There seems to have been an anomaly.

[5.56NATO]

https://www.youtube.com/watch?v=_BgJEXQkjNQ

I wonder how many of these can take place before their insurance stops paying?

[Schuetzenman]

Wow, that's going to ruin somebody's day.

[alismith]

"Liberty Mutual won't raise your rates due to your first accident."

[Helen Keller]

what are these using as fuel???





this looks like those old german rocket films.

[imanaknut]

Initial reports state an upper stage oxygen tank let go.

[Krupski]

what are these using as fuel???





this looks like those old german rocket films.



RP-1 (refined kerosens) is the fuel, LOX (liquid oxygen) is the oxidizer.

BTW, the German rockets (like the A4/V2) used a mixture of water and ethanol (basically vodka!) as fuel, and LOX as oxidizer.

[Krupski]

Initial reports state an upper stage oxygen tank let go.



I watched the video over and over. There is a VERY bright flash near the top of the second stage (right below the payload fairing) that only lasts for 2 video frames, then all hell breaks loose.

I wonder if the PDS (Propellant Dispersion System) (otherwise known as the "destruct" system) didn't get set off somehow.

The destruct system usually uses linear shaped charges on the outside of propellant tanks, the idea being that if there's a fatal problem with the rocket, the tanks can be torn apart and the fuel harmlessly mixed and burned (exploded) up in the air rather than letting a bomb crash to the ground.

The second stage was fuelled (at least it had LOX, since it can be seen venting from both stages), but normally the second stage isn't fully pressurized until the stage is ready to be started. If the tank did let go, then maybe a LOX vent valve was accidentally closed, allowing pressure to build up and rupture the tank.

But, at the time of the accident, IF only LOX were vented, all you would see would be a large white cloud. Any fire would start later when the oxygen reached something that was already burning and accelerated that burning.

I've seen a lot of films of tank failures, and usually they just billow out "harmlessly" for a few seconds before the propellants mix, get ignited by something, then the flames destroy the rest of the booster.

The one yesterday looks VERY strange... my guess is that the destruct system fired accidentally (or purposely... sabotage?)

[ltorlo64]

"Liberty Mutual won't raise your rates due to your first accident."

Hahahahahahahaha!

[Full Otto]

Saw that on the news then they showed an earlier failure from 2015
I think this is it
https://www.youtube.com/watch?v=cqQ6jD52r_Q

It was already airborne but looks like the trouble started at the same spot

[l921428x]

I watched the video over and over. There is a VERY bright flash near the top of the second stage (right below the payload fairing) that only lasts for 2 video frames, then all hell breaks loose.

I wonder if the PDS (Propellant Dispersion System) (otherwise known as the "destruct" system) didn't get set off somehow.

The destruct system usually uses linear shaped charges on the outside of propellant tanks, the idea being that if there's a fatal problem with the rocket, the tanks can be torn apart and the fuel harmlessly mixed and burned (exploded) up in the air rather than letting a bomb crash to the ground.

The second stage was fuelled (at least it had LOX, since it can be seen venting from both stages), but normally the second stage isn't fully pressurized until the stage is ready to be started. If the tank did let go, then maybe a LOX vent valve was accidentally closed, allowing pressure to build up and rupture the tank.

But, at the time of the accident, IF only LOX were vented, all you would see would be a large white cloud. Any fire would start later when the oxygen reached something that was already burning and accelerated that burning.

I've seen a lot of films of tank failures, and usually they just billow out "harmlessly" for a few seconds before the propellants mix, get ignited by something, then the flames destroy the rest of the booster.

The one yesterday looks VERY strange... my guess is that the destruct system fired accidentally (or purposely... sabotage?)

What i found strange was the continued explosions and burning after the initial blast.
Maybe it's just me but it seemed unusual that the gantry area flared back to the intensity
it did(3:36), maybe a bad er shutdown valve.

[JTHunter]

Saw that on the news then they showed an earlier failure from 2015
I think this is it
https://www.youtube.com/watch?v=cqQ6jD52r_Q

It was already airborne but looks like the trouble started at the same spot

Agreed.
What caught my eye was the enormous white cloud that appeared near the front of the rocket. If - IF - that was the LOX tank letting go, the extra O2 getting into the flare of the main engines could have caused them to burn hotter, melting the nozzles and adding a torsional twist that stressed the already damaged airframe even more. Remember, 2-3 seconds before the cloud appeared, the video said something about having reached "maximum aerodynamic pressure".

[Krupski]

Agreed.
What caught my eye was the enormous white cloud that appeared near the front of the rocket. If - IF - that was the LOX tank letting go, the extra O2 getting into the flare of the main engines could have caused them to burn hotter, melting the nozzles and adding a torsional twist that stressed the already damaged airframe even more. Remember, 2-3 seconds before the cloud appeared, the video said something about having reached "maximum aerodynamic pressure".



Here's a slo-mo GIF of the explosion (one second per frame - watch for 3-2-1 in the upper left corner):


(click pic to view)
http://www.hobbytent.com/other/files/space-x-thumb.jpg (http://www.hobbytent.com/other/files/animation3.gif)


Doesn't look like a ruptured tank to me. The tank ruptures AFTER the bright flash!

