Is it possible to create Saturn V(esqe) rocket but with entirely modern/newer technology? What its performance will be like?

[sevenperforce]

On 4/27/2020 at 5:26 PM, Bill Phil said:

This seems off. I may be doing things wrong, but I'm consistently getting around 70 tonnes to TLI.

I used your mass numbers for the Saturn V stages and the same specific impulses and calculated the payload to TLI. It was very close to the known value, within the margin of roundoff error (on the order of kilograms). So my analysis of the Saturn V should check out.

I fixed the issue I was having with stage volumes and dry masses, so now if you plug in everything for the Saturn V exactly as-is, you get the right answer, and the same for other real-life rockets. Can you take another look and let me know if you find any problems?

https://docs.google.com/spreadsheets/d/1UNuPfjZE-YVIrmLINiUMcOzJk-voZ2TqM6R7MgyaM-I/edit?usp=sharing

With the new data, here's what I'm getting:

• Replacing the old Saturn V with the exact same engines but newly-built, lighter stages with common bulkheads should increase TLI payload from 48,600 kg to 56,000 kg.
• Adding new engines increases TLI payload to 84,000 kg. One winning combo appears to be 3 BE-3Us on the third stage, 15 BE-3Us on the second stage, and a whopping 59 Merlin 1Ds on the first stage. You can bump it up to 85 tonnes by swapping out those 59 roaring Merlin 1Ds for 25 RD-191s...what they lack in liftoff thrust and prop densification, they make up for in specific impulse.
• Going methalox-only (Raptor SL and Raptor Vac) easily breaks 100 tonnes to TLI, with the same tank dimensions as the Saturn V. 

And that's without changing tank diameter.

[sevenperforce]

If you go kerolox-methalox-hydrolox with a 10.1-m diameter all the way up, you can hit 118 tonnes to TLI using RD-191s, Raptor Vacs, and BE-3Us.

I still haven't found a good use for the RL-10.

[Bill Phil]

1 hour ago, sevenperforce said:

I fixed the issue I was having with stage volumes and dry masses, so now if you plug in everything for the Saturn V exactly as-is, you get the right answer, and the same for other real-life rockets. Can you take another look and let me know if you find any problems?

https://docs.google.com/spreadsheets/d/1UNuPfjZE-YVIrmLINiUMcOzJk-voZ2TqM6R7MgyaM-I/edit?usp=sharing

Looks pretty good. If it gives you the right values for the Saturn V and other rockets it should be right, or at least close enough.

1 hour ago, sevenperforce said:

With the new data, here's what I'm getting:

• Replacing the old Saturn V with the exact same engines but newly-built, lighter stages with common bulkheads should increase TLI payload from 48,600 kg to 56,000 kg.
• Adding new engines increases TLI payload to 84,000 kg. One winning combo appears to be 3 BE-3Us on the third stage, 15 BE-3Us on the second stage, and a whopping 59 Merlin 1Ds on the first stage. You can bump it up to 85 tonnes by swapping out those 59 roaring Merlin 1Ds for 25 RD-191s...what they lack in liftoff thrust and prop densification, they make up for in specific impulse.
• Going methalox-only (Raptor SL and Raptor Vac) easily breaks 100 tonnes to TLI, with the same tank dimensions as the Saturn V. 

And that's without changing tank diameter.

These look like good numbers to me. Your analysis is more in-depth than mine, I assumed the same tank wet/dry masses. However your analysis takes into account prop density, tank area densities, engine masses, and a lot more. So I think now that you've gone back and fixed those earlier issues the numbers should be good. Really we'd need to use OTIS or STK to get a proper answer (or some Python scripts... but that might get ugly). There might be a few more issues but I suspect they're minor ones.

Man, nearly 8 extra tonnes to TLI just from modern construction alone. That's pretty good on its own.

But 84 tonnes to TLI with new engines? Now that's just insane. Still, that's pretty awesome. Imagine what we could do with a launcher like that?

