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SpaceX's 64-ton Falcon Heavy rocket is ready for launch

By Greg S ยท 15 replies
Feb 5, 2018
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  1. Despite problems with the previous launch of a classified payload designed by Northrop Grumman, SpaceX has put that in the past and is readying the world's largest rocket ever built. The Falcon Heavy is set for launch on February 6 at 1:30 PM EST with a window extending to 4 PM.

    Composed of 27 Merlin engines, the Falcon Heavy tips the scales at around 141,000 pounds. All of those engines present points of possible failure, but together generate over 5 million pounds of thrust during liftoff. Regardless of being one the most massive rockets ever built, the Falcon Heavy is able to carry more the twice the payload of any other currently available launch vehicles.

    The only real point of comparison to the Falcon Heavy is the Russian-built N1 moon rocket that had 30 stage one engines. However, given that the Soviet Union failed to ever successfully launch an N1 rocket and the last attempt took place in 1972, SpaceX holds many modern advantages.

    Since this will be the first launch of a Falcon Heavy, a dummy payload of a Tesla Roadster will be on board. The 2,760 pound payload will be launched towards the orbit of Mars and is expected to end up in orbit around the sun if all goes according to plan.

    At maximum load, the Falcon Heavy can carry almost a one-to-one ratio of payload capacity. Up to 140,660 pounds of material can be put into low Earth orbit, although that number shrinks to 37,040 lbs for a trip to Mars and 7,720 lbs when traveling to Pluto.

    As far as space travel goes, Falcon Heavy missions are relatively cheap given what they can hopefully accomplish. Mission pricing starts at as little as $90 million.

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  2. senketsu

    senketsu TS Guru Posts: 710   +480

    During the "space race" I recall a problem was developing a rocket that could lift the sufficient payload. Easiest solution was to add more engines, but it was found to be extremely difficult to get that many engines working properly. Seems of note that the Saturn V had only 5 main engines while the Soviet N1 had 30 engines by comparison in first booster. It was apparently an extreme engineering challenge to make engines like the Saturn V's F1 engine, so hard the Soviet's failed.
    So 27 engines is a few, but I hope they can make it work.
     
  3. wiyosaya

    wiyosaya TS Evangelist Posts: 2,919   +1,432

    You are absolutely correct on the Saturn V's five, Rocketdyne F1 main engines. Each engine developed approximately 1.5 Million pounds of thrust making the total for the Saturn V approximately 7.5 million pounds of thrust, or 1.5 times the thrust of "The Falcon Heavy". https://en.wikipedia.org/wiki/Rocketdyne_F-1 Testing of the F1 broke windows miles away. There is an excellent series called "Moon Machines" that talks of some of the problems in developing the F1. There was a problem with resonance that had to be solved. I highly suggest watching Moon Machines as one can get an idea of the technological marvels that were developed during the Apollo program - a program that required some 500,000 people..
     
    senketsu likes this.
  4. mbrowne5061

    mbrowne5061 TS Evangelist Posts: 986   +508

    It was the fuel, not the engines, that posed the problem. The soviets never figured out how to work with cryogenic hydrogen in the same system as cryogenic oxygen. Both extremely cold, but still hundreds of degrees of difference between the two. Thermally insulating the two from one another until just before being mixed in the reaction chamber is extremely tricky. Somewhat amusingly, it was the surfers of Southern California who saved us from a similar fate as the Soviets: they knew how to work with fiberglass to create lightweight and uniquely shaped geometries. It was their work that allowed the US to put liquid hydrogen and liquid oxygen into two tanks that shared a bulkhead. Without liquid hydrogen, you're forced to use a more massive fuel on the upper stages, like kerosene. While you want something like kerosene for your first stage (reactive, and lots of mass you dump to appease the laws of Newton), you want your fuel as light as possible on the upper stages, or you end up having to produce a truly a massive rocket (see the N1). All math for determining energy necessary to make orbit starts with the payload you have and the orbit you want; then you literally work your way down to earth's surface.

    The soviets transporting their engines by railroad didn't help much either.

