24Hr emergency line +44 (0)20 8476 4099
Join Balpa

Over the moon

by David Mackay Virgin Galactic Chief Pilot

Late 2003. A bar in Hong Kong. After the downturn in the aviation business following the incomprehensible horrors of 9/11, Virgin Atlantic had started phasing out its older 747 fleet, which I’d enjoyed flying since leaving the RAF in 1995. I’d recently converted onto the A340 and was experiencing some new destinations. By coincidence, another Virgin crew was in the same bar and I struck up a conversation with Alex Tai, a fellow VAA captain who I’d got to know in my first days with the company.

Virgin had recently announced that it would sponsor Steve Fossett’s attempt to become the first pilot to fly solo non-stop around the world in an aircraft named GlobalFlyer, which was being built by Scaled Composites in Mojave, California. The aircraft was to be painted in VAA colours, and a small team – including Alex – was formed to oversee our company’s involvement. I’d been a test pilot in the RAF and Alex asked if I would take a look at some documentation received from Scaled.

A few weeks later, Alex and I flew to LA and drove north to Mojave to meet the engineers and test pilots, and to take a look at GlobalFlyer. It was a truly special piece of engineering: its fuel fraction was higher than any other aircraft ever built and, when first weighed, it came out lighter than the original estimates, a rare occurrence in one-off aircraft production. Steve and his GlobalFlyer went on to complete the first solo circumnavigation – without stopping to refuel. But, as a serial record breaker, Steve was not happy with just that; he also wanted to set the ultimate distance record. A few months later, he went around the world again, and then just kept on going. This flight ended with a challenging but successful emergency landing in Bournemouth, UK, with iced-up windows following a generator failure, and he secured another record.

A genius aircraft designer

Scaled Composites is a rapid-prototyping aircraft manufacturer, established and, at that time, still headed by Burt Rutan. Now retired, Burt is a genuine genius aircraft designer, with a very firm grasp of the practicalities of construction and manufacturing, but with a penchant for thinking outside the box. Never content with working just one project, at the time of our visit in early 2004, Burt and Scaled were also flight-testing his most ambitious design, SpaceShipOne (SS1).

A spaceship was something that Burt had been thinking about, and privately working on, for some time. He convinced himself that it could be done by his small company in the desert which, previously, had produced one-of-a-kind machines that mostly operated in the lower-left side of the flight envelope, slow speed – often piston-engine – aircraft. Exceptional though these many designs were, a spaceship was a remarkably ambitious undertaking.

Then came the announcement of the $10 million Ansari X-Prize, to be awarded to the first group that could fly a vehicle, capable of carrying three people into space and back twice within a two-week period. Paul Allen, who co-founded Microsoft with Bill Gates, was one of those inspired by this challenge, and he went to see the one person he thought just might be up for such a challenge – Burt Rutan.

Conveniently, by this time, Burt had matured his spaceship design and was even building and assembling larger components. His plans had coalesced into a winged spaceship, air-launched from a mother ship, with a hybrid rocket-motor configuration – solid rubber fuel and a liquid oxidiser. Like all of Scaled’s vehicles, the mother ship and the spaceship would be built using carbon fibre composite materials.

The crucial re-entry problem was solved by a unique arrangement where the twin tail-booms and horizontal stabilisers, together with a trailing edge flap, pivoted upwards through 60 degrees. This created a powerful nose-up pitching moment, enabling the vehicle to fly at an extremely high angle of attack, creating very high drag during re-entry and slowing the vehicle’s descent. This configuration, known as the feather, was highly stable; no longer any need for the accurate attitude control, which has always been a challenge for vehicles returning from space, this would be a hands-free re-entry.

By the time of the VAA GlobalFlyer team’s visit to Scaled in early 2004, SS1 had already made a few test flights. Although we were primarily there to look at GlobalFlyer, this intriguing little rocket ship was rapidly capturing the world’s imagination, and we were no exception. Talking to its engineers, test pilots and Burt, we had an epiphany: we realised we could be looking at the basis of a commercial spaceship.

Arriving back home after that first visit to Mojave, I excitedly told my wife that Virgin was going into space. She rolled her eyes and quickly brought me back down to earth, telling me to stop being so ridiculous and that the lawn needed cutting.

Nonetheless, a few months later, after Paul Allen had won the X-Prize with Burt’s design, Virgin signed a letter of agreement with Scaled to develop a follow-on larger spaceship and mother ship. When it was decided the early Virgin Galactic (VG) team also needed a test pilot, I was fortunate to be in the right place at the right time.

