🚀 go-pugleaf

   Did anyone see the article about the Moeller flying car in Popular Science last
   year? Supposedly Moeller has been working on this flying car which hovers as
   well as travels 300mph+. If I recall he had developed a lightweight rotary 
   engine just for this application. The vehicle was computer controlled and
   guided by a single joystick. Supposedly the average person could pilot the 
   vehicle with little or no training. The article showed an actual working
   prototype which hovered with Moeller in it (a crane was used as a safety
   net). For mere $100,000 you can reserve yourself a complete vehicle. I believe
   he used four engines. For what its worth.

Ah, the old DiscoJet.  Moeller used to teach at my alma matter (UC Davis),
before leaving to work on exhaust systems for vehicles and this flying car.
The flying car work is (I understand) funded by the exhaust systems (you may
have heard of Super-Trapp).  There are some interesting technical problems
associated with building such a flying vehicle, most of them having to do
with the control problem:

  1. The configuration is inherently unstable (like a helicopter).  Since
     there is no large rotor to slow the natural frequency of response, it
     is my guess active computer control is required to keep it from
     flipping over once the vehicle is out of ground effect area.

  2. What level of computer control redundancy is required?  What does all
     this fault-tolerant avionics cost?  How will the manufacture ever
     afford liability insurance (a substantial component of today's
     astronomical light aircraft prices)?

  3. In hover mode at altitudes above those where ground effect is useful,
     it will be difficult to get a high enough dPower/dTime to make for
     effective control.  Note that a fixed wing aircraft uses it's KE
     (ailerons against the slipstream) to get the higly controllable power
     necessary to maintain stability in turbulent air.  Helicopters have a
     large spinning wing, whose pitch is changed quickly.  Here, again,
     instantaneous manuevering power is provided by stored energy (this time
     the inertia of the rotor) rather than modulation of the prime mover.
     The two methods likely to work for the Disco Jet are either vectoring
     the thrust (but this is hard to make efficient), or variable pitch
     fans/propellors and governed engines.

  4. What is the fuel consumption?

- Bart