Imagining the future spaceport infrastructure

[santiherranz]

Just want to share here my recurring dream.

Launch track assistant and landing tower assistant in the same place.

How much fuel would be saved if the rocket was launched at 500 km/h with an electric acceleration rail?

Maybe 20% savings?

[Jim]

Just want to share here my recurring dream.

Launch track assistant and landing tower assistant in the same place.

How much fuel would be saved if the rocket was launched at 500 km/h with an electric acceleration rail?

Maybe 20% savings?

Not viable.  Limits the launch to only one azimuth.  Also puts additional loads into the structure making the vehicle heavier.  500km/hr at launch will mean Max q loads will be higher since the vehicle is going faster in the denser part of the atmosphere .

[laszlo]

Just want to share here my recurring dream.

Launch track assistant and landing tower assistant in the same place.

How much fuel would be saved if the rocket was launched at 500 km/h with an electric acceleration rail?

Maybe 20% savings?

Not viable.  Limits the launch to only one azimuth.  Also puts additional loads into the structure making the vehicle heavier.  500km/hr at launch will mean Max q loads will be higher since the vehicle is going faster in the denser part of the atmosphere .

The rocket can use engines/aerodynamics to change the azimuth of its ground track, albeit at a fuel cost that may make it not worth it. No argument with the other points.

[santiherranz]

Thanks for the replies!
Perhaps it would work with an initial push stage 0, aerodynamic fins to orient the vehicle in the desired direction and reinforce to reach higher altitude before light the stage 1 booster. Also this stage 0 could return to the landing tower and be reused.

[rakaydos]

500 KPH is only 139 m/s. Orbital velocity is over 7,000 m/s.

The gains are minimal, even without looking at the penalties.

[DanClemmensen]

Just want to share here my recurring dream.

Launch track assistant and landing tower assistant in the same place.

How much fuel would be saved if the rocket was launched at 500 km/h with an electric acceleration rail?

Maybe 20% savings?

You should (re)read some excellent old science fiction, such as Heinlein's "The Moon is a Harsh Mistress", where electromagnetic rail launchers are discussed a whole lot. The big problem with a serious ground launch system is air resistance, The classic SciFi solution is to put the egress at the top of the highest mountain you can find. you can also put your track in a long tunnel (hello Boring Company?). Make the tunnel as long as you want and accelerate along the tunnel at a modest acceleration to get to whatever egress speed you like. The egress end of the tunnel is vertical so there is a nice long bend from horizontal to vertical and no azimuth bias. The problem occurs when the vehicle leaves the tunnel and suddenly hits the atmosphere at your chosen egress speed. Ouch. figure out how to solve the transition from the tunnel to then atmosphere and your dream is realized.

Note that you don't have this problem when launching from the Moon so the only reason to tunnel is to make the transition from horizontal to vertical.

[Twark_Main]

Just want to share here my recurring dream.

Launch track assistant and landing tower assistant in the same place.

How much fuel would be saved if the rocket was launched at 500 km/h with an electric acceleration rail?

Maybe 20% savings?

The savings is roughly 4.2% of the total liftoff mass.

Obviously the fraction of the total cost savings will be smaller than that (because rockets are a mixture of "per pound" and "per unit" costs, and only the "per pound" portion is reduced here), but let's be extremely generous and say that this represents a 4.2% savings on the rocket. In reality I expect the savings would be closer to 1-2%, but no matter.

This means your launcher structure must cost less than 4.2% of your total cost. If the combined capital amortization + operation + ongoing maintenance cost of this huge, complex, unprecedented structure is more than 4.2% of your company's total cost structure (spoiler alert: it will be), it'll be cheaper to simply build your rocket 4.2% bigger and call it a day.

[santiherranz]

WOW, my dream has already another version with a rotary accelerator from company www.spinlaunch.com

WATCH THIS! 

[Robotbeat]

I think launching vertically is better for most of these concepts. Allows launch in any direction.

I don’t think launch assist beyond Mach 3 or so is really helpful. And honestly, about 300m/s is probably near the limit of usefulness.

