New Oxygen Preburner Firings a Major Step Toward Rekindling US Hydrocarbon Rocket Engine Leadership

Sub scale oxygen preburner has begun initial firing tests in Sacramento Calif. as part of the U.S. Air Force Hydrocarbon Boost Technology Demonstrator program. Photo Credit: Aerojet Rocketdyne

Sub scale oxygen preburner has begun initial firing tests in Sacramento, Calif., as part of the U.S. Air Force Hydrocarbon Boost Technology Demonstrator program. Photo Credit: Aerojet Rocketdyne

The U.S. Air Force (USAF) and its rocket engine contractor Aerojet Rocketdyne (AJRD) have achieved a major milestone toward a new U.S. state-of-the-art capability to develop powerful next generation hydrocarbon rocket engines. The achievement involves completion of the first in a series of hot-fire tests on a sub-scale oxygen-rich pre-burner, built by ARJD for the USAF’s Hydrocarbon Boost Technology Demonstrator (HBTD) program.

While America once led the world in kerosene and RP-fueled rocket engine technology, the U.S. has lost such hydrocarbon rocket infrastructure and lags behind Russia, specifically with the Energomash RP-1/liquid oxygen RD-180 that powers the proven and reliable United Launch Alliance (ULA) Atlas-V. 

There are two major rocket engine cycles. One is called a “gas generator cycle,” where gases used to drive an engine’s turbopump are exhausted by the pump, giving a somewhat ragged looking rocket plume due to this flaming exhaust vented beside more distinct rocket nozzle plumes.

As this diagram shows, the oxygen-hydrogen powered Space Shuttle RS-25 Main Engine has pre burners, but no powerful U.S. hydrocarbon engine does, a deficiency the USAF program seeks to correct. Photo Credit Aerojet Rocketdyne

As this diagram shows, the oxygen-hydrogen powered Space Shuttle RS-25 Main Engine has pre burners, but no powerful U.S. hydrocarbon engine does, a deficiency the USAF program seeks to correct. Photo Credit Aerojet Rocketdyne

The other cycle is the “staged combustion cycle,” where a share of the propellant—be it kerosene or oxygen or both—is first burned in a pre-burner. The resulting hot gas is first used to power the engine’s turbines and pumps, then, instead of being dumped as with the gas generator cycle, that exhausted gas is injected into the main combustion chamber, along with the rest of the propellant to generate powerful thrust. The two stages that make up the staged cycle propulsion are from the pre-burner stage, then combustion chamber stage.

A key advantage of staged combustion is that it gives an abundance of power, which permits very high chamber pressures and the use of high expansion ratio nozzles. These nozzles give better efficiencies at low altitude critical to the flight in the moments after liftoff.

The disadvantages of staged cycle engines include harsh turbine conditions, exotic plumbing to carry the hot gases, and complicated feedback and control. The U.S. mastered all of these for the Space Shuttle RS-25 Main Engine design that used cryogenic oxygen and hydrogen propellants and a preburner for each.

According to Aerojet Rocketdyne an oxidizer preburner combusts hydrogen and oxygen at an extremely fuel-rich mixture ratio, and thus supplies hot gas at variable rates to drive the engines high-pressure oxidizer turbo pump. The operating level of the oxidizer preburner is controlled by regulating the oxidizer flowrate by means of the oxidizer preburner oxidizer valve. Welding the injector into the top of the engine’s Hot Gas Manifold forms the combustion area and places it immediately above the pump turbine.

“Throughout the sub-scale fabrication and facility checkouts, we’ve documented a number of lessons learned that have directly influenced a full-scale pre-burner design. We are looking forward to what more we will learn during the hot-fire test series,” said Joe Burnett, program manager of the Hydrocarbon Boost Technology Demonstrator program at Aerojet Rocketdyne.

AJRD states, “In coming months, multiple injector configurations will be tested to evaluate the performance and stability parameters that are critical for a high-performance, high-reliability liquid oxygen/kerosene rocket engine.”

According to the USAF, typical parameters for an oxygen preburner are:

  • Mixture: A full 100 percent of the engine’s oxygen flow will be be mixed with 4 percent of the RP flow.
  • Losses: There are no secondary gas flow losses en route to the thrust chamber.
  • Performance: The resulting high pump and turbine speeds will equate to higher combustion chamber pressures producing higher thrust.

The sub-scale test series will be used to aid the design and development of the full-scale pre-burner and engine development. An oxygen-rich pre-burner is one of the enabling technologies of the Oxygen-Rich Staged Combustion (ORSC) cycle needed to provide high thrust-to-weight and performance regardless of hydrocarbon fuel type, both USAF and AJRD documentation says.

Under program direction of the Air Force Research Laboratory (AFRL), Aerojet Rocketdyne is designing, developing, and testing the HBTD engine. Its technologies are directed at achieving the goals of the Rocket Propulsion for the 21st Century (RP21) program, formally known as Integrated High Payoff Rocket Propulsion Technology, or IHPRPT.

Russian RD-180 being checked out near Moscow, Russia. It and the four-chamber RD-170 are only large hydrocarbon engines given more thrust with preburners. Photo Credit Energomash

Russian RD-180 being checked out near Moscow, Russia. It and the four-chamber RD-170 are only large hydrocarbon engines given more thrust with preburners. Photo Credit Energomash

Designed to generate 250,000 pounds of thrust, the engine technology uses liquid oxygen and liquid kerosene (RP-2) in the first U.S.-developed demonstration of the ORSC cycle. It has been designed as a re-usable engine system, capable of powering up to 100 flights, and features high-performance long-life technologies and modern materials, said the Air Force and its contractor.

Burn-resistant, high-strength alloys, manufactured using novel technologies, will be used throughout the engine. Manufacturing parameters of some of the alloys have been developed under a joint effort with the Air Force, known as the Metals Affordability Initiative or MAI, said AJRD.

