totm nov 2023 SpaceX Discussion Thread

[CatastrophicFailure]

It appears ArianeSpace is having a very bad day, which makes me wonder... would the James Webb scope fit in a Falcon Heavy?

[Canopus]

1 minute ago, CatastrophicFailure said:

It appears ArianeSpace is having a very bad day, which makes me wonder... would the James Webb scope fit in a Falcon Heavy?

As if they would launch it on a Falcon with that launchers reliable history. They would always go to ULA first.

[tater]

21 minutes ago, Canopus said:

As if they would launch it on a Falcon with that launchers reliable history. They would always go to ULA first.

This. The probability of jwst on FH is zero. It wouldn’t fit, anyway. They’d certainly feel better if A5 had a 17 year winning streak, though.

[sh1pman]

Everyone has their bad day, I guess. Even with very reliable rockets.

Kinda explains why I don’t see passenger Earth to Earth BFRs happening. 

 

Edited January 26, 2018 by sh1pman

[DAL59]

2 hours ago, sh1pman said:

Kinda explains why I don’t see passenger Earth to Earth BFRs happening. 

Planes also crash, but we still ride them.  

[tater]

1 minute ago, DAL59 said:

Planes also crash, but we still ride them.  

 There are ~2 accidents on airlines per million departures. Not fatal accidents, accidents of any kind, like wings hitting things on the taxiway.

P2P BFR has to demonstrate rather a lot of perfect flights to catch up to that. Step 1: it needs to exist.

[PB666]

4 hours ago, CatastrophicFailure said:

It appears ArianeSpace is having a very bad day, which makes me wonder... would the James Webb scope fit in a Falcon Heavy?

ArianeSpace had a great day, three payloads separated.

[tater]

The problem with interest/press is that people notice when anything is amiss. Back in the day, no one cared, and the most news that would happen about a comsat launch might be a line in the Aviation Week article that said that it "briefly lost telemetry while successfully deploying the payloads."

Now people are watching and commenting in real time.

[tater]

 

[PB666]

45 minutes ago, tater said:

The problem with interest/press is that people notice when anything is amiss. Back in the day, no one cared, and the most news that would happen about a comsat launch might be a line in the Aviation Week article that said that it "briefly lost telemetry while successfully deploying the payloads."

Now people are watching and commenting in real time.

Somehow briefly go translated into images showing the satellite barreling back to Earth. There is reality and hype, given the modern overexposure to hype, they should be easily distinguished.

Edited January 26, 2018 by PB666

[CatastrophicFailure]

1 hour ago, PB666 said:

ArianeSpace had a great day, three payloads separated.

At the time, that did not appear to be the case, especially with the chief up there slinging mea culpas. 

53 minutes ago, tater said:

The problem with interest/press is that people notice when anything is amiss. Back in the day, no one cared, and the most news that would happen about a comsat launch might be a line in the Aviation Week article that said that it "briefly lost telemetry while successfully deploying the payloads."

Now people are watching and commenting in real time.

Part of the problem also, I think, is the industry standard of calling every single off-nominal event an “anomaly” regardless of magnitude or, ahem, gravity. 

If they’d call a kaboom a kaboom and a loss of signal a loss of signal, instead of trying to spin and sugarcoat everything, the “reality” would be much more distinguishable. 

[PB666]

8 minutes ago, CatastrophicFailure said:

At the time, that did not appear to be the case, especially with the chief up there slinging mea culpas. 

I saw nothing but a successful flight with a bit of an annoying/confusing telemetry display. I saw nothing that would indicate the flight had failed.

EDIT: This will be my last response on the topic, I was correcting an entirely incorrect statement that was off-topic in this thread to begin with, the moderators are cracking down on off-topic so if you want to respond take it to the Ariannespace thread.

Edited January 26, 2018 by PB666

[CatastrophicFailure]

2 minutes ago, PB666 said:

I saw nothing but a successful flight with a bit of an annoying/confusing telemetry display. I saw nothing that would indicate the flight had failed.

Then you didn’t see this guy, apparently a figure of some authority, pretty much apologizing because the flight had failed...

[PakledHostage]

11 hours ago, Just Jim said:

The even bigger problem with driving over for launches is getting all the way over there, only to have it scrubbed at the last second and pushed back a day or three.  

Tell me about it... I flew all the way across the continent to see the launch of STS-101 (and boy were my arms tired!), only to have it scrubbed at the T-9 hold due to high winds. But I'm off topic again...

[PakledHostage]

I should add that my only regret is that I never tried again...

[RCgothic]

17 hours ago, RCgothic said:

Falcon Heavy is something like 8.2 tonnes per second. 

Assuming Saturn V dumps negligible propellant into the flame trench after it clears the tower (exhaust slowed by distance, "aim" of exhaust wanders) then with a linear reduction it would need to take longer than 14.5s to exceed the Falcon Heavy's static fire. It doesn't take that long, so Falcon Heavy probably wins.

But it's moving slowly to begin with. Assuming again zero as Saturn clears the tower and, 10s to clear the tower, and reduction proportional to distance ascended.... I'll do the maths later if nobody else beats me to it. I think it's close.

Assume that thrust decays to zero at 10s when Saturn V clears the tower from 100% at t=0 at constant acceleration.

Distance s=ut+0.5at^2 condenses to s=0.5at^2

Rescaling y=0.5mt^2 with y between 0 and 1 allows us to find the constant m as 0.02/s^2

Area under that curve is A =1/6 * mt^3, or 3.33s out of a total area of 1*10s =10s. The area not under this curve is the weighted thrust fraction, 6.66s

The average thrust fraction is therefore 0.66. So with a total fuel consumption of 13.6 te per second, Saturn's average thrust per second is 9.0 te per second. 

This beats Falcon Heavy over 10s (90te Vs 82te) but not if Falcon Heavy gets an extra 2s test (98.4te).

Falcon Heavy hold down static fire is therefore a more extreme test for the flame trench than Saturn V in terms of total propellant. And with a higher ISP and exhaust velocity it's likely to be a harsher test in that regard too.

Edited January 26, 2018 by RCgothic

[tater]

 

[tater]

 

[CatastrophicFailure]

Woohoo still on for the 30th!

 

[Thor Wotansen]

So we might see back to back east coast SpaceX launches, cool.

[CatastrophicFailure]

Guysguygguysguysguysguysguysguys!!!!!!!!!!!

...subject to change without notice, of course. 

Edited January 26, 2018 by CatastrophicFailure

[Scotius]

Hype cannon is locked, loaded and ready to fire Three-in-one Falcon launches.

[Ultimate Steve]

WOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOHOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO!!!!!!!!!!!!!!!!!!!!!!!

 

T minus eight days and counting...

 

EDIT: Nope, sorry, eleven days. I forgot it was still January.

Which means I won't be able to watch unless I skip school...

EDIT2: You know you're desperate when you want to be sick enough to skip school for a rocket launch.

Edited January 26, 2018 by Ultimate Steve

[cubinator]

I have lunch, then a STEM class during the first hour and twenty minutes of the launch window, so I should be fine.

[CatastrophicFailure]

6 minutes ago, cubinator said:

I have lunch, then a STEM class during the first hour and twenty minutes of the launch window, so I should be fine.

STEM class? The It should be required viewing! Same goes for @Ultimate Steve, too. 

This is gonna be my Super Bowl.