The Explorer Design
When Graham Swanell designed the Explorer he wanted the best of both worlds-- high speed flight and short field abilities from the same wing. He wanted ample fuel volume and light structural weight, which require a thick airfoil.
So, when Graham formed the design group for the Explorer, he chose John Roncz of the United States, to do the wing aerodynamics. John, a well-known and respected aerodynamicist, had been involved in several cutting-edge aircraft designs, including the Voyager and Global Flyer, both record setting aircraft.
About the Wings
Graham also desired a wing with low drag, which would require a thin airfoil. Adding to these almost impossible requirements, he wanted good climb rate requiring a long wing and the good roll rate of a short wing.
Fortunately, John had some secret weapons up his sleeve. He had been working on airfoils for flying wings for about ten years. He had also designed and flown wings with forward sweep. This experience would be brought into play in the design of the Explorer wing. The wing of the Explorer may look traditional but if you take a closer look you will see a pretty amazing airfoil.
"This design has the potential of fantastic maximum lift with flaps."
The wing has relationship to the Grumman X-29 and the Northrop Grumman B-2. Two principles of aerodynamics are involved, forward sweep, as with the X-29 and the flying wing being used for the B-2.
John wanted to start with a stable airfoil. "Stable" means that as the angle of attack increases, the airfoil will create forces which push the nose back down, and when the angle of attack decreases, the airfoil will create forces which push the nose back up. This stability does have a penalty in design -- it loses some maximum lift. John has been able to overcome these two inherent penalties by finding a way to create stable airfoils with extraordinary maximum lift. He has also discovered a way to make thick airfoils have the drag of thinner airfoils.
These design features were incorporated into the Explorer wing. This design has the potential of fantastic maximum lift with flaps. A high lift flap was created which resulted in a wing with a maximum lift coefficient of 2.5. This number may seem insignificant until it is compared with other aircraft. The maximum lift coefficient of a King Air with full flaps is 1.8. The Explorer wing has a 39% improvement. This allows the wing area to be reduced for the same stall speed. Through research, it has been found that the forward sweep of wings protects the airflow over ailerons, so at stall the ailerons remain fully effective. This technology was transferred into the Explorer wing. The outer wing panels have an aft-swept leading edge and a forward-swept trailing edge, which gives it forward-swept ailerons.
"The Explorer wing has a 39% improvement in maximum lift coefficiency compared with other aircraft."
Additionally, this tapering of the outer wing panels gives the wing a more elliptical shape; ideal for minimizing the induced drag of the wing and this shape improves roll rate for the Explorer. The outer wing panels also have more dihedral which gives the entire wing increased effective dihedral. The Explorer wing has met all of the aerodynamic design criteria. Additionally, with its thick wing it has room for adequate fuel for long range missions. Struts were used to save on structural weight and to allow for a smaller carry-through spar in the cabin. This in turn saves headroom space in the cabin.
(CFD computer model accurately representing the flow patterns around the body.)
Patented Landing Gear
The retractable landing gear system for the Explorer is very unique. Explorer was designed to be a working airplane so we listened closely to cargo and passenger service operators who wanted a low cabin entry height as well as large flat cabin floor. The result was a design that achieves both goals and provides a very strong structure with a wide stable stance. The hydraulic gear has three levels of redundancy for safety and still supports a very large tire for rough field use.
View the full detailed patent in PDF
Also, see the gear in action in our media section.
Explorer will also offer a fixed gear version as well as a float version in the near future.