Moon SSTO

[phantom]

Normal: Make an SSTO that can enter a stable Moon orbit.
Hard: Make an SSTO that can land on the Moon
Extreme: Make an SSTO that can go to the Moon, land on it, and return

 

[Pink]

Show us.

 

[JSP]

Normal: Make an SSTO that can enter a stable Moon orbit.
Hard: Make an SSTO that can land on the Moon
Extreme: Make an SSTO that can go to the Moon, land on it, and return

I'll do it if you show us your attempt thats how it works you show your attempt first then we'll do it

 

[Horus Lupercal]

I've some entries for you.

https://jmnet.one/sfs/forum/index.php?threads/single-stage-to-moon.2259/

That's hard and extreme sorted.

Infact, I'm sure someone managed it with 3 parts

Edit. Yeah, john did a return lunar trip with powered landings each side with 3 parts.

 

[Cosmo's fan]

Okay my first try on a ssto

Still working on it

 

[phantom]

Attempt 1 just crashed into the moon

 

[phantom]

I put it in an orbit:

 

[phantom]

I put it in an orbit: View attachment 37773 View attachment 37772

I don't think that I have enough deltaV for a moon landing

 

[JSP]

Ok I'm going to have a try now

 

[phantom]

Well the landing didn't go well

 

[phantom]

View attachment 37774 Well the landing didn't go well

One RCS block survived the crash, I'll count that as a win

 

[Pink]

One RCS block survived the crash, I'll count that as a win

Sorry mate, it has to be controllable

 

[Gurren Lagann]

I'm waiting on a challenge from you that is actually challenging for most of us.

 

[Bananas]

One RCS block survived the crash, I'll count that as a win

Since when did we count that as a "win". We have a much higher standard then where ever you're coming from.

 

[Altaïr]

One RCS block survived the crash, I'll count that as a win

Ok, now I'm waiting to see the return to Earth
No seriously, when we say "landing" it means "landing in one piece", without breaking anything. Crashing is not landing.

 

[Horus Lupercal]

I've some entries for you.

https://jmnet.one/sfs/forum/index.php?threads/single-stage-to-moon.2259/

That's hard and extreme sorted.

Infact, I'm sure someone managed it with 3 parts

Edit. Yeah, john did a return lunar trip with powered landings each side with 3 parts.

You know what kids, I think I've got it all wrong.

Normal is easy and anyone should be achieving that.
Hard without breaking anything is actually pretty tasty.
Extreme, I don't think is actually legally do-able without ions.

I've spent most of the night attempting the most cheesy efficient, no holds barred maximum Dv capable but realistic SSTO design.

And I'm short a return trip by quite a margin.

Most of the SSTOs in the post I referenced claim a return for under 4,000m/s. Johns generates just short of 4600m/s.
The one I've built produces between 4844 and 4906m/s (this is with a probe, landing gear, parachutes and aero surfaces at 6.35t total), and I'm out of fuel 2/3rds of the way back into lunar orbit after landing.

I even got into the weeds of where I'm spending it (numbers taken from whole fuel percentages and may be slightly off actual).
LEO 3334.95 m/s
TLI 703.50 m/s
Landing 551.43m/s
Total = 4589.88m/s
That leaves me with 255.06m/s to lift from the moon and encounter Earth for some aerobrake and parachute action.


The problem is several fold.
The biggest budget burner is the lift to LEO. Cos of drag and a low ish TWR, the Dv score is about 4-500m/s higher than the 'industry standard' (which needs revising in my opinion). I could maybe get the launch down to 3200m/s as that's the lowest I've seen properly work.
TLI is almost bang on the map prediction and considering I'm going off whole percentages, I'm willing to take that as a graphical inaccuracy.
The landing isn't from LLO. That's from the direct injection, suicide burning in from 30km Earth apoapsis to 2000m lunar periapse like a madman. I could probably knock 50-100m/s off that. Which is about 1/2 of a percent of the fuel onboard.
.
Next comes the TWR and Dv problem. 4900m/s is on the limits of what an SSTO in game can generate and cos Tsiolkovsky is a harsh tyrant, adding more fuel isn't saving me as I'm well into the realm of diminishing returns.
For example, 4,000m/s can be achieved with 3 engines and less than 100t of rocket.
4850m/s needs 17 engines and 660t of rocket.
4950t (depending on engine combo) can be 1200-1700tons.
The theoretical maximum with infinite fuel mass is 6347m/s, with just engine and fuel.
You can see where I'm going here.

And then comes TWR. 4850m/s at 660t requires using the best stage engine in game, Broadsword. Lots and lots of broadswords.
But the engine base TWR isn't amazing, and there comes again a point where adding more engines to increase TWR just instead adds fuel mass to power the new engines without actually increasing relative TWR.
Worse is the more engines you add beyond a certain point, the TWR actually drops as the fuel required to feed it outweighs its additional thrust. This is especially the case when you bump in a hawk or titan for a bit of that extra base TWR they have, but the low efficiency means extra fuel which nullifies the TWR increase.

