Asshray's AIR-001 course work. Lv 1

Asshray's Aviation Report, Part 1

23 / 12 / 2024

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History of Aviation

Objective:

Explore the theory of aviation and different types of planes. Gain a brief understanding of the history of aviation and the pioneers of the field.

Learning:

Aviation has a history of more than 2000+ years, and it goes like...

References:

1. Click here: History of aviation

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Task 3 - Design an Airfoil in Fusion 360

Objective:

1. Design an airfoil with NACA 4412 coordinates in Fusion 360. Use the DAT to spline converter or canvas tool to sketch the airfoil.
2. Understand terms such as angle of attack, camber line, chord line, and leading edge.
3. Design two versions: one using a wood environment and another using composites. The wing should generate at least 5 newtons of lift at a wind speed of 25 m/s.

Learning:

Basic science behind flight:

With respect to Bernoulli's explanation for any fluid the,

By Bernoulli's Principle, we know that

Also, Angle of attack ∝ Lift {up to a certain value of AOA} If the AOA increases above a certain threshold i.e. above the Critical Angle of Attack then the lift starts to decrease and causes stall.

Basic Definitions:

• Airfoil - Any surface, such as a wing, that provides aerodynamic force when it interacts with a moving stream of air.
• Leading Edge - Front tip of the airfoil.
• Trailing Edge - End tip of the airflow.
• Cord Line - Imaginary straight line that connects the leading & trailing edge.
• Camber - Curvature of the airfoil, where the upper camber means the upper curvature & the lower camber means the lower curvature.
• Mean Camber - Curved line that is midway between the upper and the lower surface, it is the average of upper and lower camber.
• Relative Airflow - Airflow with respect to the wings, basically air which hits the nose of the aircraft & opposes the aircraft motion.
• Angle of Attack (AOA) - Angle between chord line and the relative airflow.
• Angle of Incidence (AOI) - Angle between chord line & horizontal axis (x-axis).
• Wing Span - Distance from wing tip to wing tip.
• Planform - Shape of the wing from above (top view).
• Stagnation Point: Where fluid velocity is ZERO.
• Aspect Ratio - Wing Span : Wing Chord {Gliders have high aspect ratio (less drag high aerodynamic efficiency) & Fighter jets have low aspect ratio (better maneuverability at the cost of increased drag)}

4 Aerodynamic Forces:

1. Lift: It is a +ve upward force generated by the pressure difference between the airfoils. On the top surface, the pressure is large & -ve. This therefore creates a suction force and contributes most to the lift.
2. Thrust: It is a +ve horizontal force generated by the engine when they push air backwards (Newton's 3rd Law).
3. Drag: It is a -ve horizontal force generated by the relative airflow, it is present whenever the aircraft is in motion, it slows down the aircraft.
4. Weight: It is a -ve vertical force created by gravity.
5. Horizontal Eq. if Thrust = Drag & Vertical Eq. if Lift = Weight. Net Eq. if all the 4 forces cancel out.

Types of Airfoil:

1. Symmetric Airfoil: a. The upper & lower camber of the airfoil are symmetrical, here the chord line & the camber line coincide with each other. b. Used in aerobic planes as they easily allow planes to fly upside down. c. Here lift is created by lifting the nose of the aircraft to create an AOA, when the AOA is 0 even the lift generated is 0. Example: Bullet
2. Non Symmetric Airfoil (Cambered Airfoil): The upper & lower camber of the airfoil are un-symmetrical. a. If camber line above the chord line, lift generated is upwards. b. If camber line below the chord line, lift generated is downwards.

Primary Flight Controls (3-Axis):

Note: Ailerons are small hinged plates present at the trailing edge. Spoilers are small hinged plates present between leading and trailing edge.

