New Mars Forums

And there is still another elephant in the room being ignored.

Bob Clark

Question: how much payload can Starship V3 get to orbit?
Answer: don’t ask, don’t tell.

Bob Clark

Now that Starship is presumably operational it will have to give what its payload capability is as fully reusable.

  Bob Clark

To quote that great home-spun philosopher Lt. Commander Montgomery Scott, “Fool me once, shame on you. Fool me twice, shame on me.”

Bob Clark

Thanks. I'll take a look at that. One key economic issue is needing He3 from the Moon to run them.

  Bob Clark

GW, your and Dr. Akin’s separate analyses both suggesting 800°C peak temperature gives confidence it is valid. The problem is there is a discrepancy with an actual LEO reentry experiment at low ballistic coefficient. The experiment was called LOFTID and used an inflatable heat shield:

What was the ballistic coefficient of the LOFTID demonstrator and what was peak temperature?
The ballistic coefficient of the Low-Earth Orbit Flight Test of an Inflatable Decelerator (LOFTID) demonstrator was 24.7 kg/m², and the outer surface of its heatshield reached a peak temperature of approximately 1,500°C (2,700°F) during atmospheric reentry. [1, 2]

Key Flight Demonstration Metrics
NASA's LOFTID Mission successfully validated hypersonic inflatable aerodynamic decelerator (HIAD) tech with the following flight data: [1, 2, 3, 4]
* Entry Mass: 1,100 kg
*
* Aeroshell Diameter: 6 meters (fully inflated)
*
* Peak Heat Flux: ~40 W/cm²
*
* Peak Deceleration: 9.5 g
*
* Entry Velocity: 8 km/s (approx. Mach 30) [1, 2, 3, 4]
*
The vehicle's second-generation flexible thermal protection system (F-TPS) featured an exterior ceramic fiber cloth designed to survive environmental limits up to 1,600°C (2,900°F), comfortably protecting the structural inflatable rings from the peak heating experienced during the test. [1, 2]
If you would like to explore this topic further, I can provide more details on the layer composition of the flexible thermal protection system or compare LOFTID's metrics to previous suborbital tests like IRVE-3. Let me know what you would prefer! [, 2]
https://www.google.com/search?q=What+wa … emperature

The ballistic coefficient of ~25 kg/m² for a 6 m wide decelerator was in the range comparable to both yours and Dr. Akin’s. But the peak temperature was nearly twice as high at 1,500°C.

The shape was different in being a flattened cone, while yours and Dr. Akins was a portion of a sphere but I wouldn’t think the difference would be that big.

NASA Successfully Tests LOFTID Inflatable Heat Shield.
https://www.youtube.com/watch?v=9mM1JIPY4Mw

   Bob Clark

I watched the Nasaspaceflight broadcast of what was supposed to be a static fire. It didn’t occur. There was then discussion among the hosts of what exactly happened since there was no flame produced. At first they thought perhaps it was just a spin prime test. But it was just too little gas produced underneath the rocket to be a full spin prime so maybe even that had to be curtailed.

SpaceX is now in a difficult position. They know from the prior try at a static fire back in March that had to be rapidly aborted that this damages the engines:

https://x.com/grok/status/2080393370753528136?s=61

It is likely last week’s rapid abort of a launch attempt also damaged engines. But was it really only two engines being replaced in this case as Elon first said? The difficult position they are in is it would be time consuming and detrimental to the public view of the Raptor reliability if all engines had to be replaced, and especially in the stock markets view.

But then now even a spin prime test was not successfully completed. Despite what SpaceX portrays to the public, they know the Raptor is not reliable under multiple starts. So they don’t even want to risk another static test.

Then, this is now going to be the riskiest launch attempt since the very first test launch of the Starship.

  Bob Clark

Looking at the stage separation of flight 12 there was something definitely out of the ordinary. The booster appears to have been blasted on its side by the Starship engines near where the grid fin is. I don’t remember seeing that on the videos of the other stage separations. Usually the ship exhaust only impacts the top of the booster where, presumably, it is reinforced.

See it here in this Scott Manley video at about the 11:30 point in the video comparing flight 11 and flight 12:

https://youtu.be/2kxanBYTAaY?t=691&si=yynBCm5U-383E3B9

I wonder if this could have caused a tank over pressure that could have damaged the booster engines.

Another possibility occurs to me. The view angle blocks the view of the booster around the time when the flame appears on the side of the booster near the grid fin, so you can’t quite tell where the flame originates from. But it actually looks like the flame may emanate from the booster. Slow the video down to see it more clearly. This would mean there is a methane leak from the booster tank. This would be a pretty serious failure if it is the case. But it would explain the flames seen dancing down along the sides of the booster.

