Aircraft Design Flashcards
Thickness in the wing is?
The distance between the upper surface and the lower surface
If engineers are designing an aircraft that will travel to multiple airports, then they have to make sure the _______ doesn’t exceed those airports
wingspan
What is load?
The force that deflects flight and produces stress on the aircraft
Engineers must optimize safety designs for _______
bird strikes, turbulence, storms, and human errors
Stability is the aircraft’s _______
inherent ability to regain equilibrium after it has been disturbed. The stability must also be done by the pilot
Flight axes are imaginary _______
lines in which an airplane can turn around.
There are 3 flight axes:
lateral axis, longitudinal axis, and vertical axis
Lateral axis is _______
an axis that runs from one wing tip to the other, and turning around this axis is called pitch. This is the most affected axis
The stability of the lateral axis is called
longitudinal stability.
Longitudinally unstable aircraft are _______
difficult and often dangerous to fly. An aircraft that is longitudinally unstable can make deep dives or climbs which could cause a stall.
Longitudinal axis is the axis that _______. Turning around this axis is called _______. The stability of this axis is _______, and lateral instability can cause _______.
runs from the nose to the tail of an aircraft
roll
lateral stability
rolls
Vertical axis is the axis that _______. Turning around this axis is called _______. The stability of this axis is called _______, which is _______
runs down through the aircraft perpendicular to the wings and fuselage
yaw
directional stability
easy to achieve because of the vertical fin and fuselage design.
Sweepback:
the backward slant of an airplane wing.
Keel effect is when the weight _______
acts as a pendulum and swings the aircraft back into position when the relative wind disturbs lateral stability. This mostly affects high wing aircraft since they have a large keel area.
Keel area:
the area of the fuselage where the relative wind can affect lateral stability
There are advantages and disadvantages to both high wing and low wing aircraft. _______
The higher the wing, the less need for dihedral. The higher the wing, the easier it is to fly the aircraft because of the increased stability due to the improved pendulum effect.
Parasol wings:
placed on struts high above the fuselage of seaplanes, help keep the engine from water spray.
Shoulder wing:
a configuration whereby the wing is mounted near the top of the fuselage
Aircraft wings are typically made of _______
aluminum or magnesium alloy. Modern aircraft use lighter, stronger materials, such as carbon fiber
There are several wing designs such as:
rectangular, elliptical, tapered, trapezoid, delta, ogive, forward-swept, sweptback, and variable designs.
Rectangular wings are _______
straight, non-tapered, and used mostly in small aircraft. They are the simplest to manufacture, but they are not aerodynamically efficient
Elliptical wings are _______
the most aerodynamically efficient wings because they allow for the least possible amount of drag and thinness. A drawback is that they are hard to manufacture
Tapered wings are _______
similar to rectangular wings, but instead they get tapered towards the tips and allow similar lift distribution as elliptical wings. They are not as aerodynamically efficient as elliptical wings, but they are easier to manufacture
The delta wing looks like a _______
triangle, and they have a large surface area. It is mostly used in supersonic flights for supersonic aircraft, but it’s also efficient for subsonic and transonic flights. They have a high maneuverability because of their low wing loading. Delts wings are structurally sound, and they have a large area for fuel. They are also simple to manufacture and maintain. One disadvantage is that at low speeds they have a large AOA and more drag
Trapezoidal wings have their _______
trailing edge sweeped forwards and the leading edge backwards. This wing design provides great flight performance and is commonly used in US combat aircraft. They are also highly efficient for supersonic flights and have good stealth characteristics. One disadvantage is that its high wing loading decreases its maneuverability.
Ogive wings are _______
a complex and mathematically difficult design used for high-speed aircraft to reduce drag during supersonic flight. Although they have excellent performance during supersonic flight with little drag, they don’t perform well in subsonic. Because they are so intricate, they are hard to manufacture. They are often called “Concorde wings” because the retired Concorde has been the only airplane with these types of wings
Sweepback wings have the leading edge _______
swept back. They are used for less drag in transonic flight. The majority of commercial aircraft use this design because they allow for faster flight with less drag.
Forward-swept wings have the leading edge _______
swept forwards. It had controllability issues and it was only used in a few aircrafts. Although it has an unusual design, it allows for more maneuverability. It allows for a steeper angle of airflow without a stall. In WWII, Germans created this concept, but it never went past its prototype. In 1984, NASA and the Air Force partnered and made the X-29 to experiment with the design. It proved to be more maneuverable at high speeds, but the project was discontinued in 1992.
Variable wing design can use _______
combinations to adapt over different range speeds to optimize performance. For example, at high-speed flight, such as supersonic or transonic, sweepback is better. But at low speeds like subsonic, non-swept is better. A disadvantage of the design is its high mechanical complexity.
Wing loading is _______
the total weight of the airplane divided by the area of the wings. Aircraft high in wing loading sometimes need more distance for landing and take off, and they are also less maneuverable.
