Reading level:

Stratolaunch Roc

Scaled Composites · Air-launch carrier for hypersonic test vehicles · United States · Digital Age (2010–present)

Stratolaunch Roc — Air-launch carrier for hypersonic test vehicles
Open in interactive gallery →See aircraft like this on the live radar →

The Stratolaunch Roc is the largest aircraft ever built by wingspan — 385 ft (117 m), about 50% wider than the Hughes H-4 Hercules Spruce Goose that held the previous record from 1947 to 2019. Designed by Burt Rutan's Scaled Composites and built by Stratolaunch Systems in Mojave, California between 2011 and 2018, the Roc first flew on 13 April 2019. The aircraft was conceived as a high-altitude air-launch carrier for orbital rockets; after the 2018 death of Stratolaunch founder Paul Allen the company pivoted to hypersonic test-vehicle launch instead.

The configuration is unique. The Roc has two complete fuselages — port and starboard — connected by a 95-ft centre wing with the rocket / hypersonic-vehicle payload mount underneath. The port fuselage carries the cockpit and flight crew; the starboard fuselage carries flight-test instrumentation and a secondary cockpit position. Each fuselage uses three Pratt & Whitney PW4056 turbofans (six total, 56,750 lbf each), salvaged from used 747 airliners. The twin-fuselage layout reduces structural loads on the centre wing during air-launch separation — a critical concern given the 550,000-lb maximum payload.

The Roc made eight test flights between 13 April 2019 and 5 January 2024, gradually expanding the flight envelope from initial low-altitude handling tests to full payload-carriage configuration. Captive-carry of the Talon-A hypersonic test vehicle began in 2022; the first powered separation and launch came on 11 December 2023, when Talon-A1 separated from the Roc at 37,000 ft and accelerated to Mach 5+ on its own scramjet propulsion. Stratolaunch is currently contracted with the U.S. Department of Defense for hypersonic flight-test capacity through at least 2027.

The Roc operates from the Mojave Air and Space Port and Vandenberg Space Force Base. Future plans include carrying the larger Talon-Z reusable hypersonic vehicle (under development) and potentially returning to Paul Allen's original orbital-rocket air-launch concept if a customer emerges. As of 2026 the Roc remains the only large air-launch carrier aircraft in commercial service worldwide; the Northrop Grumman Pegasus carrier (a modified L-1011 TriStar) handles the smaller Pegasus orbital launch vehicle but is much smaller in MTOW class.

For Kids — a shorter, friendlier version

The Stratolaunch Roc is the biggest aircraft in the world by wingspan. Its wings stretch 385 feet from tip to tip. That is wider than a football field! It was built in Mojave, California, and first flew on April 13, 2019.

The Roc has two separate bodies joined together by one giant middle wing. One body holds the pilots and cockpit. The other body holds special test equipment and a second cockpit. A vehicle meant for hypersonic flight hangs underneath the middle wing.

The plane uses six powerful jet engines in total. These engines were taken from used passenger jets. Each fuselage has three engines, and together they give the Roc enough power to carry very heavy loads into the sky.

The Roc was first planned to launch rockets into orbit. But plans changed after the company's founder, Paul Allen, passed away in 2018. The team decided to use the Roc to test hypersonic vehicles instead. Hypersonic means flying faster than five times the speed of sound.

In 2023, the Roc successfully launched a hypersonic test vehicle for the first time. The twin-fuselage design helps reduce stress on the wings during launch. This makes it safer to drop heavy vehicles from up high.

Fun Facts

  • The Roc's wingspan is 385 feet — wider than a football field from end zone to end zone!
  • It is about 50% wider than the old record holder, a famous plane called the Spruce Goose.
  • The Roc has two separate fuselages, making it look like two planes joined at the wing.
  • All six of its jet engines were recycled from old passenger airplanes.
  • The Roc can carry a payload heavier than a fully loaded semi-truck — up to 550,000 pounds!
  • It took from 2011 to 2018 to build the Roc in the California desert.
  • The Roc launched its first hypersonic test vehicle in 2023.
  • Hypersonic flight means going faster than five times the speed of sound!

Kids’ Questions

Why does the Roc have two bodies instead of one?

The two bodies help spread out the weight of the heavy vehicle hanging underneath. This puts less stress on the wings when the vehicle is released. It makes the whole plane safer to fly with big payloads.

What does the Roc actually launch into the sky?

The Roc carries hypersonic test vehicles under its middle wing. It flies high into the atmosphere and then drops the vehicle. The vehicle then flies on its own at extremely fast speeds.

Who built the Stratolaunch Roc?

The Roc was designed by a famous airplane designer named Burt Rutan and his company, Scaled Composites. It was built by Stratolaunch Systems in Mojave, California. A man named Paul Allen started the Stratolaunch company.

How fast is hypersonic flight?

Hypersonic means flying faster than five times the speed of sound. Sound travels very fast, so five times that speed is incredibly quick. The Roc itself does not fly that fast, but the vehicles it launches do!

Variants

Stratolaunch Roc (sole airframe)
Single airframe built by Scaled Composites at Mojave, CA between 2011 and 2018. Twin-fuselage paired layout, 385 ft wingspan, six Pratt & Whitney PW4056 turbofans (recycled from used 747s). First flight 13 April 2019; eight flights through January 2024.

Notable Operators

Stratolaunch
Sole operator. Headquartered in Mojave, California. Operates the Roc from Mojave Air and Space Port and Vandenberg Space Force Base for hypersonic test-vehicle air-launch under contract to the U.S. Department of Defense.

Frequently Asked Questions

What is the largest aircraft ever built?

The Stratolaunch Roc is the largest aircraft by wingspan — 385 ft (117 m). The Antonov An-225 Mriya remains the heaviest by maximum takeoff weight (640 t vs. Roc's 590 t). The Hughes H-4 Hercules held the wingspan record from 1947 (320 ft) until the Roc broke it in 2019.

Why does the Stratolaunch have two fuselages?

The twin-fuselage layout reduces structural loads on the centre wing during air-launch separation. The 550,000-lb payload (orbital rocket or hypersonic test vehicle) is mounted under the centre wing between the two fuselages; releasing it cleanly without tail-strike or wing-bending requires the centre wing to span the payload, which is much easier with two outboard fuselages than one big central fuselage.

What does Stratolaunch carry?

Currently, the Talon-A hypersonic test vehicle, under U.S. Department of Defense contract. The first powered separation occurred on 11 December 2023, when Talon-A1 reached Mach 5+ after release at 37,000 ft. Future plans include the larger Talon-Z reusable hypersonic vehicle, currently in development.

Why was the Stratolaunch built?

Originally to air-launch orbital rockets for Microsoft co-founder Paul Allen, who founded Stratolaunch Systems in 2011. After Allen's death in October 2018, the company pivoted to hypersonic test-vehicle air-launch under DoD contract — a less ambitious but more commercially viable mission. The original orbital-rocket concept may return if a customer emerges.

How is the Stratolaunch different from the Pegasus carrier?

Northrop Grumman's Pegasus carrier is a modified Lockheed L-1011 TriStar that air-launches the small Pegasus orbital rocket. The Roc is much larger (550,000 lb payload vs. Pegasus's ~50,000 lb) and currently launches hypersonic vehicles rather than orbital rockets. Both are air-launch carriers; the Roc occupies the heavy end of the niche.

Sources

See Also