Starship “EP2P” (Earth Point-to-Point) Discussion

[mongo]

Interestingly, Space Tourism seems to be much less regulated than commercial airline operations (121 being related to the operation of an air carrier, and not the actual airplane).
For example: 460.45 3 (b) calls out:

An operator must inform each space flight participant that the United States Government has not certified the launch vehicle and any reentry vehicle as safe for carrying crew or space flight participants.

Link to regulations:
eCFR — Code of Federal Regulations
Reusable Launch Vehicles are covered under
Title 14 → Chapter III → Subchapter C → Part 431
Reentry Sites:
Title 14 → Chapter III → Subchapter C → Part 433
People transport:
Title 14 → Chapter III → Subchapter C → Part 460

 

[N5329K]

Trans-oceanic planes are certified with only two engine. Single redundancy. Flammability for space system seems like it would be lower than domestic. Air quality systems are built in. Engine failure containment is already covered. Planes are already fly by wire. Are you thinking extra control actuator redundancy or manual landing leg actuation?
ETOPS (Extended-range Twin-engine Operational Performance Standards) rules permit twin engine jet aircraft to fly routes which, at some point, are more than 60 minutes flying time away from the nearest airport suitable for emergency landing. To become ETOPS certified, manufacturers jump through an impressive number of hoops, most of them dealing with mean time between failure for flight-critical components. Engines especially.
Putting a multi-engine rocket through those hoops would make certifying an airliner seem like child's play. It's one thing to approve the launch of cargo. The engines fire, they stop, they fire again, a couple of times. If the vehicle is recovered, they go through some process of examination and rehabilitation before flying again. If you are having a Really Bad Day, only the fish care (not true for Russian or Chinese launches).
Even developing real numbers for MTBF on rocket components would be a major, major deal. Operationally, you'd have to demonstrate the ability to launch for your intended destination, and then have sufficient cross-track energy to make it to an approved alternate. And be able to land there without a shred of doubt. And then the FAA would need to know how your pilots (if any) are trained, how your mechanics are trained, where your parts were made, how the equipment is kept and maintained, how long employees are allowed to work, on and on and on. I think I mentioned I had a peripheral experience with this in a tiny, tiny airline startup shuttling pax from central New Jersey to Newark, and the paperwork was enough to bury the Brittain Norman Islander(s) doing the actual flying. I mean, totally bury. A paperwork Pyramid of Cheops.
There's a pretty compelling case to be made for flying thousands of people from continent to continent daily. If there were a compelling rationale for rocketing hundreds of people back and forth from continent to continent in a day, well, maybe. But is there really?
Robin

 

[PhantomX]

In addition, the inflight shut down rate cannot be more than 1 per 20,000 hours of flight for ETOPS 60 and 1 per 100,000 hours of flight for ETOPS 180.

Also, that's only related to engine reliability, particularly twin engine airplanes. FAA certifications include everything on the plane, from bracket and bolts, to structures, to systems, and etc. Everything on the airplane has to be certified for strength, durability, crash, and etc. It's going to be many orders harder to certify EP2P compared to Mars version.

 

[mongo]

In addition, the inflight shut down rate cannot be more than 1 per 20,000 hours of flight for ETOPS 60 and 1 per 100,000 hours of flight for ETOPS 180.

Also, that's only related to engine reliability, particularly twin engine airplanes. FAA certifications include everything on the plane, from bracket and bolts, to structures, to systems, and etc. Everything on the airplane has to be certified for strength, durability, crash, and etc. It's going to be many orders harder to certify EP2P compared to Mars version.

And this shows the divergence of sub-orbital travel to planes, the entire flight is sub 60 minutes. Engine on time for first stage is sub 3 minutes, the rest is coasting.

I wonder if the structure of a rocket is easier to inspect and certify than the spar/rib/skin setup of a plane. Less movement/ fatigue issues, and less control surfaces. No landing gear rolling shock test, brake tests, or steering needed either.

 

[PhantomX]

And this shows the divergence of sub-orbital travel to planes, the entire flight is sub 60 minutes. Engine on time for first stage is sub 3 minutes, the rest is coasting.

I wonder if the structure of a rocket is easier to inspect and certify than the spar/rib/skin setup of a plane. Less movement/ fatigue issues, and less control surfaces. No landing gear rolling shock test, brake tests, or steering needed either.

