How cost effective will the Grasshopper really be?

[magnemoe]

I think a nice, rough test would be to launch a payload in KSP, decouple the spent stage and try to land it back to base. while this would prove very little in reality, it might make a case for how much fuel is required to land. My guess would be that the required amount of fuel would be much less than one might think and, if done correctly, might reduce operating costs.

Furthermore it is a step to fully reusable space vehicles, which I believe to be a good thing.

I tested this, 400 m/s isp is more than enough to land with in KSP. this does not have to be much fuel as you stage is almost empty. I found it far more expensive to return to launchpad from 15 km attitude with an 10 km gravity turn, however I saw some burn plans for the reusable first stage so its probably that I'm an bad pilot and used to long time turning, you want to cancel the horizontal moment as fast as possible and reverse it. Anyway they plan an new launch center in Texas, this would make the return to launchpad unneeded.

I believe the current estimate is that the first stage, not counting the fuel, makes up 70% of the total vehicle cost. If you can recover that first stage and use it immediately, that's 70% of the cost of a new vehicle you don't have to spend.

Yes probably more as second stage is smaller and only have on engine, future plans is to also make the upper stage reusable, this will be harder as it has to survive an reentry burn. This will also give a great flexibility, you can use an reusable second stage for light loads and an light one time use if you need to lift something heavy.

[pyrosheep]

everyone talks about the rocket landing at the launchpad and how that would be the fuel consuming part if the first stage participated in a gravity turn.

why not have a second landing pad in a more convenient place? would it cost so much to ferry the sub 20 Ton first stage?

[Fuzzy Dunlop]

everyone talks about the rocket landing at the launchpad and how that would be the fuel consuming part if the first stage participated in a gravity turn.

why not have a second landing pad in a more convenient place? would it cost so much to ferry the sub 20 Ton first stage?

Yeah but where?

[Themohawkninja]

Yeah but where?

It would probably have to be somewhere in the Atlantic ocean.

[Nibb31]

It would have to be between 200 or 400km of the cost of the launch site, either in the Atlantic (for a KSC launch) or in the gulf of Mexico (of they launch from the new Texas site) which is not very practical. You would need to refurbish something like an oil rig. The infrastructure cost would negate the small savings you get from reusing the first stage.

[Winter Man]

Something worth noting: Later on down the line ol' Mr. Musk wants to be able to refuel these heavy main stages (or things of equivalent size) in orbit and land them on Mars. Colonisation is his ultimate longterm goal, it's why he started the company. He's just making sure the tech exists by building his own niche on Earth and driving the cost down, so in a decade or two there's no reason not to go.

[Nibb31]

Musk is a visionary, but above all he's a successful businessman. SpaceX is a commercial venture, not a space program. They will offer rides to Mars when somebody is prepared to pay for rides to Mars.

As has been said, the goal of reusing first stages is to drive costs down. There are many very intelligent people who work in the Space industry, and there are reasons why none of them have gone with reusable rockets yet. I hope SpaceX succeeds, but there are still a lot of unknowns, both technical and economical. The technical problems are probably the easiest to solve, but it's going to be hard to pull off a commercially viable reusable vehicle.

[Apotheosist]