These advanced technologies will be matured sufficiently throughout the program to support the next generation of expendable launch system development efforts. It also will help in the rapid turn-around usability for future re-usable launch systems.

The data from this test effort will be used by other Air Force development programs such as the Advanced Liquid Rocket Engine Stability Tools program (ALREST) to further advance the state-of-the-art capabilities in combustion stability modeling.

Previously, Aerojet Rocketdyne designed and supplied the oxygen-rich and fuel-rich pre-burners for the Air Force’s Integrated Powerhead Device (IPD) demonstration engine, the world’s first full-flow staged combustion rocket engine.

“The design lessons learned and test approach from the IPD pre-burners have been leveraged for the HBTD pre-burner architecture,” Aerojet Rocketdyne believes.

 

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66 comments to New Oxygen Preburner Firings a Major Step Toward Rekindling US Hydrocarbon Rocket Engine Leadership

  • W Eubank

    About 20 years too late. The USAF should never have allowed Lockheed-Martin to use a Russian made engine on the Atlas III and V

    • SArmstrong

      It’s easy to forget that Lockheed-Martin was encouraged to look for Russian rocket engines by the U.S. State Department who also got the USAF to allow it even though the original EELV requirements dictated a US made engine. The State Department was concerned at the time about out of work Russian rocket scientists looking for work in rougue nations due to the break up of the Soviet Union. Politics created the situation and politics made it untenable.

  • john hare

    Seems an odd size for the current stable of LVs. Four of them for an Atlas or Antares might fit, and might give some engine out capability. I wonder if this is in support of a larger engine or considered an end in itself.

    I also wonder how much this engine, or its’ derivatives, can be marketed. If it has little projected use, then it’s just another subsidized research project that will fade when its’ support does. OTOH, if it heralds a family of affordable and high performance first stage engines, then it will help America in regaining world launch market. Dense fuels for first stages are an excellent choice when properly done. Upper stages, not so much.

    • The 250,000 pounds of thrust for this engine in comparable to the older RS-27 family of engines. I would speculate that AR is using legacy hardware for much of the thrust chamber and nozzle for this new engine except that it replaces the separate gas generator-driven turbopump of the old RS-27 with a new, more efficient staged combustion system.

  • Maybe there looking into hydrocarbon engines because, as Mike Griffen said, “There’s more hydrogen in a gallon of RP-1 than in a gallon of liquid hydrogen.”?

    • Gary Church

      No advantage overcomes 100 seconds of Isp or several million pounds of thrust available with no moving parts. Hydrogen and solid fuel are the best mix- kerosene is obsolete.

      • In your opinion. Many others do not share your opinion such as teams of engineers and scientists who specialize in various aspects of rocket technology with centuries of cumulative experience and who actually design and build hardware for a living for various companies and corporations like Aerojet Rocketdyne, SpaceX, Blue Origins, ULA, OSC and others along with the business people who manage these team and make decisions as well as the stockholders and others who invest in these companies.

        And for the record, large solid rocket motors in the multi-million pounds of thrust class do have moving parts despite your claim contrary. In the case of the Space Shuttle SRBs, those moving parts included the nozzles and hydraulic power units that moved them. Admittedly these are mechanically simpler than modern liquid rocket engines that employ turbomachinery but they are moving parts nonetheless.

        • john hare

          It’s been a while since I ran even a BOTE trade on the difference for first stage use. This is based on clean sheet designs based on rough history of engine and tanks. I assumed here that the requirement was to impart 5,000 m/s to a 500 ton upper stage. I assumed a T/W of 125 for the Kero/LO2 engines and 75 for the LH2/LO2 engines. Propellant density of 1 for the Kero/LO2 and 0.31 for the LH2/LO2 tanks. Hydrogen first stages also have requirements for higher T/W off the pad to avoid excess gravity losses. I use an average Isp of 420 for the LH2/LO2 stage and average 320 for the Kero/LO2 stage.

          H2 Kero
          mass ratio 3.28 4.77
          GLOW tons 2,129 2,945
          thrust tons 3,200 3,600
          tons of engine 42.7 28.8

          propellant tons 1,480 2,338
          tank cubic meters 4,736 2,338
          tank mass at 20 kg/m3 90.7 tons 46.8 tons
          upper stage tons 500 500
          dry mass in tons available
          for controls etc 12 41

          This was just a fast BOTE trade that could apply to a first stage. Upper stages and beyond reverse this due to the multiplier effect of mass on the lower stages. But just a fast figure as I did here suggests that kerosene first stages delivering 5,000 m/s to an upper stage will have engines 2/3 and tanks 1/2 the mass of a hydrogen stage for the same job. Given that hardware is far more expensive than propellant, it would seem that dense propellant lower stages have a long history ahead of them.

          • Gary Church

            “-an upper stage will have engines 2/3 and tanks 1/2 the mass of a hydrogen stage for the same job.”

            Guess we should have used kerosene for the Saturn V upper stages. Funny how everyone else seems to think that hydrogen is how we got to the Moon. You sound like a rocket scientist but why do the history books say you are making this stuff up?

            • Joe

              The full sentence reads:

              “But just a fast figure as I did here suggests that kerosene FIRST STAGES delivering 5,000 m/s to an upper stage WILL HAVE engines 2/3 and tanks 1/2 the mass of a hydrogen stage for the same job.”

              Caps added to note the key point.

              He was talking about the advantage of a denser propellant for a first stage not an upper stage.

              • Gary Church

                “-engines 2/3 and tanks 1/2 the mass of a hydrogen stage for the SAME job.”

                It is not the same job. The lower and upper stages are not the same job. The 2/3 and 1/2 are contrived.

