SpaceX And/Or Rocketry In General

Mike Hewson
Mike Hewson
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RE: RE: To me it looks

Quote:
Quote:

To me it looks like the four towers in the background ie. some of those encircling the pad, were mounted with lightning rods ?

Cheers, Mike.

Quite right. We have some fairly serious lightning in this area especially during the summer. Hopefully the towers will attract the lightning rather then the rocket. When the shuttle flew it was encased in a cage with a large white lightning rod on the top. You would not want lightning to be the ignition sequencer. It would not be pretty.


There were also some sheds nearby with lights on inside. I was thinking during the countdown : it'd be a bit late to go back and get the coffee you left on the bench ! :-0

I thought the lady said it was the tanks but here's the real reason for the abort :

Quote:
During the terminal count engineers observed drift on one of the two thrust vector actuators on the second stage that would likely have caused an automatic abort. Engineers called a hold in order to take a closer look. SpaceX is scrubbed for today and we are now targeting launch on Jan. 9th at 5:09am ET.


... so that's the gimballing apparatus to keep the pencil upright on it's end.

Also of interest was the manner in which the flight controllers simply proceeded to put the rocket back in a safe state when the hold was called. I mean it wasn't like anyone was querying ( overtly at least ) the specific reason for the hold : sort that out later. I guess the space-rocketry industries found out a long time ago that 'go-fever' is a bad thing. You have to read it as you see it, and it doesn't matter which attempt it is.

Cheers, Mike.

I have made this letter longer than usual because I lack the time to make it shorter. Blaise Pascal

Chris S
Chris S
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[url]I guess the

[url]I guess the space-rocketry industries found out a long time ago that 'go-fever' is a bad thing.[/url]
I think that there was a bit of that in the past, but you can understand why. It costs millions of dollars to get a vehicle on the launch pad ready to go. A last minute hitch adds to that cost, and keeping it at launch readiness for days, even more. There will be times when people just take calculated risks, at a certain level with just cargo, and another level with human passengers.

Space X is a commercial undertaking, they are not doing it for the fun of it or to boldly go as it were, but to make a profit. It's fledgling days yet for this sort of enterprise, maybe in the future they can take bigger risks and write off 1 in 50 or whatever. Money always talks.

Waiting for Godot & salvation :-)

Why do doctors have to practice?
You'd think they'd have got it right by now

robl
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RE: During the terminal

Quote:
During the terminal count engineers observed drift on one of the two thrust vector actuators on the second stage that would likely have caused an automatic abort. Engineers called a hold in order to take a closer look. SpaceX is scrubbed for today and we are now targeting launch on Jan. 9th at 5:09am ET.
... so that's the gimballing apparatus to keep the pencil upright on it's end.

Its the 1st stage that will be returning to earth and that must "stand on its end". This was a fault in the second stage which will not be returning. But it all has to work.

Chris - agree with your assessment. There is a lot of money riding on these launches. Elon Musk and his team want the big contract so they must demonstrate that they can resupply the ISS as a first step. This means no failures or no failures resulting by bad launch decisions. Yes its costly to have delays like this but a delay followed by a successful launch reinforces SpaceX's ability to deliver.

When I looked out the north window this morning I saw a "vertical con trail". I can't find anything online so it might have been "some other vehicle".

robl
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SpaceX is now scheduled for

SpaceX is now scheduled for Saturday at 0447 Eastern Time.
Every delay seems to trigger an earlier launch time.

Mike Hewson
Mike Hewson
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I have discovered video of

I have discovered video of another prototype test ( no advertising ) evidently in a different season to the other one. I've watched it a good dozen times. The control is exceptional : very fine throttling to transition ever so delicately from upward flight to hover and then descent, the transverse slide across the landscape of about 10m, there is clear control of rotation around the long axis, and upon landing you can see there is barely any movement of the top when it finally settles to rest on the pad. You can also gauge the response of the cows & it has saved them some grass mowing .... :-) :-0

Cheers, Mike.

I have made this letter longer than usual because I lack the time to make it shorter. Blaise Pascal

robl
robl
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Mike, Thanks for that

Mike,

Thanks for that link. I can't stop watching it. It just "magic". Just balancing a rocket on a pencil point is amazing but when you add in throttling back an engine and descending on the pencil point that is a whole new ball game.

I keep looking at the "smoke" coming off of the 4 landing pods. I am amazed that fire does not cut through the body like an acetylene torch.