    Whether SpaceX will fair much better is hard to say, but given their track record with their Merlin 1D and the number of them they are putting on this one vehicle, I put it at 1/500 odds that the first launch explodes during the first stages, and 1/100 that the first stage of one of their first dozen Falcon Heavy launches explodes.
     
    wiyosaya and senketsu like this.
  5. GeforcerFX

    GeforcerFX TS Evangelist Posts: 799   +326

    Taking into account that two of these boosters have flown already, if everything goes to plan tomorrow, seamless launch, landing all 3 stages and the payload makes out on it's journey, that will be a major accomplishment, especially when you remember this is a private company.
     
    Last edited: Feb 5, 2018
    Flebbert likes this.
  6. wiyosaya

    wiyosaya TS Evangelist Posts: 2,919   +1,432

    There is government money funding this, and my bet is that there is government expertise, probably from NASA, helping out. There are government programs such as SATOP (http://www.spacetechsolutions.com/), intended to provide expertise; however, my bet is that if SpaceX started out with SATOP, they are now paying for the expertise.
     
  7. Joe Blow

    Joe Blow TS Addict Posts: 216   +74

    So Space-X is now one of those disgusting government contractors. And a trip to Mars? That's a laugh. We haven't even put humans on the Moon yet. At least, not with Apollo.
     
    wiyosaya likes this.
  8. mbrowne5061

    mbrowne5061 TS Evangelist Posts: 986   +508

    Musk and the rest of SpaceX approached the Falcon heavy with the same mind set, and realized how wrong they were. The dynamics of the problem change completely. From the air flow around the rocket as it passes from subsonic, to trans, to super, to hypersonic flows, to when these changes in airflow occur, to the internal vibrations and harmonics. Everything changes when you get into rockets this large. This was why the Falcon Heavy took so long to produce, and why Musk himself has been tempering expectations of its success with Tweets about them (SpaceX and himself) having underestimated the problem.

    If building bigger rockets was as simple as strapping together a bunch of smaller rockets, we would have started doing it a long time ago.
     
    wiyosaya likes this.
  9. GeforcerFX

    GeforcerFX TS Evangelist Posts: 799   +326

    Well I mean we did build Big rocket's a long time ago :D, we are now just returning to it, but with a much tighter budget on our minds.
     
  10. wiyosaya

    wiyosaya TS Evangelist Posts: 2,919   +1,432

    From my experience, fast, cheap, and easy is a risky way to go. Musk has been quoted as saying that if it clears the launch tower, he will consider it a success. As I see it, if it does clear the launch tower and then fails, they have a long way to go.
     
  11. mbrowne5061

    mbrowne5061 TS Evangelist Posts: 986   +508

    You're right, we did used to build big rockets. We still don't. The Falcon Heavy is just three Falcon 9s "stapled" together. We won't have another, true super-heavy lift rocket until the Space Launch System comes online in a few years. My guess, you'll see SLS used for missions with human payloads, or those missions that require the extra Delta-V offered by the SLS over the FH (for equal payload masses), and the FH will function as an automated cargo tuck to space. The FH will also almost certainly be replaced by the BFR when that shows up, they'll only roll out the FH when a customer needs the lift of the FH, but not as much as a BFR will provide (a narrow sliver, in terms of payloads)

    It was very interesting to see them throttle the boosters down a back up as they crossed through supersonic flow into hypersonic. Its clever way to get around the stresses air drag on the boosters would put on the central core, but leaves a lot of things to go wrong. They may not throttle down, may not throttle back up, throttle differently at either point, etc. For this reason, I doubt the Falcon Heavy will ever be certified for human flight, not unless they build one impressive abort system that is able to function as the vehicle passes from supersonic flow to hypersonic flow profiles.
     
  12. GeforcerFX

    GeforcerFX TS Evangelist Posts: 799   +326

    SLS won't be up to Saturn V performance until the late 2020's early 2030's, block 1 is going to have pretty much the same performance as the Falcon Heavy for LEO and a bit better for lunar shots, but at 2-3 times the cost of the falcon heavy. I like where SLS is taking us but I think it's to wasteful to be a valid rocket in the 2030's, throwing away the boosters, throwing away the engines. It's going to be a bargain at $500-600 million a launch compared to the Delta IV heavy, but both of them compared to the falcon heavy or even the falcon 9 are outrageously expensive.
     
