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Virgin Galactic and Boom unveil Concorde 2.0 tester to restart supersonic travel

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Interesting ...

When any aircraft passes the critical mach for its rated airframe, the centre of pressure shifts rearwards. I wonder if that would be why they are using a rear engine, given that the noise for passengers at the rear of the jet is going to be pretty horrendous at Mach 2.2?

IIRC Concorde compensated by using a system to redistribute fuel along the aircraft during acceleration and deceleration.

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Re: Interesting ...

With regard to the interior noise, maybe the idea is to only use the rear fuselage-mounted engine for take-off/climb/acceleration, and cruise on just two? Admittedly that's a pure guess as the technical content of the article is so poor ("ungainly" at low speed, no mention I could see of its actual top speed, and surely the range of any aircraft can be doubled by refuelling???) and there's no link to anything more informative.

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Re: Interesting ...

Would the rear of the cabin suffer from more noise at mach 2.2 if the aircraft is flying faster than the sound shockwaves it is creating? The intake and engine look to be well behind the last window in the cabin. The description says no reheat (which was the noisiest part of a Concorde take off and the brief acceleration through mach 1).

Maybe the noise will come from the intake design which shockwaves the incoming air down to subsonic speeds and vibrations from the turbine.

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Re: Interesting ...

Whilst the XB-1 sounds intriguing the XB-70 Valkyrie would be my preferred way to cross the Atlantic.

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Re: Interesting ...

As with all three baggers, it's got one in the tail and two more conventionally mounted.

The two cannot go either side of the fuselage at the rear due to the tailless arrangement, so they're beneath the wings, where Concorde's were.

I suspect that's all the engine position considerations there were....

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Re: Interesting ...

"When any aircraft passes the critical mach for its rated airframe, the centre of pressure shifts rearwards."

You're using some random buzzword generator, aren't you?

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Re: Interesting ...

How about the Tu-154?

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Re: Interesting ...

> Would the rear of the cabin suffer from more noise at mach 2.2 if the aircraft is flying faster than the sound shockwaves it is creating?

The internal air is going at roughly the same speed as the passengers and engines, as is the airframe. Engine noise could reach the passengers just fine through those routes.

Passengers seated on the wing may have trouble hearing the tail engine, though.

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Re: Interesting ...

Do you perhaps mean the Tu-144?

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Re: Interesting ...

The Tu-144 had three engines?

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Re: Interesting ... @CraPo

Oops - thought your reply was relating to a different section of the thread.

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Re: Interesting ...

I flew (once) on Concorde LHR to JFK, which is another story entirely, I think that I heard about as much afterburner noise inside the cabin as you might hear from a normal aircraft acceleration at take-off, and I was about 5 rows from the back, so closer to the engines.

Mind you at that point you are mostly wondering why your kidneys just broke through your back and ended up in the champagne glass of the chap sitting behind you.

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Re: Interesting ... XB-70?

A blackbird would be a lot more fun and very slightly faster.

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Anonymous Coward

Wheels in the Wings Design Flaw

Will be interesting how they get around the fundamental design flaw of having the wheels within the wings, next to the fuel tanks. Supersonic Jet travel will always be associated with a 30cm strip of metal. Like the Shuttle, penetration from debris, just couldn't be designed out.

Is there any point? When you'll literally be crawling on the M25 for hours beforehand to get to Heathrow, while the new runways are built (and likely after).

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Devil

Re: Wheels in the Wings Design Flaw

That is valid for all aircraft. Your basic village bus 320 has the tanks in the wings too.

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Re: Wheels in the Wings Design Flaw

But Concorde had a thin wing section and lighter smaller undercarriage to fit in there along with the higher take off roll speed, rotating at 200 knots, compared to 150ish for a B747. Relative loads were very different.

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Re: Wheels in the Wings Design Flaw

Tire-related catastrophe is something that can happen to any aircraft. The deadliest DC-8 crash in history (Nigeria Airways Flight 2120) was triggered by a tire bursting and catching fire on takeoff.

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Re: Wheels in the Wings Design Flaw

Relative loads were very different.

Sorry dude, you have failed to grok the root cause and the actual design flaw.

What happened to the Concorde at Charles De Gaulle could have happen to any aircraft. The difference between 200kt and 150kt is minimal - a piece of hardened steel bouncing of a wheel will puncture the tank in either case.

