Machinery/Automation

Miniature Blimps for Surveillance and Collection of Samples These robots could follow complex three-dimensional trajectories through buildings. NASA’s Jet Propulsion Laboratory, Pasadena, California

Miniature blimps are under develop- structures on Earth. The widely per- 1.2 kg. It can be filled in 30 seconds ment as robots for use in exploring the ceived need for means to thwart attacks from the small bottle shown on the thick, cold, nitrogen atmosphere of Sat- on buildings and to mitigate the effects table in the figure. This blimp also op- urn’s moon, Titan. Similar blimps can of such attacks has prompted considera- erates under radio control and carries a also be used for surveillance and collec- tion of the use of robots. Relative to video camera. This blimp has been tion of biochemical samples in build- “rover”-type (wheeled) robots that have equipped with an ultralight (170 g) au- ings, caves, subways, and other, similar been considered for such uses, minia- tomatic pilot manufactured commer- ture blimps offer the advantage of abil- cially for radio-controlled small air- ity to move through the air in any direc- planes. This autopilot enables the tion and, hence, to perform tasks that control system of the blimp to utilize are difficult or impossible for wheeled the Global Positioning System in fol- robots, including climbing stairs and lowing a trajectory through as many as looking through windows. In addition, 60 different waypoints. This autopilot miniature blimps are expected to have also utilizes ultrasound for precise mea- greater range and to cost less, relative to surement and control of altitude when wheeled robots. the blimp is <5 m above a surface. The upper part of the figure depicts For either blimp, the video signal two of the blimps, which have lengths of could be utilized in conjunction with 2.3 and 1 m, and are commercially avail- target tracking software running on a able as toys or advertising devices. The computer in a remote control station, smaller blimp has a total mass of 200 g, such that the blimp could automatically 1-Meter and 2.3-Meter Radio-Controlled Blimps maneuvers by use of fan motors, operates approach a target chosen by a remote under radio control, and carries a video operator. Either blimp could easily pass camera and transmitter. It is equipped through an open door, climb an open with a JPL-fabricated biochemical collec- stairwell, or rise to look through a win- tor in the form of a small cylinder filled dow. It could enter an elevator that was with activated carbon and sandwiched by remotely operated or that had been two open-cell filters. As shown in the manually set to open at a floor under lower part of the figure, the biochemical surveillance. It could place small re- collector is mounted behind a fan motor, mote surveillance devices and/or relay so that it automatically becomes filled devices at designated locations, includ- with gas and/or biochemical dust when ing on ceilings. Biochemical Collector Filled by Fan Engine the motor is running. To kick up and col- This work was done by Jack Jones of Cal- lect surface dust, the blimp is made to tech for NASA’s Jet Propulsion Labora- These Miniature Blimps are prototypes of radio- controlled, semiautonomous robots for use in land on its engine cowling and then its tory. Further information is contained in a preventing and detecting attacks on buildings fan motors are turned on. TSP (see page 1) and their occupants. The larger blimp has a total mass of NPO-30443

Hybrid Automotive Engine Using Ethanol-Burning Miller Cycle This engine would operate with high fuel efficiency and generate little pollution. Langley Research Center, Hampton, Virginia

A proposed hybrid (internal-combus- plete combustion. Although the pro- ternal-combustion-engine-driven vehi- tion/electric) automotive engine system posed engine would have a relatively low cles. The disadvantage would be offset by would include as its internal-combustion power-to-weight ratio compared to most the advantages of high fuel efficiency, subsystem, a modified Miller-cycle en- present engines, this would not be the low emission of nitrogen oxides and par- gine with regenerative air preheating problem encountered if this engine were ticulate pollutants, and the fact that and with autoignition like that of a Diesel used in a non-hybrid system since hybrid ethanol is a renewable fuel. engine. The fuel would be ethanol and systems require significantly lower power The original Miller-cycle engine, would be burned lean to ensure com- and thus smaller engines than purely in- named after its inventor, was patented

NASA Tech Briefs, January 2004 21 in the 1940s and is the basis of engines would help to cool the engine, thereby would generate less power per unit vol- used in some modern automobiles, but reducing the remainder of the power ume than does a conventional automo- is not widely known. In somewhat over- needed for cooling and thereby further tive gasoline engine. Consequently, for a simplified terms, the main difference contributing to efficiency. An electrical- given power level, the main body of the between a Miller-cycle engine and a resistance air preheater might be proposed engine would be bulkier. common (Otto-cycle) automobile en- needed to ensure autoignition at However, because little or no exhaust gine is that the Miller-cycle engine has startup and during a short warmup pe- cleanup would be needed, the increase a longer expansion stroke while retain- riod. Because of the autoignition, the in bulk of the engine could be partially ing the shorter compression stroke. engine could operate without either offset by the decrease in bulk of the ex- This is accomplished by leaving the in- spark plugs or glow plugs. haust system. The regenerative preheat- take valve open for part of the com- Ethanol burns relatively cleanly and ing also greatly reduces the external en- pression stroke, whereas in the Otto- has been used as a motor fuel since the gine cooling requirement, and would cycle engine, the intake valve is kept invention of internal-combustion en- translate to reduced engine bulk. It may closed during the entire compression gines. However, the energy content of even be possible to accomplish the re- stroke. This greater expansion ratio ethanol per unit weight of ethanol is maining cooling of the engine by use of makes it possible to extract more en- less than that of Diesel fuel or gaso- air only, eliminating the bulk and power ergy from the combustion process with- line, and ethanol has a higher heat of consumption of a water cooling system. out expending more energy for com- vaporization. Because the Miller cycle The combination of a Miller-cycle en- pression. The net result is greater offers an efficiency close to that of the gine with regenerative air preheating, efficiency. Diesel cycle, burning ethanol in a ethyl alcohol fuel, and hybrid operation In the proposed engine, the regener- Miller-cycle engine gives about as could result in an automotive engine sys- ative preheating would be effected by much usable output energy per unit tem that satisfies the need for a low pol- running the intake air through a heat volume of fuel as does burning gaso- lution, high efficiency, and simple en- exchanger connected to the engine line in a conventional gasoline auto- gine with a totally renewable fuel. block. The regenerative preheating motive engine. This work was done by Leonard Weinstein of would offer two advantages: It would en- Because of the combination of pre- Langley Research Center. Further informa- sure reliable autoignition during opera- heating, running lean, and the use of tion is contained in a TSP (see page 1). tion at low ambient temperature and ethyl alcohol, the proposed engine LAR-16365

22 NASA Tech Briefs, January 2004