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Tom Kalbfus

Banned

Registered: 2006-08-16

Posts: 4,401

Falcon 9 lands safely on ocean platform

https://www.yahoo.com/news/inflatable-h … 12610.html


I think the key to a Mars colony is the reusability of the vehicle to transport the colonists there. After all, in order to be successful, the colonists have to be able to afford to go, they need to be able to perform some economic activity to support themselves on Mars, otherwise it is just government sponsored "flagpole sitting". The Government can send 100 people to Mars at a cost of hundreds of billions of dollars, the government can support them at taxpayer's expense, until the public grows tired of supporting them, but with current throw-away rocket technology, such a colony will never be successful. We need a non-throwaway space vehicle. What spaceX pulled off today is a step in the right direction.

tahanson43206

Moderator

Registered: 2018-04-27

Posts: 19,365

Re: Falcon 9 lands safely on ocean platform

In a topic about Starship, RGClark asked a question about left over propellant at landing.

It turns out quite a few people have asked the same question about Falcon 9, which does ** not ** have a problem with fires at landing.

The amount of propellant left in a Falcon 9 rocket at landing depends on where it lands:
Drone ship: 5,500 kg (12,100 lb)
Launch site: 3,500 kg (7,700 lb)
The Falcon 9's nine Merlin engines are used to decelerate the rocket for landing, reorient the first stage before reentry, and limit acceleration during the first stage of flight. The booster can be reused more than 10 times with minimal maintenance between flights.
Falcon 9 - SpaceX
The nine Merlin engines on the first stage are gradually throttled near the end of first-stage flight to limit launch vehicle acce...

SpaceX
Falcon 9 - Wikipedia
* FT: 8,300 kg (18,300 lb) when expended, 5,500 kg (12,100 lb) when landing on drone ship, 3,500 kg (7,700 lb) when landing at la...

Wikipedia
Boosting rocket reliability at the material level | MIT News
Nov 28, 2023 — Powered by SpaceX's Merlin engine, the Falcon 9 booster can be reused over 10 times, with minimal maintenance between ...

MIT News
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56.3 tons
Second, drone ship landings. These have (again on average) 27.1 tons of fuel left. Falcon 9's starting propellant is 409.5 tons so this gives us 4.4%. Finally, when landing on land Falcon 9 averages 56.3 tons.Dec 10, 2018

Falcon 9: how much fuel is left on a booster after stage ...

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How much fuel does the F9 FT really need to land?

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For DPL, about 41t remained at MECO, and 4t remained at landing. So 37t (9%) was used. (Simulation of Formosat-5).
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tahanson43206

Moderator

Registered: 2018-04-27

Posts: 19,365

Re: Falcon 9 lands safely on ocean platform

For all... This topic is available if anyone can find documentation of how SpaceX handles propellant after landing of Falcon 9.

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tahanson43206

Moderator

Registered: 2018-04-27

Posts: 19,365

Re: Falcon 9 lands safely on ocean platform

Here is a bit more about Falcon 9 ... apparently the unused propellant is vented to the atmosphere.

That means methane not used to make CO2 is vented straight into the Earth's atmosphere.

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After landing, SpaceX typically drains the remaining propellant from the Falcon 9 booster by using a system of valves and lines to vent the leftover fuel and oxidizer, essentially emptying the tanks before the booster is transported back to the launch site for inspection and refurbishment, allowing it to be reused on future missions.
Key points about propellant handling:
Purpose of draining:
This process is crucial for safety and efficiency, as leftover propellant could potentially be hazardous if not properly managed and could also add unnecessary weight to the booster during transport and reuse.
Procedure:
Once the booster lands, SpaceX engineers activate a system to carefully release the remaining propellant, often controlled by onboard computers to ensure a controlled and safe venting process.
Reuse focus:
By effectively draining the propellant, SpaceX can maximize the reusability of the Falcon 9 first stage, which is a key component of their launch system aimed at reducing launch costs.
Falcon 9 - SpaceX
Merlin. ... Merlin is a family of rocket engines developed by SpaceX for use on its Falcon 1, Falcon 9 and Falcon Heavy launch veh...

