An

                                                                                            Alternative

                                                                                                     to

                                                                      “Birdflight as the Basis of Aviation”

AerForce technology uses microfluidic linear spanwise jets to entrain air and cause the air to follow small radius channels for a new world of mass market personal VTOL flight vehicles, drones, delivery vehicles, robots, and more by reducing cost and increasing safety, control, and lift/mass. AerForce technology provides low cost, low noise hovering “vehicles” without rotating blades.

Flight can reduce path length and travel time in addition to reducing the costs associated with road, rail, and waterways. See Appendix 1 “Why Fly”.

Figs. 1&2 below are section views of an AerForce array showing parallel cells composed of polymer film or metal foil forming crescent shaped air supply channels, spanwise linear jets, and parallel propulsion channels. The cellular structure array can contain thousands of cells and multiple arrays can be used to increase power, control, and safety.

                                              Fig.1 AerForce Array Section View

                                                                  Fig.2 AerForce Array Section View Closeup

                                                                                     Fig.3 AerForce Array Front View Schematic

                                                                                                                      Scale

Air following a curve results in a radial outward pressure inversely proportional to the curve radius (1/r). A large number of small lifting elements can have higher lift/mass than a single large lifting element. Legacy aircraft lifting surfaces can have radius in meters, while AerForce lifting surfaces can have radius in millimeters and below.

AerForce technology uses the radial outward force resulting from the linear jets and entrained air being forced to follow curved channels of small radius. As the radius approaches zero, the pressure approaches infinity.

The radial outward force is proportional to the air density times the square of the air velocity divided by the channel radius (ρV²/r). See MIT “Streamline Curvature and Lift Generation” Pg.8 chromeextension://efaidnbmnnnibpcajpcglclefindmkaj/https://web.mit.edu/akiss/Public/streamlinecurvature.pdf

AerForce arrays can provide high lift at zero forward velocity via high internal air velocity and small channel radius, providing hover and high lift capacity at low cost.

A large number of linear microjets increases the area for momentum exchange and mixing between jet air and atmospheric air.

System area can be achieved with vertical arrays, reducing horizontal footprint.

Increasing lift/mass increases propellant capacity, duration, and range. Liquid air as a low cost make anywhere propellant is very attractive for AerForce systems. See Appendix 2 “A liquid Air Economy”.

Scalability. Modularity allows a large range of  system sizes, from microscopic to very large scale.

                                                                                                           Safety

Aircraft can include bilateral groups of arrays above the craft for stability and safety.

Ability to stop in flight.

Simplicity.

Reduced number of moving parts.

High degree of parallelism.

Low mass and low velocity can reduce indoor hazard. A knitted stainless steel mesh grill can further enhance safety.

                                                                                                        Structure

Propellant intake and distribution manifolds can be integrated with array structure. Curved film/foil elements with corrugated meridional passages can be placed between supply channels to consolidate arrays for more robust structure and to allow operation at high pressure. The corrugated interlayers for metal foil arrays can be fine wire cloth to increase heat exchange area, allow perpendicular flow, and provide flame holding and catalyst support. Metal array structures can be rigidized by brazed consolidation somewhat analogous to automotive radiators. Polymer film array structures can be consolidated by solvents and/or adhesives to create more robust structures and allow higher operating pressures. Pressures can be constrained by tensile elements normal to array span. 

The Grill. Stainless steel knitted mesh can be a protective grill and a tensile structure for high pressure operation.

                                                                                                        Craft Forms

Bare array. Legacy wing form cockpit via polycarbonate sheet with AerForce arrays above wing. Box wing with AerForce arrays between upper and lower wing. Inflatable wing. Catamaran. Trimaran. Raft. Torus. Automobile like cabin. Chair with array pair/s. Inflatable forms. Cylindrical and hemicylindrical polycarbonate enclosures with photovoltaic surface. Transparent urethane skin with umbrella structures can act as a lifting body in translation. Cabin floor can be composed of propellant cylinders. Bicycle wheel structure with tire as fluid conduit.

Inflatable elements can be used for lifting surfaces and for crash protection.

                                                                                                             Control

Vectored thrust via varying array altitude, azimuth, and differential flow. Bilateral pairs of arrays can prevent translational motion when desired. Arrays can be paired in square propellant supply structure with arrays rotatable around vertical elements of square supply structure.

