Story ID: 030
De Havilland's DH.125—Britain’s Long-lived Bizjet
By: David Donald
Caption: Various versions of the jet were produced for more than 50 years
Word Count: 1922
What began life as the de Havilland DH.125 Jet Dragon was a leader in the first tranche of business jet designs that emerged in the late 1950s and early 1960s. Like a number of its counterparts, it came to be known by a plethora of names and designations as the ownership of its design changed hands. Although no longer in production, the type—in its most recent Hawker 800/850/900 guises—remains an important part of the business jet scene.
One of the most famous names in UK aircraft manufacturing, de Havilland had begun building aircraft during World War I but had found popular fame in the interwar period with its Moth series of private aircraft. During World War II, many Commonwealth pilots learned to fly in Tiger Moth trainers, while the twin-engine Mosquito light bomber/fighter was one of the conflict’s most effective aircraft.
In the post-war period, the design team that had created the Mosquito went on to produce one of the UK’s greatest technological achievements: the DH.106 Comet, the world’s first jet-powered airliner. The same team also created the DH.104 Dove, a light twin piston-engine airliner that became one of the company’s greatest post-war successes. Intended for regional carriers, the Dove found favor among the growing business aviation community, and several notable companies equipped their new corporate flight departments with the Dove. The type remained in production until 1967.
By that time, however, the corporate aviation sector was in the grip of a new revolution. In 1957, Lockheed flew its four-engine JetStar, and North American Aviation flew the Sabreliner a year later. While both types were initially designed to meet military requirements, they achieved success in the corporate aviation world. The business jet had arrived.
Enter the Dragon
Spurred by the arrival of these two aircraft, and with a clear need to create a replacement for the Dove, De Havilland set to work in 1961 to design a twinjet aircraft that could meet the needs of companies and wealthy private customers. The result was the DH.125, which was initially given the name Jet Dragon. That name, although it was dropped at an early stage, harkened back to the company’s successful Dragon and Dragon Rapide twin-engined biplanes of the 1930s.
With two 2,500-pound thrust Bristol Siddeley Viper 511 turbojets mounted on the rear fuselage, the DH.125 had a slightly swept wing that mirrored the planform of the wing developed for the Comet. The wing was a one-piece unit that was mounted below the fuselage, ensuring that the six-seat cabin area remained unobstructed. Double-slotted flaps were installed for good short-field performance.
The initial design featured a T-tail, but an additional fin area was subsequently added above the original. A ventral skid was added to provide some protection in the case of a wheels-up landing.
Two prototypes were built at Hawarden near Chester—also known as Broughton—which was the primary manufacturing site. The prototypes were assembled and completed at de Havilland’s Hatfield airfield, from where the first prototype DH125 (G-ARYA) made its initial flight on Aug. 13, 1962. The second, sporting numerous changes and more equipment, took to the air on December 12. Initial flight trials were encouraging; the DH.125 exceeded its design range of 1,000 miles by double the amount.
On Feb. 12, 1963, the third aircraft (G-ARYC) was flown. It was the first production-representative aircraft and the first to be completed and flown from the Chester site. It was longer and had greater wingspan than the prototypes, and in July 1963 it was handed over to Bristol Siddeley for testing of the production powerplant, the 3,000-pound Viper 520.
After undertaking numerous sales trips and demonstrations—including visiting 16 countries in a day in May 1964—the aircraft was subsequently employed as a shuttle between Filton and Toulouse during the development of the Concorde’s Olympus 593 engine. Today, G-ARYC is on display at the De Havilland Aircraft Museum at London Colney. The second prototype also survives with the Midland Air Museum at Coventry’s Baginton airfield.
Distinctive upper-wing fences were introduced on the second production aircraft, and a further six were produced to complete Series 1 production. Following were the Series 1A (for North America) and 1B (for the rest of the world). The main external difference was the reduction in cabin windows from six to five to reduce cabin noise, while the aircraft also had upgraded 3,120-pound thrust Viper 521s.
Series 1A aircraft were ferried across the Atlantic with temporary avionics to two U.S. distributors (Atlantic Aviation and AiResearch) and a single Canadian distributor (Trimmins), which outfitted the aircraft to customer specifications. Altogether, 62 Series 1As were built and sixteen 1Bs.
 The First Name Change
Even before the DH.125 had flown, De Havilland had been swallowed up into the Hawker Siddeley Group, but it was not until 1964 that the type’s designation was officially changed to HS.125. That change did not apply in North America, however, where the DH.125 was by then a well-known type.
In 1963, the type notched up its first military sale, when the Royal Air Force ordered 20 aircraft for use as navigation trainers. Although designated as Series 2 production, they were essentially Series 1B aircraft but with six windows to port and four to starboard. They also had a ventral strake added below the fin. The first flew in September 1964, and the type began service in March the following year. In RAF use, the type was known as the Dominie T.Mk 1, and it operated until 2011.
An increase in mtow and 3,360-pound-thrust Viper 522 engines were the main features of the Series 3, of which 30 were built in A and B versions. The 34 aircraft built as Series 3A/RA and 3B/RA had an additional 112 gallons of fuel in a ventral tank. Some Series 1 aircraft were partially upgraded to Series 3 standards, and many Series 3s were later re-engined with Garrett (now Honeywell) TFE731 turbofans.
