NASA says it will build quiet supersonic passenger jet

Quote: Pacomartin

Virgin Galactic is predicting that sub-orbital flights linking two distant places in two hours will be on sale in four years (approx $250K per person). Even the most sybaritic subsonic flight won't cost anywhere near $250K.

Not a bad notion, but that's not really what Spaceship 2 was designed for.

Also the destinations will be limited to places where Virgin can base the White Knight ][ mother ship and the multitude of specialized equipment and know-how to service both craft. Refueling a hybrid rocket cannot be done with a fuel truck and Jet A.

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But, I wonder if these private suites will vanish even if the price of sub-orbital comes down to something resembling first class prices.

The Suborbital market will be limited by those unable to take the wild ride. Perhaps an integrated design, sans mother ship, with a more gradual acceleration and lower g factor might work. but in rocketry gradual acceleration=inefficient acceleration. Still, the price of nitrox (or lox) and solid rocket fuel cannot possibly be as volatile as oil.

Quote: Nareed

Also the destinations will be limited to places where Virgin can base the White Knight ][ mother ship and the multitude of specialized equipment and know-how to service both craft. Refueling a hybrid rocket cannot be done with a fuel truck and Jet A.

New York City to Hong Kong is the busiest route over 8000 miles with 5 nonstop planes per day and 1 with a layover in Vancouver. One plane is flown by United, and the other 5 by Cathay Pacific. This service only began in 2001, so you can figure they add a new plane every few years.

I am not sure what is the busiest over 6K miles, but I would bet London Heathrow to Singapore at 6,765 mi is a good candidate.

The 10 busiest air routes are all domestic (or HKG to TPE), so I don't know what would be the busiest over 3K miles, but I would bet on Dubai to London.

Quote: Nareed

The Suborbital market will be limited by those unable to take the wild ride.

I assume you mean "subsonic".

Quote: Pacomartin

Interjet has a very high vacancy rate.

That's one more reason to like it. Although I've been on several packed flights.

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Volaris claims these are the average number of passengers per flight.
137 Volaris
122 VivaAerobus
104 Interjet

I know Interjet gets in only 150 seats per A320. I think Volaris goes as high as 180, and no idea what Viva does. So I wonder what the numbers translate to as a percentage of available seats.

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So if the seats:attendants are 37.5:1, the passengers:attendants is usually a lot lower.

Depends largely on the route. TLC LAS is sparsely populated. MEX to Ciudad del Carmen is consistently packed.

But still, beyond the snack and drink service, there's little for the FAs to do aside from their regular duties for takeoff and landing.

Quote: Pacomartin

I assume you mean "subsonic".

There's nothing wild about subsonic.

The current Virgin Galactic configuration involves a regular takeoff. This is followed by the separation of Spaceship 2 from the WK mother ship, which involves an unpowered drop of several hundred meters and, unadvertised, zero g. Net the hybrid rocket is turned on and the nose points sharply upwards. not straight up, but it will feel that way. I don't know what the acceleration is, but surely beyond 2.5 g. Next you get a few minutes in space with, advertised, zero g. I think this is when the seatbelt sign is turned off. Now you enter the atmosphere and suffer through a few g's of deceleration. Finally you glide at supersonic speeds while steadily going down, unpowered, and slowing down.

On the way to the landing, you may muse that the unpowered craft cannot do a go around and has to land on its first attempt, whether the runway is clear or not.

Quote: Nareed

The Suborbital market will be limited by those unable to take the wild ride.

The Suborbital market will be limited by those able to take a wild ride.
The Subsonic market will be limited to those unable to take the wild ride.


Concorde takes off at 220 knots, compared with 165 knots for most subsonic aircraft. The extra power required for take off is produced by its four engines giving more than 38,000 lbs of thrust, that’s 0 - 225mph in just 30 seconds. Concorde also has to reach its take off speed quicker than subsonic aircraft, so uses higher acceleration, which is why passengers feel a slight ‘push back’ in their seats.

The extra acceleration for a normal commercial aircraft is about .05g. The extra acceleration in the Concorde was about .33g for fully loaded up to .90g for an empty Concorde (should you be able to afford the charter). The space shuttle was limited to 3g for passenger comfort. The human centrifuge goes up to 4.5 g, but only at the feet.