Around a 500m tall launch assist tower. Accelerate at 10gees or so. Gets you to 300m/s.

Higher than that means a lot of work for little gain. In fact, generally the smaller amount of assist, the higher proportionally the relative efficiency of the assist. Rocket energy efficiency is lowest at low speeds.

You need to have extremely high launch cadence for it to be worth doing, though. Like dozens of launches per day.

[Robotbeat]

 If I have a single-stage rocket with a wet:dry mass ratio (not including payload) of 20:1 and an exhaust velocity of 3.7km/s and a delta v to LEO of 9.67km/s, then I get a ~30% payload increase by getting a 300m/s launch assist.

But that might not be the full story. Gravity losses are highest at low speeds. Engine Isp is lowest at low altitude. On the other hand, higher velocity lower in the atmosphere means more aero losses. High Gee launch assist means heavier structure.

So let’s stick with that 30%.

But that’s kind of an over-estimate as using a single stage is kind of worst case for a rocket. The payload benefit is much smaller for multistage rocket.

[dchenevert]

Just want to share here my recurring dream.

Launch track assistant and landing tower assistant in the same place.

How much fuel would be saved if the rocket was launched at 500 km/h with an electric acceleration rail?

Maybe 20% savings?

just for fun

[Ludus]

This is about the same math as for air launch like Virgin Orbit or what Stratolaunch intended. A jet carrier can provide 800 kph+.

As answers already stated, this adds very little to orbital velocity needed and saves very little propellant for all the additional expense.

The main selling point for Virgin Orbit is they can launch into any orbit from airports all over the world and have the flexibility to avoid weather than can interfere at fixed launch sites. That wouldn’t apply to the suggested systems.

[Asteroza]

This is about the same math as for air launch like Virgin Orbit or what Stratolaunch intended. A jet carrier can provide 800 kph+.

As answers already stated, this adds very little to orbital velocity needed and saves very little propellant for all the additional expense.

The main selling point for Virgin Orbit is they can launch into any orbit from airports all over the world and have the flexibility to avoid weather than can interfere at fixed launch sites. That wouldn’t apply to the suggested systems.

I would have thought any artillery style system would be by definition an all weather launch system. Upper level wind shear or lightning should be a non-issue for such a small reinforced object flying at such extremes?

[Robotbeat]

This is about the same math as for air launch like Virgin Orbit or what Stratolaunch intended. A jet carrier can provide 800 kph+.

As answers already stated, this adds very little to orbital velocity needed and saves very little propellant for all the additional expense.

The main selling point for Virgin Orbit is they can launch into any orbit from airports all over the world and have the flexibility to avoid weather than can interfere at fixed launch sites. That wouldn’t apply to the suggested systems.

I would have thought any artillery style system would be by definition an all weather launch system. Upper level wind shear or lightning should be a non-issue for such a small reinforced object flying at such extremes?

That is true, but I kind of suspect there might be a risk of triggered lighting due to hypersonic drag generating plasma. Less than a rocket, but not necessarily zero.

But overall, that's a good point.

Of course, you could also harden a conventional rocket like that, although it'd be expensive.

[Asteroza]

This is about the same math as for air launch like Virgin Orbit or what Stratolaunch intended. A jet carrier can provide 800 kph+.

As answers already stated, this adds very little to orbital velocity needed and saves very little propellant for all the additional expense.

The main selling point for Virgin Orbit is they can launch into any orbit from airports all over the world and have the flexibility to avoid weather than can interfere at fixed launch sites. That wouldn’t apply to the suggested systems.

I would have thought any artillery style system would be by definition an all weather launch system. Upper level wind shear or lightning should be a non-issue for such a small reinforced object flying at such extremes?

That is true, but I kind of suspect there might be a risk of triggered lighting due to hypersonic drag generating plasma. Less than a rocket, but not necessarily zero.

But overall, that's a good point.

Of course, you could also harden a conventional rocket like that, although it'd be expensive.