VSS Unity & VMS Eve prepare for another morning of flying on 1 May 2017. During this test, the feather re-entry system was activated in flight for the first time.

SS2 Enterprise

SpaceShipTwo (SS2) is around twice the size of SS1, scaled up to permit as many as six ‘space flight participants’ to see the black sky of space in daytime, the wonderful views of Earth and its very thin atmosphere, as well as to enjoy the sensation of weightlessness and a Mach 3 rocket ride. SS2 leverages on SS1’s design essentials, building on its proof of concept.

In October 2014, the first SS2 vehicle, Enterprise, was lost in a tragic accident that claimed the life of one of the two Scaled test pilots on board, and brought Scaled’s SS2 flight test programme to an end. However, the SpaceShip Company (TSC) – Virgin Galactic’s sister company – had already made substantial progress building the second SS2 vehicle and, a few months previously, had accepted the mother ship, WhiteKnight2, from Scaled. The long, and very thorough, NTSB accident investigation established that the first SS2 vehicle was a human factors accident. A cockpit control had been moved at the wrong time, but that control was also at fault; the pilot should not have been able to take a single action that resulted in the loss of the vehicle. Essentially, though, the basic spaceship and rocket motor designs were sound and the decision was made to continue the programme.


Human factors

Most of my RAF flying had been in single-seat aircraft, but only rarely did I fly alone. Usually it was as a pair, or a four-ship, and sometimes much larger formations. The majority of the time we flew at high speed and at very low altitude, trying to hit a target within a tight time-window, sometimes being ‘bounced’ by aggressor aircraft. It sounds strange now, but crew resource management (CRM) was something I had barely heard of when I joined VAA. However, in the Cold War era we fully understood the importance of good briefings, standard call-outs and SOPs. The RAF had been practising good communications, standard procedures and teamwork – the basic tenets of CRM – it was just, at that time, we didn’t call it that.

I admit, I had expected to find airline operations to be easier, but it turned out there were many challenges – not least fatigue. Like all airlines, VAA had a standard set of call-outs – challenges and responses – that took me a long time to perfect. But once I had learned my lines, I began to really appreciate the benefits – eliminating ambiguity, increasing efficiency; when used correctly, flight deck operations become easier and, most importantly, safer.

Before the 2014 accident, VG had already started working on improving the SS2 and WhiteKnight2 pilot documentation: the operating handbook, and normal and emergency procedures. After the accident, we pursued this effort with increased vigour and rigour, going through every system on both the spaceship and the mother ship, reviewing our displays, interfaces and procedures. As a result, a large number of changes were made to controls, software, procedures, call-outs and CRM. This effort will be a vital part of ensuring future success.

First powered test flight

Early this year in April, Unity, the second SS2, flew its first powered test flight. This was the longest airborne firing of the rocket motor – also produced by TSC – to date. Such flights are densely packed with test points. The final glide flight prior to first powered flight was launched from 51,000ft, but it only lasted a little over seven minutes in total, and the final four minutes were the approach and landing, without any testing. So, we have very brief windows of opportunity to gather as much information as possible. To achieve this, we spend many weeks fine-tuning the flight test cards, procedures, flight techniques for progressing from one test point to another and, of course, practising our emergency procedures. Our CRM is highly detailed and well-rehearsed.
For every flight we have a large support team – more than 30 people – in Mission Control, watching over our systems, our performance – both vehicle and human – and data in real time. All these people have to be in the loop and abreast of where we are in the test card. Situational awareness is key. When we practise emergency procedures, the entire team has to know how to react and – equally importantly – when not to.

Prior to the first powered test flight, the pilots – together with our doctors – visited the National Aerospace Training and Research (NASTAR) Centre in Philadelphia. There, in a centrifuge, we were able to experience the spaceship’s acceleration profile for a full-duration powered flight. We arranged for tablet computers to be secured in the capsule, with pre-recorded display videos from our simulator at Mojave, time-synchronised with the centrifuge. We practised our callouts, both as pilot flying and pilot non-flying, with the other pilot on intercom in the control room and the same time-synchronised video. This valuable exercise paid off and some small but important changes were incorporated into our procedures and displays.

