21 July 2013

Space reentry vehicles, part 3


Part 3: ICBMs and the cold war

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Other than vehicles with a detached shock wave, all aircraft heat up more the faster they move.  From the NASA book Facing the Heat Barrier: A History of Hypersonics [1]
At Mach 3 and higher, there was the Lockheed SR-71 that cruised at 85,000 feet. The atmosphere at such altitudes, three times higher than Mount Everest, has a pressure only one-fiftieth of that at sea level. Even so, this airplane experienced aerodynamic heating that brought temperatures above [260C] over most of its surface.
The SR-71 Blackbird gets to 260C over most of its surface.  Aluminium anneals (softens) at 177C (alloys can be higher) making it unsuitable as a material for use on the outside of the Blackbird.  The Blackbird used titanium instead.

This temperature of 260C is in a vehicle moving at Mach 3.



The US Air Force's experimental rocket X-15 moved at Mach 5 and was designed to withstand temperatures of 1240F (671C) in some places.  If Mach 5 takes the temperature beyond the aluminium melting point (660C)*, how did the Apollo reentry capsule hold together at Mach 36?


pg 60 of [1]

In 1967 a version of the X-15, the A-2, broke a new record, reaching Mach 6.7 and was significantly damaged, but the Apollo craft was A-OK:
The X-15 reached Mach 6.7 in 1967, half the speed of an X-17 nose cone, and at 102,000 feet. Its structure was Inconel X heat sink, and it had further protection from a spray-on ablative. Yet it sustained significant physical damage due to high temperatures and never again approached that mark. [1]

The X-17 experimental rocket flying at Mach 15.5, altitude 98,000 feet, was heating at a rate of 2927C per second, and completely disintegrated. Yet Apollo moves at Mach 36 and is fine. X-17 moves at half that speed and completely disintegrates.  Its nose cone lived long enough only to return data; then it vanished into thin air.
Another noteworthy flight involved a five-stage NACA rocket that was to accomplish its own over-the-top mission. It was climbing gently at 96,000 feet when the third stage ignited. Telemetry continued for an additional 8.2 seconds and then suddenly cut off, with the fifth stage still having half a second to burn. The speed was Mach 15.5 at 98,500 feet. The temperature on the inner surface of the skin was 2,500ºF, close to the melting point, with this temperature rising at nearly 5,300ºF per second.[1]
How then did X-17 nose cones survive flight at nearly this speed, but at little more than one-third the altitude? They did not. They burned up in the atmosphere. They lacked thermal protection, whether heat sink or ablative...  pg 44 [1]

Reference [1] continues:
An ICBM nose cone was to re-enter the atmosphere at speeds above Mach 20. Its kinetic energy would vaporize five times its weight of iron. 


Really 5 times its weight?!  Just as well NASA invented the detached shock wave to protect those poor astronauts who were returning from space, otherwise they would have fried to a cinder!
Temperatures behind the bow shock would reach 9000 K, hotter than the surface of the Sun. 
There isn't a substance in the universe that can withstand 9000K!  
Research scien­tist Peter Rose wrote that this velocity would be “large enough to dissociate all the oxygen molecules into atoms, dissociate about half of the nitrogen, and thermally ionize a considerable fraction of the air.” pg 30 [1]
The Apollo reentry capsule was to move at Mach 36.  


The Apollo reentry capsule was basically made of aluminium on the top*.  How did this aluminium not soften, melt and boil during reentry?  (*Edit 3/8/13: only the outside, and part of the structure was made of aluminium.  It also had some ablative panels. And some glass windows.  Update here.)

In the first two parts of this post I argued that any vehicle returning from space will be destroyed by the huge heat of reentry.  Before NASA invented the fictitious mechanism of the detached shock wave this is exactly what was found:
"....no matter how streamlined the shape, or how super-duper the construction of the missile 'nose-cone', it came back to Earth a charred mess."
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In 1957 the world's first satellite, Sputnik, sent shock waves through the American public who thought: if the Soviets can launch a satellite over our country, they could also send nuclear weapons.  This gave rise to the missile gap.

In truth, the nuclear ICBM threat from the Soviets wasn't that bad, even by conventional estimates.  The Soviets had only 4 ICBMs in 1957 and they were easy to detect, and took 20 hours to launch. 

US President Eisenhower was fully aware of how insignificant the alleged ICBM threat was.  The American military has always had superior nuclear weapons delivery systems based on traditional platforms like the B-52 bomber -- a platform that's maintained to this day.

Sputnik was a huge propaganda victory for the Soviets.  I think if Eisenhower had his way he just would have let it slide: so what if the Soviets had a tin can in space?  It really didn't mean anything.  And that was the attitude the Eisenhower administration took at first.

The US public put a lot more credence in the capabilities of space vehicles.  The 1950s was a time of almost unlimited dreaming, and unlimited promises, of space's potential.  People didn't realise how difficult a challenge space would turn out to be.

