Page 26 - Aviation News - September 2017

clocked up 20,000 ight Concorde, actively
hours (about half the mitigating the ‘bowing’
design life) but were also of the Olympus main
monitored by a ‘reference shafts was critical, given
ight’ index that factored their ne construction
cycles based upon tolerances for optimum
weight. performance. A function
Additional fatigue of metallurgical diversity,
modelling accounted variable rates of thermal
for the thermal cycles expansion could cause
experienced: initially a slight warping along
cooling at altitude, then the length of the shaft,
heating upon supersonic resulting in vibration
acceleration, reversing and more insidiously,
upon descent and metal fatigue. This effect
deceleration. Kinetic was most apparent
heating restricted the post-shutdown after
maximum speed (nose several hours on the
and leading edge ground, when the effects
temperatures typically of variable cooling
peaked at 130°C and 105°C) but at Mach The variable geometry engine nozzles were most pronounced. To combat this
rotate for use as thrust reversers and, when
2.0, heating was also by solar radiation, airborne, work in combination with the phenomena, engines could be started and
hence a white livery to re ect maximum engine inlets to optimise engine efficiency. latched at a speed below idle, allowing all
heat. With increasing speed, the balance components to equalise: hence the ight
changes, requiring more heat to be of their precise position in response to Mach engineer’s de-bow function. A pre-start
radiated, hence the colour of the SR-71 shockwave onset. motoring sequence for thermal stabilisation
Blackbird. Snecma Moteurs contributed the reheat still occurs on some jet engines, including
and nozzle mechanisms. A variable the CFM LEAP-1A tted to the A320neo.
POWERPLANT geometry nozzle allowed reverse thrust There is no auxiliary power unit (APU)
The term ‘powerplant’ is most appropriate upon landing and was synchronized with as the bulk of the tail contains the tail-wheel
for a unique combination of three elements: the intakes to boost system efficiency. unit and fuel trim tank, impractical in the high
intake system, engine and exhaust nozzles. Reheat was used for take-off and transonic intensity, faster rotations of modern airline
Olympus: even the name for the heart of this acceleration above Mach 1: design elegance operations. For the ight crew Concorde
unholy trinity evokes the crackle of thunder, and the hugely efficient intake system offered a full-regime autopilot and linked
tracing a pedigree from the Avro Vulcan and allowed a sustained supercruise (without autothrottle, permitting a reduced workload
BAC TSR2. Rolls-Royce produced the nal reheat), a feat only matched in the civilian in all phases of ight. This was harnessed
Mk.593 using titanium and nickel-based market by the Tu-144. to a complex air data computer that
superalloys to resist huge temperatures and An unusual problem was detected very automatically monitored parameters and fed
compression ratios. Engines were analogue late on: vibration of engine No.4 caused by them to related systems. Both are key in the
thrust-by-wire, the predecessor of Full the opposing rotations of the wing vortex modern, integrated ight deck.
Authority Digital Engine Control (FADEC) and the engine compressors. The port Aerospace has changed a lot since the
tted even to light aircraft today. engines received a vortex rotating the other 1960s; progress now focuses upon metrics
The intakes are huge, containing ramps way and No.3 was inboard, further from such as economy, turnaround times and
that would extend inwards beyond Mach the leading edge air ow. A modi cation of load factor. Appropriately for the decade
1.0 slowing the incoming air to a speed the inlet vanes and a thrust restriction at low concerned, there are clear parallels with
engines could ingest. As a by-product, this speeds resolved this. On take-off, the reheat President Kennedy’s speech that instigated
also compressed the air ow, boosting the ame of the No.4 engine could initially be Project Apollo – “we choose to go to the
efficiency of the system. In a world rst, seen to glow weaker than the other three: moon…not because it will be easy, but
ramps and their related ducts were digitally the relevant gauge on the ight deck had a because it will be hard”. Never before had the
controlled (computers lifted from BAC guided coloured tab tted as a reminder. giant leaps of a terrestrial aircraft pioneered
weapons systems) due to the critical nature Whilst already understood prior to so many smaller steps along the way.
Here Concorde is rapidly accelerating after take-off. The reheat is not yet
We wish to thank the Runway Visitor Park at switched off for noise abatement, the main undercarriage is retracting and
Manchester Airport and Aeroscopia Musée already telescopically withdrawn. AirTeamImages.com/Philippe Noret
Aéronautique at Toulouse Blagnac Airport for their
assistance in accessing their Concordes to take
some of the images used in this article.

26 Aviation News incorporating Jets September 2017

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