Flying to space

WhiteKnightTwo, the mother ship, is the first stage of our spaceflight system. It has flown almost 250 times – safely returning to its launch site on every occasion. A similar wingspan to a Boeing 757, it carries SS2 on its centrally mounted pylon, which necessitated a twin fuselage design and four engines. Like SpaceShip, simplicity was a fundamental design philosophy, therefore it has a reversible flight control system – simple cables, rods and bell-cranks connect the stick and rudder to the control surfaces. Thus, control forces can be high and rates of manoeuvre quite low, but, for its role, they are perfectly adequate. There are 52ft between the two fuselages. It’s flown from the right side, meaning the pilots sit 26ft off centreline.

Like many larger aircraft, safe ground operations require close attention – positioning on narrow taxiways has to be monitored carefully. In the air, there is normally no perceivable effect of the offset operating position – it feels like a regular aircraft – but crosswind landings are interesting. We use the wing-down technique. In a right crosswind, touchdown occurs when you expect it, but, of course, the left fuselage is still flying and care has to be taken not to allow it to land with too high a sink rate. In a left crosswind, it can be a little difficult to judge when the first contact – which is a function of the strength of a crosswind – will occur. And that’s only half the task – the right-side landing awaits.

WhiteKnight’s climb performance is remarkable. After take-off, climb deck angles of more than 40 degrees are easily reached at lighter weights. Clean, at altitude, setting idle thrust alone is not enough to descend – speed brakes and/or gear have to be extended. On a spaceflight mission, WhiteKnight drops almost half its mass instantaneously at SpaceShip release. In SpaceShip, release feels like going over the top of a sharply curved roller-coaster rail. Once we’ve confirmed the flight controls are effective, which only takes a second or so, we light the rocket motor. Full thrust comes quickly, but not harshly. The longitudinal acceleration is around 3g, similar to a catapult launch from an aircraft carrier, and it’s constant, for the full duration of the firing, which is more than one minute. Acceleration through Mach 1 occurs in a handful of seconds and is preceded by a gentle bobble in the transonic region. As soon as that is over, we pitch up into the vertical, always accelerating at 3g. The motor is smooth but with just the right amount of noise. A huge amount of energy is released very quickly. The ride really is sensational.

On a full-duration flight, the motor will shut down at around 150,000ft, at which point we are travelling at around Mach 3 vertically upwards, with sufficient energy to coast all the way into space. The sudden reduction in thrust at shutdown momentarily feels like you’re being thrown forwards against the seat harness.

A short duration burn

Our first powered flight in April was a short-duration burn, which peaked at around 84,000ft and just under Mach 2. At that altitude, the view is already extraordinary. Everyone knows that from high altitudes you see the black sky of space in daytime but, still, seeing it with my own eyes for the first time was at once strange and awe-inspiring. My brain associates black skies with darkness on the ground, but the ground on that mid-morning flight was brightly sunlit. We used the feather to recover from apogee. By definition, this may not have been a re-entry, but at those altitudes there is very little air to stabilise or control the vehicle. The feather, however, is a powerful control and, together with the reaction control system, SpaceShip settled into the re-entry attitude. With the resultant extremely high angle of attack, the airflow around the vehicle is turbulent and can cause a little gentle rocking and rolling.

Re-entry ends when the feather is lowered, at around 50,000ft. Now the spaceship becomes a glider; typically, we are within five miles or so of the landing runway at about 35,000ft, so there’s plenty of energy and time to effect a controlled landing. There’s also plenty of performance information displayed in a variety of ways – we are not reliant on a single system or set of data.

The approach glide path angle is around three times as steep as a normal airliner approach and is typically flown at around 160 knots. It flies well and the field of view is good – significantly better than the Shuttle had. We execute a pre-flare at around 400ft, to bring us to a more conventional approach path for the final landing flare. On touchdown, the nose is held off for aerodynamic braking, before lowering at around 90 knots, allowing nose skid retardation to add to main-wheel braking.

In the immediate future, the programme will proceed through small, careful steps towards full-duration powered flights. Our most recent flight in June – another short rocket-burn duration – reached 114,000ft and just under Mach 2. Soon, we will put evaluators in the cabin, before commercial flights start in a few months’ time. The insights we have gained from the flying we have done to date indicate that the customer experience will be truly extraordinary.

Update: On 26th July 2018, Dave Mackay and Mike “Sooch” Masucci flew VSS Unity to 170,800ft and reached Mach 2.47. This was also VSS Unity’s first supersonic re-entry at Mach 1.71.

All featured images supplied by Virgin Galactic.