Dynamic loads should be worse on rockets than airplanes. And thermal loads are definitely worst than airplanes. Also, airplane also needs to be certified for different failure events in operation. For example, it needs to be able to continue take off climb if one engine is out after take off speed is reached, or be able to stop if it is below take off speed. It also needs to be able to arrest damage and continue operate until it can return back to an airport. And many more. Also, airplane has to operate when all primary power is lost and show it has enough redundant systems to meet that requirement. Basically a commercial airplane is certified for "what if something is wrong" events. Rockets will need to be the same.

At the minimum the EP2P BFR will have to demonstrate the ability to safely land if it loses its engines at any stage during take off. And also it has to be able to safely operate and land if a structural failure occurs. These are just two of the difficult requirements to satisfy for a EP2P certifications.

 

[RDoc]

If you already have a space/ NASA astronaut approved system, what additional requirement could the FAA add that would be difficult?

NASA requirements are less than 1 in 270 flights result in a crew member death. So that would mean that at every airport with 600 flights per day there would be 2 that resulted in passenger and/or crew fatalities, say 700 per year per airport. I think that there would be some serious issues with that.

 

[dhanson865]

I just watched Gwynne's recent TED talk posted by Grendal. I wished the interviewer had pressed her for more details on the BFR/BFS. I realize this presentation was probably given to a general audience and she's also obligated to protect proprietary information. There are still many of us hungry for more meat and potatoes. We can all relate to the Wow factor of flying to Shanghai and back home the same day to make dinner. I'd welcome more discussion of the challenges, especially those related to in-flight.

Some aspects of the BFS might make it easier to operate in Space and on other worlds vs. making those proposed 30 minute earth hops. The moon and Mars don't present the same weather factors we have here on earth. Air mass thunderstorms can easily develop in less than 30 minutes. As was previously pointed out, alternate landing sites plus required fuel reserves will be mandated by the FAA. There's no doubt that the BFS will have to be capable of a low altitude go-around. This scenario will also likely have to be successfully demonstrated in an engine out configuration. Not routine, but a training exercise practiced in aircraft sims everyday.

I think you have an unrealistic expectation there that is based on not understanding the flight path and it's benefits.

If BFS goes Low Earth Orbit on every flight there is no significant penalty other than time to redirect to an alternate landing site if you make the decision from orbit. The deoribit time is short on the order of a couple of minutes no where near the 30 minute thunderstorm time you mentioned. If there is enough oxygen for the passengers you could wait out a storm at no cost of fuel by just orbiting the earth completely and landing on the next pass.

There is no reason to be doing in atmosphere maneuvering that isn't planned and modeled before the flight starts. Any alternate landing sites will be mapped out with orbit changes required and you will declare your landing spot and commit to it once you fire a deorbit burn. There won't be any last second fly arounds like a jumbo jet does. It'll either land or it won't. If something happens last second that makes a landing unsafe the entire fleet would be grounded for months until an investigation is completed.

I'd say the normal landing uses only 1 engine on a routine basis and the 2nd sea level engine is for redundancy in case of a failure. Either way I don't expect a fly around just because they only have 1 engine burning. It's going to be more graceful than a falling rock but not enough that it can fly around doing low altitude maneuvers.

The 2 engine out scenario would probably be to deploy parachutes and be picked up at sea, and if it ever happened to a passenger it'd again be something that grounds the entire fleet for months until an investigation finishes.

 

[dhanson865]

Trans-oceanic planes are certified with only two engine. Single redundancy. Flammability for space system seems like it would be lower than domestic. Air quality systems are built in. Engine failure containment is already covered. Planes are already fly by wire. Are you thinking extra control actuator redundancy or manual landing leg actuation?
ETOPS (Extended-range Twin-engine Operational Performance Standards) rules permit twin engine jet aircraft to fly routes which, at some point, are more than 60 minutes flying time away from the nearest airport suitable for emergency landing. To become ETOPS certified, manufacturers jump through an impressive number of hoops, most of them dealing with mean time between failure for flight-critical components. Engines especially.
Putting a multi-engine rocket through those hoops would make certifying an airliner seem like child's play. It's one thing to approve the launch of cargo. The engines fire, they stop, they fire again, a couple of times.

