My reusable launch system finances

[nhnifong]

I am working on the following two reusable launchers

Overall the rocket has a slightly higher operational cost but It is lower risk. I'd like to calculate the exact landing risk for the plane that makes the operational cost break-even with the rocket.

Both launchers are designed to put a 38.8t payload costing 12k into LKO.

Below, the payload cost is deducted from the operational cost of the launch to make comparing launchers simpler.

Rocket:

Up-front launch cost: 96,547

Perfect recovery revenue: 69,152

Operational cost: 27,395

Spaceplane:

Up-front launch cost: 223,234

Perfect recovery revenue: 217,534

Operational cost: 5,700

And the risks:

Due to limited range control on the recovery of the rocket, (I can't hit KSC on the nose) I can only expect about 90% of the perfect recovery cost.

For the plane What is the probability of crash that will make the operational cost break even with the rocket?

[GoSlash27]

nhnifong,

That really depends on the pilot. How good are you at getting a spaceplane back on the runway?

If you can do it every time, then there's no risk.

Also, are you sure that spaceplane can survive the trip?

Best,

-Slashy

Edited July 18, 2015 by GoSlash27

[nhnifong]

Well, usually I get it every time, but this plane is difficult. So far my record sucks: 3 successful landings out of 5

[GoSlash27]

NVM, ninja'd

Okay then, you're batting .600.

Were the 2 failures crashes, or successful landings off- base?

[nhnifong]

One was a total loss and one I recovered about 160k funds worth of junk from the other.

If I got this right, I need to crash a maximum of 1 in 10 times to keep the spaceplane operational cost lower

http://www.wolframalpha.com/input/?i=223234+-+217534*x+%3D+27395*0.9+

[GoSlash27]

I'm wandering off in the weeds and away from your original question.

For each successful landing, your operational cost is $5,700. For each failure, your operational cost is $223,234. For it's operational cost to match $27,395...

x(223,234)+5,700=27,395

x(223,234)= 21,695

x= .0972

If you make 90.3% of your landings (or at least not crash), you will break even. Yeah, about 1 in 10.

Best,

-Slashy

[Hodo]

I am working on the following two reusable launchers

Overall the rocket has a slightly higher operational cost but It is lower risk. I'd like to calculate the exact landing risk for the plane that makes the operational cost break-even with the rocket.

Both launchers are designed to put a 38.8t payload costing 12k into LKO.

Below, the payload cost is deducted from the operational cost of the launch to make comparing launchers simpler.

Rocket:

Up-front launch cost: 96,547

Perfect recovery revenue: 69,152

Operational cost: 27,395

Spaceplane:

Up-front launch cost: 223,234

Perfect recovery revenue: 217,534

Operational cost: 5,700

And the risks:

Due to limited range control on the recovery of the rocket, (I can't hit KSC on the nose) I can only expect about 90% of the perfect recovery cost.

For the plane What is the probability of crash that will make the operational cost break even with the rocket?

http://i.imgur.com/VbbCtXf.png

http://i.imgur.com/Qpe2kvw.png

I am an avid SSTO spaceplane user. I have built hundreds of them at this point. I have found one big difference between the SSTO spaceplane and the rocket, is startup cost. While rockets are cheaper, they cost more in the long run in KSP. In real life it is almost the opposite.

My current fleet of SSTO spaceplanes come in three load ranges. 1-20 tons, 21-60tons, 61+ tons.

I havent made a new heavy lifter, as I havent needed one yet. But the medium and light SSTOs I have made and they are very cost affective, initial cost on the medium lifter was about 95k, and operational cost was under 3k.

But ultimately it does come down to pilot skill.

[nhnifong]

Slashy I think your answer is correct

Hodo, yeah this is super hard! Slight differences in ascent profile are the difference between making it to orbit with that SSTO and coming up 500 m/s short.

[GoSlash27]

nhnifong,

If it helps, I think you can clean up the design a fair amount and still make your payload requirement. This would reduce your operating cost and also risk.

http://forum.kerbalspaceprogram.com/threads/118728-Slashy-s-1-02-Spaceplane-recipe?p=1922759&viewfull=1#post1922759

This one does 25 tonnes, and as you can see it requires only 6 engines and 6 intakes. I'm sure you could scale that for your needs. 8 engines, 8 intakes, 8 wings, and 33% more rocket fuel will get you 33 tonnes of payload.