                                                                                                    Flow Organization

System flows can be laminar for efficiency. Laminar drag is proportional to velocity whereas turbulent drag is proportional to the square of velocity. Turbulent flow can be used to maximize exchange between jet and atmospheric air.

Flows can be organized to maximize lift or minimize the energy needed for flight. The angular range of the array in Figs 1& 2 is 90 degrees and is biased for hover.

The linear jets use periodic passages which can be created by periodic printing of adhesives. Jet region lower film surfaces can be corrugated and/or otherwise plastically deformed for jet optimization. Intermediate elements can be used to create desired jet form. Jets can be convoluted/corrugated to increase coupling area. Jet exit can have planar vee form to increase coupling area.

Pressure adjusting jets. Flexible exit may induce flutter for pulsating flow.

Supersonic velocity can be achieved with Laval (C-D) nozzle form. Microfluidic 2D (C-D)nozzle arrays can be created by deformations in film/foil near jet exit.

Mach 1 requires less than 1 atmosphere pressure. Shop air can provide 8 atmospheres.

Propulsive channel form and associated supply channel form can vary with application. Intake area can differ from exhaust area. The angular extent of the cells can vary with application i.e., greater for stasis and lesser for translation. The cell form can vary with application.

Deicing can be provided by heating propellants.

AerForce arrays can be used to aid legacy aircraft. AerForce cells can be used as boundary layer accelerators on legacy aircraft. Singe cell AerMovers can be employed at the upper surface trailing edge of airfoils to reduce stall, increases lift and propulsion.

                                                                                                  Propellants/Propulsion

Compressed air, pedal powered centrifugal blower, tethered power, liquid air, hydrogen, hydrocarbons, alcohols, alcohol/water mixtures, photovoltaics, batteries, internal combustion engines, and fuel cells. Black arrays can benefit from solar heating.

Simple high power density internal combustion jet engines with high lift at zero forward speed and positive feedback loop analogous to ramjets. Reactive propellants are gasified in supply channels by heat from propellants reacting in the propulsion channels. Liquid reactants can be supplied at high pressure via pumps. Engines can be constructed from 50um AISI 347 stainless steel foils and consolidated by brazing curved corrugated foils between supply channels.

Supply channels and corrugated spacers can provided high rate heat exchange for liquid/gas phase transition in Power density ∝1/L. Force density is inversely proportional to radius. High force/mass can be achieved with small radius.

AerForce microjet engines. Combustion can be continuous or periodic.

Propellant pumps can act as throttle. Pedal powered pumps are attractive.

Vertical bifacial photovoltaic arrays can be suspended below craft for operating air compressor for propulsive air and for other applications such as sensors.

Photovoltaics can be used to liquify air on the ground for propulsive uses.

Propellant storage can provide crush space.

Elastic pressure vessels can be used to store pressurized propellants, providing more even pressure, and reduced shipping and storage volume.

A high lift/mass allows a large propellant mass to be flown. A low cost propellant with low energy density can be viable. Liquid air is a low cost propellant that can be made anywhere via photovoltaics. Pumps can be used to pressurize liquid air for increased efficiency, provide throttling, and to allow unpressurized liquid air storage. Gasification of liquid air can be via metal foil arrays acting as heat exchangers. Photovoltaics and liquid air offer low cost make anywhere propellant for flight and much more.

                                                                                                       Applications

Mass market VTOL personal aircraft become possible via decrease in cost and increase in safety and power density. 

A human flier can use a single overhead array with the ability to vary flow to the left and right side of array for directional control and vertical control via overall flow. Propulsion can be via backpack supply, the simplest being compressed air.

Eye in the sky. A low cost eye in the sky for communications, police, fire, and traffic management with a real time gods eye view for automated vehicles.

Arrays of low cost AerForce eyes in the sky can be tethered, inflight refueled, periodically replaced, and powered by suspended vertical bifacial photovoltaic arrays.

Long term hover is attractive for many applications. Cameras, communications, radar, advertising, and lighting where and when you want it via control.

Indoor flight. Reduced noise and footprint bring flight indoors for warehousing, patrolling, inspecting, manufacturing, and general travel for people and goods.

Tethered applications include manufacturing robots with a wide range of motion suspended from the ceiling.