The difference is the aftermath. Due to the way the engines are positioned on the Concorde the whole wing caught fire because the leaking fuel went straight into the afterburner exhaust. The exhaust temperature of a normal non-afterburning turbofan even cranked to max is usually too low to set jet fuel on fire. There is a whole raft of aircraft incidents with fuel leaks out of wings, not one of them caught fire. Example: https://en.wikipedia.org/wiki/Air_Transat_Flight_236 - the leak was out of the engine itself. That would have killed a Concorde there and then. Do not even get me started on oil and hydraulic fuel leaks. If you walk around budget airline craft on an airfield - half of them have traces of these. Once again - some of these would have set a Concorde on fire.

This is the main reason why they were taken out of circulation - no matter how you armor fuel tanks and lines, shit happens - fuel leaks, oil leaks, hydraulic fluid leaks - they all can burn. This is why an afterburning engine is a no-go for civil aviation - it will set that on fire straight away.

This is what makes this new supersonic aircraft interesting - it is claimed to be non-afterburning. If it is non-afterburning on takeoff it will succeed where Concorde failed regardless of how small is its undercarriage and what level of armor does it have on its fuel tanks.

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Re: Wheels in the Wings Design Flaw

"Due to the way the engines are positioned on the Concorde the whole wing caught fire because the leaking fuel went straight into the afterburner exhaust"

None of the engines on Concorde were ever actually on fire (though the crew did get a false fire alarm on one of them). The deluge of fuel rushing over them basically drowned them - they were deprived of airflow and flamed out. The probable ignition source was a damaged wiring loom for the landing gear retraction mechanism.

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Re: Wheels in the Wings Design Flaw

I think Voland carefully omitted the bit about the thin wing section.

And 200 Knots is a lot more of a difference in load compared to 150 than 33% would suggest.

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Re: Wheels in the Wings Design Flaw

The difference between 200kt and 150kt is minimal - a piece of hardened steel bouncing of a wheel will puncture the tank in either case.

It's not minimal, but it may be insignificant depending on how strong your tank is.

Kinetic Energy = 0.5 x Mass x Velocity squared.

If we assume an aircraft of mass = 1 (to keep the sums easy), we get:

0.5 x (150^2) = 11250 units of KE

0.5 x (200^2) = 20000 units of KE

The one-third increase in velocity is the result of a 78% increase in KE.

So yes, going from 150 to 200 is very significant in energy terms.

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Re: Wheels in the Wings Design Flaw

Um, no.

Air France refused to accept the weight penalty of fitting the spall liners in the wings as it would have meant either using more fuel or having less range - British Airways fitted the liners and survived a number of impacts that would have punctured the Air France jets' tanks.

And oil and hydraulic leaks? I take it you have only ever worked in IT because if you had any experience with aircraft you would know the sodding things always leak! They're like cars or any other vehicle - all you can do is keep the leaks as small as possible.

The SR71 Blackbird was (in)famous for needing to have drip trays underneath as fuel was constantly dripping out through gaps in the airframe, and the only reason you see fluid stains (both lubricants and hydraulic) on a budget line more than on someone like BA or American is that the budget brigade have a quicker turn-around and therefore less time for someone to wipe the stuff off.

And for anyone who doesn't already know, you don't need afterburners to go supersonic - the English Electric Lightning, the 1960's fighter, could easily break the sound barrier without needing afterburners - but it took longer, and the less time you spend in the area around the speed of sound the better - the stress on the airframe increases to the transition point, then decreases again on the other side.

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Re: Wheels in the Wings Design Flaw

> So yes, going from 150 to 200 is very significant in energy terms

That's the speed of the aeroplane, not the metal strip. While the certainly might be related, let's not pretend to understand the physics of a complex accident with a smarmy 2 line armchair calculation on an internet forum.

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Re: Wheels in the Wings Design Flaw

The SR-71 and it's predecessor the A12 leaked fuel on purpose.

The Airframe was designed for operating at sustained Mach 3+, the resultant heating of the Airframe (even with Titanium) at those velocities resulted in quite an expansion of the Airframe.

So panel gaps were set such that at Mach 3+ the heating would seal the Airframe and subsequently the fuel tanks.

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Re: Wheels in the Wings Design Flaw

That's the speed of the aeroplane, not the metal strip.

Bingo.

None of the engines on Concorde were ever actually on fire

I never said they themselves were on fire. I said they set it on fire.