100 tonnes to TLI is even more insane! But it is possible. Imagine the kind of exploration we could do? 

And if we change the upper stage diameter to 10.1 meters...

Considering Trans Mars Injection only takes around 500 m/s more than escape velocity, and TLI is already quite close to escape velocity, we could probably get 100 tonnes to escape velocity. Now I'm wondering about 12 meter rockets for direct Mars insertion...

1 hour ago, sevenperforce said:

If you go kerolox-methalox-hydrolox with a 10.1-m diameter all the way up, you can hit 118 tonnes to TLI using RD-191s, Raptor Vacs, and BE-3Us.

I still haven't found a good use for the RL-10.

Yeah some engineers at MSFC have told me about the huge losses from using the RL-10. Since the RL-10 has low thrust. The EUS apparently has worse losses than the ICPS but it makes up for it with size. And the reason they can't use higher thrust is because someone decided to deploy the Orion's solar panels before TLI...

But maybe it'd be useful for high C3 but modest payload trajectories like a Neptune orbiter.

Just goes to show that engines optimized for a few tonnes to GTO are not good options TLI stages if you want large payloads.

Edited April 29, 2020 by Bill Phil

[sevenperforce]

11 hours ago, Bill Phil said:

Looks pretty good. If it gives you the right values for the Saturn V and other rockets it should be right, or at least close enough.

Flying without any solid boosters, the Atlas V can reach a 28.7-degree LEO with 8210 kg of payload using its large, 5.4-meter PLF and with 9800 kg using its smaller, 5-meter PLF. My model gives it 9957 kg to LEO with the 5.4-meter PLF and 10,030 kg to LEO with the 4-meter fairing, but warns that second-stage T/W is dangerously low, which would require a lofted trajectory and higher gravity drag on both stages. My model adjusts for T/W ratio, but only in terms of how burn time impacts average gravity drag; if a trajectory is significantly different than the Saturn V's then the total gravity drag will be underquoted.

So getting relatively close to the actual Atlas V performance using a model designed around the Saturn V ascent profile is encouraging. If I can, I'll add the option to tack on SRBs and see if I can get it to accurately match Atlas V 551 as well as SLS.

I went in and added a dV calculator to the spreadsheet so it displays wanting or excess dV from TLI at the very top, hopefully enabling you to compare to various earth escape missions if you know the dV past LEO. If you check the reference sheet you'll see that the free-return TLI used by the Apollo missions required 3,039 m/s past LEO. Required dV from LEO to Mars intercept is 3.6-4.3 km/s, so based on my model the Saturn V could have sent 31.5-40 tonnes direct to Mars. I know that Von Braun's analysis of the Saturn V gave it 45 tonnes to C3 so that's probably in the ballpark.

[sevenperforce]

16 hours ago, Bill Phil said:

But 84 tonnes to TLI with new engines? Now that's just insane. Still, that's pretty awesome. Imagine what we could do with a launcher like that?

Someone else (might have been you) playing around on the spreadsheet found that by stretching the first stage tanks to 40 meters and and the second to 25, using nothing but Raptors, you can launch 91.5 tonnes to TLI...

...using 1960s construction techniques and mass fractions.

Edited April 29, 2020 by sevenperforce

[RCgothic]

Played around a bit and added a few notes for additional DV to get to other planets.

I'm not sure the payload fairing or LES mass get incorporated anywhere? Doesn't seem to change any of the DV or TWR figures.

Edited April 29, 2020 by RCgothic

[sevenperforce]

52 minutes ago, RCgothic said:

Played around a bit and added a few notes for additional DV to get to other planets.

I'm not sure the payload fairing or LES mass get incorporated anywhere? Doesn't seem to change any of the DV or TWR figures.

Is that dV the dV beyond TLI or the dV from LEO? or from C3=0?

The PLF and LES are just negligible compared to the really large payloads and rockets we're talking about. They are added to the dry mass of the first stage. It is assumed that they are dropped at or around the first stage burnout.

