A cockpit is required to contain the driver in safety and comfort, together with any systems to increase that safety and comfort. It must also display all the information he needs in an easy-to-interpret fashion and contain all the controls he will require, arranged for maximum ease of use.
This cockpit design considers the general cockpit features and arrangement, the cockpit displays and controls, the equipment required by the driver and, briefly, the use of a simulator for driver training. With reference to the displays and controls in particular, the reasons for their inclusion and arrangement is dependent upon the function, operation and possible failure modes of the systems; the cockpit design is explained with reference to these factors. A diagram of the main instrument panel layout is attached.
As Thrust SSC progresses the cockpit layout is continually being refined. The current layout is already substantially different to the initial designs and the final configuration is likely to look slightly different again from the layout described below, but the same principles will still apply.
The canopy must give as much forward visibility as possible while protecting the
driver from noise, airflow effects, the effects of a serious accident and the heat of the sun.
Hence it should be strong with an effective airtight seal and it should be acoustically and
thermally insulated. The canopy can be opened both from the inside (to allow the driver
ventilation and rapid egress) and outside (to allow for rescue in the event of an accident).
The likely dynamics of a high-speed accident suggest that an ejection seat would only be of any use if it were so sensitive to violent Car motion that the chances of an accidental ejection would be unacceptably high (and the response time would possibly still be too slow). Hence the seat in Thrust SSC is a fixed moulded seat and offers the best possible support against violent movement. The position of the seat is as far from the instrument panel as functional reach will allow, to reduce the driver’s eye accommodation problems to a minimum. The seat harness is a 6-point design with wide straps to give as much support as possible and the seat is shaped to reduce the possibility of ‘submarining’. Airbags may be of some benefit, but the protection offered by them is unlikely to last for the duration of a typical land speed record accident so they are not being used.
A design similar to that on Thrust 2, using an open-topped roughly oval shape, is suitable. Page Aerospace are currently finishing the manufacture of a bespoke steering wheel for the Car, made to aircraft standards to guarantee reliability of the electrics and to make best use of the cockpit space. Positioning will be towards the far end of functional reach to reduce the chances of contact with the driver in the event of an accident.
The cockpit will have automatic fire detection which will activate the cockpit extinguisher systems automatically in the event of a crash (using inertia crash switches as Thrust 2 did, for example). Fire detection should ideally be obscuration detection (for response to smoke fires), ionisation detection (for response to visible flames) or a combination of both; heat detection does not react quickly enough to be of use. The advantage of twin detection also offers a backup if there are problems with the dust- sensitivity of an obscuration detector. Fire suppression will be by Halon flood and possibly water mist spray as well.
The driver will require an air supply with an endurance of the order of 20-30 minutes and a small positive over-pressure to prevent the inhalation of fire- extinguishing gas; the air bottle and regulator will be positioned well out of the way.
There is no room for a proper air-conditioning unit within the Car so a plug-in external air conditioning will be used in the desert to keep the cockpit cool.
Although a seemingly trivial point, the colour of the cockpit has a significant effect on the appearance and readability of the instruments. A pale neutral colour (light grey is the most common and is preferred for this application) produces a light working environment which improves general internal cockpit visibility and reduces the ‘cluttered’ appearance of the cockpit and instrument panel to a minimum.
The choice of analogue rather than digital instruments is an obvious one given the need to read them in the shortest possible time and possibly using peripheral vision. The only instruments and displays chosen are those which give the driver what he actually needs to know about the status of the systems before and during the run - gauges have not been used to show system status if a simple failure warning light will suffice. All warning lights must be bright enough to ensure they reach or exceed twice the ambient desert light level, in order to be easily visible.
The displays and controls are divided into 2 categories: primary, which the driver needs to use during the runs, and secondary, which are only required before and after the runs.
The positioning of the primary instruments are as close to the driver’s eye-line as possible (without obscuring his view of the front of the Car), and certainly well within the critical 15 degree angle that allows easy monitoring. The primary controls are all hands- and feet-on controls so that the driver can access any of them immediately and (ideally) without having to look.
