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Apparently the legs on this mission were reused:

"...coming in for a powered landing eight minutes after launch reaching its culmination with a gentle touchdown on four fold-out landing legs that had been recycled from a previous rocket."

http://spaceflight101.com/falcon-9-launches-dragon-spx-12-first-stage-landing-success/

Edited by TheEpicSquared
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I noticed the grid fins were doing a lot more correction during the landing burn than usual. Was it windy, or was the guidance system upgraded to be more precise? I noticed it landed right in the middle of the X whereas sometimes it tends to be a little off.

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31 minutes ago, Grand Ship Builder said:

Will SpaceX make more barge ships for the Falcon Heavy boosters, second stage, and possibly Dragon?

My understanding is the boosters will always return to the launch site; the second stage basically goes into orbit along with the payload, so if it were to be recovered it could land pretty much anywhere, possibly a once-around flight with a landing back at KSC; the Dragon 2 would've made its propulsive landings on land but now that they've given up on that idea, I believe it's planned to parachute into the ocean like previous capsules. 

So no, there should be no need for more than one barge per ocean.

Edited by Hotaru
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I still don't understand exactly what kind of trajectory the rocket flies and how it turns around to the launch site, even after watching the entire video from start to finish. How far down-range does it actually go before turning around?

The speed indicator doesn't seem to help. How much delta-v does the boost-back burn actually take up? It's still going thousands of km/h after the burn, but apparently the other way?

 

Edit: I did some rough calculations, and I'm guessing it needs 1-1.5 km/s delta-v. Still, would be nice to get more detailed data regarding the velocity vectors and distance.

Edited by Lukaszenko
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12 hours ago, cubinator said:

I noticed the grid fins were doing a lot more correction during the landing burn than usual. Was it windy, or was the guidance system upgraded to be more precise? I noticed it landed right in the middle of the X whereas sometimes it tends to be a little off.

From the way the exhaust flame flickered during the landing burn, it was very windy indeed.

 

50 minutes ago, Lukaszenko said:

I still don't understand exactly what kind of trajectory the rocket flies and how it turns around to the launch site, even after watching the entire video from start to finish. How far down-range does it actually go before turning around?

The speed indicator doesn't seem to help. How much delta-v does the boost-back burn actually take up? It's still going thousands of km/h after the burn, but apparently the other way?

The boostback burn doesn't arrest all velocity. It arrests (and reverses) the horizontal component. The rocket is still moving upwards at a good clip, therefore the speed indicator never reaches zero until the actual landing. They simply let gravity deal with vertical velocity.

Here is an infographic showing the principle. As for exact values for altitude and downrange distance, that differes from launch to launch. Overall though, the Falcon 9 flies a steeper trajectory than traditional rockets, and has a larger part of its total dV shifted to the second stage. Both of these things make first stage recovery easier.

Edited by Streetwind
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1 hour ago, Lukaszenko said:

I still don't understand exactly what kind of trajectory the rocket flies and how it turns around to the launch site, even after watching the entire video from start to finish. How far down-range does it actually go before turning around?

The speed indicator doesn't seem to help. How much delta-v does the boost-back burn actually take up? It's still going thousands of km/h after the burn, but apparently the other way?

 

Edit: I did some rough calculations, and I'm guessing it needs 1-1.5 km/s delta-v. Still, would be nice to get more detailed data regarding the velocity vectors and distance.

I assume that the velocity we see is the total velocity, i.e. the vector sum of F9's horizontal and vertical velocity. So a lot of the velocity after the burn will still be vertical velocity. Similarly the boostback burn only affects horizontal velocity (I presume), to arrest and possibly slightly reverse that velocity.

From the video, speed at MECO is 5877 km/hour or 1.63 Km/s. I'm not sure how much delta-V the boostback burn does impart but I think your estimate is probably a bit high. A 1.5 km/s burn would be nearly enough to stop the whole stage dead in mid air!

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1 hour ago, Lukaszenko said:

I still don't understand exactly what kind of trajectory the rocket flies and how it turns around to the launch site, even after watching the entire video from start to finish. How far down-range does it actually go before turning around?

Av1zFjc.png

As you can see, it doesn't simply burn retrograde. It reverts the horizontal vector but maintains the vertical component.

Edited by Nibb31
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48 minutes ago, KSK said:

From the video, speed at MECO is 5877 km/hour or 1.63 Km/s. I'm not sure how much delta-V the boostback burn does impart but I think your estimate is probably a bit high. A 1.5 km/s burn would be nearly enough to stop the whole stage dead in mid air!

I crudely timed how fast the altitude was changing, which gave me the vertical component. From this I figured out the horizontal (~1.1 km/s). In order to kill the horizontal and then hope to make it back, I guessed ~1.5 km/s would suffice. 

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On 14/08/2017 at 5:38 PM, Racescort666 said:

Just divide by 3.6 nbd.

I was going to make a joke about metric being easy to use but decided against it.

Last I checked, hours weren't part of metric. The use of hours is what makes the conversion awkward, not the use of km.

Edited by Damien_The_Unbeliever
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1 hour ago, Damien_The_Unbeliever said:

Last I checked, hours weren't part of metric. The use of hours is what makes the conversion awkward, not the use of km.

But still, divide by 3.6. There are 3600 seconds in an hour and 1000 meters in a km, so there are 3.6 km/hr in a single m/s.

Edited by sevenperforce
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At T+2:28, MECO, altitude is 61.1 km. At T+2:32, staging, altitude is 65.2 km. Thus, the average vertical component of velocity is 1.025 km/s. Since staging velocity is about 1.63 km/s, this means the horizontal component of velocity is roughly 1.27 km/s. However, Cape Canaveral is comoving underneath at a nice steady clip of 409 m/s, meaning that the Falcon 9 first stage only needs to kill about 860 m/s of downrange velocity to essentially "stop". 

16 hours ago, Hotaru said:

My understanding is the boosters will always return to the launch site; the second stage basically goes into orbit along with the payload, so if it were to be recovered it could land pretty much anywhere, possibly a once-around flight with a landing back at KSC; the Dragon 2 would've made its propulsive landings on land but now that they've given up on that idea, I believe it's planned to parachute into the ocean like previous capsules. 

So no, there should be no need for more than one barge per ocean.

In certain cases, there may be a need for both boosters to land on an ASDS. In such cases, the core will be going so fast that it will almost certainly be expended. So they will probably need one more ASDS for the Atlantic. I don't anticipate another one for the Pacific.

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10 hours ago, sevenperforce said:

....this means the horizontal component of velocity is roughly 1.27 km/s. However, Cape Canaveral is comoving underneath at a nice steady clip of 409 m/s, meaning that the Falcon 9 first stage only needs to kill about 860 m/s of downrange velocity to essentially "stop". 

You lost me...how/ why is the cape moving slower than the rocket? 

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