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#220
by
Robotbeat
on 16 May, 2017 02:06
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Why not count the dispenser? It's Iridium hardware. Seems to me everything forward of the Payload adapter should be considered payload even if it isn't technically deployed. It was still carried to space.
IIRC, SpaceX built it. I disagree with Ed that it should not be counted as payload, at least when considering established lift capability of the rocket, as a different payload could use that mass for something else.
You are talking about something that ULA calls "Payload Systems Weight", which is a legitimate way to record things. For Ariane 5 it means including Sylda 5, etc. For other launches it includes the PAF, etc. If you are using that method for Dragon, you would also have to add Dragon's adapter, etc. That's all fine, but I'm interested in deployed payload because that is what matters in the rocket equation.
- Ed Kyle
Was the Iridium payload adapter on top of a regular payload adapter? If so, then it should be counted as payload. If it was in /place/ of the regular payload adapter, then you can count it as Stage 2. We're talking about the maximum payload mass a Falcon 9 has proven it could launch, and if the former is true, then it'd be factually incorrect to assert it has proven less.
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#221
by
Mongo62
on 16 May, 2017 02:08
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- 36000 km/sec seems like an awfully round number. Maybe not a burn to residual shutdown?
It also seems like an awfully
fast number. 12% of the speed of light!
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#222
by
abaddon
on 16 May, 2017 02:09
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You'd ideally count the custom dispenser mass minus the mass of a standard payload adapter. The Iridium dispenser is much more massive in comparison.
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#223
by
gongora
on 16 May, 2017 02:14
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Maybe this was a hardware Block 4 with Block 3 thrust, incremental deployment?
Has SpaceX ever said anything about what a "Block 4" would consist of, exactly? We know Block 5 will have uprated thrust, just don't recall them ever saying much of anything about Block 4
Agreed, it's not been well explained. I believe that Block 4 is up rated thrust, COPV solution.
Block 5 is the reuseability upgrades, new legs, heat shield etc.
COPV fix was previously said to be in block 5, along with turbopump tweaks and the reuseability stuff. The only thing we ever heard for block 4 was uprated thrust.
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#224
by
abaddon
on 16 May, 2017 02:15
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There were two COPV fixes, one short term and one in Block 5. Believe the latter was at request of NASA and maybe USAF.
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#225
by
cppetrie
on 16 May, 2017 02:25
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There were two COPV fixes, one short term and one in Block 5. Believe the latter was at request of NASA and maybe USAF.
I thought the NASA request related to long-term fixes for turbo-pump cracking.
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#226
by
Robotbeat
on 16 May, 2017 02:26
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There were two COPV fixes, one short term and one in Block 5. Believe the latter was at request of NASA and maybe USAF.
I thought the NASA request related to long-term fixes for turbo-pump cracking.
NASA tends to have lots of requests.
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#227
by
cppetrie
on 16 May, 2017 02:27
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There were two COPV fixes, one short term and one in Block 5. Believe the latter was at request of NASA and maybe USAF.
I thought the NASA request related to long-term fixes for turbo-pump cracking.
NASA tends to have lots of requests.
True story.
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#228
by
sewebster
on 16 May, 2017 03:26
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Gabon AOS.
Libreville's not in business for this launch, I guess.
Isn't the tracking station near Libreville?
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#229
by
ZachS09
on 16 May, 2017 04:44
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I think there are two different tracking stations in Gabon.
The regular Gabon station and the Libreville station. Unless they refer to Libreville as "Gabon".
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#230
by
Lars-J
on 16 May, 2017 05:00
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#231
by
sewebster
on 16 May, 2017 05:02
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#232
by
manoweb
on 16 May, 2017 05:05
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It could also have been for an abundance of caution in terms of giving information on speeds etc.
Actually it's the opposite, the previous launch gave a LOT of information on the first stage, this one FULL flight profile of the second stage from takeoff to the end. I have been extracting the data with an automated script in another thread
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#233
by
Pete
on 16 May, 2017 08:39
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Is it just me, or have they trimmed down the time from MECO to Second stage Ignition even further?
Yes, they did not need to give the first stage time to get out of the blast zone, but it still felt like the speediest second stage startup I've yet seen?
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#234
by
Ben the Space Brit
on 16 May, 2017 08:41
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The fastest MECO to SECO1 I've ever seen was so fast that you saw the Merlin VAC's exhaust plume hit the first stage and bounce off of the top dome of the LOX tank, focussed back towards the U/S by the interstage. I'm sure that it made an interesting bit of data about high-energy fluid dynamics in near-vacuum!
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#235
by
input~2
on 16 May, 2017 09:29
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AFAICT no TLE published yet
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#236
by
gospacex
on 16 May, 2017 09:44
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SpaceX's heaviest payloads to date. All were launched in 2017.
1. Iridium Next (1-10) - LEO (9,600 kg)
2. Inmarsat-5 F4 - GTO (6,070 kg)
3. EchoStar 23 - GTO (5,600 kg)
Dont forget about the Dragon launches. Those will be right in there near #1
Those are LEO launches [edit: Iridium and Dragon]. For LEO, ~10 tons is not much - it's only about half of what F9 can do.
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#237
by
longboard1210
on 16 May, 2017 12:08
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If the plume pushed against the 1st stage would the intial aceleration be larger than straight into vaccum?
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#238
by
curtquarquesso
on 16 May, 2017 12:26
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If the plume pushed against the 1st stage would the intial aceleration be larger than straight into vaccum?
No. A rocket engine's thrust is a result of it throwing many thousands of pounds of propellant out of the nozzle, opposite the desired direction of travel independent of whatever is behind it. Tom Mueller had a great practical example in his recent interview. A rocket engine works on the same principle as sitting in the back of the wagon, and throwing a brick out the back of it. You'll get a small impulse from throwing a brick opposite the direction you want to travel. If you could throw thousands of pounds of bricks out the back continuously, you'd move very, very quickly.
(mass of brick) * (acceleration experienced by brick being thrown by you) = (force of brick leaving your hand, pushing you and wagon forward)
F = Ma
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#239
by
BabaORileyUSA
on 16 May, 2017 13:27
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SpaceX's heaviest payloads to date. All were launched in 2017.
1. Iridium Next (1-10) - LEO (9,600 kg)
2. Inmarsat-5 F4 - GTO (6,070 kg)
3. EchoStar 23 - GTO (5,600 kg)
Dont forget about the Dragon launches. Those will be right in there near #1
Those are LEO launches. For LEO, ~10 tons is not much - it's only about half of what F9 can do.
This was NOT a flight to GTO! This used a super-synchronous transfer orbit.
