|Engine Model||Olympus 593 Mrk610 turbojet|
|Maximum thrust produced at take off, per engine||38,050 lbs (170 KN) (with afterburner reheat in operation)|
|Maximum thrust produced during supersonic cruse, per engine||10,000 lbs|
|Reheat contribution to performance||20% at full thurust during take-off|
|Fuel Type||A1 Jet fuel|
|Fuel Capacity||26,400 gallons /119,500 ltrs / 95,680 kgs|
|Fuel Consumption (at Idle Power)||1100 kgs/hr (302 Gallons/hr)|
|Fuel Consumption (at Full Power)||10500 kgs/hr (2885 Gallons/hr)|
|Fuel Consumption (at Full Re-heated power)||22500 kgs/hr (6180 Gallons/hr)|
|Typical miles to the gallon per passenger||17 Miles!|
|No of Production versions supplied to airlines||67 (63 remain in use)|
The Rolls-Royce/Snecma Olympus engines that are fitted to Concorde are a highly developed version of the Bristol-Siddeley Olympus that was fitted to the Vulcan bomber, which generated 11,000Lbs of thrust. Roll-Royce provided the development of the Olympus engines while SNECMA developed the exhaust and reheat system. On the prototypes this powerplant system was upgraded to generate 33,000Lbs of thrust and by the time it was fitted to the production aircraft, 38,050Lbs were available.
To protect the later compression stages the last 4 stages are constructed of a nickel-bassed alloy, the nickel alloy is usually reserved only for the turbine area. The speed or RPM of the engine's outer shaft is controlled by the amount of fuel being burnt. By varying the surface area of the primary nozzel, the inner shaft RPM on the inner shaft can be controlled relative to the outer shaft RMP
Concorde is the only civil airliner in service with a 'military style' afterburner system installed to produce more power at key stages of the flight. The reheat system, as it is officially known, injects fuel into the exhaust, and provides 6,000Lb of the total available thrust per engine at take off. This hotter faster exhaust that is used on take off and is what is mainly responsible for the additional noise that Concorde makes. The reheats are turned off shortly after take off when Concorde reaches the noise abatement area.
The reheats are turned back on, by the piano switches behind the thrust leavers, for around 10 minutes once the aircraft is clear of land, to push the aircraft through Mach1 and on to Mach1.7 where they are no longer required.
The Aircraft has an electrically controlled throttle system that is used to control the power delivered from the engines. Moving the throttle leavers asks the computer to apply the power to the engines in a correct and controlled manner. Through throttle master controls on the overhead panel, each engine can be either connected to the throttle lever (main) to an alternate controller or not controlled at all.
The engines also have ratings where they can be selected to different power or rating settings for different parts of the flight. eg take off or cruise. A contingency setting is available for use during engine failure and more power that normal is required from the remaining engines
There are two auto-throttles systems fitted to the aircraft that are associated with the autopilot systems. Each engine can be manually disconnected from the auto-throttle system if required. The Autopilot and auto throttle system will be described in another section of the site.
The pictures above show a Rolls-Royce Olympus Engine displayed during the 2000 Farnborough Air Show, only days after the Paris Concorde crash. Looking on from the rear in the last photo, the afterburner (reheat) system can be clearly seen, it is the smaller ring structure situated inside the engine casing
At Rolls-Royce in the 1970's, a new engine is being prepared for shipping to the Concorde production line in Bristol
To further improve engine system performance, the air flow through the engine area is changed at different speeds via a variable geometry intake control system. Altering this airflow changes the amount of air available to the engine and the amount of air that in itself is producing thrust via the complex ramp and nozzle assemblies.
The air intake ramp assemblies main job is to slow down the air being received at the engine face to subsonic speeds before it then enters the engines. At supersonic speeds the engine would be unstable if the air being feed to it was also at a supersonic speed so it is slowed down before it gets there.
At take off the engines need maximum airflow, therefore the ramps are fully retracted and the auxiliary inlet vane is wide open. This vane is held open aerodynamically. The auxiliary inlet begins to close as the Mach number builds and it completely closed by the time the aircraft reaches Mach 0.93.
Shortly after take off the aircraft enters the noise abatement procedure where the re-heats are turned off and the power is reduced. The secondarry nozzles are opened further to allow more air to enter, therefore quietening down the exhaust. The Secondary air doors also open at this stage to allow air to by pass the engine.
