Mar 092018

Advanced “space guns,” typically lasers, railguns, coilguns, neutral particle beams and the like, have a problem: power. Nuclear reactors and solar panels can provide power for years at a time, but generally their steady-state power output is only a tiny fraction of the instantaneous power needed when the gun goes off. So to run a weapon that needs many gigawatts for a fraction of a second with a powerplant that produces kilowatts, you need an energy storage system that can convert that energy into power on a moments notice. Things like batteries are great in principle, but their weight is vast and their ability to release power at the high levels needed is generally poor.

Often this has resulted in space weapons that use chemical reactions to provide the power needed. This has meant that the total number of shots that can be fired is strictly limited.

In the 1980’s during the SDI heyday, Westinghouse looked at an alternate approach: rotating hoops. Giant wheels made of advanced composite materials would be spun up over time by a low-power system such as a nuclear reactor, and when needed these flywheels would be electromagnetically braked to generate vast amounts of power as the wheels ground to a  halt. The system could be “reloaded” by slowly spinning the wheels up again… assuming the system hadn’t torn itself part.

The weapon shown below is probably largely notional, no masses or dimensions were given. But based on a smaller terrestrial unit (with ten hoops, each 14.5 meters diameter, massing 140,000 kg each, spinning at 1800 RPM to deliver a total of 1 gigawatt for 10 minutes to power anti-missile lasers and such), this can be assumed to be a fairly *vast* construction, far heavier than anything mankind has so far launched into orbit. Obviously such a thing would be impossible to launch as a unit; it would be assembled in space using spools of fibers wound in place. Presumably the weapon itself would be at least somewhat aimable independent of the flywheels… slewing *them* about to aim at a moving target would seem to be an exercise in futility.

This came from the paper “Rotating Hoop, Pulsed-Energy Converter” contained in “Transactions of the Fifth Symposium on Space Nuclear Power Systems.” A PDF of that can be downloaded if you go HERE and click the “PDF” button.

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 Posted by at 4:23 am
Feb 192018

The NERVA nuclear rocket, studied throughout the sixties into the early 1970’s, would have been a great way to propel spacecraft. But a nuclear rocket is not the same sort of reactor as is generally designed for use in space to generate electrical power. A NERVA can produce *gigawatts* of thermal energy, energy which is carried away with the high mass flow rate of the hydrogen propellant. Power reactors, on the other hand, are generally designed for several orders of magnitude lower thermal power… a few thermal megawatts, perhaps, to produce a few hundred kilowatts of electricity.

However, the fact remains that a nuclear rocket *is* a nuclear reactor. For most missions it would burn for a few minutes, at most perhaps  few hours, out of a mission lasting perhaps years. It is thus a bit of a shame to waste all that potential. So over the decades many studies have been made for using a nuclear rocket as a power generator .

One such study was reported by Aerojet in 1970. The abstract is HERE, the direct PDF download if HERE.

In this study, the NERVA would pump out 1,500 thermal megawatts during the propulsion phase(producing 75,000 pounds of thrust), dropping to 250 to 505 thermal kilowatts during the power generation phase, enough to create 25 kilowatts of electricity. This would be a very low-power, low-temperature use of the reactor, reducing system efficiency… but still, making use of a reactor that was already there, and not noticeably using up the fission fuel in the reactor. The reactor would be run at very lower power levels and hydrogen would flow through a closed loop built into the reactor; the warmed gaseous hydrogen would flow through a turbogenerator to create electricity; the warm hydrogen would then pass through a radiator built on the outer surface of the hydrogen tank itself.

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 Posted by at 3:27 am
Jan 092018

The Curtiss-Wright X-19 was a reasonably successful experimental tilt-prop VTOL aircraft from the first half of the 1960’s. Two aircraft were built; one crashed, one is at the USAF Museum in Dayton (I believe it’s in a restoration facility). The Defense Technical Information Center has two CW documents in PDF format that cover the technology of the X-19 in some detail:





One of the documents includes a fold-out three-view diagram of the X-19, scanned in glorious Extra No color two-bit black and white as two separate pages. I’ve stitched them back together and tried to make the diagram look reasonably good; I’ve uploaded the full-rez result of my effort to the 2018-0 APR Extras folder on Dropbox, available to all APR patrons at the $4 level and higher.

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 Posted by at 12:04 am
Dec 202017

Mobile energy depot feasibility study: summary report


Declassified 28 Aug 1973. Various methods of producing and using nuclear power for military land vehicles and other military equipment were investigated and evaluated. A nuclear-powered mobile energy depot (MED) would move with advancing armies and produce vehicle fuels from materials readily available in the field. This would make mechanized units independent of external fuel supplies for extended periods, and permit them to move quickly and easily to areas impossible for units that depend on the customary fuel supply lines. Many possible MED systems were evaluated on the basis of energy sources, fuel manufacturing (by both conventional and chemonuclear processes), fuel storage and transportation, and fuel utilization in both present-day internal-combustion engines and power units of the future (i.e., fuel cells). The applications of more than a dozen MED systems to vehicular propulsion were studied.

