SpaceX Updates (Thread 4): F9, FH & Dragon

[DocM]

Note the tumble. Its intentional to test deployment under a very abnormal situation. The drogue mortar has also been moved from the service bay near the bottom to the top near the docking adapter to make more room for the SuperDraco thrusters and their tanks.

[SarK0Y]

if capsule was flip-flopping that way in real flight, the would be no room to survive because initial velocity of vehicle (in real descending) to shoot drogue out is much greater. 

[DocM]

That rotation is a few G's, which pilots and parachute deployment systems somehow regularly survive.

[SarK0Y]

actually, there is rotation around longitudinal axis (in normal flight) + such rolling can & better off be stopped before *chutting.

[DocM]

Well, then you should file consulting papers with NASA so you can inform them of the error of their ways - a similar smart release algorithm has been in the spec for the Orion spacecraft since 2009.

[SarK0Y]

there isn't mistake to inform about: for initial test, such flip-flopping ain't big deal -- it's even good to stress chutes as much as possible. For re-entry phase, Yes -- such dances cannot be acceptable. By the way, that  whirling is possible in powered-landing scheme because thrusters have a probability to malfunction even higher than chutes.

[DocM]

....thrusters have a probability to malfunction even higher than chutes..

The reverse is true.

Parachutes are complex with numerous failure modes. Hypergolic thusters are inherently extremely reliable, which is why they're still in use after almost 70 years.

With parachutes the mortar can fail to fire, the deployment controller can fail, the altimeter or inertial sensors can fail, drogues can fail to deploy and/or tangle, the mains can fail to deploy and/or tangle, ANY of the parachutes or drogues can fail to inflate or shred, etc.

For a parachute to fail any one of several things in a sequence can bring down the whole thing. Having 3 redundant parachutes can help, but on a bad day they can also take each other out.

Failure examples: Venera 7, Soyuz 7K-OK (Vladimir Komarov death), Genesis spacecraft, 2008 Orion parachute test, etc. etc. etc.

Hypergolic thrusters use a fuel and oxidizer that ignite on contact, so no igniter is needed, and there are no pumps as both tanks are gas pressurized, with backups.

All that's needed for thrusters to work is for a release valve set to open, and there is not only a backup flow path & valve set (or several) but in DragonRider the avionics computer that controls the valves is quad-redundant.

For thrusters to totally fail a lot of things have to break at once, and in the case of SuperDtaco's even they are redundant - DragonRider can lose 1-2 thrusters and still land or, at worst, deploy the parachutes.

[FloatingFatMan]

Hey Doc.. you're doing what you advised me not to do! Silly. :p

[DocM]

Partly, but it had to be said.

Channel re-closed.

[TrevorLahey]

Partly, but it had to be said.

Channel re-closed.

It helps me understand more when you answer him sometimes.

[DocM]

That's why I did - this time.

BTW - the 8 SuperDraco's are arranged in 4 pairs and only need about 20-25% thrust to land. Lose one in a pair, throttle up its mate.

[SarK0Y]

i'd like to see practical release of that scheme. my doubts were explained many times..

[DocM]

A lot of this article is a rehash of the SES-8 launch attempts and launch, but the last 2 sections about the relationship between SpaceX and satellite builder SES are quite interesting....especially the last paragraph if an SES >--> SpaceX tech transfer takes place.

http://www.satellitetoday.com/publications/2014/01/21/ses-ans-spacex-shaking-the-industry-to-its-roots/

SES and SpaceX: Shaking the Industry to its Roots

>

>(Long rehash)

>

The Beginning of a Long-Term Relationship

Weve had extraordinary access to the analysis work that has been done, Halliwell said. Due to ITAR restrictions only U.S. citizens from SES team were allowed to gain insights of the launch vehicle. They could not tell me the outcome of the meeting, all they could do was come with a recommendation of yes, were good to go or no, were not good to go; they couldnt give me the details, he says adding that, SES team of U.S. citizens were embedded together with the SpaceX propulsion team and its been able to retire an awful lot of risk associated with this and its given us a real feel good character, he said. We crawled all over [the Falcon 9 v1.1], believe me, and were happy.

This close relationship between SES and SpaceX was key to the success of this mission as it allowed both teams to collaborate and make sure that every detail of the process met the requirements of both parties.

What is interesting with SpaceX, whenever they had a problem, we had quite a lot of visibility into it. Weve had the opportunity to be able to work together with them, which is relatively unusual, he added. Its a long-term relationship with these guys, Halliwell added.

Both Halliwell and Starkovs emphasized that their trust was based on the open relationship with SpaceX, which allow them to experience first hand, all the efforts the team made.