At slow speeds all the air into the engine is primary airflow and the secondary air doors are kept closed. Keeping them closed also prevents the engine ingesting any of its own exhaust gas. At around Mach 0.55 the Secondary exhaust buckets begin to open as a function of Mach number to be fully open when the aircraft is at M1.1
The ramps begin move into position at mach 1.3 which shock wave start to form on the intakes.
At take off and during subsonic flight, 82% of the thrust is developed by the engine alone with 6% from the nozzles and 21% from the intakes
At the supersonic cruse speed of mach 2.0 the ramps have moved over half their amount of available travel, slowing down the air by producing a supersonic shockwave (yellow lines) at the engine intake lip.
When the throttles are brought back to start the decent the spill door is opened to dump out excess air that is no longer needed by the engine, this allows the ramp to go down to their maximum level of travel. As the speed is lowered the spill doors are closed and the ramps begin to move back so by M1.3 are again fully retracted.
The ramps can continue in operation till Mach 0.7, should an engine have had to have been shut down.
During the Supersonic cruse only 8% of the power is derived by the engine with the other 29% being from Nozzles and an impressive 63% from the intakes.
Should an engine fail and need to be shut down during supersonic cruise, the ramps move fully down and the spill door opens to dump out exess air that is no longer required by the failed engine. The procedure lessens the chances of surges on the engine.
After touch down the engines move to reverse power mode. The main effect of this is that the secondarry nozzle buckets move to the closed position directing airflow forwards to slow the aircraft down.
The dual air intakes ramps are controlled by 8 Air Intake Control Units (AICU), 2 for each engine intake - Lane A and Lane B. The AICU's are the brains of the whole system, and a great deal the development work on the Concorde design was taken up in perfecting this very important system, that makes supersonic cruise both achievable and affordable by constantly changing the positions of the ramps in respect to changes in airflow, air temperature, engine power and aircraft incidence. 7 out of the 8 control units need to be in working order otherwise supersonic flight can't continue.
Data such as true and indicated pressure along with the aircrafts level of incidence are feed to the AICU's via the Air intake sensor units. The sensor units essentially take the data from the relevant sensors on the aircraft such as the staic and Pitot sensors in analogue form and convert them to a digital data stream that can be processed by the AICU's. Sensors also feed directly to the AICU's the pressure and current positions of the ramps so that they can alter them as conditions dictate. It all seems very simply in today's digital world but for the 1970's the system was way ahead of its time..
The flight engineer has 2 main panels that allow him to monitor both the status of the air intake processing and also the actual positions of the ramps. Click the panels for a larger version in a new window
The Air Intake Management Panel shows what lanes are being used to control the intakes, what hydraulic system is being used along with providing other feed back for any errors that may occur on the sensing or control systems. The guarded switches at the bottom allow control to be given to the inching switches on the Manual Control Panel. The Vane indicator shows the position of the Intake Aux Inlets. Either open, closed or in-travel as shown by the cross hatch in this picture.
The 2nd panel, the Manual control panel, provides feedback of the positions of both the ramps and spill doors that are on the individual intakes. Additionally it provides direct manual control of the ramp positions should the Control units fail.
Former Concorde Test Pilot Peter Baker has supplied me with the following detailed schemaitc block diagram of the final intake control systems that were fitted to the production standard Concordes and how they are controlled.
Click on the picture to see it full size in a new window.
Although the same as all the other 3 engines, the starboard outer engine needs to be treated in a different manner at slow airspeeds compared to the other 3. In fact the procedures related to what is done were not fully developed until Concorde was just going into passenger service in January 1976.
The main issue is that at slow airspeeds the engine suffers vibrations on the low pressure compressor blades from air vortices, that are created by the wing leading edge sections, entering it from both the air intake and fully open AUX inlet door that moving in an anti-clockwise direction, which is the opposite direction to the engine's direction of rotation. The effect is not seen on engine No1, as the vortices travel in the same direction as the aircraft.
2 solutions were adopted to smooth the airflow reaching the engine:
For air entering via the AUX inlet vane a remedy was found that to limited the opening of this vane by about 4 degrees, compared to the other 3 engines, reduced the buffeting to a tolerable level.
If you stand underneath or behind Concorde during take off (with your Fingers in your ears!) look and it can be clearly seen that the no4 AUX inlet vane is not as open as the other three. The reheat flame on engine 4 is also not as bright or stable as the other three during the initial take off roll, until the aircraft is around 60knts when it matches the others.