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# Congratulations to Space X

## Congratulations to Space X

(OP)
Well Space X did it. Launching 11 satellites and recovering the booster.
Congratulations to all. This is a long movie 55 Min's, booster recovery is about halfway through.
If you can't watch this at work , copy the link and watch it at home.
History in the making.
B.E.

You are judged not by what you know, but by what you can do.

### RE: Congratulations to Space X

Nice work SpaceX. Definitely a step forward in space launch technology. Maybe not quite as historic an event as some are making it out to be though. Multiple satellites have be successfully placed in orbit using a single launcher before. Several entire space shuttle systems, except for the external propellant tank, were successfully re-used multiple times. Shuttle mission STS-51 actually deployed two satellites, then retrieved two other satellites and returned them safely back to earth. And last month Blue Origin flew their re-usable launcher to 100km and landed it safely back at their facility in Texas.

SpaceX succeeded at landing the booster stage after a couple previous failed attempts, which is not that bad of a record for such a difficult task. Unfortunately, they announced today that the recovered Falcon 9 booster stage will not be flown again.

In my opinion, SpaceX's real achievement is setting the bar a bit higher for everyone else in the industry. Hopefully, the result will eventually be a commercial space launch industry where private sector companies can compete fairly for business. Just like most other industries, fair and open business competition will spur continuous improvements in technology and lower costs.

### RE: Congratulations to Space X

Obviously the most interesting bit, by far, is the landing of the first stage. Obviously.

Link seems to say that they're planning to keep it, presumably as a historical artifact. No damage mentioned. What's the 'unfortunately' part of that?

### RE: Congratulations to Space X

Woohoo
That was fun. Thanks for posting BE.

STF

### RE: Congratulations to Space X

agree nice job, but I was wondering how much payload they surrender to get the return fuel ? Is the rocket's fuel load about double what it needs for launching ? I get it that overall this may be cheaper than building single use rockets. I wonder what the rocket could do as a single use ? (ie how much more payload could it lift if it didn't need to save fuel for the return ?) I wonder how much effort it'll take to refurbish the rocket ? (remember the space shuttle ...)

### RE: Congratulations to Space X

I imagine the fuel needed to neutralize velocity and send it toward the landing pad is quite small since it only has to push a near-empty first stage booster. The fuel required to launch must carry the weight of a full booster and the payload and whatever second/third stages are present for that particular configuration. It does burden the fuel requirements of the initial launch, obviously, but I would be surprised if it halved the payload capacity or anything so dramatic.

### RE: Congratulations to Space X

"Is the rocket's fuel load about double what it needs for launching ?"

The first stage is typically mostly fuel and oxidizer in terms of mass, so by the time it gets to the initial MECO and turns around, it must be much less mass than it had at launch. Therefore it would need only a fraction of the fuel and oxidizer to stop, reverse and land.

It's a bit non-intuitive; but after some thought, it's obviously not double. It's likely a surprisingly-small fraction. I have no idea how much; but I'll happily guess about 15%.

Edit: "how much payload they surrender to get the return fuel ?"

Information says there is a 30% reduction in payload to orbit to provide the extra fuel and equipment to land on its tail. Since the fuel and oxidizer mass dominates over the payload-to-orbit mass, the extra fuel must be quite a small fraction.

More: The fuel and oxidizer reportedly cost on the order of $250k on the$60M to \$100M launch price. Less than 1%.

### RE: Congratulations to Space X

#### Quote (VE1BLL)

Link seems to say that they're planning to keep it, presumably as a historical artifact. No damage mentioned. What's the 'unfortunately' part of that?

The whole point of the concept is to re-use the booster stage for launching payloads, not to create museum exhibits. The truly historic achievement would be demonstrating re-usability by launching and safely recovering the same booster stage more than once.

rb1957 also makes a very good point about how incredibly difficult it is to design liquid fuel engines that are truly capable for reuse multiple times without costly servicing and refurbishment work between flights. Liquid fuel rocket engines are very, very high-performance devices. The shuttle RS-25 liquid main engines were "re-usable". But they required extensive servicing and inspection after each flight, and were overhauled after just a few flights. Going forward it will be interesting to see how well the Falcon 9 booster structure and engines hold up in service.

### RE: Congratulations to Space X

it'd be interesting to compare the Falcon with a similar sized rocket ... compare payloads for the same launch weight, compare launch weights for the same payload. Weight is incredibly important to rockets and allmost the fuel used for the return could have been payload. Another lost payload is in the higher weight of the motors and machinery and structure to allow the rocket to be reused (ie the empty weight of the Falcon should be considerably higher than a single use rocket). And to cost a reusable rocket as the price of the fuel way underestimates the servicing costs to return the rocket to operations.

still it was cool to see. landing on the barge would have been way cooler ! (but, yes, barge US after last near-miss)

### RE: Congratulations to Space X

I mentioned the stated cost of fuel for context, not to imply that a future SpaceX launch would be 99+% cheaper (clearly a ridiculous interpretation).

