Inside The Roc's Lair


The massive size of the carrier aircraft now in assembly at Mojave, California, for Stratolaunch Systems’s space launch program is apparent for the first time in these rare stills taken from footage shot for a recent news story by KGET 17, a Bakersfield TV station.

One of the two enormous twin fuselage sections under assembly. Individuals working on the structure are ringed in red circles for scale.

The NBC affiliate was granted unprecedented access to film the gargantuan vehicle, dubbed ‘Roc’ after the giant bird of prey in Middle East mythology, as part of an overview report on space-related developments at Mojave. Although Stratolaunch has produced computer-generated images and videos of the Roc, the TV footage is the first time images of the real vehicle in a substantial state of completion have been shown.

Another view of a boom with a worker circled for scale on part of the wing section.

Built for Stratolaunch by Scaled Composites, the Roc will be the largest aircraft ever made with a wingspan of 385 ft. This compares to 320 ft for the Hughes H-4 Hercules (Spruce Goose), 290 ft for the six-engined Antonov An-225, 262 ft. for the Airbus A380, and 225 ft. for the Boeing 747-8. Powered by six reconditioned Pratt & Whitney PW4056 engines salvaged along with other parts from two ex-United Airlines Boeing 747-400s, the twin-fuselage carrier aircraft resembles a vastly enlarged version of the Scaled-built WhiteKnightTwo developed for Virgin Galactic.

The deep chord of the center wing section and narrow cross section of the aft fuselage booms is evident in this overview.

In the news report, Scaled Composites president Kevin Mickey says the company has so far built “roughly 200,000 lb. of composite structure” for the vehicle. He adds for effect that if the Roc was positioned on the centerline of the 50 yard line of an American football field the wingtips would hang over the goalposts “roughly 15 ft. on each side.”

Each of the twin fuselages of the Roc is 238-ft. long and, when complete, will be supported by 12 main landing gear wheels and two nose gear wheels for a total shipset of 28 wheels. The vehicle will be flown by a three-person crew from a cockpit situated in the right hand fuselage. The three-stage Thunderbolt rocket will be carried aloft for launch mounted beneath the wing center section.  

Flight tests are scheduled to begin in around a year’s time, with initial launch operations starting in 2018. According to the latest information from Stratolaunch, the Orbital Sciences-built Thunderbolt will be 131-ft long, and weigh around 550,000 lb. Overall weight of the Roc and Thunderbolt will be 1.3 million lbs. The launch vehicle is designed to put 13,500 lb. into a 220 naut. mile, 28.5 degree (LEO) orbit.  Payloads will be enclosed within a 16.4-ft diameter fairing. The three-stage vehicle will use ATK-provided solid rocket motors for the first and second stages, while the third will be powered by two liquid-fueled Aerojet Rocketdyne RL10C engines.

Discuss this Blog Entry 22

on Feb 25, 2015

Seems like a very expensive method to determine the largest size of bird that can fly. Paper and pencil and little bit of physics would make more sense.

I wonder what the strength to stiffness ratio profile from wing tip to wing tip should be to prevent it from going into resonance? GL

on Mar 2, 2015

I wonder what the test limits were in the wind tunnel tests? Did they account for the worst case turbulence and especially during a maximum banked turn? I can see this thing cracking in two, the wing span in just too long. They better have fast computers on board. GL

on Feb 25, 2015

This aircraft is going to require a very wide taxiway and runway. The design group VI category aircraft wingspan only goes up to 262', which this exceeds by 123'. The distance between the main gear on the twin fuselages is unstated, but looks to exceed 52' which is the airport reference code group F maximum. Given the wing tip clearances; gear width; engine locations hanging over the taxiway and runway edges; turn radius; and base weight of 550,000 pounds this aircraft is going to require a very specialized airport environment. Are they planning on operating out of an old Air Force B-52 base with 250' wide runways?

on Feb 25, 2015

Hi WingNut48, details remain sparse but other than flight testing at Mojave, Stratolaunch says operations are being studied from KSC, VAFB and - surprisingly given its 8,750 ft max runway length - Wallops Flight Facility.

on Feb 25, 2015

As a space plane it will require a runway like at the Kennedy Space Ctr. or Vandenberg not of course from a major airline hub.

on Mar 1, 2015

It's not a space plane in the sense of flying into space. Instead, it will fly up to 50,000 feet -- ten miles -- then release the Thunderbolt launcher, which will propel the payload into orbit.

on Feb 26, 2015

Geez. Poor Russia. Now they will have to build something even bigger.

on Feb 27, 2015

"Geez. Poor Russia. Now they will have to build something even bigger."

