Cessna 337 Guide and Specs

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Since its introduction in 1965, the Cessna 337 Skymaster, a general aviation classic with a unique multi-engine design, has served its owners. The Cessna Model 337 was originally nicknamed the Super Skymaster since it was an enhanced version of the Model 336.

Still, Cessna eventually omitted the “Super” from the name and renamed it the 337 Skymaster as well. This engine arrangement existed before to Cessna, and you can view a Dornier Do 335 with its rear engine behind the tail at the National Air and Space Museum.

The aircraft’s propulsion system is a push-pull layout, with one engine in the front as a tractor and another in the back as a pusher. The engines were designed to create a multi-engine aircraft that is easier to manage than typical multi-engine aircraft with engines on their wings.

Because the engines on the Cessna 337 are positioned in such a way, there is no yaw moment caused by the remaining engine in the event of a single-engine failure. This was a great idea at the time Skymaster was built because there were more accidents during the multi-engine rating at the time.

Today, the Cessna 337 Skymaster continues to draw the attention of aviators due to its distinctive engine design and the sound it produces. Such attention that the famous Flying Bulls also use Skymasters.

However, keep in mind that this one-of-a-kind arrangement has some drawbacks, including rear engine shut down during takeoff, which is especially problematic on hot days. Even if it is a stunning and one-of-a-kind aircraft, maintenance and costs might be a major issue for you.

Aircraft Design

Cessna 337 Skymaster

The Cessna 337 Skymaster is an excellent chance to discuss how airplanes were developed in the first place because there is a rationale behind all the combinations and options. I wanted to use this chance to introduce the basics of design. However, you may scroll down to the specifications if you like.

The engineers in charge of early design will endeavor to manage the case to construct to generate a successful airplane as a result of a satisfying solution to many disparate challenges. In an ideal world, our airplane would have a low empty weight, high performance, simple handling, a strong light structure, and be economical to produce and run.

All of these pose unique challenges to the design process, as well as each purchase and operational cost while enhancing the performance of earlier technologies.

The plane’s specifications state how far, how quick, how high, how heavy, how long the takeoff and landing distances must be, and so on. Missions, on the other hand, refer to what the plane is meant to perform. Will it be a passenger transport plane or a mission-complex aircraft like those seen in military examples?

When an aircraft designer begins a design, the first step is preliminary design, which includes numerous iterations. When a new aircraft is in mind, it is essentially a dot in space with no shape other than the jobs it will do and the standards it must satisfy.

The goal here is to identify what the requisite thrust, wing specifications will be (Lift coefficient, etc.). Only once these have been discovered after several iterations can a more thorough design be created.

If you are interested, you can check constraint diagrams where the allowable design area is determined. T/W (Thrust to Weight Ratio) – W/S (Wing Loading) graphs or Stall Speed – Cruise Speed Carpet Plots are two of the examples you can check.

In a nutshell, that is the graph that engineers use in the early stages to determine the best design points based on the sustained turn, T-O run, Climb, and other needs.

So now we know that after some preliminary decisions regarding the needed lift, thrust, and weight restrictions are established, engineers will have to devise configurations that will match these criteria. One of these is, of course, the propulsion system, which will provide us with the thrust we need to overcome drag.

Should it have a single or multiple engines; should it be propelled by a propeller or a turbofan; should it be a pusher or a tractor? All of them have advantages and disadvantages when compared to one another.

Propeller-driven aircraft, for example, perform better at lower altitudes, whereas piston engines waste less fuel and perform better at lower altitudes. However, when compared to turbojet and turbofan engines, this will be a low-performance arrangement. Turboprops, on the other hand, are a hybrid of the two and work well at both low and high altitudes.

When it comes to aircraft propeller arrangement, there are two options: tractor and pusher. Most general aviation aircraft have propellers in front of them that allow the aircraft to be “dragged” through the air. The pusher arrangement, on the other hand, positions the airscrew behind the aircraft and drives it forward.