[edit] let us all be patient with the E@H personnel working the current download/upload problem. Sometimes things happen and barking at them won't help the situation.

Mike Hewson
Mike Hewson
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Yeah it's mesmerising. Each

Yeah it's mesmerising. Each leg is a carbon fibre composite pad held in place by a telescoping suspension strut ( falcon heavy gear shown here ) :

.... with the body of the rocket forming the third side of the triangle. You can see the pad underside glow a dull red from the radiant heat of the main jet flame ( best seen on the right most one when it hovers ), no doubt protecting the suspension strut. So they are indeed burning and it is actually smoke .... :-)

In a launch from a gantry the struts are held in against the rocket body, so they wouldn't get any heat damage at launch ( and you'd want to keep them tucked in during ascent to reduce aerodynamic drag anyway ). So when deployed on the way down they'd be fresh. Probably a new pad set for each launch perhaps ? You could keep the telescoping strut - with testing - across launches I expect. I reckon that is a really simple and clever design with a relatively small number of parts and thus failure modes. They could really concentrate on making the key parts eg. hinges quite rugged. Compare that with a Space Shuttle's landing gear deployment.

Cheers, Mike.

( edit ) Thinking about failure of the struts. Since they are being brought down at sea, if it falls over - or if a strut didn't deploy properly on descent - then you just plop into the ocean. You still have a controllable craft so that could be a rather low velocity splash. Interestingly, since their around-long-axis rotation is so superb one could even dock it into a four-leg cradle which could grasp it just before engine cutoff ....

I have made this letter longer than usual because I lack the time to make it shorter. Blaise Pascal

robl
robl
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Well SpaceX successfully put

Well SpaceX successfully put a cargo delivery pod into orbit for the ISS, but the "ocean" landing was not as successful as hoped. It was a hard landing on the platform. The platform sustained some damage but will be used for future attempts. No video of the landing available due to fox etc.

They tracked the launch with cameras focused on the 1st stage engines. Watching the launch I was reminded of the "little engine that could". It seemed to me to be a very slow ascent but it was dark at launch time so it might have been an illusion.

[EDIT] When viewing the video again it looks as if something (a landing pad) is extended away from the body. Can't be sure though.

Mike Hewson
Mike Hewson
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RE: When viewing the video

Quote:
When viewing the video again it looks as if something (a landing pad) is extended away from the body. Can't be sure though.


Funny that you ought mention the pads. I have some thoughts because it also didn't look right to me either.

At about 50 seconds into ascent, when there is still direct ground shot footage, I thought the one on the right of view wasn't the same as that on the left :

ie. the gap on the right stem of the 'M' here. In fact at T + 20 seconds you see this :

ie. flame to that side of the base and issuing from above the level of the rocket bells and so where said struts are. I think that right side pad is well alight. This is the view just 5 seconds after launch :

.... so the 'M' is intact. NB the flame billowing up the right side is deflection off the 'strongback' gantry.

Hypothesis : it takes at least a few seconds to throw enough heat on it, the roiling flame at ignition plus radiated reflection off the ground. It catches fire for a short while but this 'blows out' the visible flame with increasing speed. But that doesn't mean there isn't ongoing damage, until you exit the atmosphere. There is a 'gutter' within the carbon composite ( see two posts ago ), the entry of which faces towards the flight direction, which could easily funnel air well into the interior. Burning could continue there out of obvious view.

Thoughts ?

Cheers, Mike.

( edit ) The radiant heat in this scenario is immense. At such close proximity temperatures can increase from ambient to several thousand degrees ( Celsius, Kelvin, Fahrenheit, Rankin .... whatever you like ) far quicker than it takes you to read this sentence.

I have made this letter longer than usual because I lack the time to make it shorter. Blaise Pascal

robl
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Mike, I agree it did not

Mike,

I agree it did not look right/clean. Its my "feeling" that they had some "luck" enter into the launch sequence. I agree the "pad on the right" looked to me like is was "hanging out" and not neatly tucked in. If we are both correct in our evaluation of the lift then maybe this was a cause for the not so successful recovery. You can however measure success in many ways, i.e., the mere fact that it did make a vertical descent and make contact with the pad. While not a "pretty contact" it does boast well for their guidance system.

There has been no discussion about the pads not being properly configured during launch. If something was not right I feel certain that someone would have pointed it out. No, not the news anchors but someone in the "space community".

Guess we will have to wait and see.

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