Further weight increases and the installation of an outward-opening cabin door were introduced by the Series 400, of which 117 were built. From 1970, Beechcraft became Hawker Siddeley’s U.S. sales partner, and the aircraft was marketed as the Beechcraft Hawker BH.125.
The next model, the Series 600, represented a considerable development. The cabin was stretched to accommodate up to 10 passengers, with six windows per side, and the engine—by then a Rolls-Royce product—was the 3,750-pound-thrust Viper 601-22. Seventy were built, split equally between North American markets and the rest of the world.
At the time, the Viper turbojet was becoming obsolete, and a change to turbofan power was becoming vital. The result was the Series 700, which was to be Hawker Siddeley’s final development. First flying on June 19, 1976, the HS.125-700 was powered by the Garrett TFE731-3RH turbofan but was otherwise generally similar to the Series 600s. Production reached 215, of which 151 went to the U.S. and Canada.
In 1977, Hawker Siddeley became part of the merged British Aerospace conglomerate, and the HS.125 became the BAe 125. Production continued at Chester, as did development, now under the auspices of BAe’s Corporate Jets division. The first British Aerospace version was the BAe 125-800, which took to the air for the first time on May 26, 1983. It had an increased wingspan, a more streamlined nose profile, a redesigned curved windscreen, increased fuel capacity, and 4,300-pound-thrust TFE751-5R-1H engines. It was notable for being the first business jet to feature an EFIS cockpit and was a runaway sales success.
While 125s had always been acquired in small numbers by the military for liaison/VIP transport duties, the 125-800 was the first to spawn special-mission versions. The U.S. Air Force acquired the type as the C-29A to conduct the combat flight inspection and navigation mission, checking navigational and landing aids at air bases. Japan bought a similar aircraft (designated U-125), as well as U-125As for long-range search-and-rescue, equipped with APS-134 search radar and a large port-side observation window. The Republic of Korea Air Force acquired two RC-800 special-mission versions for multi-sensor reconnaissance and signals intelligence gathering.
In the meantime, British Aerospace had introduced an intercontinental version, the BAe 125-1000. This had increased fuel capacity and a fuselage stretched by 2 feet, 9 inches that could accommodate up to 15 passengers. It first flew on June 16, 1990, on the power of 5,200-pound-thrust Pratt & Whitney Canada PW305 turbofans. Sales were sluggish, and only 52 were built.
 U.S. Ownership
In 1992, BAe announced a major restructuring that saw some of its major assets sold off. Among them was the Corporate Jets division. With its longstanding sales relationship with BAe, Raytheon (which had acquired Beech in 1980) was a natural buyer, and the 125 line became the property of the newly formed Raytheon Aircraft in June 1993.
While manufacturing of the slow-selling Hawker 1000 (125-1000) ended in 1997, the main prize was the hugely popular 125-800—eventually the Hawker 800. Manufacturing continued in the UK at Chester, with near-complete fuselage and wing sections being transported to Beech’s Wichita facility for final assembly and completion. In 1998, a Hawker 800 became the 1,000th aircraft of the 125 family to be delivered.
Raytheon sold the business to Hawker Beechcraft in 2007, but not before new models had been launched. Powered by the 4,660-pound-thrust TFE731-5BR1H engine, the Hawker 800XP followed on from around 275 model 800s. A number were subsequently modified with Aviation Partners winglets, leading to the Hawker 850XP, which was an 800 with factory-installed winglets.
Announced in 2007 were the Hawker 750 and 900XP. The first was a low-cost, lightweight version with a revised interior and baggage pannier replacing the ventral fuel tank. It accounted for 48 aircraft. The Hawker 900XP was an 850XP tailored for longer-range and hot-and-high operations. It had modified avionics and TFE731-50R engines.
Production abruptly ceased in 2013 with the bankruptcy of Hawker Beechcraft. Around 1,700 125/Hawker aircraft had been built by that time. While the reborn Beechcraft Corporation restarted building its turboprop designs, there was no intention to reinstate bizjet production as new owner Textron Aviation already had the Cessna line. However, the company continues to provide OEM support for the Hawker line to this day.
With the ending of Hawker manufacture, the curtains closed on what had been one of the longest-running business jet production lines: DH.125-derived aircraft were built for more than 50 years. The Hawker 800 family continues to be a stalwart of the sector today with a healthy preowned market and upgrades such as Collins Pro Line 21 avionics available.
Beginning life as one of the “founding fathers” of the business jet scene, the DH.125 and its derivatives notched up several “firsts” along the way, not least of which was being the first to introduce a glass cockpit. A less welcome event was when a 125 became the first and only business jet to have been hijacked. This occurred in 1967 when an armed French agent took over the chartered aircraft carrying Congolese Prime Minister Moise Tshombe and forced it to divert to Algeria, where he was imprisoned.
Another notable event involving a head of state occurred in August 1988, when a 125-800 carrying Botswana’s President Quett Masire was hit by an air-to-air missile fired by an Angolan MiG-23. The missile, which had been launched inadvertently, caused considerable damage, including the loss of an engine, but the BAe pilot flying the aircraft managed to land safely.