### Author Topic: SpaceX Eastern Range Landing Facilities  (Read 226690 times)

#### launchwatcher

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##### Re: SpaceX Eastern Range Landing Facilities
« Reply #460 on: 10/09/2017 10:30 PM »
Looks like the North pad is progressing nicely. Not 100% certain but looks like about half of the concrete has been poured.
https://www.instagram.com/p/BaCPZEWl253/?taken-by=tedwardmeyer

It looks to me like the center square has been pored and that they are poring half circle shapes around the square to make a full circle. One of these half circles (out of 4) appears to be pored. So, I'd say they are over halfway done.
Agree. Looks like they poured the largest possible square that fits inside the circle and are now pouring the chord segments that complete the circle. If my memory of geometry and math and my quick calculation is correct they are actually ~73% done. Can anyone verify my math?
a circle with radius 1 has an area of pi.
the inscribed square has a diagonal of length 2, sides of sqrt(2) and thus area 2.

3/4 of the square plus 1/4 of the circle is (1.5 + pi/4); divide the whole thing by pi to get the ratio; the number I get rounds to 73%

So yes they've poured ~73% of the concrete.   No idea what that means in terms of actual project completion.

#### AnalogMan

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##### Re: SpaceX Eastern Range Landing Facilities
« Reply #461 on: 10/10/2017 01:25 AM »
And, if memory serves, the new landing pad will not be much larger than the 'bulls eye' of the first landing pad.

The concrete areas are the same size, but the surrounding gravel ring will be smaller.

Here's a site plan from February this year giving the dimensions of the new North Pad.  The second drawing shows a cross-section through the pad showing some construction details (the red line on the site plan shows the location of the cross-section). Note that the pad is slightly crowned - the center is 1.25 feet higher than the outer edge of the compacted aggregate ring.

#### old_sellsword

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##### Re: SpaceX Eastern Range Landing Facilities
« Reply #462 on: 10/10/2017 02:16 AM »
And, if memory serves, the new landing pad will not be much larger than the 'bulls eye' of the first landing pad.

The concrete areas are the same size, but the surrounding gravel ring will be smaller.

Here's a site plan from February this year giving the dimensions of the new North Pad.  The second drawing shows a cross-section through the pad showing some construction details (the red line on the site plan shows the location of the cross-section). Note that the pad is slightly crowned - the center is 1.25 feet higher than the outer edge of the compacted aggregate ring.

These are great drawings, where do they come from?

#### vanoord

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##### Re: SpaceX Eastern Range Landing Facilities
« Reply #463 on: 10/10/2017 09:36 AM »
Approximately a 1:200 fall from the centre of the concrete pad to the edge - will enable drainage, but probably wouldn't be noticeable unless you got very close.
« Last Edit: 10/10/2017 09:37 AM by vanoord »

#### LouScheffer

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##### Re: SpaceX Eastern Range Landing Facilities
« Reply #464 on: 10/10/2017 01:54 PM »
Random SpaceX numerology:   The dimensions of the concrete circle seem oddly specific.  The concrete pad is spec'ed as 282.84 feet in diameter.   It's not an even number in metric either - 86.21 meters.  It covers some odd fraction of the outer ring - 46.45%.  The area is not a round number in square feet or meters.   The outer ring is 415 feet exactly, so they are not averse to rounding to even values.

But if you work out the size of the central square, it's exactly 200 x 200 feet.  So they likely designed a square of this size, then expanded it to a circle.

#### meekGee

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##### Re: SpaceX Eastern Range Landing Facilities
« Reply #465 on: 10/10/2017 02:14 PM »
Random SpaceX numerology:   The dimensions of the concrete circle seem oddly specific.  The concrete pad is spec'ed as 282.84 feet in diameter.   It's not an even number in metric either - 86.21 meters.  It covers some odd fraction of the outer ring - 46.45%.  The area is not a round number in square feet or meters.   The outer ring is 415 feet exactly, so they are not averse to rounding to even values.

