Flight Test: De Havilland DH.84 Dragon
The takeoff run is uphill on wet grass in an aircraft weighing well over a ton with 260hp on a good day ? so it’s not going to be quick. Henry, my host, tells the story of a departure from Berlin Tegel where he was asked to make an immediate turn and climb to avoid a noise sensitive area. His reply was that they could have one or the other but not both. He warns me it’s not difficult to fly, just “different”.
I’ve been tasked with comparing the DH84 Dragon to a modern executive jet. I should really use the Jet Dragon (if you don’t recognise the name, look on Wikipedia). However, it’s been 23 years since I’ve flown one and my work machine is an Airbus ACJ319 which ? apart from having two engines and being aeroplane-shaped ? is incomparable, so let’s use the Lear 45 instead.
HILLMAN’S AERIAL ‘SALOON COACH’
In the early 1930s Mr Edward Hillman, of the snappily named Hillmans Airways and Saloon Coaches Ltd was running the DH83 Fox Moth and wanted de Havilland to design a twin-engined aircraft to operate from the southern UK to Paris as cheaply as possible. At the same time, the Iraqi Air Force was looking for a machine to quell local disturbances and carry out patrol and communication flying, and so the Dragon was hatched.
Mr Hillman took his first delivery in 1932. It cost £2,795 (approximately £165,000 in today’s money) and carried six to eight people. Although Hillmans’ were low-cost, the only fares I have been able to find are for Railway Air Services Ltd’s Plymouth to Birmingham route. The price was 60 shillings (£3), the average wage in 1932 being just over one shilling an hour.
The DH84 Dragon is now a very rare machine and Sir Torquil Norman (www.torquilnorman.com) has very generously allowed us to fly his. Henry Labouchere maintains and, along with Sir Torquil, flies G-ECAN. The machine is a late-build example imported from Australia, leaving its nest in March 1943.
The sun is now shining and it is time to get the Dragon from its lair. Henry takes the controls, whilst I fly the camera ship. Once that task is done, it’s my turn to tame the beast.
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My first impressions are that the Dragon must be similar in size to the Lear. A check of the figures reveals how close they are: at 34ft 6in the Dragon is shorter than the Lear’s 58 feet. However, the biplane’s wing span is only six inches narrower than the jet’s, at 47ft 4in. The high tail of the 45 gives it a 4ft height advantage, but the DH84 has a greater wing area of 376sq ft, compared to the Lear’s 311sq ft. The Lear 45 also costs a little more ? about US$12m at the end of production in 2012.
STEPS AND CLAMSHELLS
Climbing on board the Dragon requires a large step up onto the port lower wing (steps would have been provided for normal operation). Climbing through the doorway we see to the right a baggage area ? or two extra seats, depending on fit ? to the left six leather-covered seats and a centre aisle leading to the teardrop-shaped entrance to the flight deck.
In comparison, the Lear is boarded through a clamshell door at the front of the fuselage, the lower half acting as steps. Immediately in front is a refreshment centre, whilst to the right the seats of the main cabin are, again, leather, but are larger and move in all directions. To the left is the flight deck, here both aircraft are similar: entry in either case requires a certain dexterity and skill. In the 45 I step over, and to the left of the central pedestal and seat ? being careful not to knock any switches ? and lower myself into the seat. At 5ft 11in, my head just misses the ceiling even with the seat fully lowered. The rudder pedals can be moved electrically. The Dragon also requires care when climbing in, but this time it is the left leg that could do the damage as it swings around the control column, being careful to avoid the rudder trim lever as you sit in the single central seat. Neither the rudder bar nor the seat have any adjustment, but because Sir Torquil and Henry are tall with long legs the former has been modified, which means I now need a cushion to move me far enough forward to get full rudder travel without stretching.
Before starting the external checks I make sure that both sets of mags are switched off and everything else looks normal on the flight deck. The Lear has a slightly longer check with thirteen items needing attention before going to look at the exterior.
When the Dragon was new it would have been a two-crew aircraft; pilot and mechanic. The latter would have been a man of many trades ? aircraft engineer, baggage loader, cleaner etc. Today it’s just Henry and me carrying out a walk-around, and no baggage or cleaning to worry about. Although the Learjet uses two crew, the second pilot is just that; both of us taking turns to load, clean and make the coffee!