The afterburner exhaust setting the leaking fuel on fire was the initial conclusion of the investigation.

While short from electrics and the flameout (which you mention) have been raised as a possible cause as well later on, neither was proven so the afterburner setting it on fire has always remained as one of the probable causes.

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Re: Wheels in the Wings Design Flaw

Will be interesting how they get around the fundamental design flaw of having the wheels within the wings, next to the fuel tanks.

Air France Flight 4590 didn't have a problem with the wheels being in the wings - landing gear in or under wings is a common design feature of aircraft. The Concorde's problem stemmed from a high takeoff speed, which demanded high pressure tires. If a tire did burst, it had higher pressure and higher rotational speeds to fling chunks into the wings than in other airliners. There had been seven severe cases of tire explosions on prior Concorde flights.

Meanwhile, the thousands of non-passenger supersonic aircraft flying these days do not have a reputation for tire debris damage.

Supersonic Jet travel will always be associated with a 30cm strip of metal.

I always thought the iconic image of supersonic passenger travel was in the movie Snatch.

Like the Shuttle, penetration from debris, just couldn't be designed out.

Sure it could. After Air France 4590, the Concorde finally got Kevlar tank liners. Alternately, there are proposal for tire debris fairings.

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Boffin

" what makes this new supersonic aircraft interesting - it is claimed to be non-afterburning"

Not really.

Concorde's mfg were well aware they were the only civil aircraft with reheat and had they got to a 17th Concorde one of the upgrades was deleting it, due to design improvements they'd identified from flight data.

People also forget Concorde did not fly in 'burner above about M1.2, IE it was just used to punch through the sound barrier. It was "super cruise" before most people ever used the term..

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"he SR-71 and it's predecessor the A12 leaked fuel on purpose."

Something I found out only recently, so did Concorde.

Apparently the air frame grew so much in flight their was a pronounced gap between the back wall of the Flight Engineer's console and the rear cockpit bulkhead which you could put your fingers into.

Closed up by the time it came to a halt.

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No overland

So, no chance in a Sydney to London route (or even Manchester - Leeds would be a pipe dream) with a stop off at Dubai for refuel, as that is a trip I really could do with reducing the time on = (

Not that I'd be able to afford a ticket for that, given $5k for London to New York you'd be saying what, $10k for such?

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Re: No overland

Well, it could do the distance, max range is 17,668km and London to Sydney range is 16 991km, although it calls for a brief tech stop for flights over 8000km, which might mean its a deal breaker depending where that is.

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Headmaster

Re: No overland

With this, I wonder if you'd save time going the long way round?

ie. Sydney to Honolulu to San Francisco supersonic, subsonic to New York, supersonic to London.

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Re: No overland

Even better if it avoids stopping in the USA or even going through US airspace...

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Devil

Re: No overland

So, no chance in a Sydney to London.

In theory - that route is 70%+ over water and the rest over deserts where you can negotiate to remain hypersonic too so doable. The only slow stretch is the first 45 minutes over France.

In practice - 10h vs 24 hours stops making a lot of difference - you lose a day. That is different from 10h vs 3h (especially flying west) - you do not lose a business day and this is what Concorde passengers were actually paying for.

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Re: No overland

I think the solution to getting to Sydney from northern hemisphere locations will eventually come from suborbital flights. A long way in the future though.

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Re: No overland

<confused>Manchester to Leeds via Dubai?</confused>

Seems a bit of a long way round (though better than the current train service most days)

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Re: No overland

Waaaaaaaaaaaait a second.

Everywhere I see Boom mentions 9000nm refueled/4500 unrefueled.

WTF is refueled? Where? How? Are we talking about landing or they have gone off the deep end looking to do in-air passenger aircraft refueling

There is a fairly limited number of options to land for a refueling stop in the Pacific between Sydney and Hawaii and practically none between LA and Japan unless you fly around the Pacific rim instead of direct. That kinda limits what this aircraft can be used for.

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Re: No overland

My understanding was that it was the trans-sonic bit (that actually generates the sonic boom) you weren't supposed to do over land. An aircraft at 60,000ft isn't going to going to be heard by anyone on the ground no matter fast it's going (that's over 11miles away).

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Re: No overland

WTF is refueled? Where? How? Are we talking about landing or they have gone off the deep end looking to do in-air passenger aircraft refueling

They're talking about a brief landing without de-planing passengers.

