Author Topic: SpaceX Texas launch site Discussion and Updates - Thread 9  (Read 149458 times)

Offline marsbase

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Re: SpaceX Texas launch site Discussion and Updates - Thread 9
« Reply #420 on: 01/11/2019 09:03 pm »
I'm sure an expert can articulate that better.
I'd be happy to try.   
surface:thickness:concrete :: AC in NC:NSF:SpaceX  :) 
How's that?
« Last Edit: 01/11/2019 09:04 pm by marsbase »

Online ajmarco

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Re: SpaceX Texas launch site Discussion and Updates - Thread 9
« Reply #421 on: 01/11/2019 09:42 pm »
How long did it take for the other concrete cakes pads of SpaceX to be layed down and cured to the useable state? Given that the concrete should not be super thick, less than two weeks would be my guess?

I don't know the answer to that specific question but when the issue of concrete cure came up recently, I did some sluething.

Depending on whether they need an Ultra-High Compression Strength Concrete they might not need a full standard 30-day-ish cure.  Concrete specifications can be created to deliver a target compression strength at 1-, 3-, 5-, 7-, 14-, 28-days or whatever is required.  Only exception would be if they were at the absolute limit (or close) of what concrete mixes can deliver.

As an aside, IIRC the thickness isn't as important to cure time as it might seem on the surface.  It does play into a concrete cure due to temperatures and such but in general, cure is a factor of chemical process that occur within the pour mostly unrelated to thickness.  I'm sure an expert can articulate that better.

Most concrete mixes are of a 28-day cure. However, there are admixtures that can change that number depending or the requirements of the pad. The cure time is also stated for full strength but most concrete mixes have a logarithmic curve for strength v. time. So on a 28-day mix lets say it would reach 75% strength in 7-days.

I am sure that the strength of the concrete pad is important but I wonder if the dryness is not equal or more

so? Humidity at the coast amounts to dampness which leads to steam which makes exploding concrete!

If the hopper is going to fly by mid-February, I don't believe it will be flying off of concrete.  From the latest image  Nomad posted of the launch site preparation there appears to be quite a bit of red clay present. 

I talked to someone who worked on the DC-X project and he mentioned they flew off of a clay foundation in White Sands.   My hunch is the site maybe much closer to being ready than we expect.  I would think we should see ground support equipment turning up somewhere on site at any moment.  If it happens to be mobile on larger pneumatic tires, I would guess the site is basically done.     
« Last Edit: 01/11/2019 10:12 pm by VerticalEnvelope »

Offline Lars-J

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Re: SpaceX Texas launch site Discussion and Updates - Thread 9
« Reply #424 on: 01/11/2019 10:03 pm »
If the hopper is going to fly by mid-February, I don't believe it will be flying off of concrete.  From the latest image  Nomad posted of the launch site preparation there appears to be quite a bit of red clay present. 

I talked to someone who worked on the DS-X project and he mentioned they flew off of a clay foundation in White Sands.   My hunch is the site maybe much closer to being ready than we expect.  I would think we should see ground support equipment turning up somewhere on site at any moment.  If it happens to be mobile on larger pneumatic tires, I would guess the site is basically done.     

IMO there is not a chance in hell that they will launch the hopper from a dirt surface. It will hop from a concrete pad, although it is possible they will add additional plating on top of the concrete.

Will they experiment with dirt surface hops later? Possibly but not soon. But launching off it would be increasing risk for early test significantly.

EDIT: They seem to have started pouring concrete for the pad: https://forum.nasaspaceflight.com/index.php?topic=47120.msg1900041#msg1900041
« Last Edit: 01/11/2019 10:08 pm by Lars-J »

Offline SPITexas

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Re: SpaceX Texas launch site Discussion and Updates - Thread 9
« Reply #425 on: 01/11/2019 10:37 pm »
Reports coming in from a Twitter user Austin Barnard says spacex will soon put in fuel tank and reports of 12 concrete trucks at the pad recently today.  So things are moving fast.

Offline Elmar Moelzer

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Re: SpaceX Texas launch site Discussion and Updates - Thread 9
« Reply #426 on: 01/11/2019 11:52 pm »
Why couldn't they just use a bunch of those ready made concrete slabs that are used on roads and driveways? That should be really quick.

Offline Nomadd

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Re: SpaceX Texas launch site Discussion and Updates - Thread 9
« Reply #427 on: 01/12/2019 01:45 am »
 I'm not sure if I'd take the word of a Border Patrol agent for much. They've told me quite a few things about the project, every one wrong.
Those who danced were thought to be quite insane by those who couldn't hear the music.

Offline Scylla

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Offline freddo411

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Re: SpaceX Texas launch site Discussion and Updates - Thread 9
« Reply #429 on: 01/12/2019 02:24 am »
If the hopper is going to fly by mid-February, I don't believe it will be flying off of concrete.  From the latest image  Nomad posted of the launch site preparation there appears to be quite a bit of red clay present. 