From the Dragon’s entry door, the fuel gauge can be seen on top of the engine nacelle just aft of the fuel filler cap. There is also a non-standard auxiliary tank of 94 litres in the rear of the aircraft, but it is only used for long range flights and filled to a maximum of sixty litres with just the pilot on board to keep within C of G limits. The flying wires and turnbuckles are checked in standard biplane fashion. This is a stunning restoration and everything is clean and properly adjusted. There might not be any bracing wires or struts on the 45, but on the leading edge there are ‘vortilons’. These are not alien stowaways, but four small fences that come out from the leading edge of each wing to control span-wise airflow.
The Dragon can fold its wings, so it is essential that they are locked properly and checked. The Lear of course does not have this feature unless you go very, very fast or pull very, very hard! The Lear has beautifully finished wings, manufactured from a solid sheet of aluminium by de Havilland in Toronto; a family connection. The Dragon’s main wheels are covered by polished spats or wheel pants. I ask if they attract mud but Henry says not, although not every Dragon was fitted with them. No such problems with the 45 although it’s a low-set aircraft and you need to bend or even lie down to look at the main wheel bay.
Refuelling the Learjet is simpler than the Dragon; the fueller connects a high pressure pipe to the refuelling point on the right side of the fuselage, just behind the wing root, and then puts in the required amount. The three tanks are interconnected and filled through one point (there is also a standard gravity fuel point if aircraft power is unavailable but it’s a very slow fill). The Dragon of course requires each tank to be filled individually.
With external checks complete let’s jump into the cockpits. The Dragon’s flight deck is functional from a time when going flying was just a matter of taking off from the field, pointing the aircraft in the right direction and trying to avoid the clouds and hills. Seated in (or should that be on?) the Dragon you get a very good view for a taildragger ? certainly better than from a Stearman or Waco.
By my left shoulder is an electrical panel, not 1930s standard fit, but a worthwhile modification. Below this are the two levers for the fuel system. “Do not touch,” says Henry, “they stay on.” The auxiliary tank is not used unless going for maximum range. Moving forward are a radio and transponder, just to their right ? by the seat ? is a long black brake lever, cable operated to drums, so only really of use for manoeuvring while taxying.
POLISHED THROTTLE LEVERS
Just below the window line are the two polished throttle levers with a friction nut, forward of these are the mixture controls, their yellow knobs prevented from being moved back to the weak or cut-off position by a hinged gate; another Henry modification. Next to my left thigh is the trim wheel, very similar to the one in the Chipmunk, but with up and down shown by a small red mark on the block that travels left and right.
The main instrument panel is very simple and well laid out with magneto switches, oil pressure gauge, a compass, altimeter, airspeed indicator, direction indicator and artificial horizon, with a slip indicator on the far right. A removable GPS mount is clamped to the right side wall and then finally the rudder trim lever is on the central tunnel, near the base of the control column. There are no position indicators and it would be easy to knock it when climbing aboard.
Sitting in the Lear’s left seat there is also an electrical panel on the sidewall, but this is a simply a circuit-breaker panel. The instrument panel has a Honeywell Primus 1000 Electronic Flight Information System (EFIS) and Engine Instrument and Crew Alerting System with radios and pneumatic system switches. The central pedestal is home to system test switches, throttles, spoilers, flaps and speedbrakes, aft of which are the Flight Management System (FMS), trim control panel, HF, weather radar, auxiliary power unit (if fitted), engine controls, fuel panel, and fire system.
TIME TO GO FLYING
Back in the Dragon, it’s time to fly. We are starting in the original way: my man waiting for the captain’s order before stepping forward to swing first the starboard propeller, then the port. Both engines fire on the first swing and Henry is soon aboard, confirming all is well outside and that the cabin door is secure. The RPM indicators are on each engine cowling and the only other indication that all is okay with the Gipsies comes from the oil pressure gauges on the left side of the panel. It all seems very bare compared with a modern aircraft and I keep thinking I’ve missed something.
Checking that all is clear around us, I release the brake, and as I gently increase power we move off. A brake check proves they work and we taxi downhill to the north-east corner of the field. This is where three hands are useful; one for throttles, one for brake (no foot brakes) and one to hold the control column in the correct position. It’s a downhill taxi on wet grass and I do it slowly.
Once in position, each throttle is advanced and mags checked. I then carry out a flight control check and a final left-to-right scan around the cockpit to make sure all is as it should be.
I gently advance the throttles, and despite the tail wheel lock and my leading with the right throttle, immediately a swing develops. I stop and reposition the Dragon at the start of the takeoff run. This time I lead with lots of right throttle and, once we are straight, bring both engines to full power. Acceleration is leisurely and Henry questions if I have full power… I have!
