SpaceX Starship Orbital Flight Test

That’s quite a bit higher than the impression Truax gave me circa 1990, but then I never bothered to check up on his claim. In any event, I’m pretty sure the “TRW report” is the document I previously linked to. Here is The Money Quote:

To do an apples to apples comparison, we must use the before-amortization cost. Here’s Musk’s quoted target again:

“Musk has predicted that a Starship orbital launch will eventually cost US$ 1 million (or US$ 10 per kilogram.”

That doesn’t look like an amortized cost.

If so, the low end TRW estimate is $(2020)184, which is nearly 20 times Musk’s target.

That said, it still looks to me like Kennedy/von Braun really did a number on the US if not the world by failing to go with prize awards for milestones toward landing a man on the moon using guys like Truax and Hughes rather than a communist style “8 year plan”.


Marcus House has chimed in with his coverage of the flight. He does not go in for speculation about causes of things, but has some video of the launch I hadn’t seen before, including the SpaceX drone shot showing debris landing in the Gulf as the rocket ascends. There are still pictures from Starship showing some missing thermal protection tiles and the stages in the process of breaking up.


Scott Manley is normally an astute observer, but he was probably a bit off in suggesting that the +/-150 feet water depth where the rocket came down is too deep for amateur divers. All SpaceX has to do it get those 4 men & a chick on a rented sailboat who blew up 3 out of 4 NordStream pipelines in significantly deeper water in the Baltic. Those Ukrainians will have the remains on the rocket back on dry land in no time flat!

Of course, it might be difficult for SpaceX to get in touch with those wiley Ukrainians. No-one else seems to be able to find them.


Musk believes he has the stage zero in hand.


The water cooling of the steel plate will be open loop rather than closed loop. This begs the question of the discharged water. It would have to be steam, which will probably be classified as a pollutant by the EPA.

Perhaps musk can come up with a way to deflect ice falling from the rocket to help aid in the process.


The methane heat of combustion flow of just one Raptor is >7GW or ~250GW per Superheavy.

I’ve heard stuff like “as much power as the entire US electrical grid” associated with big rockets so – ok – about a quarter terawatt must be cooled by the water flow. Sheesh… ok… so that’s, what water mass flow rate?


'Zat rite?

(See, Calchemy still comes in handy 25 years after doing all those thermal calculations for the ultracentrifugal rocket engine!)

*Note this assumes steam is the output which must be carefully weighed against the fact that the thermal transfer properties of steam are far less favorable than liquid water. You really have to be careful about hot spots forming if you are relying on the total heat of vaporization. Things can get out of hand. You like to keep things liquid. It’s like, a really big deal at these areal powers.


The existing water deluge systems for SLS, Falcon 9/Heavy, and Atlas all emit huge clouds of steam into the atmosphere and nobody seems to bother about it. Of course, this is clown world where CO₂ has been classified as a “pollutant”, so you never know….


For comparison, the NASA water deluge system used for SLS launches, called the Ignition Overpressure Protection and Sound Suppression (IOP/SS) system is said to release 450,000 gallons of water over a period of 60 seconds. Here is a test of the system without the mobile launcher in place. As NASA noted at the time,

A geyser occurred because the mobile launcher was not present at the pad. When the mobile launcher is sitting on its pad surface mount mechanisms, the rest of the IOP/SS system is connected to the pad supply headers and the water will flow through supply piping and exit through the nozzles.

From this, Units Calculator says:

((450000 gallon) * waterdensity) / 60 seconds = 28.39 tonne/second

Given that Super Heavy has around twice the liftoff thrust of SLS, this seems consistent with your estimate of 100 tonnes/second.


Here is a comparison of Starship, Space Shuttle orbiter, and Cargo Dragon (original version) to scale.


