Posts about: "Intakes" [Posts: 171 Page: 9 of 9]¶

@a-q


Ah yes, page 55 from 4 years ago ...... It's my age you know!


What threw me was your reference to a leaky intake - on 101 it was all the nacelle aft of the intake that leaked not the intake itself

At low altitude think 455 ktCAS.
Tmo was a long exposure structural limit
Mmo was an intake limit
Vmo was a structural (flutter) limit

Bit of a hypothetical question requiring a judgemental response!
My short answer would be not much more than the certified limits - at least not without significant modifications.
FL680 was achieved at the end of a zoom climb, so the Mach No was a lot less than 2.0
M2.23 was in a shallow dive. The object was to demonstrate sufficient margin to avoid surge following the worst temperature transient specified in the TSS regulations. To that end both the intake laws and engine operating lines were tweaked as functions of Mach No to minimise intake flow distortions and maximise surge margin. The result was a long way from the performance optimum one would need for steady cruise.
The power plant was being pushed to its limits at this Mach No.
(As an aside, the subsonic rules make no mention of temperature transients as a cause of Mach exceedences. Some recent incidents suggest this could usefully be reviewed)
The altitude limit could perhaps be more readily expamded. The aircraft normally flew a cruise climb bcause at Concorde cruising altitudes there was no ATC conflict. The altitude was very sensitive to ambient temperature and aircraft weight. FL600 would be associated with end of cruise on a coolish day.
To usefully increase cruise altitude would require more engine thrust, but this could only be obtained by increasing engine TET which would screw the engine fatigue life.
Increasing Mmo from 2.04 would need an increase in Tmo (400 deg K) at any temperature above (from memory) ISA. This in turn would affect the airframe fatigue life unless the structural material were changed. Even then, there were a lot of nonmetallic bits (seals etc) that would also have needed replacement.
Sorry if this is a gloomy assessment, but that is the way I see it!

According to this, 5500-6000 feet/1700 meters

Heritage Concorde

IIRC from one of the previous posts here, the strong differential required also defined the normal descent/deceleration timing and distance.

Power could only be reduced to 94% (N1 or N2, I forget which) or there would not be enough "bleed" air available to maintain the cabin altitude at TOD.
(although I could have misinterpreted that - it may have had more to do with maintaining the oblique inlet shocks, or hydraulics, or some such.)

Tanks 5 and 7 inlet valves have an \x91override\x92 position, do they not?

During the t/o roll, while the trim transfer pumps in 11 will be off, the de-air pump would allow flow through the trim transfer pipes to any tank with an open valve. The valves *should* be closed, unless someone had been creative with any override selections and failed to return them to normal.

I\x92m not sure we *know* the tank 11 txfr pumps were on.

The 5/7 inlet valves were in the override position.

Even if the T11 txfr pumps were off, the de-air pump would pump fuel to the trim txfr pipes and hence to 5/7.

All assuming I remember the report correctly.

The nub being, if you \x91hide\x92 fuel and forget to return the 5/7 inlet valves to normal, you will still feed 5/7 even if the 11 pumps are off.

hi! I know I may be super late to the party here, wondering if you have another picture of that fuel vent schematic? I can\x92t seem to see that one, maybe it\x92s been too long. Anyway it\x92d be much appreciated. Thank you!

Thanks for the reply, Concorde expertise is always interesting. I should not have called the F-16 Emergency Power Unit a RAT, it is indeed not. The Concorde RAT was located aft between the engine pods, correct?

What I found interesting is that the AC generators would remain on-line at all; they drop instantaneously at subsonic speeds and the associated N2 rpm. I believe the hydraulics on the 747 will power flight controls down to a pretty low IAS.

Four engine flameout is a very unlikely event, unless one runs into a volcanic cloud.

There are folks here who can correct me, but in the meantime, what I think I know is....

The DC-Dallas route, entirely over populated land, could not be flown at supersonic speeds (regulations, noise pollution, sonic booms), but Concorde could do it in high- sub sonic cruise at around Mach 0.95, somewhat faster than the norm for regular subsonic transports.

I believe the DC-MIA route was flown mostly supersonically, by climbing subsonically at Mach 0.95 straight down the Potomac to the Atlantic at Norfolk, Va., and then, 20+ miles offshore, turning SW towards Miami and making the supersonic acceleration-climb out over the water. Remained offshore (dodging the coastal bulge of the Outer Banks) until about 250nm from Miami. where the descent/deceleration phase would slow it to subsonic speed before getting too close to the shoreline.

Once at ~28,000 feet at Mach .95 - and over the water - it only took a few moments, after turning on the reheat/afterburners, to punch through Mach 1, and maybe 20 minutes (depending on weight) to reach 51000 feet* and Mach 2.02 (air termperature permitting.) And maybe 20 minutes for the deceleration/descent to Mach 0.95 at ~34000 feet.

(*I believe the afterburners were switched off at Mach 1.7 - usually about 42000 feet? - at which point the dry thrust of the engines and fancy shockwave-pressurized nacelle design could maintain the IAS and (reduced rate) climb (and increase the Mach) all by themselves.)

Across the Pond, short "experience flights" from both Paris and London were made from time to time - get out over the Atlantic, light up the afterburners, and tool around at supersonic speeds for some part of an hour before returning to base.

I'm pretty sure subsonic flight was never really efficient at any speed. Concorde was dependent on Mach 1.7 or so (and high altitudes) to maintain the efficiency of nacelle thrust modulated by supersonic intake shockwaves, without very thirsty afterburners. I think that over the Atlantic, losing just one engine (25% of thrust) was enough to make it instantly a fuel emergency situation - you were going to come down into thicker air and fuel burn would skyrocket.

Someone I used to know,(TO), was a F/O on a Concorde that had a double engine failure mid Atlantic. One engine surged and coughed an inlet door out of the front and it went down the adjacent engine, The vibration was very high and both engines were shut down. The Mayday call to Shanwick was that they may not make Shannon. The reply was that they would alert the coastguard.
IIRC they restarted the engine with the lowest vibration and made it to Shannon.
I saw some photos of the engine that ate the door and the compressor was a mess.

Hi, for some strange reason I have only just come across this thread, I have looked at some of the early posts and can answer a few questions.
I was a development engineer on the AICU in 1972 and put the first AICU together and got it working.
I am now a volunteer at Aerospace Bristol and we have this box in the archives, it was used on the intake rig by Roger Taplin, half way down the hill at Filton,
There are no secret components used in the AICU, TTL 54 series was used, and these are the milspec version of the 74 series TTL. they are better quality, reliability and better tolerance, and more expesive. They were not available to all countries.
I worked with Ted Talbot at the time and in 1990 he recruited me to be the design manager for aircraft conversions and my first job was to manage the design of the VC10 tankers. There was mention of the leggy girl at Tangiers, that was Liz Pedley, a Cambridge maths graduate systems engineer, she married a GW systems engineer. I worked with her on many a long night sorting out program problems. I was the one who went to Casablanca to do the program program change to the AICUs that someone mentioned being removed from the aircraft and lined up on a desk in the Air France office. While I was there Turcat came in and sat at the table to watch.
I used a prom blower to blow the fusible links not a 9 volt battery, just as Liz would have done at Tangiers (the same prom blower)
Regarding the 1990s modifications to the AICU pcbs for obsolete components, I was requested by John Churchill, who designed the replacement boards, to give him some help. I was amazed that the test specs were still approved by my signature, which meant they had not changed since I moved on around 1978 when I moved to Stevenage. In about 1974ish we bought all the remaining proms as they were stopping being manufactured.
I will try and read the rest of the threads to see if anything else has been asked.