The Jetsons: the promise of a new space age that never came to be

Eisenhower decided he would play the space race game even if it was just for show.  After the launch of the Sputnik II on 3 November 1957 Eisenhower ordered his chief rocket scientist Wernher Von Braun to fast track the latest missile project, and 90 days later the US sent their first satellite into space, the Explorer I.


Von Braun (right) and Explorer I (from here)

Eisenhower tried to placate the American public, who were concerned about the missile gap, with a TV address on November 7, 1957 where he triumphantly displayed a nose cone from a missile that had supposedly been "...hundreds of miles to outer space and back." [3].

Eisenhower displays a nose cone from a Jupiter-C missile

It doesn't look to me like a particularly blunt nose cone.  The rounded end is somewhat blunt but is only small portion of the nose cone which is mostly tapered and conical. The nose cone was in good shape being practically untouched by the heat of reentry (video). 

Given that everything else up to that point had come back from outer space a charred mess, this missile couldn't have gone as high as Eisenhower claimed.

I couldn't find a single photo of a truly flat, blunt missile nose cone on the internet, like this one I doctored up: 

What a missile with a truly flat, blunt leading edge might look like if they actually existed.  You won't see one like this though.
From the beginning, propaganda was a distinct element of the space race, but in 1961 the Soviets took it up a notch with the announcement of the first man in space, Yuri Gagarin.

Gagarin pictured wearing a parachute outfit.  Strange outfit to wear into space.

The strange part of the story, which the Soviets covered-up at the time (to preserve its eligibility as an official space flight), is that Gagarin was not in the Vostok but supposedly ejected from the capsule and parachuted down next to it.  That doesn't sound right to me; it seems more likely that he and the capsule were both ejected from a plane with their respective parachutes open from the beginning.

The Vostok space capsule was supposed to have been fitted with a camera.  See the evidence here:

Vostok

But when it came to Yuri Gagarin's mission they conveniently forgot the camera.  As a result there's not a single photo of Gagarin's alleged space exploit.  But people worldwide, including most in America, believed it anyway just on the Soviet's hearsay!  (The forgetting the camera thing is a trick they do even to this day in the Soyuz.)

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Now, if the Russians had ICBMs by 1957 and had sent a human to space and back by 1961, then why was there a Cuban missile crisis in 1962?  If nuclear missiles could be launched to America from the centre of Russia as easily as from Cuba, why should US President Kennedy care where the Soviets put their missiles?

The reason is because Kennedy knew the real limitations of missile technology, and that short and medium range missiles were the real deal, not the alleged globe-encompassing ICBMs. Kennedy was therefore rightly concerned about Soviet Premier Khrushchev's deployment of nuclear missiles to Cuba.

Despite the alleged existence of ICBM arsenals, the fact is that non-ICBM platforms (e.g. B-52s and submarines) received high priority in the US and other militaries.  A document declassified in 1999 showed that the US had land based nuclear missiles from Greenland to Taiwan in an effort to contain the Soviets during the cold war [2].

The Soviet Union was surrounded by non-ICBM nuclear weapons at all times throughout the cold war
From: United States Secretly Deployed Nuclear Bombs In 27 Countries and Territories During Cold War [2]:
The authors also found that during the peak years in the early 1970s, the United States had more than 7,000 nuclear weapons in NATO countries in Europe, and more than 2,000 on land in the Pacific.
A variety of naval vessels, including aircraft carriers, cruisers, destroyers, frigates and attack submarines, routinely carried another 3,000 nuclear weapons.
Understandably, countries will want to diversify their nuclear weapon delivery platforms.  But why all the emphasis on non-ICBM platforms if space-going ICBMs really were a reality?
...Germany was home for 21 U.S. weapon systems...Guam hosted 20 types and the Japanese island of Okinawa... hosted 19....
I contend that the ICBM (as a vehicle that truly returns from space) plays no part in the present or past nuclear deterrent of all nuclear powers, because they would burn up on reentry.  

France does away with the pretence of ICBMs altogether, and only deploys submarine-launched SLBMs.  All present nuclear weapons delivery platforms centre on medium to long range in-atmosphere missiles launched from land, air or submarines -- none come from outer space.

I have read on pro-Apollo websites that if America faked the moon landing the Soviets would have blown the whistle.  To this I say: why would the Soviets blow the whistle on the Americans when they were lying to their own people just as much about their own space program?

The space race and the spectre of ICBM-led mutually assured destruction was a propaganda tool for the superpower governments that was far more useful than blowing the whistle on their opponent.  And if they did blow the whistle who would believe them anyway?

References: 

[1]  Facing the Heat Barrier: A History of Hypersonics, T. A. Heppenheimer, NASA, 2007. (part 1) (part 2)

[2] United States Secretly Deployed Nuclear Bombs In 27 Countries and Territories During Cold War, (link), a summary of:

History of the Custody and Deployment of Nuclear Weapons: July 1945 through September 1977, Office of the Assistant to the Secretary of Defense (Atomic Energy), 1978.  (link)

[3] Dwight D Eisenhower, Radio and Television Address to the American People on Science in National Security, November 7, 1957. (link)

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