.
Flying at such high speeds does generate more stress on the airframe and also increases fuel burn. As a result, the Merlin typically cruises below this limit for optimal efficiency and comfort. But it highlights the performance built into the aircraft that it can safely manage speeds nearing 500 mph.
Rate of Climb
In addition to straight line speed, the Merlin also excels when it comes to its rate of climb. It is able to ascend at 3,000 feet per minute, which allows it to reach cruising altitude swiftly after takeoff.
3,000 feet per minute corresponds to about 30 meters per second. This is a very strong climb gradient for a turboprop aircraft.
For comparison, other aircraft climb rates include:
Cessna Citation M2 jet | 3,350 ft/min |
Beechcraft King Air 350 | 2,900 ft/min |
Pilatus PC-12 turboprop | 1,945 ft/min |
The Merlin essentially matches the initial climb performance of a light jet like the Citation M2. And it ascends over 50% faster than the PC-12. This rapid climb capability allows it to operate effectively at higher altitude airports and in busy airspace.
Service Ceiling
The Merlin has a certified service ceiling of 30,000 feet. This means it can theoretically fly at altitudes up to 30,000 feet, though typical cruise altitudes would be lower for optimal fuel burn and speed.
The aircraft is pressurized to allow a comfortable cabin environment at those altitudes. Its service ceiling gives it the capability to fly above most weather and congested airspace. This contributes to its reputation for smooth, efficient journeys.
Factors That Influence Speed
The Merlin’s cruise speed, climb rate, and overall performance depend on several factors:
Powerplant
The Merlin is powered by two Pratt & Whitney Canada PT6A-66 turboprop engines, each producing 1,300 horsepower. This gives it tremendous power relative to its size and underpins its speed capabilities. More power means higher airspeeds can be obtained.
Sleek Airframe
The Merlin features a low drag airframe optimized for high-speed flight. It has a slender, aerodynamic fuselage and high-aspect ratio wing designed to minimize drag at cruise speeds. Less drag equals higher possible speeds.
Weight
As with any aircraft, the Merlin’s weight impacts its performance. At lighter weights with less fuel, passengers, and cargo it can achieve faster climbs and cruising speeds. Operating near its maximum ramp weight of 12,500 pounds reduces performance slightly.
Altitude
Flying at higher altitudes where the air is thinner allows the Merlin to fly faster before the onset of compressibility drag. Optimal cruise is obtained between 25,000 to 30,000 feet. Flying lower sacrifices some speed.
Winds
Headwinds always decrease groundspeed, while tailwinds boost it. However, the Merlin’s true airspeed remains consistent. Strong headwinds may prevent it from attaining max cruise speeds.
Temperature
High temperatures reduce engine power output and aircraft lift. Flying on very hot days degrades climb performance and necessitates slower cruising speeds. Cool, dense air provides better performance.
Specialized Design
The Merlin achieves its remarkable speed through specialized design elements focused on high performance:
Engines
Its twin Pratt & Whitney Canada PT6A-66 turboprop engines provide tremendous power and acceleration for the aircraft. They deliver 1,300 horsepower each at takeoff and 1,000 horsepower during cruise. The engines utilize four compressor and turbine stages for maximum efficiency at altitude.
Wing Design
The Merlin utilizes a supercritical wing profile designed specifically for high subsonic cruise speeds. It has a flattened top surface and greater thickness and camber towards the wing root. This delays the onset of shock waves and drag rise at higher speeds.
Lightweight Materials
Advanced lightweight materials like composite honeycomb sandwich panels and titanium are used in the Merlin’s construction. This helps minimize aircraft empty weight which further improves climb and acceleration.
Sleek Shaping
Components like the nose, tail, wing fairings, and retractable landing gear are streamlined to present minimum drag to the air. Without external drag-inducing appendages, the airframe itself is highly efficient at high speed.
Advanced Avionics
Sophisticated avionics like the Rockwell Collins Pro Line 21 flight deck provide integrated automation to optimize flight characteristics. Critical for managing the aircraft at cruising speeds near 400 mph.
