Developing the BFS - Phase 1 - StarHopper - THREAD 4

[kevindbaker2863]

Could someone who knows the math do the worst-case scenario calculations based on a full propellant load of the hopper?   something like it lifts off then it suddenly turns and does a max thrust towards the closest public and then blows up so that big chunks of steel fly towards a person that is not expecting it? I remember seeing something like this at the beginning of Boca Chica for what happens if an F9  has a worst-case scenario?      Please?  if its already done here on NSF can you point to it?  I have not found it yet?  Thanks

[Nomadd]

Could someone who knows the math do the worst-case scenario calculations based on a full propellant load of the hopper?   something like it lifts off then it suddenly turns and does a max thrust towards the closest public and then blows up so that big chunks of steel fly towards a person that is not expecting it? I remember seeing something like this at the beginning of Boca Chica for what happens if an F9  has a worst-case scenario?      Please?  if its already done here on NSF can you point to it?  I have not found it yet?  Thanks

More like a wild guess without knowing the dry weight of the hopper. But, no worries. We have the best $50 Home Depot canopy you can get for protection.

[DigitalMan]

I suspect the lack of an updated environmental assessment is going to make it impossible to get any licenses expedited.

[Slothman]

Could someone who knows the math do the worst-case scenario calculations based on a full propellant load of the hopper?   something like it lifts off then it suddenly turns and does a max thrust towards the closest public and then blows up so that big chunks of steel fly towards a person that is not expecting it? I remember seeing something like this at the beginning of Boca Chica for what happens if an F9  has a worst-case scenario?      Please?  if its already done here on NSF can you point to it?  I have not found it yet?  Thanks

The thing is, we don't know how much fuel they're going to load into Hoppy for the 200m test, but I don't think it CAN be full capacity, otherwise it will simply be too heavy to lift off. The question is, is it enough to make raptor burn long enough to get to that distance..

A single Raptor has 2 MN thrust ( 200 tons )

So in order to lift off at all, the total hoppy weight at launch can not exceed 200 tons (at least not by much, if they don't want to burn a hole into the pad until Raptor chugged through enough fuel to make it light enough to lift off).

Hoppy dry weight as far as I heard is 80 tons. So they can add around 120 tons of fuel.

Fuel Ratio: 3.8 units Oxidizer to 1 unit of Methane
3.8x + 1x = 120  | :4.8
x = 25

3.8 * 25 = 95 tons Oxygen
rest: 25 tons Methane

From what I found, raptor uses 565 kg fuel per second. Although I have not found out if this is "fuel" or "fuel mixture". This is important for the next calculation:

25 tons methane / 565 kg per second = around 44 seconds burn time
120 tons total propellants / 565 kg per second = around 3 min 30 seconds burn time. This sounds more reasonable, if they want to go up 200 meters and not rush it.

I'm too stupid to do it myself, but I found this website:
http://www.rocketmime.com/rockets/rckt_eqn.html

Maybe someone can put in the numbers. If not, I'll try to put it in an excel at a later time since I don't have the time now.

[Kabloona]

edit: quote removed

Yes, we're all anxious to see Starhopper hop. But before blaming FAA for foot-dragging, let's take a short trip down memory lane, to the SpaceShipTwo crash in 2015, which rained debris dangerously close to the general public.

The accident investigation resulted in NTSB finding that the FAA had hurried the approval process under pressure and failed to address the possibility of pilot error.

https://www.latimes.com/business/la-fi-faa-virgin-crash-20150801-story.html

There are always at least two sides in the regulatory environment, and it's a struggle between competing interests to find the right balance between excessive caution and recklessness. The FAA is probably still smarting from the SpaceShipTwo incident in which they were shown to have failed to correctly assess the risk to the public.

Starhopper is likely to hop in a few days, and then perhaps the current round of moaning about FAA foot-dragging can take a break until the next time SpaceX needs a permit.

Meanwhile, let's remember that the houses and/or lives that might be saved by FAA due diligence could belong to Nomadd, or one of our other favorite Boca Chica residents. 

[gaballard]

edit: quote removed

The FAA makes the rules. If you want to fly, you “bend over backwards” to follow the rules. That’s how rules and authority structures work. Just because one company of thousands wants to fly sooner doesn’t mean they have the right to demand regulators should start working Saturdays to accommodate them. We love SpaceX, but they’re not the only thing on the FAA’s plate.

[gongora]

Some discussion of the FAA and its approval process it on topic.  Rants about the 737 Max are not even remotely on topic and posts about it will be removed.