Short haul applications are many. Crossing the river, and package delivery via disposable delivery drones via compressed air, especially with parent aircraft to reduce propellant needs.

Low cost drones with low radar and IR signature. 

Sky crane. Construction aid.

Agriculture. Watering, spraying, crop monitoring, planting, harvesting, security, and tree trimming.

Vacuum. The intake face of an AerForce array placed near a flat surface can be attracted to that surface. Rollers can be used to maintain desired distance for inspection, window washing, and painting.

Self-propelled air heater powered by propane or natural gas.

HVAC. AerForce technology will provide quiet, personalized, temperature controlled airflow and the supply of makeup air will be clean with humidity control and personalized scent if desired. Compressed air will become a common household and business utility. HVAC uses include fan, ventilator, heater, cooler, and humidifier. A compressed air supply can provided clean temperature and humidity controlled air to arrays. Expansion cooling can be a significant contributor to air conditioning.

AerForce arrays are attractive for lighting, signage, and display. The arrays can be colored, illuminated, made into displays signage, billboards, and art.

Transparent polymer arrays can transport light via Total Internal Reflection (TIR) within the walls to emission regions.  

Supply channels can be connected behind jet tubes to allow continuous jet tubes.

Wind Energy. Wind accelerated between the tubes reduces pressure in the jet region and causes flow through the system that can be used to drive upstream generators. Parked craft can be recharged by wind energy. AerForce wind energy systems can be sufficiently low in cost to be used as wind walls, on building parapets, ships, ++ and can flex in high wind. Pole mounted units can us the pole for fluid conduit. Billboards and signage can be wind powered. Sailboats can have wind to electric power when travelling or static. Soaring craft can add energy during descent. 

Sailboat with active sails. Vertical AerForce arrays that can power a vessel when wind is not available and derive wind power when wind is available directly and via remotely generated electricity.

AerForce arrays can be easily stored for parking, for other flight modes, and can be flat packed for shipping.                                                                           

                                                                                                              Epilog
 Hovering opportunities are immense.

A great way to enjoy the beauty of our place.

Very light weight arrays can be constructed from polymer film and the array described below can weigh less than 10kgs.

A 1m X 1m effective aperture area with 2mm vertical cell size and 2mm chord length =500 cells and 500 meters of jet length.

The effective horizontal area of the array is equal to the horizontal chord length of the supply channels times the channel span length times the number of channels or 0.002m X 1m X 500=1m²

Units. Mass m in kgs.

            Velocity V in meters per second m/s

            Radius r in meters.

            Density ρ in kgs/m³

            Area A in m²

            Pressure Pa in Pascals

Assume ρ=1.25kgs/m³ , V=10m/s,   r=0.001m.

A pressure gradient proportional to ρV²/r yields 1.25 X 10²/0.001=125,000Pascals or 1,274kgs lift for the 1m² array.

These technologies are Patent Pending and the property of johnmpopovich@gmail.com

                                                                                                  Appendix 1

                                                                                                   Why Fly

Flight is “innately” cheaper, safer, faster, and more enjoyable than surface travel.

                                                                                                             Flight is cheaper 

Birds travel an order of magnitude faster than their earthbound brethren with equal mass and metabolic rate and therefore use 1/10 the energy to transport a given mass a given distance (“A sparrow, which is identical in mass and metabolic rate to a mouse, flies an order of magnitude faster than a mouse runs, and so has a minimum cost of transport an order of magnitude lower than that of a mouse” Proceedings of the National Academy of Sciences USA, Volume 95, pages 5448-5455, May 1998 Engineering). And sparrows are on the low efficiency end for birds, with the soarers like albatross at the top.

Birds are also able to travel more directly between two points and to exploit favorable air motions. There are many instances where surface vehicles have to travel great distances to access a nearby region because of water or mountains. The San Francisco Bay Area is a typical example where hours can be spent in traffic to access a region a few miles distant. Surface travel in these circumstances can be hundreds of times costlier and more time consuming than flight.

Maintaining a flight infrastructure is much less costly and disruptive than maintaining a system of roads, rails, and streams. Flight transport can reduce road traffic and has no road, rail, or stream width limitations. Surface (2D) transportation requires an enormous amount of time and resources for construction and operation.