Best,

-Slashy

[Hodo]

Slashy I think your answer is correct

Hodo, yeah this is super hard! Slight differences in ascent profile are the difference between making it to orbit with that SSTO and coming up 500 m/s short.

The otherside of this is, who says your SSTO has to be a spaceplane design?

I have seen some quite amazing tail sitter rocket SSTO cargo haulers that are cheap and reliable and require very little actual player skill to recover back at the KSC.

Like I built this ship last year before .24.5 came out.

It wasn't able to take cargo but it wasn't designed to. It was designed to take a small team to Minmus and perform science experiments and return to Kerbin and land at the KSC, which it did.

[Michaelo90]

While rockets are cheaper, they cost more in the long run in KSP. In real life it is almost the opposite.

What real life craft are you comparing to? There are no real life SSTO's, rocket or spaceplane type. If any are ever made, I can almost guarantee that they will be cheaper in the long run than the expendable rockets we use now.

[Hodo]

What real life craft are you comparing to? There are no real life SSTO's, rocket or spaceplane type. If any are ever made, I can almost guarantee that they will be cheaper in the long run than the expendable rockets we use now.

I wasn't comparing it to anything in real life. As far as I know there was a rocket designed that was a SSTO design but never actually used.

[SAI Peregrinus]

What real life craft are you comparing to? There are no real life SSTO's, rocket or spaceplane type. If any are ever made, I can almost guarantee that they will be cheaper in the long run than the expendable rockets we use now.

Unlikely. Expendable rockets don't have to have nearly as strong a structure, and they also don't have to have nearly as much fuel overall. The only really expensive bits of the lower stages are the engines, something like SpaceX's plan to re-use the first stage is likely to be far cheaper than any SSTO for a given payload to orbit. An SSTO has to get its payload + its ENTIRE rocket to orbit, while a staged rocket only has to get the payload and uppermost stage to orbit.

[nhnifong]

nhnifong,

If it helps, I think you can clean up the design a fair amount and still make your payload requirement. This would reduce your operating cost and also risk.

http://forum.kerbalspaceprogram.com/threads/118728-Slashy-s-1-02-Spaceplane-recipe?p=1922759&viewfull=1#post1922759

This one does 25 tonnes, and as you can see it requires only 6 engines and 6 intakes. I'm sure you could scale that for your needs. 8 engines, 8 intakes, 8 wings, and 33% more rocket fuel will get you 33 tonnes of payload.

Best,

-Slashy

Thanks! I think I'll aim smaller. 40t is a lot to ask of a spaceplane

[SkyRender]

The best reusable system is one where you never have to return the reusable parts to Kerbin. This is why ISRU fuel depots are so nice. You can just link up all of your launch stages for the equipment you took up to each other (or repurpose them as fuel ferries between the Mun/Minmus and LKO) and suddenly you have a nice and easy way to store more fuel than you'll probably ever need again. It also lets you launch much lighter SSTOs since they'll be able to refuel in LKO that way.

[Sharpy]

I can honestly recommend the Cygnus family of recoverable SSTO rockets by Warzouz.

It's a series of rockets rated for various payload sizes, capable of bringing given payload to orbit, then deorbiting within "90%" recovery zone of KSP, and in most cases landing in one piece - in the rare cases you fail to save the rocket (some models like to tip over after landing) it's still over 70% parts recovered, in particular the expensive engines and probe cores always survive. Since they drop no stages, if you manage to hit KSP on reentry your only costs are the fuel. If you fail, you can still mostly recover 90% of the funds - thanks to airbrakes and some fuel always leftover for reentry (they require a powered landing assist so don't burn away everything in orbit!) you can fine-tune the landing point pretty well.

And operating them is like 1/8 the hassle of SSTO planes.

I'm currently doing almost all of my launches with them - only trivial tiny stuff like "test X in suborbital flight" is done with SRBs, all the rest goes whole or in parts on top of Cygnus launch stages.

[GoSlash27]

nhnifong,

You may find this useful...

A project I've been working on. It delivers 25t of fuel and oxidizer, uses all low-tech parts (tier 7 or below), operates from level 2 runways, is easy and safe to operate, and costs under $90,000.