[RCgothic]

Well I made a LES weighing 500,000t and the first stage still gets off the ground.

You seem to be playing with it now. Not sure if you fixed it or it was just extreme lag finally working itself loose...

Edited April 29, 2020 by RCgothic

[Bill Phil]

@sevenperforce

I think adding a total height calculation would be useful, and compare it to the height of the VAB doors. If it's too tall it can't make it out of the VAB, but even if the stack itself is short enough you may not have much excess room for different payload heights.

1 hour ago, RCgothic said:

I'm not sure the payload fairing or LES mass get incorporated anywhere? Doesn't seem to change any of the DV or TWR figures.

 

19 minutes ago, sevenperforce said:

Is that dV the dV beyond TLI or the dV from LEO? or from C3=0?

The PLF and LES are just negligible compared to the really large payloads and rockets we're talking about. They are added to the dry mass of the first stage. It is assumed that they are dropped at or around the first stage burnout.

I checked the F17 cell on the first page and it didn't include the LES mass in the dry mass of the first stage - I added it though. If it was included in some other way it's an easy fix.

2 minutes ago, RCgothic said:

Well I made a LES weighing 500,000t and the first stage still gets off the ground.

You seem to be playing with it now. Not sure if you fixed it or it was just extreme lag finally working itself loose...

I think that was me - I added the LES mass to the dry mass for Stage 1 and the excess delta-V for the 500,000t LES went down to -3000 something.

[RCgothic]

1 minute ago, Bill Phil said:

@sevenperforce

I think adding a total height calculation would be useful, and compare it to the height of the VAB doors. If it's too tall it can't make it out of the VAB, but even if the stack itself is short enough you may not have much excess room for different payload heights.

 

I checked the F17 cell on the first page and it didn't include the LES mass in the dry mass of the first stage - I added it though. If it was included in some other way it's an easy fix.

I think that was me - I added the LES mass to the dry mass for Stage 1 and the excess delta-V for the 500,000t LES went down to -3000 something.

Ah yes, that's what I saw.

[sevenperforce]

38 minutes ago, RCgothic said:

Well I made a LES weighing 500,000t and the first stage still gets off the ground.

You seem to be playing with it now. Not sure if you fixed it or it was just extreme lag finally working itself loose...

Ah, thanks. I went into my code and it looks like I used to have a cell that summed the PLF mass and the LES mass but I ended up moving it and Google Sheets failed to change the pointer. Just fixed it in all sheets.

Note -- even though the "Build: 3 Stages to the moon" tabs appear locked, they are not; you can still edit the greyed parts.

What was the excess dV for? Is that excess past TLI?

38 minutes ago, Bill Phil said:

I think adding a total height calculation would be useful, and compare it to the height of the VAB doors. If it's too tall it can't make it out of the VAB, but even if the stack itself is short enough you may not have much excess room for different payload heights.

Which VAB?

[Bill Phil]

8 minutes ago, sevenperforce said:

Which VAB?

I was thinking the Kennedy Space Center VAB. 

Could be any, but that seems to be the easiest to find, plus that's the one the Saturn V rolled out from. Though you would probably also need to consider the MLP height.

[RCgothic]

10 minutes ago, sevenperforce said:

Ah, thanks. I went into my code and it looks like I used to have a cell that summed the PLF mass and the LES mass but I ended up moving it and Google Sheets failed to change the pointer. Just fixed it in all sheets.

Note -- even though the "Build: 3 Stages to the moon" tabs appear locked, they are not; you can still edit the greyed parts.

What was the excess dV for? Is that excess past TLI?

Which VAB?

I tried to edit and got an error message, which is why I created a sandbox. The DVs listed are excess past TLI.

[sevenperforce]

3 minutes ago, RCgothic said:

I tried to edit and got an error message, which is why I created a sandbox. The DVs listed are excess past TLI.

I set it up so you can only edit the greyed cells. But the sandbox is fine too.