But if you work out the size of the central square, it's exactly 200 x 200 feet.  So they likely designed a square of this size, then expanded it to a circle.
In other words, 2828 is 2000*✓2.

I don't think you can put root values in construction plans, even if you really really want to.
ABCD - Always Be Counting Down

#### cppetrie

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##### Re: SpaceX Eastern Range Landing Facilities
« Reply #466 on: 10/10/2017 06:10 PM »
Given the way it was constructed (by pouring a square first and then rounding the edges), it may have made the most sense to define the square’s dimension in nice round numbers and let the rest of the final shape dimensions just be whatever they turn out to be.

#### Coastal Ron

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##### Re: SpaceX Eastern Range Landing Facilities
« Reply #467 on: 10/10/2017 06:20 PM »
Note that the pad is slightly crowned - the center is 1.25 feet higher than the outer edge of the compacted aggregate ring.

Curvature of the Earth? They want to shed water quickly after a rain?

Any ideas why they are doing that?
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#### envy887

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##### Re: SpaceX Eastern Range Landing Facilities
« Reply #468 on: 10/10/2017 06:23 PM »
Note that the pad is slightly crowned - the center is 1.25 feet higher than the outer edge of the compacted aggregate ring.

Curvature of the Earth? They want to shed water quickly after a rain?

Any ideas why they are doing that?

To avoid water puddling on the surface, undoubtedly.

#### meberbs

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##### Re: SpaceX Eastern Range Landing Facilities
« Reply #469 on: 10/10/2017 06:27 PM »
Note that the pad is slightly crowned - the center is 1.25 feet higher than the outer edge of the compacted aggregate ring.

Curvature of the Earth? They want to shed water quickly after a rain?

Any ideas why they are doing that?

To avoid water puddling on the surface, undoubtedly.
Agreed. Sidenote: curvature of the Earth should be around one thousandth of an inch on that scale if I did the math right.

#### cppetrie

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##### Re: SpaceX Eastern Range Landing Facilities
« Reply #470 on: 10/10/2017 07:50 PM »
Note that the pad is slightly crowned - the center is 1.25 feet higher than the outer edge of the compacted aggregate ring.

Curvature of the Earth? They want to shed water quickly after a rain?

Any ideas why they are doing that?

To avoid water puddling on the surface, undoubtedly.
Most definitely. Same reason that playing fields, roads and many other “flat” surfaces are actually crowned. Standing water is bad for many reasons.

#### Jdeshetler

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##### Re: SpaceX Eastern Range Landing Facilities
« Reply #471 on: 10/17/2017 10:07 PM »
1/8" for every foot or 1% slope is a standard runs off for any exterior surfaces except for flat roof which must be double, 1/4" or 2% slope.

#### Ronsmytheiii

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##### Re: SpaceX Eastern Range Landing Facilities
« Reply #472 on: 10/20/2017 06:04 PM »
Concrete pad almost done for the north pad, looks like the south area has been cleared for the new Dragon building construction:

https://www.planet.com/explorer
And this is a good reminder that just because one of your fellow space enthusiasts occasionally voices doubts about the SpaceX schedule announcements or is cautious about believing SpaceX has licked a problem before actually seeing proof that's true, it doesn't mean they hate SpaceX.

#### Gotorah

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##### Re: SpaceX Eastern Range Landing Facilities
« Reply #473 on: 10/20/2017 06:16 PM »
The concrete needs to be kept as dry as possible. Wet concrete when quickly heated will spall and very quickly erode in the high temperature, high velocity engine exhaust.

#### georgegassaway

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##### Re: SpaceX Eastern Range Landing Facilities
« Reply #474 on: 10/20/2017 11:41 PM »
Well, if they want to try to keep the concrete as dry as possible, I could envision a baseball stadium type of "Field Crew" laying out a huge tarp when it's going to rain within 48 hours of a launch/landing.  And then the crew would go out and fold/roll the tarp up an hour or so before launch-ding  ("Launch-ding",  did I just invent a term?    ).

