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The world’s airspace is the greatest under-utilized natural resource at our disposal to address transportation needs. Airways can be the highways of the future if we have viable air vehicles and a means to accurately integrate these vehicles into a controlled airspace.

The technology exists to generate a fully controlled airspace infrastructure using global positioning system satellites (Navstar) (GPS) as the cornerstone of a fully integrated and automated airway system. In the future a family of practical aircraft that would utilize such a system might include:

Only the volantor type of aircraft can address the continuing need for personalized transportation that can go where you want when you want. Today this role is filled by the automobile, but average speeds on many highways are falling dramatically, particularly near urban centers.

Figure 1 suggests that the problem could get much worse if growth trends continue as they have over the last 25 years.

Figure 1. U.S. Automotive Transportation Data

This figure documents that while the U.S. population grew 29% between 1970 and 1995, the number of passenger miles traveled grew over 3 times faster⁽¹⁾ Since the early 1960’s, federal spending in the U.S. on transportation infrastructure declined from 6% of the total non-military budget to 1.2% by 1990⁽²⁾. These limited funds are being used primarily in a losing battle to patch up the present highway system.

The U.S. Transportation Department estimates that by the year 2005 motorists will waste 12 billion working hours caught in traffic. Efforts to use automobiles more effectively have not worked; for example, the Seattle Regional Transit Agency dropped a program, which offered financial incentives of up to $700 to people who participated in vanpools. The goal was to have 270 vanpools in operation after three years. Only 10 resulted. Perhaps even more discouraging is the fact that the average passenger load decreased on every type of transit service between 1985 and 1995 including light rail, heavy rail and buses⁽³⁾. People are remarkably resilient in their unwillingness to give up their personal automobile even when speeds average 3 MPH, as in parts of New York.

Figure 2. U.S. Commercial Airplane Transportation Data

Figure 2 shows that 80% of all commercial flights are less than 900 miles. With airports becoming a nightmare experience, the volantor’s potential to off-load most of this traffic is promising.

 Figure 3. Cumulative Growth of U.S. Transportation Infrastructures

Figure 3 provides a graphic chronology of the fundamental infrastructure changes that have occurred in the U.S. over the last 200 years. This figure shows the pattern of U.S. airway infrastructure growth if it parallels the previous three systems. It projects the airway growth rate only, not the ultimate airway size, which is of course unknown. However, in all previous cases, availability of a viable new system quickly dominated the older one in terms of utilization with each system becoming progressively larger.

What will it take to make the airways the highways of the future for that large segment of the U.S. and world population where personal transportation will remain or will become important? The volantor together with an airway infrastructure could make this possible if the combination is:

The volantor is classified by the FAA as a "powered lift" aircraft. The FAA is also generating a "powered lift" pilot’s license that will be necessary to fly the volantor for at least the next several years.

Moller International has expended approximately 700,000 man-hours over a period of 30 years, designing, constructing, testing and re-working a number of different volantor design concepts and configurations. A large portion of this effort has been devoted to the development and production of the required powerplant. The objective was to progressively evolve towards the ideal form for a volantor. Much of the technology to achieve this ideal was not available 30 years ago including:

Only the Wankel type rotary engine, invented in the late 1950 ’s, has the potential to meet the above powerplant requirements. In fact, over $2 billion has been spent in research and development of Wankel type rotary engines. This is very fortunate, because the unique nature of this powerplant is essential for volantor type aircraft.

The following list reflects the essential elements that were incorporated in the first few aircraft that were developed and test flown as volantor candidates:

Three generically different VTOL aircraft were built in which the above criteria applied:

XM-2 flown in ground effect in 1965

The XM-2 was designed to carry a large payload in ground-effect and then to be ferried out of ground-effect. Ferrying was never attempted since such a flight would have required artificial stabilization that was undeveloped at that time.

XM-3 flown in ground effect in 1969

The XM-3 used a number of distributed engines driving a hub-less ring fan. The fan provided inherent gyro-stabilization but engine power was inadequate to operate out of ground effect.