Everyone on Earth is connected by air, flight joins people separated by mountains, oceans, and hostile intermediaries. Flight can greatly reduce the resources needed for transportation.

Why should aircraft cost more than cars? Flight vehicles can have more even structural loading. Automobiles have four small contact patches and must be strong enough to suffer indignities like hitting a pothole while braking. Roadable aircraft have been poor cars. Aircraft can be lighter than cars per person or per unit payload, Consider the vehicle mass per person in planes, cars, trains, and ships.

                                                                                                                             Flight is Safer

Flight allows for greater distance from surface obstacles and between vehicles. Roads represent a small portion (~1%) of the Earth’s surface and are restricted to the surface. Flight vehicles can cover 100% of the Earth’s surface and access a large number of flight levels via 3D rather than 2D travel. The distance between vehicles can be much greater via increased surface coverage, additional flight levels, straighter paths, and shorter trips. Flight vehicles can travel at steady and predictable speeds and air transport is more automatable. Reduced blocking from surface obstructions aids cameras, RADAR, LIDAR, SONAR, vehicle to vehicle, vehicle to ground, and vehicle to satellite communication. We also have much more experience with automated flight.

The safety of legacy flight vehicles is compromised by the need to take off and land at high speed, the proximity of other vehicles at the takeoff and landing sites, the need to maintain a certain speed to be airborne, and the lack of passive safety features.  

Flight vehicles with thrust greater than mass can provide increased utility, including the ability to stop in midair, change direction rapidly to prevent collisions, easily refuel inflight, and takeoff and land in dense urban environments.

Flight vehicles also can be designed to have stable high drag descent and controlled structural deformability, making collisions and forced landings less dangerous. Ballistic parachutes can provide additional safety.

Multiple technological advancements have increased our ability to develop low cost, robust, integrated control, communication, and navigation systems that can provide greatly increased travel safety and convenience while reducing resource expenditure.

                                                                                                                   Flight is Faster    

Flight paths are more direct and do not suffer the speed limitations associated with surface obstructions encountered by road, rail, and water vehicles.

Flight offers time saving for people and critical cargoes and capital cost can be reduced by more frequent flights.

                                                                                                            Flight is More Enjoyable

Earth from above is more beautiful, our view of it is much greater and it yields a better understanding of our environment. Flight is typically smoother as it does not require the stopping and starting associated with surface travel and it allows much greater freedom of movement via the third dimension.

                                                                                                                          Epilog

This is the time in our history for the transition to flight. We need to reduce the cost and planform area for personal vehicles capable of vertical takeoff and landing (VTOL).

Mass market personal air travel requires reductions in cost and increases in safety and power density. Entry level 2 place helicopters (Robinson R22) cost ~$400,000.00, 10X the cost of a car and require large rotor swept areas (46m² ). Power per unit plan area needs to be increased ~10X for compact VTOL vehicles. Helicopters also require skilled operators.

Progress in computers, artificial intelligence, radio communication, GPS, cameras, LIDAR, RADAR, SONAR, and inertial sensors, have the potential to greatly increase safety and efficiency, while reducing necessary operator skills.

Much of the area of a city is taken away by roads and parking regions. Personal aerial vehicles do not require roads and can park from above, thereby reducing parking space access roadways. They can park on roofs to greatly reduce the need for a retailer/homeowner/+, to have a parking region. They also increase security and allow our cities to be walkable, bikeable, and livable. All of a sudden, a lot more room is available in cities. Apartments, cafes, markets, parks, amphitheaters, + seem a better choice than parking lots. Upward mobility is the future.

Ford felt the automobile could free people from the vagaries of the mass transit system. We now need to be freed from the vagaries of the automobile. The wheeled cart has been very useful but it’s time to rise above it. 

                                                                                                        Appendix 2

                                                                                              A Liquid Air Economy

                                                                                                  Why Liquid Air?

A liquid air economy has many benefits. Liquid air can be made anywhere, no need to mine it, no need to refine it, it is non-polluting, relatively safe, and it can be made at low cost with SuperHero Claude cycle liquefiers.

Fig. 1 SuperHero Claude Cycle Compressor and Liquefier Schematic

The motor driven SuperHero turbomachine in the upper spherical container in Fig.1 uses recirculating water as a periodic liquid piston to provide near isothermal air compression.