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Re: No overland

Reaction Engines proposed Lapcat A2 has a 20,000km range and flys at Mach 5.2 (6,400 km/h):

https://en.wikipedia.org/wiki/Reaction_Engines_A2

You'd be able to fly London to Sydney in about 4.6 hours via the north pole.

At those speeds you could fly over the north pole and then onto west coast US cities or east Asian coastal cities all over water in under 4 hours.

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Re: No overland

There is a sonic boom created for the entire time you are above mach 1, not just when you are transonic.

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Thumb Up

YIPPEE! Great news!

Certainly with today's technology they can make supersonic passenger flight a viable option (for some folks, anyway), especially on a smaller scale than Concorde. Gotta admit, one huge regret for me is never having flown on the Concorde. I watched it fly at the Oshkosh annual fly in many years ago and it was simply gorgeous (and freakin' noisy!). If this new triple-engined XB-1 comes to fruition I will definitely have to put it on my bucket list. ;^)

ZOOM ZOOM!

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Re: YIPPEE! Great news!

My mother won a trip on Concorde (a short circumnavigation of the British Isles and a sprint up to full speed). I was so jealous that I didn't get the ride. I do remember watching the takeoff though, that noise punches you in the chest in a way nothing else does. It was glorious.

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Re: YIPPEE! Great news!

I had a short flight (also won in a completion), we went out to the Bay of Biscay and to full operational altitude and speed. And whilst the view at 60,000 feet was incredible, I cannot even begin to properly describe what the take off and climb out feels like on a light Concorde with a reduced fuel load and no baggage.

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Re: YIPPEE! Great news!

@passive smoking.

Never seen a Vulcan do a pass and veer away from crowd with afterburners on then...!!

(Or indeed a Tornado doing a shock and awe pass)

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Re: YIPPEE! Great news!

Find me a picture of a Vulcan with Afterburners please. I'd love to see it.

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Now this is stupid. Fuel and airframe costs didn't kill the supersonic travel, Noise restrictions did.

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In technology, whenever someone proposes trying X again, the essential questions are why did X fail last time and what's different now.

Last time round, no-one paid much attention to noise during design but happily for the designers, 70% of the planet is covered in water. Nevertheless, the economic case was damaged by the quadrupling in price of the fuel between design (1960s) and operation (1970s).

Whether it is true or not, the article claims that both noise and fuel problems can be mitigated by using materials and designs that were not available half a century ago. That is unproven, but perfectly plausible, given that Concorde was designed using the same technology that put two men on the moon using wooden spacecraft, pencils, hand-caclulations and strong underpants.

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Silver badge

Fuel and airframe costs didn't kill the supersonic travel, Noise restrictions did.

Actually, it was that there wasn't an end to end business case. BA might have eventually run Concorde profitably in an expensive niche market, but the British and French taxpayers never saw a return on the vast costs of development because no genuine commercial sales were made.

Launching an aircraft that used three times as much fuel and carried a third of the passengers of the then new wide bodied format, at the same time as the OPEC embargo was never destined for success. The oil crisis probably couldn't have been predicated, the move to wide body could. There was a further economic price, and that was the opportunity cost of Concorde - the huge technical challenges of SST development forced the Anglo-French aviation industry to put all their eggs in the supersonic basket, whilst Boeing, McDonnell Douglas and Lockheed bet successfully on wide body, and thus owned the global wide-body market for the subsequent four decades..

So that's what killed SSTs - that they might be economic if you give them away, but there is no business case for development and building. We'll see if Beardo's people can do things differently - I suspect they'll find that they are no more able to overcome the technical and certification issues than Airbus or Boeing.

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" the huge technical challenges of SST development forced the Anglo-French aviation industry to put all their eggs in the supersonic basket, whilst Boeing, McDonnell Douglas and Lockheed bet successfully on wide body, and thus owned the global wide-body market for the subsequent four decades"

Completely wrong! The 747 was designed by Boeing's "B" team (excellent BBC documentary on it) whilst the "A" team worked on the Boeing 2707 SST; the expectation was that wide-bodies would become cargo planes whilst passenger traffic moved to SSTs but, for the same reasons that Concorde never made any money, the SST project was cancelled.

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What killed Concorde was the development of the 747. First generation 747s needed a significant occupancy in First Class to be profitable, but all potential First Class passengers will opt for supersonic travel if available. So you couldn't run a mixed fleet of Concordes and 747s, and the market opted for the 747.

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