I think the philosophy SpaceX is taking to reusability is to make the first stage have as high a mass ratio as possible, by having very high thrust to weight engines, and lightweight, pressure stabilized, aluminium lithium tanks with flight pressure stabilization. I read on Wikipedia that for the first stage of falcon 1, only 5% of the liftoff weight is the rocket itself, and 95% is propellant. The reusability features they're adding on falcon 9 R have to be as light as possible. The landing legs are made of carbon fiber, and the pistons that actuate them use helium gas as the working fluid, all to make it super light weight. The lighter the rocket is, the higher the mass ratio, so the less fuel you need to keep on board after stage separation to propel yourself back to the launch pad. It's easier to have a higher delta v in the first stage with the small amount of leftover fuel if your stage hardly weighs anything. Adding parachutes just makes it unnecessarily heavy, means you need more fuel to fly back to pad, etc. Of course you could use only parachutes, instead of leaving some fuel in the tanks. But parachutes really suck. I mean, they give you no control of where your rocket lands, your rocket will just end up downrange, you cannot fly back to the pad. You have to land in the sea if you want a soft landing, because even if you double the size (and weight) of parachutes, they will only slow you down by a quarter (or was it one eighth?). This is due to the square/cubed nature of how parachutes work. Even landing in the sea is still quite rough, not to mention the saltwater damage. If you want to use parachutes on land, you will need airbags, which just adds more weight and complexity. Or you could use retro rockets to slow the final descent, like the Soyuz capsule....but oh wait...we don't have any fuel for retro rockets because we used up our weight budget on parachutes and airbags....remind me again why didn't we just use pure retro rocket landing in the first place?

Pure rocket propulsion reusability is better performing, not to mention the time and money needed to re pack the chutes, replace airbags, maybe haul the stage out of the sea if you chose to do that, check for saltwater corrosion, etc. Winged boosters have some of the same problem, extra weight, more complicated, need a big runway, the lower mass ratio means you cant have as much delta v to propel yourself back to launch pad. Elon knows what he is doing.

[Tankbuster32]

I actually constructed a command pod that lands using enignes, not parachutes. It needs very little fuel to land 3 kerbals safely.

[magnemoe]

Musk is a visionary, but above all he's a successful businessman. SpaceX is a commercial venture, not a space program. They will offer rides to Mars when somebody is prepared to pay for rides to Mars.

As has been said, the goal of reusing first stages is to drive costs down. There are many very intelligent people who work in the Space industry, and there are reasons why none of them have gone with reusable rockets yet. I hope SpaceX succeeds, but there are still a lot of unknowns, both technical and economical. The technical problems are probably the easiest to solve, but it's going to be hard to pull off a commercially viable reusable vehicle.

The space program started with modified ballistic rockets, main focus in the beginning was military/ political and cost was not important. Later it was an lack of funding.

Add that most who wanted to make something reusable went into the SSTO trap, an SSTO is very hard to make.

SpaceX take this in small steps as its far safer. Some of the plans back in the early 50s reminds me of spacex however they though manned stages and shuttle type landings.

You could not do grasshopper without modern control systems.

[magnemoe]

I actually constructed a command pod that lands using enignes, not parachutes. It needs very little fuel to land 3 kerbals safely.

Yes, I started to skip parachutes or more frecvently soft land an lander, the parachute is an fallback who include ditching the lander stage and just landing the pod.

[supermap]

I tried searching but i couldnt find a thing...

SpaceX states that falcon 9 launches cost around 54 million.

Any ideas how much of that cost comes in fuel... because i would guess that not that much.

Sooo how much would a reusable falcon 9 launch cost... and what other costs happen apart from fuel and manpower... because i dont think it will need the huge amount of refurbishing the shuttle needed that finally sent it to the shelves

[magnemoe]

I tried searching but i couldnt find a thing...

SpaceX states that falcon 9 launches cost around 54 million.

Any ideas how much of that cost comes in fuel... because i would guess that not that much.

Sooo how much would a reusable falcon 9 launch cost... and what other costs happen apart from fuel and manpower... because i dont think it will need the huge amount of refurbishing the shuttle needed that finally sent it to the shelves

Main cost is probably the second stage who is not recovered, at least not yet, they have plans for it. One benefit is that first and second stage use the same engine and lots of other stuff so you can use old parts and save money.

Second is checking everything and make sure it work the next time, this is that cost money on the space shuttle, you had to pull everything apart and check it but falcon 9 is simpler and this should be easier.

Last part is fuel, transport and fairings.

[Nibb31]

I tried searching but i couldnt find a thing...

SpaceX states that falcon 9 launches cost around 54 million.

