Author Topic: SpaceX Falcon 9 FT - ORBCOMM-2 - RTF (Return To Flight) DISCUSSION THREAD  (Read 875874 times)


Offline Steven Pietrobon

  • Member
  • Senior Member
  • *****
  • Posts: 12574
  • Adelaide, Australia
    • Steven Pietrobon's Space Archive
  • Liked: 2750
  • Likes Given: 410
Here's a couple of enhanced images.
« Last Edit: 09/25/2015 07:57 AM by Steven Pietrobon »
Akin's Laws of Spacecraft Design #1:  Engineering is done with numbers.  Analysis without numbers is only an opinion.

Offline mn

  • Full Member
  • **
  • Posts: 200
  • United States
  • Liked: 93
  • Likes Given: 31
Question: does spacex have to issue an official report that needs to be signed off by faa (or some other agency) before they can RTF? (would such a report have to be public?)

Or is spacex free to launch whenever they (and their customer) are ready?

Thank you

Offline ChefPat

  • Full Member
  • ****
  • Posts: 1050
  • Earth, for now
  • Liked: 121
  • Likes Given: 1010
Awesome.

... but I can't help but notice the logo is covered in a sheet of ice, thanks to the chilled RP1  :P
No kidding! I wonder if the added mass of ice from condensation will make a difference in the mass of the vehicle?
Playing Politics with Commercial Crew is Un-American!!!

Offline Joaosg

Awesome.

... but I can't help but notice the logo is covered in a sheet of ice, thanks to the chilled RP1  :P
No kidding! I wonder if the added mass of ice from condensation will make a difference in the mass of the vehicle?

I think most of the ice falls in the first moments of launch.

Offline NovaSilisko

  • Full Member
  • ****
  • Posts: 1828
  • Liked: 1435
  • Likes Given: 1305
Awesome.

... but I can't help but notice the logo is covered in a sheet of ice, thanks to the chilled RP1  :P
No kidding! I wonder if the added mass of ice from condensation will make a difference in the mass of the vehicle?

I think most of the ice falls in the first moments of launch.

...which makes me hopeful they'll start using a full-body logo. I mean, if you've got ice on both top and bottom, what's the loss?  :P I do hope they figure some way of making it more visible pre-launch though, perhaps raised letters or some sort of non-stick coating...

Offline Lars-J

  • Senior Member
  • *****
  • Posts: 3397
  • California
  • Liked: 2636
  • Likes Given: 1664
Why is the logo on the rocket so important?

Offline NovaSilisko

  • Full Member
  • ****
  • Posts: 1828
  • Liked: 1435
  • Likes Given: 1305
Why is the logo on the rocket so important?

'cause it's cool.  :)

Offline kch

  • Full Member
  • ****
  • Posts: 1731
  • Liked: 466
  • Likes Given: 8318
Why is the logo on the rocket so important?

'cause it's cool.  :)

Downright frosty, in fact ... :D

Offline macpacheco

  • Full Member
  • ****
  • Posts: 804
  • Vitoria-ES-Brazil
  • Liked: 315
  • Likes Given: 2328
Question: does spacex have to issue an official report that needs to be signed off by faa (or some other agency) before they can RTF? (would such a report have to be public?)

Or is spacex free to launch whenever they (and their customer) are ready?

Thank you
I believe large rockets are regulated under experimental aircraft category, but due to their large explosive content, the FAA probably requires more paperwork, but it's not subject to any formal certification (due to their expendable nature).

The FAA main concern is danger to the public.

I think its a gray area, in which the FAA could forbid SpaceX from launching if they had serious enough concerns, and SpaceX has every interest in keeping the FAA involved and happy with the accident investigation.

The other issue is Air Force has authority over both ranges SpaceX currently operates from. So they could also forbid launches if they have concerns.

In all likelyhood this isn't a paperwork issue, but rather keeping both the FAA and Air Force happy SpaceX is taking the issue seriously and is putting every effort to ensure the problem will be explained and fixed.

I suppose SpaceX has a much bigger stake than FAA or USAF on this. One launch failure is acceptable. A second launch failure (without at least a dozen successful ones in between) could be the kiss of death for SpaceX.

Moderators feel free to pull this is this is too much speculation... Even being L1 and all.
Looking for companies doing great things for much more than money

Offline Jim

  • Night Gator
  • Senior Member
  • *****
  • Posts: 31222
  • Cape Canaveral Spaceport
  • Liked: 9494
  • Likes Given: 298

I believe large rockets are regulated under experimental aircraft category,

No, they have their own regulations

Offline llanitedave

  • Senior Member
  • *****
  • Posts: 2087
  • Nevada Desert
  • Liked: 1267
  • Likes Given: 1465
Why is the logo on the rocket so important?


Well, we wouldn't want anyone mistaking it for a Vulcan, now would we?   8)
"I've just abducted an alien -- now what?"

Offline Jim

  • Night Gator
  • Senior Member
  • *****
  • Posts: 31222
  • Cape Canaveral Spaceport
  • Liked: 9494
  • Likes Given: 298
Why is the logo on the rocket so important?

So you can find the pieces.

Offline Semmel

  • Full Member
  • ****
  • Posts: 1081
  • Germany
  • Liked: 768
  • Likes Given: 2219
I never thought you could be that sarcastic Jim.

The logo is good PR because people instantly can recognize the rocket without knowing its outlines or properties. Think about it, the average person would confuse an iphone with an other brand if it hadnt a half eaten apple on it.. Rockets are even worse since they are not such a common sight.