Speed Performance in Flight
So how does all this technology actually translate into real world speed performance when the Merlin is flying a typical mission? Here are some examples:
Takeoff Roll
At its maximum takeoff weight, the Merlin requires a runway distance of just 3,660 feet to takeoff at sea level. It is off the ground in roughly 20 seconds from brake release. Very short distances required thanks to the high power-to-weight ratio.
Initial Climb
Once airborne, the Merlin can climb at over 2,500 feet per minute even at its heaviest. It reaches 10,000 feet in under 4 minutes. Rapid initial climb allows it to efficiently transition to cruising altitudes.
Time to Altitude
The Merlin can reach a typical cruising altitude of 28,000 feet in just 14 minutes from takeoff. It will be cruising at 300 knots within about 20 minutes after becoming airborne. Very fast pressurization and climb capability.
Maximum Cruise
At 28,000 feet and lighter weights, the Merlin achieves speeds of 340 knots while burning just 990 pounds of fuel per hour. This demonstrates the excellent cruising efficiency unlocked by its advanced aerodynamics.
Landing Roll
On landing, the Merlin needs just 2,500 feet of runway to slow down and taxi off the runway at its heaviest landing weight. Powerful brakes and aerodynamic drag help it decelerate rapidly after touching down.
Mission Profile
For a hypothetical 300 nautical mile trip with VFR reserves, the Merlin can complete the entire flight in just 45 minutes. This includes a 6 minute takeoff phase, 14 minute climb, 20 minute cruise, and 5 minute descent/landing. Flying time is less than an hour door-to-door at its brisk 300 knot cruising speed. Truly a high performance aircraft.
Operational Usage
The Merlin’s speed capabilities make it ideally suited for a number of demanding operational roles:
Business Travel
Executives prize the Merlin for efficient business travel. It provides jet-like speeds with lower operating costs. Flight times are cut dramatically compared to slower turboprops. Direct flights are possible in many cases rather than connecting.
Air Ambulance
The Merlin serves as an excellent air ambulance platform. Rapid climb and cruise speeds allow it to transport patients quickly over substantial distances – saving critical time. Cabin space accommodates 2 stretchers plus medical attendants.
Charter Transport
Charter companies utilize the Merlin for on-demand passenger and cargo flights. Passengers reach destinations quicker with fewer enroute stops. Valuable cargo can also be expedited faster than using slower aircraft.
Aerial Surveying
For specialized missions like aerial photography/surveying, the Merlin’s speed maximizes coverage area for higher efficiency. It can survey more linear distance per flight hour.
Point-to-Point Shuttles
The Merlin’s performance makes it useful for point-to-point scheduled passenger shuttles between outlying communities. Fast flights raise utilization and cut operating costs for the service.
Comparison to Jet Aircraft
The Merlin’s speed capabilities place it in an elite tier of high-performance turboprop aircraft that surpass many jets. Here is how the Merlin compares to some entry-level business jets:
Aircraft | Max Cruise Speed | Max Range |
Merlin | 340 knots | 1,500 nm |
Citation Mustang | 340 knots | 1,150 nm |
Citation CJ1+ | 405 knots | 1,500 nm |
Hawker 400XP | 450 knots | 1,800 nm |
While most jets ultimately outpace it, the Merlin holds its own against the bottom tier of jet aircraft. It matches the cruise speed of the popular Citation Mustang while exceeding the range. The Merlin provides nearly 90% of the cruise speed of more advanced jets like the CJ1+ and Hawker 400XP.
And it does so while retaining the superior runway performance, fuel efficiency, and load carrying capabilities inherent in a turboprop. For many operators, the Merlin offers an unbeatable mix of speed, economy, and utility.
Conclusion
With a maximum cruise speed of 340 knots, impressive climb performance, and sophisticated aerodynamics, the Swearingen Merlin lives up to its reputation as one of the fastest civilian turboprops in operation today. It provides true jet-rivaling speed and a first-class passenger experience at lower purchase cost and operating expense than an equivalent jet aircraft. The Merlin’s speed empowers it to fulfill demanding roles ranging from corporate travel to air ambulance duties worldwide. This high-performance aircraft exemplifies how turboprop technology can rival pure jets.