Propulsion and Wing Placement
Country: United States
Date: May 2006
Does the propulsion type of an aircraft have any
effect on whether the wings are on top or bottom of the
aircraft? Specifically, are all jets bottom winged?
Actually, no. Take, for example, the C-141, C-5, and C-17 cargo
planes. They are all High wing jets. The arrangement of aircraft
components is actually determined at design by several factors. Most
important of which is "what mission is this aircraft going to have to
perform most of the time?" After a bit of study, you begin to notice
that aircraft that fly similar missions look similar. It is one aspect
of "form follows function."
Some short examples: The cargo planes mentioned above are high wing
primarily to make loading and unloading of cargo easier by getting the
fuselage as low as possible. Fighter planes are usually mid wing with
little or no dihedral to have neutral stability. This increases
maneuverability. Engines placed above the wing (like on honda's jet),
reduce FOD damage to the engines (arguably the costliest single
replaceable component of an airplane) and place the fuselage closer to
the ground to make it easier to get in and out.
There is much more to it that there is not room to go into here. Check
out the book "The Anatomy of the Airplane" by Darrol Stinton at
http://www.aiaa.org/content.cfm?pageid=360&id=567 if you are interested
in learning more about why aircraft look the way they do. It is the
only resource I know that goes into it in detail.
David Brandt P.E.
On a simple level, there is no relation between propulsion type and
wing placement. On a slightly more involved level, the only
relation is allowing a clear area for the engines, which does not
interfere with airflow over the wings. Thus, you may place the
wings of an aircraft near the bottom, top, or middle of an aircraft
regardless of what moves it through the air.
Many fighter jets feature wings mounted near the middle or top of
the aircraft, while a great majority of large commercial aircraft
have thier wings mounted quite low. In both cases, a strong
argument may be placed on the accesability of the wings as a cause
for wing placement. Maintenance crews for combat aircraft need to
be able to get under the wings to attach weapons and sensor pods,
while much larger commercial airliners need thier wings mounted low
so the engine pods themselves will be within reach for ground crews.
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Update: June 2012