While many beleaguered U.S. aerospace manufacturers are trimming back amid continuing uncertainty over the nation's long-term goals, California-based SpaceX is ramping up plans to become the world's largest producer of rocket engines in less than five years, manufacturing more units per year than any other single country.

Outlining SpaceX's ambitious growth strategy, President Gwynne Shotwell says a production increase is aimed at supporting the assembly of engines for the coming flurry of Falcon 1 and 9 launches. The company also continues to bolster its workforce, passing the 1,500-employee mark for the first time at the start of August after seeing a 50% uptick in payroll last year.

“We have built about 60 engines so far this year, and will build another 40 by year-end,” says Shotwell. Speaking at the American Institute of Aeronautics and Astronautics Joint Propulsion Conference here, Shotwell explains that the eventual “plan is to build up to 400 engines per year, that's our target.” The expansion is built on booked revenues of $3 billion through 2017, part of which was earned by orders for 14 new Falcon 9 launches placed “within the last year,” she says. SpaceX is also “negotiating three more right now,” she adds. The launch manifest lists 40 sold flights, including 33 Falcon 9s, plus five options.

“The momentum increased last year, and hopefully if all goes well we'll be docking with the International Space Station [ISS] in December,” says Elon Musk, SpaceX founder and chief technical officer. Describing the planned launch of its second test Dragon spacecraft as its “top priority,” Musk says the current plan calls for the third Falcon 9 launch vehicle to place the Dragon in orbit from where it will rendezvous and berth with the ISS on Dec. 9. The Commercial Orbital Transportation Services (COTS) flight is required to clear the way for the first of 12 regular cargo delivery flights ordered under the $1.6 billion Commercial Resupply Services contract NASA awarded the company in 2008.

Following the COTS flight, SpaceX's focus will shift to convincing the U.S. Air Force and National Reconnaissance Office that the Falcon 9 can provide a competitive alternative to United Launch Alliance's Atlas V and Delta IV Evolved Expendable Launch Vehicles. “That's our next big priority after ISS,” says Musk, who notes that the company recently began construction of its Falcon Heavy launch site at Vandenberg AFB, Calif. The first Falcon Heavy flight is targeted for 2013.

All Falcon 9 flights up to and including the sixth will be powered by the kerosene/liquid oxygen 95,000-lb.-thrust Merlin 1C, with the Merlin 1C-Vac derivative powering the upper stage. Development of the more powerful, 140,000-lb.-thrust Merlin 1D, which will equip the Falcon 9 from the seventh flight onward, is now underway. More than 150 firings have been accomplished at the company's Rocket Development Facility in McGregor, Texas, since the effort began in February.

Revealing several new details of the 1D, Tom Mueller, propulsion engineering vice president, says the engine is designed to produce 155,000 lb. vacuum thrust and have a chamber pressure at “the sweet spot” of roughly 1,410 psia. “We've also increased the nozzle expansion ratio to 16 [compared with 14.5 on the Merlin 1C],” says Mueller, who adds that the initial engine “is doing better than we hoped.” The engine is designed for an Isp (specific impulse) of 310 sec. and has a thrust-to-weight ratio of 160:1. “We took structure off the engine to make it lighter. The engine we shipped [for test] to Texas was a development engine and hopefully the production engines will be even better,” he says.

The 1D design incorporates many lessons learned from the earlier Merlins and is of a simpler design with an increased fatigue life. “We've added the ability to throttle between 70% and 100%. Currently we have to shut off two engines during ascent, and on this we will be able to throttle them all,” he says. The development will also provide the basis for a 1D-Vac version intended for the second stage of the planned Falcon Heavy. “There are no plans to build a 1E. It's going to be a 1D with the same turbopump.”

For SpaceX's longer-term ambitions to deliver cargo and humans to Mars, Musk says plans to develop a “super-efficient, staged-combustion engine” could be made official “later this year, or early next.” Although no further details of the engine, variously known as the Raptor or BFE (Big Falcon Engine), are being revealed, the company last year showed a concept for a 150,000-lb.-thrust liquid oxygen/liquid hydrogen engine with an Isp of 470 sec.