SpaceX News

[ladajo]

For those who missed it:
https://www.youtube.com/watch?v=xlnIT39NkVM

The significance here is that this was a GTO flight. I don't know the weight of JCSAT-14, however it would seem she was heavy given the landing kinematics (3 engine decel/landing burn).
Musk has but two boxes to check, re-flight of the LEO booster, and re-flight of the GTO booster to validate his model.

Arguably, the GTO landing indicates that he could conceivably orbit a LEO booster, and then bring it back. I wonder if that is in the cards for fun?

[TDPerk]

If the same proportions given for the Falcon Heavy apply to the BFR which is intended to loft the MCT, then the BFR would be able to orbit 550 tons to LEO, correct?

*SpaceX acronyms BFR = Big F*cking Rocket and MCT = Mars Colonial Transporter

[ladajo]

That sounds high, we would need to run the numbers. Could be. Off the top of my head I don't know.

[Skipjack]

J-Sat 14 was around 4700kg. I am not sure if that is the dry mass or the mass of the entire payload.

[ladajo]

The SpaceX posted capabilities says 22,200 kg to GTO with Falcon Heavy, and 8,300 kg to GTO with Falcon 9.
For LEO with an expended booster, it is saying 54,400 kg for Heavy, and 22,800 kg for 9.
So that is roughly 55 metric tons / 60 tons to LEO with a Heavy that you don't get back.

I am not sure where 550 tons comes from, that is very high (like a magnitude), unless it was a typo, and you meant 55 metric tons.

There is a conflict, but may be in the difference between recovered boosters, with a stated 5.5mT for 9 and 8mT for Heavy to GTO in fine print.

http://www.spacex.com/about/capabilities

[TDPerk]

J-Sat 14 was around 4700kg. I am not sure if that is the dry mass or the mass of the entire payload.

To be clear, I am extrapolating from the published numbers for the FH comparing Mars payload to LEO payload, and extrapolating from the published goal of 100 tons to Mars for the BFR to arrive at a tons to LEO for the BFR. If the MCT and BFR end up using two launches to fuel in orbit for Mars, that changes things substanitally.

The launch you mentioned was of a Falcon v9.2 .

[Skipjack]

The SpaceX posted capabilities says 22,200 kg to GTO with Falcon Heavy, and 8,300 kg to GTO with Falcon 9.
For LEO with an expended booster, it is saying 54,400 kg for Heavy, and 22,800 kg for 9.
So that is roughly 55 metric tons / 60 tons to LEO with a Heavy that you don't get back.

I am not sure where 550 tons comes from, that is very high (like a magnitude), unless it was a typo, and you meant 55 metric tons.

There is a conflict, but may be in the difference between recovered boosters, with a stated 5.5mT for 9 and 8mT for Heavy to GTO in fine print.

http://www.spacex.com/about/capabilities

The 550 tons to LEO for the BFR and are in line with what others have speculated. It will be a very big rocket. Of course much of it is still speculation until Musk will present it and the MCT in September.

[ladajo]

Okay. Speculated, got it.

I seem to recall Musk talking at some point about multiple LEO or L1/L2 pushes to build the Mars campaign system.
550 tons is mentally daunting to contemplate in single boost form with known capabilities. It would seem to manifest as a triple or quad pack of Saturn V class booster stacks...

SLS is targeting 130 metric tons / 150 tons, and that will be an upgraded Saturn V stack with twin pony boosters.

What do you think a 550 ton lift would look like?

[D Tibbets]

For those who missed it:
https://www.youtube.com/watch?v=xlnIT39NkVM

The significance here is that this was a GTO flight. I don't know the weight of JCSAT-14, however it would seem she was heavy given the landing kinematics (3 engine decel/landing burn).
Musk has but two boxes to check, re-flight of the LEO booster, and re-flight of the GTO booster to validate his model.

Arguably, the GTO landing indicates that he could conceivably orbit a LEO booster, and then bring it back. I wonder if that is in the cards for fun?

