Author Topic: Falcon 1 - Post Failure thread (Read 134924 times)

guidanceisgo · « **Reply #380 on:** 06/06/2006 03:56 am »

If the Air Force was looking to spread the work, they probably would not have ordered a Minotaur I to fly with less than 6 months lead. TACSAT-2 is set to launch before the end of the year. Its very possible TACSAT-2 will fly before TACSAT-1. Space News had a big article on this issue.

aero313 · « **Reply #381 on:** 06/06/2006 02:41 pm »

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guidanceisgo - 5/6/2006 11:43 PM

If the Air Force was looking to spread the work, they probably would not have ordered a Minotaur I to fly with less than 6 months lead. TACSAT-2 is set to launch before the end of the year. Its very possible TACSAT-2 will fly before TACSAT-1. Space News had a big article on this issue.

In reality, the Minotaur for TacSat-2 is the vehicle that was originally supposed to launch the NFIRE spacecraft this year. Unfortunately, NFIRE has been delayed until next year. The AF was probably facing an expensive launch delay bill from Orbital. By reassigning this Minotaur to TacSat-2 and launching this year, they avoid the delay costs (well, at least minimize them) AND get to fly the spacecraft on a proven launch vehicle.

publiusr · « **Reply #382 on:** 06/09/2006 10:43 pm »

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Jim - 2/6/2006 9:20 AM

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bad_astra - 2/6/2006 10:12 AM

I haven't seen many US Government manned orbital launches lately, either.

Knew that was coming.

But it has been doing it, it will be doing it and continue to be doing it

The system we have was determined by the people thru their elected officials.

Well put.

Chris Bergin · « **Reply #383 on:** 07/28/2006 12:07 pm »

SpaceX: Elon Musk Interview, Part I http://www.nasaspaceflight.com/content/?cid=4674

mlorrey · « **Reply #384 on:** 08/03/2006 09:34 pm »

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guidanceisgo - 4/6/2006 10:20 PM

Its interesting that Elon thumps his chest on getting a 10th bird which is just a government subsidy to fix his vehicles problems. Its also interesting to note he lost the next bunch of TACSATS to Oribital's Minotaur I. The TACSAT-2 and 3 were supposed to fly on Falcon. They did get bids to launch the TACSATS on that $100 million dollar IDIQ. I wonder if he lost on price ( no one knows what was bid on RSS, so the $6-7 million number may not stand), or on the government just not believing in Falcon anymore?

Its a matter of scheduling. Launch contracts typically have performance schedules on them, and if a provider isn't able to launch within a certain window, the client is release from the contract. Launch clients typically have backup launch providers signed in case their first choice fall through.

Cretan126 · « **Reply #385 on:** 08/03/2006 09:47 pm »

[/QUOTE] Its a matter of scheduling. Launch contracts typically have performance schedules on them, and if a provider isn't able to launch within a certain window, the client is release from the contract. Launch clients typically have backup launch providers signed in case their first choice fall through.[/QUOTE]

It wasn't a matter of SpaceX being released from the contract - the missions were never awarded to them and, therefore, there was not a launch window ever designated. You may be thinking of commercial launch contracts and EELV, but I've never seen the government carry a backup launch provider for a small launch vehicle. They may have multiple vehicles they can choose from up front - as the Air Force currently has in the Minotaur vehicles and the Responsive Small Spacelift (RSS) contracts. However, from what I've picked up, the missions went to Minotaur because it was the only vehicle judged technically capable of performing the TacSat-2 and TacSat-3 missions.

aero313 · « **Reply #386 on:** 08/03/2006 11:19 pm »

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Cretan126 - 3/8/2006 5:34 PM

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Its a matter of scheduling. Launch contracts typically have performance schedules on them, and if a provider isn't able to launch within a certain window, the client is release from the contract. Launch clients typically have backup launch providers signed in case their first choice fall through.

It wasn't a matter of SpaceX being released from the contract - the missions were never awarded to them and, therefore, there was not a launch window ever designated. You may be thinking of commercial launch contracts and EELV, but I've never seen the government carry a backup launch provider for a small launch vehicle. They may have multiple vehicles they can choose from up front - as the Air Force currently has in the Minotaur vehicles and the Responsive Small Spacelift (RSS) contracts. However, from what I've picked up, the missions went to Minotaur because it was the only vehicle judged technically capable of performing the TacSat-2 and TacSat-3 missions.

