Re: NASA High-Malarkey Project

[John Denker <jsd@MONMOUTH.COM>]

At 09:18 AM 9/19/99 -0500, brian whatcott cited the following as an example
of a NASA High-Risk Project:
> personal flying machine, which can be
> seen on the company's Web site at www.solotrek.com. Plans call for it
> to go up to 80 mph, climb as high as 10,000 feet and get about 20
> miles per gallon of regular gasoline.
>
> http://www.infobeat.com/stories/cgi/story.cgi?id=2561173967-b7a


Some thoughts:

1)  NASA is not homogeneous.  I've known a few truly brilliant, dedicated
people who worked for NASA.  I've also seen a few mindless time-serving
bureaucrats engaging in petty corruption.

2) There's no doubt that a personal VTOL device can be built.  I have
literally had my hands on a Rocket Belt that was still warm from being used.

3) The Solotrek web page makes a number of highly implausible claims.

  a)  For starters, I want to know how they created an internal-combustion
engine that doesn't have intake valves or exhaust valves.

  b)  They appear to be exaggerating the gas mileage by a large factor
(somewhere between 200% and 1000%, depending on how much credit you give
them for solving hitherto-unsolved problems).
  -- This is based on simple formulas from e.g. Stepniewski and Keys
_Rotary Wing Aerodynamics_ for the minimum physically-possible energy per
unit momentum (i.e. minimum power per unit thrust).
  -- Also by way of comparison, note that a Robinson R22 (a very small
helicopter) can get about 12mpg... using a much larger (and therefore more
efficient) rotor.

  c)  They appear to be wildly exaggerating the claim of safety in several
ways:
   -- They say that the thing flies even after a total electrical failure.
This tells me it can't depend very much on fly-by-wire technology.
Elsewhere they say that it "has been designed to prevent the operator from
endangering himself/herself or others, either on purpose or by accident."
Not even on purpose?  Really?  That requires an unprecedented level of
cybernetic control.
  -- They argue that any engine failure would most likely be confined to
one of the four cylinders.  What they don't seem to realized is that even a
25% power reduction would most likely to be fatal.  Given their claimed
rated engine power, and again using the power-required formulats from
Stepniewski and Keys, they don't have enough excess power.  Basically, the
rotor isn't big enough.  And they appear to have made no provision for
autorotation -- which is how real helicopters cope with power failure.

4) More generally, my BS-detector is pegged for the following reason:

In the lab where I work, everybody is trained to make intelligent
tradeoffs:  high risk is not justified unless the potential payoff is
correspondingly high.  If there is an option to reduce the risk and/or
increase the payoff, take it!

Now consider the Solotrek device.  Never mind the rotor etc., just consider
the engine.  Everybody knows that 2-cycle engines have an obvious advantage
in power-to-weight performance.  The essential drawback is fuel efficiency.
 So if the Solotrek folks really have a reliable 2-cycle engine with
*better* efficiency than anything the transportation industry has ever
known, why are they wasting it on this unusual application?  Why not take
the engine and stick it in existing airplanes -- and existing cars as well?

In short, in the language of game theory, their current strategy is
Pareto-inferior.

I'm all in favor of high-payoff projects, and I'm willing to run high risks
when that's what's needed.  But let's not pretend that high risk is
meritorious.  Risks are like potholes in the road.  We steer around them
when we can.