In November 1947 the H-4 Hercules, also known as the “Spruce Goose,” took flight in California. The flight logged air time of just 26 seconds and covered about a mile, but it marked the first flight of the largest aircraft ever built. That was the only flight the plane ever made, but it amazingly held the record for the largest aircraft by wingspan to ever fly for more than 70 years. That title fell this weekend as the Scaled Composites Stratolaunch took flight over the Mojave Desert.
Sporting a twin fuselage configuration, the Stratolaunch design is unmistakable. The wingspan stretches an incredible 385 feet, besting the Spruce Goose by 65 feet. The aircraft is powered by three Pratt & Whitney PW4056 engines on each side, all mounted outboard of the fuselage. Like the engines, many of the control systems on Stratolaunch were adapted from the 747 to help reduce development costs on the aircraft.
At Mojave Air and Spaceport this morning once again hoping to catch the first flight of the world’s largest plane. Roc, as the aircraft is known, is now sitting at the end of runway 30 poised to make aviation history. @Stratolaunch @NASASpaceflight pic.twitter.com/ViFMoJfs8b— Jack Beyer (@thejackbeyer) April 13, 2019
Taking flight, with some limits
The Stratolaunch inaugural flight was a far more coordinated effort than that of the Spruce Goose. Among other things, everyone knew it was happening, not just the pilot at the controls. And Stratolaunch will almost certainly fly more than once, unlike the H-4. Stratolaunch is privately funded while the Spruce Goose was developed under a military contract during World War II; the contracts, delays in delivering the plane and the resulting uproar over wasteful spending are part of the legacy of that aircraft.
As @DJSnM stated @NASASpaceflight, this Stratolaunch aircraft has a gigantic wingspan (even longer than the Saturn V is tall). Thought I'd put this together to compare. It is always hard to get an idea of scale until you see something like this (note the insignificant human). 🤔 pic.twitter.com/bBAaIV1w3r— Marcus House (@MarcusHouseGame) April 14, 2019
Similarities between the two programs also exist. Both were the brain child of highly motivated, wealthy men (Howard Hughes and Paul Allen). Both were designed to carry a massive payload, though the Stratolaunch’s 550,000 pound external payload far surpasses that of the H-4. Questions also remain about the viability and need for the Stratolaunch, similar to the history of the H-4 that was years late to market.
Scaled Composites intends for the Stratolaunch to carry rockets from the ground to 35,000 feet, taking advantage of the 550,000 cargo capacity. Those rockets will then be deployed at altitude. Initially developed with the SpaceX Falcon9 as a possible payload, Scaled Composites eventually moved on to plans for its own series of in-house built launch vehicles. This family of launchers would enable the craft to deliver launch services customized to the payload and even mix-and-match customers on some flights, reducing costs. Plans to develop those launchers were shelved in early 2019. Today the Stratolaunch spec calls for the ability to launch as many as three Pegasus-XL rockets from the carrier, each able to deliver a relatively small (half ton) satellite to low-earth orbit (LEO).
Many of the other benefits initially envisioned by Stratolaunch remain in place. The high-altitude rocket release reduces impact of weather on a launch schedule. Using the Stratolaunch should also increase the viability of multiple launch locations, as the extensive ground infrastructure is not required, though a 12,000 foot runway capable of handling an extra-wide aircraft still is. Insurance costs can also be reduced by performing the rocket discharge over the ocean where the impact of a failure is lower than if over land.
While all those factors add value to the program the potential for Stratolaunch to realize commercial success remains limited. Indeed, some are dubbing the aircraft the “Space Goose,” a nod to its Spruce Goose ancestor. That name is not meant to inspire confidence.
Competition in the satellite launch industry is hotter than ever. While SpaceX was initially a partner it is now a huge competitor, able to carry larger satellites and demonstrating the reliability of its services on a regular basis. Blue Origin and SLS also offer large launch services and potentially “ride sharing” arrangements where many smaller satellites can all be launched together, helping to reduce costs. Arianespace continues to develop its larger Ariane 6 launcher while also pursuing options for smaller payloads. Other companies such as Rocket Labs offer reliable launching of smaller satellites to LEO targets. Astra Space is another player, though its initial launch failed in late 2018. Virgin Galactic hopes to deliver a similar launch platform as Stratolaunch, using a modified 747 as its carrier.
Fortunately for all these launch companies the market for such services appears to be strong. Multiple new LEO communications constellations, made up of hundreds to thousands of smaller satellites, are in the works. It is almost certain that they will not all take flight, but the potential for such will help keep launch operators busy for the next several years while figuring out which of the satellite operators will survive.
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