The compressed air from the upper spherical container can be expanded in the lower spherical container by a SuperHero expander turbine to liquify the air in a Claude cycle.

Liquid air can provide short-term and long-term storage for intermittent sources including photovoltaics and wind. Liquid air storage does not require pressurization.

Liquid air is attractive as a “utility.” It is cheaper to distribute liquid air in a district or a building for air-conditioning, air make up, compressed air, refrigeration, electricity production, electronics cooling, and electronics powering, than to provide these services individually. Liquid air can be supplied via a recirculating loop manifold. Personalized cool, clean fresh air can be provided at low cost and with low noise. Heat can be added via electricity from SuperHero liquid air turbogenerators.

Compressed air is an attractive utility and would enjoy greater use with greater access. Superhero turbomachines can provide quiet compressed air at low cost. Compressed air can be provided by SuperHero liquid piston recirculating water air compressors, by liquid air ported to a storage vessel, closed off from the liquid air supply vessel and heated by the local atmosphere to evaporate and thereby pressurize the air in a compressed air storage vessel, by a pump made from a pair of check balls with a heat exchanger between, and by liquid air pumps with downstream heat exchangers.

Liquid air can be transported by pipelines, trucks, trains, planes, and ships. Storage can be refilled as needed.  

Liquid air allows existing fuel stations to become liquid air stations. Existing tanks can be internally insulated for liquid air storage. Liquid air is storable without pressurization. Oil and gasoline storage tanks can be converted to liquid air storage tanks. Liquid air can be stored in underground cavities,

Liquid air offers fast fill vs. the long waits associated with battery systems.

Liquid air controls require less cost, mass, and volume than electrical controls, including those required for automotive battery systems.

Liquid air storage vessels can be used as structural elements for mobile and stationary systems. Car, truck, train, plane, and ship structures can be made of tubes that can be used for liquid air storage. Truck and train chassis are very attractive candidates for tubular structures. Building structures can be formed from tubes used for cryogenic liquid storage.

Energy efficient buildings often suffer poor air quality as a consequence of reduced communication with the local atmosphere and liquid air can provide clean air in these applications. Clean makeup air can be especially valuable in hospitals. Operating rooms lamps can be designed to emit clean air to displace room air and operating team emissions in addition to liquid airs ability to provide cooling for the light sources and associated electronics.

Energy is proportional to pressure and liquid air at high pressure can have energy densities ~200Whr/kg, less than Li-Ion, but greater than Lithium Iron Phosphate, which Tesla and other EV mfrs. are transitioning to due to the reduced cost and increased safety. Electric vehicle batteries require costly heating, cooling, and control systems that further reduce their useful energy density. Liquid air powered vehicles have reduced mass with travel, especially important with aircraft.

Liquid air SuperHero atmospheric source heat engines can provide power densities 10-100 times as great as electric motors and without the concern of overheating. 

In server farms Superhero liquid air turbogenerators can both power and cool the electronics. Electronics can operate at much higher power densities and with better efficiency, reliability, and durability via lower operating temperatures and modularity. Cryogenic cooling allows the use of lower bandgap semiconductors such as Germanium.

A liquid air economy will use liquid nitrogen and liquid oxygen. Liquid oxygens reactive potential makes it much more valuable than liquid nitrogen. Liquid oxygen can be used for combustion to greatly improve power density and to prevent oxides of nitrogen, it can be used for breathing, it can be used for high altitude operation, including rockets for point to point and space travel, and it is useful in many chemical processes. Liquid oxygen can be used for a  SuperHero combustion engine topping cycle and liquid nitrogen can be used for a SuperHero cryogenic engine bottoming cycle.

                                                                                                      SuperHero Atmospheric Source Heat Engines

SuperHero Atmospheric Source Heat Engines can have high thermodynamic efficiency with cryogenic fluids.  Additional benefits include safety, no need for ignition, no reaction time limits, no combustion space needed, drag heating utility, and boundary layer viscosity reduction via reduced temperature. See neweconomytechnology.com

Atmospheric source heat engines are limited by atmospheric air mass flow rate and this can be increased by increasing travel speed, a positive feedback loop.                                           

                                                                                                                        Bottom up Thermodynamics

Thermodynamic efficiency is limited by the absolute temperature ratio. Sadi Carnot gives us the thermal equivalent of height. If the temperature ratio is half, half of the thermal energy can be converted to work.