And then leave it abandoned in a field for thirty years.

on Feb 26, 2015

I wonder how many 1%ers it will take to achieve the projected ROI?
Meanwhile, Rome is still burning...

on Feb 26, 2015

One percenters? I think you're confused. This is a satellite launch system --not a space tourism business. It does not involve the "excess capital" usually associated with the ultra-wealthy, except to the extent that the capital to build the company is coming from a wealthy private individual's pockets (instead of from taxpayers like you and me).

on Feb 27, 2015

But Paris was spared

on Feb 26, 2015

I bet test flying this beast is going to be really interesting. And the first time they drop a 550,000 pound load, that'll be interesting, too.

on Feb 26, 2015

Probably comparable to a WWII Lancaster dropping the 10-tonne Grand Slam or a B-36 dropping the T-12, weighing 43,600 lb. Could one expect some flapping of the wing? Or could the booster be separated in a VERY, VERY mild (near-zero-g) pushover ? :-). A question for the designer...

on Feb 27, 2015

Yes, but more so. As a percentage of aircraft weight when the load is released, the ROC dropping the rocket will be dumping more than the Lancaster or the B-36. Between the load falling down and the aircraft springing upwards, I doubt they'll have to worry about getting sufficient separation before igniting the rocket. They might try the pushover technique but that might cause a performance penalty on the rocket. They might try a mild zoom climb just before release so the rocket's momentum is going upwards instead of downwards. At this point, who outside of StratoLaunch and Scaled knows?

on Apr 27, 2015

Good idea, the zoom-climb-with-a mild-pushover-again, it haven't occurred to me. But imho it would be a sort of trading the speed for altitude/attitude, as there is probably not much of the SEP for any release-altitude shenanigans? The guys at Mojave certainly must know their trade:-).

on Feb 26, 2015

The report from KGET is fascinating. Here is a short link to their televised report:

on Feb 27, 2015

Rockets science all of 80 or so years old is still a very risky business not only in terms of human lives but in the astronomical costs, that is why I think that only governments can afford it. In this case at least there is a real practical application i.e. placing satellites in orbit as apposed to Virgin Galactic's so called space adventure that reaches a mere 60 mile altitude charging very rich people a quarter of a million dollars per head to brag about "having been to space".

on Mar 2, 2015

shungo717 - This blog is about aviation...not economics...but your post warrants a response. The 'astronomical costs' of 'rocket science' is ONE specific reason 'governments' should stay out of it.

NASA was 'robbed' of true the government!

'Government' as a concept and institution is a necessary evil - not a solution for every problem or task on this planet. 'Government' has corrupted, polluted, bankrupted and stunted everything it has ever touched or become involved in. EVERYTHING.

Government is a huge problem - not a solution. In March of 2015 it costs $4.67 for Samsung to manufacture a Galaxy cell phone. It costs the U.S. federal government...$.145 manufacture a one cent coin.

Class is let's get back to the regularly programmed subject...

on Mar 3, 2015

Hobbs indeed this is a blog about aviation so why you brought up the costs to make a cell phones or coins. Economic issues can not be ignored and I agree that governments have a tendendy to overspend sometimes with the kind assistance of private enterprise contractors, weapons manufacturers, et all.

on Apr 4, 2015

I'm wondering how 'they' got around the vagaries of 'scale effect'; where the strength of the structure changes with the increase in size. I believe that they must have come up with some "PFM" (Pure Flippin' Magic) to pull this one off.

on Feb 18, 2016

Mel, we got around the vagaries of 'scale effect the only way you can when "Fast prototyping" by designing what we think will work in a certain area, moving ahead with the build while designing more of the aircraft, analyzing the computer model when time permits, finding that it doesn't work, redesigning the bad stuff while tearing some of what we just built apart and building in the fixes. Sounds like the long way around but we are still the leaders in our niche "Low cost, fast prototyping" and our successes far outweigh our failures. Stratolaunch operations? Rumor has it that the Mojave Air & Space Port would work just fine. Though a second option near the East coast to land in an emergency is probably being talked about. Oak Tree, where is your sence of adventure, not to mention common sense? "Pencil and paper and a bit of physics" this isn't about measuring "Members" this is about "Doing Stuff". As for Government invention/intervention, Len said it perfectly.

on Feb 29, 2016

ROC Builder - this project is absolutely fascinating on so many fronts. If you can talk about it, how are you curing a carbon layup that big? Is it room temperature cure, or have you built an oven or (gasp) autoclave that big?

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