You can deep throttle on single shaft system by choking flow of fuel or oxygen between pump & combustion chamber. Problem is more with the tiny rocket engine that powers the pump, called a gas generator. That has to throttle *way* deeper than the main chamber.
Raptor is *very* complex, even for a staged combustion engine. We’re simplifying as much as possible with each iteration. Throttling down to ~50% is hard, but manageable. Going to 25% would be extremely tough, but hopefully not needed.
Since Elon Musk unveiled his Big [Expletive] Rocket (BFR) in Adelaide last month, there has been a lot of analysis of the engineering aspects. Musk’s Ask Me Anything session on Reddit was an engineer’s dream, with the billionaire providing detailed answers about the Raptor engines, thrust to weight ratios and a host of other technical issues.
Amid all the technical talk, there has been little attention paid to what a giant leap this venture is for Musk, SpaceX and possibly the entire human race. Not only will BFR be larger and more powerful than any other rocket ever built, the audacious things Musk wants to do with it – ranging from point to point transportation on Earth to satellite delivery to sending colonists to the moon and Mars – are on a scale never before attempted. They are certainly beyond anything contemplated by the world’s space agencies.
The U.S. Air Force has awarded an additional $40.8 million to SpaceX for the development of its Raptor rocket engine.
The funding, awarded under the Evolved Expendable Launch Vehicle program, involves the extension of a $33.7 million contract originally awarded in January. SpaceX agreed to spend $67.3 million under the jointly funded program under the original contract.
Elon Musk conducted an Ask Me Anything session on Reddit on Saturday. Below are selected responses to questions. A full list of questions and answers is located here.
Will be starting with a full-scale Ship doing short hops of a few hundred kilometers altitude and lateral distance. Those are fairly easy on the vehicle, as no heat shield is needed, we can have a large amount of reserve propellant and don’t need the high area ratio, deep space Raptor engines.
Next step will be doing orbital velocity Ship flights, which will need all of the above. Worth noting that BFS is capable of reaching orbit by itself with low payload, but having the BF Booster increases payload by more than an order of magnitude. Earth is the wrong planet for single stage to orbit. No problemo on Mars. (more…)
The U.S. Air Force issued a request for proposals (RFP) last Thursday for a new launch vehicle to handle national security space (NSS) requirements.
“The goal of the EELV acquisition strategy is to leverage commercial launch solutions in order to have at least two domestic, commercial launch service providers that also meet NSS requirements, including the launch of the heaviest and most complex payloads,” the proposal states.
“The Launch Service Agreements (LSAs) facilitate development of at least three EELV Launch System prototypes as early as possible, allowing those launch systems to mature prior to a future selection of two NSS launch service providers for Phase 2 launch service procurements, starting in FY20,” the proposal adds. (more…)
Later today, Elon Musk will stand on a stage at the International Astronautic Congress in Mexico and reveal his plans for sending humans to Mars and making humanity a multi-planet species.
His talk will be webcast on Tuesday, Sept. 27 beginning at 2:30 pm EDT. To access the webcast, please click here or connect on one of these websites: IAF website, IAC 2016 website and AEM website. Musk will hold a press conference afterward; it’s not known whether it will be webcast.
The description of the talk on the conference website gives us a hint about what lies ahead.
SpaceX Founder, CEO, and Lead Designer Elon Musk will discuss the long-term technical challenges that need to be solved to support the creation of a permanent, self-sustaining human presence on Mars. The technical presentation will focus on potential architectures for sustaining humans on the Red Planet that industry, government and the scientific community can collaborate on in the years ahead.
There are three questions that loom on the eve of the speech: What exactly is he going to propose? Who will pay for it? And how will he convince people it’s worth doing? A bit of parsing of the above description gives us some clues. (more…)
LOS ANGELES AIR FORCE BASE, Calif., Jan. 13, 2016 (SMSC PR) — Today the Space and Missile Systems Center awarded the first two Other Transaction Agreements (OTAs) for shared public-private investments in Rocket Propulsion System (RPS) prototypes to SpaceX for development testing of the Raptor upper stage engine and Orbital ATK for development of the Common Booster Segment main stage, the Graphite Epoxy Motor (GEM) 63XL strap-on booster, and an extendable nozzle for Blue Origin’s BE-3U/EN upper stage engine.
The initial government contribution to the SpaceX OTA is $33.6 million. The initial government contribution to the Orbital ATK OTA is $46.9 million. The Air Force is still in negotiations with the remaining offerors and subsequent awards, if any, will occur over the next few months.
SpaceX CEO Elon Musk did an interactive Ask Me Anything Q&A last night on Reddit. Here are some excerpts from that session.
Q. Previously, you’ve stated that you estimate a 50% probability of success with the attempted landing on the automated spaceport drone ship tomorrow. Can you discuss the factors that were considered to make that estimation?
In addition, can you talk more about the grid fins that will be flying tomorrow? How do they compare to maneuvering with cold-gas thrusters?
Elon Musk: I pretty much made that up. I have no idea 🙂
The grid fins are super important for landing with precision. The aerodynamic forces are way too strong for the nitrogen thrusters. In particular, achieving pitch trim is hopeless. Our atmosphere is like molasses at Mach 4!
Media reports indicate that United Launch Alliance (ULA) has decided to partner with Jeff Bezos’s Blue Origin company to produce a liquid-oxygen/methane engine to power the first stage of the Atlas V booster. An announcement is expected on Wednesday.
[Update: ULA and Blue Origin will have a press conference at the National Press Club in Washington, D.C., on Wednesday at 1 p.m.]
In June, ULA announced it had signed multiple study contracts with American rocket manufacturers for a replacement for the Russian-supplied RD-180 engine. The company said it planned to make a decision by the fourth quarter of this year.
BAY ST. LOUIS, Miss. (NASA PR) — An April 21 ribbon-cutting ceremony at NASA’s Stennis Space Center near Bay St. Louis, Miss., marked the beginning of a new NASA and Space Exploration Technologies Corp. (SpaceX) partnership aimed at continuing to propel America’s burgeoning commercial space program forward and enhance utilization of NASA’s advanced test facilities. Several Mississippi leaders joined NASA and SpaceX representatives for the ceremony including Gov. Phil Bryant, U.S. Sen. Thad Cochran and U.S. Rep. Steven Palazzo.
SpaceX signed a Space Act Agreement with the space agency last fall to test components of its methane-fueled Raptor rocket engine on the E-2 Test Stand at Stennis. SpaceX is developing the Raptor as a reusable engine for a heavy-lift launch vehicle.