Any ideas how much of that cost comes in fuel... because i would guess that not that much.

Sooo how much would a reusable falcon 9 launch cost... and what other costs happen apart from fuel and manpower... because i dont think it will need the huge amount of refurbishing the shuttle needed that finally sent it to the shelves

The largest cost in spaceflight is not the actual hardware or the propellant, it's the manpower. The salaries of those engineers and technicians who build, integrate, test, maintain, and launch that hardware, as well as the infrastructure, the administrative overhead and paperwork.

By reusing hardware, you only save on the actual material cost of building the hardware. You still need to pay for all the other tasks and process that are traditionally associated with spaceflight. The actual reduction in manpower cost is minimal because instead of paying people to build the hardware, you have to pay people to refurbish and retest the reused hardware. You don't save anything on the cost of the design, test, integration, launch phases or the administrative overhead.

On the other hand, hardware production costs can be minimized by increasing production capacity. Instead of mass producing expendable ones, which makes each individual item cheap, SpaceX plans to produce less, more complex rockets, which means that the individual cost of each one goes up.

Reusable looks technically elegant, it might not be economically viable. At least SpaceX are trying, and we will soon know for sure if it can be a viable business model.

[Apotheosist]

You really want a mass produced reusable rocket. Like airplanes are. That means you need to get the size of the rocket right. No point having one huge reusable rocket to take all cargo into space, the cost of building it would be too high. No point having millions of small reusable rockets, the payload will be too small. Must be tricky to get the right numbers. Regarding cost of fuel for the falcon 9, I remember seeing musk say it's around $200,000, which compared with the roughly $60,000,000 price of launch, that would make fuel costs be one third of one percent of the overall launch cost, which I have also seen musk say.

Edited July 21, 2013 by Apotheosist

[Nibb31]

It seems to me that a lot of peoples' reasoning has been spoilt by the Shuttle and also by Science Fiction. Apart the fact that some of them have had wings, spacecraft have very little in common with airplanes.

Airplanes are mass-produced because there is demand for people to go from point A on Earth to point B.

Reusable spacecraft can only be mass produced when there is high-enough demand for massive transport to destinations in orbit. There are no destinations in space that are reachable for the masses so there is no demand for a high flight rate. There cannot be high-enough demand unless the cost of getting into space goes down significantly. Reusable spacecraft might, or might not, be the answer to bringing the cost down. We won't know until somebody builds one and develops a viable business model for operating one. Such a business model simply does not exist yet.

Until then, the only way to reach production levels that benefit from economies of scale, is through expendable rockets.

In effect, the first spaceplane to be built will necessarily be produced in low numbers, and therefore very expensive. A reusable spacecraft will also always be more complex and more expensive than an airplane, because it operates in completely different flight domains with very different requirements and much tighter physical constraints. Spacecraft and airplanes are hardly comparable.

Edited July 23, 2013 by Nibb31

[magnemoe]

It seems to me that a lot of peoples' reasoning has been spoilt by the Shuttle and also by Science Fiction. Apart the fact that some of them have had wings, spacecraft have very little in common with airplanes.

Airplanes are mass-produced because there is demand for people to go from point A on Earth to point B.

Reusable spacecraft can only be mass produced when there is high-enough demand for massive transport to destinations in orbit. There are no destinations in space that are reachable for the masses so there is no demand for a high flight rate. There cannot be high-enough demand unless the cost of getting into space goes down significantly. Reusable spacecraft might, or might not, be the answer to bringing the cost down. We won't know until somebody builds one and develops a viable business model for operating one. Such a business model simply does not exist yet.

Until then, the only way to reach production levels that benefit from economies of scale, is through expendable rockets.

In effect, the first spaceplane to be built will necessarily be produced in low numbers, and therefore very expensive. A reusable spacecraft will also always be more complex and more expensive than an airplane, because it operates in completely different flight domains with very different requirements and much tighter physical constraints. Spacecraft and airplanes are hardly comparable.