                • Joe

                  Yes, but the same job referred was a hydrogen stage to do the first stage job.

                  Take out some of the technical detailed language and the sentence would read:

                  But just a fast figure as I did here suggests that kerosene FIRST STAGES delivering 5,000 m/s …. WILL HAVE engines 2/3 and tanks 1/2 the mass of a hydrogen stage for the same job.”

                  The sentence is information dense, but the above should make its intent clear.

                  • Gary Church

                    Whatever advantage Kerosene has in a lower stage is “trumped” by the advantages of the solid fuel booster in very large vehicles. Which is why they went with it on the shuttle. That has not changed any more than the rocket equation has. ULA is going “smaller” with Methane to try and shave a few percent off the cost of doing business with hydrogen; I consider any move away from hydrogen turbopump-fed engines to be very bad for the future Beyond Earth Orbit- Human Space Flight.

                    The thrust of these various boosters and engines has to go up- not down. The launch vehicle total thrust have to go up by an order of magnitude into the over 20 million pound thrust range if any progress is to be made in space. The reality is we have to go big or we might as well not go. It is like trying to establish routes across the North Atlantic using tree bark canoes. This will take massive governmental resources and that makes the NewSpace libertarian agenda a farce.
                    There is no cheap.

                    As I have stated several times, the ideal lower stage solution is the methane pressure fed booster recovered at sea like the shuttle SRB. The reason such a booster has never been developed is the lack of military R&D to build on to cut costs.

                    • Gary Church

                      I broke my own rule and used an analogy concerning tree bark canoes and I am absolutely certain I will regret it. But I might as well expound on this principle; if you told a primitive tribe with stone tools they would have to dig up huge amounts of rock and burn it to make metal tools and cut down whole forests with these tools to make giant canoes so big they cannot even be dragged up on the beach- and then tell them they would not even be paddled and the wind would blow them to their destinations months away across the ocean- they would not really understand. To them it would be fantastic, outlandish, and a waste of time and effort.

                      It is a similar situation with our tree bark LEO canoes. We will never go anywhere from LEO no matter how many times a week we launch the canoes. It follows that chemical energy is essentially useless for interplanetary travel. However nuclear energy is not appropriate in most of cislunar space due to the Earth’s magnetosphere funneling radioactive byproducts back into the atmosphere. This makes the Moon and lunar orbit the only “shipyard” where we can acquire the water-as-shielding and assemble, test, and launch spaceships.

                      To get the components to our “shipyard” in any reasonable time frame will require much larger launch vehicles than Saturn V if 6 to 8 flights a year is to be utilized. The Super Heavy Lift Vehicle is the most efficient method and making it a wet workshop concept with reusable components if possible is the path to space. Low Earth Orbit is not really space. NewSpace “entrepreneurs” will not be launching 20 million pound plus thrust vehicles or transporting fissionable material to the Moon. Which is why NewSpace advocates react so negatively to the inflexible path.

                    • se jones

                      The market for ULA’s replacement for Atlas V / Delta IV is national security payloads, the occasional planetary probe and GEO comm sats. Grandiose space settlements don’t enter into the equation *at all*.

                      LH2 is difficult and unforgiving to work with for ground crews, but worth it for some upper stages. The mass penalties for the low density LH2 tankage, and the waste of high Isp in the dense lower atmosphere plus gravity losses, has been explained to you previously. Methane makes a good compromise fuel for first stage, with the advantage of the engines being adaptable to use with methane produced on Mars, hence the SpaceX BFR Raptor using CH4.

                      Big solids are expensive to manufacture and placing “loaded ordnance” inside launch facilities is risky (as the Brazilians found out the hard way).
                      Shuttle went with solids to ostensibly save on development costs, but SRB recovery and reuse turned out to be for show, over the life of the program zero money was ever saved. Again, to save up-front costs, SLS will use Shuttle SRBs, but not recover them. The Utah delegation is happy though.

                      Chemical engines are fine for SLS Mars Direct type missions or the SpaceX MCT. If there is return propellant waiting for you at the destination (or you don’t plan on returning) SLS-2 and MCT have plenty of throw weight.

                      If Nuclear Thermal Rockets (NTR) are available (possible if the Russians regain their sanity), using them in LEO is not an issue. The exhaust from a NTR is just hydrogen, there is negligible activation. The tiny amount of tritium in the exhaust would be utterly lost and undetectable from the naturally occurring tritium in the atmosphere. In any case, for some mission models, a chemical LH2 stage is superior to NTR because of the heavy NTR engine kills your mass ratio, it just depends.

                      As for ship yards and canoes and wet workshops every two weeks …er what???
                      You sound like some of the old NSS members in the 1970s. Good luck with that.

                    • Gary Church

                      “-placing “loaded ordnance” inside launch facilities is risky-”

                      No NASA launch facilities in Brazil.

                      “-but worth it for some upper stages-”

                      No….all upper stages. Not some.

                      “-SRB recovery and reuse turned out to be for show,-”

                      Actually I visited the facility where they inspected the steel segments- it was not for show. That was explained to you.

                      “Chemical engines are fine for SLS Mars Direct type missions or the SpaceX MCT.”

                      The cosmic ray rats tell a different story- go ahead and mock that.

                      “If Nuclear Thermal Rockets (NTR) are available (possible if the Russians regain their sanity), using them in LEO is not an issue.”

                      Good luck with that.

                    • se jones

                      In 2003 a Brazilian Space Agency VLS-1 SRB ignited on the pad during launch prep and killed 21 technicians.

                      The nightmare scenario for NASA is an SRB accident in the VAB which would take out the agencies KSC manned program infrastructure and kill potential hundred of workers. The SRB segments have “loaded” stenciled on the side for a reason. On the way from Utah to KSC, the segments aren’t allowed to take the shortest route through Colorado’s Moffat tunnel, because “loaded ordnance” is not allowed in the tunnel.