During the period between 1969 and 1989 many different variations of these aircraft types were tested but were always limited by the engine power available. The Fichtel-Sachs rotary engines used during much of this period in the XM-4 were replaced with modified OMC rotary engines producing significantly higher power. The XM-4 then became the M200X.

The M200X used distributed engines driving individual fans. Control was provided through electronic stabilization and fly-by-wire. This model made over 175 manned flights in addition to many unmanned flights.

XM-4 flown in ground effect in 1975

M200X flown in 1989

In 1990, following the successful flight tests of the M200X in and near hover, development began on a volantor that could cruise efficiently at high speed and carry a useful payload during hover.

Following extensive wind-tunnel model testing and full size propulsion system tests, a volantor configuration was generated that satisfied these additional criteria. This particular volantor, which the press named Skycar, received the first U.S. patent ever issued on what would be termed by the FAA as a normal category "powered lift" aircraft. It has since been patented worldwide. The four passenger M400 Skycar volantor is presently being prepared for its first lift-off.

Passengers ………………….4

Cruise Speed (25,000 ft) …. 325 mph

Maximum Rate of Climb …. 6400 fpm

Maximum Range ……………900 miles

Gross Weight ……………… 2400 lbs.

Fuel Capacity ……………… 40 gal

Operating Ceiling …………. 30,000 ft

Hover Power Required……. 680 hp

The Skycar has addressed reliability, affordability, environment related issues, and support infrastructure as follows:

Historically aircraft and automobiles have cost approximately five times the cost of the power plant, as shown in Figure 4. If this relationship continues to apply then the engines used in the volantor must achieve a particularly low cost per horsepower in order for the Skycar to be generally affordable. Two-stroke engines are achieving user costs as low as $20 per horsepower in volume production of approximately 50,000 units/year⁽⁵⁾. However, the two-stroke engine cannot meet existing emission standards. Lower-emission versions using improved technologies including fuel injection become considerably more expensive. Moller International purchased the original Outboard Marine Corporation rotary engine technology as a basis for its own engine development. This particular rotary engine was shown by OMC to be cost competitive with the volume production costs of their two-stroke engines⁽⁶⁾. However, because the rotary engine operates on the four-stroke principle it can meet expected emission standards.

Figure 4. Relative cost of vehicle powerplants

The Skycar must reach production levels above those for a single successful automotive model (>300,000/year) to significantly impact personalized transportation in any meaningful way. This level of volume production should lead to further reduction in cost per horsepower for the rotapower® engine to $16 per horsepower. The M400 Skycar volantor requires 680 horsepower to hover at sea level. This suggests an M400 Skycar selling price of approximately $55,000.

The Bureau of Labor Statistics states that consumer spending on transportation amounts to 24% of the average American’s personal expenses. It commands more of the average American’s pocket book than even housing or food. If one considers the wasted time actually driving or being stopped in traffic, the average American driver spends about 300 hours per year on the highway. In lost wages this more than doubles the effective cost.

The Skycar has the capability of averaging over 300 MPH from take-off to landing, which could reduce travel time to 40 hours per year for the average user. Historically aircraft depreciation has averaged about 2% per year versus 10% per year for automobiles. If this can be maintained for the Skycar, the actual cost of ownership will be modest while the effective cost, particularity as automotive traffic deteriorates further, will be much less than the cost to the average American who travels 12,000 miles per year.

Figure 5 offers a comparison between the acquisition cost of the M400 Skycar and the 30 passenger VTOL capable V22 Osprey based on cost per passenger seat. The V22 Osprey is far more expensive per passenger seat initially and this differential will substantially increase as production volume increases. The V22 or the BA609 (6-9 passenger version) will not achieve the manufacturing benefits of mass-production that would result if the Skycar replaced automobiles for longer trips and commercial flights for shorter trips.

