Some XB-70 History For You

[Skyviper 1,101]

 

 

It always amazes me how aircraft bordering on science fiction actually existed and worked (for the most part)

[+streakeagle 869]

One of my all-time favorites. I learned about it in the 3rd grade (1976-77) from the school library's Colby airplane books and was disappointed to find that it never went into service. I did find and build a model of it back then. Now I have a much bigger and better model of it hanging from my ceiling with the wingtips down and the nose raised up for Mach 3 flight :)

[Skyviper 1,101]

I learned about it in the 5th grade with those little aircraft info cards that you could put into your tracker keeper or binder. Like you I was sad to know the only thing left of the XB-70 was a few photos and some footage. Which we all know is super rare.

 

(For all you yungins out there. We used these ancient devices that held all of your papers with 3 metallic rings that would click together. We had tracker keepers and Five star binders. These book like cases had all kinds of storage. We didn't have laptops, iPads, and smartphones. Closest thing I had to smart phone was my TI-83.)

 

I know I might get smacked around for saying this. But the XB-70 so reminds me of the Concord. One of the safest aircraft in the sky I think. I believe it was a piece of FOD that ended the Cocord among other maintenance needs. But I never known one to crash.

[JediMaster 451]

Large supersonic planes will share common characteristics out of necessity. It seems either VG or delta wings (or both in the 70's case) is needed.

 

The other 70 still exists at WPAFB in Ohio, though, along with many other rare planes at the USAF museum.

[+streakeagle 869]

I have touched the one in Dayton. When I left the Navy in 1997, I drove from San Diego to Tampa on a 10,000 mile road trip. I stopped at Dayton to see the museum. I was in a hurry to get up to Boston, so I limited myself to about three hours. I climbed up on one of the front wheels so that I could touch the skin of the airframe. Even among so many other great aircraft, the XB-70 was so impressive to finally see in person. I can't wait to go back and see it again now that the new hangar is open.

[Toryu 156]

 

I know I might get smacked around for saying this. But the XB-70 so reminds me of the Concord. One of the safest aircraft in the sky I think. I believe it was a piece of FOD that ended the Cocord among other maintenance needs. But I never known one to crash.

 

The funny thing is there were plans of converting B-70s into a civillian airliner. The passengers were supposed to be seated in the space aft of the cockpit - depending on the projected pax-capacity, the neck/ crown of the fuselage would have been lengthened and thickened. Overall, the airplane was not feasible, as there would have something about 20 pax-seats max. Talk about energy-inefficiency: Hauling about 20 people at Mach 3...

 

Mach 3 is a shitty velocity to be at: It's pretty hot on the skin and you're just at a point where ram-jets make sense.

The temperatures warrant the use of steel (heavy) or titanium (expensive, a dog to machine and most of it is buried in ole commieland), driving the costs up in a spiral.

If you look at the design of the Blackbird-family with all it's special little gimmicks (heat-sinks, "flexible" fuel- and hydraulic lines, leaking JP-7 fuel on the ground, having to refuel just after take-off to keep the load on the tyres manageable, etc.) you'll see why Mach 3 only sounds great on paper, unless there's a lot more brainpower (and money) thrown at the issues.

Pour on the coal a little more and you're in hypersonic- and scramjet territory. The engineering-challenges scale about exponentially with velocity.

This is one of the reasons why Concorde was limited to about Mach 2.05 operationally: The skin-temperature was still barely manageable with aluminium. In fact, if you run the numbers, the max operational skin-temperature is 127°C or 400K. The airplane would easily go faster than that...

 

Concorde was an awesome airplane. I always argue that in many ways, it was Britain and France's equivalent to the Apollo-Programme.

It's a shame they never built the "Concorde B", which was to start at line-number #017 (they only built 16 operational airframes) and was to feature leading-edge flaps for better aerodnamic performance at subsonic-speeds*, non-afterburning Olympus engines (uprated about 25%) and roughly an additional 500NM max payload range due to an increased fuel-volume. Given the fact, that some of the lighter, later Concore airframes were already close to Concorde B's payload-range capabilities, this figure might actually be closer to 800NM-1000NM over the intial airframes.

This would have opened lots of more transatlantic connections and (more importantly!) many transpacific routes.

 

The list of reasons why Concorde wasn't to be is long and hard to single-out.

