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Questions tagged [vertical-landing]

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What is the advantage of the "Mechazilla arms" over fitting the Super Heavy booster with landing struts?

SpaceX lands the Falcon 9 booster stages on its built-in landing struts, this works well. However, the plan to land the Super Heavy booster stage is to capture it in a set of mechanical arms dubbed &...
Frank van Wensveen's user avatar
-4 votes
2 answers
362 views

Why SpaceX decided to forgo the opportunity of a mock soft-landing (on water) for Super Heavy?

The first test flight would be a great chance to test vertical landing controls in the 'first stage' and maybe save some engines for after the flight examination. Source: CNN "Less than three ...
TheMatrix Equation-balance's user avatar
1 vote
1 answer
938 views

What guidance algorithm does Falcon 9 use during powered descent and landing?

The SpaceX Falcon 9 does a powered touchdown with a rocket thrust higher than mass, so is not able to establish a low altitude hover and final descent as used by the Apollo lander. Instead it needs to ...
GremlinWranger's user avatar
1 vote
1 answer
218 views

SpaceX Dragon: why no powered landing? [duplicate]

Can someone explain why SpaceX ditched their plans for powered landing on Dragon spacecraft? Was it fuel constraints? Or maybe the burden of testing and certifying the landing system for NASA? More ...
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1 vote
2 answers
220 views

How is New Shepard the first suborbital booster to successfully perform a powered vertical soft landing?

I saw this on wikipedia On 23 November 2015, after reaching 100.5 km (62.4 mi) altitude (outer space), the suborbital New Shepard booster successfully performed a powered vertical soft landing, the ...
phuclv's user avatar
  • 243
0 votes
1 answer
867 views

Terminal velocity on reentry?

I've seen many references to "terminal velocity" on reentry, e.g., prior to a Falcon 9 landing burn. And I'm confused by this. Because terminal velocity comes from drag which depends closely ...
user avatar
2 votes
2 answers
290 views

Falcon 9 vs Apollo Landing: Key Differences?

So I'm struggling to model a Falcon 9 vertical landing. And because Falcon 9 info is scarce, I'm looking for more public info sources---like the apollo missions. The Apollos did basically vertical ...
user avatar
3 votes
0 answers
147 views

Falcon 9: transonic attitude control on reentry

Attitude control on the falcon 9 is done with engine thrust vectoring, cold gas thrusters, and grid fins. After the reentry burn, when the rocket stage is in the atmosphere, there is a short period ...
user avatar
1 vote
1 answer
132 views

State vector update on reentry

The integration errors from IMU state measurements would seem very problematic when you're coming in for a landing, where error tolerances would probably be as small as they could get. This must mean ...
user avatar
2 votes
0 answers
1k views

Vertical Landing: Calculating start altitude for hoverslam landing burn

So I've been thinking about hover slam landings. I want to simulate one. This is the best I've come up with so far. It's all high school physics. Am I far off? Scenario Say you're landing a rocket ...
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1 vote
0 answers
81 views

Falcon 9: Landing leg helium pressure?

So it seems the Falcon 9 landing legs are powered by a helium precharge. Does anyone know the pressure of that precharge? If no numbers for Falcon 9, is there at least a reasonable range of what the ...
user avatar
1 vote
2 answers
621 views

Flying saucer shape rocket vs cylindrical shape rocket

Here's my hypothesis- Cylinder shaped large rocket is not suitable for vertical landing due to its high center of mass and bulky weight. However an equally weighing saucer shape rocket has more ...
seccpur's user avatar
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3 votes
0 answers
73 views

Falcon 9 Flipover Direction?

Consider a Falcon 9 at MECO. The rocket's close to 30 deg relative to the local horizon, down from the 90 deg it had at launch. Stage 1 separates and flips more or less 180 degrees for the return ...
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0 votes
1 answer
136 views

Falcon 9: How many engines on first burn in two-burn reentry?

Consider a Falcon 9 two-burn reentry maneuver. My understanding is that the second, final, burn is always single-engine. And I think the first burn can be either single-engine or three-engine. But I'm ...
user avatar
0 votes
0 answers
48 views

Falcon 9 legs: precharged helium?

