World Missile and Space Launch Vehicle Failures

[R7]

In most rocket failures the detonation is caused by propellant touching hot engine parts, although RP-1 and LOX do form a highly explosive gel when mixed.

In most rocket failures there's hardly any detonations at all, except for the FTS explosive charges. Propellant detonation requires them ending up premixed at ignitable ratio and an energy spike (spark) or deflagration-to-detonation transition (which is easier said than done, just ask PDE-developers).

[Davd]

No, the  cloud is the LH2 condensing water vapor in the air.  The same effect would happen if there was no LOX onboard.

I know that; the hydrogen would still form water vapor from coming into contact with the oxygen in the surrounding atmosphere.

LH2 tank ruptured and LH2 spill down the sides of the vehicle.

Which is pretty obvious. Somehow I was a little bit doubtful of Art's claim that that was the Atlas's LOX spilling.

Also during AC-1's ascent, there's a visible trail of LOX streaming from the Centaur. Not sure if this was intentional or not, but it does remind one of Atlas 3D where the drain valves failed to close at liftoff.

in most rocket failures there's hardly any detonations at all, except for the FTS explosive charges

I did mean deflagration, that was just a poor choice of words. Pay it no heed. Deflagration is what happens if you threw a lit match into a paper cup filled with gasoline. Detonation is what happens inside a car engine (after the gas and air are mixed and ignited).

[Jim]

I know that; the hydrogen would still form water vapor from coming into contact with the oxygen in the surrounding atmosphere.

No, the visible vapor isn't from the combustion of the H2.  It is from the cold of the LH2 condensing atmospheric water into the white visible vapor.  It happens with any cryogenic fluid released into ambient air.

[R7]

Detonation is what happens inside a car engine (after the gas and air are mixed and ignited).

No. (Sorry  Detonation is not supposed to happen in car engines, things are tuned/timed to avoid that. Some times things go wrong and it can happen, it's called the engine knocking, and it destroys the engine quickly.

Please take no offense, it's just me being the pedantic wiserear  Detonation and deflagration are just so well defined that easy to keep them apart. Muddy waters start when using words like "explosion" where definitions become less scientific and more opinion-based. Then again whether things deflagrate rapidly or detonate when they aren't supposed to do either it's usually a bad day anyway...

[Art LeBrun]

No, the  cloud is the LH2 condensing water vapor in the air.  The same effect would happen if there was no LOX onboard.

I know that; the hydrogen would still form water vapor from coming into contact with the oxygen in the surrounding atmosphere.

LH2 tank ruptured and LH2 spill down the sides of the vehicle.

Also during AC-1's ascent, there's a visible trail of LOX streaming from the Centaur. Not sure if this was intentional or not, but it does remind one of Atlas 3D where the drain valves failed to close at liftoff.

I believe the temporary venting was hydrogen. It stopped about 8 seconds prior to the weathershield failure.

[Davd]

I believe the temporary venting was hydrogen. It stopped about 8 seconds prior to the weathershield failure.

Ok makes sense since it's coming from the top of the Centaur where the hydrogen tank is. I now just remembered that this same effect can be seen on Saturn launches.

But enough about AC-1 (at least until Jim posts the accident report he claims to have). Moving onto the next subject in this thread, Atlas 3D which had a nothing short of spectacular failure yet no accident reports have turned up.

Oddly, the official Atlas launch summary lists seem to imply that 3D failed because of the LOX valve not closing at liftoff instead of the (extremely obvious) launcher arm hangup at liftoff.

[Art LeBrun]

Here is a GD/A report I received recently on 3D and 7D. Not scanned from a GD/A document but I assume the wording is accurate.

It seems the B-2 thrust decay accounted for the "lurching" of 3D and not a launcher arm failure. I understand it looks abrupt like a sudden release but this is what I have for the moment. There is a dark stream in the B-2 exhaust which I do not understand. Obviously you need to discount the turbine exhaust just to the outside of B-2.

[Davd]

It seems the B-2 thrust decay accounted for the "lurching" of 3D and not a launcher arm failure.

It would seem that the engine already had some sort of problem that was exacerbated by the LOX spilling and causing an explosion.

There is a dark stream in the B-2 exhaust which I do not understand. Obviously you need to discount the turbine exhaust just to the outside of B-2.

There are a number of things that might cause that. Maybe the fuel/oxidizer mix in the engine was off from its normal value. Also you can seen from the video that there's a fire building up in the thrust section during ascent prior to the explosion @ T+28 seconds. That could have been the result of the liftoff damage or due to whatever problem caused the initial B2 malfunction.

As for 7D, on rewatching the video on Critical Past closely, I see it now. The launcher arm doesn't retract fully at liftoff.

[Art LeBrun]

Atlas Incidents in Images

Image 1 shows Atlas 6D in flight from VAFB January 26, 1960. Note that the two nacelle doors have not closed. No word of effect on flight.

Image 2 shows Atlas-Agena carrying first SAMOS recon satellite aloft on October 11, 1960. Note one Atlas nacelle door is only partially closed. The notable part of the image is the escaping Agena stage attitude control gas from the left side of the interstage. The happened during an umbilical disconnect which tore off part of the plate on the vehicle. Without the attitude control gas the Agena burn was unsuccessful in achieving orbit. There are multiple launch images showing the gas loss.

[Davd]

Atlas Incidents in Images

Image 1 shows Atlas 6D in flight from VAFB January 26, 1960. Note that the two nacelle doors have not closed. No word of effect on flight.

Image 2 shows Atlas-Agena carrying first SAMOS recon satellite aloft on October 11, 1960. Note one Atlas nacelle door is only partially closed. The notable part of the image is the escaping Agena stage attitude control gas from the left side of the interstage. The happened during an umbilical disconnect which tore off part of the plate on the vehicle. Without the attitude control gas the Agena burn was unsuccessful in achieving orbit. There are multiple launch images showing the gas loss.

As 6D and 57D both performed normally during flight, it does not appear that the nacelle doors affected anything.

Also Atlas 131D (Midas 6's booster) suffered liftoff damage similar to 7D however instead of causing pressurization gas to escape, the hydraulic fluid was lost leading to eventual loss of control and RSO destruct.

[kevin-rf]

Nice article on the space review concerning some failures, with root causes.

Launch failures: what’s changed?
http://www.thespacereview.com/article/2256/1

[Art LeBrun]

Nice article on the space review concerning some failures, with root causes.

Launch failures: what’s changed?
http://www.thespacereview.com/article/2256/1

Usually Wayne Eleazer gives dates and missiles with his failure reports but the three Atlas Ds have no such reference. My limited records indicate no such episodes of 3 Atlas D exploding on Cape pads much less the same pad. However, I am intrigued by the separate turbine exhaust duct so I will research that and see if it is visible in photos.

[libra]

Bringing back this oldie... my own little contribution to that topic, now published at The space review.

https://www.thespacereview.com/article/4085/1

Ariane, earthquake, cloth, and the Murphy law. A monument of absurdness - one can only laugh or just shake his head in disbelief.  Such bad luck, for everybody involved.

Yet, it could have been worse

(Samuel L. Jackson memorable -and very unfortunate - quote from Jurassic Park)

[Vahe231991]

I found this video from Youtube showing the first launch of the CZ-3B in February 1996, which ended in failure.