If the LOX tank ruptured by itself, then what ignited the explosion?

[Krupski]

Agreed.
What caught my eye was the enormous white cloud that appeared near the front of the rocket. If - IF - that was the LOX tank letting go, the extra O2 getting into the flare of the main engines could have caused them to burn hotter, melting the nozzles and adding a torsional twist that stressed the already damaged airframe even more. Remember, 2-3 seconds before the cloud appeared, the video said something about having reached "maximum aerodynamic pressure".



The last one (that failed after launch) had passed through Max-Q before it exploded (about 50 seconds after). And, notice that when the second stage LOX tank failed, it spewed out clouds of oxygen which did NOT burn with anything else.




https://youtu.be/PuNymhcTtSQ



By the way, Max-Q is, if you can picture it, the rocket starts out on the ground (maximum air density, zero velocity). As it climbs and goes faster, the aerodynamic loads on the vehicle increase, but at the same time it's getting higher and higher so that atmospheric pressure decreases (air is getting thinner).

The rocket reaches a point where the speed creates maximum air loading before the atmosphere begins to thin out more as it climbs.

This peak pressure is called "maximum aerodynamic pressure" and aerodynamic pressure is designated as "Q" in such calculations, therefore this point is called "Max-Q".

[ltorlo64]

Cool. Thanks for the explanation.

[O.S.O.K.]

I don't understand why they don't use a standard jet system to gain altitude and then employ a booster to achieve escape velocity. And then use the same system for controlled re-entry and landing....

And further, I would have expected that we would have developed a nuclear propulsion system of some type by now - for after the vehicle is in orbit...

But I'm a salesman with a business degree. So what do I know...

[5.56NATO]

The weight issue most likely. They need the lightest source of thrust that can be devised to put something in orbit or beyond. Also, for nuclear flying vehicles, look into the US nuclear powered bomber.

[JTHunter]

Saw that on the news then they showed an earlier failure from 2015
I think this is it
https://www.youtube.com/watch?v=cqQ6jD52r_Q

It was already airborne but looks like the trouble started at the same spot

Krupski - I was talking about Otto's link about the O2 tank letting go, not the launch from the OP.
Sorry for the confusion.

[Krupski]

I don't understand why they don't use a standard jet system to gain altitude and then employ a booster to achieve escape velocity. And then use the same system for controlled re-entry and landing....

And further, I would have expected that we would have developed a nuclear propulsion system of some type by now - for after the vehicle is in orbit...

But I'm a salesman with a business degree. So what do I know...

Two reasons why jet engines are not used:

(1) The thrust to weight ratio of a rocket engine is MUCH higher than any jet engine. Any advantage derived from using outside air as an oxidizer would be outweighed (no pun intended) by the mass of the jet engine.

(2) The rocket climbs up into thin, then non-existent atmosphere rather quickly. Since a jet engine needs external oxygen (air) to work, it would become useless after a few minutes of flight.

Concerning nuclear engines... those were invented and tested in the 1950's-1960's and they worked rather well (performance wise). But, they require an amazingly powerful reactor to generate the hundreds of megawatts of heat required to heat the propellant gas (usually hydrogen) to working temperature AS FAST AS IT FLOWS THROUGH. (Imagine trying to put enough heat into a garden hose sized stream of water with the water flowing right through and heating it fast enough so that it's boiling as it leaves the hose)... TREMENDOUS amount of heat needed.

Since the propellant is carrying the heat away from the reactor, it's obvious that the reactor needs a fast acting control loop to maintain the proper power output if the propellant flow varies (or stops). If the flow stopped, the reactor, no longer being cooled, would overheat and melt in seconds.

Lastly, the reactor is heavy and produces hideous amounts of lethal hard radiation which would kill the crew of a manned spacecraft and/or destroy electronics without shielding. And, there's no way to run it on the ground (as in using it for a launch) because the launch pad area would be uninhabitable for months due to the radioactive exhaust. It would have to be an upper stage engine that runs in space only. Too dangerous to use is the reason they're not used.

See this for more info on nuclear rocket engines: https://en.wikipedia.org/wiki/NERVA

[FunkyPertwee]

Hopefully we can get a space elevator for putting things in orbit, use chemical propulsion to get to the moon or out into space, and use nuclear rockets for launching from space or the moon.

[sevlex]

Here's a slo-mo GIF of the explosion (one second per frame - watch for 3-2-1 in the upper left corner):


(click pic to view)
http://www.hobbytent.com/other/files/space-x-thumb.jpg (http://www.hobbytent.com/other/files/animation3.gif)


Doesn't look like a ruptured tank to me. The tank ruptures AFTER the bright flash!

If the LOX tank ruptured by itself, then what ignited the explosion?

Interesting to see an object fly by at the exact moment of detonation.