As long as they're cheaper than the other guys, they win. They're already cheaper...

Re-usability doesn't need to be ideal to further reduce costs. If re-usability increases costs (which seems very unlikely), then they'll simply stop doing it. Now that would be unfortunate.

The stated impact on payload [mass] for the 'return to ground' is -30%. This figure is reportedly a quote from Musk.

They have have a triple version in their plans. Three '1st' stages strapped together. So, in the long run, they'll be able to launch any payload you want, hopefully for significantly less than today's cost.

It's all very interesting.

Season's Greetings.

### RE: Congratulations to Space X

#### Quote:

rb1957: it'd be interesting to compare the Falcon with a similar sized rocket ...

I agree.
Stats for specific impulse (in vacuum, mostly)

Solid fuels:
80s Estes B6 Motor (sea level, of course!)
250s Space Ship One
269s Space Shuttle solid Booster

Liquid fuels:
273s Gemini launcher
304s F-1 (Saturn V motor)
311s SpaceX Merlin
440s Ariane 5 (EPC H173)
453s Space Shuttle Main Engine

So... the Merlin is fair in performance, for a liquid-fueled engine, but doesn't compare to other modern heavy-lifters.
I don't think the SpaceX advantage is with spectacular performance. I think there's something else in their secret sauce.

How many of us have encountered a "point of diminishing returns"? For a doubling of cost, a consequent doubling of performance cannot be gained? My theory is that SpaceX has aimed for a cost-effective middle, by plotting data like I have on one axis, and mission cost on the other axis. Then they picked the point on the curve where the cost hasn't shot up yet, but the performance is good enough to do the job. Which is exactly what a commercial space venture should do, and what no government-funded program would ever do.

STF

### RE: Congratulations to Space X

One reason for lower Isp of the Merlin is use of RP-1 (kerosene) fuel instead of LH2.

A launcher with similar payload capacity to the Falcon 9 is the Delta IV Med+, and they make for a very interesting comparison. The Falcon 9 1st stage has nine Merlin 1 engines using RP-1/LOx. The Delta IV Med+ 1st stage has a single RS-68 engine using LH2/LOx. The Delta IV was not intended to be man-rated, while I believe the Falcon 9 is. One would assume that SpaceX chose to trade weight for reliability by using nine engines instead of one. Also RP-1 fuel has some advantages over LH2 in terms of safety and ease of handling. One goal of the RS-68 design was lowering cost by reduced parts count and simplified design. The RS-68 produces more thrust than the shuttle RS-25 main engine, yet has less than 1/3 the number of parts. The RS-68 also uses an ablative nozzle rather than a regeneratively cooled nozzle.

One hurdle I can see that SpaceX will need to overcome with re-using a booster stage is convincing insurance underwriters that this booster on subsequent flights is as reliable as a new expendable booster. A large commercial satellite might be insured against loss due to launch failure for a couple hundred million dollars, and the cost for that insurance coverage is significant.

### RE: Congratulations to Space X

SpaceX has absolutely gone for the 'cost effective' if their statements of goals and accomplishments are to believed. They are not going for the efficiency of unit of mass per unit of fuel but rather unit of mass per dollar. They are trying to get into the Taxi business for the ISS and other LEO operations. At least for now.

In regards to the drone barge landing, I have heard that the only reason SpaceX was even attempting the barge landing was to sate FAA requirements. I was told (this is mostly through aerospace engineer rumor mill afaik so far) that the FAA would not grant permission to attempt the landing over land until they've proven the reliability of their landing targeting. They never had to do it /safely/ so to speak. That would have been gravy. They had to prove their precision before the FAA would let them try it on land.

This is the only article I could dig up that seemed to remotely substantiate the claim: http://www.americaspace.com/?p=89127

But they don't say it specifically, but merely mention that the barge landings were only being done until the FAA approves the onshore landings.

Can anyone verify that rumor I've heard?

### RE: Congratulations to Space X

Thanks for the article link. When launching east from the cape the FAA is responsible for clearing the airspace within the rockets flight path, but I believe the USCG makes sure the ocean surface under the flight path is also kept clear.

The best part of that article was where it said the location SpaceX landed the Falcon 9 booster was re-named from Launch Complex 13 (LC-13) to Landing Zone 1 (LZ-1). The success rate at LZ-1 is currently 100%.

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