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Concorde question

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Concorde question

Old 30th Aug 2010, 22:35
  #161 (permalink)  
 
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The original TU144 was an extremely crude attempt by the Soviets at commercial supersonic aviation
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.
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Old 30th Aug 2010, 22:45
  #162 (permalink)  
 
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Having seen some of their other efforts, this one doesn't wonder. Ever fly on an IL96 or see a IL62? Their fighters aren't crude, they are positively agricultural! Out tractors are more elegant in their engineering.

GF
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Old 30th Aug 2010, 22:56
  #163 (permalink)  
 
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The TU144D used in the 1990's as a joint NASA/Russian experiment was a different beast altogether however, with far better engines and systems, but as far as I am aware the only western pilots to fly it were American chaps
I wasn't aware of the significant upgrades - devised into the tune of $300mn - that where applied to this airframe. Your remarks made me read some very interesting articles on this project.
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Old 30th Aug 2010, 23:01
  #164 (permalink)  
 
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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.
The whole engine installation with the ramps, spill doors, reheats and noozles must have been a nightmare to "fine tune" through all the different phases of flight.
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.
Thanks again
Nick
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Old 31st Aug 2010, 00:22
  #165 (permalink)  
 
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Originally Posted by galaxy flyer
Having seen some of their other efforts, this one doesn't wonder. Ever fly on an IL96 or see a IL62? Their fighters aren't crude, they are positively agricultural!
This is off-topic, so I ain't going to bang on this subject after this post, but I wouldn't be so quick to denigrate former Soviet technology in all cases. 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. Elements of their rocket technology were in advance of what we had at the time, and the solutions they came up with to put the Tu-144 in the air may have been crude, but they were to some degree effective, which can denote an elegant solution in itself.

That said, this thread is about an aircraft which was the result of - unarguably - some of the best engineering in aviation history, and I'd much rather talk about that!
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Old 31st Aug 2010, 00:25
  #166 (permalink)  
 
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Nick Thomas

...I just wondered how the engine was kept at a sub idle 30% N2?...

Just below each engine's individual start switch, there was a second switch, which would select the type of start required, either NORMAL or DEBOW.

When between ten minutes and five hours had elapsed since an engine was last run, a debow start was required. With a debow start selected, the engine was started normally, but the debow system automatically stabilised the engine at a sub-idle RPM, around 30% N2, whilst the interior engine temperatures became more uniform and the HP spool shaft re-aligned/straightened itself.

As to exactly how it did this, you're going to need a reply from an engineer not a pilot. As far as we were concerned, it was the PFM box in the engine start system!

After running for one minute stabilised in debow (or when the debow light came on) the F/E would return the debow switch to normal and check that the N2 returned to idle and the debow light went out. The F/E would monitor the N2 very carefully over these few seconds, as the engine came out of debow, to check that the engine cleared rotating stall.

If it didn't, two things would happen.

Firstly the F/E got fairly busy, trying to clear the engine out of rotating stall without causing it to surge, and secondly, as with any Concorde engine malfunction drill, I quietly give thanks that I was a pilot and not a F/E.

If a debow start was required, but somehow got missed, the engine could give a reasonable impression of an out-of-balance tumble drier, or so I'm told.

Best Regards

Bellerophon
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Old 31st Aug 2010, 02:18
  #167 (permalink)  
 
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DW

No argument from me on former Soviet fighters being capable, but please read Red Eagles, if you want a Western view on their planes. Lots of poor engineering and execution, not that impressive.

GF
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Old 31st Aug 2010, 07:44
  #168 (permalink)  
 
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M2Dude,

Sorry, I certainly don't consider it a wasted two hours - I should be more careful in my phrasing in future...

I never got to fly on Concorde, but I did get to sit in the left hand seat in Manchester for a few minutes on one of their tours - it's one of my prouder pictures on my desk.

Apologies for not getting the tone I wanted across - and no offence taken!

No more post from me in this forum - I'll leave it to the experts...

Lurking_SLF

Last edited by Lurking_SLF; 31st Aug 2010 at 08:46.
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Old 31st Aug 2010, 12:54
  #169 (permalink)  
 
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Originally Posted by M2dude
The TU144D used in the 1990's as a joint NASA/Russian experiment was a different beast altogether however, with far better engines and systems, but as far as I am aware the only western pilots to fly it were American chaps.
Originally Posted by atakacs View Post
I wasn't aware of the significant upgrades - devised to the tune of $300mn - that were applied to this airframe.
To conclude this slightly o/t story :

The Tu144D was the last production model of the Tu144.
With improved engines and other refinements, it was capable of supercruise (Mach 2 without afterburners). Only five were built, and they came too late ; the aircraft went out of service, and were put into storage.

Tu-144D s/n 77114 was brought out of mothballs (with less than 83 hours "on the clock") for the joint NASA/Russian program in the '90s and modified, with completely new more powerful engines (same as those of the 'Blackjack' Tu-160 bomber) and a fit of sensors and test equipment, to become the Tu-144LL (flying laboratory). A total of 27 flights were made.

The entire "High Speed Civil Transport" study indeed cost over $300M, but the actual work on the Tu-144LL reputedly cost less than $20M, although it's not known exactly what that bill represents.

