The next landing of the first-stage rocket Falcon 9 begins to seem familiar and routine. One might think that the mask in the bag, and soon SpaceX with a fleet of reusable launch vehicles will become a monopolist launching services, throwing out of the market all competitors. In fact, this is an illusion. Three returning the first step - it is only the beginning of a long-same way they operate. And somewhere in the internal documents have SpaceX estimates, which shows the economic efficiency of a reusable launch vehicle. In these calculations, in any form, for sure, there are three options. These parameters are, according to their values, can make reusable Falcon 9 both effective and no. The documents SpaceX should be some preliminary assessment of these parameters. But the irony is that their real values do not know, not only we, but also the Elon Musk. Because they can only be obtained as a result of many years of operation. What are these options?
Cost mezhpoletnogo obsluzhivaniyaPervaya stage successfully village, social networking wave subsided likes the beautiful fotochki and video, and the harsh everyday engineering began. Place the stage again at the start, tuck and run tomorrow? Nope, it does not happen. Even aircraft where the aircraft several times a day up into the air, there is a set of checks that must be performed with different frequencies. A space program is still far from a resource components in thousands of hours of commercial aviation. SpaceX is not spoke in detail about the post-flight service, so you have to use a single set of available materials for reusable systems - history of the ship Space Shuttle. Thus, the shuttle on the runway meets a caravan special vehicles.
The composition of the convoy were not only obvious crane truck, lift, generator and air conditioning. Since the shuttle used explosive hydrogen gas and toxic hydrazine, in a list of special machines was a huge fan and a private car with a staff of chemical protection suits. The shuttle hitched a tractor, and hung hoses, hauled in the Orbiter Processing Facility - maintenance hangar
In this hangar were carried out following works:
- Blowing engines from accumulated moisture
- Clean cargo compartment
- Drainage hydrogen and oxygen from the fuel cell and filling them.. inert gases.
- drain the high pressure of the life support systems of gases.
- Clean water and toilets.
- Inspection and thermal protection service.
- Fixing the main engines and installation of protective covers.
- Set forests for personnel access.
- Removing and transportation maintenance of the main engines.
- Removing and transportation maintenance of shunting engines (if necessary).
- work on upgrades and modifications to the orbiter (if necessary).
But the reality turned out like this:
Instead of a relatively simple service in the style of the commercial aviation training for the new shuttle flight takes about 100 days. Such a mistake was made with the financial estimate for the maintenance of the fleet of shuttles and maintenance costs. At the end of the shuttle era for NASA budget they are more expensive than the ISS, the cost of the shuttle approaching three billion dollars in the fiscal year at 3-5 flights, which increased the cost of a flight from the official $ 450 million to almost a billion. The total cost of the project was underestimated in the three and a half times: instead of 54 billion dollars shuttle cost about 209. And the cost per flight, are counted by dividing the total cost by the number of flights amounted to half a billion dollars in 2011 prices
Optimists will say that already mentioned figures - one million dollars at the gas station and three million on mezhpoletnoe service, which should result in a saving of 30% Maybe such numbers are written in the internal documents SpaceX (let us not forget that they can now engage in dumping, to occupy a larger market share). But only practice will tell whether these figures are correct
ResursSleduyuschy question -. And how many starts can withstand the first step? Modern missiles are working on the edge of materials science capabilities when tanks excess pressure from the pressurization system (you need to fuel supplied to the engine without interruption), in engines - great temperature and pressure, and the whole rocket vibrates from the engines, turbopumps and traffic fuels through mains . And it would be wrong to think that for a rocket that goes unnoticed
Metal Fatigue -. The process of accumulation of deformation under the influence of variable loads. Despite the fact that the rocket stage operation period is usually in the range of 50 to 500 seconds to time to test the engines fatigue damage. This contributes to a high temperature in the engine and vibration
Creep metal -. Slow deformation under the influence of a constant load. Here are the main factors of high temperature (reducing the strength) and the pressure in the engine is running.
example engine damage
And here is a diagram showing the distribution of the lesions on the elements of the engine Space Shuttle SSME
46 engines were used for 135 flights shuttle (1 flightless). If counted 135 missions, each of which required 3 engine, 46 used in the amount of engines, it turns out that on average, one engine was used 8 times 8. Very interesting distribution of engines for the Missions:
Full version, larger. Non missions, disaster victims - 33 and 107.
The absolute record for the number of flights - only 19. And this engine, which is specifically designed as a reusable, and tested on 50 missions. At the same time, do not forget that the engine is in no case do not fly off 19 missions without bulkheads. On the contrary, the champion with 19 missions, refers to the first version of the engine, and then had to disassemble the motor after each flight due to problems with the destruction of the turbine blades.
It is also very interesting, as the authors of the 1996 document of the year, analyzing the experience on the use of SSME engines and techniques improve the terms of their operation, saying the relationship of engine power and its lifetime:
One option prolong engine life - reduced thrust. Basically, it is intuitively obvious - less stress, less wear
And now look at the situation with engines Merlin. For about a year optimists refer to the word mask, which are announced 40 or 50 motor cycles of use. Rocket engines - no computers, progress in them was much smaller, and you can definitely say that 50 cycles without a bulkhead of the engine - it is simply impossible. I suspect that the bulkhead is required after each mission, and, at least in some cases will require repair and replacement of defective components. This extra time and money on each of the nine engines on the first stage. We should not forget that the oxygen-kerosene engines physically less able to reuse, because unlike the oxygen-hydrogen (SSME engine shuttle), after they turbopump and the soot combustion chamber is formed, which would create additional problems. And finally, the icing on the cake - Merlin engine parameters increase over time, they begin to operate with increasing traction. This should severely reduce the life of the engine. And, despite the possibility of the launch vehicle to compensate for the failure of one of the engines, I very much doubt that, if the frequent accidents begin with engine failure, even with the successful conclusion of the payload at SpaceX there are customers who are ready to risk.
Percentage poterTot fact that the rocket Falcon 9 unmanned, adds another option, which was not in the shuttle. It must be laid a certain percentage of the loss of the first steps that will not return, for example, due to bad weather at the landing site. The situation is complicated by the fact that SpaceX will not abandon the landing on a barge in the coming years. At Cape Canaveral and Vandenberg, where there are already starting complexes SpaceX, the rocket can be launched only towards the sea. A new spaceport in Texas is also built on the beach and, theoretically, to the land planting is possible only if you run into a polar orbit (direction north), and then, if there are no settlements along the way.
SpaceX Spaceports shown in red
I deliberately did not cite statistics on the success of landing on a barge to date - it is very bad, simply because the technology was worked out. But starting this year is already worth watching, as landings are successful, and what are the reasons for the failures.
ZaklyuchenieEsche emphasize again that the exact value of the parameters mentioned above, will be available only after the experience of operating a reusable first stage which so far has never flown at SpaceX again. Also, all of the above applies to Bezos with New Shepard. Only there is solved an easier task, only one engine, the fuel (hydrogen) is better suited to the shuttle. Not surprisingly, Bezos has overtaken mask - it is one and the same rocket has flown three times
In the tag "to facilitate access to space" - reusable, air start, "big stupid media", private traders and other attempts to make space closer