As I relax the back pressure on the control column the tail comes up on its own, the elevator becoming effective at about 25kt. I hold it level and once all three wheels are clear of the ground, let the aircraft accelerate. Single engine safety speed is 67kt and acceleration is slow. With the boundary trees getting closer I gently ease back and ? once clear ? lower the nose to get a climb speed of 80kt.
As we get airborne I find the aircraft yawing and try to correct, but manage to get into a pilot-induced oscillation, weaving the nose left and right, much to Henry’s annoyance (quite understandably). I’m not sure why; it may be lack of talent on my part, or I haven’t adapted to the lightness of the aerodynamically balanced rudder. A small input is required, wait for the result, and then gently adjust.
I finally get my act together and we cruise along at 1,500 feet and 95kt. The rudder feel is different, although effective once you get used to it, and the elevator is light and responsive. However, as Henry says, “It’s interesting to see how they made four ailerons do so little!”
After some gentle general handling it’s time to return to Rencomb. The view is very good ? although, with all the clear panels, I can imagine operating in a hot climate would have meant improvising some sun shading. Once established on final at an initial approach speed of 75kt, the approach angle looks steeper than it is. Don’t forget there are no systems to worry about, so the only landing checks are making sure fuel is sufficient for a go-around and the tail wheel is locked.
We are landing slightly uphill and Henry advises 65 knots over the hedge and to be prepared for a large control column movement to complete the flare. The aircraft is very stable and all goes well, touch down is satisfactory and we track straight for a run of about 400 metres. I unlock the tailwheel and we return to the hangar.
Shut down is standard Gipsy Major: idle for a minute to allow temperatures to stabilise, then mags off and at the same time open the throttle, once the engine stops, mixture lean. The throttle is opened to minimise the tendency of the engine to backfire or run on, which can damage the cylinder heads and magneto drive gears.
Comparing the Dragon to a modern machine is probably not entirely fair as they are very different and it takes time to get comfortable with any aircraft flown for the first time. In its day the Dragon was quite rightly a success, capable of carrying a maximum of eight people over short sectors ? all that was needed then ? on about sixty litres per hour. I think flying on instruments for any great time would have been very tiring especially in rough weather, but otherwise it’s a great machine.
BETTER GET UP AND GO
The Lear 45, as you would imagine, has slightly better get up and go: unrestricted by ATC and passenger comfort, a 4,000fpm-plus rate of climb after takeoff is possible, and an average of 1,600fpm up to FL430 is normal.
Pre-start checks complete, starting is all automatic; just press the relevant button on the central pedestal and the digital electronic engine control looks after the rest. If there are any problems, just move the thrust lever to cut off. The after-start and taxi checks are more complex than the Dragon’s; flaps, spoilers, reverser and various other systems being assessed.
As with all jets, takeoff speeds vary dependant on weight, airfield elevation and air temperature, but at mid weight, sea level and 10°C the 45 will be have a take-off decision speed of 105kt, a rotation speed of 110kt and a takeoff safety speed of 118kt, with a distance of about 1,200 meters. The only figures I found for the Dragon gave a flight test performance of passing 120ft after a run of 550 yards.
Taxying the 45 requires practice; the steering is with the rudder pedals and is digital so there is no feel. Press the rudder pedal and a computer sends a signal to an actuator to move the nosewheel.
With the thrust levers pushed to the takeoff detent on the pedestal, acceleration is rapid with a healthy shove in the back, rotation speed approaches rapidly and the after takeoff period can be busy with gear and flap retraction, noise abatement procedures etc. The controls are firm, but not overly heavy and hand-flying is a pleasure. Being an entry-level jet it doesn’t have autoland or auto throttle but it is still very capable.
The approach and landing take more planning than the Dragon’s: checks need to be completed and speeds calculated, navigation aids set etc. Average weight speed on the approach is about 130kt to a touch down reference speed of about 120kt depending again on conditions, landing distance is around 700 meters.
With the firm but well balanced controls, the approach is easy to fly and if an orbit or visual approach is required the aircraft can be hand-flown easily and accurately. The trailing link undercarriage gives a smooth ride on touchdown, and reversers and carbon brakes make short landing distances possible.
You may wonder why I haven’t mentioned single-engine performance. The answer is they are obviously so different; the Dragon doesn’t have any ? being designed before such things were required ? and the Lear has sufficient!
The difference in designs just sixty years apart is a measure of how far aviation has progressed. Although I probably won’t be around to read it, an article in 2050 comparing the Lear 45 with the latest transport device will be fascinating.