If people are that worried, why not fire a laser along the flight path to trigger lightning to a lightning rod you control though? For that matter, why aren't current launchpads equipped with laser lightning trigger systems to redirect lightning though? Not reliable enough to trigger a strike, or the final redirection to a rod isn't reliable enough?

[Jim]

This is about the same math as for air launch like Virgin Orbit or what Stratolaunch intended. A jet carrier can provide 800 kph+.

As answers already stated, this adds very little to orbital velocity needed and saves very little propellant for all the additional expense.

The main selling point for Virgin Orbit is they can launch into any orbit from airports all over the world and have the flexibility to avoid weather than can interfere at fixed launch sites. That wouldn’t apply to the suggested systems.

I would have thought any artillery style system would be by definition an all weather launch system. Upper level wind shear or lightning should be a non-issue for such a small reinforced object flying at such extremes?

That is true, but I kind of suspect there might be a risk of triggered lighting due to hypersonic drag generating plasma. Less than a rocket, but not necessarily zero.

But overall, that's a good point.

Of course, you could also harden a conventional rocket like that, although it'd be expensive.

If people are that worried, why not fire a laser along the flight path to trigger lightning to a lightning rod you control though? For that matter, why aren't current launchpads equipped with laser lightning trigger systems to redirect lightning though? Not reliable enough to trigger a strike, or the final redirection to a rod isn't reliable enough?

Because a near strike is just as bad

[Vahe231991]

Given that the second commercial SpaceShipTwo flight is scheduled for this month, expect Spaceport America to gear up for more forthcoming passenger flights of SpaceShipTwo and the yet-to-be-flown SpaceShipThree by adding another runway and creating a new radar station to allow contact with passengers and crew for SpaceShipTwo and SpaceShipThree. China could create an airport-like spaceport with a very long runway in Xinjiang for a horizontal take-off and landing passenger spaceplane powered by a TBCC engine if it decides that a Buran-type reusable launch vehicle carries technological risk.

[darkenfast]

Spaceport America has no need for, nor can they afford, another runway. Why would they need a new radar station to "allow contact" with passengers and crew? The last sentence makes no sense.

Did a human write this?

[Vahe231991]

Spaceport America has no need for, nor can they afford, another runway. Why would they need a new radar station to "allow contact" with passengers and crew? The last sentence makes no sense.

Did a human write this?

The FAA last week launched a new committee to explore possible regulations with respect to commercial human spaceflight, so a ground-based control center for allowing contact with passengers and crew of SpaceShipTwo could be built at Spaceport America to make sure that nothing is wrong with people aboard SS2 during a future commercial suborbital flight of SS2. I wanted to clarify that for Spaceport America to use radar to track SS2 at altitude is a different thing than radio operators contacting the pilot of SS2 in case SpaceShipTwo runs into a problem during a suborbital flight.

[cohberg]

^/s

ground-based control center ... could be built at Spaceport America

I suppose you could build a ground-based control center ... right next to the other already existing ground-based control center at Spaceport America.
I guess the alternative to a ground-based control center is an airborne control center. Maybe stratolaunch will lease Virgin their 747 back.

creating a new radar station to allow contact with passengers and crew

Yes, I too often use radar over radio to communicate. Ping Ping Ping

allow contact with passengers and crew for SpaceShipTwo and SpaceShipThree

allowing contact with passengers and crew of SpaceShipTwo

I am also a passionate advocate for passenger rights to use the radio on all commercial plane flights at all times.
The pilots and ATC are very happy when I barge into the cockpit and talk over them as the radio channels are unneeded for important communications.
Its great that the FAA has many regulations for ensuring access to radio communication for all passengers on commercial flights

radar to track SS2 at altitude is a different thing than radio operators contacting the pilot of SS2

Is this an attempt to salvage the post or another non sequitur?
I guess a radar return on the hull is comprehensive enough as a communication solution for the FAA to determine that there are no issues across the board.
When they accidentally early feather and need to bail out, it may be too loud to use radio. In that case they can switch to primary radar for tracking individuals under chutes to remain in contact.