[armchairfan]

Could someone who knows the math do the worst-case scenario calculations based on a full propellant load of the hopper?   something like it lifts off then it suddenly turns and does a max thrust towards the closest public and then blows up so that big chunks of steel fly towards a person that is not expecting it?

Since you said worst case ...

I'm guessing that given likely fuel loads, Raptor throttling, and gravity losses associated with an envisioned (slow-ish vs impulse and hoverslam) 150m hop, hopper could easily create a very bad day for our intrepid NSF reporters ... if told to do so by some diabolical SpaceX engineer. 

Mapping out the risk envelope between that extreme and a nominal flight in order to make a reasonable decision takes more time.

[butters]

Short of a whistleblower calling up the FAA and telling them to look into the feather control latches on SS2, the FAA could have taken a whole year to do safety reviews and probably still wouldn't have prevented the accident. The Dragon DM-1 and AMOS-6 anomalies would have been extremely difficult to anticipate. If something goes wrong with Starhopper, it's unlikely to be related to any of the concerns being raised by FAA.

Without straying too far into commercial aviation, suffice it to say that FAA has dramatically more data, industry standards, and hardware familiarity to help them evaluate flight safety criteria. With Starhopper there's only so much they can reasonably do. It's really up to the SpaceX engineers who think about their systems in the shower every morning to imagine what could possibly go wrong. I feel for the FAA engineers who have to sign off on this rocket-propelled water tower, who are probably wringing their hands and complaining to their bosses: "how the heck should I know?"

[Kabloona]

Without straying too far into commercial aviation, suffice it to say that FAA has dramatically more data, industry standards, and hardware familiarity to help them evaluate flight safety criteria. With Starhopper there's only so much they can reasonably do.

Yes. All FAA can reasonably do here is assess total stored energy of propellants, apply quantity-distance limits, and establish a ceiling low enough to minimize the potential for collateral damage.

[ModeHopper]

Short of a whistleblower calling up the FAA and telling them to look into the feather control latches on SS2, the FAA could have taken a whole year to do safety reviews and probably still wouldn't have prevented the accident. The Dragon DM-1 and AMOS-6 anomalies would have been extremely difficult to anticipate. If something goes wrong with Starhopper, it's unlikely to be related to any of the concerns being raised by FAA.

Without straying too far into commercial aviation, suffice it to say that FAA has dramatically more data, industry standards, and hardware familiarity to help them evaluate flight safety criteria. With Starhopper there's only so much they can reasonably do. It's really up to the SpaceX engineers who think about their systems in the shower every morning to imagine what could possibly go wrong. I feel for the FAA engineers who have to sign off on this rocket-propelled water tower, who are probably wringing their hands and complaining to their bosses: "how the heck should I know?"

With this in mind, and looking forward to the SS Mk.1 hop tests, is there any chance that SpaceX are moving JRTI through the Panama canal in order to bring it to Boca Chica? I imagine it would be much easier to get FAA clearance for a hop test performed 50km off shore.

[Kabloona]

Short of a whistleblower calling up the FAA and telling them to look into the feather control latches on SS2, the FAA could have taken a whole year to do safety reviews and probably still wouldn't have prevented the accident. The Dragon DM-1 and AMOS-6 anomalies would have been extremely difficult to anticipate. If something goes wrong with Starhopper, it's unlikely to be related to any of the concerns being raised by FAA.

Without straying too far into commercial aviation, suffice it to say that FAA has dramatically more data, industry standards, and hardware familiarity to help them evaluate flight safety criteria. With Starhopper there's only so much they can reasonably do. It's really up to the SpaceX engineers who think about their systems in the shower every morning to imagine what could possibly go wrong. I feel for the FAA engineers who have to sign off on this rocket-propelled water tower, who are probably wringing their hands and complaining to their bosses: "how the heck should I know?"

With this in mind, and looking forward to the SS Mk.1 hop tests, is there any chance that SpaceX are moving JRTI through the Panama canal in order to bring it to Boca Chica? I imagine it would be much easier to get FAA clearance for a hop test performed 50km off shore.

No, it's been reported by multiple reliable sources that JRtI is going to the Cape.

[Zephyrox]

I believe everyone of us have a story on how some authority that has "failed" us and we're taking it out on FAA now.

Spacex have an insane progress, faster than most of us could have dreamed of. IMHO the biggest threat for SS/SH now isn't technical but rather a serious incident we're they have to take things back a few steps.
Let's all be thankful for additional engineers assessing the risks!