Of course, the tarp would have the SpaceX logo on it.

Also of course, I am not serious about them really doing that....

#### Herb Schaltegger

##### Re: SpaceX Eastern Range Landing Facilities
« Reply #475 on: 10/21/2017 01:26 AM »
The concrete needs to be kept as dry as possible. Wet concrete when quickly heated will spall and very quickly erode in the high temperature, high velocity engine exhaust.

You do realize, don't you #1) freshly poured concrete is generally wetted gently over a period of a day or two (or longer, depending on thickness) to prevent it from curing too quickly and thus cracking; and #2) this pad is in a sub-tropical climate and will be exposed to almost-daily showers for months on end? :p

#### Robotbeat

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##### Re: SpaceX Eastern Range Landing Facilities
« Reply #476 on: 10/21/2017 02:30 AM »
And SpaceX is using some kind of special heat-resistant cement, I think. And a generous layer of radar-reflective paint.
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#### CyndyC

##### Re: SpaceX Eastern Range Landing Facilities
« Reply #477 on: 11/30/2017 03:47 PM »
And SpaceX is using some kind of special heat-resistant cement, I think. And a generous layer of radar-reflective paint.

It doesn't seem it would matter whether or not the concrete itself is heat resistant if it's coated with reflective paint, and is radar ever aimed at the ground? Maybe you meant infrared-reflective, since satellite-mounted infrared cameras measure heat, and just such a coating called CoolSeal is used to help keep spy planes cool and hide them.

There was a discussion about concrete reflectance that started in the permits thread in July of last year, which Lar had to put a stop to because it was drifting off into a discussion of Los Angeles climate control, which had been mentioned in a research paper I had posted about variations in the potential of different forms of concrete to reflect heat. I was excited to see our discussion might have helped galvanize an effort in LA to act on the research beginning in April or May of this year, but not suggesting we should drift off to LA again, just that the following might be the same thing SpaceX has done/is doing with their landing pads as white as they appear in daytime imagery:

Quote
http://www.sciencemag.org/news/2017/09/los-angeles-paints-streets-white-stay-cool [with photo]

Los Angeles, California, in the summertime can be, for lack of a better word, a hellscape. It is the quintessential smog-laden, traffic-jammed, heat island, but a new initiative from Mayor Eric Garcetti aims to help cool the city by 1.67°C over the next 20 years. Part of the plan, Popular Science reports, is to paint over many of the city’s black roads with a reflective white coating called CoolSeal originally designed by the military to keep spy planes cool and hide them from satellite infrared cameras. Adding the coating to a patch of black asphalt can keep the area up to 5.55°C cooler, a difference that could prove vital as global temperatures continue to increase.

And below would be how they are doing it:

« Last Edit: 11/30/2017 03:54 PM by CyndyC »
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#### whitelancer64

##### Re: SpaceX Eastern Range Landing Facilities
« Reply #478 on: 11/30/2017 04:05 PM »
And SpaceX is using some kind of special heat-resistant cement, I think. And a generous layer of radar-reflective paint.

It doesn't seem it would matter whether or not the concrete itself is heat resistant if it's coated with reflective paint, and is radar ever aimed at the ground? *snip*

The landing radar on the Falcon 9 rocket is.
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#### CyndyC

##### Re: SpaceX Eastern Range Landing Facilities
« Reply #479 on: 11/30/2017 04:30 PM »
This might be a stupid question, but what's the point of a landing radar since the trajectory is pre-programmed and can't be changed mid-flight from the ground, or is it just the launch trajectory that can't [per Jim}? Is the AFTS re-armed for landings?
"Either lead, follow, or get out of the way." -- quote of debatable origin tweeted by Ted Turner and previously seen on his desk

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