Low Cost Stealth UAV

During disputes countries try to ramp up their military manufacturing capabilities with limited resources. I thought of a stealth UAV design that requires minimum export including the fuel. A liquid air powered plastic plane.

Liquid air when warmed to the ambient temperature expends 700 times from its liquid volume. This produces a rocket like thrust. Low temperature operation allows the fuselage and the wings of the plane to be made of clear HDPE plastic. Clear plastic filled with liquid air would be hard to identify from a distance. Combustion and propeller free propulsion allows silent operation. No heat signature on the exhaust and no radar reflection due to use of plastic. Liquid air cannot produce thrust for long time. The design of the plane would determine the range and speed of the plane. I propose eight flat wings to generate lift for the plane. The angle of attack would generate lift on the thin flat wings. The plane would be controlled by two ailerons placed on its back. The clear plastic fuselage and the fuel allow internal camera, RF and GPS antennas. Simple unibody design of the plane allows mass manufacturing using molds. HDPE becomes brittle at cryogenic temperatures. Therefore, the plane would need to be recycled and remolded again after several use. Liquid air leaves no residue hence the recycling wouldn’t require any chemicals.

The plane would take off by a small explosion inside the plane which would generate enough heat to expand enough liquid air to generate takeoff thrust. A tiny Li battery can be shorted for this purpose or a small charge can be fired.

Kamikaze version of the plane would be fueled by liquid air with higher oxygen concentration. Nitrogen would be still needed for stabilization. Once the plane reaches the target, a Li battery can be shorted to put the plane on fire or a small charge can be fired. Fuselage made of HDPE and liquid air would leave no contamination on the target zone after the fire.

Mineral Exploration Using Rovers

Mars Rovers over the decades have explored the surface of the red planet and supplied valuable information to earth. These robots are a kind of moving lab. They are light weight, reliable and operate with renewable energy supplies. An ideal autonomous mine explorer in the wild.

Mars Rovers, because of their use cases have demanding requirements which make them very expensive. However, a mineral explorer on earth wouldn’t have most of these requirements and therefore can be made much cheaper. More importantly mineral explorers would be mass produced unlike Mars explorers.

The light weight and sturdy design of the rovers allow them to be deployed by drones to remote locations. Unlike space rovers, the ones operating on earth can be supported by mobile telecom relays for high-speed communication. Allowing them to explore caves as well. Additionally, mobile renewable energy generators can be installed in the exploration zone to enable operation even in winter or at night.

Mineral exploration would increase the usage of the rovers and create a market for them. Which would attract high-tech companies to develop technologies for them. These technologies would then be transferred to space exploration.

The objective is to establish a two way now how transfer between deep space exploration and mineral exploration.

Construction on Mercury

When I saw the high Magnesium region on Mercury, the idea appeared on my mind. Using Magnesium and Silicon to construct on Mercury. The high Magnesium region has high magnesium and silicon concentration.

The melting point of Magnesium is 650 °C and the boiling point is 1091 °C.

The melting point of Silicon is 1,414 °C and the boiling point is 3265 °C.

The maximum temperature measured on the surface of Mercury is 430 °C.

These values indicate a straightforward approach to separate Magnesium from the ground and process it. The construction robot send to Mercury would be made of highly reflective material to stay cool from the heat of the sun. Due to lack of atmosphere, the places in shadow would stay cool. The construction robot would first find magnesium deposits with minimal impurities. Then using a special hot wire cutter, the robot would cut away a chunk of Magnesium. This process would be conducted when the sun is shining strong. The heat would already soften the low melting Magnesium. The wire cutter does not need to reach very high temperatures to cut away a Magnesium chunk.

The cut away chunk would then be shaped using the concentrated solar rays. Much stronger solar rays on Mercury compared to Earth would do the job quickly. The shaped parts would then be melted on the edges and merged.

Magnesium is a light weight and strong material. Very low concentrations of humidity and oxygen on Mercury would keep the material strong for a long duration.

The silicon deposits on the surface would also be processed like that to create glasses and insulators.

Non mechanical cut away and shaping process would allow a light weight and long-lasting construction compared to using drill bits and cutting wheels that would wear out quickly on other planets and moons.

By delegating the high energy part of a construction to the sun, a much simpler and low powered robot can be utilized for the construction. Which would mean low weight payload for the mission that would increase the feasibility of the idea.

Altitude Compensated Nozzle

The function of a rocket engine nozzle is to expand the hot engine exhaust gases down to ambient pressure, transforming thermal energy to directed kinetic energy in order to produce thrust. As the rocket ascents to the space the air pressure decreases. As a result, the exhaust gasses overexpand, reducing the effective thrust of the rocket. In order to compensate for the changing ambient pressure, the nozzle need to increase its expansion area.

I thought of a solution which may not work but comparably easy to implement. For the solid booster rocket I proposed earlier, the nozzle does not need to have propellent heat exchangers attached on it. This simplifies the design. A nozzle made of high temperature resistant tungsten alloy would be enough. I propose the nozzle to have multiple sections stacked on top of each other. These stacks will hold in place with a low melting metal such as aluminum alloy. Tungsten is not a good conductor of heat compared to aluminum. As the nozzle heats up, each low melting section will melt away and drop the next nozzle section into place. The thickness of the nozzle section holders would be altered to achieve the adequate delay between each nozzle section drop.

This would be a light weight and zero mechanics solution to altitude compensated nozzle design for solid boosters.

Solid Booster Revisited

I had previously proposed a deep space propulsion system. I improved the design so that it can be used both on the first and the second stages of a rocket as well.

The solid booster would be composed of three sections.

The booster section where the solid propellent is burned and the thrust is generated. This section needs to withstand high temperature and pressure.

The transfer section where the stacked solid propellant is transferred to the booster section. This section should have enough opening to allow the booster section doors to open. This section needs to withstand moderately high temperatures and pressures because the new propellant block needs to be transferred to the booster section while it is still hot and has some pressure.

The storage section where the stacked propellant is stored. This section has no particular temperature and pressure requirement.

The solid booster will fire when the storage section is full and the booster section is loaded with a propellant block. Once the solid propellant inside the booster section is consumed, the booster section doors will open. Then the release latch will be opened to release a propellant block into the booster section. After that the booster section doors will close and the rocket will be fired once more. Finally, the release latch will be closed and the holder latch will be opened to allow the remaining blocks to slide down.

The solid propellant blocks will be molded inside a plastic shell like HDPE. This will allow them to slide down more easily and prevent cracks to the solid blocks. HDPE burns out completely into carbon dioxide and water vapor which would contribute to thrust as well. The solid blocks will have different grain geometries and height to suit to the thrust need. The initially fired block will be optimized for high peak thrust and short burn time to allow takeoff. As the rocket gets lighter, the grain geometry will allow more burn time and lower peak thrust.

The solid boosters require strong shells that are heavy. By shrinking the booster section, the weight saving would be high. Additionally, as the propellent is consumed inside the booster, the thrust goes down due to increased combustion volume due to the void of the consumed fuel. Burning propellant in sections and keeping the combustion volume small increases the efficiency of the rocket.