Figure 5. Acquisition Cost Per Passenger Seat

In a study undertaken by the Boeing Aircraft Company, the Skycar achieved better passenger miles per gallon of fuel burned than their B737. The Skycar’s projected fuel consumption per passenger mile was shown to be 25% of that for the V22, BA609 or helicopters.

The number of Skycar take-off and landing sites called vertiports allowed will be inversely related to the noise it generates. Vertiports located within commercial or downtown areas are likely to tolerate noise levels slightly above those of the traffic background noise (75dba at 50 feet). Residential areas can legally restrict the Skycar if it generates a noise level exceeding 65 to 70dba.

It will be difficult to bring the Skycar noise level below 70dba. However, a number of passive and active technologies are available to minimize its noise.

Vehicle size is important for the following reasons:

The Wankel type rotapower® engine developed by our company for the Skycar is a four-stroke engine. The combustion chamber shape allows a richer fuel-air mixture to be present near the spark plug and a much leaner (oxygen rich) mixture to exist over much of the remainder of the combustion chamber. The resulting lean mixture has enough excess oxygen to essentially eliminate unburned hydrocarbons and carbon monoxide. NO_x formation is low in the rotary engine because peak combustion pressures and temperatures are lower. The rotapower® engine’s ability to meet the California Ultra-Low Emissions Vehicle Standards (ULEV) without exhaust after-treatment has been authenticated by the Institute of Transportation Studies (ITS)⁽⁸⁾.

The most friendly element of the Skycar is its potential to eliminate a major portion of the over 40,000 annual deaths on the highways of America. These deaths are mostly due to inexperienced drivers, drugs, drowsiness or excessive speed. Figure 6 shows the pre-retirement years of life lost due to the three major killers--motor vehicle crashes, cancer and heart disease.

Motor vehicle crashes remain the leading cause of death for Americans until their mid-thirties except for the very youngest children. Unfortunately alcohol related crashes still account for 41% of all people killed in highway accidents. With the Skycar operating in an automated flight control mode the occupants could, due to any of the above, end up in the wrong city by coding in the wrong destination but they will arrive safely.

Figure 6. Pre-Retirement Years of Life Lost by Age 1992

Other elements that enhance the Skycar’s user friendliness include:

For volantors to be deployed in numbers high enough to significantly impact personal transportation they will need to operate on a precisely defined and monitored set of airways. The  volantor must be fully automated in its flight without the option for the pilot to provide flight path input. The ability to follow a prescribed airway can be achieved entirely on-board the volantor through the use of information similar to that provided by an upgraded version of the GPS guided moving map displays available for your automobile. That information would then be used to automatically control the volantor’s flight along the pre-determined flight path to your destination.

The present United States GPS and the proposed European Galileo System could be linked to provide a global navigation satellite system GNSS. These 50-to-60 satellites would be combined with a regional geo-stationary satellite to form the Wide Area Augmentation System (WAAS) with a position accuracy of 7 meters horizontally and vertically. Local Area Augmentation Systems (LAAS) near airports, vertiports, etc. can increase this accuracy to within inches, but while attractive, is unnecessary in our view for projected large-scale volantor use.

In 1999 the FAA commissioned Phase I of WAAS for operational use in the U.S. national airspace. Phase II and Phase III will be completed by 2001 and will allow GNSS to be used as a primary navigation aid for all phases of flight down to and including Category I precision approaches⁽⁹⁾. The second element required for safe flight is a proximity measuring system on the volantor that monitors and maintains the appropriate separation distance between volantors on the same airway. This proximity warning system would also provide a back-up warning system should any nearby aircraft fail to maintain its prescribed path or distance. Finally, automatic dependent surveillance (ADS) will let a central monitoring center know where your volantor is relative to where it should be in relation to every other aircraft in the area and impose corrective action as required.

While the volantor operator must have little to no discretionary power to alter the prescribed path, he can of course change his mind and ask central control to be re-routed to a different destination. Route changes would occur near airway intersections in manner not unlike highway intersections. Considering that all volantors on one airway are moving at the same speed and direction, the physical constraints should be modest while the visual activity as perceived by the volantor occupants could be quite benign.

