The Wainfan FMX-4 Facetmobile is an American

homebuilt aircraft Homebuilt aircraft, also known as amateur-built aircraft or kit planes, are constructed by persons for whom this is not a professional activity. These aircraft may be constructed from "scratch", from plans, or from assembly kits.Armstrong, Kenn ...

Northrop Grumman Northrop Grumman Corporation is an American multinational aerospace and defense technology company. With 90,000 employees and an annual revenue in excess of $30 billion, it is one of the world's largest weapons manufacturers and military techn ...

aerodynamicist and homebuilt aircraft engineer. While only one Facetmobile prototype was produced, it has become well known due to its unique nature. The aircraft is unusual in that it is a

lifting body A lifting body is a fixed-wing aircraft or spacecraft configuration in which the body itself produces lift. In contrast to a flying wing, which is a wing with minimal or no conventional fuselage, a lifting body can be thought of as a fuselage wi ...

– the whole aircraft acts as a low aspect ratio

wing A wing is a type of fin that produces lift while moving through air or some other fluid. Accordingly, wings have streamlined cross-sections that are subject to aerodynamic forces and act as airfoils. A wing's aerodynamic efficiency is expres ...

: a flat, angular lifting shape, unlike traditional aircraft which use distinct lift-generating wings attached to a non-lifting fuselage.Barnaby and Lynn Wainfan's Facetmobile page
accessed October 24, 2006 Also notably the aircraft's shape is formed of a series of 11 flat surfaces, somewhat similar to the body of the

F-117 Nighthawk The Lockheed F-117 Nighthawk is a retired American single-seat, twin-engine stealth attack aircraft developed by Lockheed's secretive Skunk Works division and operated by the United States Air Force (USAF). It was the first operational airc ...

jet strike aircraft in using flat plates, but without separate wing structures. Although aerodynamic efficiency is reduced due to the simplistic shaping, that shaping reduces structural weight, improving payload mass fraction.

Design and development

Shape

The FMX-4 Facetmobile shape forms 11 flat planes, plus two wingtip rudders. Three flat shapes form the bottom of the aircraft (slightly inclined front, flat middle, and sharply raised back), and eight form the top (one large downwards-sloping rear section, one thin nose section, and three inclined side panels per side). The wing section is an 18% thickness ratio, much thicker than the typical 12-15% thickness of normal light aircraft wings. At least one commercial model airplane kit of the Facetmobile is in production. The prototype FMX-4 Facetmobile crashed on October 13, 1995, after an in-flight engine failure. The aircraft landed at low speed into a

barbed wire A close-up view of a barbed wire Roll of modern agricultural barbed wire Barbed wire, also known as barb wire, is a type of steel fencing wire constructed with sharp edges or points arranged at intervals along the strands. Its primary use is t ...

fence, which caused extensive skin, engine, and some structural damage, though there was no injury to the pilot, Barnaby Wainfan. As of 2006, the aircraft has been partially repaired but not flown again.

Structure

The Facetmobile structure is composed of

6061 aluminum 6061 ( Unified Numbering System (UNS) designation A96061) is a precipitation-hardened aluminium alloy, containing magnesium and silicon as its major alloying elements. Originally called "Alloy 61S", it was developed in 1935. It has good mechani ...

tubing fastened with Cherrymax rivets. The fuselage uses conventional fabric covering. The aircraft uses

elevons Elevons or tailerons are aircraft control surfaces that combine the functions of the elevator (used for pitch control) and the aileron (used for roll control), hence the name. They are frequently used on tailless aircraft such as flying wings. A ...

and rudders for control. The landing gear is a fixed tricycle type. The large windshield sections are augmented by two floor-mounted windows. The aircraft is boarded through a bottom-mounted hatch. The aircraft has a BRS parachute system installed.

Variants

Wainfan has proposed two derivative aircraft based on the FMX-4 Facetmobile. * FMX-5 Facetmobile, a larger 2-seat design using the same aluminum-tube-and-fabric construction. * An unnamed similar 2-seat design using advanced flat composite panel construction.NASA LARC NAG-1-03054 "Feasibility Study of the Low Aspect Ratio All All-Lifting Configuration as a Low-Cost Personal Aircraft"
Barnaby Wainfan and Hans Neiubert, February 2004, accessed October 24, 2006

Specifications (Facetmobile FMX-4)

References

External links

{{Commons category, Wainfan Facetmobile
Barnaby Wainfan's website
accessed October 17th, 2022.
Quarter scale Facetmobile
Youtube clip of a radio-controlled model. 1990s United States civil utility aircraft Homebuilt aircraft Lifting bodies Aircraft first flown in 1993 Single-engined tractor aircraft