Unit cost $87,762

Mission cost with full recovery $8,364

$335 per tonne delivered.

*edit* deducting payload to conform to your figures

Launch cost: $85,467

Recovery cost: $79,470

Mission cost: $5,997

Download link

Best,

-Slashy

Edited July 22, 2015 by GoSlash27

[Foxster]

Maybe a compromise? Fly the craft up to orbit for a low cost but do the final return landing with a bunch of 'chutes? That should de-risk the landing.

[Hotblack Desiato]

What real life craft are you comparing to? There are no real life SSTO's, rocket or spaceplane type. If any are ever made, I can almost guarantee that they will be cheaper in the long run than the expendable rockets we use now.

look at X33 and Venture Star.

nasa designed real SSTO planes, but they had issues with the fuel tanks. those problems are already solved, but the project is stopped...

[X-SR71]

At the risk of being bashed here, why even bother with SSTOs for payloads? I mean, it's a nice academic research, but If you're considering 90% part recovery for your launch stage of your rocket, and you're only not recovering boosters and the fuel spent, then I risk saying it's not worth the trouble trying to make a SSTO to deliver the same payload.

Fuel is not all that expensive, the engine is. I'm happy just to recover that mammoth and the tanks. Strap chutes and there you go!

I do often make SSTOs, but for fun and seldom to deliver payloads in orbit.. They're often refueling and getting somewhere afterwards (mostly Laythe).

[cantab]

If you're lousy at runway landings you can always equip your spaceplanes with parachutes.

[GoSlash27]

At the risk of being bashed here, why even bother with SSTOs for payloads? I mean, it's a nice academic research, but If you're considering 90% part recovery for your launch stage of your rocket, and you're only not recovering boosters and the fuel spent, then I risk saying it's not worth the trouble trying to make a SSTO to deliver the same payload.

Fuel is not all that expensive, the engine is. I'm happy just to recover that mammoth and the tanks. Strap chutes and there you go!

I do often make SSTOs, but for fun and seldom to deliver payloads in orbit.. They're often refueling and getting somewhere afterwards (mostly Laythe).

X-SR71,

You certainly won't get bashed by me.

I use SSTO spaceplanes to deliver stuff but not things. Specifically, whatever needs to be delivered from the KSC to an object in LKO via transfer through a docking port. Whatever is going to be placed in orbit and left there as an assembly rides a conventional booster.

I use SSTO spaceplanes for this job because it's cheaper, safer, and leaves no debris in orbit.

For example, if I want to transfer fuel to a ship being assembled in orbit, at the end of the job I'm left with a fueled ship and an empty can. If I use a spaceplane, the empty can is my plane itself.

Using a spaceplane for putting crew in orbit is also a good deal safer than riding a booster. There are a lot more abort options so I worry less about snapping their little necks (I am very protective of my kerbals).

And *if* you're good at flying planes (which I am) the mission works out much cheaper. This allows me to spend more time doing science and less time completing contracts for funding.

I personally don't build spaceplanes to go any further than LKO. I believe that lugging unnecessary mass to another body and back is a waste of resources. Fun, but wasteful...

tl;dr...

Spaceplanes are a very practical solution when used properly, and I'm a very practical- minded administrator.

Best,

-Slashy

[Gwtheyrn]

I am an avid SSTO spaceplane user. I have built hundreds of them at this point. I have found one big difference between the SSTO spaceplane and the rocket, is startup cost. While rockets are cheaper, they cost more in the long run in KSP. In real life it is almost the opposite.

My current fleet of SSTO spaceplanes come in three load ranges. 1-20 tons, 21-60tons, 61+ tons.

I havent made a new heavy lifter, as I havent needed one yet. But the medium and light SSTOs I have made and they are very cost affective, initial cost on the medium lifter was about 95k, and operational cost was under 3k.

But ultimately it does come down to pilot skill.

In real life, a spaceplane requires considerable maintenance post-mission, which means that engineers and technicians have to be employed at considerable wages. That was the doom of the Space Shuttle program, ultimately. It just got more and more expensive to field. Rockets may be disposable, single-use contraptions, but it's easier, cheaper, and faster to build a new one from new parts than to inspect and repair a used space ship.