4 minutes ago, Bill Phil said:

I was thinking the Kennedy Space Center VAB. 

Could be any, but that seems to be the easiest to find, plus that's the one the Saturn V rolled out from. Though you would probably also need to consider the MLP height.

Hmm, I wonder where I could find that info.

Here we go. 456 feet or 139 meters. I wonder how tall the MLP was.

 

[Hannu2]

On 4/29/2020 at 12:57 AM, JoeSchmuckatelli said:

Do we even really need a similar size? 

 

Haven't we been using Delta 2s for Mars probes?  

 

Need is not driving force in space. To be honest, we do not need anything but telecommunication and some surveillance satellites on LEO (to live normal live and run normal business). All manned operations and astronomic research are "nice to have" things, which get small public funding from wealthy countries. I think that in USA space research funding is less than a percent in federal budget and in all other countries much less or nothing. Economic or environmental benefits of other celestial bodies (for example asteroid mining) are behind huge economic and developing processes and any state government or large capital owners do not see reasonable profit possibilities in reasonable time scale in such operations.

Musk may have some ideology, behind his business but he is also clever and greedy businessman. I think all that manned Mars hype is a vision but not important reason behind his investments. Global satellite network is. It may pay all investments in SpaceX back and give very good profit in his lifetime, if everything goes well. Manned Mars operations will take decades, probably couple of generations and need economic resources and political will of superpower state. Even richest individuals can not fund such an effort, even they can operate about an order of magnitude lower costs than public space administrations.

There is no real need of superrockets. No funded plans base on them, for obvious reasons, because there are no such rockets and development schedules are known to be extremely overoptimistic and unrealistic. And it is difficult to get funds for superrockets, because no-one can say clear use for them. But I am sure that if such rockets will be available, for example BFR or New Glenn, satellite industry will soon learn to get benefits from their increased capacity. Also public projects will benefit if mass limits are significantly higher and cost per kg lower.

It is the same thing in all transport logistics. Bigger units are always economically better. The whole development of ships, airplanes, trains and trucks have been increasing sizes and loads. Every generation have been bigger than predecessors and cost of transport (per ton and kilometer) have fall down even unit cost of behemoth class devices have increased. It is also economically possible to obey more strict safety regulations and environmental protection measures in single massive and expensive unit than distribute them to many smaller units. I do not see any reason to expect that space transport will differ from general rule.

 

[RCgothic]

The key thing about SSSH is that it aims to cost roughly a tenth of falcon 9 per flight.

Being a super-rocket makes that easier, but isn't really directly relevant.

SSSH could be twice as large and lift half as much as the current design and as long as it comes within an order of magnitude of its cost goal it would still make every other booster with a payload smaller than SLS Block 1B cargo completely obsolete.

[sevenperforce]

4 hours ago, RCgothic said:

The key thing about SSSH is that it aims to cost roughly a tenth of falcon 9 per flight.

Being a super-rocket makes that easier, but isn't really directly relevant.

SSSH could be twice as large and lift half as much as the current design and as long as it comes within an order of magnitude of its cost goal it would still make every other booster with a payload smaller than SLS Block 1B cargo completely obsolete.

I will probably add a checkout cell with something like "ALERT: Too large to fit in VAB" and "WARNING: Rockets over 160 m are unlikely to yield accurate data with this ascent profile and characteristics."

I would like to find a mathematical relationship for structural density. There is a point where it should start to scale up.

[JoeSchmuckatelli]

6 hours ago, Hannu2 said:

Need is not driving force in space. To be honest, we do not need anything but telecommunication and some surveillance satellites on LEO (to live normal live and run normal business). All manned operations and astronomic research are "nice to have" things, which get small public funding from wealthy countries. I think that in USA space research funding is less than a percent in federal budget and in all other countries much less or nothing. Economic or environmental benefits of other celestial bodies (for example asteroid mining) are behind huge economic and developing processes and any state government or large capital owners do not see reasonable profit possibilities in reasonable time scale in such operations.

