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The XB-70 (2019)

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Re: The XB-70 (2019)

#21

Post by slow_typist »

Syonyk wrote: post #3

That era of aviation was nuts. I wish I was around for it. Men with slide rules working out the limits of material science, aerodynamics, and everything else, all at once. Because it wasn't enough to just push one limit, you had to push half a dozen others to get things to that first limit. And the rate of advance was just staggering. The XB70 flew in late 1964. Concorde was doing revenue flights in 1976, cruising at…

The sheer amount of gas this plane must have carried in order to fulfil its mission…

Re: The XB-70 (2019)

#22

Post by dogma1138 »

mandevil wrote: post #9
Syonyk wrote: post #3

That era of aviation was nuts. I wish I was around for it. Men with slide rules working out the limits of material science, aerodynamics, and everything else, all at once. Because it wasn't enough to just push one limit, you had to push half a dozen others to get things to that first limit. And the rate of advance was just staggering. The XB70 flew in late 1964. Concorde was doing revenue flights in 1976, cruising at…

My favorite bit of design from this era went something like this: "ooohhh, we need something that can handle high heat. How about if we made it radioactive?" and so Mag-Thor was born ( https://en.wikipedia.org/wiki/Mag-Thor ): Magnesium plus Thorium. It's creep resistant up to 350C! And it's only mildly radioactive! That's not a problem, right? Actually used on the BOMARC and D-21's ramjet engines- which is why you d…

Mag-Thor is interesting it actually has rather poor overall thermal characteristic compared to most metals since its melting point is only circa 650c pretty much the same as magnesium but it basically shrugs any heat upto 350-400c depending on the alloy so it doesn’t changes its dimensions or becomes susceptible to mechanical deformation (it’s basically as hard at 350c at it is at room temp). So it’s useful but only for very specific applications unlike say titanium. And today we have super alloys like inconel which can hold back heat creep up to 650c and it’s annealing starts at almost 900c.

Re: The XB-70 (2019)

#23

Post by colechristensen »

Enginerrrd wrote: post #7
runjake wrote: post #4

As someone who once worked on B-52s, I find it amusing how many "successors" it has outlasted. And I know why, because I worked on many of those, too. It has taught me to be skeptical of unproven claims and promises, especially when someone is particularly passionate about them. Also that simplicity is king. Complexity is the enemy. I have great respect for the XB-70. It's the only strategic bomber I haven't worked o…

> Also that simplicity is king. Complexity is the enemy. As someone that has managed engineering teams for large projects, I 100% agree. One of the issues with computers IMO is that it has made bad engineering easier. Back when you had to check everything with a slide-rule, you had a real appreciation for the skill and engineering prowess and experience to make things absolutely dead simple.

One of the sources of this, which is now over, was the exponential increase in computing power. You could add complexity and your code would always run faster anyway, one of the popular benchmarks saw worse results on average than last year which never happened before. There are a lot of reasons for it some more speculative than others, and clearly computers will get faster in the future. But still.

No longer can software engineers arbitrarily add bloat and just get away with it.

https://www.tomsguide.com/computing/cpus/new-benchmark-shows...

Re: The XB-70 (2019)

#24

Post by kjs3 »

runjake wrote: post #4

As someone who once worked on B-52s, I find it amusing how many "successors" it has outlasted. And I know why, because I worked on many of those, too. It has taught me to be skeptical of unproven claims and promises, especially when someone is particularly passionate about them. Also that simplicity is king. Complexity is the enemy. I have great respect for the XB-70. It's the only strategic bomber I haven't worked o…

Not to make this thread about the B-52, the thing has been operational long enough for 3 generations from one family to fly it: https://www.dailymail.co.uk/news/article-2430802/David-Welsh...

Re: The XB-70 (2019)

#25

Post by runjake »

gedy wrote: post #20
runjake wrote: post #19

Earlier quoted context omitted.

> I'm humbled for us laughing at the one guy assigned to B-52 maintenance role when was in USAF training over 30 years ago "That old thing? Ha!". That guy may have been me. I was pretty bummed, but quickly learned about its awesomeness (avionics-wise, anyway).

Ha, at Lowry in 1993?

Yep, up until January 1993 or so.

"SRAM Howell" ring a bell?

Re: The XB-70 (2019)

#27

Post by bediger4000 »

ge96 wrote: post #5

A beautiful plane, shame those 6 engines in line is unreal to see. Similar vibe would be the B1-lancer for engine although in 2s

The Wings Over the Rockies museum on the east side of Denver CO has a B-1A (!!!) on display. Landing gear is really tall, you can walk under the wings to see the engines.

Re: The XB-70 (2019)

#28

Post by Syonyk »

slow_typist wrote: post #21
Syonyk wrote: post #3

That era of aviation was nuts. I wish I was around for it. Men with slide rules working out the limits of material science, aerodynamics, and everything else, all at once. Because it wasn't enough to just push one limit, you had to push half a dozen others to get things to that first limit. And the rate of advance was just staggering. The XB70 flew in late 1964. Concorde was doing revenue flights in 1976, cruising at…

The sheer amount of gas this plane must have carried in order to fulfil its mission…

Per Wikipedia, the XB70 carried: 300,000 pounds (140,000 kg) / 46,745 US gal (38,923 imp gal; 176,950 L), on a maximum takeoff weight of 542,000 lb - so about 55% of takeoff weight was fuel.

A 747-8I carries up to 63,034 gallons, or about 400k pounds, on a max takeoff weight of 987,000 pounds, or about 42% of takeoff weight.

Interestingly, the ranges are about the same. The XB70's combat radius (there and back) is 3,725 nm, for a straight line range of 7450 nm, the 747-8I's range is 7730 nm.

High altitude supersonic flight is actually fairly efficient... if you can handle it.

Re: The XB-70 (2019)

#29

Post by loloquwowndueo »

gedy wrote: post #17
runjake wrote: post #4

As someone who once worked on B-52s, I find it amusing how many "successors" it has outlasted. And I know why, because I worked on many of those, too. It has taught me to be skeptical of unproven claims and promises, especially when someone is particularly passionate about them. Also that simplicity is king. Complexity is the enemy. I have great respect for the XB-70. It's the only strategic bomber I haven't worked o…

I agree with you, but the issue afaik is that B-52 was more flexible whereas the B-70 was basically single purpose and basically obsoleted by ICBMs. B-52s were able to pivot to new roles so have stayed around. I'm humbled for us laughing at the one guy assigned to B-52 maintenance role when was in USAF training over 30 years ago "That old thing? Ha!". Who would have guessed..

What killed the xb-70 was the advent of better air to air missiles that nullified its high-altitude high-speed flight advantage.

ICBMs also render other kinds of bombers obsolete and yet b52 and tu-95 are still around.

Re: The XB-70 (2019)

#30

Post by gedy »

runjake wrote: post #25
gedy wrote: post #20

Earlier quoted context omitted.

Ha, at Lowry in 1993?

Yep, up until January 1993 or so. "SRAM Howell" ring a bell?

Ah I got there 1/93 so may have missed. I remember going to "fundies", getting called "pinger", etc. Good times.
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