                      The agency has always wanted to replace SRBs on anything that goes in the VAB, but the money or political hasn’t been there. Yet.

                      So you visited a facility. So what?
                      Fishing out of the Atlantic, washing, shipping, cleaning, X-ray and die penetrate inspection, packing the chutes, and so on, is *extremely* labor intensive. It was clear from the very beginning of the Shuttle program, that re-using the SRBs was for show (aka PR) and made no financial sense, except to the loyal Utah delegation. Hence the “for show”.

                      There are a variety of upper stage designs for different missions. Many missions require an upper stage that with long on-orbit loitering times and multi-restarts (for instance) so the boil-off of an LH2 stage is a problem, as is the expense and hazard of LH2 handling at the pad.

                      Crew radiation doses are a calculated risk that astronauts are willing to accept. There are opportunity costs with any risk reduction, the billions spend on marginal radiation risk mitigation will come from other mission elements and competing social programs. These are complex systems management decisions, nothing in pioneering crewed aerospace is without risk, there are trade-offs.

                      There is always a chance that a future administration will pick a NASA administrator who will champion Nuclear Thermal Rockets. Fundamental research on fuel element design is ongoing a Marshall. But, as is always the case in space flight, higher performance goes toward lower launch mass, rather than faster trip time. A actual NTR engine program will be done in order to reduce the number of SLS launches not to reduce flight time.

                      Again: the exhaust from a NTR is just warm hydrogen, not a plasma, so there is nothing to “get funneled” into the magnetosphere in any case.

                      I bring up the Russians, because their most valuable contribution to an international Mars mission would be the Nuclear Thermal Rocket engines, the Russian public has less fear of nuclear energy than the American public and Russia’s nuclear industry is well suited to NTR development.

                      Yes, good luck to all of us with the Russians.

                    • Gary Church

                      “The SRB segments have “loaded” stenciled on the side for a reason.”

                      Never had an SRB accident in over 30 years of operation.

                      “So you visited a facility. So what?”

                      Over 200 flawless firings in a row- that’s what.

                      “-long on-orbit loitering times and multi-restarts-”

                      Centaur, Delta Cryogenic Second Stage (DCSS).

                      “Crew radiation doses are a calculated risk that astronauts are willing to accept.”

                      It is the elephant in the room; nobody is going to Mars without about a thousand tons of water between them and the heavy nuclei component of galactic cosmic radiation.

                      “-there is nothing to “get funneled” into the magnetosphere-”

                      Playing with nuclear energy in space is not going to happen anywhere near the Earth. Appropriately packaged and launched (SLS/Orion LAS is the only acceptable system)fissionable material will only be assembled and tested outside the magnetosphere. Deal with it.

                      “-their most valuable contribution to an international Mars mission would be the Nuclear Thermal Rocket engines-”

                      NTR’s use a reaction a million times more powerful than chemical rockets with an Isp only a little over twice as high; pathetic. They are far more trouble than they are worth. It is hard enough keeping a chemical rocket engine from melting. Nuclear pulse is the only viable interplanetary propulsion system and that is not going to change for a long time.

                    • se jones

                      You are a pistol, the most amazing things come out of your head.

                      Big solids are expensive and dangerous, that’s why the USAF couldn’t wait to retire the Titan IV.
                      https://youtu.be/nqlgUuYQU30
                      The 21 technicians killed in Brazil plus the crew of Challenger would probably would counted as “accidents” in the last 30 years. Probability of a SRB segment lighting off accidentally in the VAB is low, but not zero, which is why stacking the SRBs is a high-risk, essential personnel operation only.

                      As for upper stages, probably 95%+ of all upper stages ever launched have used either storable liquids (Hydrazine/NTO) or a solid like the ubiquitous the Star 48. Economics matter in the real world. Your decree about LH2 is like saying all cars *must* have a $55,000 supercharged, nitromethane burning, billet big block, drag racing engine.

                      Your ideas about the magnetosphere and nuclear thermal engines is most interesting.
                      There’s a *lot* of bad science reporting about cosmic radiation, I should cut you a break, but you claim to be such an expert about everything…I don’t get it.
                      What do you think the magnetosphere is? Do you think is “shields” the earth from cosmic rays or something?
                      You are aware, for instance, that the ISS hosts the Alpha Magnetic Spectrometer which “sees” high energy positrons coming from the distant universe? Soon, the AMS will be joined in the ISS by the Extreme Universe Space Observatory (my group will be using the EUSO to look at gamma rays coming UP from certain thunder storms). Just this week, the (cosmic ray) Telescope Array in Utah was in the news because Japan as started a $3.7 million project to quadruple the size of Array. And last month, the new Miracle Array High Altitude Cerenkov Array opened for business in Mexico. What do you think these telescopes are looking at if the magnetosphere “shields” the earth? Hell, you can watch muons from space with a homemade cloud chamber, millions are going into and through you right now, even with earth’s massive atmosphere shielding you.
                      The magnetosphere diffuses low energy plasma from the sun, which has helped maintain the chemistry of the atmosphere over geologic time, but that’s it. That’s why ISS astronauts receive a sizable fraction of the dose that Mars bound astronauts would receive, we have a cumulative total man-month experience with cosmic ray exposure, well within the magnitude of Mars explorers.

                      Nuclear thermal engines were thoroughly developed in the 1960s to 1970s, when the NERVA project was cancelled in 1972, the AEC & NASA were ready to build flight hardware. Unfortunately, with the Saturn V cancelled the NERVA had no mission or launch vehicle.

                      The higher Isp of NTR is significant and can cut the launch mass of Mars mission nearly in half. Even better, is the LOX Augmented Nuclear Thermal Engine. Lox augmentation takes advantage of the Oberth effect to boost performance along with the structural savings from the smaller LOX tanks which are jettisoned during TMI before switching to pure NTR.

