Airtest – BAe125-700

The recent arrival in Australia of British Aerospace’s demonstrator 125-700, G-OBAE, a cool $A 5. 6 million worth of sophisticated long-ranging excellence, marked the latest chapter in a star-studded story which had its roots embedded deep in experience gained through the gentle DH Dove – a well-loved sight in yesterday’s Australia skies.

The story isn’t overlong and well worth recounting, those stepping stones to today’s 700 Series . . .

The dainty twin-motor Dove, which endeared itself to civil and military pilots alike during its long life, was a reliable money-spinner in North America during its early years.

Jet airliners were appearing in increasing numbers around 1959, and forward planning at Hatfield logically concluded that an executive jet with internal walkround capability would be needed in the not-too-distant future.

Accordingly, the de Havilland Board, then still independent of the Hawker Siddeley Group, made a decision in March 1961 to embark on a bold project.

The public was told in April that year; that an extensive survey of the market and its needs had evolved a plan – following project studies – to manufacture as a privately funded venture.

That plan, made in the still-burgeoning days of private enterprise which made Britain the envy of the world, was built around a general configuration for a six-seat aircraft powered by a brace of Bristol-Siddeley Viper 20s.

The type was to be named the Jet Dragon, a noble gesture designed to perpetuate the memory of de Havilland’s dearly-loved 1932 first twin-motor type, the DH 84 Dragon.

The new Viper-powered twin was, in the words of the original release, to be “built to meet the demands of the business executive for much higher standards of speed and comfort . . . “, to keep operating costs down to a level comparable to the conventional aircraft of similar size, and to “provide world travel at 500 mph. ” Design work had begun a year before the public announcement, with the first flight of the two prototypes dated August 13 and December 12, 1962. The first prototype wingspanned at 44ft and measured 46ft Sin in length.

A primary production batch of 30 Series 1 125s was ordered following the successful prototypes’ flights, with wingspan increased by three feet and lengthened by a foot.

First production rollout and first flight arrived on February 12, 1963 – a proud moment indeed.

The first eight in the initial production batch were designated Series 1, grossing at 20,000 lbs and fitted with Viper 520s of 3,000 lbs static thrust.

North America was one of the prime demonstrators and marketing targets. In August 1964 the offensive was launched – an intensive 105-city demonstration tour lasting 110 days. It was exacting, exciting and exhausting, but by the end of the demo slots, there were 22 orders on the books.

Rollouts from Hatfield following the first eight production 125 Series 1 s were labelled Series 1 A or 1B, depending on whether they were destined for the US (A) or elsewhere.

As the Series 1 progressed it was re-engined with the more powerful Viper 521 (3,120 lb/st. thrust) and then the Viper 522 with 3,360 lbs of static urge. Gross went up to 21,200 lbs.

The Royal Air Force joined the list of customers, their specially-equipped 20 125s being given the Series 2 designation and originally bearing the name of Dominie T. Mk. 1. Most of us flew the older de Havilland Dominie at one stage of our Service lives and knew them as patient, docile and forgiving beasts.

But the dear old biplane in which we sweated away at twin-engine handling exercises before going to the terribly modern Anson and out-of-this-world Oxford bore little resemblance to the Viper-powered nav. Trainers which initially bore the same illustrious name . . .

As executive’s needs experience increased, so did the Series; the Series 3 (in A and B versions) carried an increased gross weight of 21,700 lbs plus a revamped electrical system and air-conditioning refinements.

Some Threes were offered with a ventral fairing long-range tank holding an extra 112 Imperial gallons of fuel. These Series 3A-R and 3B-R grossed at 22,800 lbs, and from our records, one Series 1 B was similarly fitted as more buyers reached out for more range to help shrink the business world still further.

Series 4, born in the autumn of ’68, showed the results of more North American market research; the single-digit Series number became 400; integral steps sprouted in the main entrance door; flush aerials provided a more streamlined look to an undeniably dumpy-looking aircraft and flight deck revamping was apparent.