 Maximum thermodynamic efficiency=1-T_low/T_high.  For liquid air T_low @78⁰K and ambient temperature T_high @273⁰K (1-78/273=0.71), or 71% maximum thermodynamic efficiency.

To achieve a similar thermodynamic efficiency with ambient temperature being T_low, T_high must be ~900⁰K (1-273/900=0.7). The higher operating temperature requires costlier materials and implies heat loss to the environment rather than heat gain from the environment as is the case with liquid air.

SuperHero turbomachines with cryogenic propellants can convert sensible heat from atmospheric air and latent heat from atmospheric water vapor to rotational motion which can be used for electricity generation, shaft work, or thrust.

Atmospheric energy conversion. Air specific heat @300K=1kJ/kg.K. A liquid air powered vehicle travelling at 120k/h (33m/s) provides ~40kg/s of atmospheric air to a 1m² aperture. 40kg/s X 100⁰K ∆T X1kJ/kg.K =4MJ/s or 4Mw_t. A portion of the thermal energy can be converted to rotational energy by SuperHero turbomachines and used to generate electricity, mechanical drive, or thrust. 

Atmospheric energy conversion. Latent heat. Water liquid/gas latent heat of phase change energy =2.3kJ/gm. A vehicle travelling at 120k/h (33m/s) provides 33m³/s of air to a 1m² aperture. Air at STP and 50% humidity contains 33m³/s X 11.5 gms H₂O/m³ X 2.3kJ/gm=873kJ/sec or 0.87Mw_t. 100% humidity doubles this figure. Cryogenic SuperHero turbo machines can provide freshwater from the atmosphere via condensation.

SuperHero cryogenic turbomachines are attractive for working in hot areas, foundries, metalworking, ceramics, and glass industries. SuperHero cryogenic liquid nitrogen turbomachines are attractive for working in flammable and explosive environments.                               

                                                                                                                   Cryogenic CO₂ Capture

SuperHero cryogenic turbomachines can benefit from the exhaust temperature from carbon containing fuel combustion and change the phase of CO₂ in the exhaust from a gas to a solid while delivering useful power. The CO₂ can be inertially separated at the source vs. trying to separate CO₂ from the atmosphere @400 parts per million.  

LNG regasification facilities can be used to produce liquid air.

A thermos of liquid air and a small cryoturbine fan can provide a portable air conditioner without electricity.

 Liquid air SuperHero turbomachines can power refrigerated delivery vans. Large numbers of refrigerated trucks spend their day in traffic with engine idling and with the refrigeration system operating to keep the food cold and with an air conditioner to cool the operator.

 Liquid air can be used for projectile propulsion.

 SuperHero cryogenic turbomachines can use heat from solar radiation, engine exhaust, industrial processes, and other sources to increase efficiency and power density.

                                                                                                                               Epilog

 Liquid Air Vehicles (LAVs) will displace EVs due to lower overall cost, including lower overall environmental cost. We will look back and say, “You know there were people who thought that batteries would be cheaper than air.” Despite efficient manufacturing and direct selling, Tesla vehicles are expensive, and very heavy.

You cannot create batteries with photovoltaics, but you can create liquid air. PV can be used to create liquid air directly vs. batteries.

Batteries can’t be made from photovoltaic electricity, in fact Tesla does not even have his factory roofs covered with PV. The mining, refining, and manufacturing are costly.

The future is cool.  

                                            SuperHero Microturbines

                                                                                                                       Why microturbines?

Power density is inversely proportional to length (1/L). Small turbines have the potential to reduce the cost, mass, and volume per unit power output and they are more amenable to mass production. 

SuperHero technology encompasses a family of microturbines that include relatives of Hero’s Aeolipile.

SuperHero technology allows high power/cost, high power/mass, and high power/volume microturbines. The family includes atmospheric source heat engines, internal and external combustion heat engines, topping and bottoming cycle heat engines, boiler feed pumps, immersive self-propelled, self-cooled, liquid rocket turbopumps, thrusters, fans, condensers, expanders, liquefiers, mixed flow compressors, motors, generators, power convertors. centrifugal blowers, open and closed cycle air conditioners, dehumidifiers, and reactors.

