Classic Jetliners: The McDonnell Douglas DC-10

The McDonnell Douglas DC-10, the most renowned trijet widebody aircraft in history, stands out as an intriguing commercial aircraft I’ve had the pleasure to observe. Although it carries a history marred with incidents, its popularity remains untouched. My memories hold clear images of this aircraft, adorned in the colors of Philippine Airlines. Unfortunately, the opportunity to experience a journey aboard this majestic aircraft during its service with PAL never materialized. The DC-10’s evolution led to a more advanced variant, the MD-11, a topic I will explore further in a subsequent discussion.

The McDonnell Douglas DC-10 is a standout example in the history of aviation, an American-manufactured trijet aircraft created to cater to long-haul flights. It was conceived to step into the shoes of the DC-8, boasting a twin-aisle layout and a typical seating capacity of 270, split across two classes. This powerful trijet aircraft came equipped with two turbofans on underwing pylons and a third one at the base of the vertical stabilizer.

The DC-10 project was kick-started in 1966 when American Airlines expressed their interest in a large passenger jet smaller than the Boeing 747. They intended to serve smaller airfields while maintaining the range of the larger aircraft, and this opened new opportunities in widebody passenger transport.

Design of the DC-10

The McDonnell Douglas DC-10 serves as a classic example of aviation design, showcasing the innovative spirit of its time. This wide-body, low-wing aircraft, specifically designed for medium to long-range flights, demonstrated comparable endurance to the Boeing 747 but had the additional advantage of being able to access airports with shorter runways.

What set the DC-10 apart was its ability to accommodate between 250 and 380 passengers on its main deck, with the lower level generally allocated for storage and food preparation. An essential characteristic of the DC-10 was its trijet design. It had three turbofan engines, two under the wings, and one on top of the rear fuselage. The engines not only produced less noise but also minimized smoke emission, earning the DC-10 high marks for environmental considerations.

For landing, the aircraft had thrust reversers installed to decrease the landing distance, making it a versatile option for various airports. To top it all off, the DC-10 was designed to operate under any weather conditions, truly marking its utility and reliability in the aviation industry.

Innovation in Flight Controls and Hydraulic Systems

The McDonnell Douglas DC-10 featured both primary and secondary flight controls, including inboard and outboard ailerons, two-section elevators, and a two-section rudder. These sophisticated systems enhanced the performance of the DC-10, enabling more accurate tracking and quicker adjustments during landing.

The aircraft also boasted an advanced hydraulic system that was integral to flight control. Hydraulic power, derived from engine-driven pumps, actuated many of the flight control surfaces. The critical nature of these hydraulic circuits led to the inclusion of hydraulic fuses to prevent total fluid loss, further enhancing safety.

Different Variants

The DC-10 saw several iterations, each offering unique features and advancements.

1. DC-10-10: This is the initial passenger version introduced in 1971 and was equipped with GE CF6-6 engines.
2. DC-10-10CF: This version was a convertible passenger and cargo transport variant of the DC-10-10.
3. DC-10-15: Specifically designed for use at high altitude and high temperature (hot and high) airports. This variant was similar to the DC-10-10 but equipped with higher-thrust GE CF6-50C2F engines.
4. DC-10-30: A long-range model equipped with GE CF6-50 turbofan engines, larger fuel tanks, a larger wingspan, and a set of rear center landing gear to support the increased weight.
5. DC-10-30CF: This was the convertible cargo/passenger transport version of the DC-10-30.
6. DC-10-30ER: This variant is an extended-range version of the DC-10-30, boasting a higher maximum takeoff weight and an additional fuel tank.
7. DC-10-30AF: Also known as the DC-10-30F, this version was the all-cargo variant of the DC-10-30.
8. DC-10-40: The first long-range version fitted with Pratt & Whitney JT9D engines, designed with a higher maximum takeoff weight and more powerful engines.