The report can be downloaded directly from HERE.

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 Posted by at 10:15 am
Aug 132017

As a followup to the photos of the H-33 display model, here’s a Grumman report from July, 1971, giving a pretty good and well illustrated description of the H-33 orbiter.

The abstract on NTRS can be seen HERE.

The PDF file can be directly downloaded here:

Alternate space shuttle concepts study. Part 2: Technical summary. Volume 2: Orbiter definition


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 Posted by at 2:23 am
Jul 142017

A 1972 Teledyne Ryan report on modifying their supersonic BQM-34E Firebee II target drone into RPV’s for testing new aerodynamics, wings and area-rule add-ons and the like. Numerous diagrams are included.

Here’s the link to the NTRS abstract.

Here’s the direct link to the PDF.



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 Posted by at 11:48 pm
Jul 112017

Seems I’ve been a wee bit lax  on the PDF Reviews I will attempt to rectify that in the future.

Here is a Air Force conference paper from May, 1964, describing the X-20 Dyna Soar program and vehicle. At this point the program had been cancelled for some months; the configuration shown in the paper was essentially the final design. It’s a decent overall view of the Dyna Soar.

Here’s the link to the abstract:

The X-20 (Dyna-Soar) Progress Report

Here’s a link directly to the PDF.


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 Posted by at 11:35 pm
Jun 182017

Here’s an interesting one: a detailed large-format diagram of the US Space Shuttle orbiter… as drawn up by Soviet draftsmen in 1976. Interestingly, the top view includes, in red, the basic outline of the Soviet “Buran” shuttle orbiter. A surprisingly high-rez version of this diagram can be FOUND HERE.

The diagram is not entirely accurate, especially with regards to the OMS pod. The rear end of the pod in the side view is distinctly inaccurate. But note the faint lines just ahead of the OMS pods in the top and side views. One of the last noticeable changes to the Orbiters configuration was the change to the forward end of the OMS pod; originally, the pods continued forward onto the cargo bay doors. This continuation was just an aerodynamic fairing; all the equipment an tanks were in the pod aft of the doors.


 Posted by at 2:12 am
Feb 102017

NASA has just released a report on a Europa lander mission. I haven’t read all the way through it (in fact, I’ve just glanced through it), but it seems fairly extensive. The lander design itself seems pretty preliminary. It also looks like a walking “rover,” but the legs are just long in order to allow the lander to safely come to rest on whatever terrain it happens to land on.

The lander would have instruments meant to look for the signs of life. Pretty obviously, the chances of life appearing *anywhere* near the surface of Europa are as close to zero as you can get. However, assuming that many, many kilometers below there is a liquid water ocean, and assuming that there is recognizable life swimming or floating around in the water, chances are fairly good that bits of it, everything from biochemicals on up to actual critters, would get trapped in the ice. Over extremely long periods of time the cold, icy equivalent of geological processes might drag that stuff up to the surface, where it might be detectable.

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You can download the report here:

Europa Lander Science Definition Team Report

Some of the illustrations:

Europa Lander Image1 Europa Lander Image2 Europa Lander Image3 Europa Lander Image4 Europa Lander Image5 Europa Lander Image6


 Posted by at 8:49 pm
Nov 242016

In 1965, the US Army briefly examined a need they didn’t know they had: firearms for use in space and on the Moon. The US Army Weapons Command in Rock Island, Illinois, put out a brochure detailing some ideas for lunar weapons… “The Meanderings of a Weapon Oriented Mind When Applied in a Vacuum Such as on the Moon.” While not a detailed engineering study, it nevertheless provides and interesting look at the sort of weapons that might be developed for use in a low gravity space environment.


Conventional firearms would work just fine in space… at least for a while. A vacuum would cause most lubricants to outgas and turn to waxy solids or hard rubber-like crud. The extreme differences in temperatures between sunlit and shaded would cause many metals to warp and mechanisms to seize up. And there’s always the possibility of vacuum welding, where two similar metals will simply stick together, fusing into one. And recoil that gives a shooter a good kick on Earth might knock them over on the Moon, or send them tumbling in freefall. The authors described these problems and pointed out potential solutions. Additionally, they provided a number of notional concepts for hand-held weapons, ranging from modifications to the normal sort of firearm, to guns powered by springs (with, it must be said, rather optimistic muzzle velocities) to gas-guns and handheld mini-rocket launchers. It’s odd that the Gyrojet was not included. A laser weapon is said to probably be just the thing, but development of such a thing would take 20 years. A man-portable laser weapon capable of doing useful damage in a  combat situation remains sadly unavailable.

Note that the weapons have quite unconventional ergonomics. Some don’t even have proper pistol grips; those that do have triggers roughly the full length of the grip. This is so that a space-suited hand can squeeze the trigger, something very difficult for a conventional single-finger trigger.


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The brochure ends with several pages of useful math, providing calculations for ballistic range in other gravity fields, penetration capabilities and muzzle velocities and gas pressures.

The report can be found here:

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 Posted by at 2:43 am