I talked to someone who worked on the DC-X project and he mentioned they flew off of a clay foundation in White Sands.   My hunch is the site maybe much closer to being ready than we expect.  I would think we should see ground support equipment turning up somewhere on site at any moment.  If it happens to be mobile on larger pneumatic tires, I would guess the site is basically done.     

Welcome to NSF.   Glad to have you here.

Offline freddo411

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Re: SpaceX Texas launch site Discussion and Updates - Thread 9
« Reply #430 on: 01/12/2019 02:25 am »
I'm not sure if I'd take the word of a Border Patrol agent for much. They've told me quite a few things about the project, every one wrong.

Did he tell you the water tower was going to be a rocket ship?

Offline Wolfram66

https://twitter.com/austinbarnard45/status/1083886957053251584

Is it my imagination or are there mismatched dual bell geometries/sizes on the frankenRaptors? Or is it a trick of shadows and perspective

Offline tyrred

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Re: SpaceX Texas launch site Discussion and Updates - Thread 9
« Reply #432 on: 01/12/2019 08:50 am »
https://twitter.com/austinbarnard45/status/1083886957053251584

Is it my imagination or are there mismatched dual bell geometries/sizes on the frankenRaptors? Or is it a trick of shadows and perspective

The bell covers have been throwing everybody off.  It's not just you.

Offline Zed_Noir

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Re: SpaceX Texas launch site Discussion and Updates - Thread 9
« Reply #433 on: 01/13/2019 06:10 am »
Since it is about 40 meters tall. Do anyone know if the hopper is visible from South Padre Island?

Offline Nomadd

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Re: SpaceX Texas launch site Discussion and Updates - Thread 9
« Reply #434 on: 01/13/2019 03:01 pm »
I am sure that the strength of the concrete pad is important but I wonder if the dryness is not equal or more

so? Humidity at the coast amounts to dampness which leads to steam which makes exploding concrete!
I hadn't thought of that. I do know of instances, like the Chunnel, where concrete has cured before drying all the way and it wound up retaining moisture that caused a lot of grief during a fire. It must be an interesting balance when it's going to be exposed to a million and a half pounds of very hot exhaust. People keep equating this thing to Grasshopper, but three of the newer Raptors will be a whole different level of punishment than one early model Merlin.
Those who danced were thought to be quite insane by those who couldn't hear the music.

Offline Nomadd

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Re: SpaceX Texas launch site Discussion and Updates - Thread 9
« Reply #435 on: 01/13/2019 03:02 pm »
Since it is about 40 meters tall. Do anyone know if the hopper is visible from South Padre Island?
I hope you're happy. Now I have to go to SPI to look. Guess I might as well stop at Kelly's pub while I'm there.
Those who danced were thought to be quite insane by those who couldn't hear the music.

Offline Btx

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Re: SpaceX Texas launch site Discussion and Updates - Thread 9
« Reply #436 on: 01/13/2019 04:13 pm »
Since it is about 40 meters tall. Do anyone know if the hopper is visible from South Padre Island?

Very much so. Here's a link to the RGV forum that I follow. Someone took a picture from the Jetties of SPI:
https://www.tapatalk.com/groups/rgvfr/spacex-in-brownsville-t1680-s210.html

Offline Llian Rhydderch

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Re: SpaceX Texas launch site Discussion and Updates - Thread 9
« Reply #437 on: 01/13/2019 04:18 pm »
Since it is about 40 meters tall. Do anyone know if the hopper is visible from South Padre Island?

Very much so. Here's a link to the RGV forum that I follow. Someone took a picture from the Jetties of SPI:
https://www.tapatalk.com/groups/rgvfr/spacex-in-brownsville-t1680-s210.html

Does this mean Nomadd's trip is off, and we won't be getting his photos from the haze of Kelly's Pub?
Re arguments from authority on NSF:  "no one is exempt from error, and errors of authority are usually the worst kind.  Taking your word for things without question is no different than a bracket design not being tested because the designer was an old hand."
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Offline DigitalMan

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Re: SpaceX Texas launch site Discussion and Updates - Thread 9
« Reply #438 on: 01/13/2019 05:03 pm »
Since it is about 40 meters tall. Do anyone know if the hopper is visible from South Padre Island?

Very much so. Here's a link to the RGV forum that I follow. Someone took a picture from the Jetties of SPI:
https://www.tapatalk.com/groups/rgvfr/spacex-in-brownsville-t1680-s210.html

Does this mean Nomadd's trip is off, and we won't be getting his photos from the haze of Kelly's Pub?

Perhaps he can go and try getting a picture through a polarized lens?  Maybe by the end of the day everyone will be happy?

Online Step55

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Re: SpaceX Texas launch site Discussion and Updates - Thread 9
« Reply #439 on: 01/13/2019 05:23 pm »
I am sure that the strength of the concrete pad is important but I wonder if the dryness is not equal or more

so? Humidity at the coast amounts to dampness which leads to steam which makes exploding concrete!

Polypropylene fibers are usually added to concrete that will be exposed to high temperatures. At high temperatures they melt, leaving small passages for the steam to escape, preventing explosive spalling.

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