Cessna 337 Configuration and Specifications

Cessna 337 Skymaster

So, when it comes to the Cessna 337 Skymaster, what configuration are we talking about? The wing, propellers, and tail design are the most attention-getting choices I see.

The designer should consider accessibility, field-of-view, stability and control, aerodynamic drag, and other factors while deciding on the position of the vertical wing. The Cessna 337 Skymaster’s high wing design contributes to two characteristics that, as far as I can tell, owners love. One is that it provides excellent visibility and field of vision (thus its usage as an observation aircraft), and the other is that it aids to stability.

The push-pull design of the Cessna 337, on the other hand, is the true cause for its legendary status. The multi-engine aircraft has two engines, one of which is configured as a tractor and the other as a pusher. As previously stated, this design provides the benefit of centerline thrust and combines the benefits and drawbacks of both layouts.

As shown in the diagram below, there is a distance between the center of gravity and the engine on the wing in traditional multi-engine setups, which implies that in the event of a single-engine failure, the remaining engine will generate a yaw moment equal to thrust times distance Yt.

Normally, the pilot must produce an opposite yaw moment using the rudder, but in the case of a Cessna 337 Skymaster, the only difference is the loss of power in the event of a single-engine failure.

Of course, as with any advantages, there are drawbacks to this design. The rear engine tends to overheat, as noted by the aircraft’s owners, especially during the taxi. As a result, several pilots attempted takeoff without noticing the back engine had shut down.

That is a logical result since the airflow to the rear engine will be weak during the taxi, but air will flow into the engine more easily during the flight through the intake channel at the top of the aircraft.

The EGT (Exhaust Gas Temperature) indicator is recommended since it provides the clearest indication that the rear engine is not operating. Because you won’t be able to view the back engine well, it’s critical to make sure it’s working properly.

The turbulent air flowing from the front engine is another downside of this arrangement. Because the propellers in the front of the plane have already disturbed the air, the rear engine will meet with the turbulent air. This indicates two things: first, the back engine will not be as efficient as predicted due to the turbulent air, and it will produce more noise.

When it comes to the cabin, the top half of the clamshell door opens out and up, while the bottom part descends to function as an access step. The standard seating layout is four seats. However, unpressurized Skymasters may have six. These extra seats take up the aft cabin luggage compartment. Thus there will be no place for bags within the cabin if they are fitted.

Table 1: Cessna 337D Specs – Source: Jane’s All The World’s Aircraft 1969-70

Wingspan 38 ft 09 in (11.81 m) Empty Weight 2,655 lb (1,204 kg)
Height 9 ft 4 in (2.84 m) MTOW 4,400 lb (1,996 kg)
Length 29 ft 9 in (9.07 m) Fuel Capacity 92 US gal (77 imp gal; 350 L) normal, 128 US gal (107 imp gal; 480 L) with auxiliary tanks
Wing Area 201 sq ft (18.7 m2) Capacity 1+5
Aspect Ratio 7.18:1 Airfoil NACA 2412 (Root)-NACA 2409 (Tip)

Cessna 337 Performance and Handling

Cessna 337
Figure 1: Conventional Multiengine Configuration -Source: R. Nelson, Flight Stability and Automatic Control, McGraw-Hill Educaiton, 1998

The Cessna 337 has been powered by a variety of Continental IO-360 engines, each of which generates 210 horsepower, since its inception. In later models, the Continental IO-360-C engines that powered the Model 337 were replaced with turbocharged engines.

The aircraft is lightweight, according to its owners, and its power, which comes from two centerline engines, allows it to easily take off and land on small airstrips. The aircraft features a very light control system for maneuvering when compared to its size.

It may be claimed that the Cessna 337 Skymaster is a suitable choice for single-engine pilots looking to upgrade to a twin-engine aircraft. Multiengine safety is, of course, incorporated as part of the package, as is the advantage of centerline confidence. Don’t forget about the drawbacks, though.

