If quoting a AIAA published textbook is not enough...
@ notes to Daniel's theories:
1. If they are draggier why can they be so much more efficient? Never hear of 50 mpg in other common designs. How many O-235 planes have flown from Phoenix to a couple hundred miles further than Oshkosh, then back to Osh on one tank of 50 gallons? A Varieze does it every year.
2. If the main wings must be so huge, why does a Varieze have such tiny wings?
3. With all that 'drag' inherant in the design how can just a smaller nose counteract it all?
4. Cooling drag can be equal given the amount of effort put into the design. They also have had good luck with plenums, downdraft, etc. When the main inlet is a NACA and the flow through the cowls is measured, as many have, the drag is as good or better than 'most' traditional designs, which of course, can also be improved.
Just sayin'......
OK, say you don't buy into all the ideas of Dr. Raymer and published as a well regarded textbook by the American Institute of Aeronautics and Astronautics. Experts are often wrong. Lets look at trends in Burt Rutan's designs. Have you ever noticed that as Rutan's designs evolved, the canard got bigger, and then eventually disappeared? After Voyager and Proteus, the canard disappeared. White Knight, Global Flyer, and White Knight II do not have canards. It appears that Rutan now agrees with what Dr. Raymer presents.
Back to the original post, lets look at the numbers. Compare the Velocity XL-FG with a Lyc IO 540 260HP engine and fixed gear to a RV-10 with the same engine. From their websites (converted to common units):
Category ---------------------Velocity XL-FG ----RV-10
Empty Weight ---------------1700 lb------------1630
Gross Weight-----------------2800 lb------------2700 lb
Useful Load-------------------1100 lb------------1070 lb
Wing Area--------------145 ft^2 combined------148 ft^2
75% Cruise Speed------------201 mph----------197 mph
Takeoff Distance--------------1400---------------500
Landing Distance-------------1500---------------650
Stall (min) speed-------------75 mph------------63 mph
So an RV-10 is :
>
lighter by 70 lbs despite having more wing area and mostly metal.
>It carries only 30 lbs less.
>Flies 4 mph slower at cruise despite having a high drag hershey bar wing optimized for metal kit building.
>12 mph slower stall (minimum) speed
>Takes off in 1/3 the distance and lands in less than 1/2 the distance.
The Velocity does have a +9g/-7g airframe, tested to +6 only. But for normal operations that just means the airframe is overweight.
Anecdotally, if canards were the marvel of efficiency, why are not all competitive sailplanes configured as canards?
There is an understated genius behind Van's "Total Performance" concept.