                      Why would you worry about a NTR “melting”? The nozzle is regeneratively cooled like any liquid engine, and the thrust comes from passing the working fluid through the reactor core channels, the working fluid (usually hydrogen) carries away the heat, which is the point. It’s proven technology.

                      You should be all over the LOX augmented NTR because it’s a natural for using lunar derived O2. Getting the O2 from lunar ice is fine, but we know for sure how to “mine” oxygen from common lunar regolith.

                      By the way, the P&W Triton nuclear engine core contains fewer curies of radioactive material than RTGs, which we’ve been launching for decades. Only eco nuts get all worked up over RTGs, I guess you agree with them?

                      The beauty of NTRs is that they are just a “steam kettle”. With the right fuel cladding, a NTR can use most any fluid for reaction mass, which will come in handy in the more distant future when we can mine water & CO2 in the solar system.

                      The big road block to nuclear rockets and opening the solar system is the public’s ignorance.
                      You are not helping.

                      Pick up a book, learn the basics, so something positive for a change.

                    • Gary Church

                      “-you claim to be such an expert about everything…I don’t get it.”

                      “Pick up a book, learn the basics, so something positive for a change.”

                      Uh-huh. You don’t get it- you need to follow your own advice.

                    • Joe

                      Hi Gary,

                      A little more detailed response might be in order.

                      For example Mr. Jones suggested discussing the Liquid Oxygen Augmented Nuclear Thermal Rocket (LANTR):

                      “You should be all over the LOX augmented NTR because it’s a natural for using lunar derived O2. Getting the O2 from lunar ice is fine, but we know for sure how to “mine” oxygen from common lunar regolith.”

                      In the past you have expressed admiration for the LUNOX concept, but it also integrated use of the LANTR.

                      http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19960002346.pdf

                      So, specifically, what is you opinion of use of LANTR to enhance the development of Lunar Resources and Cis-Lunar Space; as this is a prerequisite to any of the further plans you say you support.

                    • Gary Church

                      Hi Joe,

                      You have been reading my comments for years on Dr. Spudis’ site; I say again, NTR’s use a reaction a million times more powerful than chemical rockets with an Isp only a little over twice as high; pathetic. They are far more trouble than they are worth. It is hard enough keeping a chemical rocket engine from melting. Nuclear pulse is the only viable interplanetary propulsion system and that is not going to change for a long time.

                      In my view there are certain key points that cannot be ignored concerning Human Space Flight. As I stated, we have corresponded for a couple years on Dr. Spudis’ site, you are aware of those points, so I am puzzled by your query- unless your recent dislike for me is driving it. Whatever.

                      Here is a review:
                      1. LEO is not really space- it is a dead end.

                      2. Inferior lift rockets and propellent depots are a dead end.

                      3. Mars is gimmick- a P.R. device, and is also….a dead end. O’Neill was correct and mega-structures like Bernal Spheres are the only solution to a permanent human presence in space.

                      4. Cosmic radiation means 500 tons of water shielding for a small capsule- the “Parker minimum.” And since a great deal more living space is required on long duration missions in practical terms this means thousands of tons of water- massive radiation shields.

                      5. There is no practical system of pushing such shields around the solar system except bombs.

                      6. The only place to acquire the water shielding, assemble, test, and launch nuclear missions, is the Moon. The Moon is the next step, not LEO, not Mars, and Ayn Rand libertarians and private investment is not going to make it happen.

                      7. The only practical method of establishing such a cislunar infrastructure is with Super Heavy Lift Vehicles, wet workshops, and massive governmental resources.

                      All these points are the direct opposites of those found in the NewSpace business plan and just about everything the public has been fed about our supposed space program.

                      I could go on about GEO von Braun wheels and then Space Solar Power but what’s the point? The people replying to me are mostly obnoxious naysayers, rancorous conservatives, or NewSpace sycophants. They just want a target to shoot at.

                    • Joe

                      Gary Church said June 6, 2015 at 9:11 am.

                      Yes I am very aware of all those positions of yours from your many postings here.

                      The question asked was – “So, specifically, what is you opinion of use of LANTR to enhance the development of Lunar Resources and Cis-Lunar Space; as this is a prerequisite to any of the further plans you say you support.”

                      A link to a specific NASA research on the subject was provided. If you did not look at the provided document, it was very positive towards the use of NTR (specifically LANTR) for Cis-Lunar Space operations.

                      While you restated all of your (by now well known to anyone reading these comments sections)positions you did not address the question actually asked.

                      I will try one more time, then (if you do not address the question) assume you simply refuse to do so.

                      Do you have any specific technical rebuttals to NASA Technical Memorandum 107093 (at the link)? If so are you willing to share them?

                    • Gary Church

                      I will try one more time, NTR’s use a reaction a million times more powerful than chemical rockets with an Isp only a little over twice as high; pathetic. They are far more trouble than they are worth. It is hard enough keeping a chemical rocket engine from melting. Nuclear pulse is the only viable interplanetary propulsion system and that is not going to change for a long time.

                      My opinion is obviously that NTR’s are worthless. That is what you get and you can take it or leave it Joe. I don’t care which.

                    • Joe

                      Gary Church June 6, 2015 at 3:34 pm

                      “That is what you get and you can take it…”

                      Since you once again refuse to address the any of the specifics of NASA Technical Memorandum 107093, I will leave it.

                      Have a nice weekend

                    • John hare

                      So having made up your mind, nothing is worth considering in terms of alternatives. That attitude requires you to be right 100 percent of the time. It doesn’t work like that in business, politics, war, and for certain not on space development. All seven of your points are either dead wrong, or disputable by informed investigaters. It is a shame that someone of such strong opinions cannot be bothered to study his subject.