Problem with the shuttle was that is was more expensive to launch than normal rockets. Not sure how often they could have launched it anyway even if it had be cheaper.

If access to space become far cheaper it would be far more launches, this is an overall trend for products.

Yes it would take time but bot more and heavier communication satellites would be useful. it might be interesting to put up many satellites in low orbit and have them communicate directly with each other.

next up might be manufacturing, some stuff is easier to make in zero gravity, however the cost has made this uninteresting.

In short the guy in IBM who said the world marked was only for 6 computers was right for an set price. As the price dropped the number of computers grew fast.

[Nibb31]

Yep, but for the price to drop, the market has to grow. It's a chicken and egg thing, and we still don't have a business model to generate demand for access to space.

[magnemoe]

Yep, but for the price to drop, the market has to grow. It's a chicken and egg thing, and we still don't have a business model to generate demand for access to space.

Not the way they do it with grasshopper as its an pretty cheap improvement of falcon 9. The development cost will pay back after an limited number of launches.

For an project like skylon, the lack of marked is an serious problem as it has high development cost and an line of spaceplanes who will be expensive if you only build a copple, you need an decent marked for this to be economical.

[nhnifong]

I'm still mystified about where the first stage is going to land. is it going to go mostly straight up, then turn around and come back? is it going to complete most of an orbit and come back down where it launched, or is it going to just land at the nearest convenient pad 500 km downrange?

[Nibb31]

It returns to the launch site. After separation, it performs a "toss back" burn to put itself on a ballistic trajectory that falls back to the launch site. The flight profile of the reusable first stage is more vertical than for an expendable launch in order to minimize the delta-v required for the toss back manoeuver.

Of course, this reduces performance. So does the fact that the reusable 1st stage either carries more fuel (and is heavier) or burns for a shorter time (to save some fuel for the fly back manoeuver). So does the fact that the second stage needs to compensate for the shortcomings of the 1st stage.

In the end, the reusable F9 has a payload of ~7 tons to LEO instead of ~11 tons for the expendable F9. This makes it a competitor for the Soyuz or Ariane 6 class of launchers rather than for the Atlas V/Delta IV/Ariane 5 class.

Edited July 24, 2013 by Nibb31

[Acidum]

First - first stage does not need to make gravity turn, only reach some drag-friendly height, and leave second stage make turn and orbital insertion. We are being spoiled by current launches where the goal is to leave launch site ASAP, in case of some catastrophic failure.

Second - Aeroplanes ARE good model for understanding of reusable space launching systems, as much as cars are good model for understanding of planes. Models, I say, models! Consider safety regulations in air traffic - people observed ground traffic problems and dangers, and made harsh regulations and hard technical solutions in order to bypass named problems. So, cars WERE models to planes. And now take it one step further.

And to nihilystic haters who will now say - no, they are very different because you do not have this and that, here are some more examples:

- rockets are not meant to come back to earth because of... - planes were not made to carry cargo, nor to serve as restaurants at first (imagine either of those on Wright Flyer XD ). As technology advances so do possibilities and opportunities... Why not catch the tide!

- It is far more energy consuming to fly back entire first stage of rocket...fuel for more cargo...splash it in ocean...parachutes... - People already proved that it is not that energy consuming if one uses extremely light materials. If one can land it safely and gently on a landing pad, not splash it in water at measurable part of terminal velocity, than extremely light materials can be used, which leads to less fuel for controlled landing AND more cargo to carry! Parachutes are already beaten to death on this thread, don't need to put my 2 cents too...

- 5-10% is maximum money saved... C'mon, really, 5-10% of billions and billions of any monet (dollar, euro, pound, yen...) is very much worth saving per se. And if you take under consideration that 3-4 of other fifths are actually one-time investments...