With the Viper 522s installed, the Series 400 grossed at 23,300 lbs. The American-marketed 125-400A was undoubtedly the biggest seller to that time; more than 65 were sold “over there,” with the first 42 delivered as DH-125s and the rest as BH-125s following the agreement between Hawker Siddeley and Beech Aircraft in 1969 for joint marketing.

In fact, the Series 400 was then the biggest seller all told; in 1968 orders were taken for 50, with 44 more the following year.

Then came the Series 600A and B. During the 125’s teenage life, continuous engineering developments were in train. The 600 featured improved capacity, performance, handling flight deck and systems updates.

Most noticeable externally was the 2ft plug forward of the wing leading edge, taking in an extra window and providing two more seats inside the fuselage. Layouts were available for up to 14 passengers, and refurbished cabin walls and floor giving still more space inside this portly adolescent from HS.

Most significant of all, the older Vipers were replaced with Viper 601-22 turbojets, each rated at 3,750 lbs. This hiked gross up to 25,000 lbs, range stretched out to 1630 nm at long-range cruise, and length with the fuselage plug went out to 50ft 5¾ in.

Maximum operating speed was at that time a healthy 312 knots indicated, max Mach number 0. 78.

Came the turning point; Hawker Siddeley designers surveyed the options open in the 1973-1975 “window. ” They had already seen that to remain in the market they had to go turbofan . . .

There were broadly two main powerplant choices:

• General Electric’s CF 700 was already getting relatively long in the tooth.

• Garrett’s ATF dash 3 seemed unlikely to be developed for civil use.

Added to that the Garrett TFE731-2 was just a shade lacking in power, taking into account forward projections for the Series 700.

On top of that, there had been the 1974 oil crisis which threw into sharp focus the need for less thirsty engines. Environmentalists were beginning to make a fuss about these noisy things which flew over their world. . .

Garrett eventually came up with its 731-3 at the right time, a turbofan that filled the needs of HS requirements for fuel economy and Good Neighbour characteristics.

Series 600 G-BFAN was chosen as the turbofan demonstrator and it flew on June 28, 1976, with a Garrett Air-Research TFE731-3 on each side.

Trials proved a number of dramatic things, chiefly a great increase in economy and a 50 per cent reduction in sideline noise levels. Hot and high trials exceeded expectations.

The whole concept was so successful that HS decided to initiate a definitive Series 700 which made its first flight in November 1976.

With the market reviving after the ’74 oil crisis slump, the Series 700 found its niche. True, it was outsold by the Learjet, but outranged types including the Falcon 20 and Sabre 75A, had bigger cabin volume than the Westwind 1124 and Learjet 36, and were up to 35 per cent cheaper than the Jet Star II and Gulfstream II.

The 125-700 philosophy is built largely around the fact that as range increases, so does the need to walk around the passenger cabin in as much comfort as possible during a flight which could last up to five hours, sometimes six.

In this respect, much thought and practical engineering has gone into the flight deck environment. Now the child of British Aerospace Public Company Limited and being produced by the Hatfield-Chester Division of BAe, the overall Series has come a long way since that first customer delivery back in 1964 to Swiss charter co-operator Chartag.

The accent throughout has been in the buoyant export market where an estimated 80 per cent of all 125 sales have been recorded. Sixty-two per cent of total production has been sold in North America.

So how does the Series 700 differ from the earlier models? There’s been a deal of aerodynamic cleaning up, generally reducing skin drag by countersinking and fairing-in aerials, etc.

The Garretts are now housed in Grumman Aerospace-designed cowlings which in turn provide 12 per cent more inlet area. Pylon depth has been reduced by about 25 per cent. On the flying side, the rudder bias system has been duplicated; although the Garretts deliver less thrust than the old Vipers, relative engine-out thrust asymmetry has gone up by about half.

About 350 hours were flown on the prototype and the No. 1 production Series 700 confirmed the best bit – the range has spread to a very respectable 2520 nautical miles including VFR reserve.

Maximum take-off weight is now 25,500 lbs, Maximum operating Mach no. is 0. 77 or 0. 78, depending if you’re flying on a British or North American certificate.