Table 2: Cessna 337 Performance -Source:  https://www.flyingbulls.at/en/fleet/cessna-337-skymaster-push-pull

Engine Continental IO-360 CB Engine Displacement Approx. 6 L
Horsepower 2*210 HP Max Operating Altitude 30,000 ft (9,144 m)
Cruising Speed 160 kts (290 km/h) Max. Speed 190 kts (360 km/h)
Service Ceiling 19.500 ft (5,950 m) Max Endurance Approx. 5 h
Fuel Consumption Approx. 85 L Range 650 nm (1,200 km)

Cessna 337 Modifications and Upgrades

Cessna 337
Figure 2 : Cessna Skymaster – Source: Gudmundsson, S. (2014). General Aviation Aircraft Design Applied Methods And Procedures. Elsevier.

Cessna 337 Skymaster has many available mods, which can be seen from the below list. (Source: cessnaskymaster.com)

  • “25 – 50 gallons underwing tanks.
  • Air Conditioning
  • Landing gear in transit warning light for ’73-80 337s
  • 40-gallon Auxiliary Fuel tanks (tip tanks)
  • Wing Extensions for all Models (~10% increase performance)
  • Winglets (performance enhancements)
  • 620-800 hp engine conversions for all Skymasters
  • 3 bladed propellers for all Skymasters
  • STOL kit (all composite leading-edge cuff)
  • Fuel Jettison System
  • Low Oil Pressure warning system
  • Speed Brakes
  • Fire detection system for both engines”

You can also install a new avionics suite and autopilot for your Cessna 337 and upgrade its comfort.

Cessna 337 Prices

The Cessna Model 337 Skymaster had several variants during the years of manufacture, and because it is an older aircraft, most of the aircraft have also been upgraded by the owners.

Given these factors, it’s reasonable to expect a broad variety of preowned prices. Currently, prices range from $75,000 to $160,000. However, customized, enhanced Skymasters like “The Rocket II,” which sell for $430,000, are available.

The Continental TSIO-360-CB engines have been extensively rebuilt, and the avionics suite has been replaced on these modified Rocket 2 aircraft.

Cessna 337 Maintenance Schedule

Cessna 337 Skymaster

Even though the Cessna 337 Skymaster has an excellent performance with two engines, the rear engine issues are widely recognized. It earned a reputation for being a high-maintenance beast.

Because of the engines’ unusual location, entry is difficult, and it contains systems that will cause the majority of maintenance issues. You may encounter hefty maintenance expenditures, particularly in pressurized and turbo variants.

Servicing Intervals Check List

  • Each 50 Hours: Battery, Engine Oil, Oil Filters, Induction Air Filters, Nose Gear Torque Links.
  • Each 100 Hours: Fuel Strainers, Fuel Selector Valves, Brake Master Cylinders, Shimmy Dampener, Landing Gear Universal Joints, Landing Gear Down Lock, Hydraulic System Filter.
  • Each 500 Hours: Wheel Bearings, Vacuum System Central Air Filter.
  • As Required: Nose Gear Shock Strut, Hydraulic Fluid Reservoir.

Cessna 337 Common Problems

The Cessna 337 Skymaster’s worst flaw is its high maintenance costs. Because the airplane is unique and has complex systems, there may be several issues that result in lengthy and costly maintenance periods.

Engine shutdown during takeoff is one of the most well-known frequent problems, which has led to pilots attempting to take off with only one engine. Because it’s so difficult to observe and comprehend when the back engine isn’t running, you should be cautious while using the gauges. The back engine cannot cool down on hot days or during taxi rides, resulting in overheating.

Cessna 337 Where to Find Replacement Parts

Replacement parts, upgrade kits, and modifications are available from a variety of service facilities and dealers around the country. In addition, the majority of the parts are available for purchase online. Because this is an older aircraft, there are a plethora of replacement parts available on the market.

Cessna 337 Insurance Options

Cessna 337 Skymaster

There are two types of aviation insurance for the Cessna 337. The first is Liability Coverage, which comes standard with all aircraft insurance policies.

Hull Coverage, on the other hand, is an optional add-on that protects the structure of the aircraft from damage. Aviation liability insurance protects the aircraft owner or policyholder against claims for property damage and bodily injury caused by the aircraft outside the aircraft.

