Virgin One has finally reached orbit with their air launch to orbit system, but what
does that mean?
And why don’t we do this for all rockets?
Let’s talk about that today.
Hey guys Tory here from Overlook Horizon on Sunday January 17th, Virgin Orbit successfully
launched their Launcher One platform into to low earth orbit.
This was only their second demonstration flight and it carried a total of 10 small CubeSats into orbit
and as far as I can tell, they nailed it.
Now this is obviously better than the first time around, which failed shortly after launch
when one of the liquid oxygen lines actually broke and the engine was no longer receiving
oxygen and it was ultimately terminated, although they’ve never shown us video of that, I’ve
heard it was pretty fiery descent.
Now Virgin Orbit’s Launcher One platform is pretty unique, because it’s the first
air launch orbital rocket that is liquid fueled.
Now we’ve had an air launch rocket sent into orbit before, that’s the Northrop Grumman
Pegasus rocket, but that’s a solid fueled rocket which is a little different than Virgin
Orbit’s liquid fueled rocket which uses RP-1 kerosene and liquid oxygen just like
say the SpaceX’s Falcon 9.
Now an air launch system is essentially a rocket that's mounted to the underside of
a wing on a giant airplane.
It takes off from a runway, the plane will perform a number of checkouts before pointing
the rocket in the right direction and then dropping it.
At that point, the engines would ignite and it would be on its way orbit.
The main advantage to an air launch rocket system is obviously starting your rocket at
a higher altitude, but a lot of people think that this is because it has a head start and
it's closer to space so you’re almost there, right?
Well not exactly.
Remember to get to space you go up, but to stay in space you go sideways, very fast!
and it's this sideways movement that's actually the bigger task.
The big advantage really is that you start your rocket engine above the dense part of
the atmosphere which is at lower altitudes.
The thicker atmosphere means the rocket has to work harder against things like atmospheric drag.
Also, you can get better performance out of your rocket by having an engine nozzle that
doesn’t have to worry about sea level atmosphere.
I’m sure you’ve seen this on say like the SpaceX’s new Raptor engines where the sea level engine
nozzle is much smaller than the engine nozzle that’s designed for stages that only operate
in the vacuum of space.
Now, what the nozzle of a rocket engine is trying to do is to cram the exhaust gas through
a throat to create high pressure and then allow it to expand quickly back to low pressure
to create supersonic high speed exhaust.
The thing is you want the pressure of your exhaust at the end of the nozzle to match
the ambient air pressure for the best efficiency and that’s why sea level engines nozzles
are smaller to match the ambient higher pressure there at sea level, now compare that to the
vacuum of space where you want the exhaust to expand much further since there’s virtually
no pressure in space.
If your engine bell is sized too small for the ambient environment, the exhaust will
expand further outside your nozzle and you'll lose efficiency.
If your nozzle is too big, the atmosphere will pinch your exhaust and with enough pressure
you can potentially get flow separation from the walls of the nozzle which can cause the
exhaust to flop around inside the nozzle and potentially damage the engine.
So engine manufacturers need to find a sweet spot, particularly when it comes to sea level engines.
The tough thing with sea level engines is that they don’t operate exclusively at sea
level you inherently lose efficiency as you change altitude.
We see this pretty often in the Falcon 9 where the exhaust plume expands very wide
as it gets to the higher altitudes which is not efficient.
An air launch rocket can have a nozzle that is designed just for the low pressure or vacuum
environments and not have to worry about sea level air pressure or density.
So why doesn’t everyone do this?
Well, the problem is that this gets complex.
Now you have to add an airplane to your fleet which has its own costs and maintenance and
things like that and the savings that you get after all that is factored in, is...
not much.
There’s also a scalability problem, because this doesn’t scale to larger rockets.
Imagine the size of the plane you’d need for a bigger rocket.
Virgin Orbit’s platform is geared towards smaller CubeSats.
It’s not much of a competitor to something like the Falcon 9 or the Delta IV Heavy, but
it’s more directly in line with something like Rocket Lab’s Electron rocket, but in
further evidence of the cost problem, Virgin Orbit is performing these air launches at around
12 to 13 million dollars per launch, while Rocket Lab is launching a more traditional
rocket with the same capacity for only about 7.5 million dollars per launch.
Now I do have to hand to Virgin Orbit, getting that down to 12 to 13 million dollars is a
huge achievement especially when you consider that the Pegasus rocket is about $40 million
per launch so Virgin Orbit will be a great competitor for Rocket Lab and I’m sure there
will be customers at that price.
So let me know what you guys.
Do you think Virgin Orbit will start to become a major player in the small satellite industry?
I don't know, I’m excited to find out.
As always be sure to click the like button, consider subscribing and I'll see you on the next video.
Goodbye.
[noises]
...consider that the text doesn't scroll and so I have no idea what I'm supposed to say next.