Were very appreciative that SES would place their faith on SpaceX. One thing I can say with certainty is that weve done everything we could possibly think of to maximize the probability of success for the mission, Musk said before the first launch attempt. The policy of SpaceX is, right up until the launch takes place, if anyone has any unresolved concerns, they can email me directly, and well put a hold on the launch and resolve whatever that issue might be.

One Launch, Many Milestones

The SES 8 launch was important to SpaceX not only because it was its first commercial satellite launch to geosynchronous orbit, opening a flurry of new business, but also because it counted toward the certification process for the U.S. Air Forces Evolved Expendable Launch Vehicle-class (EELV) program, according to Shotwell. Obtaining this certification will allow SpaceX to compete with United Launch Alliance (ULA) for national security payload launch contracts.

A successful launch with SpaceX potentially opens up a number of new possibilities for SES also. The big push that were looking for at the moment is electrical propulsion, thats the big game changer again, Halliwell said. Youll be able to launch far more complicated satellites with a much more smaller mass and thats when SpaceX really starts to come into its own.

[SarK0Y]

 

Parachutes are complex with numerous failure modes. Hypergolic thusters are inherently extremely reliable, which is why they're still in use after almost 70 years.

DocM, hypergolics haven't been used for powered - landing from orbit onto Earth. if you burn fuel all-way from orbit, there will be painful penalty by extra weight; if you run thrusters at the very ground (at the terminal velocity), you get too small room for backup measures. + needless to mention, it needs terminal velocity as low as possible to save propellant, only way to do that is semi-chute scheme. I.e. drogue reduces terminal velocity. perhaps semi-chutting will be quite economically reasonable solution, but pure power-landing approach looks like fantasy -- there require much more efficient engines.

[DocM]

IEEE Spectrum: "Brandon Pearce's avionics guide to SpaceX rockets

Meet the man who keeps SpaceX?s rockets on track"

http://spectrum.ieee.org/geek-life/profiles/brandon-pearces-avionics-guide-spacex-rockets

[SarK0Y]

any launches for February?

[Beittil]

You know you can find that information online easily right? Then you could have seen there was one scheduled for the 22nd, but it had been moved to March 1st!

Seriously... Spaceflightnow.com... Its all there!

[SarK0Y]

Beittil,

the more sources, the more opportunity to gain first-hand info ;) + that flight for nasa, but i meant commercial ones.

[DocM]

Orbcomm OG2, which will launch 8 commsats at once with secondary payloads. Date to be determined.

The March 1 CRS-3 date is a one day opportunity because of the departure of Progress from ISS and other Visiting Vehicle (VV) schedule events. The ISS VV schedule for March is packed, so if March 1 can't be made ~March 22 is the next slot.

It's theoretically possible if there's a VV induced delay of CRS-3 they could launch Orbcomm OG2 first, but don't bet on it.

[SarK0Y]

Thanks for info, DocM.

[flyingskippy]

With DOD reviewing the Falcon 9, why are they signing a deal for 36 cores from ULA through 2020?

[DocM]

Those launches have to be booked years in advance.

Many launches now being booked are for DoD payloads larger than F9 can currently handle - basically Atlas V 552 and Delta IV Heavy class - plus its certification review isn't finished. Falcon Heavy would be the SpaceX option for those, but it's first DoD certification flight isn't until 2015 and its review may not finish until 2016/17. Neither can be booked until certified. Now add the schedulig gaps.

[flyingskippy]

Those launches have to be booked years in advance and many are for DoD payloads larger than F9 can currently handle - plus its certification review isnt finished. FH's first certification flight isn't until 2015. Neither can be booked until certified.

Thanks Doc. I was reading some of the comments on the article at spaceflightnow.com and the ULA people were throwing it out as a win against SpaceX. I guess they didn't want to point out that the payloads would require the FH.

[DocM]

Yeah, the ULA guys are still stinging about SpaceX getting pad 39A and the 2 GTO launches. So are Arianespace and ILS. Falcon Heavy will be a big headache for all of them, as will its follow-on.

[DocM]

Elon Musk on CBS NEWS.

What's new is the lunar trips and confirmation that their large core will be massive. Rumors run 180-200+ metric tons to LEO with reusability, perhaps 300 metric tons as an expendable.

We know the big (650,000-690,000 lbf) Raptor staged combustion methane engines (booster and vacuum) components start tests at NASA Stennis early this year. Raptors could easily power the beast.

Summary.

1) though he's not very interested in the Moon, after getting Commercial Crew they may do a fly-circumnavigation of and/or landing on the Moon to prove the capability.

2) Mars Colonial Transport will be a rocket on a scale than has ever been done before, would make the Saturn V look small and it would have to launch very frequently.

3) mid-2020's for the first crew to Mars