What eventually killed the airplanes in service were multible things:

- The crash of 2000 cost lots of modification-money for the re-issuance of the airworthiness certificates (lots of money invested)

- Air France wasn't really making any money with Concorde (British Airways was!)

- Airbus wasn't really enthusiastic about having to support a subfleet of 15 highly special airplanes

- 9/11 killed a lot of customers** and caused an economic downturn

- the invention of broadband internet made long-range telephone conferences possible, slightly cutting into the need of being *there* in person on a short notice

- all the airframes were nearing an age where more thorough checks were coming on the horizon, making AF (again: BA didn't feel pressed to retire Concorde!) reconsider it's need for a supersonic flagship

- Airbus and Air France signalled their reluctance of supporting Concorde in the future, which would have meant that BA care for those aircraft themselves - consequently BA had to bail out, too for financial reasons

 

___

* On a typical LHR-JFK sector, Concorde would burn about 25% of it's trip-fuel (TINS!) during the subsonic sector from London Heathrow to the acceleration-point at Land's End!

** Not just customers per se: Higher management would know about the benefits of supersonic air-travel and agree on mid-level management travel on Concorde.

Edited May 23, 2017 by Toryu

[JediMaster 451]

Concorde's demise was sealed long before the accident or 9/11.

 

It boiled down to two things--the plane wasn't profitable enough for them (even when it made a profit, they could make MORE profit with a slower plane) and the allowed routes were so limited that there was impetus to spend on a better plane. Why spend billions if it will take you decades to recoup it?

 

They are working on reducing the sound footprint of supersonic planes, though, so I believe in my lifetime we will see a replacement in service, although it may be biz jet territory alone.

[Toryu 156]

Again, Concorde was profitable for BA. In fact, the profits of the Concorde-fleet were hugely over-proportional.

 

Some quick and dirty quote:

 

However, Concorde needed the right routes, a long over-water sector between two major business locations, in other words, London and New York, which was the core of the profitability, on a double daily service.
Forget all the talk of it being a celeb service, 80% of this services pax were regular business pax, how else could you leave LHR at 10:30 am, and get into JFK at 09:20 am, ready to do business?
For that reason, the LHR-JFK were generally a bit busier than JFK-LHR.
In 1997/98, the LHR-JFK/JFK-LHR Concorde services carried only 7% of BA pax on that route, but made 30% of the revenue for BA.
For BGI services, Concorde carried 43% of BA pax when the winter Concorde service was operating, but made 75% of the revenue.
Around this time, Concorde made a profit of £30 million per year, that's only from direct Concorde pax, not counting all those pax encouraged to keep flying on BA premium services by frequent Concorde upgrades.
In fact, Concorde revenues were judged with greater rigour than other services.

[...]

Had the accident and/or Sept 11th not happened, most of the fleet reaching 24,000 hrs requiring major maintenance in around 2004/6 would have been a challenge, as experience eroded by retirements as well as the costs, in this case BA would have either proceeded with this work taking the fleet to 2009/10 or retired when AF always said they would, in 2006/7.
BA would have hoped that AF would have carried on after that had BA chosen the former, they would have needed them to really to make maintenance viable, AF had lower utilization (the oldest AF Concorde had slighly less hours than BA's youngest), but in the past AF had usually gone along with maintenance planning by BA, as of course they needed BA Concorde to be flying for their own fleets viability.

 

Source "GDB" on http://www.airliners.net/forum/viewtopic.php?t=736597

 

Another great (mostly technical) thread is this one:

http://www.pprune.org/tech-log/423988-concorde-question.html

 

At this time I'm not overly enthusiastic about the countless supersonic business-jet endeavours of the past years. They all come in with whizz-bang announcements and the PR quickly dies-off after that.

The easiest way of "staying quiet" and not booming anybody is staying below Mach 1.2 at high altitude (so the shock-wave won't reach the ground) - unfortunately, that makes you stay in an area with incresaed transonic drag. There are some interesting studies about shock-wave shaping (mainly by cutting the bow-shock into several more, weaker shocks), but other than tech-demonstartors, there haven't been any implementations yet.

Hopefully one day...

[Toryu 156]

My favourite video on Concorde:

 

 

Sorry I highjacked your thread, Skyviper

Edited May 24, 2017 by Toryu

[Skyviper 1,101]

No we're talking about the Concorde too.