An aircraft high in wing loading will compensate _______
from having a smaller wing by flying faster and generating more lift that way
Supersonic:
flight at speeds greater than the speed of sound
Subsonic:
flight at speeds less than the speed of sound
Transonic:
flight at speeds just under or just above the speed of sound (700-780 mph)
Center of gravity (CG) is _______. CG is also the meeting _______. It’s important to consider CG when designing aircraft, but it is equally important to consider _______. Pilots take the load _______. An aircraft too nose-heavy or too aft-heavy is _______
the point where all of the aircraft’s weight is centered
point of all the axes
that CG will move along the longitudinal axis based on load distribution
distribution into account prior to each flight
dangerous to fly
Carry-on:
a bag or suitcase taken onto an aircraft as handheld luggage. A common sized bag for carry-on luggage is 22”x 14”x 9”. Most airlines have a carry-on weight limit of 40 pounds. International airlines may have different restrictions for carry-on luggage.
Standard weights are _______
weights that are used as a reference for measuring the weight of other objects.
In a small aircraft, pilots can easily determine the effective load balance. For example, _______
if there is one pilot, and one child and adult passenger with no luggage in the back, it would make sense to sit the child in the front and the adult back to distribute the weight evenly. But if there are 200 pounds of cargo in the back, then it would make more sense to sit the adult in front and the child back to compensate for the cargo load.
In large commercial aircraft, airlines weigh baggage as it is being _______
checked to determine the cargo weight, and standard weights are used for adult and child passengers, which also includes carry-on allowances. The weight is then entered into a computer system which calculates the CG and load distribution. The computer then generates a plan for the crew to see where to distribute the cargo. For example, the front might be filled with passengers, but the rear is empty, so the plan will specify how much should be loaded in each compartment to compensate for passenger load. After loading cargo, a load sheet is then produced to inform the pilot how the aircraft was loaded and how the CG was calculated.
CG is an important concept during flight because it is where _______
the aircraft finds balance
Center of lift (CoL) is _______
an important concept, and it is the point at which the wings generate lift. It is always aft of the CG
The CoL is also referred to as the _______. Lift would cause the nose to _______
center of pressure (CP)
pitch down because of the forward CG, but the tail balances this out by creating downward lift, which allows for level flight
G is what happens when the pilot’s body _______
is trying to go straight but the direction is constantly changing. This pushes the body outward, and this is called G-force or gravity force
G-force is a measure of _______
acceleration. Acceleration is the change in velocity over the change in time (△Velocity/△Time). Velocity is determined by both speed and direction (speed+direction). So even if the speed stays the same, direction is constantly changing, so there is constant acceleration. This outward force is called centrifugal force
Centrifugal force is expressed as a _______
multiple of G
When we roll towards one direction or the other, some of the lift is _______
pointed horizontally. That horizontal component of lift causes the airplane to turn. But in a turn condition, not only do we have to overcome weight, but we also have to overcome centrifugal force. When we change the direction of travel by adding horizontal lift, we are creating centrifugal force (our airplane wants to continue going straight ahead and that’s the force we have to overcome). So we have to overcome weight and centrifugal force in a turn. When we combine these two, we get a result in force known as the load. Because load is greater than weight, we need to produce more lift in the turn so we don’t descend. Increasing bank angle increases load, so it requires even more lift.
Descent turns to wings level also increases load because the airplane wanted to continue descending but stopped. By increasing the load factor, we increase the load our wings have to carry. We measure load factor by G forces or G’s. G’s are simply the force of gravity multiplied.
You will find the G limitations for your aircraft _______. Keep an eye on your airspeed so you don’t _______
in the POH or AFM
exceed G’s.
Load factor is important when considering wing design. _______
Load is a force on the aircraft that deflects from flight and causes stress on the aircraft. It is measured in G’s. A load factor of 3 would mean the aircraft is experiencing a total load of 3 times its weight. Not only would the aircraft experience 3 G’s, but the pilot also would.
It’s important for pilots to understand the load factor of the aircraft they are operating. _______
A dangerous load can endanger the aircraft and anyone onboard if the pilot doesn’t understand the aircraft load factor. In addition, a high load factor can also increase the risk of a stall at safe speeds.
During the design of an aircraft, the limit load factor _______
is determined, which is the highest load factor at which the aircraft won’t experience structural damage.
All aircraft are given their limit load factor under normal operations, which are _______
the operations that an aircraft normally does. For example, an acrobatic plane doing stunt operations is not normal operations for most normal aircraft.
Most airplanes can withstand more than the limit load factor _______
to account for quick landings or steep dives.
The CFR requires that airplanes can withstand up to 1 and a half the limit load factor, _______
which is referred to as the factor of safety
Load factors are determined for each _______
aircraft, depending on its operational category, such as normal, utility, or acrobatic
The FAA defines normal aircraft as:
non-acrobatic, weighing 19,000 pounds or less, and having 19 passengers or less, excluding the pilot.
