3 ms·

Now I would like to see them attach 7 boosters together in a hexagonal pattern and get them all to land safely.

LeifCarrotson 9y ago
The Falcon Heavy is basically attaching 3 boosters together in a line. Unfortunately for your vision, the Falcon Heavy boosters separate and land one-by-one as individual boosters. Your idea does make some intuitive sense. While lifting the single booster and even with just one of 9 engines turned down to minimum throttle, when the payload is gone and the tanks are near empty there's an enormous excess of power. The minimum thrust-to-weight ratio is still like 2:1. This means you have to run a "hoverslam" profile which reaches zero velocity precisely at the deck, otherwise you'll take off again. And it means you come in terrifyingly hot and fast, resulting in the explosions in the linked video. With 7 boosters strapped together, you'd think there could be a more appropriate ratio of power and mass, which would enable a more controlled, sedate, hover-and-land profile. If the current 40% throttled down single-engine, single-booster TWR is 2:1, 3 engines would give you a 0.86:1 to 2.14:1 TWR. They could even turn on 3 engines at the outer corners in an equilateral triangle, and use both gimballing and differential thrust to control your descent. It should be easy. You'd just get some struts and select hexagonal symmetry...oh wait, no, that's KSP. In reality, landing 7 boosters at once with a near-unity TWR would be much more expensive in terms of fuel. You want a hoverslam profile that's almost too fast to control, because then you can get your payload higher and faster. Right now, with the single 9-engine booster, they sometimes burn 3 of the 9 engines to land (giving a >6:1 power-to-weight ratio). They do this when they're short on fuel because for every second that they are airborne, they're suffering a 9.8 m/s hit to their delta-V. They want to come down as fast as possible to minimize time in the air.
- jlebrech 9y ago
  my plan would be to separate the boosters too, you just need them stuck together at launch. or another plan would be to keep them together all the way to mars, and you have a habitation unit above the boosters which is their combined surface area. when you launch the habitation unit you can later land another one next to it the to tile them together.

The Falcon Heavy is basically attaching 3 boosters together in a line. Unfortunately for your vision, the Falcon Heavy boosters separate and land one-by-one as individual boosters. Your idea does make some intuitive sense. While lifting the single booster and even with just one of 9 engines turned down to minimum throttle, when the payload is gone and the tanks are near empty there's an enormous excess of power. The minimum thrust-to-weight ratio is still like 2:1. This means you have to run a "hoverslam" profile which reaches zero velocity precisely at the deck, otherwise you'll take off again. And it means you come in terrifyingly hot and fast, resulting in the explosions in the linked video. With 7 boosters strapped together, you'd think there could be a more appropriate ratio of power and mass, which would enable a more controlled, sedate, hover-and-land profile. If the current 40% throttled down single-engine, single-booster TWR is 2:1, 3 engines would give you a 0.86:1 to 2.14:1 TWR. They could even turn on 3 engines at the outer corners in an equilateral triangle, and use both gimballing and differential thrust to control your descent. It should be easy. You'd just get some struts and select hexagonal symmetry...oh wait, no, that's KSP. In reality, landing 7 boosters at once with a near-unity TWR would be much more expensive in terms of fuel. You want a hoverslam profile that's almost too fast to control, because then you can get your payload higher and faster. Right now, with the single 9-engine booster, they sometimes burn 3 of the 9 engines to land (giving a >6:1 power-to-weight ratio). They do this when they're short on fuel because for every second that they are airborne, they're suffering a 9.8 m/s hit to their delta-V. They want to come down as fast as possible to minimize time in the air.

jlebrech 9y ago
my plan would be to separate the boosters too, you just need them stuck together at launch. or another plan would be to keep them together all the way to mars, and you have a habitation unit above the boosters which is their combined surface area. when you launch the habitation unit you can later land another one next to it the to tile them together.