Secondary controls and instruments should be positioned sufficiently far out of the way to give clear views and access to the primary ones, but should nonetheless be relatively easy to use.
Within these constraints, positioning of controls and instruments for this study is by association: the engine instruments are over the accelerator pedal, the brake pressure gauges are above the brake pedal, etc. All of these features aim to make the cockpit as easy as possible to become familiar with, bearing in mind the very limited experience that the driver will acquire due to the short operating life of the Car.
The controls need to be simple to operate with gloved fingers, logical and positive in function and easy to interpret the position of. For these reasons, all switches are large, locking toggle switches (the convention of up for on is used throughout) and buttons for rapid-operation systems (chute deployment, fire extinguishers) are large, shrouded and positive in operation.
The following list of primary displays is in approximate order of importance (the order cannot be exact as the importance changes with the phases of the run): this order is reflected in the cockpit layout.
Dynamic pressure is the most relevant factor of the Car’s
speed until the transonic region when Mach No. becomes critical. Hence the
primary speed display is airspeed in mph, with a secondary speed gauge reading
Mach No around the transonic range (the limited range of this gauge allows more
accurate reading of speed in the transonic region, where small changes in Mach No.
can have dramatic effects). Both of these instruments have moveable bugs which
can be positioned at the run’s target speed for ease of reference.
The most relevant factor of engine performance is
thrust balance - if both engines are producing the same thrust, they are almost
certainly both functioning correctly. Any engine problems will also become evident
as a fall in thrust before the instruments show an afterburner failure or surge.
Hence the primary engine monitor is a thrust balance gauge (giving the earliest
possible warning of asymmetry), which is a comparison of the output of thrust
monitors on the thrust trunnions of both engines and which is mounted just to the
right of the speed gauges. The Cars’ computers also monitor the thrust balance and
have the ability to initiate an automatic shut-down of both engines if required. As a
backup to the thrust gauge, for setting intermediate power settings and to monitor
general engine performance, a conventional set of engine instruments has been
included, with the nozzle indicators at the top reflecting the fact that the most likely
failure mode of the engines is an afterburner blow-out.
The fire panel, built by Kidde-Graviner, is on the right side of
the cockpit, falling naturally under the dominant hand for a right-handed driver.
The panel contains an extinguisher arming switch, to reduce the chance of an
accidental discharge during maintenance, turn-rounds, etc. The buttons are all lit,
with a fire detection causing the appropriate button on the fire panel to light up.
The appropriate fire warning will light up, together with an audio warning, to
indicate a fire or overheat of that system - pressing any fire button will operate the
correct extinguisher, and in the case of the engines, the left engine extinguisher can
be used to supply a second shot into the right engine bay if required, and vice-versa:
an extremely clever and flexible system. In the case of a cockpit fire detection, the
driver can manually operate an extinguisher or they can be fired automatically in
the event of an accident.
The warning lights are intended to act as an attention-getter for failures of the systems and as such can be positioned further from the driver’s eye-line, only being referred to if they illuminate. The only exceptions to this are the Para Fire, Para Deploy, Abort Arm and PS Loc captions which indicate the status of the systems (e.g. for chute deployment Para Fire indicates the drogue gun has fired and Para Deploy indicates that the chute has properly deployed). The captions are of 2 types: red captions are the most serious and require immediate action; they are accompanied by a high-pitched audio warning. The amber captions are of a less serious nature; they are accompanied by a low-pitched audio warning (these audio warnings are the same as those used in the Tornado F3 fighter). All of the captions also illuminate the STOP light next to the airspeed gauge as a further attention-getter. The captions are grouped together according to their function: the electrical system warning lights are on the electrics panel, etc. As well as making servicing easier - if one of the systems develops a problem, only that part of the instrument panel needs to removed for servicing - it also allows the driver to see at a glance which system has a problem, before he has even had time to read the caption, hence allowing him to react more quickly to the problem.