Musk may have some ideology, behind his business but he is also clever and greedy businessman. I think all that manned Mars hype is a vision but not important reason behind his investments. Global satellite network is. It may pay all investments in SpaceX back and give very good profit in his lifetime, if everything goes well. Manned Mars operations will take decades, probably couple of generations and need economic resources and political will of superpower state. Even richest individuals can not fund such an effort, even they can operate about an order of magnitude lower costs than public space administrations.

There is no real need of superrockets. No funded plans base on them, for obvious reasons, because there are no such rockets and development schedules are known to be extremely overoptimistic and unrealistic. And it is difficult to get funds for superrockets, because no-one can say clear use for them. But I am sure that if such rockets will be available, for example BFR or New Glenn, satellite industry will soon learn to get benefits from their increased capacity. Also public projects will benefit if mass limits are significantly higher and cost per kg lower.

It is the same thing in all transport logistics. Bigger units are always economically better. The whole development of ships, airplanes, trains and trucks have been increasing sizes and loads. Every generation have been bigger than predecessors and cost of transport (per ton and kilometer) have fall down even unit cost of behemoth class devices have increased. It is also economically possible to obey more strict safety regulations and environmental protection measures in single massive and expensive unit than distribute them to many smaller units. I do not see any reason to expect that space transport will differ from general rule.

 

 

5 hours ago, RCgothic said:

The key thing about SSSH is that it aims to cost roughly a tenth of falcon 9 per flight.

Being a super-rocket makes that easier, but isn't really directly relevant.

SSSH could be twice as large and lift half as much as the current design and as long as it comes within an order of magnitude of its cost goal it would still make every other booster with a payload smaller than SLS Block 1B cargo completely obsolete.

Thanks for the response!  Never even occurred to me to think in economic terms... Despite having read time and time again about how expensive it is to use RU launch sites for our astronauts and how expensive it is to lift stuff up there in general... And to think; I literally just read a scathing critique of the Shuttle program based on the inefficient and economically unsustainable nature of the continued use of the early designs in a program that initially called for a sort of tick-tock implementation-utilization-improvement cycle. 

 

Guessing I'm conditioned to think about space as just 'government expenditures' - and you guys have exposed to me my own hidden bias. 

 

Smh - efficiency matters just as much as capacity! 

 

Grin

Edited April 30, 2020 by JoeSchmuckatelli

[Exoscientist]

On 4/24/2020 at 10:34 PM, Reactordrone said:

RD-170s have similar thrust to an F-1 so you could do a first stage without external boosters and carry 100 tonnes less propellant for the same delta-v. That would also reduce gravity drag since your TWR would be higher (and the Saturn V had terrible TWR on the pad).

 I speculated on a HLV using the Russian RD-171 engines here:

https://exoscientist.blogspot.com/2012/05/low-cost-hlv.html

 

  Bob Clark

[mikegarrison]

23 hours ago, Hannu2 said:

It is the same thing in all transport logistics. Bigger units are always economically better. The whole development of ships, airplanes, trains and trucks have been increasing sizes and loads.

This is oversimplified.

In airplanes, for instance, why are single-aisle airplanes like the 737 and A320 so popular, when larger airplanes may have better fuel/seatmile? The answer is because the biggest areas of growth for air travel have been in point-to-point service rather than travel between hubs. Operators have been able to make more money by flying more frequent schedules (so thus, more convenient times) directly between smaller markets (so thus, more convenient routing) than by using the hub/spoke model that gathered all the passengers into fewer, larger flights.

Why are package delivery services investigating things like 1-2 package drone delivery instead of throwing everything onto a big truck?

Bigger is certainly not always better. It takes more fuel to drive around a bus than it does a regular-sized car, which is why taxis are not generally 30-passenger buses. But if you do want to take 30 passengers somewhere, a bus is more efficient than a fleet of cars, which is why charter bus companies also exist.