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
Feb 182018

A few decades before the “X-Wing” configuration gained a measure of popularity, Hughes Tool Company made a detailed study of a somewhat similar concept, the “rotor/wing.” This was a three-bladed helicopter rotor attached to a large central lifting surface, either a circular disk or a triangular structure. The rotor was not turned the conventional way with a turbine engine turning a drive shaft, but instead the engine exhaust was ducted through the center and then out to nozzles at the tips of the rotors. Jet thrust would spin the rotors without transmitting torque to the rest of the vehicles; as a consequence only a small tail rotor would be needed, just powerful enough to orient the craft at low airspeeds.

A few configurations were produced, most of which looking much the same. Probably the most well known configuration was shown in US VTOL Projects 01. Shown below is a lesser-known configuration designed for anti-submarine use. Normally the configurations included the turbojet engines within the upper fuselage, close to the hub of the rotor, but this one rather bizarrely put the engines on the tail. No obvious means of ducting the exhaust to the rotor is evident, so presumably a third (or even fourth) engine was tucked into the fuselage somewhere.


 Posted by at 2:21 am
Feb 132018

Now available: two new US Aerospace Projects issues. Cover art was provided by Rob Parthoens, www.baroba.be

US VTOL Projects #2

US VTOL Projects #2 is now available (see HERE for the entire series). Issue #2 includes:

  • SOS Interceptor: A US Navy Mach 3 aircraft with jettisonable wings
  • Lockheed GL-224-3: A small battlefield surveillance and ground attack plane
  • Phalanx Dragon MP-18: An unconventional  small civilian transport
  • Lockheed L-161-1: An early concept for a variable geometry roadable helicopter
  • GE Supersonic V/STOL: A supersonic strike fighter with flip-out lift fans
  • Convair ANP-VTOL: A nuclear-powered ground-effect craft of the Navy of unusual configuration
  • Piasecki 16H-3: A compound helicopter for high speed passenger transport
  • Boeing Vertol Model 147: A tilt-wing close support fire support design for the US Army

USVP #2 can be downloaded as a PDF file for only $4:


US Research & Recon Projects #2

US Research & Recon Projects #2 is now available (see HERE for the entire series). Issue #2 includes:

  • Lockheed A-1: The first true design leading to the SR-71
  • Bell MX-2147 Model 105: The high altitude “X-16”
  • Boeing/CRC/AMROC X-34 Reference Configuration: A reusable launcher test vehicle
  • Martin Model 159: A scout/observation float plane
  • NASA-Langley Low-Boom Demonstrator: a recent design to demonstrate quiet SST tech
  • McDonnell-Douglas DC-9 Super 80 Propfan Configuration 1: A fuel efficient transport demo
  • Convair “HAZEL” MC-10: An inflatable Mach 3 plane for the Navy
  • Republic Manned Hypersonic Reconnaissance Vehicle: an early scramjet concept


USRP #2 can be downloaded as a PDF file for only $4:


 Posted by at 12:53 pm