Characteristic	DC-10-10	DC-10-30	DC-10-40
Cockpit Crew	Three	Three	Three
Standard Seating	270 (222Y 8-abreast @ 34″ + 48J 6-abreast @ 38″)	Same as -10	Same as -10
Maximum Seating	399Y (10-abreast @ 29–34″ pitch) layout, FAA exit limit: 380	Same as -10	Same as -10
Cargo	26 LD3 layout, main deck: 22 88×125″ or 30 88×108″ pallets	Same as -10	Same as -10
Length	182 ft 3.1 in / 55.55 m	181 ft 7.2 in / 55.35 m	182 ft 2.6 in / 55.54 m
Height	57 ft 6 in / 17.53 m	57 ft 7 in / 17.55 m	Same as -30
Wingspan	155 ft 4 in / 47.35 m	165 ft 4 in / 50.39 m	Same as -30
Wing Area	3,550 sq ft (330 m2)	3,647 sq ft (338.8 m2)	Same as -30
Width	19 ft 9 in (6.02 m) fuselage, 224 in (569 cm) interior	Same as -10	Same as -10
Operating Empty Weight (OEW)	240,171 lb / 108,940 kg	266,191 lb / 120,742 kg	270,213 lb / 122,567 kg
Maximum Takeoff Weight (MTOW)	430,000 lb / 195,045 kg	555,000 lb / 251,744 kg	Same as -30
Maximum Payload	94,829 lb / 43,014 kg	101,809 lb / 46,180 kg	97,787 lb / 44,356 kg
Fuel Capacity	21,762 US gal / 82,376 L	36,652 US gal / 137,509 L	Same as -30
Engine Model	GE CF6-6D	GE CF6-50C	PW JT9D-20 / -59A
Engine Thrust	40,000 lbf / 177.92 kN	51,000 lbf / 226.85 kN	53,000 lbf / 235.74 kN
Cruise Speed	Mach 0.82 (473 kn; 876 km/h) typical, Mach 0.88 (507 kn; 940 km/h) MMo	Same as -10	Same as -10
Range	3,500 nmi (6,500 km)	5,200 nmi (9,600 km)	5,100 nmi (9,400 km)
Takeoff	9,000 ft (2,700 m)	10,500 ft (3,200 m)	9,500 ft (2,900 m)
Ceiling	42,000 ft (12,800 m)	Same as -10	Same as -10

History of the DC-10

American Airlines’ announcement to choose the DC-10 over the similar L1011 Tri-Star from Lockheed was a surprise, launching the DC-10 project with the Rolls Royce RB211 engine. The first-ever variant, the DC-10-10, was designed for domestic flights, boasting a 6,100-kilometer (or 3,800 miles) range. Its maiden flight took place on August 29, 1970, paving the way for the aircraft’s commercial debut on August 5, 1971.

With time, the DC-10 evolved to cater to diverse flight needs. The DC-10-15, known for its powerful engines, was designed for hot and high airports. The DC-10-30 and −40 models, equipped with an additional main landing gear leg to support higher weights, had intercontinental ranges of up to 9,600 kilometers (or 5,200 nmi).

Hurdles and Triumphs

Despite its promising start, the DC-10 faced a number of obstacles. It suffered from an early reputation for being unsafe and uneconomical, further hampered by the simultaneous introduction of Lockheed’s L1011 Tri-Star. The competing model was similar to the DC-10, leading to a diluted market. Although the DC-10 was less expensive, initial sales were sluggish due to safety concerns.

Issues with the design of the cargo door were a significant part of the aircraft’s early safety woes. Unlike most aircraft, where cargo doors open inwards, the DC-10’s cargo door opened outwards. This design had its advantages but also led to a number of serious incidents.

However, in the face of adversity, the DC-10 proved its mettle. After these incidents, modifications were made, the design was improved, and the cargo door issue was successfully resolved. In spite of the initial safety concerns, the DC-10 started to amass safe flying hours, and sales began to pick up.

Over the years, the McDonnell Douglas DC-10 has demonstrated its resilience and adaptability. The aircraft has been used in various capacities, including as a mid-air refueling aircraft in the U.S. armed forces. Its diverse use and long history of service underscore the significant role it has played in aviation.