Offline Roy_H

  • Full Member
  • ****
  • Posts: 717
  • Liked: 183
  • Likes Given: 1163
I am really confused about this temperature of liquid oxygen. Triple Point of Oxygen is 54.36K or -361.8F at 146.27Pa or 0.0014 atmospheres or 0.0212 lbs/sq in. http://coolprop.sourceforge.net/fluid_properties/fluids/Oxygen.html
Oxygen has a freezing point of 54.36 K (−218.79 C; -361.82 F) and a boiling point of 90.19 K (−182.96 C; −297.33 F) at 101.325 kPa or 1.0 Atm. https://en.wikipedia.org/wiki/Liquid_oxygen

So coincidentally freezing point at 1 atm is about the same as the triple point. I don't think the properties of oxygen at 0.0014 atm are at all relevant, what is important it that it is close to and above freezing point at the pressures it will be stored and used at.

So can somebody explain why the term Triple Point is used instead of Freezing Point, which I think is both more understandable and relevant.
"If we don't achieve re-usability, I will consider SpaceX to be a failure." - Elon Musk

Offline mme

  • Full Member
  • ****
  • Posts: 1018
  • Santa Barbara, CA, USA, Earth, Solar System, Milky Way Galaxy, Virgo Supercluster
  • Liked: 1234
  • Likes Given: 3089
I am really confused about this temperature of liquid oxygen. Triple Point of Oxygen is 54.36K or -361.8F at 146.27Pa or 0.0014 atmospheres or 0.0212 lbs/sq in. http://coolprop.sourceforge.net/fluid_properties/fluids/Oxygen.html
Oxygen has a freezing point of 54.36 K (−218.79 C; -361.82 F) and a boiling point of 90.19 K (−182.96 C; −297.33 F) at 101.325 kPa or 1.0 Atm. https://en.wikipedia.org/wiki/Liquid_oxygen

So coincidentally freezing point at 1 atm is about the same as the triple point. I don't think the properties of oxygen at 0.0014 atm are at all relevant, what is important it that it is close to and above freezing point at the pressures it will be stored and used at.

So can somebody explain why the term Triple Point is used instead of Freezing Point, which I think is both more understandable and relevant.
I think it's just a matter of using terminology that is consistent and accurate.  In engineering systems where it's important that the substance exist in liquid form, the triple point is really important.  Why change terminology for a specific application where the triple point happens to be outside the typical operating environment?
Space is not Highlander.  There can, and will, be more than one.

Offline The Amazing Catstronaut

  • Full Member
  • ****
  • Posts: 1071
  • Arsia Mons, Mars, Sol IV, Inner Solar Solar System, Sol system.
  • Liked: 755
  • Likes Given: 628
Why is the logo on the rocket so important?

So you can find the pieces.

Jim tropes aside...

lt's a valid point. It is easier to identify tank wreckage when said wreckage has a logo on it, than when it does not.
Resident feline spaceflight expert. Knows nothing of value about human spaceflight.

Offline Norm Hartnett

  • Elite Veteran
  • Senior Member
  • *****
  • Posts: 2304
  • Liked: 53
  • Likes Given: 2
Why is the logo on the rocket so important?

So you can find the pieces.

Jim tropes aside...

lt's a valid point. It is easier to identify tank wreckage when said wreckage has a logo on it, than when it does not.

It is not so much finding the pieces as it is the logo helps in reassembly (so to speak). Like a jig saw puzzle having a pattern helps.
You cant take a traditional approach and expect anything but the traditional results, which has been broken budgets and not fielding any flight hardware. Mike Gold - Apollo, STS, CxP; those that don't learn from history are condemned to repeat it: SLS.

Offline Danny452

  • Member
  • Posts: 13
  • London, UK
  • Liked: 1
  • Likes Given: 22
Spacex will attempt to land the first stage, with full thrust engines, on Return To Flight.  As I understand it the previous engines had too much thrust for landing, so that even a throttled down single engine provided thrust greater than the weight of the first stage.  This requires the "hoverslam" landing with little room for error.

Will this problem be even worse with the full thrust engines or will they be able to throttle down a greater percentage to eg equal the minimum thrust of the previous engines?

Offline macpacheco

  • Full Member
  • ****
  • Posts: 804
  • Vitoria-ES-Brazil
  • Liked: 315
  • Likes Given: 2328
Spacex will attempt to land the first stage, with full thrust engines, on Return To Flight.  As I understand it the previous engines had too much thrust for landing, so that even a throttled down single engine provided thrust greater than the weight of the first stage.  This requires the "hoverslam" landing with little room for error.

Will this problem be even worse with the full thrust engines or will they be able to throttle down a greater percentage to eg equal the minimum thrust of the previous engines?
There's no new/old M1D engines, M1D engines were able to reach higher thrust all along, so minimum thrust should be the same.
The issue was qualifying the engines/stage for higher thrust, modifying the fuel tank ratios to handle optimized RP1 to LOX ratios and totals. There are changes to 2nd stage nozzle too.
Those are just my conclusions from prior discussions, I haven't seen technical data from SpaceX to confirm this precisely, but it seems clear enough.
Also the empty stage might be slightly heavier, which would help in Thrust:Weight ratios for landing.
Let's not restart this hover slam discussion, there's no hover, it continues decelerating with the engine shutting down right at touchdown.
Looking for companies doing great things for much more than money

Tags: