The XB-70 (2019)

Golden age of aviation and XB‑70’s aesthetics

• Many commenters express awe at 1960s aviation: slide‑rule engineers pushing multiple limits (materials, aerodynamics, propulsion) simultaneously.
• The XB‑70 is described as uniquely futuristic—“nothing before or after looks like it”—and the visual impact in person at the USAF Museum is heavily praised.
• Several people recount museum visits; the XB‑70 is repeatedly called the “crown jewel” among already exceptional aircraft.

Extreme technology, materials, and fuels

• Discussion of Mag‑Thor (magnesium + thorium) highlights how far engineers went: a mildly radioactive alloy with excellent creep resistance up to ~350–400°C but a low melting point, useful only in narrow cases.
• Commenters contrast it with modern superalloys like Inconel that withstand far higher temperatures.
• Zip fuel and HEF‑3 are cited as another example of extremity: theoretically higher‑energy fuels abandoned after cost and technical hurdles proved prohibitive.

Fuel load, performance, and design

• Numbers from references: XB‑70 carried ~55% of its takeoff weight as fuel, versus ~42% for a 747‑8I, yet with similar range, illustrating the efficiency of high‑altitude supersonic cruise.
• The prototypes lacked in‑flight refueling, but production aircraft were expected to have boom receptacles like other USAF bombers.
• A question about “why six engines instead of four larger ones” goes unanswered; engine configuration rationale remains unclear.

Strategic role, obsolescence, and SAM vs ICBM debate

• Several argue the XB‑70 lost its purpose once Soviet SAMs could reach high, fast bombers; others emphasize ICBM and cruise‑missile advances as the real killers.
• One detailed comment explains that massive Soviet SA‑5 deployments prompted US fears of ABM capability, accelerating MIRV development and extreme warhead counts.
• Others note that, despite strategic failure as an operational bomber, the program spun off valuable technologies and experience.

B‑52 longevity, simplicity, and alternatives

• The B‑52 is contrasted with the XB‑70: flexible roles, relatively simple/robust design, and enduring utility as a “bomb and missile dump truck.”
• There’s skepticism toward complex, fragile systems (B‑2/B‑21, JSF) and US practice of shutting down production lines, making losses irreplaceable.
• Heated debate over re‑engining B‑52s (8 old engines vs 4 modern ones) and whether commercial airliners could be converted into cheap strategic bombers; practitioners strongly dispute that conversions are straightforward.

Modern warfare, deterrence, and vulnerability

• Commenters disagree on how a US–China or US–Russia conflict would unfold: some expect rapid nuclear escalation, others stress economic/cyber/proxy warfare and the value of conventional options like B‑21.
• There’s concern that high‑end aircraft are increasingly at risk on the ground from missiles or cheap drone swarms; forward basing vs homeland basing trade‑offs are debated.

Engineering culture and complexity (aviation to software)

• “Simplicity is king; complexity is the enemy” recurs as a theme, extended from aircraft to software.
• Some argue computers made it too easy to add complexity; now that CPU gains have slowed, software bloat is less tenable.
• Others point out that modeling and rapid iteration can yield non‑obvious but effective complex solutions (e.g., reusable rockets).
• A distinction is drawn between unavoidable problem complexity and avoidable “complication” introduced by design.

Safety systems and extreme operating regime

• The XB‑70’s ejection capsule system—enclosing the seat in a capsule before ejection to survive Mach‑3/70k‑ft conditions—is highlighted as “next‑level engineering,” with linked technical documentation admired.