:think:

[Hobe Sound AK]

Just throwing this out there. Is it Possible NASA is afraid they are going to be passed over big Time, as their Projected Date of Landing on Mars was 1996, and 20 Years later they are still a Stumbling and Bumbling Agency, and they sabotaged the Rocket? Just guessing but I think NASA may feel it is doomed if a Private Company Lands on Mars! Paul

[Krupski]

Interesting to see an object fly by at the exact moment of detonation.

:think:



Bird. A very scared bird.

[Krupski]

Just throwing this out there. Is it Possible NASA is afraid they are going to be passed over big Time, as their Projected Date of Landing on Mars was 1996, and 20 Years later they are still a Stumbling and Bumbling Agency, and they sabotaged the Rocket? Just guessing but I think NASA may feel it is doomed if a Private Company Lands on Mars! Paul



NASA is not a "stumbling and bumbling" agency. They are hampered by 0bongo tearing their budget to shreds.

As far as landing on Mars, it's already been done many times.

Unless you mean a MANNED landing (which I assume would include a safe return to earth?)

If so, fuggetaboutit. With our current chemical propulsion, it's not possible to get to Mars and back safely (or in a reasonable amount of time).

[Hobe Sound AK]

That what I meant! Manned Missions to Mars! and Back, Now they are saying 2060! come-on! Yes it may take 3 Years there and 3 Back, But Mars is the only Planet that We would live long enough to see before we Died. Past Mars is a long long way off, at least a Century to get past Pluto. Paul

[FunkyPertwee]

That what I meant! Manned Missions to Mars! and Back, Now they are saying 2060! come-on! Yes it may take 3 Years there and 3 Back, But Mars is the only Planet that We would live long enough to see before we Died. Past Mars is a long long way off, at least a Century to get past Pluto. Paul


There are probably plenty of similar enough ice comets between here and Pluto that would be just as "nice" to visit.

[Krupski]

That what I meant! Manned Missions to Mars! and Back, Now they are saying 2060! come-on! Yes it may take 3 Years there and 3 Back, But Mars is the only Planet that We would live long enough to see before we Died. Past Mars is a long long way off, at least a Century to get past Pluto. Paul



The reason there will never be a manned mission to Mars (which includes a safe return) using current propulsion technology is MASS RATIO.

Mass ratio is the mass of an empty rocket versus a fuelled and stocked (with life support) rocket's mass.

The problem is this: Want to carry more "stuff" to space? It's mass dictates that more fuel is needed (and/or larger engines). This makes the rocket weigh more. Since the rocket weighs more, it needs even more fuel. More fuel adds to the weight of the rocket, requiring more fuel and/or larger engines and/or a stronger, larger structure which, in turn, requires more fuel.............(this goes on forever).

Now, look at the Apollo moon missions. The destination was the moon, only about 240,000 miles away, and orbiting the earth (that is, aside from orbital eccentricity, the distance between earth and moon remains constant).

The total, fully fuelled vehicle (Saturn V) had a mass of about 6.8 million pounds (the MAJORITY of that being propellant). The mass of the Command module (the conical part that came back from the moon) had a mass of 12250 pounds. The RATIO of mass needed to GET to the moon versus the mass that CAME BACK was 0.18 percent!

And, that's for a short trip (about 4.5 days to get there, and 4.5 days to come back). Also, the gravity of the moon is only 1.622 m/s^2 compared to earth's 9.807 m/s^2 (i.e about 1/6 the gravity of earth).

Therefore, to land on the moon with it's low gravity didn't require much thrust or propellant (or lander strength) and even less thrust to take off again (leaving more than 1/2 of it's mass behind as the descent stage).

With the small gravity of the moon and the short distance to it (and the fact that it stays with us), it took a ginormous rocket, the bleeding edge of our technology, just to barely get there and back.

Now, compare that to Mars which has a bit over 1/3 of the earth's gravity (or twice that of the moon), PLUS the fact that the distance between earth and Mars VARIES between 35 million miles and 250 million miles.

This means that the launch time for a Mars mission has to be timed properly to minimize the travel distance. Likewise, returning from Mars again requires that same timing.

This results in about 22 to 25 months flight time required to get there, then STAYING there for about 25 months (until the next transfer orbit alignment), then another 22 to 25 months to get back.

The mission would require the majority of the total propellant mass to leave earth and get into a transfer orbit (a huge elliptical orbit who's apoapsis intersects Mars orbit).

Then, propellant to slow down and enter orbit around Mars, then more propellant to land there, then more to liftoff again into Mars orbit, then a final burn to raise the orbit's apoapsis to intersect Earth's orbit, then finally an atmospheric entry culminating in a parachute / ocean landing.

If we BARELY made it to the moon and back with Apollo, how in hell do you think it can be done for Mars (with our CURRENT technology of course)?

If we invent radically new propulsion technology, THEN a mission to Mars will be possible. It's also possible that the new technology will be so far ahead of what we have now that "merely" going to Mars won't be worth the trouble.

But, that's in the future. Never happening now or any time soon.

However, if fantasies of a Mars mission get NASA more funding then I'm all for it!

[O.S.O.K.]

Roger, please send plans for Ion propulsion to NASA so they can get on with it...

I'd suggest the Warp drive plans but I don't think they're ready for that!