Space and Science BS Thread

Not at all. They can "static fire" test the ring on it's way to orbit.

 

FIFY

 

Maybe they’ll list all if his accomplishments with BO.
https://x.com/lorengrush/status/1706408228806885596?s=46

 

Whatever you want to call it the dome won’t be protected by any deluge system nor have any meaningful separation from the center engines. Kinda blows my mind that they wouldn’t test it prior to launch if they do plan to hot fire all 6. In all other Raptor tests they go to pains to avoid blocking the nozzles but for this it’s suddenly a great idea? Maybe they have enough data to do a convincing computer model which only reminds me of the old saying about statistics allowing you to err with confidence. Thrust/weight ratio might be why they would HAVE TO use all 6 since the booster will be almost empty but still thrusting on at least 3 engines @ 40% while the ship is full and only 6 available. At separation the ship might weight 4x as much as the booster. Without the added thrust the ship wouldn’t be able to get away from the booster
dry weight of booster 200 t
loaded weight of ship 1300 t
40% minimum throttle
*Normalize booster mass at separation to 1 and ship to 4 you get:
#of engines(thrust as a fraction of full)/weight
3(.4)/1 = 1.2 thrust/weight for booster
6(1)/4 = 1.5 thrust/weight for ship
But if you don’t have the extra center 3 it drops to:
3(1)/4 = .75 which is less than the booster.
*This assumes ~ 4% propellant mass left in booster tanks and I’ve no idea what it really will be and obviously won’t be needed for oft-2 but consumption at full power is 650 kg/sec and will need enough for boost back, decel, and landing burns for the 3(?) engines used. I checked the data for F9 and found 13.7% for rtls, 4.4% down range drone ship, and 2.2% for fully expended.
https://space.stackexchange.com/questions/32751/falcon-9-how-much-fuel-is-left-on-a-booster-after-stage-separation#:~:text=These have (again on average) 27.1 tons of,is 409.5 tons so this gives us 4.4%.
It’s much worse fully expended than rtls. With a 13% propellant load at separation the booster almost doubles in mass over a 5% load (~640 t vs 370 t) which is just barely enough for a 3 engine ship to get away. Fully expended they’ll get the ship away with all 6 but not very quickly.

 

https://x.com/squigglyvolcano/status/1705751416772411501?s=46

 

Re: my previous post I wonder if they’d consider the gimbal release method in addition to hot staging. It might speed both separation and booster turn around.

 

They gimbal the booster engines to kick it free of the ship. Since the ship has way more mass at this point it’s trajectory is unaffected but the booster gets a lateral movement that begins the boost back turn. Or something like this.

 

#theydidthemath

I will say that the dome will only have to experience about 2 seconds of fire at an unknown throttle percentage. Also, they will be gimballing the center 3 out towards the outer edge of the ring so they won't be straight on firing into the dome. In addition, the center 3 have more than a meter of space between the end of the nozzle and the bottom of the engine compartment, and probably another meter between the bottom of the engine compartment and the top of the dome. The top of the dome is below the top of the HSR.

 

The amount of time and effort you guys spend analyzing data points you should be working for spacex making 100k+ a year...

 

I would love to make $100k+ a year, but I'm sure SpaceX already has people doing the armchair engineer thing.

 

They do. They need welders, grinders, manual labor, etc.

 

And those guys are working 70+ hours a week to do so. There is a reason the average tenure at SpaceX is less than 2 years. I work out at Vandenberg and have talked to plenty of techs who regularly do 12+ hour days 6 days a week. Great on a resume, just not conducive to any kind of work/life balance

 

You currently work at Vandenfog? Can you please suggest giant fans to blow the fog away for launch views?

 

So cool:
https://x.com/nasaspaceflight/status/1707067774537781625?s=46

 

https://x.com/mastronomers/status/1707114176487760307?s=46

 

Who remembers New Shepherd?
https://x.com/spcplcyonline/status/1707146216109232484?s=46

 

https://twitter.com/m_tijn/status/1707098896378282187?t=Yxhp42r0DULVyiHwabiWkg&s=19

For @bagleboy...

 

Almost as much fun as a Monday morning QB and equally worthwhile but still entertaining. Speculation fills the time.