 

[phantom]

The SSTO can have a lander attached as long as it gets into orbit in one stage

 

[phantom]

You know what kids, I think I've got it all wrong.

Normal is easy and anyone should be achieving that.
Hard without breaking anything is actually pretty tasty.
Extreme, I don't think is actually legally do-able without ions.

I've spent most of the night attempting the most cheesy efficient, no holds barred maximum Dv capable but realistic SSTO design.

And I'm short a return trip by quite a margin.

Most of the SSTOs in the post I referenced claim a return for under 4,000m/s. Johns generates just short of 4600m/s.
The one I've built produces between 4844 and 4906m/s (this is with a probe, landing gear, parachutes and aero surfaces at 6.35t total), and I'm out of fuel 2/3rds of the way back into lunar orbit after landing.

I even got into the weeds of where I'm spending it (numbers taken from whole fuel percentages and may be slightly off actual).
LEO 3334.95 m/s
TLI 703.50 m/s
Landing 551.43m/s
Total = 4589.88m/s
That leaves me with 255.06m/s to lift from the moon and encounter Earth for some aerobrake and parachute action.


The problem is several fold.
The biggest budget burner is the lift to LEO. Cos of drag and a low ish TWR, the Dv score is about 4-500m/s higher than the 'industry standard' (which needs revising in my opinion). I could maybe get the launch down to 3200m/s as that's the lowest I've seen properly work.
TLI is almost bang on the map prediction and considering I'm going off whole percentages, I'm willing to take that as a graphical inaccuracy.
The landing isn't from LLO. That's from the direct injection, suicide burning in from 30km Earth apoapsis to 2000m lunar periapse like a madman. I could probably knock 50-100m/s off that. Which is about 1/2 of a percent of the fuel onboard.
.
Next comes the TWR and Dv problem. 4900m/s is on the limits of what an SSTO in game can generate and cos Tsiolkovsky is a harsh tyrant, adding more fuel isn't saving me as I'm well into the realm of diminishing returns.
For example, 4,000m/s can be achieved with 3 engines and less than 100t of rocket.
4850m/s needs 17 engines and 660t of rocket.
4950t (depending on engine combo) can be 1200-1700tons.
The theoretical maximum with infinite fuel mass is 6347m/s, with just engine and fuel.
You can see where I'm going here.

And then comes TWR. 4850m/s at 660t requires using the best stage engine in game, Broadsword. Lots and lots of broadswords.
But the engine base TWR isn't amazing, and there comes again a point where adding more engines to increase TWR just instead adds fuel mass to power the new engines without actually increasing relative TWR.
Worse is the more engines you add beyond a certain point, the TWR actually drops as the fuel required to feed it outweighs its additional thrust. This is especially the case when you bump in a hawk or titan for a bit of that extra base TWR they have, but the low efficiency means extra fuel which nullifies the TWR increase.

If only the game had rapier engines and wings

 

[4KidsOneCamera]

If only the game had rapier engines and wings

They would be a cool addition, but it is already super easy to make an SSTO without them. I could see wings having many other implications though.

 

[Altaïr]

The SSTO can have a lander attached as long as it gets into orbit in one stage

That's quite unexpected, "SS" means "Single stage", if you add a lander it's not a SSTx anymore.
By the way, changing the rules of the challenge might not be very appreciated after that several people gave it a try by following the initial rules... To avoid that, it's a good practice to try your own challenge before posting it. This will give you an idea about how realistic your idea is.

 

[Pink]

The SSTO can have a lander attached as long as it gets into orbit in one stage

What, like this?

LMAO

 

[Horus Lupercal]

If only the game was more like kerbal space program.

I'm not quite sure how wings will help in a 2D game except add dry mass.

The SSTO can have a lander attached as long as it gets into orbit in one stage

That's quite unexpected, "SS" means "Single stage", if you add a lander it's not a SSTx anymore

I think he means an SSTO, with a lander as a payload. Rather than 2 stage rocket.
So the SSTO gets the lander to LLO, the lander lands, then launches and RVs with the SSTO and then they return back to Earth.

 

[Altaïr]

I think he means an SSTO, with a lander as a payload. Rather than 2 stage rocket.
So the SSTO gets the lander to LLO, the lander lands, then launches and RVs with the SSTO and then they return back to Earth.

Ah, you're right. I was reasoning as "single stage for the whole mission" (since "SSTO" is not supposed to mean a Moon mission anyway...)
But this kills completely the challenge, even the hard mode is very easy now

 

[Horus Lupercal]

Ah, you're right. I was reasoning as "single stage for the whole mission" (since "SSTO" is not supposed to mean a Moon mission anyway...)
But this kills completely the challenge, even the hard mode is very easy now

Dunno, it could make it even harder as the SSTLO still needs to get to moon orbit and back, but with a bigger payload.

 

[Gurren Lagann]

Dunno, it could make it even harder as the SSTLO still needs to get to moon orbit and back, but with a bigger payload.

I had once made a one-way SSTP (Single Stage to Pluto), maybe i can try the so-called "Kaizo" difficulty.