CJ
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Old 31st Aug 2010, 17:04
  #170 (permalink)  
 
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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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Old 31st Aug 2010, 20:26
  #171 (permalink)  
 
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The BR710 on the GLEX and G 550 also need to "rotor bow" on start within the same time limits. I fly the GLEX and the FADEC does it automatically, but I understand the G550 installation requires the pilots to recognize the requirement and motor for 30 seconds. Sub-idle vibration is quite discernible during an unbow start. Interesting that RR engines require this as I have flown GE and P&W, never heard of it.

GF
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Old 31st Aug 2010, 20:44
  #172 (permalink)  
 
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Originally Posted by DozyWannabe
Well, it was essentially a development airframe pressed into premature service for the sake of beating a western project into the air.
Originally Posted by M2dude View Post
Good point I suppose, but you could say that the six Concorde prototypes, Pre-Production and Production Series Test aircraft were also development aircraft
Something I think I hinted at before, was how much the two Concorde prototypes differed from the aircraft that followed, even from the pre-production aircraft.

Wherever you look... the cockpit, the visor, the engines, the tail, the avionics, other systems... the prototypes were a first "iteration", designed and built to prove the concept.

The real development was done on what were the real "development aircraft", the pre-production and first two production aircraft (even if 01 / G-AXDN was a bit of a hybrid, retaining the short tail and the early engine nozzles).

I hope sometime the story; of how different were 001 and 002 from those that followed, will go on record before it fades into the mists of time.

CJ
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Old 31st Aug 2010, 21:19
  #173 (permalink)  
 
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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
Umm, at the risk of thread drift and also offending those who were there dare I say that's a little broadbrush. The USAF had serious issues early on in the Vietnam conflict with the exchange rate (of losses), due in part to the dreaded Rules of Engagement but also due to the F4's poor turning performance vs. the Mig 19/21, exacerbated by the average USAF pilot's lack of training in Dissimilar Air Combat.

Certainly in F-4 v a Mig 19/21 (especially the later varient 21's) with a determined pilot I wouldn't be as bold as to assume "the "MIG" was going down" - ask anyone who's done any training with the Aggressor Squadrons

Last edited by wiggy; 31st Aug 2010 at 22:05.
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Old 31st Aug 2010, 22:25
  #174 (permalink)  
 
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Originally Posted by wiggy View Post
Umm, at the risk of thread drift ....
Yes indeed.
That sort of discussion belongs in the Military Aircrew forum.

One could say that the Tu-144, and also the Boeing 2707 and Lockheed L2000 were part of the background against which Concorde was born.

But "F-4 v a Mig 19/21" is not really part of that context...... so please?

CJ
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Old 31st Aug 2010, 22:41
  #175 (permalink)  
 
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CJ

Back to thread, which came first, the American designs or the Concorde? Somehow I thought the American entries were a reaction to the Concorde. In any case, both US planes would have been huge. There has been talk of a supersonic biz jet for decades, but no real progress and I doubt there will be until it can fly over land supersonic.

GF
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Old 31st Aug 2010, 23:00
  #176 (permalink)  
 
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Originally Posted by galaxy flyer View Post
CJ
Back to thread, which came first, the American designs or the Concorde? Somehow I thought the American entries were a reaction to the Concorde.
I think you're right, but I'd have to look up some dates first.

Interestingly, all the supersonic transport designs of the era (Concorde,Tu-144, B2707, L2000) can trace their ancestry back to NASA (NACA?) public-domain studies of the late fifties, that demonstrated the advantages of a slender delta for a supersonic transport aircraft.

CJ
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Old 31st Aug 2010, 23:19
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Hi everyone
Please correct me if am wrong but was there not a slender delta wing prototype built by Fairley in the middle fifties. As I understand it, the plane was built to study a delta wing performance at low speeds. Therefore it had a fixed undercarriage.
Regards
Nick
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Old 31st Aug 2010, 23:57
  #178 (permalink)  
 
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But "F-4 v a Mig 19/21" is not really part of that context...... so please?
Forgive me for butting in again, you're in part quoting me but I wasn't the one that brought the F-4 into the debate in the first place. If the Concorde fanclub brings the F-4 vs MIG 19 into the debate and then glibly uses it as an example of the superiority of Western technology then I feel there's a right of reply from those of us who have actually flown the aircraft ( 1000 hours F-4 in my case) and used the technology, irrespective of wether or not it's a military or civil forum....or do you just want to argue in the abstract?

As a general point many in the West have almost always believed in the superiority of Western designers and engineers and whilst Concorde may be one shining example of what the West did right we should not forget that on the evidence of Sputnik, Vostok, Luna 9, Lunakhod and even the MIG21 Russian ( or German ) engineers can achieve worldbeating results with minimal resources.

But, to summarise, yes, it would seem the TU-144 was a dog , does that get us back on thread?

Last edited by wiggy; 1st Sep 2010 at 00:54.
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Old 1st Sep 2010, 03:56
  #179 (permalink)  
 
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Nick Thomas
Please correct me if am wrong but was there not a slender delta wing prototype built by Fairley in the middle fifties. As I understand it, the plane was built to study a delta wing performance at low speeds. Therefore it had a fixed undercarriage.
I think you are refering to the Handley Page HP115 Nick. The Fairey design was the FD2, the first conventional aicraft in the world to exceed 1,000 MPH in level flight. A re-winged version, designted the BAC 221, was used also to evaluate the handling characteristics of an ogival delta wing for the Concorde pragramme.

Dude
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Old 1st Sep 2010, 07:16
  #180 (permalink)  
 
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Thanks M2dude. You are right and my memory is getting worse due to old age!
Regards
Nick
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