Jupiter touch n go
- Thread starter Elon puff
- Start date
4KidsOneCamera
Alliance’s New President // Likes SpaceX replicas
Staff member
Team Valiant
Swingin' on a Star
Atlas
Deja Vu
Fly me to the Moon
Under Pressure
Altaïr
Space Stig, Master of gravity
Staff member
Head Moderator
Team Kolibri
Modder
TEAM HAWK
Atlas
Deja Vu
Under Pressure
Forum Legend
Horus Lupercal
Primarch - Warmaster
Professor
Swingin' on a Star
Deja Vu
Biker Mice from Mars
ET phone home
Floater
Copycat
Registered
No, it's not possible.
Well actually it is, but only if you're intending on making the rocket out of about 12 or more stages.
The trouble is SFSs engines. Specifically their TWR and specific impulse. These mean that in theory terms you're capped at between 5 and 6000 m/s Dv per stage (even with infinite fuel mass) but also because as the mass increases, the number of engines increases as well, there becomes a maximum number of engines you can add before they're essentially only adding weight and not relative thrust.
This problem is increased on Jupiter, where the already low TWR is butchered even more by over 2 and a half times more gravity locally.
For example, I've ran the numbers and it takes exactly the same number of Broadsword engines as it does Frontier engines (5) to achieve a 1.07 TWR for a third of the fuel mass (60t vs 160t). This is only one stage at 3500m/s as well.
With that in mind, I've done the data for the first 4 stages, with just a probe as a payload, the absolute minimum you need.
And it reads like a Rocky Horror Show. (TWR adjusted for Jupiter gravity)
Notice I'm having to use steadily more thrust efficient engines, and less and less Dv per stage?
Wanna see the show for 3500m/s for stage 3 and 4, just to illustrate my point?
That's right folks, adding another 500m/s per stage adds an extra 170 thousand tons to the launch mass.
And we're not even half way to the budget for the most aerodynamically efficient guesstimate.
Then you have to get this monstrosity (which will probably rival a Death Star in mass by this point) to Jupiter from the launch pad. A fun thought considering there's only about a dozen players on any online outlet capable of putting the smallest option 4th stage engine pack (without fuel) into LEO.
Well actually it is, but only if you're intending on making the rocket out of about 12 or more stages.
The trouble is SFSs engines. Specifically their TWR and specific impulse. These mean that in theory terms you're capped at between 5 and 6000 m/s Dv per stage (even with infinite fuel mass) but also because as the mass increases, the number of engines increases as well, there becomes a maximum number of engines you can add before they're essentially only adding weight and not relative thrust.
This problem is increased on Jupiter, where the already low TWR is butchered even more by over 2 and a half times more gravity locally.
For example, I've ran the numbers and it takes exactly the same number of Broadsword engines as it does Frontier engines (5) to achieve a 1.07 TWR for a third of the fuel mass (60t vs 160t). This is only one stage at 3500m/s as well.
With that in mind, I've done the data for the first 4 stages, with just a probe as a payload, the absolute minimum you need.
And it reads like a Rocky Horror Show. (TWR adjusted for Jupiter gravity)
Notice I'm having to use steadily more thrust efficient engines, and less and less Dv per stage?
Wanna see the show for 3500m/s for stage 3 and 4, just to illustrate my point?
That's right folks, adding another 500m/s per stage adds an extra 170 thousand tons to the launch mass.
And we're not even half way to the budget for the most aerodynamically efficient guesstimate.
Then you have to get this monstrosity (which will probably rival a Death Star in mass by this point) to Jupiter from the launch pad. A fun thought considering there's only about a dozen players on any online outlet capable of putting the smallest option 4th stage engine pack (without fuel) into LEO.
Altaïr
Space Stig, Master of gravity
Staff member
Head Moderator
Team Kolibri
Modder
TEAM HAWK
Atlas
Deja Vu
Under Pressure
Forum Legend
Ah, thanks Horus, we know what the ship should look like. However, note that you don't necessarily need a TWR greater than 1 for a fly-by, as you already have a lot of speed. All you have to do could be to maintain that speed by countering drag with thrust... "Could be", because with an atmosphere as thick as on Venus and an orbital speed of 9.2 km/s... Impossible!
Just for fun, I calculated which drag would apply to a ship flying at 9210 m/s (orbital speed from the delta-V map) at "ground" level. I took one of the slickest ship I could design, and the drag it would experience would be... 5.3 GN
Not kilo-Newton, neither Mega-Newton, but actually Giga-Newton! That's more than 1 million Titans.
There's no way you can maintain a sufficient speed in those conditions. Finally we'll have to go with Horus method and to painfully fight gravity and drag... Good luck TtTOtW!
Just for fun, I calculated which drag would apply to a ship flying at 9210 m/s (orbital speed from the delta-V map) at "ground" level. I took one of the slickest ship I could design, and the drag it would experience would be... 5.3 GN
Not kilo-Newton, neither Mega-Newton, but actually Giga-Newton! That's more than 1 million Titans.
There's no way you can maintain a sufficient speed in those conditions. Finally we'll have to go with Horus method and to painfully fight gravity and drag... Good luck TtTOtW!
Horus Lupercal
Primarch - Warmaster
Professor
Swingin' on a Star
Deja Vu
Biker Mice from Mars
ET phone home
Floater
Copycat
Registered
4KidsOneCamera
Alliance’s New President // Likes SpaceX replicas
Staff member
Team Valiant
Swingin' on a Star
Atlas
Deja Vu
Fly me to the Moon
Under Pressure
T
The drag alone going straight up from zero at surface level eats over 6000s Δv. Then, about the same to exit the atmosphere straight up also in beating gravity, and for acceleration. And then, 9223s Δv orbital speed. I... look guys I know this is possible. It's just... you've got to be stupid enough to persist.
Which means is theoretically possible, but, only the drag cause by using all the separators, docking ports, engines... well, anything you use to get 23 000 m/s deltaV... will eventually kill your effort. Also you need to have a TWR of 2.4 on the first, at least, 15 stages... Ughhh... I really think its impossible.
Altaïr
Space Stig, Master of gravity
Staff member
Head Moderator
Team Kolibri
Modder
TEAM HAWK
Atlas
Deja Vu
Under Pressure
Forum Legend
It's not that much, between "surface" and Karman line, I calculated that gravity only dropped by 5.5%. Better than nothing, but that's still a lot...
Good idea. On Earth you fill a balloon with helium, and it will naturally rise, let's do this on Jupiter then. Oh wait, Jupiter's atmosphere is mostly made of hydrogen, and as helium is heavier than hydrogen it will sink too
Jupiter really doesn't want you to escape!
Good idea. On Earth you fill a balloon with helium, and it will naturally rise, let's do this on Jupiter then. Oh wait, Jupiter's atmosphere is mostly made of hydrogen, and as helium is heavier than hydrogen it will sink too
Jupiter really doesn't want you to escape!
Pink
(Mooncrasher)
Staff member
Team Valiant
Discord Staff
Voyager Quest
Man on the Moon
Forum Legend