Do you not realize that SpaceX is starting and stopping and restarting engines multiple times every Falcon 9 flight? Both Stage 1 and Stage 2 engines have been lit and relit multiple times per mission and do so on a regular basis.

It's de rigueur for rockets. They don't run the engines 8 hours non stop, they burn for seconds or minutes, turn them off and wait, then turn them back on later. All the time, every time.

Not only do they do that in the air and in space but they also start and stop and start again on the ground before every flight. They call it a Static Fire Test and they do them every time anything and I mean anything changes for the spaceship and/or the engines. If they don't like the results they fix something and delay the flight until they like the static fire results. And the less perfect the results the more and more and more they'll test them.

You really don't know SpaceX if you think engine tests would bother them. If you told them that the engine would have to start and stop to the rhythm of Beethoven's 5th Symphony they'd rig it up and have it running next week and then post the video on twitter and youtube.

 

[Nikxice]

I think you have an unrealistic expectation there that is based on not understanding the flight path and it's benefits. If BFS goes Low Earth Orbit on every flight there is no significant penalty other than time to redirect to an alternate landing site if you make the decision from orbit.

Look to post # 26 where I addressed this issue and noted the benefits.

There won't be any last second fly arounds like a jumbo jet does. It'll either land or it won't. If something happens last second that makes a landing unsafe the entire fleet would be grounded for months until an investigation is completed.

Months would be years or possibly never. It's not planned to be a Space tourist vehicle operating over a remote fixed site. The likelihood of an airspace violation occurring during a BFS approach isn't a matter of if it happens, but when. SpaceX will have to satisfy regulatory agencies and guarantee that revenue passengers have survival options beyond "It'll either land or it won't".

 

[PhantomX]

It's not the number of time you can start or stop the engine, the certification is about the number of times unexpected shutdown happens. Jet engines cycles through thousands of cycles throughout it's life, but that is not the same as reliability of operation.

 

[PhantomX]

I think you have an unrealistic expectation there that is based on not understanding the flight path and it's benefits.

If BFS goes Low Earth Orbit on every flight there is no significant penalty other than time to redirect to an alternate landing site if you make the decision from orbit. The deoribit time is short on the order of a couple of minutes no where near the 30 minute thunderstorm time you mentioned. If there is enough oxygen for the passengers you could wait out a storm at no cost of fuel by just orbiting the earth completely and landing on the next pass.

There is no reason to be doing in atmosphere maneuvering that isn't planned and modeled before the flight starts. Any alternate landing sites will be mapped out with orbit changes required and you will declare your landing spot and commit to it once you fire a deorbit burn. There won't be any last second fly arounds like a jumbo jet does. It'll either land or it won't. If something happens last second that makes a landing unsafe the entire fleet would be grounded for months until an investigation is completed.

The 2 engine out scenario would probably be to deploy parachutes and be picked up at sea, and if it ever happened to a passenger it'd again be something that grounds the entire fleet for months until an investigation finishes.

This approach will be very difficult to get certified unless all certification agencies are willing to take a giant departure from their current mindset. Certification is all about risk mitigations and contingencies, so trying to convince certification bodies that the operation has known risks it can't mitigate will likely be a no go from start.

 

[mongo]

NASA requirements are less than 1 in 270 flights result in a crew member death. So that would mean that at every airport with 600 flights per day there would be 2 that resulted in passenger and/or crew fatalities, say 700 per year per airport. I think that there would be some serious issues with that.

NASA is talking about full orbital travel: reentry from orbital speeds, sustained life boat mode, and abort modes. Only the last is really relevent to Earth hops. I'm sure SpaceX is designing for better than 1:270 loss rates.

If BFS goes Low Earth Orbit on every flight there is no significant penalty other than time to redirect to an alternate landing site if you make the decision from orbit. The deoribit time is short on the order of a couple of minutes no where near the 30 minute thunderstorm time you mentioned. If there is enough oxygen for the passengers you could wait out a storm at no cost of fuel by just orbiting the earth completely and landing on the next pass.

I don't think BFS goes orbital. That would require a 90 minute cycle time in case of blocked landing site (at which point you are 20+ degrees of longitude from original target), the burn off of all the excessive speed, and the launch angles would not be favorable.