Briefing by BAe’s Graham Reith (ex-RAF Britannias, ex-McAlpine 125 skipper and now BAe 125 sales executive Far East), Captains lain Porteous (bearer of a noble name!) and George Ellis – both ex-Royal Air Force and ETPS products; Engineer Tom Stevens, and BAe’s Man in Australia Ken Davies, brought to light many salient “newies”, confirmed during walkround.

• New entry door, flight deck canopy and the 2ft plug inserted in the fuselage, much new bonding reducing structure weight.

• The Garretts are fitted with an APR (Automatic Performance Reserve system) which basically allows the thrust of one or both engines to be pushed to a higher-than-normal rating in emergencies.

• The APU has been designed to provide its own power for electrical power and air-conditioning while groundborne.

• Total usable fuel totals 1180 Imperial gallons – 1020 in the wing tanks, 109 in the ventral tank and 51 squeezed into the dorsal.

All tanks can be refuelled from a single airliner-type pressure refuelling point in the lower starboard side of the rear fuselage.

• Big double-slotted flaps, safeguarded against asymmetric operation by an asymmetric sensing cross-connection, come down on operation of a gated control – normal ranges are 0-15 for take-off, 15-25 for approach and 45 for landing.

The double-slotted flaps and high flap angle give the Series 700 an 81-knot stalling speed and excellent handling characteristics during approach, round-out and touch.

• Airbrakes and lift dumpers are standard and efficient.

• Two rudder bias struts automatically apply deflection during engine-out conditions, low-pressure air impinging on one side of an equal-area piston to minimise pilot bootload.

• Full ice protection is standard And, according to H. C. Sleigh’s Manager, Marketing Division, John South, who formed part of the BAe demonstrator team at Sydney Airport during AUSTRALIAN AVIATION’s evaluation, the Series 700’s noise footprint is more than silent enough to satisfy regulations – sideline 88. 9 EPNdb, take-off 87. 6 and approach 96. 3.

The Series 700 125 we evaluated, replete with options, worked out to about £3. 075m; that’s about $A5. 6m.

The flight out to Sydney from UK, said Graham Reith, had included stops at Dubai, Ceylon (Sri Lanka), Singapore and Darwin. Using the Global GNS, its accuracy had been proved on the longest hop by a maximum error of about 2. 8 nm. Graham gave our team the latest Series 700 sales figure as we climbed aboard – 176 at last count, generally about 60 per cent to North America, the rest “elsewhere”.

“Elsewhere” included 20 to McAlpine, the world’s biggest charter operator; 20 to the Royal Air Force as navigator trainers and six to the VIP Flight; other 125s fly target sorties for the Netherlands Navy, casevac in Europe and others in high-altitude photographic roles.

In the cockpit – sorry, on the flight deck of the Series 700 demonstrator (like all marketers, Graham Reith was quick to point out the symbolism in the ident letters – Go BAe), the panel was something quite different from the Bell Bros 125 we had first sampled years ago in Western Australia.

Avionics abound – standard fittings include Collins FCS-80 autopilot and dual FDS and an air data system; ADF 1 and 2 by Collins, transponder, DME, VHF-NAY, Collins WXR-300 slimline weather radar and a host of extras.

Depending on your needs, these could cover Litton-211 Omega/VLF, Global 500A-2 ditto, a Canadian Marconi CMA-734 Omega, Delco Carousel inertial navigator or a Litton, UCDD flight data recorder with either/an underwater sonar beacon and VHF-COIM PIT event marker, and everything else from the ship-shore phone, to stereo systems, a video entertainment system – and an electronic typewriter.

They think of just about everything, these British . . . Despite this fiendishly long list, the flight deck panel has room for more and is set out in logical fashion.

The overhead covers power, electrical and engine start controls. Two flight guidance panels, altitude more alert and autopilot boxes sit on the centre coaming.