Superhero microturbines can provide power on a scale appropriate for homes, vehicles, and persons.

SuperHero microturbines can provide power as needed, when needed, where needed, and with the voltage/current ratio needed via modularity and without the long construction times associated with legacy power plants.

Superhero microturbines can provide reliability, maintainability, and throttleability by modularity.      

Superhero microturbines can provide combined heat and power (CHP). ~60 million U.S. homes have natural gas supply. A SuperHero microturbogenerator with exhaust heat used for space heating and water heating can have >90% overall efficiency, provide reliable low-cost electricity and reduce grid dependence. Natural gas is less costly than electricity and less subject to outage.

SuperHero microturbogenerators are attractive for uninterruptible power supplies and emergency power production.

SuperHero backpack microturbogenerators can provide electricity and compressed air for construction and landscaping tools. SuperHero microturbine driven machine tools can provide high power density and cooling.

Why haven’t microturbines been more successful, despite the potential benefits?

Large turbomachines dominate in commercial air transport and electricity generation, but when the size of legacy turbomachines is reduced, some of the beneficial characteristics are reduced, often to a degree that render them unable to compete with other means.

Cost: the cost of legacy turbomachines is due in large part to the manufacturing processes associated with complex blading and the cost of materials able to operate with high thermal and mechanical loads. SuperHero microturbines incorporate manufacturing simplicity and commodity materials.

Efficiency: efficiency is proportional to L^2/3 (square/cube law), but the loss mechanisms associated with scale reduction in turbomachines are mitigated in SuperHero microturbines by using enclosed passages to avoid rotor to stator leakage, by the use of liquid working fluids, and by advantageous heat exchange with the environment associated with increased surface/volume, especially with cryogenic fluids.

SuperHero microturbines use rotating tube arrays as compressors or blowers and the rotor drag can also be useful thermodynamically, especially in the case of cryogenic liquid propellants.

Shear force: the reduction in passage size associated with scale reduction in microturbines implies increased shear force per unit fluid flow (<Re) and this increase in the ratio of shear to inertial force is associated with increased drag. The relative shear force increase may be inevitable, but not inevitably bad. Small passages allow increased heat transport rates and SuperHero microturbines can be designed to operate with laminar flow where drag is proportional to velocity rather than the square of velocity associated with turbulent flow. Laminar flows also produce less noise.

A classic argument against tip jets is that efficient operation requires unrealistic tip speeds.

SuperHero microturbines combine modern materials and proprietary design to allow much higher tip speeds than legacy reaction turbines and the technology provides several means to use the energy downstream of the jets, including rockets, concentric contrarotating radial outflow impulse turbines, contrarotating tipjet rotors, entrainment, volutes, blown wings, and deswirl vane arrays.

                                       Fig.1 SuperHero Tipjet Reaction Microturbine

The radial tubes in the arrays of Fig.1 are composed of 1.5mm OD X 0.1mm wall thickness (17Ga) 304 stainless steel hypodermic tubing. Superhero microturbines can generate higher pressures in a single stage than multistage legacy microturbines by using liquid propellants.

The rotating tube arrays in SuperHero microturbines cause fluids introduced through a central hollow axle to be accelerated in the tubes and ejected tangentially at the tube ends or returned to the hollow axle via “U” tubes.

The tube arrays can be configured as centrifugal, axial, or mixed flow compressors and blowers.

SuperHero microturbines are rotating high power density heat exchangers capable of extremely high pressures i.e., thousands of atmospheres. The extreme pressures are confined to small regions which also serve as high-rate heat exchangers. Torque can be additive and/or subtractive.

A large population of small jets allows increased coupling with the neighboring airstream for mass, momentum, and heat transfer. Jet expansion causes a reduction in temperature that can be mitigated by close association with the neighboring airstream. The neighboring airstream may be at atmospheric temperature or preheated.

SuperHero microturbines can have many rotating tube arrays and bilateral entry.

Fig. 2 SuperHero Tipjet Reaction Turbine with Backswept Passages

Fig. 2 is a SuperHero centrifugal microturbine rotor comprising a backswept stainless steel hypodermic tube array with C-D nozzles via plastic deformation and with brazed 4GPa tire cord wire supporting rings. Backswept tubes reduce drag and increase fill factor                                         

                                            Fig.3 Contrarotating Parabolic Tube Array Schematic

Fig.3 is a pair of contrarotating radial reaction turbine arrays that can provide intense mixing and add torque to opposing turbine array. The jets from one rotor encounter opposing high velocity flows from neighboring rotors. The contrarotation can provide intense mixing, reacting, and combustion.