[abaddon]

With this in mind, and looking forward to the SS Mk.1 hop tests, is there any chance that SpaceX are moving JRTI through the Panama canal in order to bring it to Boca Chica? I imagine it would be much easier to get FAA clearance for a hop test performed 50km off shore.

No, it's been reported by multiple reliable sources that JRtI is going to the Cape.

This FAA stuff has been very recent, more recent than the JRtI->Cape reports.  It's possible that JRtI has been diverted to Boca Chica for this purpose.

That all said, I think it's really unlikely.  But I don't think the reports that it was headed for the Cape are necessarily in conflict.

[ModeHopper]

With this in mind, and looking forward to the SS Mk.1 hop tests, is there any chance that SpaceX are moving JRTI through the Panama canal in order to bring it to Boca Chica? I imagine it would be much easier to get FAA clearance for a hop test performed 50km off shore.

No, it's been reported by multiple reliable sources that JRtI is going to the Cape.

This FAA stuff has been very recent, more recent than the JRtI->Cape reports.  It's possible that JRtI has been diverted to Boca Chica for this purpose.

That all said, I think it's really unlikely.  But I don't think the reports that it was headed for the Cape are necessarily in conflict.

Either way, we know that SpaceX are going to acquire a barge for SS/SH launches at some point, perhaps this will simply expedite that process.

[rsdavis9]

With this in mind, and looking forward to the SS Mk.1 hop tests, is there any chance that SpaceX are moving JRTI through the Panama canal in order to bring it to Boca Chica? I imagine it would be much easier to get FAA clearance for a hop test performed 50km off shore.

No, it's been reported by multiple reliable sources that JRtI is going to the Cape.

This FAA stuff has been very recent, more recent than the JRtI->Cape reports.  It's possible that JRtI has been diverted to Boca Chica for this purpose.

That all said, I think it's really unlikely.  But I don't think the reports that it was headed for the Cape are necessarily in conflict.

https://twitter.com/SpaceXFleet/status/1163584759722860545

I have a destination for Just Read the Instructions! The droneship is heading for Morgan City, Louisiana.

It is VERY important to note that this is where JRTI and OCISLY were built in 2015.

[ModeHopper]

With this in mind, and looking forward to the SS Mk.1 hop tests, is there any chance that SpaceX are moving JRTI through the Panama canal in order to bring it to Boca Chica? I imagine it would be much easier to get FAA clearance for a hop test performed 50km off shore.

No, it's been reported by multiple reliable sources that JRtI is going to the Cape.

This FAA stuff has been very recent, more recent than the JRtI->Cape reports.  It's possible that JRtI has been diverted to Boca Chica for this purpose.

That all said, I think it's really unlikely.  But I don't think the reports that it was headed for the Cape are necessarily in conflict.

https://twitter.com/SpaceXFleet/status/1163584759722860545

I have a destination for Just Read the Instructions! The droneship is heading for Morgan City, Louisiana.

It is VERY important to note that this is where JRTI and OCISLY were built in 2015.

Louisiana for modifications and then onwards to Boca Chica afterwards perhaps? 

[capoman]

twitter.com/harrystoltz1/status/1163887863663976449

What will happen to Starhopper after all the tests?  Water tower?  💦

https://twitter.com/elonmusk/status/1163888165901484037

Will be converted to Raptor vertical test stand

Is this a tongue in cheek joke? That's pretty well what it is now, LOL

[Slothman]

twitter.com/harrystoltz1/status/1163887863663976449

What will happen to Starhopper after all the tests?  Water tower?  💦

https://twitter.com/elonmusk/status/1163888165901484037

Will be converted to Raptor vertical test stand

Is this a tongue in cheek joke? That's pretty well what it is now, LOL

They could just tether it permanently and put a fixed gse connection back on it, remove RCS and maybe put it on a flame trench.

I'm not sure if it was a joke. If it wasn't, I don't see the benefit of testing raptors in boca chica, assuming hoppy doesn't travel to McGregor.

On one side, it's a realistic test setup, distances and properties of pipework and tanks match real conditions. It's built like an armored vehicle of war and has proven itself to be resistant to flames.

 On the other hand, if anything goes wrong, which is  to be expected. "This is why we test". They will have destroyed a piece of history, a milestone in starship development, indtead of just a bunch of purpose-built test stand equipment.

I zhink elon said previously that it will be turned into a museum piece or monument or similar.

[AC in NC]

I'm not sure if it was a joke. If it wasn't, I don't see the benefit of testing raptors in boca chica, assuming hoppy doesn't travel to McGregor.

It could be just as simple as that it is the lowest cost "Test Stand #3"