Introduction:
The wing spar in a Cessna 152 is a structural component that runs through the length of the wing
and provides the primary support for the wing. It is designed to carry the weight of the aircraft and
the stresses generated by flight, such as lift and aerodynamic forces. The wing spar is typically made
of high-strength materials, such as aluminium alloys or composite materials, and is reinforced at
critical points to ensure its strength and durability. In the Cessna 152, there is one main spar that
runs through the centre of the wing and two auxiliary spars that support the wing flaps. The wing
spar is a crucial part of the aircraft's structure and is carefully inspected and maintained to ensure
the safety of the aircraft and its occupants.
C-Beam Wing Spars:
C-beam wing spars are a type of wing spar that are commonly used in aircraft wings. The name "Cbeam" is derived from the shape of the cross-section of the spar, which resembles the letter "C". The
C-beam spar design has two flanges and a web between them, forming a rigid and strong structure.
The flanges provide the required strength in compression and tension, while the web provides the
required stiffness.
Advantages of C-Beam Wing Spars:
High Strength to Weight Ratio: C-beam wing spars have a high strength to weight ratio, meaning
they provide the required strength while keeping the weight of the wing structure to a minimum.
This results in improved aircraft performance, as lighter structures result in reduced fuel
consumption and improved manoeuvrability.
Increased Stiffness: The C-beam spar design provides increased stiffness compared to other wing
spar designs. This results in improved wing stability and reduced wing deflection during flight.
Improved Fatigue Resistance: C-beam wing spars have improved fatigue resistance compared to
other wing spar designs. Fatigue resistance is important in aircraft design, as the wing spars are
subjected to repeated loading during flight, and any failure of the wing spar can result in a
catastrophic failure of the wing.
Ease of Manufacture: C-beam wing spars are relatively simple to manufacture, as they can be made
using a variety of materials and fabrication techniques. This results in reduced manufacturing costs
and improved production efficiency.
Disadvantages of C-Beam Wing Spars:
Increased Cost: The C-beam wing spar design can be more expensive compared to other wing spar
designs, as it requires more material and fabrication time.
Limited Space: The C-beam wing spar design can be limited in terms of the space available for wing
systems and equipment, as the web of the spar can take up valuable space in the wing structure.
Comparison with I-Beam Wing Spars:
I-beam wing spars are another type of wing spar that are commonly used in aircraft wings. The name
"I-beam" is derived from the shape of the cross-section of the spar, which resembles the letter "I".
The I-beam spar design has two flanges and a web between them, similar to the C-beam spar design.
However, the I-beam spar design has a more slender web compared to the C-beam design, resulting
in a different set of advantages and disadvantages.
Advantages of I-Beam Wing Spars:
Reduced Cost: The I-beam wing spar design can be less expensive compared to the C-beam design,
as it requires less material and fabrication time.
Increased Space: The I-beam wing spar design provides more space in the wing structure compared
to the C-beam design, as the web of the spar is more slender. This results in more space available for
wing systems and equipment.
Disadvantages of I-Beam Wing Spars:
Reduced Strength to Weight Ratio: I-beam wing spars have a reduced strength to weight ratio
compared to the C-beam design. This means that the wing structure will be heavier, resulting in
reduced aircraft performance and fuel efficiency.
Decreased Stiffness: The I-beam wing spar design provides decreased stiffness compared to the Cbeam design. This results in increased wing deflection and reduced wing stability during flight.
Decreased Fatigue Resistance: I-beam wing spars have decreased fatigue resistance compared to the
C-beam design. This means that the wing spars may be more susceptible to failure due to repeated
loading during flight.
Conclusion:
In conclusion, the choice between C-beam and I-beam wing spars depends on the specific
requirements of the aircraft design. C-beam wing spars provide high strength to weight ratio,
increased stiffness, and improved fatigue resistance, while I-beam wing spars provide reduced cost
and increased space. Both designs have their advantages and disadvantages, and the optimal choice
will depend on the trade-off between these factors for the specific aircraft design.
It is important to consider all factors when choosing between C-beam and I-beam wing spars,
including the weight and performance requirements of the aircraft, the cost and production
efficiency of the wing spar design, and the availability of materials and manufacturing techniques.
Ultimately, the choice of wing spar design will have a significant impact on the overall performance,
safety, and reliability of the aircraft.
Cessna Wing Spar specifications:
The Cessna 152 has one main wing spar that runs through the centre of the wing, and two auxiliary
spars that support the wing flaps. The Cessna 152 has one main wing spar that runs through the
centre of the wing, and two auxiliary spars that support the wing flaps.
The main wing spar is the primary load-bearing member of the wing structure and is responsible for
carrying the weight of the aircraft as well as the stresses generated during flight. It is located at the
midpoint of the wing and extends from the fuselage to the wingtip.
The auxiliary spars are located closer to the wingtip and provide additional support for the flaps,
which are movable surfaces that help to control the aircraft's speed and descent rate during landing.
The auxiliary spars are not load-bearing members of the wing structure like the main spar, but they
do help to distribute the loads more evenly across the wing.
For the main spar the Cessna 152 uses a c beam type wing spar that is 8.28 meters long, and has a
rectangular cross-section with dimensions of 10 cm by 7.6 cm. The spar is made of high-strength
aluminium alloy, typically 2024-T3 or 7075-T6, and is reinforced with several ribs and stringers to
distribute the loads evenly along the length of the wing. The weight of the Cessna 152 wing spar
depends on the materials used in its construction, but typically it weighs around 85-95 pounds (3843 kg).
As the Cessna uses one main wing spar at a size of 8.28 meters for my calculations I will use a size of
4.14 meters and a weight of 20kg, I am doing this as all calculations were performed using the
concept of cantilever beams.