Reusable rocket challenge

[SynX]

Landing of boosters is a very useful skill in career mode and in real life. My idea is to make a booster capable of sending some  payload to LKO as a SSTO, and then land as close to the space center as possible. The launch cost (total cost - payload cost after mission completed)  is calculated, and will generate a scoreboard based on cost per ton. Tundra exploration and dependencies are allowed, but no MJ and no cheats like infinite propellant.

 

Edited November 1, 2020 by SynX

[king of nowhere]

i doubt 50 is possible. you still need to spend money on fuel. what you ask would require sending one ton to orbit with 200 kg of fuel

ok, it would be technically possible if you start with empty tanks, fill them with isru on the launchpad, and then you launch the rocket. but it kinda defies the purpose of it

Edited October 31, 2020 by king of nowhere

[Pds314]

50 funds per tonne of payload is very difficult. As a simple LFO booster it's definitely impossible, seeing as even with very favorable assumptions it should have less than half the delta-V for orbit. You're asking us to make an SSTO booster with a 60% payload fraction. Not possible.

It might technically be possible for some kind of very optimized RAPIER + Nerv SSTO, or of course magic wing prop + Nerv SSTO, but do keep in mind Nerv fuel is expensive and nerve and rapiers are heavy.

 

Re: Rapier-Nerv SSTOs: this thing by Bradley Whistancd probably qualifies. It has 363 tonnes of fuel for a 1000 tonne payload.

 

Edited October 31, 2020 by Pds314

[ralanboyle]

@SynX May I suggest, rather than setting a limit to the funds spent; this could have a leaderboard based on being the most efficient cost per ton placed in orbit while requiring all stages land within a certain distance from KSC. Also, If you are focused on booster landing then you might add "no wheels." 

[vyznev]

10 hours ago, Pds314 said:

It might technically be possible for some kind of very optimized RAPIER + Nerv SSTO, or of course magic wing prop + Nerv SSTO, but do keep in mind Nerv fuel is expensive and nerve and rapiers are heavy.

Hmm, if we're going to exploit physics bugs, surely a Zompi drive or some other form of reactionless kraken drive would be more useful here than magic wing props?  But I guess that would kind of trivialize the challenge.

1 hour ago, ralanboyle said:

Also, If you are focused on booster landing then you might add "no wheels."

Mind you, "no wheels" doesn't necessarily mean "no horizontal landing."  Although it does make it quite a bit more challenging, especially if the goal is not to lose parts.

[SynX]

Nice suggestions... will change it to a scoreboard based on cost per payload.

Edited November 1, 2020 by SynX

[ralanboyle]

Okay, I made a few assumptions and took a stab at the spirit of this challenge. I made a traditional VTOL rocket, which carries a payload on top. It achieves orbit without staging and delivers it's payload in LKO. Then it returns to KSC and lands propulsivly.  There are much more efficient ways to get payloads to orbit but I think this is what @SynX intended.  I've included the fueled/unfueled and views w/wo payload at the end of the video but here is the math. 

Weight

WO Payload -105825

With Payload -179475

Payload Weight - 73650

Cost

Fueled - 306690

Unfueled - 259688

Cost of Fuel - 47002

Fuel is the only cost of flight (beside payload). 

So the fractional cost: 1.6kg/$ or $638/T to LKO

 

 

Edited November 3, 2020 by ralanboyle

[SynX]

On 11/1/2020 at 9:25 AM, ralanboyle said:

@SynX May I suggest, rather than setting a limit to the funds spent; this could have a leaderboard based on being the most efficient cost per ton placed in orbit while requiring all stages land within a certain distance from KSC. Also, If you are focused on booster landing then you might add "no wheels." 

Good idea... “no wheels” might be unnecessary tho, I don’t care about how the spacecraft works, I just care about reliability and cost per kilo per launched...

i did a Tundra exploration rocket, utilising a 5m Superheavy booster that costs about 510000 funds, can carry about 100 tons to a 90km orbit with 300m/s left. After decoupling, the booster on its own will have some 630m/s. It carries 56000 units of fuel and oxidizer, costs about 40000 funds and that is the only cost... To land the booster, I deorbit the booster 120 degrees away from the KSC, and in a way it will slightly overshoot(as indicated by Trajectories), then use airbrakes to tune the landing spot... at 3000m, I slow down to some 280m/S with airbrakes. Notice RCS uses fuel too... Quick save, then I might use parachutes to keep the thing up straight and save fuel... of course they’re insufficient to slow down the whole booster, then I fire the engines to slow further down...  if parachutes are not used, the propulsive landing will take 400m/s. Since it’s fired at the last moment, usually need several tries to get a successful landing.

the parachute assisted landing will take about 200m/s from orbit to ground, and the propulsive landing only will take about 500m/s.

Edited November 12, 2020 by SynX

[moar ssto]

On 10/31/2020 at 9:46 PM, Pds314 said:

50 funds per tonne of payload is very difficult. As a simple LFO booster it's definitely impossible, seeing as even with very favorable assumptions it should have less than half the delta-V for orbit. You're asking us to make an SSTO booster with a 60% payload fraction. Not possible.

It might technically be possible for some kind of very optimized RAPIER + Nerv SSTO, or of course magic wing prop + Nerv SSTO, but do keep in mind Nerv fuel is expensive and nerve and rapiers are heavy.

 

Re: Rapier-Nerv SSTOs: this thing by Bradley Whistancd probably qualifies. It has 363 tonnes of fuel for a 1000 tonne payload.

 

crafts involving magic wings will have less payload fraction and inorbit live/dead mass ratio compared to conventional wings rapier nerv sstos, this will be just worse if you use magic props. since the whole craft will be essesntially a set of giant propellers+wings. The big value of magic wings is that they allow your carft to pack much higher usable atmospheric dv, than conventional wing sstos, but not with good mass efficiency.

There might be a chance of getting high payload fraction on magic wing is by using extremely small wing area and a very long runway, such as the polar icecaps,  but definitely no carft from ksc runway or grass can be more efficient than the 70%payload of rapier nerv sstos.

Sorry, I didn't realise that this is about cost efficiecy and not mass efficiency, you are right then.

Edited November 12, 2020 by moar ssto