  13. mbrowne5061

    mbrowne5061 TS Evangelist Posts: 986   +508

    The Falcon heavy though, because of its unique throttle-down-throttle-up profile during ascent (to compensate for a weaker mechanical design of the overall superstructure), is unlikely to be approved for human flight any time soon. That leaves the SLS for human flight to the moon.

    The Block 1 configuration of the SLS will already have a 50% payload advantage over the Falcon Heavy, which is more than enough for Lunar missions. The Saturn V was so large because the technology it needed to boost was heavier, extra fuel was brought for emergencies, and NASA had dreams of using it to boost more adventurous missions to the moon with later configurations (that never materialized)
     
  14. GeforcerFX

    GeforcerFX TS Evangelist Posts: 799   +326

    Didn't the shuttle do the same thing? Throttled engines back during Max Q. Is there some sort of acceleration issue? The dragon capsule has already shown it's launch escape capability, which if I remember right can be used all the way up to 160,000ft. B ut it doesn't matter Musk already said they arn't using heavy for lunar missions. I could see them using the heavy to put a transport vehicle into LEO then shuttling people up with the Falcon 9.
    Block 1 SLS can do 70 metric tons to LEO current Falcon heavy is 63, from there NASA says moon payload, SpaceX says mars payload, they have different goals it would seem :D. By the time they get block 1B running or block 2, there should be a upgraded falcon 9 and falcon heavy and BFR should be doing initial testing.
     
    Last edited: Feb 8, 2018
  15. mbrowne5061

    mbrowne5061 TS Evangelist Posts: 986   +508

    The shuttle waited to throttle its engines up until after max-Q. The SRBs provided most of the life through max-Q, and the Shuttle engines were ignited on the pad out of an abundance of caution. The SRBs stayed at full "throttle", given that they can only be "throttled" by playing with grain structure and mixture during manufacturing and fuel loading. But they're a solid fuel, once lit, they are going to stay lit.

    Escaping a failing launch isn't just an acceleration issue, its punching through the shockwaves of supersonic and transonic flow, and then surviving the deceleration as you pass back into subsonic territory - all while something is going catastrophically wrong. But its not the act of escaping that NASA will be worried about, but the likelihood of needing to escape. Throttling down and then back up with liquid fueled engines will spook them enough when evaluating it for manned launches. What if they don't throttle dow? What if they don't throttle back up? what is they don't stop throttling back up? What if they throttle up too soon, too late, too quickly, too slowly? What if the throttling breaks something? These are all questions NASA and the FAA are going to want answers to. They are going to pay it very close attention to performance, over these next few launches - and SpaceX has handicapped themselves by re-using their rockets. With the SLS, one-and-done, they is no rocket to inspect for damage and begin to asses MTFBs. With The Falcon line, there are. SpaceX is going to have to separate what is expected wear and tear for an average F9 flight, and what is caused by the larger forces of a F9 booster being put into an FH configuration.

    Meanwhile, the SLS will show up on the scene pretty much already cleared for human launch. EM-1 will be unmanned, but EM-2 will almost certainly be manned. If FH and Dragon get cleared for human launches before SLS and Orion, I'll be stunned. I also wouldn't be surprised if Musk does the math and just decides to skip getting the FH cleared for manned missions and go straight to getting BFR cleared, since the FH will have better returns on payload missions. Who is paying to send men to the moon, and are they paying enough to warrant all the expensive of getting it cleared for human missions - when BFR will be a more capable platform with (likely) few risks to have to explain and justify to NASA and the FAA?

    Once you get out of Earth's gravitational pull, a given rocket will have 'similar' payload capacities to most destinations - depending on velocity. So its not surprising that they have similar launch capacities, but going towards different stated definitions. Boeing states the Moon to be conservative, SpaceX states Mars to be aspirational. In reality, they both probably lift similar amounts to the same destinations. Going in towards the sun is a different story; always more expensive kg-for-kg than going away from the sun. They might begin to differ in payload capacity and capability if someone wants to use them for a Venus, Mercury, or Sol mission.
     
  16. GeforcerFX

    GeforcerFX TS Evangelist Posts: 799   +326

    What about Saturn V, all liquid engines and it throttled throughout the launch, and it was 3 stages. But again FH will not carry people, between the vast improvements to F9's payload over it's life and the fast track development for BFR they aren't even trying to get it certified for human launches now, Elon said it in a interview on Feb 5th before the FH launch.
     

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