Engine gauges, radar and master warn indicator annunciator to hold pride of place on the centre panel, with VHF Comm/nav/DME beneath. Below that come the long-range navigator, HF and transponder, just above the power quadrant. It was a cool +16C when we completed the start checks and released brakes. Take-off weight at the holding point was computed at 22,500 lbs with nine p. o. b. , – about 3,000 lbs under gross.

Cleared for a radar departure, we rolled at 19 past the hour in brisk fashion, crisp acceleration and exhilaration being the two words most likely to describe the unstick. Arrived at 140 knots and was gone. Fifteen degrees of flap came up gently with no pitch change, wheels were tucked away and we speared heavenwards at 2000fpm, winding up to 3000fpm with 220 on the clock. N1 sat very nicely on 94/95 per cent, interstage turbine temperature steady on 840/846 and N2 at 97 per cent.

At 5000 feet we got a “Go” from Sydney to turn onto zero nine zero and get up there to 10,000ft. The VSI clocked a steady 2250 fpm en route, with IAS at 235 knots.

A quick readout at transition height showed 85 per cent, 714 and 92 from top to bottom, and IAS sitting on 272 knots.

We could already appreciate the silent environment, the loudest noise on the flight deck being airflow hiss. Between conversations, our cabin team noted a low airflow rumble which mingled with the dimly-heard Garretts doing their stuff astern.

This, then, is what BAe call realism; with Air Data Modes engaged, flying at a speed (at our height) not tar oft the Mach 0. 77 V mo for British-registered 125s. Fuel flow was steady on 750 lbs, IAS was 270, N 1 90 per cent, ITT 658 and N, also 90 per cent.

With the traditional inherent “feel” of reliable grace, Rolls-Bentley dignity and a great sense of solidity coming through the entire airframe and controls, one could well understand why BAe, after much research, retain the basic structure in the Series 700.

For the record, the complete structure is designed for a minimum life without damage of 20,000 flights. That’s equal to two daily for more than 30 years!

In fact, one aircraft delivered back in ’66 has completed 30,000 cycles as a crew trainer and has been cleared to 50,000 landings – with 75 per cent of these being touch and go. ”

Back in the cabin, our passengers lounged and talked of this and that, occasionally glancing at the rear bulkhead digital readout of time and ground speed.

They sat on suede leather fabric amid a yellow metal and brown-gold interior.

What better way can the Man of Decision travel? Up front there was little to do apart from answering Sydney’s commands and letting the aircraft fly itself home through the pretty solid cloud – it was that sort of a day.

We had time to natter with George Ellis during our initial descent and subsequent hold by Sydney. He confirmed the aircraft’s overall excellence, speaking as a qualified graduate of that august establishment, the Empire Test Pilots’ School.

If one had to stall a Series 700, one would expect to get a healthy wing drop. Deep stalls were still being explored by a specialist production test team in the UK. A stick shaker operates about 8 per cent above stalling speed, actuated by a pressure sensing point under each wing.

We marvelled again at the avionics and navigation, gear, noting in passing that the left ram’s horn on the stick had five buttons intercom autopilot/flight director sync go-round button; autopilot disconnect and pitch trim – before letting the legitimate two pilots land at Sydney.

The landing run was short indeed, with both pilots applying full arm/elbow lock to keep the nosewheel on. A customer option is Aeronca thrust reversers.

Post-flight briefing rammed home the word “realism” so well plugged by BAe in their Series 700 marketing drive. With long legs at high speed, in utter comfort, the 125-700B can cut fuel payload on shorter legs to make off-bitumen and short runway operation things of safety and ease.

With the Garretts working on a progressive maintenance program, and giving the Series 700 a 30 per cent fuel saving and 50 per cent increase i,n range over previous 125 models, plus product support from people like H. C. Sleigh, the Series 700 looks set fair to give the Australian market a nasty nudge – and not just by virtue of a good name, either.

With legs long enough to cover the entire Australian continent, reach out to places like New Zealand and Indonesia, and boast a genuine intercontinental range, BAe’s 125 Series 700 has more than just a lot going for it in terms of down-to-earth realism in the aerodynamic, engineering arid financial fields.