The likelihood of an airspace violation occurring during a BFS approach isn't a matter of if it happens, but when. SpaceX will have to satisfy regulatory agencies and guarantee that revenue passengers have survival options beyond "It'll either land or it won't".

What precipitating causes to you foresee causing this airspace violation event? Total control system failure, loss of too many engines? (I'm thinking BFS for earth is all sea level versions, so at least 6).
The ship will land... If you peruse the FAA rules regarding space tourists, the provider has to tell them the current failure rates of the fleet (and industry I think) along with the "you may die" clause.

It's not the number of time you can start or stop the engine, the certification is about the number of times unexpected shutdown happens. Jet engines cycles through thousands of cycles throughout it's life, but that is not the same as reliability of operation.

So far, I am aware of 1 engine (older version) with power loss out of 50*10 engines. (BFR/BFS engines are not TEA/TEB based, so no need to worry about that). Consider the level of testing that goes into a second stage engine. Zero redundancy on most/ all systems, and 50/50 so far, including the dual starts for orbital adjustment and the cold soak test.

This approach will be very difficult to get certified unless all certification agencies are willing to take a giant departure from their current mindset. Certification is all about risk mitigations and contingencies, so trying to convince certification bodies that the operation has known risks it can't mitigate will likely be a no go from start.

Known non-mitigatable failure modes are not rare. In those cases, they focus on the occurrence number. Flight on the Hudson for instance, every jet engine has a bird ingestion limit.

 

[N5329K]

Do you not realize that SpaceX is starting and stopping and restarting engines multiple times every Falcon 9 flight? Both Stage 1 and Stage 2 engines have been lit and relit multiple times per mission and do so on a regular basis.

It's de rigueur for rockets. They don't run the engines 8 hours non stop, they burn for seconds or minutes, turn them off and wait, then turn them back on later. All the time, every time.

Not only do they do that in the air and in space but they also start and stop and start again on the ground before every flight. They call it a Static Fire Test and they do them every time anything and I mean anything changes for the spaceship and/or the engines. If they don't like the results they fix something and delay the flight until they like the static fire results. And the less perfect the results the more and more and more they'll test them.

You really don't know SpaceX if you think engine tests would bother them. If you told them that the engine would have to start and stop to the rhythm of Beethoven's 5th Symphony they'd rig it up and have it running next week and then post the video on twitter and youtube.

Oh, I definitely realize that F9 engines are cycled. What I have doubts about is that F9 engines (or any rocket engines I'm at all familiar with) are robust enough to serve the P2P mission ( multiple trips daily without inspection or overhaul), and I also doubt there's a ready market willing to pay a ticket for what this will end up costing. I have no doubts at all about what the company will face regulations-wise, though.
Robin

 

[dhanson865]

I don't think BFS goes orbital. That would require a 90 minute cycle time in case of blocked landing site (at which point you are 20+ degrees of longitude from original target), the burn off of all the excessive speed, and the launch angles would not be favorable.

at about 1:01 into the video it says Max speed 27,000 km/h (7.5 m/s), at what altitude do you expect the BFS to be when it's doing 27,000 km/h?

Orbit of a satellite Calculator and CalcTool: Earth orbit calculator says that would be about 706 km above earths surface if circularized.

That's well above the thermosphere, and Wikipedia lists low earth orbit as being in the range of altitudes from 160 to 2,000 km.

I'm expecting from the video that BFS has the option to circularize within that 160 to 700 km altitude range and then do a deorbit burn when needed.

Maybe the normal operation is to get the apophesis up to LEO levels and still not be "in orbit" so they save the fuel of circularizing and deorbiting.

Either way they are going well into LEO altitudes on those flights.

 

[RDoc]

If you already have a space/ NASA astronaut approved system, what additional requirement could the FAA add that would be difficult?

Your original statement I was responding to. FAA requirement are far harder than NASA requirements.

NASA is talking about full orbital travel: reentry from orbital speeds, sustained life boat mode, and abort modes. Only the last is really relevent to Earth hops. I'm sure SpaceX is designing for better than 1:270 loss rates.