                    • Gary Church

                      whatever you say John

        • Gary Church

          “Many others do not share your opinion-”

          Yes to the king of obvious.

          “-do have moving parts despite your claim contrary.” Yes, when I was writing the comment it crossed my mind I better qualify that because someone would do exactly what you did.

      • Well, as a once-upon-a-time non-propulsion engineer–is anyone here a propulsion person?–I doubt the engineering is that cut and dry. And I know of a few propulsion guys who in working with RP/LOX today seem to disagree that kerosene is obsolete.

        • john hare

          I’ve been through enough books and other references to know that propulsion is a huge field. My studying several aspects of it doesn’t make me a propulsion guy. I’ve done a bit of concept work that might do some good eventually. But fully knowledgeable propulsion guy, no. I have a few answers, but no field experience, which also disqualifies me from that title.

          • Gary Church

            “I have a few answers, but no field experience, which also disqualifies me from that title.”

            This is a public discussion forum for space advocates- you are only disqualifying yourself John. You are certainly not going to hold others to those standards here.

          • Gary Church

            “I have a few answers, but no field experience, which also disqualifies me from that title.”

            This is a public discussion forum for space advocates- you are only disqualifying yourself John. You are certainly not going to hold others to those standards here.

            • John hare

              My throwing numbers out there could be construed as trying to pass myself off as an expert. Having knowledge of the field does not make me one and is an insult to those that are.

              • Joe

                Understood John, but Mr. Church seems more concerned that you are trying to hold him to such a standard and is rejecting that concept.

                • john hare

                  Thanks Joe. I’m still not sure how explaining my lack of credentials is offensive. I know what I am talking about most of the time and feel that serious people do the same. I also feel that people should know that I am not a credentialed expert so they know how much weight to put on my comments. Serious people also try not to oversell themselves. That’s what I was trying for.

                • Gary Church

                  “-Mr. Church seems more concerned that you are trying to hold him to such a standard-”

                  Don’t care. But you do.

                  • Joe

                    Gary Church
                    June 3, 2015 at 6:03 pm · Reply

                    “Don’t care.”

                    Then why did you double post complaining about it.

                    (1) Gary Church
                    June 3, 2015 at 11:09 am · Reply

                    (2) Gary Church
                    June 3, 2015 at 11:10 am · Reply

                    “But you do.”

                    I assume that statement means something to you, but I have no idea what it is supposed to mean.

              • Gary Church

                The only people cred bragging and trying to pass themselves off as experts are those trying to intimidate and shut down others from expressing their views. The rest of us are writing what we want.

  • […] This article leaves me speechless. How could anyone capable of putting words together in a sentence about space hardware put forth a premise that is “not even wrong”. It is not even from the same reality most of us exist in. […]

  • SpaceX Merlin engines?

    • Tim Andrews

      The American made Merlin 1D is a gas generator cycle design, which is functionally less advanced than the stage combustion design used by the Russian made RD-180. It’s akin to arguing about leadership of internal combustion engine manufacturers based on whether they use carburetors or fuel-injection. For SpaceX, there are definite advantages to the gas generator – lower cost (time and money) development, and if one is looking toward re-used there are advantages to minimizing complexity.

  • Jeff Wright

    I want to see Dynetics F-1 concept supported by the USAF

    • Yeah, I too love the mighty Pyrios!

      A family of F1B powered boosters, one for SLS “stage zero” and a derivative for DoD (and maybe competition for Falcon Heavy) would have killed two birds with one stone.
      The twin F1B powered stand-alone would have been overpowered for most AF launches, but better to have power to spare than not enough.

      It’s a pity, in life timing is everything. Had Putin’s European expansion, followed by our push to end RD-180 dependence, happened sooner, the mighty Pyrios may have lived.

      Unfortunately, I just don’t see the agency re-opening a competition for SLS boosters, ATK has too much pull and NASA will need the money for upper stage work.

    • Gary Church

      A big dumb reusable pressure fed booster- a “methane monster” of over 5 million pounds thrust (probably twin thrust bells on each booster of 3 or 4 million pounds of thrust each)is what is needed. Parachute them into the ocean like the shuttle SRB’s. This is the reusable component that a Human Space Flight – Beyond Earth Orbit program requires to accomplish anything worthwhile in a reasonable amount of time. Some of the original shuttle designs specified such a booster- with waterproof doors- but it would have cost far more to develop than the SRB’s which already had most of the R&D paid for by the military. Going cheap always ends up costing more in the end.

      The ideal launch vehicle would use a pair of such boosters and with a hydrogen core have a lift-off thrust of well over 20 million pounds. The core would be a wet workshop and boost straight to the Moon. At some point after escape velocity the engine package would separate, fly all the way around the Moon on a free return and back to Earth and with a heat shield, waterproofing scheme, and parachute, splashdown and be recovered for reuse- at least the turbopump/s anyway.

      The core payload would be a robot methane lander with a zero boil off system (ULA is developing a piston engine to do this) and the lander ascent engine would be powerful enough to insert the workshop into a lunar polar “frozen” orbit. The lander would then separate and using a pair or more of smaller variable thrust descent engines land on ice deposits for ISRU. Using the volatiles trapped in lunar ice the lander would convert some of this water into methane and oxygen and using the original powerful main engine ascend back into orbit and transfer the water to the wet workshop as radiation shielding. The lander would then separate and repeat the process till it wears out.

      With these semi-expendable robot landers filling the radiation shields of wet workshops within a few months these empty upper stages would have full cosmic ray water shields proof against any possible solar storm and be ready for astronauts. Within a few years with 6 to 8 launches a year there would be dozens of astronauts in lunar orbit assembling these workshops into larger configurations as space stations and spaceships. With a pair of workshops spinning on a tether system the astronauts would have Earth gravity and near sea level radiation levels and would thus suffer no health hazards and could stay as long a desired.