Bob Clark

Below I present argument why there is bad engineering in the SpaceX development of the Starship. In a follow-up post I’ll explain why SpaceX has a solution right in front of them but they refuse to implement it.

___________________________________________

The SpaceX Starship is bad engineering. All through the early, prior tests of the Starship’s hovering and landing procedures, i.e., before the current flight tests, the Raptor version 1 would routinely leak fuel and catch fire. When SpaceX began the actual flight tests, the Raptor 1 and Raptor 2 continued to leak fuel and catch fire, sometimes even exploding in flight.

After a mishap investigation of one of the test flights, the FAA required SpaceX to fix the leaking fuel issue. But SpaceX really did not fix it. What they did is add additional fire shields and firewalls. This served to obscure the fact the Raptor still routinely leaked fuel and caught fire, and still sometimes exploded in flight.

Now we’re at Raptor 3 and the 12th test flight and the Raptor still leaks fuel and catches fire or outright explodes in flight. That’s bad engineering. A Raptor on the booster exploded taking out neighboring Raptors. And on the Starship, some “energetic event” at the 3:09 point in the flight on a vacuum Raptor caused it to shutdown. The Raptor did not explode in this case but an interior shot of the engine bay showed once again a Raptor was leaking fuel. If it had been allowed to operate it’s clear it too would have caught fire or exploded in flight.

This causes a problem for SpaceX and for NASA. The reason this is bad for SpaceX is there is no way NASA is going to qualify the Raptor for manned flight when it routinely leaks fuel and either catches fire or explodes in flight, no matter how many firewalls and fire shields SpaceX deploys obscuring that fact. It’s bad for NASA because NASA hopes to use the Starship as a manned lander for the Artemis program.

But the Raptor has been in development for over 10 years and has had this continuing leaking fuel problem all during this time even until now. SpaceX is unlikely to be able to solve it in 2 years when it has been unable to solve it during the over 10 years of Raptor development.

As I see it there are only two possible explanations as to why NASA continues to treat the Starship as a viable option for a manned lunar lander:

1.)By using fire shields SpaceX obscured the fact the Raptor continues to have the problem of leaking fuel and catching fire and never informed NASA of that fact.

2.)NASA was aware of the fact the Raptor continues to have the problem of leaking fuel and catching fire but never informed the public of that fact.

I don’t know which of those two possibilities is worse.

Image showing the “energetic event” that caused one of the Starship vacuum Raptors to shutdown.

This video clip of the interior of the engine bay shows a vacuum Raptor, the one shutdown, leaking fuel:

What Exactly Happened On SpaceX's Twelfth Starship Flight Test?
https://youtu.be/NusIDi9Iu-M?t=257&si=JhwaX_oavromCl0O

Bob Clark

My criticisms about SpaceX previously were about disagreements on engineering decisions. However, there has been commentary on social media that last weeks fatal accident was due to reasons other than what SpaceX has revealed:
__________________________
Space x Update: (Sent By Space X Worker)

Good morning. Here is an update and clarification regarding the accident that happened at SpaceX.
According to workers at the site, the victim was reportedly a contractor employed through a third-party construction company, not a direct SpaceX employee. Workers say SpaceX employees go through extensive safety training and OSHA monitoring, while contractors operate under their own company’s management and safety enforcement.
The most consistent information we have so far is that a beam was being moved by a crane while a worker was on a lift nearby. The beam reportedly fell, struck the lift, and caused the worker to suffer fatal injuries. CPR was attempted, but unfortunately the 25-year-old worker died at the scene. The construction company involved has reportedly not released details while the incident is being investigated.
The major question being raised is why a worker was allowed to be on or near a lift while a suspended beam was actively being moved. Standard construction safety protocols are meant to keep workers clear of suspended loads due to the obvious risks involved.
If the reports are accurate, there will likely be investigations into safety procedures, contractor oversight, and responsibility for the incident. Prayers to the worker’s family and everyone affected by this tragedy.
__________________________
https://www.facebook.com/share/17CRC3Zs … tid=wwXIfr

Granted this is a social media posting so its validity needs to verified. But SpaceX has only said he fell 8 feet from a scaffolding. That in itself seems suspicious. But if the scaffolding, or the worker himself, was hit by a falling a beam that could increase the chance of a serious injury.
This is an important distinction because OSHA has strict guidelines when workers can be within the vicinity of heavy objects being lifted by cranes. Last years crane accident also being operated in an unsafe fashion resulting in injuries gives credence to the idea this may indeed have been what happened.

  Bob Clark

Glad to see New Mars back. Could you provide a link to those images?

  Bob Clark