Fig. 4 SuperHero Tipjet Reaction Turbine with External Impulse Contrarotor

In Fig. 4 the SuperHero inner reaction turbine output drives a concentric contrarotating impulse turbine and the large number of nozzles provides high power density. One or more concentric contrarotating impulse turbine stages can be used in radially outflowing SuperHero microturbine systems to provide output power with increased efficiency, lower output rotational rate for connection to drives, reduced exhaust temperature, and reduced exhaust velocity.

Contrarotor spokes can be increased in number and used to induce air.

SuperHero microturbines can provide net positive suction head for pumping unpressurized propellants.

The incoming fluid passage between static axle and rotor can provide a hydrostatic journal bearing.

A rotor with 0.1m radial length liquid phase rotating at 45krpm will develop a centrifugal pressure equal to (1/2ρr²ω²). A liquid air density ρ=870kg/m³ X 0.5 X 0.1m² X ω4,710²=9.65 X10⁷N/m² or 965atm with an angular velocity of 471m/s.

17 Gauge thinwall 304 SS hypodermic tubing has an OD of 1.5mm, a wall thickness of 0.1mm, and a tensile yield strength of 944MPa. The hoop stress at 1,000 atmospheres (s=pr/t) is 650MPa, which yields a safety factor of ~1.5 at 1,000atm, and the high pressure is confined to a small region, allowing low wall mass and cost. 2GPa 301 stainless steel allows 2X pressure increase and 4GPa wire braided sleeve and helical bottlebrush inserts allows much greater pressure increase.

Low temperature and cryogenic SuperHero microturbines benefit from increased material strength at low temperature and the ability to use advanced nonmetallics such as carbon fiber and graphene.

A helical “Bottlebrush” internal structure can be used to provide an array of ties normal to the tube axis to resist outward pressure forces and provide extended surface area for heat exchange. The bottlebrush can use 4GPa wires and attach to the tube ID by brazing. Adding a helical moment counters the Coriolis force causing flow to follow the trailing edge of the tube wall and prevents Dean vortices due to tube curvature. 4GPa central twisted wire can provide increased axial  tensile strength. The bottlebrush can be catalyzed to react with fluids in passage for combustion or operation as a chemical process reactor.

The thinwall tubes and high rotation rates in SuperHero microturbines provide high heat transfer rates, but extended surfaces can be used to greatly increase heat transfer rates. Commercially available 635 mesh (635 wires/inch in each of 2 axes)=(250 wires/cm in each of 2 axes) stainless steel twill weave wire cloth with 18um wire can be used to create a very high heat transfer rate rotating heat exchanger/engine.

The wire cloth elements can be bias cut at 45⁰ to equalize heat transfer for wires in both axes and to reduce edge affects. The wire cloth elements can be anchored at the hub and brazed to the tube arrays.

Custom wire arrays can use high strength steel wires with copper cladding for increased heat transfer and brazing. The wire arrays can be brazed to the trailing edge of the tubes, making the tube arrays part of a hierarchal flow organization.

The rotating wire cloth arrays are somewhat analogous to crossflow filtration schemes. The high surface velocity parallel to the wire cloth arrays and the pressure difference across the wire cloth arrays provide very high heat transfer rates. The system can be designed for air to make a single pass through the capillary mesh.

SuperHero hierarchal microscale heat exchanger power density is due to the high surface/volume ratio associated with the fine wire mesh, the related thin boundary layers, massive end stage parallelism, and laminar flow.

Ref.1 details free convection heat transfer from small features. Pulavarthy Thesis “CHARACTERIZATION OF HEAT TRANSFER COEFFICIENT AT MICRO/NANO SCALE AND THE EFFECT OF HEATED ZONE SIZE.”

“The measured heat transfer coefficient varied from 4650 W/m²K in a 10 μm X 20 μm freestanding specimen to 16,300 W/m²K for the same specimen 2 μm away from a neighboring solid surface”. “It is to be noted that the results discussed in this section are for the experiment carried out at atmospheric pressure.”