Like Hyperloop, Starship has some fundamental issues in it’s design and it’s proposed modus operandi that make the system not just impractical but an absolute engineering failure, incapable of ever actually working as proposed.
I remember the first proposal of starship well. I had popcorn.
After Boring Co had just failed to deliver a working Hyperloop test They began silently scaling down development of hyperloop and removing the proposed city projects for hyperloop and hypertunnel from the Boring co website in 2019. Hyperloop and hypertunnel represented billions in investments and development deals that Boring co has lost entirely.
Elon musk needed a win. Enter the Starship presentation.
It was a presentation so important, The SUN was chosen to cover it all.
During the presentation, Elon musk himself described the entire flight plan and even structural elements proposed for this gigantic super heavy extra orbital VTOL spacecraft.
Some notes on the engineerig and stress factor issues.
-301 stainless is the steel that spacex is using for the fuselage.
Remember that as more of these explode, shed parts and rupture in future testing.
Cryogenic structural supplementation: Things tend to become MORE brittle, the more you cool them. This is why engineers tend to rely on stronger materials with a wider thermal spectrum, like titanium rather than cryo to try making everything rigid enough. It also explains how an entire fuselage will shatter into small fragments and extend the range and effect of explosive combustion at the slightest jolt or compartment explosion when touching down as we’ve seen every single time starship explodes. By contrast Nasa’s DCX (nearly 30 years ago) could sustain an onboard explosion without ripping itself to shreds and perform far better VTOL operations.
Starting at 15:00 in the video, (if you can resist pausing to facepalm every time Musk makes a childish narrative, stammers more or says something idiotic) he goes over re-entry and fuel payload.
NOW, add math.
Mainly the resistance factor against the orbital speed.
Musk claims 301 steel has a melting point at 1600c. This is bullshit, it is actually 1420c if you are lucky.
–Note, he also claims CARBON FIBER has a lower melting point than 301 steel. That is also bullshit, Carbon fiber melts at 3652c
*Reentry temperature at full speed is 1649c.
He then states that one layer of heat shielding surrounds and protects this system. So with shielding, cooling and a burn to slow re-entry, there is a temperature and speed gap which needs to be closed before you blow up hitting the atmosphere. In cooling the structure, you are actually adding to how brittle and weak the structure is so you then need to slow the craft that much more to lower friction.
The slowing process would need to take place before the craft makes contact with the atmosphere, preceded by a full rotation of the craft from a long and costly burn to slow down.
The orbital speed is 17,500mph if launched from the surface and orbiting and in excess of 25,000mph if travelling from the orbit of another body beyond earth.
In order for Musk’s idea to work as described, the craft would need to arrive at or below mach 2 upon reentry. Faster than the speed of sound but not so fast that the smart flap system being employed would not be totally useless during the dead stick free-fall after the craft has burned away virtually all of it’s fuel just to slow down.
Mach 2 is 1534mph.
So that burn to slow the craft will have to take it From 17500mph to 1534mph.
GRANTED, re-entry alone takes care of some of this speed, with tons of friction and heat but you are still hypersonic after the full transition.
Which means you need to slow down before reentry. *noting at this point that we have now created more technical and structural issues than if we simply used titanium alloys and carbon fiber.
At this point hyperloop is almost a more logical and practical hypothesis and we knew that to be bunkum tech over 80 years ago.
Another issue with starship’s re-entry is that spacex plans to slow the craft more during re-entry by exposing as much of it’s surface as possible to the process. Instead of entering in the lowest exposure/resistance possible as the space shuttle did, starship would be as elongated as possible while re-entering in an attempt to create more resistance and slowing.
Remember that in the ORIGINAL presentation, Musk implied that the ENTIRE fuselage would be covered in heat shielding.
But in recent images of the craft, we see that spacex has stopped installing heat shielding at only the (intended) re-entry side of the vehicle, (not unlike the space shuttle) with heat shielding.
Starship will be be fully exposed to re-entry, traveling far slower and with only HALF of it’s ROUNDED fuselage protected by heat shielding.
The amount of heat hitting the unshielded portions of the vehicle will be well in excess of the melting point of 301 stainless steel not even half way through it’s initial re-entry.
To say nothing for the heat that will collect in the rear of the vehicle as it too will be fully exposed at an inefficient angle and inducting heat directly onto the engines.
Weve seen how hot it gets inside the engine compartment during it’s slow sub orbital tests.
Add the heat of re entry to this massive induction well at the rear of the craft and inside its engine compartment.