SpaceX
SpaceX reusable launch system development program - Wikipedia
Reflights of refurbished first stages then became routine. In May 2021, B1051 became the first booster to launch ten missions. The...

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SpaceX pulls off unprecedented feat, grabs descending rocket with ...
Oct 14, 2024 — SpaceX perfected first-stage landings with its workhorse Falcon 9 rockets, successfully recovering 352 such boosters t...

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GW Johnson

Member

From: McGregor, Texas USA

Registered: 2011-12-04

Posts: 5,796

Website

Re: Falcon 9 lands safely on ocean platform

The Merlin engines that power all the Falcons are LOX-kerosene engines.  It is the Raptors that power Starship/Superheavy that are LOX-methane engines. 

Methane leaks very easily,  almost like hydrogen.  It also ignites very easily,  almost like hydrogen.  Handling it is quite different from handling kerosene.  You have to handle it about as carefully as you do hydrogen.  It's a lot worse about leaking and fires than propane.

GW

---

GW Johnson
McGregor,  Texas

"There is nothing as expensive as a dead crew,  especially one dead from a bad management decision"

tahanson43206

Moderator

Registered: 2018-04-27

Posts: 19,365

Re: Falcon 9 lands safely on ocean platform

For GW Johnson re #5

Thank you for the correction!  I suspect the "elephant in the room" that RGClark is worried about may be methane.

I deduce that the technical/engineering problem faced by the Starship designers is far worse that was the case for Falcon 9, and that was difficult enough.

No one has ever attempted a vertical landing of a ship powered by methane before SpaceX decided to give it a try.

If you were a member of the Starship design/engineering team, I imagine you'd draw upon your experience (and that of others you've known) to try to reduce leakage of methane from the countless valves and joints where if escapes during a flight.

Vibration of the booster must be extreme during powered flight.  It seems possible to me that vibration is NOT a friend of valves or joints.

***
In this next section I will draw upon a completely unrelated field (where methane is studied) .... In this field (which has nothing to do with rockets) methane is studied in real time to find leaks.  I saw a video showing operation of equipment that is (somehow) able to "see" methane via electromagnetic signals.  The report about this technology was for the general public, and it did not offer any details whatsoever as to how the equipment works. The report was focused upon showing that in the hands of a trained operator, the equipment ** can ** show methane leaks.
***
So here's my question.... if equipment able to "see" methane is added to the engine bay of a Starship booster, could SpaceX identify locations where leaks are occurring?  At the very least (assuming the answer is yes) it should be possible to send the data to SpaceX for later study.
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GW Johnson

Member

From: McGregor, Texas USA

Registered: 2011-12-04

Posts: 5,796

Website

Re: Falcon 9 lands safely on ocean platform

I honestly don't know the answers you seek.  Anybody who claims to "see" leaking methane has something new.  It may be a while before that clam can be trusted. 

GW

---

GW Johnson
McGregor,  Texas

"There is nothing as expensive as a dead crew,  especially one dead from a bad management decision"

tahanson43206

Moderator

Registered: 2018-04-27

Posts: 19,365

Re: Falcon 9 lands safely on ocean platform

For GW Johnson re #7

I accept the challenge you have offered, to try to find the original source of the report I saw.  The report was generally about methane leaks, and this equipment was just one focus of the video, but I paid close attention (for some reason). The equipment is (apparently) able to (somehow) illuminate methane so that it stands out in a wispy way, against a background of nitrogen gas.  The equipment looked ** very ** expensive, but it did a lot more than just show methane leaking.

I'll start a methane leaks topic. The topic is (probably) RGClark's "elephant" so it's (probably) worth it's own topic.

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