"Technically capable" of course being defined as "able to launch in the next twelve months with a high probability of success". Keep in mind that SpaceX has a bigger payload fairing and (supposedly) equal or greater performance.

guidanceisgo · « **Reply #387 on:** 08/04/2006 05:24 am »

The Minotaur vehicle for the TACSAT mission has a new 61 inch fairing. TACSAT-2 will be the first flight of this fairing.

aero313 · « **Reply #388 on:** 08/04/2006 03:20 pm »

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guidanceisgo - 4/8/2006 1:11 AM

The Minotaur vehicle for the TACSAT mission has a new 61 inch fairing. TACSAT-2 will be the first flight of this fairing.

Which is still smaller than the 68" SpaceX fairing, so payload volume and throw weight should not have been concerns in this selection. Mission success and launch schedule were almost certainly the drivers.

That 61" Minotaur fairing is the Boeing composite isogrid design that was developed under AFRL, by the way. It sure seems like an expensive way to build a fairing.

meiza · « **Reply #389 on:** 08/04/2006 03:53 pm »

Composite and isogrid. Weird.

aero313 · « **Reply #390 on:** 08/04/2006 04:36 pm »

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meiza - 4/8/2006 11:40 AM

Composite and isogrid. Weird.

Yeah. Just to clarify, these are isogrid panels laid up out of graphite. The fabrication process seem very labor and tooling intensive from what I've seen - every triangular cavity in the isogrid needs its own silicone mold, then an automated (at least, I hope it's automated) fiber placement machine routes the graphite fibers between the molds that are on top of a graphite outer skin. The real problem seems to be how you deal with the overlapping fibers at the intersections of the gridlines. Then you have to bag and autoclave cure the whole thing. It sure seems to be the answer to the question no one asked. At least with metal isogrid, you only have an NC program and a slab of aluminum. Just set it up on the mill and come back later when it's done (yes, I know that's a simplification). It would seem to me that the graphite face sheet/foam core construction that Boeing uses on the newer Delta fairings is a lot less labor intensive.

guidanceisgo · « **Reply #391 on:** 08/04/2006 11:59 pm »

aero- The spacex site shows a 60 inch diameter for the Falcon 1. Did they change it or this old info? It looks like the exterior dimension and not a payload volume.

simonbp · « **Reply #392 on:** 08/05/2006 06:03 am »

The payloard fairing on Falcon 1 is a smaller diameter than the first and second stages, so that might be the discrepency. Also, for reference, the fairing is at the moment a simple Al structure with a cork overlay on the nose (for aero thermal loads)...

Simon

aero313 · « **Reply #393 on:** 08/05/2006 03:51 pm »

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simonbp - 5/8/2006 1:50 AM

The payloard fairing on Falcon 1 is a smaller diameter than the first and second stages, so that might be the discrepency.

No, actually the discrepancy was total brain fade on my part. I just completely screwed up and was thinking about something else when I wrote that. That's what I get for trying to write a post when I'm supposed to be participating in a telecon...

As others have correctly stated, the Falcon I fairing is 60" OD with a 54" diameter payload dynamic envelope. Minotaur normally uses the 50" OD Pegasus fairing, which provides about a 46" dynamic envelope, but the 61" OD composite isogrid fairing has a somewhat larger dynamic envelope - although I can't seen to find that number at the moment. Sorry for the misinformation.

yinzer · « **Reply #394 on:** 08/05/2006 10:51 pm »

The AFRL claims that the composite isogrid fairings take 88% less time to manufacture than aluminum honeycomb ones, weigh less, and are much stiffer. They also use automated fiber placement machinery and such. It is a good point that the loads in the stiffeners are almost solely along the length, and so a good match for the anisotropy of composite structures. Also, sandwich structures have problems with moisture infiltration and pressure differentials, that are avoided in isogrids (or AGS (advanced grid-stiffened structures, which appears to be the new term of choice)).

aero313 · « **Reply #395 on:** 08/06/2006 02:48 am »

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yinzer - 5/8/2006 6:38 PM

The AFRL claims that the composite isogrid fairings take 88% less time to manufacture than aluminum honeycomb ones, weigh less, and are much stiffer.

