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XS-1 Moves Forward, Stratolaunch Booster Remains Mystery

By Doug Messier
Parabolic Arc
May 4, 2016
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Credit: DARPA

Credit: DARPA

A couple of program updates that I wrote for in recent weeks:

US Military’s Satellite-Launching XS-1 Space Plane Could Fly in 2019

DARPA has received authorization to spend $146 million on the next phases of the program, which is enough to select one of the three companies and move forward. It’s not enough to finish the program, so the selected company will need to come up with funds of its own. DARPA hopes to down select by the end of the year.

Boeing, Masten Space Systems and Northrop Grumman are the leads for phase 1 of the program. However, phases 2 and 3 are open to all U.S. aerospace companies. DARPA had an industry day for the project on April 29.

What lies at the end of the rainbow. Stratolaunch Systems, that's what. (Credit: Douglas Messier)

What lies at the end of the rainbow? Stratolaunch Systems, that’s what. (Credit: Douglas Messier)

Rocket for Giant Satellite-Launching Stratolaunch Airplane Remains a Mystery

Birdzilla remains more zilla than bird. The plane is still under construction, but the company has yet to announce what rocket(s) it will use.

The most recent update I’ve heard through the grapevine is that much of the aircraft is assembled. That’s a good sign, but it could also mean that much of the interior work — which can take a long time — remains to be done.

Last year, the company said it were considering more than 70 different booster configurations, which means they were talking to everyone and anyone with a rocket, an engine or plans for them.

In July, I asked Chuck Beames whether Burt Rutan & Scaled has once again put the flying machine ahead of the rocket, as they did with SpaceShipTwo. He said no, and assured me that they would make an announcement about the booster(s) in the fall.

That time came and went. Officials now say that they expect to make a series of announcements in the coming future.

4 responses to “XS-1 Moves Forward, Stratolaunch Booster Remains Mystery”

  1. Andrew Tubbiolo says:

    Wish I knew enough aerodynamics to run the numbers on the penalty of wing drag vs the volume for more propellant, with the possibility of drop tanks (like on a fighter jet), vs the fuel inefficiency of vertical landing? Has anyone ever seen a paper trading those off against each other, or have they done the computations themselves?

  2. Andrew Tubbiolo says:

    Different flight regime. That was a means of limiting the downward velocity vector that comes about because of the delay from aircraft drop to motor/engine ignition. That wing is more for attitude control, I doubt that wing would give much cross range, let alone a vehicle to glide to a landing at a speed that’s …. oh, about as sane as a F-104 or Mig-21. I’d hate to see the landing speed of a Rutan Pegasus wing.

  3. Andrew Tubbiolo says:

    If I were to take up the jon, and I will, I’d just do a drag term across a cross section for a velocity regime. Then integrate forward. Given Space X and BO playing with some whacky margins, I wonder if drop tanks, and even keeping the fuel hose attached after initial vertical motion would help with the margins. Yesterdays chart showing a RTB F9h has the same payload to GTO as a throw away F9 v1.2. That’s really stark.

  4. Jeff2Space says:

    Wings versus propulsive landing is a tricky trade-off. Both would seem to have razor thin margins (unpowered glide landing versus a very limited amount of fuel for vertical landing). While both impose a mass penalty, wings would seem to impose a higher drag penalty during launch. Both add the complexity of landing gear and active control systems.

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