# Rocket explosion compared to kT of TNT; has one ever knocked something over at a distance?

The energy equivalent of 1 gram of TNT is about 1 kcal or large Calorie. For reference, 1 gram of carbohydrates gives us almost 4 Calories of energy (if we are lucky enough to use it and not store it).

So upon detonation or complete combustion with oxygen:

1 kT of    yields    Joules
--------             -------
TNT                  4.2E+12
carbs                1.7E+13
Kerosene             4.6E+13
Methane              5.5E+13
Hydrogen             1.4E+14


If we naively treat a catastrophic rocket explosion (on the launchpad or during an unlikely mishap where it comes crashing down soon after launch on the equivalent of the Pillars of Baikonur), then rocket fuel has 100 to 300 times the energetic "yield" of TNT.

But rockets are not exactly proper explosive devices despite popular analogies in space lore (nor are they candles to be lit) and their explosions are sometimes called "fast fires" (1, 2, 3, 4, 5).

So even though the potential energy yield of rocket fuel is orders of magnitude larger than TNT, it's explosive yield, say in equivalent shock wave energy, might be far less.

Question: Have there been any quantitative estimates of the explosive energy released in a rocket explosion, separate from the total energy released as heat? Has a rocket explosion every knocked something down at a distance, or blown out windows for example?

• . Blast waves resulting from the detonation of strong explosives (e.g., TNT) exhibit close to ideal wave behavior due to the relatively small amount of explosives and the quick release of energy associated with a rapid chemical reaction. hal.archives-ouvertes.fr/hal-00629253/document – A. Rumlin Oct 20 '19 at 5:14
• Note a problem with your numbers: TNT includes it's own oxidizer, the rest of the numbers assume atmospheric oxygen and thus a total reaction mass well above the fuel being burnt. I do recall a broken window in the video of that Proton crash out of Russia. In general, though, there isn't much of anything within the blast range of a rocket on the pad and western rockets have range safety packages installed--they don't go boom on the ground anywhere else. Thus the only examples you're likely to find are from Russia or China. – Loren Pechtel Oct 20 '19 at 6:37
• Related: TNT equivalent for the shuttle External Tank: space.stackexchange.com/a/37074/6944 – Organic Marble Oct 20 '19 at 12:06
• @OrganicMarble Okay, skimmed PHASE II; pages 3-13 through 3-16 (pdf pages 43 to 46) which discusses "project PYRO" which I'm definitely going to try to track down (as well as references 4 to 7) – uhoh Oct 20 '19 at 16:33
• The 2014 Antares Explosion is said to have "knocked two spectators off the bed of their pickup truck and another off her dock. The blast broke windows and imploded doors in buildings close to the launch site." (Source). Does that qualify? – Polygnome Oct 20 '19 at 18:53

National Geographic reports that the 2014 Antares explosion carrying a Cygnus v4 for the Cygnus CRS Orb-3 mission "knocked two spectators off the bed of their pickup truck and another off her dock. The blast broke windows and imploded doors in buildings close to the launch site", which both shows that something did indeed knocked over and windows got blown out.

Furthermore, reportedly "there [was] some evidence of damage to piping that runs between the fuel and commodity storage vessels and the launch mount, but no evidence of significant damage to either the storage vessels or launch mount".

On a side note, in this interview, Brian Mosdell talks about the Delta II Explosion on January 17th, 1997 and how he experienced the blast wave hitting the bunker, as well as how his car was melted by falling debris.

• the car-melting incident was a Delta II at KSC, a solid booster exploded and burning solid propellant rained down spectacularly onto, among other places, a full parking lot. google.com/url?sa=t&source=web&rct=j&url=https://… – Organic Marble Oct 21 '19 at 9:55
• @OrganicMarble Thanks, that was the incident I was looking for! – Polygnome Oct 21 '19 at 10:10
• @OrganicMarble I remember that one...because that Delta II exploded the day my daughter was born, and we were watching it happen live on TV in the hospital! – Ogre Psalm33 Oct 21 '19 at 12:43
• @OrganicMarble That sounds epic, the 1812 overture is a great piece of music :D – Polygnome Oct 21 '19 at 17:04
• Very low resolution but here it is: youtube.com/watch?v=jKVUHhHKe1c Good footage of melted cars at the end. – Organic Marble Oct 21 '19 at 17:17

During the moon race, a soviet N-1 rocket exploded seconds after liftoff.

This is ranked as one of the largest conventional explosions with an approximate yield of 1 kt of TNT.

Upon impact of the base of the N1 with the pad, the vehicle exploded, destroying launch pad 110 east, which would take over 18 months to repair.

[...]

At T+23 seconds the base of the N1 hit the launch pad, and 2500 tonnes of liquid oxygen and kerosene exploded, illuminating the steppe for dozens of kilometres. At Leninsk, 35 km away, an enormous bright light burst in the north, and the residents knew the unthinkable had happened. All of the windows were blown out of the apartment buildings at area 113, and at the back-up N1 launch complex 6 km away.

Encyclopedia Astronautica, N1 5L launch, 1969-07-03

The Intelsat 708 accident did a significant amount of damage to a village in China.

On February 15, 1996, the Long March 3B rocket failed during launch, veering off course immediately after liftoff and crashing into a village near the launch site (probably Mayelin Village).1 An enormous explosion destroyed most of the rocket and killed an unknown number of inhabitants.[3]

The nature and extent of the damage remain a subject of dispute. ...When reporters were being taken away from the site, they found that most buildings had sustained serious damage or had been flattened completely.[4]

There’s a controversy about the number of casualties, but it seems clear there was a large damage area.

Those on top of the building descended a ladder to the lower roof, and from there scrambled into the building, as the violent shock wave rioted over the facility. A large glass-enclosed entrance shattered into thousands of fragments.