AFRL also funded and participated in the development of that technology, so filter their press releases and fact sheets accordingly. Rare is the development program final report that says: This technology sucks.

I've personally fabricated aluminum honeycome/graphite face sheet launch vehicle structures with my own hands and I strongly question the 88% number. Does that count the time to fabricate, install, and remove all the silicone molds for each triangle in the isogrid, or just the time to actually lay down graphite? Numbers for comparison only, your mileage may vary.

braddock · « **Reply #396 on:** 08/06/2006 12:52 pm »

Part 2 of the interview is online now; this part focuses on the Falcon 9 and Merlin 1B/C development, with some interesting details:

http://nasaspaceflight.com/content/?cid=4691

The entire draft transcript, including what will run in part III, is in L2 of course.

yinzer · « **Reply #397 on:** 08/06/2006 08:02 pm »

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aero313 - 5/8/2006 7:35 PM

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yinzer - 5/8/2006 6:38 PM

The AFRL claims that the composite isogrid fairings take 88% less time to manufacture than aluminum honeycomb ones, weigh less, and are much stiffer.

AFRL also funded and participated in the development of that technology, so filter their press releases and fact sheets accordingly. Rare is the development program final report that says: This technology sucks.

I've personally fabricated aluminum honeycome/graphite face sheet launch vehicle structures with my own hands and I strongly question the 88% number. Does that count the time to fabricate, install, and remove all the silicone molds for each triangle in the isogrid, or just the time to actually lay down graphite? Numbers for comparison only, your mileage may vary.

I have no idea, just reading from the press releases. Did your honeycomb structures have to be cut in half, have separation systems installed, and then be joined back together? Did they need access doors installed in them after construction? Did they have compound curvature?

In any event, the new AFRL technique doesn't use silicone triangles for each cell in the isogrid, but machines larger grooves into hard tooling, and then uses U-shaped silicone inserts in the grooves to provide compaction. In their patent, they claim complete fabrication times of 35-40 hours including tooling production, 20-25 hours on an existing tool, both of which are substantial improvements over existing technology.

aero313 · « **Reply #398 on:** 08/06/2006 10:34 pm »

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yinzer - 6/8/2006 3:49 PM

I have no idea, just reading from the press releases. Did your honeycomb structures have to be cut in half, have separation systems installed, and then be joined back together? Did they need access doors installed in them after construction? Did they have compound curvature?

Yes, yes, and yes. The have been both biconic and ogive.

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In any event, the new AFRL technique doesn't use silicone triangles for each cell in the isogrid, but machines larger grooves into hard tooling, and then uses U-shaped silicone inserts in the grooves to provide compaction. In their patent, they claim complete fabrication times of 35-40 hours including tooling production, 20-25 hours on an existing tool, both of which are substantial improvements over existing technology.

In my experience, layup of a composite honeycomb fairing, using prepreg cloth, film adhesive between the facesheets and core, and aluminum honeycomb core requires a comparable amount of time for a structure of comparable size to the 61" fairing. Now, that doesn't include adding corefill to the honeycomb, but I'd argue that such unique local reinforcements would require additional time on the isogrid design as well. On the other hand, I'll admit that the isogrid can be somewhat automated whereas the honeycomb layup I described is done by hand - once you've made the not insignificant investment in the fiber placement machine, of course.

What I don't know is how the two fabrication techniques, when designed to the same shape and same flight loads, compare weight-wise.

braddock · « **Reply #399 on:** 08/14/2006 01:04 pm »

The Space Review is running an article about Elon Musk's presentation at the Mars Society Conference.
http://www.thespacereview.com/article/682/1

Only a couple new things there:

- Loose description of Dragon capsule solar arrays and nose cone - possibility mentioned of using the deorbit engine as a launch abort system.

-“Next year SpaceX will manufacture more rocket booster engines than the entire rest of the US industry combined,” he [Musk] claimed. He estimated they will manufacture 25–30 engines in 2007, when Falcon 9 tests are scheduled to begin, growing to 40–50 engines in 2008.

-While SpaceX develops the Merlin 1C, a kerosene/liquid oxygen engine, Musk said the company was also considering developing a liquid hydrogen/liquid oxygen upper stage engine. Such an engine would be “really critical for going beyond Earth orbit,” he said. Such an engine used on the largest version of the Falcon 9 would be able to place nearly 50 tonnes into low Earth orbit.