By Rafael Payão, director of Clear Prop Aeronaves.
One of the biggest controversies in the market nowadays and reason for debates, criticisms and even fights! What is the best plane to buy? Meridian/M500 or JetProp?
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Anyway… Despite looking like the same planes, the Piper JetProp and Meridian have differences that define markets with different needs.
However, the purpose of this article is to present the main differences, pointing out the advantages of each of the options.
But first, let's briefly describe each one of them.
JETPROP
The JetProp project appeared in 1998, in the DLX version, equipped with a PT6A-34 engine of 750 shp, but “prorated” to 560 shp.
The fuselage is the same as the Piper Malibu Mirage, however, some systems have been changed, favoring the operation of the new engine.
Among the changes listed above, highlight the fuel tanks. A frontal fuel tank was added, between the engine and the nose bag, which is fed by the wing tanks – only – eliminating the restriction of operation in extremely negative temperatures, since all the fuel that goes to the engine es through this tank front. In the wings, cells were added at the tips. However, fuel capacity has increased from 120 gallons to 151 gallons.
The electrical system has also undergone changes, with the addition of a second battery that can be used in conjunction with the first, to drive the engine, thus avoiding premature battery depletion.
The JetProp can be equipped with three engine versions: the PT6A-34, -35 and -21, which have less thermodynamic power and 10 shp less than rated power.
The difference between “-34” and “-35” is the type of compressors used. In the first version, the engine seems to have been designed to operate at lower altitudes, especially in non-pressurized aircraft, while in the latter, it is equipped with compressors that have a more aggressive design carried over from the “-135A” that equipped the C90GT onwards. . The interval between overhauls is also different: the “-34” has 4.000 hours and the “-35”, 3.600 hours.
The -21 engine is installed in the DL versions of the JetProp, created years after the first one, DLX. The objective is to make the project cheaper, despite the reduced performance compared to DLX.
MERIDIAN
The Meridian received certification in 2000 by the FAA, but in Brazil it has been accepted since 2009. Note that the plane came on the market after the JetProp DLX.
The project was born from the Piper Malibu, which served as a platform for its development. However, the main changes are concentrated in the wings – with a larger span -, the empennage – with a larger area of stabilizers – and various systems, such as fuel, landing gear, etc.
It is important to note that the larger empennage area and wings favor a safer and smoother stall behavior, also due to the installation of a longer engine on that old fuselage.
The engine installed is the same used in the King Air B200 – the PT6A-42A – with the difference that it has a manual power override control, in case of failure in the FCU, hence the letter “A” after the engine designation.
Even with a maximum thermodynamic power of 850 shp, Piper engineers consider it inappropriate to provide useful power greater than 500 shp (despite the 560 shp in the JetProp), as it would harm the aircraft's longitudinal stability. However, the advantage of having a thermodynamic power well above that available allows operations with a cold engine, mainly applied to the reality of the Meridian/M500 that operates integrally with the inertial system[1] enabled (in JetProp, there is an option to enable or disable).
Due to the extra “breath” of the engine, as well as dual window panes, it is possible to fly at higher altitudes than the JetProp (FL300 versus the JetProp's FL270).
Finally, the Meridian was conceived to be operated by a pilot/owner, with the least possible complexity of operation. With that, it is noted the installation of only one lever that controls power and rotation (automatic governor), inertial activated integrally and automatic tank exchange.
[1] Inertial system in the engine allows separation of debris, ice, dirt and other solid particles from entering the engine. The downside is the “hijacking” of available power.
COMPARATIVE
Before proceeding with the comparison, read the preliminary conclusions that Clear Prop defined:
Statement 1: The life limit of a JetProp is less than a Meridian.
As the JetProp is a Malibu (later Malibu Mirage) with another type of engine installed, therefore, it considers the respective airframe limit: 10.145 hours as the fuselage life limit and 15.580 hours as the wing life limit. However, the values cannot be applied equally after the conversion, as Piper claims that the large change can lead to accelerated stress and fatigue in the cell. However, the following formula applies to define the lifetime limit of a JetProp after conversion:
Fuselage life = 10.145 – [(10145 – total hours before conversion) * 10%]
Wing health = 15.580 – [(15580 – total hours before conversion) *15%]
Therefore, we conclude that the best JetProp to buy is one that was converted early in its life. That is, the greater the accumulated total before the conversion, the worse the candidate, regardless of the total hours announced at the time of the sale.
