"David Lednicer" wrote in message
...
I've got to disagree with your assertion that canards are good for
range. I worked on the Voyager, Starship, Triumph, Catbird, ATTT, Ares
and JetCruzer, plus I've analyzed the VariViggen, VariEze, Long EZ,
Solitaire, Defiant, Predator, Quickie, Q2 and Dragonfly post-facto.

To get long range, you want to fly at a speed slower than maximum, near
or at the best L/D point. This involves flying at a higher lift
coefficient and the induced drag becomes more important here. To get
low induced drag, you need the sum of all lifting surfaces to have an
elliptical lift distribution. The canard will by itself be nearly
elliptically loaded. The aft wing, of greater span, will then need a
hole in its lift distribution inboard to accomodate the canard's
loading. This means that the inboard aft wing will be carrying little,
if any, loading. However, it will physically be there, causing profile
drag - a horse that is eating, but not pulling. Even worse, on a
canard, you want the fuel on the CG, so as it is used, the CG won't
shift. This means real big strakes on the aft wing usually. Thus, the
part of the wing contributing profile drag, but no lift, gets even
bigger. For a given L, the D has now been forced to get much bigger,
clobbering L/D.

The induced drag efficiency ("e") of the Voyager was around .5, as
opposed to .75-.8 on conventional configurations. Simply put, the
Voyager could have gone around the world with less fuel if it had been
conventionally configured. The reason that the Voyager is in the
Smithsonian is that Dick, Jeana, Burt and the rest of the crew created
an airplane and performed a mission that no one had ever performed, plus
many had dreamed of.

Yes, the Long EZ has good range. However, a conventionally configured
aircraft of the same GW, with the same engine and fuel quantity would
have longer range. For the same L, the D would be lower.

Absolutely agree.

Burt Rutan once designed a canard sailplane where L/D is paramount called
the Solitaire. It was a miserable failure. Conventional designs of the
same span, weight and general fit and finish, had much more performance.
(And, if powered, would have more range.) In a sailplane, there is nowhere
for the designer to hide - aerodynamic problems are plain for all to see.
More power and less weight can hide aerodynamic problems in powered
aircraft, but not in a sailplane.

For me, the Solitaire drove the final nail in the canard's coffin. In
addition to poor aerodynamics, canards have poor TO and landing performance,
suffer from FOD, and have a notably worse safety record than conventional
airplanes. They are an all-round bad idea.

Bill Daniels