I've read the Falcon 9 uses helium pneumatics to extend its legs. The separation pushers are also helium pneumatics and I believe those are precharged so no pumps required. Are the leg cylinders ...
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2 votes
1 answer
749 views

Hover Slam Landing: How is it Done?

I want to simulate a hover slam landing. Is there an overview of the maneuver anywhere? I'm especially interested in the control algorithm used to bring the rocket stage to a halt at just the right ...
user avatar
1 vote
0 answers
148 views

Falcon 9 Angle of attack on return flight?

Do they control for angle of attack on the return flight of stage 1 of Falcon 9? Once it reenters thick atmosphere, aerodynamic stresses would be a concern as during launch, maybe more so because you ...
user avatar
4 votes
4 answers
330 views

Alternative to GPS navigation for vertical landing, especially on other planets

Is the GPS data reliable or meaningful only on Earth or below the geo-stationary Earth orbit? For GPS navigation, does a rocket has to fly below the geo-stationary orbit? If GEO is a physical ...
seccpur's user avatar
  • 1,175
12 votes
2 answers
2k views

Falcon-9/Starship landing on an uneven surface

I was wondering how a Starship or Falcon-9 booster could land on an uneven surface, like that of the Moon or Mars. Is the landing gear similar to the Boeing hydraulic landing gear, which cushions and ...
seccpur's user avatar
  • 1,175
4 votes
0 answers
70 views

Atmospheric retro-propulsion performance of aerospike nozzles?

I’m thinking about the use of single toroidal aerospike engine for a reusable upper stage with propulsive landing capability and this question came to mind. Do aerospike nozzles even capable of retro ...
Aungmyintmyat Hane's user avatar
2 votes
1 answer
206 views

Controlling suicide burn landing location in a python simulation?

I recently asked a question in stackoverflow about Simulation of suicide burn in openai-gym's LunarLander. Sadly most of my assumptions about suicide burn implementaion were wrong but the answer given ...
Eka's user avatar
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9 votes
2 answers
5k views

What is the difference between a "Suicide burn" and a "Hoverslam"?

As far as I can tell, the terms Suicide burn and Hoverslam have both been invented rather recently (with SpaceX themselves coining Hoverslam and the Kerbal Space Program community loosely credited ...
Dragongeek's user avatar
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4 votes
1 answer
165 views

Could the SSMEs of the SLS do retro burns?

The SLS will use the main engines of the space shuttle. Are these capable of retro-burns in the upper atmosphere like SpaceX’s Merlin engines? More broadly, could the SLS’ main engines and ...
techSultan's user avatar
6 votes
1 answer
525 views

Why was the water-landed Falcon 9 B5-B1050 towed backwards for retrieval?

The rocket was apparently recovered by attaching a towing line to the heavy, lower end (with the engines) and pulling at backwards. This seems counterintuitive to me, as this pushes the water into ...
leftaroundabout's user avatar
2 votes
1 answer
117 views

Can VTVL rockets use dampers like high rise buildings to provide stability?

VTVL with long and thin body have a difficult time in obtaining stability during landing. Watch this failed SpaceX rocket landing for example: Why can't they use "...
jerrymouse's user avatar
37 votes
2 answers
6k views

Can a spaceship land on an icy body using retropropulsion? wouldn't the ice melt?

Can a spaceship, say Musk's BFR, actually land on the ice surface of Titan, or Europa, or Enceladus? It seems to me that the hot exhaust gases would make the surface melt where the rocket is trying to ...
thomasjestin's user avatar
19 votes
2 answers
4k views

More efficient SpaceX landings?

Although the exact trajectory of a rocket is not known before launch, could SpaceX position its landing barge even further down range of the launch pad and eliminate the need for a boostback burn ...
Jake Blocker's user avatar
  • 4,285
3 votes
1 answer
383 views

How would vertical landing scale with size - does bigger = "easier" (actually)?

This Ars Technica article has two titles that seem to be a bit gratuitous: Why Bezos’ rocket is unprecedented — and worth taking seriously Why Blue Origin’s crazy big rocket might fly, and what it ...
uhoh's user avatar
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