Because of the Cessna 337 Skymaster’s poor maintenance record and engine troubles, you may have issues with insurance providers that are wary of the aircraft. This can lead to significant expenses and frequent flight safety needs, particularly for hull covers.

Cessna 337 Resale Value

You might be able to resell the plane for $150,000 if it has been well maintained. A pre-owned Cessna 337, on the other hand, can usually be found for under $100,000.

Cessna 337 Owner Reviews

Owners like their aircraft’s individuality, and they are pleased with the aircraft’s handling and overall performance. However, some people are dissatisfied with the maintenance and insurance issues. The Cessna 337 Skymaster is a lovely airplane that will fly well and demand care indefinitely until its owners quit paying close attention to its maintenance.

Cessna 337 Similar Aircraft

Dornier Do 335

If we use the term “similar aircraft” to refer to aircraft with comparable engine configurations, we may talk about the Dornier Do 335. Aside from that, the Cessna 337 is a one-of-a-kind airplane. Nonetheless, it was compared to Piper’s Seneca II and Beech’s Baron at the time.

Cessna 337 Clubs You Can Join

There is a great Skymaster forum where you may get a lot of important information from other owners. You may access the forum by going to:

Skymaster Owners And Pilots Site (SOAP) C336, C337, O-2 (http://www.337skymaster.com).

There is also an association for Cessna owners called Cessna Flyer Association.

FAQ: Frequently Asked Questions

Question: Does Cessna Still Make the Skymaster?

Answer: No, Cessna doesn’t produce any new Skymaster. But you can find preowned models or completely upgraded aircraft like Rocket II.

Question: Can a Cessna Skymaster Fly on One Engine?

Answer: Yes, it can fly on one engine as other two-engine aircraft, and that is one of the safety features multi-engine aircraft are preferred by owners.

Question: Is the Cessna 337 Pressurized?

Answer: Cessna 337 Skymaster has pressurized and unpressurized versions.

Question: How Much Does a Cessna Skymaster Cost?

Answer: Currently, Cessna Skymaster’s price ranges from $75,000 to $160,000, but there are custom upgraded Skymasters like “The Rocket II,” which are sold for $430,000.

References:

  • Gudmundsson, S. (2014). General Aviation Aircraft Design Applied Methods And Procedures. Elsevier.
  • Cessna Skymaster – Aviation Consumer. (2019, January 1). Aviation Consumer. https://www.aviationconsumer.com/used-aircraft-guide/cessna-skymaster/.
  • The Rocket II | Specifications. (n.d.). The Rocket II | Specifications. http://www.therocket2.com/specs.htm.
  • Cessna Skymaster Mods. (n.d.). Aviation Enterprises, LLC. http://www.cessnaskymaster.com/mods.html.
  • FlyingBulls (n.d.). Cessna 337 Skymaster “Push Pull” | The Flying Bulls. Cessna 337 Skymaster “Push Pull” | The Flying Bulls. https://www.flyingbulls.at/en/fleet/cessna-337-skymaster-push-pull.
  • SKYbrary Aviation Safety (n.d.). Exhaust Gas Temperature (EGT) – SKYbrary Aviation Safety. Exhaust Gas Temperature (EGT) – SKYbrary Aviation Safety. https://www.skybrary.aero/index.php/Exhaust_Gas_Temperature_(EGT).
  • Phelps, M. (2010). Cessna Skymaster Breaks Up Over New Jersey Airport | Flying. Cessna Skymaster Breaks Up Over New Jersey Airport | Flying. https://www.flyingmag.com/safety/accident-investigations/cessna-skymaster-breaks-over-new-jersey-airport/.
  • Air Progress (1980). Air Progress 1980-02: Vol 42 Iss 2 : Free Download, Borrow, And Streaming : Internet Archive. Internet Archive. https://archive.org/details/sim_air-progress_1980-02_42_2/page/n40/mode/1up?view=theater.

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