Hangar Talk 1: Of Boats, Planes and Flying Wings

Standing in the hangar today, I was deeply engaged in a discussion with another pilot about the pros and cons of current aircraft design. We both agreed that designers have pretty much maximized the efficiency of the fuselage/wing method. Any further increases will come from add-ons like winglets, sharklets, alligatorlets, or whatever other things they come up with to slap onto the end of a wing. Therefore any radical increase in payload or range will have to come from a radical change in construction.

Before everyone throws down their copy of Controller and spills coffee in a rage at my upstart attitude, consider that almost all respected designers as recent as the 1990s regarded winglets as a fashion statement added by the marketing department. In 2007, the last true defender of “build the wing right the first time”, Dassault Falcon has finally and begrudgingly added winglets to their aircraft. It took a massive increase in fuel prices to force a change in perspective but everyone eventually came around. It will be much the same with a new type of aircraft design. Don’t worry, you’ll get used to it.

Lifting body/flying wing/blended wing body designs are among the most efficient shapes in the sky. All fighter jets from the 4th generation onward have lifting body tendencies. That’s why an F-4 Phantom’s turn radius makes F/A-18 pilots start laughing uncontrollably…the F-4 was a brute force airplane: Fuselage, intake/exhaust, wing, stabilizers and engines. The F/A-18 had and still has leading edge root extensions (shortened to LERX to prevent pilots from having to say “My plane has ‘stensions!”). At higher angles of attack, they begin producing powerful vortices that drift over the top of the wing and delay the stall far beyond what would be expected from looking at the airfoil’s lift curve graph.

McDonnell Douglas F/A-18F Super Hornet pulling into a square loop, showing the powerful LERX vortex generated from the increase in angle of attack.
(I know Boeing bought out McAir but it just doesn't sound right even today)

But there is part of the problem. In order for the LERX to work, it needs to be at a fairly steep angle of attack. High angles of attack and normal landing gear aren’t friends. The result is a long, ungainly set of gear so the aircraft can rotate to a useful pitch angle, or a set of regular gear that will require delaying takeoff to a higher speed, which negates one of the reasons for generating more lift in the first place. Also little tidbits like being able to see over the nose and not scraping the tail on the runway are important as well. These will have to be addressed before any alternative design can be taken seriously.

In the air, the problems begin to vanish as the advantages outweigh the disadvantages (depending on how fast, high and aggressively you’re flying). One major disadvantage is the volume requirement for flying wings. A pure flying wing encompasses everything inside the wing. In order for this to happen, the wing must be very large. Think YB-49 large. Otherwise, it will be a not-so-pure flying wing, which is not a bad thing (blended wing body or BWB). The B-2 Spirit stealth bomber really is a BWB as the cockpit and intakes protrude above the upper surface of the wing. The thickness to chord ratio would have been prohibitively large in order to fit the cockpit inside which would have reduced maximum speed. The really nice thing is that the “fuselage” on the B-2 does not need the normal streamlining since only a portion of it is in the airflow. The part that’s buried in the wing can be whatever dimension the designer desires.

Okay, back to the hangar conversation. My stance was that normal airplanes waste a lot of energy lifting parts they don’t need to lift. If I’m on a boat, I sit on the deck which is covering the hull. The hull is the only part that moves through the water. There is no heavy, non-buoyant passenger cabin supported by hulls on the port and starboard like poorly designed pontoons. Even catamarans keep their center sections out of the water (it would cause an incredible penalty in drag to have it actually in the water). And yet that’s how we build airplanes, with non-contributing sections in the airflow. The other pilot (who occasionally goes out in boats) understood immediately. We have to be able to put almost everything inside the wing, or make most of the fuselage into a wing in order to make it work more efficiently for us.

Vincent Burnelli, John Northrup and Charles Zimmerman laid the ground work in the early 20th century. Designers that followed have taken bits and pieces from their discoveries but few if any have been able to put them together in a way that was commercially viable, useful and safe for the civilian market. There is no reason that people can’t be flying around in a 4 seat airplane that burns 8 gallons per hour, lands at 50mph and cruises at 200mph. There is no reason why people can’t be surrounded by a steel safety cage much like the one utilized in Barnaby Wainfan’s Facetmobile to protect them in the event of an accident. We just have to readjust our perspective as pilots, designers and as people and ask what can be instead of what will never be.