XB-70

Since there's an SR-71 thread, I figure I could get some light dawned on this amazing aircraft.
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One thing I found out recently is that Lockheed-Georgia was a subcontractor on the B-70, and the cancellation of the production aircraft resulted in a not-insubstantial number of layoffs here at the time.

 

OMG I always loved this plane!!!!! I saw it at Dayton many years ago (not my photo).
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A culmination of the B-58 and the B-52.

 

Absolutely astounding airplane. Seems to me like it was very ahead of its time.

 

Is it just me or are there similarities in form with the Concorde, are they from the same design period or share design collaboration / thinking. Impressive

 

Prototypes were three years apart.

 

At least one foreign entity copied it.
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Amazing plane and some good videos of it out there. I have a 1/100 scale model of it. Right next to my 1/100 Tu-144

 

Concorde (flew in late 60's British/French) came a few years after the B-70 (design started in the late 50's by North American - flew in mid 60's).

The Tu-144 was very similar to the Concorde.

 

So did the Soviets, with the Sukhoi T-4.
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From what I remember reading about the B70 the skin was super thin, that it required patching after every flight. That the systems werte so complex that getting it airborne and running for a test flight was a major task. The conclusion being that this was a fragile test article, not really somesthing that could be productionised or regularily flown, and order of magnitude more expesive and difficult to operate than a SR71. A manificent acheivement to get something so big to go so high and fast, but completly impractical to operate and with no defineable task. Test article 1 flew something like 85 times in total over 6 or so years. So even if there had been a bomber use it is very questionabvle that a B70 could have been a practical or viable option. Even the B58 which by all accounts was simpler to operate ended up being to complex and expensive, having alifespan of 10 years. I guess they did get it right with the B1A, although the B1B lost its supersonic ability due to no need to go high and fast.

The concorde was not as fast as the B70, but flew every day maintained at regular airports, had a cabin with comfort food and passengers. In many ways far more of an acheivement.
The TU144 could only fly suspersonic on afterburner, which severely limited range, and reports indicate it was really noisy hot and uncomfortable inside. The acheivement of concord was the speed with comfort for passengers, maintanability and operability.

 

Was the T4 a waverider like the B70, what were the results of its tests?

 

Due to the temperatures achieved as a result of the high speeds materials other than aluminum had to be used, e.g. titanium and SS. This results in thinner gages to save wt, which also results in susceptibility to damage. It is often thought that aluminum is used for aircraft structure due to superior strength-to-wt ratio. However it really is no better, if not worse, than titanium and some steels. What aluminum allows though is gage thickness that is more amenable to manufacturing and damage tolerance.

 

The first B-70 surpassed Mach 3 but because of the skin, a two foot fragment in the tip of the wing tore off, then the speed was limited to Mach 2.5.

This aircraft has the same front delta wings as the Concorde, Tu-144, and B-70.
http://en.m.wikipedia.org/wiki/Avro_730

 

The early 144's needed afterburner as they were using the only available engines; turbofans, which also limited the top speed and fuel efficiency.

Later versions had new turbojets that solved those problems and they did not need afterburner to cruise at supersonic speeds.

Cabin noise was supposedly deafening... conversation was impossible.

 

Awesome Plane

Nice vid here.

https://www.youtube.com/watch?v=Rd0mSLv7zoA

 

Ironically, I would guess something like the B-70 would have been useful in Iraq-- fast, hard to hit with low-tech SAMs, etc. Still probably not worth the expense, though.

 

The wingtips did not turn down, so I suspect that it did not ride the wave, at least as efficiently as the B-70. As the manufacturer itself admits, it never got fast enough to really find out:

http://www.sukhoi.org/eng/planes/museum/t4/

 

The wings folding down created a compressed lift that allowed it to fly at it's Mach 2.5+ top speed.

 

Is that a YF-23 next to it in the pic?

 

Yes, the "Grey Ghost" version...

in the foreground.

 

Are any of the XB-70's in a condition where they could be made flyable? Or were their "backs" broken..

 

There is only 1, inside a hangar at Museum of the USAF (Wright-Patterson AFB). Think Saturn V. Even in 1964 dollars our government nowadays would spend 3 times as much to design the thing from scratch as it did originally.

 

There were actually three built - the first was a non-flying prototype made to get down the difficult manufacturing process. The third was the one that crashed after the mid-air with the chase Starfighter. The display plane is the first flying prototype, which had numerous construction issues.

I knew a guy who was involved in the construction of these planes years ago in California. He says that much of the difficulty was due to the fact that this was intended to be nearly an all-welded airplane - hardly any rivets were used. They had to create "welding tents" by taping together plastic and filling them with argon to arc weld the titanium and SS. One worker was asphyxiated by entering one of these areas without breathing equipment.

There is a display engine in the SAC museum in Omaha, Nebraska - it is interesting that almost all the external plumbing on it is also welded or brazed - hardly any removable fitttings are used.

Perry told me that the only really flyable example was the one that crashed. He really loved this bird, but did admit that it really had no practical military purpose - other than the research value derived from making the prototypes.