[magnemoe]

It returns to the launch site. After separation, it performs a "toss back" burn to put itself on a ballistic trajectory that falls back to the launch site. The flight profile of the reusable first stage is more vertical than for an expendable launch in order to minimize the delta-v required for the toss back manoeuver.

Of course, this reduces performance. So does the fact that the reusable 1st stage either carries more fuel (and is heavier) or burns for a shorter time (to save some fuel for the fly back manoeuver). So does the fact that the second stage needs to compensate for the shortcomings of the 1st stage.

In the end, the reusable F9 has a payload of ~7 tons to LEO instead of ~11 tons for the expendable F9. This makes it a competitor for the Soyuz or Ariane 6 class of launchers rather than for the Atlas V/Delta IV/Ariane 5 class.

Yes, however with an reusable first stage, they would pretty much own that segment, one benefit of the system is that until first stage separation it behaves like an normal falcon 9. They have done software updates on falcon 9 first stage to try to simulate soft landings, yes they will still splash down hard but they will do most of the moved for soft landings.

If something goes wrong during landing they lost the stage, this does only affect spaceX not the ones paying for the launch. Also making the expendable rocket keep the production lines up, on an later stage it might be practical to either convert some reusable to expendable or break down and use engines for upper stages.

[Sma]

Scott Manley uses a reusable rocket for his reusable space program. Though in his case the first stage gets to orbit and comes around for a landing at KSC. I'm thinking about doing the same thing...eventually, once I get a good handle on my kethane program and have kethane ops on Kerbin. Then instead of building complete rockets in the VAB, I could just build upper stages, pick them up from the launch pad with either some type of crane, or maybe a skycrane, then attach them to the reusable launcher after it's been refueled.

Totally random idea...has anyone ever tried a zipline from the VAB to the launch pad, or any of the other buildings?

As far as the launch center in Texas goes, I could be wrong, as I haven't read much about it lately, but I don't think they're launching from Texas. I think it could be more of a control center, similar to Houston. Part of the reason is if something were to go wrong during a launch, it could scatter debris across FL......Ok, NM, I looked it up http://en.wikipedia.org/wiki/SpaceX_private_launch_site It's right on the edge of the US/Mexico border apparently. I live on the west coast of FL, it would be interesting to see rocket launches coming from a different angle.

[magnemoe]

Scott Manley uses a reusable rocket for his reusable space program. Though in his case the first stage gets to orbit and comes around for a landing at KSC. I'm thinking about doing the same thing...eventually, once I get a good handle on my kethane program and have kethane ops on Kerbin. Then instead of building complete rockets in the VAB, I could just build upper stages, pick them up from the launch pad with either some type of crane, or maybe a skycrane, then attach them to the reusable launcher after it's been refueled.

Totally random idea...has anyone ever tried a zipline from the VAB to the launch pad, or any of the other buildings?

As far as the launch center in Texas goes, I could be wrong, as I haven't read much about it lately, but I don't think they're launching from Texas. I think it could be more of a control center, similar to Houston. Part of the reason is if something were to go wrong during a launch, it could scatter debris across FL......Ok, NM, I looked it up http://en.wikipedia.org/wiki/SpaceX_private_launch_site It's right on the edge of the US/Mexico border apparently. I live on the west coast of FL, it would be interesting to see rocket launches coming from a different angle.

Benefit of an Texas launch is that you launch over the gulf, you just do an smaller sideway connection to land somewhere in the US. This will be required for an future falcon heavy reusable main stage who will reach larger height than the one in falcon 9.

Scott's program was restricted in that he wanted to do an reusable program based on KSP premises: only control one ship in the atmosphere.

I used an main stage and two boosters with cross-feed in my reuseable, here I dropped the boosters at 10 km just before gravity turn, the main stage reached low orbit and released the payload before landing. The boosters was lost, they was however equiped with probe, rcs and extra fuel so I could switch to one of them and land them, in fact using mechjeb and setting an landing point just outside the spaceport they could land automatically however it was just an simulated system.