Utility aircraft are the same _______
type and size as a normal, but they are approved for limited acrobatics, such as spins or steeper bank angles.
Acrobatic aircraft are the same _______
type and size as normal aircraft, but they don’t have acrobatic restrictions
Payload refers to?
the total weight of passengers, cargo, or any other objects or materials carried by an aircraft. It represents the useful or revenue-generating load that an aircraft can transport. The payload can include passengers, baggage, freight, mail, or any combination thereof. Fuel is not included. It is calculated by subtracting the empty weight of the aircraft, including fuel, and other necessary equipment, from the maximum allowable gross weight.
Newer engineering uses composites to build the fuselage, such as:
fiberglass, carbon fiber, Kevlar, cloth, or a combination. Composites are extremely smooth and easy to use, which help to make a sleek, streamlined aircraft. Carbon fiber is an extremely strong and lightweight material that helps to save fuel during flight
Weight and balance are important when considering?
the design of an aircraft. Aircraft that are overloaded have more take off speed, longer runways, lower climbing rate, more fuel burning, less range, lower maximum altitude, less maneuverability, longer landing roll, etc.
When designing and constructing an aircraft, the maximum gross weight is determined by?
calculations.
Static load is?
the weight of the aircraft itself
Dynamic load is?
the load imposed by flight maneuvers
An aircraft must be able to support static load and dynamic load. For example:
the wings of 3,000 pound aircraft must support 3,000 pounds during level flight, but on a 60 degree sharp turn, they must support 6,000 pounds of load.
It’s vitally important for the pilot to know what about the aircraft’s weight?
the current and accurate weight of the aircraft
Periodic weighting of aircraft is _______
desired, but at minimum the aircraft must be weighted after extensive repairs or maintenance.
The aircraft weight is always the _______
basic empty weight (BEW), which does not include the weight of fuel, passengers, crew, oil, or cargo.
During preflight planning, the pilot must make what about weight?
weight calculations for safe flight.
The total weight of an aircraft and where it is placed is _______
critical for flight.
When making weight calculations, the pilot must consider what weights?
the basic empty weight (BEW), weight of fuel, passengers and crew, and baggage.
A gallon of fuel weighs approximately?
6 pounds.
If a pilot needs to reduce weight, they can store _______
less fuel for flight, but the range should be considered when making calculations
Balance is the location of?
the center of gravity (CG) in an aircraft. How weight is distributed can impact the balance of the aircraft. Too much weight on the front makes it nose heavy while on the back makes it tail heavy. Unbalanced aircraft are unstable and are harder to fly for the pilot. Think of the aircraft as a teeter totter, an aircraft will fly better if it’s balanced. Many pilots will add baggage to the back to compensate for full fuel and no load on the back.
The reference datum is?
an imaginary vertical plane from which horizontal distances are measured for aircraft weight and balance purposes. The datum is determined by the manufacturer, and in small aircraft, the reference datum is often located along the firewall or at the leading edge of the wing.
During preflight planning, the pilot will calculate the CG to?
ensure weight and balance. When calculating the CG, pilots will determine the weight using aircraft weight, fuel weight, passenger weight, and cargo weight. An important part of calculating CG is understanding the datum line.
The maximum landing weight (MLW) is _______
the maximum aircraft gross weight due to design or operational limitations at which an aircraft is permitted to land. The MLW is set in order to ensure safe landings; if an aircraft weighs too heavy during touchdown, it may suffer structural damage or even break apart upon landing.
The maximum take off weight (MTOW):
The MTOW of an aircraft is the maximum mass, defined by the aircraft manufacturer (due to structural or other limits), at which the aircraft is certified for take off.
The maximum ramp weight (MRW) (also known as the maximum taxi weight (MTW)) is _______
the maximum weight authorised for manoeuvring (taxiing or towing) an aircraft on the ground as limited by aircraft strength and airworthiness requirements
The FAA requires all aircraft to carry the pilot’s _______
operating handbook (POH)
What has the datum line and weight balance information for the aircraft?
The POH.
When manually calculating CG, _______
weight, moment, and arm are used.
Moment:
the product of the weight of an item multiplied by its arm. Moments are expressed in pound-inches (in-lb). Total moment is the weight of the airplane multiplied by the distance between the datum and the CG.
Arm:
the distance from the datum to the CG of any component part or any object loaded on the aircraft. When the object or component is located aft of the datum, it is measured in positive inches; if located forward of the datum, it is measured as negative inches or minus inches.
How to manually calculate the CG and the gross weight:
Ascertain from the pilot’s operating handbook the empty weight of the aircraft and determine the weights of people, baggage, and fuel. Multiply each weight by the arm to find the moment. Add all the weights to get the gross weight. Divide the total moment by the total weight of the aircraft to determine the CG in inches from the datum. This is typically done by filling in a chart.
Each aircraft is given an envelope or a CG range by the manufacturer _______
in the form of a chart in the POH. The aircraft will be safe to fly as long as the CG calculations fall within the envelope window or range.