Actually, all of those cases exist in the EP2P scenarios as well. There would be very little difference between an orbital launch and an EP2P launch in hardware or mission profile apart from the length of exposure to space junk. Launch and landing are obviously the times of maximum risk, so the calculations would be very similar.

Perhaps SpaceX would design for 10 times the reliability NASA required. I can't imagine that being remotely acceptable to the FAA. In any case, unless SpaceX gets the FAA on board very early in the BFR/BFS design process, they won't get a certificate and won't be able to fly passengers anytime soon.

 

[mongo]

at about 1:01 into the video it says Max speed 27,000 km/h (7.5 m/s), at what altitude do you expect the BFS to be when it's doing 27,000 km/h?

Orbit of a satellite Calculator and CalcTool: Earth orbit calculator says that would be about 706 km above earths surface if circularized.

That's well above the thermosphere, and Wikipedia lists low earth orbit as being in the range of altitudes from 160 to 2,000 km.

I'm expecting from the video that BFS has the option to circularize within that 160 to 700 km altitude range and then do a deorbit burn when needed.

Maybe the normal operation is to get the apophesis up to LEO levels and still not be "in orbit" so they save the fuel of circularizing and deorbiting.

Either way they are going well into LEO altitudes on those flights.

I could indeed be wrong.
However, I think deriving an altitude based on that video and a circular orbit may not be correct. To create a circular orbit requires an additional burn at apogee to raise perigee. For a point to point flight, the rocket never gets there (apogee). The video shows arbitrary launch directions, so the furthest the trip would normally go is 1/2 a circumference. Even a burn at 1/4 rotation would not make sense. Either of those options to adjust the orbit would mean it had already aborted the initial landing.

Going to a 706km altitude would also require much more energy than needed. Outer space starts at ~100km, lower range of satellites in LEO is 300 km due to drag, but that is a long term consideration. To orbit at 700 km would require seven times the net energy (some multiple of that for the fuel stack up) of a 100 km rise or double a low LEO. No reason to have that much height, even if it is the peak of a parabolic trajectory. For THAICOM-8, Falcon 9 hit 2.7 km/sec at ~350 seconds into flight at an altitude of 160km.
Plot here.

The BFS has to dump all it's energy eventually, so there is no issue with losing some speed to drag during the outer coast phase. I'm thinking BFS is never more than 80km up, possibly much less. It will depend on the velocity/altitude/drag/energy optimization. I may need to make a simulation this weekend...

 

[mongo]

n any case, unless SpaceX gets the FAA on board very early in the BFR/BFS design process, they won't get a certificate and won't be able to fly passengers anytime soon.

Check out the FAA space tourist links I posted above, there is no certification for space trips (currently).

An operator must inform each space flight participant that the United States Government has not certified the launch vehicle and any reentry vehicle as safe for carrying crew or space flight participants.

 

[RDoc]

Check out the FAA space tourist links I posted above, there is no certification for space trips (currently).

Sure if the plan is tourist flights, however, that's not what's being discussed. If SpaceX is going to do anything like a scheduled route system I'd be surprised if they got away with calling it space tourism.

Also, among other things, I'm very doubtful that most peoples' insurance would be in force without an explicit rider, or that companies would allow corporate travel. Without certification, EP2P would certainly be classified as a hazardous activity to say the least.

 

[mongo]

Sure if the plan is tourist flights, however, that's not what's being discussed. If SpaceX is going to do anything like a scheduled route system I'd be surprised if they got away with calling it space tourism.

Also, among other things, I'm very doubtful that most peoples' insurance would be in force without an explicit rider, or that companies would allow corporate travel. Without certification, EP2P would certainly be classified as a hazardous activity to say the least.

Sure, regulations will change as things develop. Currently though, it fall under Reusable Launch Vehicle with Space Flight participant. Many forms of tourism are scheduled, so that would not seem to be an issue.

Admittedly with low number of data points (seven tourists), space tourism is currently safer than air travel. The entire history of space travel has had 18 in flight fatalities out of 536 people in space (including sub-orbital). Total fatality events was 4 out of 319 launches, and in each of these the root cause was identified and mitigated in future launches.

 

[e-FTW]

It will depend on the velocity/altitude/drag/energy optimization. I may need to make a simulation this weekend...

Does KSP have a BFR/BFS?