The post re-entry and landing issues
If starship ever happens to make it though re-entry, we have the dead stick free fall and VTOL landing issues to deal with.
In the first test, if starship is even able to return from orbit, spacex plans to plash it down in the ocean and then retrieve it by boat.
It’s proposed operations however indicate that it will eventually be able to land vertically on a specified pad on the land, not unlike the falcon 9 boosters.
Returning a sub orbital rocket or jet craft to the ground is a simple task. The air force and NASA have been doing it for decades.
Starship however, intends to do this after traveling at and beyond earth’s orbit.
The problems with orbital VTOL:
Falcon9 boosters never reach orbit, orbital speed or leave the atmosphere. They can easily return from a controlled fall to a VTOL (Vertical Take-Off & Landing) landing at these low speeds and having only left the ground in a direct limited arch.
After re-entry, starship will have almost no fuel left and be in a dead stick (no power, flap only control) free-fall for over 60KM until it reaches the area (below 20km) where it is supposed to re-ignite it’s engines, orientate itself and burn off the last of it’s remaining fuel (if any is left) to perform a pin point VTOL landing.
Starship’s flaps are very small. Taking up less than 5% of it’s surface area, separated along the fuselage and limited by control to resist force. The ship has no dorsal control fin or flaps.
Not only do Falcon9 boosters travel slowly upon return from a sub orbital path but they also have the benefit of grid fins which act as air brakes to better direct and control their fall which is vertical as apposed to horizontal as starship is proposed to descend. Grid fins are a concept that Spacex borrowed from the US Air force’s smart bomb systems like the MOAB.
The primary reason the space shuttle had a long and wide wing span was to give it the ability to glide in free-fall while travelling horizontal. Thus allowing it to be somewhat free from orbital lock/return and select more areas to land if needed. With a long enough runway, the space shuttle could land at virtually any airport under it’s re-entry window.
Having a far greater area to select for landing allows re-usable space craft to be more versatile.
Starship’s re-entry from orbital lock (the path any orbiting object is locked into taking around any body while in orbit and before re-entry) is limited greatly compared to the space shuttle due to it’s method of re-entry which is sloppy and chaotic by comparison to the space shuttle.
It’s lack of a dorsal control fin and the limited size and capability of it’s four small control fins (Airelons) will only allow for very limited control in it’s free-fall.
It may be able to keep itself at somewhat controlled horizontal and vertical angles (pitch, yaw and roll factors) but there will be absolutely no lateral control and no ability to glide at any more than a very limited degree. It will be falling straight down and subject to variables in atmospheric pressure, wind and cloud cover which will add MILES of uncontrollable course changes. With over 60KM of free-fall, those variables stack up and add a massive amount of change to direction that starship will have ZERO control over.
If the intention would be to land it on a specific pad in a specific area the system has already failed.
You might as well be firing a slug from orbit with a conventional non rifled two barrel shotgun and intending it to land on the bullseye of a bar dart board on the ground.
This is the primary issue with the VTOL concept when you attempt to apply it to an orbital vehicle.
They work fine for booster returns from a direct line of travel and controlled free fall as with falcon 9 and similar systems that The air force and NASA have been operating since the 1990’s.
But When you include orbital and trans-orbital operations, the system becomes useless and counter productive.
You eliminate a variety in landing areas and safety not just in high gravity but for low gravity landings as well.
The low gravity landing issue
If you attempted to land a starship on the moon, you would face issues with the vehicle toppling or falling over while attempting to set down a heavy lander in a law gravity environment. NASA’s original concept for the moon lander was a massive vehicle with a vertical span that was larger than it’s landing area. NASA soon realized that trying to land something with less landing surface than it’s vertical size in a low gravity environment would make the vehicle prone to topple and roll over wile violently trying to correct for the release of inertia.
Which is why NASA later developed a smaller lander with a larger landing surface than it’s vertical area.
Since Starship would have no precision in landing area, this means that spacex will have to either abandon the project entirely, or re-draft starship as a space plane concept not unlike the space shuttle.
For lunar landing, Spacex will need to redraft an entirely new vehicle capable of safely landing in low gravity.
If spacex wants to actually get ahead of the game or build anything new or diverse compared to anything that has been done before, they may want to start developing a fully reusable space plane like the Skylon which Reaction Engines Limited is currently developing in the UK.
In fact I am confident that if Spacex does not go out of business entirely within the next five years, they will redraft starship as a space shuttle or skylon style space plane.