      • John hare

        I ran the number on your LV and came up with well under 100 tons inTLI that wasn’t tanks or engines. Deduct the heatshield for engine recover and add realistic required hardware and real payload seems to go negative. I was trying for fairly generous assumptions down the line and still couldn’t make it close technically. OTOH you would have 12,000 cubic meters of tank in TLI.

        • Joe

          You really need to stop running numbers when somebody free styles a design.

          It’s a real bummer. 🙂

          • john hare

            My apologies. The places I usually post tend toward the, “If you can’t say it with numbers, it’s opinion, not fact.” attitude. It really makes it humiliating when you are busted for mixing them up. 🙂 I got hammered pretty good one time for (massively) overestimating the ability to use the moon for a gravity turn.

        • Gary Church

          “-real payload seems to go negative.”

          Not as negative as you and your smiley face friend. A 20 million pound thrust launch vehicle cannot send anything to the Moon. Right. Thanks for “running those numbers.”

          • i think the better reply would have been to simply ask him for his numbers.

            • Gary Church

              Yes, and the smiley faces and mocking sarcasm are just fine. Who wants to comment on these forums when they get this kind of reply? Nobody.

              • Gary, you’ve stoked that fire just as much as anyone. Truman’s ol’ Kitchen analogy applies here.

                But reading the comments here, I don’t see the type of activity you’re talking about.

            • John hare

              Other than a couple of big dumb boosters, he was suggesting Single Stage To Trans Lunar injection. With losses, 12,400 m/s Delta V. Tough gig without staging.

              • Gary Church

                “Tough gig without staging.”

                Yes, I understand how the rocket equation works.

                If the big dumb boosters are cross-feeding LOX the first couple minutes it helps- the same trick SpaceX is hoping will work for their faux heavy. If the cores stage sheds all it’s engines except one for the final 30% of the propellent burn it helps, or some form of external drop tanks for the core stage LOX would help.

                And if the desired wet workshop and robot lander cannot be had then yes, another hydrogen stage would be required. External tanks are the same reasoning that led to the ET on the shuttle being the only expendable component but unfortunately with the wet workshop concept it threw away the most important part of the vehicle. For Human Space Flight the humans need someplace to live and the wet workshop makes the stage the main part of the payload as the crew compartment component of space stations and spaceships.

                Which is why the shuttle was such a bizarre bassackwards design- instead of going deeper into space it retreated into LEO, instead of sending as much payload as possible into space it brought most of what it lifted right back to Earth. Instead of splashing down on a water world with a mass penalty of a few thousand pounds of parachutes, floats, etc. for crew return it sacrificed most of the lift of a Saturn V class vehicle on wings, landing gear, airframe, etc.

                As for reusability- if a booster or engine comes close to breaking even like the shuttle SRB then it is worth it because it allows for inspection and warning of any problems. This was the reason for over 200 in a row flawless shuttle SRB firings. Reusing the core engines may never be worth it- which is where the RS-68 came from. But it is worth a try.

                Reusing kerosene or methane turbopumps might never be worth the trouble while pressure feds would probably be superior to solid fuel SRBs and actually break even or better. Reusing upper stage hydrogen turbopumps with a lunar free return splashdown is the big challenge as it would complete a trinity with the big dumb booster and wet workshop. Such a Super Heavy Lift Beyond Earth Orbit system would be far more “game-changing” than landing back inferior lift rocket stages with clusters of low thrust kerosene engines.

                I would be a manic SpaceX fan if their building blocks had been a big dumb methane booster and smaller hydrogen upper stage engine like the BE-3. But the Merlin determined from the start they would have limited capability and most of the design decisions they have made have limited them even more. As it is the NewSpace business business plan of taking some lego blocks and a couple gallons of gas at a time into the dead end of LEO is the worst possible path. That is all I will say about that.

                • Gary Church

                  “-the shuttle was such a bizarre bassackwards design-”

                  The best explanations for this only add more bizarro fruit to the cocktail- saying the shuttle was a case of “going cheap” generates a predictable reaction when it cost almost as much as the Saturn V it replaced. Most of the shuttle design features also fit well with the rumor the Air Force wanted to kidnap Russian spy satellites with it. Just crazy enough to be true.

  • ” Yes, when I was writing the comment it crossed my mind I better qualify that because someone would do exactly what you did.”

    Factual accuracy is the first casualty of sweeping generalizations (which of course is yet another logical fallacy).

  • Gary Church

    “The SRB segments have “loaded” stenciled on the side for a reason.”

    Never had an SRB accident in over 30 years of operation.

    “So you visited a facility. So what?”

    Over 200 flawless firings in a row- that’s what.

    “-long on-orbit loitering times and multi-restarts-”

    Centaur, Delta Cryogenic Second Stage (DCSS).

    “Crew radiation doses are a calculated risk that astronauts are willing to accept.”

    It is the elephant in the room; nobody is going to Mars without about a thousand tons of water between them and the heavy nuclei component of galactic cosmic radiation.

    “-there is nothing to “get funneled” into the magnetosphere-”

    Playing with nuclear energy in space is not going to happen anywhere near the Earth. Appropriately packaged and launched (SLS/Orion LAS is the only acceptable system)fissionable material will only be assembled and tested outside the magnetosphere. Deal with it.

    “-their most valuable contribution to an international Mars mission would be the Nuclear Thermal Rocket engines-”

    NTR’s use a reaction a million times more powerful than chemical rockets with an Isp only a little over twice as high; pathetic. They are far more trouble than they are worth. It is hard enough keeping a chemical rocket engine from melting. Nuclear pulse is the only viable interplanetary propulsion system and that is not going to change for a long time.

