US 1960's procurement without McNamara?

[Yellow Palace]

The extra mass and the seal around the canopy would be unworkable.

The space program developed seals that could hold 14.7 psi of pressure differential for two weeks when required by the Shuttle. We're asking for one that can hold 9.5 psi pressure differential for a few hours. We already have one that can hold ~4.5 psi for that period in this flight environment. It might not be a trivial engineering problem, but that's all it is - and it's not like the rest of this project is easy.

Weight is certainly a concern, and you'd be trading off some amount of speed and altitude performance to get it. The higher pressure suit also means you probably can't operate the controls after depressurisation, due to suit rigidity. On the other side of the bargain, you gain the ability to scramble with zero prebreathe, which is a massive advantage for an operational interceptor. I'd expect that, unless the loss in speed and altitude is really significant, the heavier cabin would be worthwhile.

 

[Scott Kenny]

The extra mass and the seal around the canopy would be unworkable.

The Blackbird cockpit was already pressurized. Just not to 10psi. IIRC it was pressurized to 5psi, and the pilots breathed pure oxygen at that pressure. At 10psi, you can use standard air mix or slightly enriched with oxygen. Because 10psi is the pressure at 10,000ft and people sitting down thinking don't need a whole lot of extra oxygen.

Extra mass may-or-may-not be an issue, depends on how strong the structure was to begin with. Given 1950s/60s, it's probably twice as strong as it needs to be for 10psi pressure differential.

 

[Michel Van]

On B-58
There was proposal for B-58B a stretch fuselage uprated engines around 1958, the entire project was canceled do budget issue.
Follow by proposal B-58C with enlarged version of the B-58A to be powered by Pratt & Whitney J58 turbojet engines.
Also the B-58C carrying a more varied assortment of weapons, including conventional bombs.
But the program was canceled in 1961.
Sound like the work of McNamara, who was in time obsessed by ICBM as low cost alternative to strategic bomber...

 

[Michel Van]

We talk about what if McNamara never became secretary of defence.
but over looking some projects like Dyna Soar and Blue Gemini
realistically Dyna Soar would died under every other SecDef, over budget, far behind schedule, loosing it goals to unmanned System.
Either replace by Blue Gemini or Apollo derivate unter USAF.

But there is radioaktive Mammoth in this discussion, staring evil at us...

During 1950s the USA was working nuclear weapon systems and Doomsday weapons.
most infamous was SLAM / Pluto a nuclear ram jet powert cruise missile with 26 War heads on board.
Or the proposals of Nuclear bomb power Orion Battleships, who dump thousand of warhead from high orbit.
Other were proposal to salt the US ICBM warheads with Kobalt-60 or Gold to make them very deadly.
And the World ending device of the Doomsday weapon, the absolute deterrence

McNamara was intelligent to cancelling all of those madness projects.
but with other SecDef ?
i could imagine that scale down SLAM (like Convair big stick) get into service
or that ICBM warheads get salted...

 

[Yellow Palace]

Among those projects:

• Pluto wasn't cancelled until the mid-1960s - that wasn't a kneejerk cancellation by McNamara, but a project that was allowed to run its course and cancelled when it became apparent that it was unworkable.
• Orion was killed primarily by the Partial Test Ban Treaty; the 'space battleship' versions were probably more demonstrations of what could be done than serious proposals for construction.
• Salted nuclear weapons are one of those things that seem to come up occasionally. I've never heard any suggestion that they were actually considered as weapons, just that those terrible awful people Over There might use them.
• I'm not even sure what you're referring to as a 'doomsday weapon' - possibly Teller's SUNDIAL gigaton-class weapon? If so, that was rightly killed off as impractical in the 1950s.

Tellingly, three of the four were shut down as soon they came anywhere near the people who'd actually use them. The likes of LeMay and Power might have been looking for useful weapons to use against the USSR, but they had to be useful weapons.

All of which is to say, they were almost certainly not going anywhere. They were pipe dreams or theoretical concepts from R&D departments.

 

[Scott Kenny]

Among those projects:

• Pluto wasn't cancelled until the mid-1960s - that wasn't a kneejerk cancellation by McNamara, but a project that was allowed to run its course and cancelled when it became apparent that it was unworkable.

Pluto wasn't unworkable. In fact, the basic design is quite solid and should work just fine. (NASA is looking at that engine for a planetary atmospheric probe, for example)

The problem was flight testing the thing.

 

[1635yankee]

I mentioned that as I remember seeing something about replacing nitrogen in breathing mix with argon. That may have been for divers, as nitrogen under high pressures causes weird mental effects that aren't an issue in flight because the gas pressures stay low. The usual diver's mix for high pressure is helium-oxygen, which makes squeaky voices and would likely cause issues for pilot's communications.

In general, I'd want to pressurize either the suit or the cockpit to about 8-10psi (10kft equivalent pressure), and the cockpits are pure nitrogen like the X-15. Below that pressure and the bends turns into an issue.

I forgot helium.

I would be very surprised if argon would be considered for deep diving as pressure narcosis increases with atomic or molecular mass, so argon would likely be worse than nitrogen. Heliox diving gas is not used to avert the bends, but to avert narcosis.

The bends isn't really a pressure issue, but a drop in pressure issue.

 

[Byeman]

1. The space program developed seals that could hold 14.7 psi of pressure differential for two weeks when required by the Shuttle.