It is anticipated that significant numbers of landing or take-off sites called vertiports will be present in or near every major city. Japan, for example, has plans to build 3600 vertiports⁽¹⁰⁾ (presently called heliports). Availability of a larger number of landing sites will ensure that fueling and maintenance can be provided as part of a local take-off routine. Since the length of a scheduled flight is known before take-off and the option to divert is under central control, the possibility that the volantor will run out of fuel is eliminated. The Skycar volantor uses an engine that can burn almost any fuel from diesel to natural gas so that worldwide refueling can be accommodated by what is locally available. Except for engines, the Skycar has few components to wear out. The engines in long block form weigh less than 80 pounds, occupy less than one cubic foot and can be comfortably handled by, for example, United Parcel Service should the need to ship to a service center arise. The bulk of the remaining technology is electronic and would be replaceable in modules as the on-board redundant systems identify a failed or failing component. These electronic components could be available at the vertiport along with, perhaps, replacement engines for non-scheduled maintenance.

Automobiles in one form or another are here to stay. What we need is a convenient alternative for a large portion of the inconvenient trips made by the automobile. Available data⁽¹¹⁾ suggests that 85% of automotive miles traveled annually are for round trips longer than 100 miles. If the cost-effective volantor is used only for these longer trips it would have an enormous impact on traffic near cities which are usually the departure or arrival point.

Today people use commercial air travel because of the time required to undertake longer trips by automobile. With flight speeds potentially five times faster than the automobile, the volantor can expand our personal travel freedom enormously. This travel alternative will off-load much of existing airport traffic so that commercial air trips of 1000 miles or more can become time efficient.

The volantor could also affect the life-style in and around cities since the willingness or unwillingness to commute determines where many people reside. If living 100 miles away is only a 20-minute commute, the demographics near and within cities are likely to substantially change. It might be argued that one could sell his high priced apartment in San Francisco, use the proceeds to purchase a volantor (hopefully a Skycar) and an estate on the side of a mountain, and still retain a substantial amount of money.

In an automated airway network described here, with the human out of the volantor flight control loop, a large portion of the 40,000 yearly highway deaths could be eliminated.

The technical feasibility of this alternative form of transportation has been verified by a lengthy study of the volantor design by Boeing Aircraft Company. It is unlikely, however, that Boeing or any other company is going to embark on a major effort to develop such a vehicle until a lead government agency commits itself to provide complimentary support. This is because the airway infrastructure is so critical to the ultimate success of this form of transportation, and aeronautical infrastructure is developed and run by the government.

The volantor approach to dealing with personal mobility will require a paradigm shift in both government and industry thinking. Unfortunately, the logical government agency, NASA, has moved away from aeronautical research, which historically was their mandate. Once we decided to put a man on the moon the majority of NASA’s budget went into space and stayed there. Today aeronautical research makes up less than one fifteenth of 1% (.06%) of the NASA budget.

We have a problem on our highways and at our airports that is going to get much worse before it gets better, even if NASA and industry immediately begin directing more of their talent and money there. While we delay, experienced aeronautical engineers are retiring and new ones are not finding jobs in their field.

For example, while teaching at the University of California, Davis, in the 1960 ’s, I developed the only aeronautical engineering curriculum that still remains in place within the U.C. system. Subsequent lack of government/industry support for aeronautics has made it problematic to issue an aeronautical engineering degree. Instead, U.C. Davis now provides a joint mechanical/ aeronautical degree to ensure employment opportunities. If government and industry do not act quickly there will be no experienced aeronautical engineers available when we finally decide to address this earth-bound and near earth transportation problem.

We are developing wonderful forms of telecommunications and we are going to need them. At this rate, we will be doing much of our work either from airports or from our cars, while we sit waiting for a solution to a growing transportation crisis.