Umm... I'm no rocket scientist, but on the surface the first stage seems well short of orbital capacity. A speed of ~8000 Km/hr at fist stage shutdown was obtained on this latest launch. This is about 1/3rd orbital velocity for LEO. I don't know how much additional first stage fuel was used for burn back and landing, and how much deceleration was due to atmospheric reentry with associated drag, but I suspect it was much less than what would be aviable with twice the fuel used for launch. Admittedly, the flight profile and removal of the second stage and payload would reduce requirements considerably, but still...

Then there is the reentry. I don't know how much of the velocity was reduced with the boost back burn, but assuming zero would suggest a re entry speed above 8000 Km/hr. Actual was presumably well below this. Re entry from orbital speed would be ~3 times as fast or 9 times the KE so heating would be an order of magnitude greater, unless again substantial (very substantial) fuel burn deceleration would be utilized; or the rocket would need much more robust re-entry design elements.

So, I doubt first stage alone (SSTO) for the Falcon 9 is possible, and even if so, it would not survive re entry. Now, the Falcon heavy - with orbit of the first stage central core- with much modification, might be feasible though of questionable merit.

I do note that this ~ 8000 Km/hr first stage delta V at shutdown is about 1500 Km/hr faster than some LEO missions, and it still had enough fuel (barely?) to successfully land downrange on the barge- I mean the Autonomous Recovery Drone Ship. This combined with the recent announcement of a substantial increase in Falcon 9 payload to orbit (presumably near equatorial LEO) capability makes for a fluid picture (about 29,000 pound to 50,000 lb). I wonder if these numbers refer to launches from the presumptive Texas launch site as it is a little closer to the equator. What kind of performance would be possible at the French Ariane launch site?

Dan Tibbets

[Skipjack]

For those who missed it:
https://www.youtube.com/watch?v=xlnIT39NkVM

The significance here is that this was a GTO flight. I don't know the weight of JCSAT-14, however it would seem she was heavy given the landing kinematics (3 engine decel/landing burn).
Musk has but two boxes to check, re-flight of the LEO booster, and re-flight of the GTO booster to validate his model.

Arguably, the GTO landing indicates that he could conceivably orbit a LEO booster, and then bring it back. I wonder if that is in the cards for fun?

Umm... I'm no rocket scientist, but on the surface the first stage seems well short of orbital capacity. A speed of ~8000 Km/hr at fist stage shutdown was obtained on this latest launch. This is about 1/3rd orbital velocity for LEO. I don't know how much additional first stage fuel was used for burn back and landing, and how much deceleration was due to atmospheric reentry with associated drag, but I suspect it was much less than what would be aviable with twice the fuel used for launch. Admittedly, the flight profile and removal of the second stage and payload would reduce requirements considerably, but still...

Then there is the reentry. I don't know how much of the velocity was reduced with the boost back burn, but assuming zero would suggest a re entry speed above 8000 Km/hr. Actual was presumably well below this. Re entry from orbital speed would be ~3 times as fast or 9 times the KE so heating would be an order of magnitude greater, unless again substantial (very substantial) fuel burn deceleration would be utilized; or the rocket would need much more robust re-entry design elements.

So, I doubt first stage alone (SSTO) for the Falcon 9 is possible, and even if so, it would not survive re entry. Now, the Falcon heavy - with orbit of the first stage central core- with much modification, might be feasible though of questionable merit.

I do note that this ~ 8000 Km/hr first stage delta V at shutdown is about 1500 Km/hr faster than some LEO missions, and it still had enough fuel (barely?) to successfully land downrange on the barge- I mean the Autonomous Recovery Drone Ship. This combined with the recent announcement of a substantial increase in Falcon 9 payload to orbit (presumably near equatorial LEO) capability makes for a fluid picture (about 29,000 pound to 50,000 lb). I wonder if these numbers refer to launches from the presumptive Texas launch site as it is a little closer to the equator. What kind of performance would be possible at the French Ariane launch site?