If, as I surmise might well be the case, cooling steel plate must avoid phase transition to vapor in order to avoid hotspots, the output could be 100C liquid water (or thereabouts). One can minimize the amount of liquid water dumped into the environment by keeping things under enough pressure during contact with the steel plate that upon contact with atmospheric pressure, it immediately vaporizes. In that event the pressurized liquid water in contact with the steel plate should go well above 100C. The pressurizing pumps for this would need to be pretty powerful. I don’t have a handle on how powerful. I encourage the use of Calchemy for this kind of stuff:

PS: The copyright holders of Calchemy finally gave up supporting it because no one but me was using it. That’s why I salvaged a copy for my own use. This calculator really deserves a better home than I can give.


Were there not videos circulating showing an elevatable work platform under the launch structure? Used to help crews install/replace engines. Wonder what happened to that?

Since the intent is eventually for Starship to have a high launch cadence, it looks like one of the key lessons of this first flight will be the need for a very effective flame/exhaust diversion system. Maybe a complete redesign of the launch/retrieval tower?

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Regarding the steel plate as a combustion chamber wall is kind of interesting. The “chamber” pressure is less than 200psi even if all pressure is projected to the circle directly under the rocket.

Does this mean the cooling channels could do film cooling into the chamber?


Depending on the mix (kinetic vs thermal) of the energy to be diverted this would increase the pressure on the chamber from all that superheated steam on the flame side of the chamber. And if your cooling channels weren’t at a high-enough pressure over the chamber, you could get “chugging” instability that could, in turn, destroy the system including pumps.


Here is video from the launch taken by rocket photographer Trevor Mahlmann. This video is notable in being a single take that shows the rocket from launch to destruction, capturing the experience of an observer nearby. The sound is superb, with the low frequency rumbling and rarefaction to vacuum crackling not heard since the last launch of a Saturn V in 1973. The flares as “events” occur during the ascent are particularly obvious in this view.


That would be an interesting design, as the cooling water within the “hot plate” would never interact with the exhaust plume. My understanding is (but I have been able to find very little information about this on-line) is that in the original design for Launch Complex 39, the deluge water which did not flash to steam was captured in two holding ponds adjacent to each launch pad. This was presumably to allow the water to be separated from the unburnt RP-1 from the exhaust plume since the Saturn V engines ran fuel-rich and had a very fuel-rich turbopump exhaust as well.

This shouldn’t be an issue with Starship, since methane that mixes with water will presumably come out of solution spontaneously, after which the water can be released into the Gulf. However, even if internal water cooling is sufficient for the blast diverter plate, they still probably will need water sprayed into the air by “rainbirds” to suppress acoustic energy from the engines. Most of this will flash to steam, but not all.


Not knowing anything about the acoustic dampening physics here, but could the “film cooling” adequately substitute for “rainbirds”? This is quite a film: mass flow rate of up to 100tonne/sec water coming out of the cooling channels of the “chamber”. That water then expands to steam volume by a factor of up to around 1000 or a total volume flow rate for the steam of up to 100,000m^3/sec.

That’s a lot of gas flow but better that than concrete shrapnel.


These appear to be later/smaller ponds ued for leakage from fueling:

Also see p. 195 of this .pdf:

The RP-1 facility consists of three 86,000-gallon (577,000-pound) steel storage tanks. a pump house, a circulating pump, a transfer pump, two filter-separators, an 8-inch stainless steel transfer line, RP-1 foam generating building and necessary valves, piping, and controls. Two RP-1 holding ponds, 150 feet by 250 feet with a water depth of two feet, are located north of the launch pad, one on each side of the north-south axis. The ponds retain spilled RP-1 and discharge water to drainage ditches.


I don’t know how the sound suppression actually works. They all seem to spray water into the air in the vicinity of the exhaust plume, and I’ve heard it described as “dissipating acoustic energy by breaking up big droplets into smaller ones”, but I don’t know if that is the primary mechanism they’re employing.




Looks like Mechazilla held up fairly well. Seems like the civil engineering was the Weakest Link.


What will this do to future “environmental impact” assessments?