The primary controls are all hands- and feet-on (with the exception of the fire system as already discussed). The engines are both controlled by the right foot spring-loaded accelerator pedal, which is detented to signify HP cock operation and ‘burner selection. The pedal has a toe loop to cater for a sticking linkage and to allow the pedal to be pulled back to the HP and LP cocks shut position; the toe loop is open-sided on the right to allow the driver’s foot to slide sideways across to a footrest. The brakes are operated by the left foot which rests on an adjacent footrest during the run. The wheel rotation speeds are all monitored: if there is a significant difference between any 2 wheel speeds (indicating the onset of wheel-lock) the W Lock caption will be activated to invite the driver to back off a bit. Finally, the chute buttons are mounted on either side of the steering wheel for easy operation by both hands, while the radio transmit button is at the top of the left side of the wheel.
The secondary displays and controls are only required before and after the run and are generally smaller, less visible and less accessible than the primary ones. Secondary displays and controls are:
The electrical system is located on the left side of the main instrument panel. Two gauges indicate main and emergency battery voltages; the panel also contains the battery master switches and computer switches.
The engine start switches are mounted off the instrument panel, with the auxiliary hand throttles which are used for engine starting and test- running.
The radio is also mounted off the instrument panel: once the volume has been adjusted no further access is likely to be required.
The fuel tank contents gauges intended to give a confidence check of the fuel contents before the start of the run.
The clock contains a stop watch and is both to allow the driver to back up the timing and to stop him becoming time-disorientated during any delays.
The hydraulic gauges are used to monitor the performance of both the electric- and engine-driven hydraulic pumps, and to check the pressure in the brake lines before the run.
The driver equipment will be similar to that used in Thrust 2. The most important single element of the equipment is the driver’s helmet assembly and the options range from RAF fast-jet equipment to drag-racing and Formula 1 racing designs - these racing helmets undoubtedly offer the greatest crash and fire protection, and can also supply built-in communications systems, but they do not have a long-duration breathing system which is essential for a land speed record attempt. Although not as impact-resistant, the RAF equipment has been designed to survive very high airspeeds, such as would be experienced in a high-speed canopy failure, has high-quality noise reduction and communication systems and, most importantly, a proven breathing system. Fire protection can also be increased to an adequate level by wearing a flame-retarding hood under the helmet and using fire-resistant goggles. For these reasons the helmet choice is an RAF-style flying helmet with its associated oxygen mask assembly. The remainder of the driver’s equipment and clothing should try to combine the (largely incompatible!) aims of fire protection and the avoidance of heat stress, and is likely to be racing-style equipment.
The cockpit’s complexity reflects the greatly increased complexity involved in building the
world’s first supersonic car. To familiarise the driver with both the performance of the
vehicle and all of the displays and controls available to him, something more than a few
practice runs at low speed on a runway are going to be required. For this reason, the Thrust
team approached the Defence Research Agency (DRA) to ask for their help in building a
high-fidelity simulator, which would also allow the team to carry out some additional
research into the performance characteristics of the Car. The DRA produced a simulator in
4 weeks - this kind of job would normally take 4 to 6 months - and loaned it to the SSC
stand at the Earls Court Motorshow in October ‘95, where it ran faultlessly for the whole of
the show, letting the public experience what it is like to go supersonic on land.
The simulator training is not intended to replace actually driving the Car but to make the environment less alien, and has already proved extremely valuable in preparing Andy Green for his first drive in early ‘96. The cockpit design has been extensively tested in the simulator and further changes will be incorporated to let Andy try them out before the cockpit is even finished. In particular, familiarisation with the very high speeds and rates of acceleration is something that cannot be achieved by any other means - Thrust SSC is the most powerful land speed vehicle ever built and, while it is likely to be an extremely demanding vehicle to drive, the simulator allows the team to better-prepared for the event than any team in history.
Andy Green, December 1995
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