  • se jones, please stop clouding the issue with easily verifiable facts that readily disprove most of Mr. Church’s claims 😉 And implying that you have any expertise in any space-related subject will not impress him and only further provoke him.

    BTW, as a physicist I am certainly impressed with your involvement in EUSO. I am currently involved in a NASA-approved project for the ISS crew to secure photos of tropical cyclones to support work my group is doing on improving forecasting of these storms using only remote sensing data. While it is nice to see the ISS being used for some good science, both these projects are small pieces of evidence that counter Mr. Chruch’s often-made claim that LEO is a dead end and that everything can be done from balloons or from GEO and beyond.

  • Gary Church

    “-you claim to be such an expert about everything…I don’t get it.”

    “Pick up a book, learn the basics, so something positive for a change.”

    Uh-huh. You don’t get it- you need to follow your own advice.

  • Gary Church

    “-you claim to be such an expert about everything…I don’t get it.”

    “Pick up a book, learn the basics, so something positive for a change.”

    Uh-huh. You don’t get it- you need to follow your own advice.

  • Gary, you also failed to address all of the other issues raised by Mr. Jones like the documented safety issues with large solid rocket motors (including several Titan III failures, the Challenger accident, etc.), the fact that while liquid hydrogen/LOX certainly has performance advantages there are other factors that go into designing upper stages that make other propellants more attractive for some designs (hence the propensity of solid rocket motors like Star 48 and the IUS as well as those using storable propellants that have been in use for the past four decades-plus), etc. etc… basically, Mr. Jones completely tore apart all of your arguments with easily verifiable facts known to many space enthusiasts and you failed to address any of them. Are you conceding you were completely wrong???

  • Gary Church

    Hi Joe,

    You have been reading my comments for years on Dr. Spudis’ site; I say again, NTR’s use a reaction a million times more powerful than chemical rockets with an Isp only a little over twice as high; pathetic. They are far more trouble than they are worth. It is hard enough keeping a chemical rocket engine from melting. Nuclear pulse is the only viable interplanetary propulsion system and that is not going to change for a long time.

    In my view there are certain key points that cannot be ignored concerning Human Space Flight. As I stated, we have corresponded for a couple years on Dr. Spudis’ site, you are aware of those points, so I am puzzled by your query- unless your recent dislike for me is driving it. Whatever.

    Here is a review:
    1. LEO is not really space- it is a dead end.

    2. Inferior lift rockets and propellent depots are a dead end.

    3. Mars is gimmick- a P.R. device, and is also….a dead end. O’Neill was correct and mega-structures like Bernal Spheres are the only solution to a permanent human presence in space.

    4. Cosmic radiation means 500 tons of water shielding for a small capsule- the “Parker minimum.” And since a great deal more living space is required on long duration missions in practical terms this means thousands of tons of water- massive radiation shields.

    5. There is no practical system of pushing such shields around the solar system except bombs.

    6. The only place to acquire the water shielding, assemble, test, and launch nuclear missions, is the Moon. The Moon is the next step, not LEO, not Mars, and Ayn Rand libertarians and private investment is not going to make it happen.

    7. The only practical method of establishing such a cislunar infrastructure is with Super Heavy Lift Vehicles, wet workshops, and massive governmental resources.

    All these points are the direct opposites of those found in the NewSpace business plan and just about everything the public has been fed about our supposed space program.

    I could go on about GEO von Braun wheels and then Space Solar Power but what’s the point? The people replying to me are mostly obnoxious naysayers, rancorous conservatives, or NewSpace sycophants. They just want a target to shoot at.

  • James

    Many ideas for exploring and developing the Solar System are workable. Effective shielding from GCRs will be a critical issue for long-term human missions.

    However, the short-term showstopper issue for beyond LEO human missions seems to be money.

    For the next few decades, the SLS and international Orion could be quite useful in helping us find and use Lunar resources to develop the Moon and the rest of cislunar space.

    Who is going to build the various types of needed Landers?

    The selection of Kero/LOX, Kero with nano-particles of aluminum/H2O2, methane/LOX, H2/LOX, nuclear, or whatever else that might be reliable and useful for rocket engines will be determined by those companies or nations that build the Lunar Landers.

    The Moon Express MX-1 Lunar Lander’s main rocket engine will burn Kero/H2O2.

    See: http://www.gizmag.com/moon-express-mx-1-lunar-lander/30050/

  • James

    Not everyone is impressed with using Methane/LOX rocket engines for boosters.

    “The payload performances of the reusable kerosene and methane booster are therefore almost identical with some edge for kerosene. In view of the increased size and dry mass of a reusable methane booster stage, one can expect a cost disadvantage for CH4 from a launch vehicle system level point of view.”

    From: Comparative Study of Kerosene and Methane Propellant Engines for Reusable Liquid Booster Stages By Holger Burkhardt, Martin Sippel, Armin Herbertz, and Josef Klevanski 4th International Conference on Launcher Technology “Space Launcher Liquid Propulsion” 3-6 December 2002 – Liège (Belgium)

    Many ideas for exploring and developing the Solar System are workable. Effective shielding from GCRs will be a critical issue for long-term human missions.

    For the next few decades, the SLS and international Orion could be quite useful in helping us find and use Lunar resources to develop the Moon and the rest of cislunar space.

    Who is going to build the various types of needed Landers?

    The selection of Methane/LOX, Kero/LOX, Kero and nano-particles of Aluminum/H2O2, H2/LOX, nuclear options, or whatever else that might be useful for rocket engines will be determined by those companies or nations that build the Lunar Landers.

    The Moon Express MX-1 Lander’s main rocket engine will burn Kero/H2O2.

    See: http://www.gizmag.com/moon-express-mx-1-lunar-lander/30050/