Space Things

[Irace86.2.0]

I was considering the first stage SpaceX Super Heavy's reentry:

https://en.wikipedia.org/wiki/SpaceX_Super_Heavy

0.5 million (250 US tons) pounds dry
7.4 million (3,700 US tons) pounds fuel
7.9 million (3,950 US tons) pounds wet/total

95% of the weight is in the fuel. I've read that the reentry fuel is estimated at 6.5-10% of the fuel, some of which might be residual fuel because you don't want to run out on reentry. At 10%, we are looking at 740,000 (370 US tons) pounds of fuel, which is significantly more than three 2,000 (1 US tons) pound parachutes, which would be an one-hundred fold savings.

Seems like SpaceX is considering this too, as the Super Heavy booster will be caught on a tower (if that is still the plan), and like the arresting wires slowing a jet on the landing of an aircraft carrier, the tower seems to have counter weights, hydraulics or magnets to slow the booster. Maybe this is the best compromise.

[Dadhawk]

Originally Posted by Irace86.2.0

Seems like SpaceX is considering this too, as the Super Heavy booster will be caught on a tower (if that is still the plan), and like the arresting wires slowing a jet on the landing of an aircraft carrier, the tower seems to have counter weights, hydraulics or magnets to slow the booster. Maybe this is the best compromise.

It is still under development as far as I know. The primary reason for the "catch" method is that Super Heavy doesn't have landing legs with shock absorption. The weight required for those would end up increasing the weight of the booster by some 10%, again requiring more fuel.

The directional fins at the top of the booster are strong enough to hold the entire booster as an artifact of the strength required for directional forces during landing. The booster also has enough power that it can effectively hoover during the transition.

[Irace86.2.0]

Originally Posted by Dadhawk

It is still under development as far as I know. The primary reason for the "catch" method is the that Super Heavy doesn't have landing legs with shock absorption. The weight required for those would end up increasing the weight of the booster by some 10%, again requiring more fuel.

The directional fins at the top of the booster are strong enough to hold the entire booster as an artifact of the strength required for directional forces during landing. The booster also has enough power that it can effectively hoover during the transition.

I would think it has enough power to hover. It launched the rocket after all.

So the tower saved some weight off the booster by being a shock absorber, and the booster isn't hovering because that is sketch and wasteful, so again, it acts as a shock absorber, but could it be more? Maybe they could make a giant magnetic catch system like Drop Zone. Seems like at minimum parachutes could reduce the speed to 50 mph before rockets finished the job.

The reusable payload is 100-150T, so there would be huge savings to the cost of flight by reducing the reentry fuel for the Super Heavy booster and Spaceship. The Starship has a dry weight of 120T and a weight weight of 1,320T with 1,200T of propellent. Ten percent of that is 120T, so if we are saving 120T from Starship and 370T from Super Heavy then we increase out payload from 100-150T to 600-650ish. This is a factor of 4-6x. For perspective, Falcon 9 was $67 million per payload, which had a capacity of 25T, but Musk says Starship will be around $10 million for the same 25T payload. If they could increase the payload by 4-6x then the price for the same 25T payload could drop to $1.5-2.5 million, doing rough math.

[Dadhawk]

Originally Posted by Irace86.2.0

I would think it has enough power to hover. It launched the rocket after all.

Well, to clarify it can hover with only the decent engines. Apparently, at least from what I read, Falcon 9 can't do that.

[Irace86.2.0]

This was well done, especially with all the great images.

[Unplugem]

[Captain Snooze]

This is f*cking incredible.

[Ultramaroon]

Originally Posted by Captain Snooze

This is f*cking incredible.

"If you haven't read this, shame on you."


I'm shocked at the glaring deficiencies he uncovered. Fascinating.

[Dadhawk]

Originally Posted by Irace86.2.0

This was well done, especially with all the great images.

I find it a little off-putting how "positive" all the SpaceX pundits continue to spin SpaceX failures that if NASA had done there would be an outcry of shut them down.

Calling this flight and "outstanding success" even though it didn't reach it's primary goal (orbital flight) and lost both the booster and Starship is less than unbiased reporting, yet all of them seem to follow SpaceX lead on this.

The launch was amazing and they received lots of good information from it I'm sure, but call it as it is. The flight failed.

[Dadhawk]

Originally Posted by Ultramaroon

"If you haven't read this, shame on you."

I'm shocked at the glaring deficiencies he uncovered. Fascinating.

I don't think he really uncovered them as much as brought them into the light. I've thought since day one it seemed overly complex, but obviously what do i know?

The one thing I found concerning for me was I learned from this was the lack of using a hypergolic fuel source for ascending from the lunar surface. Not that ignition systems fail that often but it just seems simpler. Complexity for no discernable reason.

I had also never seen the photo of the Apollo 1 crew praying over a model of the command module. That was unsettling.

[x808drifter]

Originally Posted by Dadhawk

I find it a little off-putting how "positive" all the SpaceX pundits continue to spin SpaceX failures that if NASA had done there would be an outcry of shut them down.

Calling this flight and "outstanding success" even though it didn't reach it's primary goal (orbital flight) and lost both the booster and Starship is less than unbiased reporting, yet all of them seem to follow SpaceX lead on this.

The launch was amazing and they received lots of good information from it I'm sure, but call it as it is. The flight failed.

To be fair though anything past actual separation this time was icing on the cake.
Same with the 1st flight where anything after it got off the pad was icing on the cake.
So technically they were "outstanding successes" but at the same time if considered from a was the flight complete it was a failure.
But both stages blowing up was also a huge step backward.
Have SpaceX been calling it anything but a failed flight? I stopped paying attention to them beyond the Starship trials after Elon said fuck YouTube I'm gonna only stream on twitter.

At least no vans died this time.

[Dadhawk]

Originally Posted by x808drifter

Have SpaceX been calling it anything but a failed flight? I stopped paying attention to them beyond the Starship trials after Elon said fuck YouTube I'm gonna only stream on twitter.At least no vans died this time.

I don't think SpaceX has ever called one of their flights a failure regardless of the results. That said, I didn't check.

[Dadhawk]

Originally Posted by x808drifter

To be fair though anything past actual separation this time was icing on the cake.
Same with the 1st flight where anything after it got off the pad was icing on the cake.

Why? The stated mission of the flight was to get to suborbital flight and recovery.

I agree it wasn't a complete failure, but I wouldn't call it a resounding success either.

[ZDan]

Starship lunar lander missions to require nearly 20 launches, NASA says
https://spacenews.com/starship-lunar...hes-nasa-says/

I never considered Starship a viable lunar lander. They were picked because lower price. This seems like a ridiculously impractical way to put humans on the moon again. 1x SLS launch at ~ same mass as Saturn V, plus upwards of *20* Starship/Superheavy launches at nearly 2x that mass each, 1 for the lander and the rest for refuelling? I mean, it's fricking absurd...