4 ms·

Little Boy, with an effective yield of ~15kt, had a 5psi radius of 3500m. The "only" in my comment was a response to the assertion that it required "multi-mega

Little Boy, with an effective yield of ~15kt, had a 5psi radius of 3500m. The "only" in my comment was a response to the assertion that it required "multi-megaton" warheads to make ICBMs practical.

CapitalistCartr 10y ago
We never had many megaton weapons. Two megaton was about the limit, and most weapons were under 500 kilotons. Accuracy is better. Huge bombs was a dick-waving contest, and after Tsar Bomba, we gave up that game and went for sophistication.
- mikeash 10y ago
  The W38 used on Atlas and Titan 1 was 3.75 megatons. If we consider bomber weapons, the B41 was a 25 megaton weapon with about 500 built. The B53/W53 was a 9 megaton bomb for both bombers and missiles, with around 100 built. There are more beyond 2 megatons; these are examples, not a comprehensive list. Huge bombs weren't a dick-waving contest, they were partly to maximize the value of an ICBM carrying one warhead, and partly to mitigate inaccuracy. As MIRV became practical and accuracy increased, yields decreased on both sides of the Cold War, because smaller bombs are just plain more efficient if you can put them where they need to go.
- arethuza 10y ago
  The Soviets and then the Russians deployed variants of the SS-18 with very large warheads (20-25Mt) until fairly recently - either for EMP purposes or to attack Cheyenne Mountain, Raven Rock Mountain etc. https://en.wikipedia.org/wiki/R-36_(missile) https://en.wikipedia.org/wiki/R-36_(missile)
- hga 10y ago
  They're useful for very hard targets, like dropping two 20Mt or so at the same time at each end of the access tunnel for the Cheyenne Mountain Complex (https://en.wikipedia.org/wiki/Cheyenne_Mountain_Complex https://en.wikipedia.org/wiki/Cheyenne_Mountain_Complex). Otherwise, at something in the 1 Mt plus or minus level, I forget, a lot of the energy is wasted by being thermally re-radiated out into space.
mikeash 10y ago
Are you sure about that? The NUKEMAP[0] shows a 15kt airburst with a 5psi radius of 1.67km. And "most residential buildings collapse" isn't going to be very useful against military targets, there I think you're looking more at the 20psi level, which is only 340 meters. [0] http://nuclearsecrecy.com/nukemap/ http://nuclearsecrecy.com/nukemap/
- vonmoltke 10y ago
  It looks like I was going off bad information. I ran the numbers (as best I could) in the Nuclear Bomb Effects Computer[1] and I'm getting a radius of about 1mi. The Wiki author claims to have run the same calculation with the same computer and come up with 2.2mi, though he later contradicts himself by saying the 5 psi contour at Hiroshima was at 1.1mi. [1] http://www.fourmilab.ch/cgi-bin/Bombcalc?yield=15&yunit=1&range=1&runit=1&rotate=0&imsize=800 http://www.fourmilab.ch/cgi-bin/Bombcalc?yield=15&yunit=1&ra...
  - mikeash 10y ago
    1 mile fits with the NUKEMAP number of 1.67km, so it seems reasonable to go with that unless there's something better. 2.2 versus 1.1 smells like mixing up radius with diameter, but I could be completely wrong about that.

Little Boy, with an effective yield of ~15kt, had a 5psi radius of 3500m. The "only" in my comment was a response to the assertion that it required "multi-megaton" warheads to make ICBMs practical.

CapitalistCartr 10y ago

We never had many megaton weapons. Two megaton was about the limit, and most weapons were under 500 kilotons. Accuracy is better. Huge bombs was a dick-waving contest, and after Tsar Bomba, we gave up that game and went for sophistication.

mikeash 10y ago
The W38 used on Atlas and Titan 1 was 3.75 megatons. If we consider bomber weapons, the B41 was a 25 megaton weapon with about 500 built. The B53/W53 was a 9 megaton bomb for both bombers and missiles, with around 100 built. There are more beyond 2 megatons; these are examples, not a comprehensive list. Huge bombs weren't a dick-waving contest, they were partly to maximize the value of an ICBM carrying one warhead, and partly to mitigate inaccuracy. As MIRV became practical and accuracy increased, yields decreased on both sides of the Cold War, because smaller bombs are just plain more efficient if you can put them where they need to go.
arethuza 10y ago
The Soviets and then the Russians deployed variants of the SS-18 with very large warheads (20-25Mt) until fairly recently - either for EMP purposes or to attack Cheyenne Mountain, Raven Rock Mountain etc. https://en.wikipedia.org/wiki/R-36_(missile) https://en.wikipedia.org/wiki/R-36_(missile)
hga 10y ago
They're useful for very hard targets, like dropping two 20Mt or so at the same time at each end of the access tunnel for the Cheyenne Mountain Complex (https://en.wikipedia.org/wiki/Cheyenne_Mountain_Complex https://en.wikipedia.org/wiki/Cheyenne_Mountain_Complex). Otherwise, at something in the 1 Mt plus or minus level, I forget, a lot of the energy is wasted by being thermally re-radiated out into space.

mikeash 10y ago

Are you sure about that? The NUKEMAP[0] shows a 15kt airburst with a 5psi radius of 1.67km. And "most residential buildings collapse" isn't going to be very useful against military targets, there I think you're looking more at the 20psi level, which is only 340 meters. [0] http://nuclearsecrecy.com/nukemap/ http://nuclearsecrecy.com/nukemap/

vonmoltke 10y ago
It looks like I was going off bad information. I ran the numbers (as best I could) in the Nuclear Bomb Effects Computer[1] and I'm getting a radius of about 1mi. The Wiki author claims to have run the same calculation with the same computer and come up with 2.2mi, though he later contradicts himself by saying the 5 psi contour at Hiroshima was at 1.1mi. [1] http://www.fourmilab.ch/cgi-bin/Bombcalc?yield=15&yunit=1&range=1&runit=1&rotate=0&imsize=800 http://www.fourmilab.ch/cgi-bin/Bombcalc?yield=15&yunit=1&ra...
- mikeash 10y ago
  1 mile fits with the NUKEMAP number of 1.67km, so it seems reasonable to go with that unless there's something better. 2.2 versus 1.1 smells like mixing up radius with diameter, but I could be completely wrong about that.