Quote: Pacomartin

The Suborbital market will be limited by those able to take a wild ride.

No. those able to take the wild ride won't limit the market.

What you mean is "The suborbital market will be limited TO those able to take the wild ride."

Quote: Nareed

What you mean is "The suborbital market will be limited TO those able to take the wild ride."

A suborbital flight is any flight outside the Earth's atmosphere with a maximum flight speed below the orbital velocity. Traditionally, the Kármán line, at 100 km, or 1.57% of Earth's radius, is used as the border between the atmosphere and outer space.

White Knight Two has a service ceiling of 18-21 km , but it can only take a 17,000 kg payload to 15km. AFAIK they have not been higher than 14 km.
On October 31, 2014, VSS Enterprise, broke apart at less than 16 km.

In dry air at 20 °C , the speed of sound is 343.2 metres per second. Usually the terms hypersonic is applied to speeds above Mach 5. So SpaceShipOne and SpaceShipTwo are well into the hypersonic speeds.

SpaceShipTwo has a peak speed of 4,000 km/h and a service ceiling of 110 km.
SpaceShipOne had a peak speed of 3,518 km/h and a service ceiling of 112 km

As I understand it, there is some design iterations on SpaceShipTwo, but they calculated a maximum acceleration of 4g with SpaceShipOne (I don't know what they actually experienced).

There is some scuttlebutt that SpaceShipTwo in it's desire to be roomier and limit itself to more comfortable accelerations, may not reach 100 km.

So Suborbital flight certainly implies supersonic speeds, and probably hypersonic ones. It will also involve some nasty accelerations. It will be uncomfortable (i.e. a wild ride) and will probably involve more vomiting than a normal subsonic flight even in bad weather.

"The suborbital market will be limited TO those passengers able to take the wild ride."

Thrill seekers and the truly desperate to get to their destination will tolerate paying huge amounts of money and risk getting sick. But the normal wealthy will still pay for a flat bed and 16 hours in a tube.

Quote: Pacomartin

Thrill seekers and the truly desperate to get to their destination will tolerate paying huge amounts of money and risk getting sick. But the normal wealthy will still pay for a flat bed and 16 hours in a tube.

For now.

The Virgin Galactic system was designed for suborbital thrill rides, much like what Spaceship One did. It goes to space just to go to space. It's like making antimatter in the LHC. You can do it, but it's hideously expensive. If you wanted antimatter at a more reasonable cost per picogram, you'd need to design a particle accelerator optimized for the purpose (as yet there's no sue for industrial amounts of antimatter, say in the milligram range).

So, it's good if VG gets to prove origin-destination suborbital flights are a possibility. and it would be great publicity if they can get a few passengers from, say, LA to Sydney in under two hours.

But for serious suborbital commercial service, we'll have to wait for developments in the aerospace industry.

Quote: Nareed

But for serious suborbital commercial service, we'll have to wait for developments in the aerospace industry.

Well you can't get around the laws of physics. That means you are going to have some serious accelerations which are inherently uncomfortable.

Structural improvements have allowed us to increase the air pressure in a plane to make it more comfortable. Many new commercial planes are the equivalent of 6000' elevation instead of 8000' or 10,000' for military planes. You can design better chairs to take some of the acceleration, but you can't eliminate the force.

Quote: Pacomartin

Well you can't get around the laws of physics. That means you are going to have some serious accelerations which are inherently uncomfortable.

Yes, but it's possible to have lower accelerations at the cost of increasing flight time for forty to sixty minutes.

NASA toyed with a space plane design with multiple engines, or variable engines (however that would work), which would have accelerated, sedately, to hypersonic speeds while in the atmosphere, then it would fire rockets at high g. Eventually that's what a successful suborbital plane for commercial travel should be like.

Of course it would be hideously expensive. We still don't know how to make a supersonic passenger jet which won't cost more than first class per ticket.

I want to say the cost would drop as the technology develops further, as has happened with everything from cars to computers to regular air travel, but the massive amounts of fuel required and the unfavorable fuel to payload ratio argue against significant drops in cost. Consider, there are plenty of low cost and ultra-low cost carriers all over the world, plying short and medium haul routes. But low cost long haul jet travel has proved most elusive.