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January 12, 2012

Improved Spacex Merlin Engines Enable Vastly Superior Falcon Heavy and Even better future systems

Nasaspaceflight talks about Spacex starting up their reusable Faclon 9 rocket development program this year and the advances in the Merlin 1D engine that could fly this year.

Upcoming upgrades to the engine (Merlin 1D) will provide a vast improvement in performance, reliability and manufacturability – all of which could provide a timely boost to aiding the potential for success for the fully reusable Falcon 9.

Increased reliability: Simplified design by eliminating components and sub-assemblies. Increased fatigue life. Increased chamber and nozzle thermal margins,” noted SpaceX in listing the improvements in work.

Improved Performance: Thrust increased from 95,000 lbf (sea level) to 140,000 lbf (sea level). Added throttle capability for range from 70-100 percent. Currently, it is necessary to shut off two engines during ascent. The Merlin 1D will make it possible to throttle all engines. Structure was removed from the engine to make it lighter.

Improved Manufacturability: Simplified design to use lower cost manufacturing techniques. Reduced touch labor and parts count. Increased in-house production at SpaceX.

Spaces will begin testing a vertical propulsion landing system later this year. This is the research and development effort designed to help us learn more about propulsive landing systems to advance plans for producing reusable rockets.

This is a long-term project. SpaceX must successfully complete extensive testing before we will see reusable vehicles.

Even for an expendable launch vehicle, where you don’t attempt any recovery, you only get maybe two to three percent of your lift-off weight to orbit. That’s not a lot of room for error.

OK, now let’s make it reusable. You have to strengthen the stages, add a lot of weight, a lot of thermal protection – a lot of things that add weight to that vehicle – and still have a useful payload to orbit. You’ve got to add all that’s necessary to bring the stages back to the launch pad to be able to re-fly them and still have useful payload to orbit.
test firing a Merlin 1D

This is why the record high thrust to weight ratio of the Merlin D (160 thrust to 1 weight) is critical. By getting lift off weight to orbit up to 3.77 percent (117,000 pounds to LEO versus 3.1 million pounds of liftoff weight) then there is 50,000 pounds that could be used for reusability (thermal protection, strengthened stages, return fuel) while leaving 67,000 pounds for payload to orbit.

There are more improvements planned for the Merlin engines and better engines would mean better one time rockets and more capacity for any potential reusable rocket.




Brainstorming Merlin 2 Possibilities

At the AIAA Joint Propulsion conference on July 30, 2010 SpaceX McGregor rocket development facility director Tom Markusic shared some information from the initial stages of planning for a new engine. SpaceX’s Merlin 2 LOX/rocket propellant-fueled engine, capable of a projected 7,600 kN (1,700,000 lbf) of thrust at sea level and 8,500 kN (1,920,000 lbf) in a vacuum and would provide the power for conceptual super-heavy-lift launch vehicles from SpaceX, which Markusic dubbed Falcon X and Falcon XX. Such a capability would result in an engine with more thrust than the F-1 engines used on the Saturn V.

Slated to be introduced on more capable variants of the Falcon 9 Heavy, the Merlin 2 “could be qualified in three years for $1 billion,” Markusic says. By mid-August, the SpaceX CEO Elon Musk clarified that while the Merlin 2 engine architecture was a key element of any effort SpaceX would make toward their objective of "super-heavy lift" launch vehicles—and that SpaceX did indeed want to "move toward super heavy lift"—the specific potential design configurations of the particular launch vehicles shown by Markusic at the propulsion conference were merely conceptual "brainstorming ideas", just a "bunch of ideas for discussion."
Wikipedia compared the Spacex Falcon Rockets

Some older plans for Spacex Rockets

The Falcon 9 Heavy was replaced with a superior Falcon Heavy.



Pica-X heat shield can withstand hundreds of returns from low earth orbit

Air and Space magazine - SpaceX has even been able to advance the state of the art. For the Dragon’s heat shield, the company chose a material called PICA (phenolic impregnated carbon ablator), first developed for NASA’s Stardust comet-sample-return spacecraft. Rejecting the prices they were getting from the manufacturer, they took advantage of help from NASA’s Ames Research Center to make it themselves. According to Mueller, SpaceX’s material, called PICA-X, is 10 times less expensive than the original, “and the stuff we made actually was better.” In fact, says Musk, a single PICA-X heat shield could withstand hundreds of returns from low Earth orbit; it can also handle the much higher energy reentries from the moon or Mars.

Safety from Simpler Design

Some observers have questioned whether SpaceX’s smaller workforce can build and operate a vehicle safe enough for astronauts to fly. But former astronaut Ken Bowersox, who joined SpaceX in 2009 as vice president of astronaut safety and mission assurance, says safety stems mostly from a vehicle’s design. Bowersox, who flew four space shuttle missions as well as the Russian Soyuz, says that at NASA the shuttle’s complexity required a large organization to manage the risks. “People started to think that that’s the only way you can operate. And I have to say that I would’ve been in that boat if I hadn’t been sent off to train in Russia,” where the workforce is much smaller. Because the Soyuz is far simpler than the shuttle and includes an escape system, he says, it is safer despite the inevitable human errors. Dragon follows the same design philosophy.

Human-rating the Dragon will require development and flight tests of a launch abort system, which could cost nearly a billion dollars. Before astronauts are allowed to fly it, NASA will subject the craft to an intensive review. Lindenmoyer, the commercial crew program manager, thinks Musk and his team can meet the agency’s standards. “Everybody has a perception of SpaceX, what they must not be doing,” he says. “But when you get in there and you’re shoulder to shoulder with them, you quickly learn that that is not the case. Believe me, I was skeptical at first. Do they follow all those standards for quality and safety? Yes, they do. They absolutely do.”

Insistence on Reusability

The insistence on reusability “drives the engineers insane,” says Vozoff. “We could’ve had Falcon 1 in orbit two years earlier than we did if Elon had just given up on first stage reusability. The qualification for the Merlin engine was far outside of what was necessary, unless you plan to recover it and reuse it. And so the engineers are frustrated because this isn’t the quickest means to the end. But Elon has this bigger picture in mind. And he forces them to do what’s hard. And I admire that about him.”

In spite of the extra effort trying to get reusability as well, Spacex spent $440 million to get from design to the first Falcon 9 launch. This would have cost other rocket companies three times as much or more (without any attempt at reusability).

Even Competitors want Spacex to Succeed

SpaceX has the immediate hurdle of converting the doubters with a track record of low cost and reliability. Rivals know that success would hit the rocket business like a tsunami, and at least one aerospace engineer greets that prospect with a mix of hope and doubt. “Honestly, as an American, I want them to succeed,” says Mike Hughes, who works for a company (he asked that it not be named) planning a competing crew vehicle.

A Falcon 9 launch costs an average of $57 million, which works out to less than $2,500 per pound to orbit. That’s significantly less than what other U.S. launch companies typically charge, and even the manufacturer of China’s low-cost Long March rocket (which the U.S. has banned importing) says it cannot beat SpaceX’s pricing. By 2014, the company’s next rocket, the Falcon Heavy, aims to lower the cost to $1,000 per pound.

A reusable rocket will bring the cost below $100 per pound.

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