As for the Meridian, the fuselage life limit is 10.145 hours and 10.225 hours for the wings (13.349 hours for older models, with lower maximum takeoff weight).
Statement 2: The JetProp is lighter than the Meridian.
The maximum takeoff weight of a JetProp is close to 2.000 kg, while that of the Meridian totals 2.310 kg. In this way, the amount charged at airports increases, as the Meridian enters the higher weight range.
As the Meridian engine has greater thermodynamic power, naturally its engine is heavier. Furthermore, it is fixed on a magnesium cradle, heavier than the aluminum one, installed on the JetProps.
The weight difference is also related to the JetProp's smaller wing, smaller empennage area and smaller fuel tank.
Statement 3: The JetProp has increased fuel efficiency.
That is, the two planes fly at the same speed at equal levels, however, the Meridian spends 143 to 152 liters of kerosene per hour, and the JetProp 117 to 124 liters of kerosene per hour.
The Meridian can even fly 10kt faster, if it goes beyond FL270, which is the JetProp ceiling, but consumption is still high.
What justifies the better efficiency of JetProp:
– Air intake for the engine that makes the effective power rise, naturally;
– Due to the 60 shp more power available and less weight, the plane can develop a higher rate of climb, leveling faster;
– Having a smaller wing span and smaller empennage area, there is less induced drag;
– The Meridian Engine operates with an inertial system fully activated, making consumption naturally high. In JetProp, the pilot has control over the activation of this system.
Statement 4: JetProp tends to have higher "Range".
Even having a smaller tank than the Meridian, the JetProp can fly for greater distances, due to all the reasons listed in statement number 3.
Statement 5: JetProp maneuver speed is higher.
The maneuvering speed is calculated for greater command deflections. Therefore, in moderate to severe turbulence, the JetProp has a higher recommended speed than the Meridian (137 kt against 127 kt for the Meridian).
Statement 6: Easy and safer operation on the Meridian/M500.
As discussed at the beginning, the Meridian was designed for pilots who are also owners, so the focus was on the least possible complexity of operation. As a result, some facilities were adopted, such as a single lever to control power and propeller rotation, and a fully active inertial system.
Statement 7: Meridian's maximum operating speed is higher.
In cases of a faster descent, for example, the Meridian can develop greater speed, contributing positively to the flow of air traffic.
The Meridian's VMO is 188kt, against 172kt for the JetProp.
Statement 8: Flights with lower speed, more suitable for Meridian/M500.
By having a larger wingspan and a larger empennage area, the Meridian and M500 have greater maneuverability, while flying at low height and lower speed.
However, this does not mean that the Meridian uses a shorter runway for takeoffs and landings. In contrast, JetProp continues to use the shortest runway length.
Statement 9: the Meridian/M500 has a higher operating ceiling.
Due to the improved pressurization system and also the engine with more power left over, the Meridian/M500 has an operational ceiling of 30.000 feet (FL300), while the JetProp is at a maximum of 27.000 feet (FL270).
Statement 10: considering "full tank”, the Meridian has a higher carrying capacity.
With full tanks, the Meridian/M500 can carry up to 3 adults and still stay inside the envelope, while in the JetProp the ratio drops to up to 2 occupants.
Statement 11: JetProp's depreciation is less than Meridian's.
This is because JetProp has depreciated as much as possible early in its life after converting.
Statement 12: Meridian/M500 resale liquidity is higher.
Because it is a plane manufactured by Piper itself, the number of deliveries in the world of Meridian and M500 still exceeds that of JetProp.
Statement 13: there is no longer the possibility of a Mirage 2022, converted to JetProp.
Perhaps, fearing losing the market for the M500, Piper stopped production of the Mirage.
Statement 14: JetProp uses shorter runway length for operation.
Ultimately, we will never claim that one plane is better than another, but rather that one is best suited to an operator's unique needs. However, considering that the buyer's priorities are: lower operating costs, lower purchase price, mostly business flights, long flights and extra “space” for luggage, the JetProp is the most suitable aircraft; however, if the priorities are: higher resale liquidity, age (since Piper never manufactured the Mirage again), simplicity of operation (also understand, lower operational risk) and greater availability of payload, the Meridian/M500 is the most appropriate.
Finally, I would like to point out that the Clear Prop team and I are available for any questions and keep an eye on the market to always provide complete and accurate information to our customers. And, soon, we will publish our great news: a software that calculates annual budgets for the aircraft that the chooses. Follow our social media to learn more.
Good flights and great deals!