Dan Tibbets

Musk stated in a tweet once that the F9 first stage could be an SSTO (without second stage and without payload, obviously).

[ladajo]

Dan,
That would be the exercise: Fly an uprated booster with no cargo to orbit, and then bring it back. I think he may just have the numbers to do it.
With cargo, he is currently separating at about 6,000 km/hr. Not a big leap for recovery engineering. The bigger question is if he drops the top part of the stack, how much DeltaV does that give him, and what fuel reserve? Separation on the JCSAT-14 flight had the 1st stage at orbital speeds with an estimated 8,300 km/hr. So in effect, he has already proven he could orbit (need about 8k), and recover from orbital speeds (8k).

See time 3:05 in the video. Note the speed.

https://www.youtube.com/watch?v=xlnIT39NkVM

[kunkmiester]

So could a "Dragon 9" be designed that would be pure shuttle? Extended first stage that hits orbit, Dragon detaches and rocket and capsule return separate (or even together!?)?

[D Tibbets]

FYI, from the video the reentry first stage velocity is ~ 1 Km/s for LEO, and ~ 2 Km/s for this mission. That is ~ 7200 Km/hr, or ~ 800-900 Km/hr decrease from peak first stage peak speed. Final speed may upon reentry may be mildly greater (?) as the stage falls towards the atmosphere, or this number may already incorporate that contribution. I think this means the first stage had a reserve of ~ 900 Km/hr worth of fuel plus the landing burn fuel. Interestingly, with ~ 3600 Km/hr LEO reentry speed, there would be about 2000 Km/hr deceleration for the boost back burn. What this means when the orbital targets and payload is factored in is any ones guess- except for SpaceX , which presumably has spreed sheets with all of these variables considered.

One consideration is that if Space X gets confidence with this hotter re entry of the first stage, they may have a little more margin with their target lift capacity to less demanding orbits for the system, while preserving high probability of first stage recovery.

Dan Tibbets

[ladajo]

Dan, don't forget the inherent object braking (those nine nice rocket nozzles on the base), in addition to the 'speed brakes' in the form of the four control tabs. All of that eats a good bit of energy, in addition to the final burn.

I really think he has margin, the question is "how much?" Maybe someone should ask him on twitter.

Good point about the landing fuel margin confidence. As they do more and more successful flights, they will build the data pile to allow for refinement of margins for sure.

[D Tibbets]

So could a "Dragon 9" be designed that would be pure shuttle? Extended first stage that hits orbit, Dragon detaches and rocket and capsule return separate (or even together!?)?

I speculate that such a two stage fully recoverable system might be possible. Basically you would need to keep the second stage attached to the space ship (like the Dragon ) and figure out how to survive reentry and landing with the compbination. The first stage would not reach orbit but be recovered.

With the updated Falcon 9 capacity of almost 50,000 lbs to LEO this seems possible.

An interesting system might marry competitors. Space X for first stage and Dream Chaser or X-37B type winged orbiter, perhaps with supplemental trunk for additional fuel. But the capacity for usefull payload (what you went to orbit for in the first place) would be limited, perhaps severely so.

A Falcon 9 follow on with methane engines or Blue Origins methane engine may make it more feasable.

E. Musk though has expressed his disdain for wings though- they are unnecessary weight. As such I imagine an evolved Falcon 9 or heavy with an enhanced Dragon 2 with larger disposable trunk for additional fuel and payload capacity/ space. The Dragon 2 already has engines and with additional fuel and efficiency the launcher and space craft is recoverable , with a relative cheap trunk disposed with each mission. With good turn around functionality such a system might provide very cheap maned access to space and also substantial payload capacity. Substituting a heavy payload upper stage for the Dragon would provide heavy lift for space station development or assembling an interplanetary manned vessel.

Dan Tibbets