2 We're asking for one that can hold 9.5 psi pressure differential for a few hours. We already have one that can hold ~4.5 psi for that period in this flight environment.

1. On a circular hatch less than 3 foot across. That is easy, especially with the shape, the ease of reinforcement and minimal seal length.
2. Double the pressure, increase the hatch area (3-4 time larger), longer and complex seal path.
5 psia increase is 5000 lb more force on the shuttle hatch equivalent, 15,000 - 20,000lb on the SR-71 canopy.

Also, all the penetrations for wiring and controls have to be stronger.

 

[Byeman]

The Blackbird cockpit was already pressurized. Just not to 10psi. IIRC it was pressurized to 5psi, and the pilots breathed pure oxygen at that pressure. At 10psi, you can use standard air mix or slightly enriched with oxygen. Because 10psi is the pressure at 10,000ft and people sitting down thinking don't need a whole lot of extra oxygen.

Extra mass may-or-may-not be an issue, depends on how strong the structure was to begin with. Given 1950s/60s, it's probably twice as strong as it needs to be for 10psi pressure differential.

That would be wrong. See above, 5 psia difference is a big deal.

 

[Michel Van]

Pluto wasn't cancelled until the mid-1960s - that wasn't a kneejerk cancellation by McNamara, but a project that was allowed to run its course and cancelled when it became apparent that it was unworkable.

The Pluto nuclear ram jet worked as planed
it was as they wanted test fly hardware, McNamara stop SLAM.
The SLAM autopilot ended up modified in other program: the Cruise Missile

• Salted nuclear weapons are one of those things that seem to come up occasionally. I've never heard any suggestion that they were actually considered as weapons, just that those terrible awful people Over There might use them.
• I'm not even sure what you're referring to as a 'doomsday weapon' - possibly Teller's SUNDIAL gigaton-class weapon? If so, that was rightly killed off as impractical in the 1950s.

Those salted nukes were proposals mostly from Los Alamos, RAND corp., DAPRA
look for Herman Kahn Book On Thermonuclear War for more.
Teller proposed clean nukes, McNamara refused, knowing this make Nuklear war easy !

on Doomsday Weapon,
Those men can explain concept much better, as me:

View: https://www.youtube.com/watch?v=-mUCLHzWiJo


RAND corp. made allot studies on Doomsday weapons,
Soviet look also into Doomsday weapon.
For obvious reasons they abandon concept...

 

[Scott Kenny]

That would be wrong. See above, 5 psia difference is a big deal.

Yes, it's a big deal, but given how people tended to design things in the slide rule days (Math says X, so let's double that and then add safety factor)...

 

[Yellow Palace]

Pluto wasn't unworkable. In fact, the basic design is quite solid and should work just fine. (NASA is looking at that engine for a planetary atmospheric probe, for example)

'Can't be test flown' is pretty unworkable for an operational weapons system, in my book.

Those salted nukes were proposals mostly from Los Alamos, RAND corp., DAPRA

Yep, a bunch of R&D folks - the operators wanted nothing to do with them. Ditto the 'doomsday weapons' - they were never anything more than 'this is theoretically possible but stupid, let's keep an eye out for the Bad Guys doing it'.

The clean bomb is an interesting idea, and the idea that it would make war too easy is the kind of nonsense I'm all for criticising McNamara over. I don't think reducing the radiation hazard would make killing tens of millions significantly more appealing to anyone who's fit to lead.

1. On a circular hatch less than 3 foot across. That is easy, especially with the shape, the ease of reinforcement and minimal seal length.
2. Double the pressure, increase the hatch area (3-4 time larger), longer and complex seal path.
5 psia increase is 5000 lb more force on the shuttle hatch equivalent, 15,000 - 20,000lb on the SR-71 canopy.

Also, all the penetrations for wiring and controls have to be stronger.

A big deal, but an engineering problem, not one of fundamental mechanics. Doubling the pressure differential on the penetrations is easy. Thickening the pressure vessel is easy.

The cockpit seals are the hardest part, but still not fundamentally different. Broadly speaking - double the number of catches, add more seal material. The kind of pressure differential we're talking about is actually slightly less than that used on Concorde, which maintained 10.7psi with fare-paying civilians on board.

You could even compromise and run a ~7 psi atmosphere. That's about as low as you can go without the need to prebreathe. I suspect it isn't coincidence that that's also what a 5 psi differential gets you at ~50,000 feet, where US regulations (based on 5 psi differential) require a pressure suit.

I'm not claiming it's a trivial change, but it's not one that should be beyond a competent design team. There'll be an increase in weight, but a slightly heavier aircraft that can actually perform the mission is worthwhile.

 

[Byeman]

Yes, it's a big deal, but given how people tended to design things in the slide rule days (Math says X, so let's double that and then add safety factor)...

No, it was never done that way in aerospace. Just the factor of safety of 1.25 to 1.4.
You don't get to orbit or Mach 3.2/80k feet by "doubling" figures.
Slide rule days were just not to the same significant figures.

 

[Scott Kenny]

'Can't be test flown' is pretty unworkable for an operational weapons system, in my book.

More like "can't be recovered and analyzed once the reactor lights off". You can test fly them just fine as long as you dump the airframe into the ocean at the end of flight.

Which gets interesting for testing the aerodynamics. Have to build some rocket or ramjet to test with, even if it will only fly for a couple hundred miles at speed before you run out of fuel.