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Old 31st Aug 2010, 17:04
  #170 (permalink)  
M2dude
 
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DozyWannabe
Well, it was essentially a development airframe pressed into premature service for the sake of beating a western project into the air. One wonders whether the story would have been different if the designers had been allowed to take their time and develop it properly.
Good point I suppose, but you could say that the six Concorde prototypes, Pre-Production and Production Series Test aircraft were also development aircraft, and yet more or less worked just as it said on the tin', where the TU144, in spite of all the facilities of Andrei Tupolev's design bureaux, not to mention more or less unlimited Soviet state funds produced a machine that in my opinion really BELONGED in a tin can. (I know this is all off topic, honest guys, I won't mention this stuff again ).
In reality the Soviets really lacked both propulsion technology as well as the systems expertise required to build an aircraft with even a remote hope of Mach 2 cruise, let alone safe and comfortable enough for fare paying passengers. The original aircraft had all for engines in one giant nacelle, and the landing gear retracted into the engine inlet duct itself, great for an undistorted flow path to the engines . The variable inlets were manually operated by the flight engineer as well, no automatics here. In the mid 1970's the Russians even approached PLESSEY to build a digital engine control unit for the TU144. A similar PLESSEY unit had been VERY successfully flight trialled on production series aircraft 202 (G-BBDG) and only lack of funds prevented it being used on the production aircraft. As this unit could obviously be used for Soviet military applications, there was objection from the UK government, and more than just a little trans-Atlantic pressure applied, and so this venture never happened.
Those "agricultural" fighters can mix it up with the best the west has to offer (until - or if - the F22 comes online) in terms of manoeuvering ability, if not in terms of weapons.
Until the advent of the Mig-29 and Sukhoi SU-27 this really was not the case. I'm afraid I'm with galaxy flyer on this; If you look at the air war over Vietnam, when an F4 met a MIG 19 or MIG 21 in an even air-to-air combat, the MIG was going down. (OK this could be partially down to superior US pilot traing etc, but if you look at the handful of skirmishes where the 1960's/1970's Soviet aircraft were engaged in Combat against US or French built fighters, the MIGs never really did very well at all). However, the aircraft that the Russians have been producing from the Mig 29 onwards seem to be in a completely different class now; hope they really are the good guys now.
ANYWAY, back on topic
Lurking SLF
No problem at all Darragh, please keep visiting us and post here also anytime.
Nick Thomas
M2dude I have another question concerning "debow" You very clearly answered my original question on another thread. I just wondered how the engine was kept at a sub idle 30% N2? Was it done by careful metering of the fuel? and if not how was it done? I ask because the throttles would be closed during start up.
I'm not sure that I can describe the DEBOW process remotely as eloquently as my friend Bellerophon did, I particularly loved the 'out of balance tumble-drier' bit, but starting a hot or even warm engine, even at DEBOW, you could certainly 'feel' the noise on the flight deck, until the shaft distortions evened out.
Now for the PFM bit, equally eloquently alluded to by Bellerophon:
DEBOW itself was maintained by a special sub-idle datum in the electronic Engine Control Unit, and once the engine was accelerated towards normal idle (61-65% N2, depending on the temperature of the day) even if the switch described by Bellerophon was accidently re-selected, an electronic inhibit gate in the ECU prevented this sub-idle datum from being used again that engine cycle.
Thanks for the explanation of how the pitch was "trimmed" Due to Concorde having elevrons instead of ailerons; was the aileron trim dealt with in a similar way? I guess the rudder trim could be applied normally.
You're welcome Nick, actually the roll and yaw trims operated in a similar manner to the pitch, although of course these was applied by a manual trim wheel only. (No French bike bell either ). Rotation of either wheel (more a giant knob actually) merely shifted the neutral datum of the relevant artificial feel unit, which in turn shifted the rudder pedals or control yoke; the resolvers for the FBW system would in consequence demand this 'trimmed' control surface movement.

Dude
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