Airfoil:

The naming of an Airfoil is done with the help of National Advisory Committee for Aeronautics (NACA) nomenclature. Where there can be 4,5 or 6 digits, For 4 digits, NACA ABCD

• 1st Digit (A) gives the maximum camber as %(A)xc
• 2nd Digit (B) gives the position of maximum camber from the leading edge as %(Bx10)xc
• 3rd & 4th Digit (C,D) gives the thickness of the airfoil as %(CD)xc -> c, is the Chord length of the airfoil. Example: NACA 4312. (Assume chord length(c) = 200mm) Maximum Camber= 4% of 200, i.e. 0.04x200= 8mm Pos. of max camber= 30% of 200, i.e. 0.30x200=60mm Thickness of airfoil= 12% of 200, i.e. 0.12x200=24mm

For 5 digits, NACA ABCDE

• 1st Digit (A) gives the coefficient of lift (CL) as {(A)x(3/2)}/10
• 2nd & 3rd digit (BC) gives the position of maximum camber from leading edge as M% of c, where M=(BC)x(1/2)
• 4th & 5th Digit gives the thickness of the airfoil as %(DE)xc -> c, is the Chord length of the airfoil. Example: NACA 46015. (Assume chord length(c) = 200mm) Coefficient of lift= {4x(3/2)}/10, i.e. 6/10 = 0.6 Pos. of max camber= 60x(1/2)=30, i.e. 30% of 200 from leading edge, 0.30x200=60mm Thickness of airfoil= 15% of 200, i.e. 0.15x200=30mm

NACA 4412 Airfoils made in Autodesk Fusion 360

Span= 162.5 mm Chord Length= 100 mm Note: The above airfoil is made using carbon fiber material.

NACA 4412 Airfoils simulation in Autodesk CFD:

Therefore, @ 15° AOA, wind speed 25m/s, chord length 100 mm & airfoil span 162.5 mm Lift= 8.24 N Drag= 2.45 N Click here to view the simulation report generated by Autodesk CFD.

References:

1. Click here: Basics of flight
2. Click here: Airfoil Definitions playlist
3. Click here: NACA Nomenclature
4. Click here: Turbulence

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Task 2 - Mission Possible

Objective:

Connect the mission planner, FC & put a geofence around UVCE so that the UAV doesn't go outside and plan a small autonomous flight.

References:

1. Click here:How to setup Mission Planner
2. Click here: How to use Mission Planner: Geofencing, Surveying & Automation
3. Click here: How to read the nos on the motor

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Task 4 - Assembling a Drone Using Ecalc

Objective:

1. Write about different materials to assemble a drone with an empty weight of 800g.
2. State the reasons behind material selection and endurance. Calculate the weight and the thrust-to-weight ratio needed, battery, ESC, and other materials needed for the drone.
3. Read data sheets of motors.

Pre-requisites I learned:

1. How to read the nos on a motor:

2. Reading nos on a propeller:

Propeller Specs reading: 
There are 2 main factors in the propeller i.e. Diameter & Pitch. Diameter is the measure (in inches) of the propeller from one end to the other  & Pitch is the distance (in inches) travelled by the propeller  in one revolution. It's denoted by 4 digits,
***Note:***
Example: if the numbering on the prop is ABCD R, {ABCD are nos}
AB-> Prop's diameter is AB inches
CD-> Prop's pitch is C.D inches
R-> Clockwise prop
If it has R at the end its a clockwise prop, if there is nothing then anticlockwise propeller.
Example: 1045 indicates 10" diameter, 4.5" pitch and its anticlockwise.

Major Learning:

The following would be the materials needed to assemble a drone;

1. Chassis: If cost is not a concerning factor then Carbon Fiber would be the best chassis as it has best strength-to-weight ratio with high endurance. But if cost is a major concern then plastic or fiberglass would be the best choice for making a chassis.
2. Motors: Thumb rule while selecting the motors should be that the net thrust generated by all the motors should be at least 2x the weight of the drone. For racing drones etc., the thrust to weight ratio is about 8:1 (net thrust generated by the motor is 8x the weight of the drone), for Payload drones it is around 4:1 & for Normal drones it is 2.5:1.
3. Propeller: No. of blades ∝ Drag ∝ Overall power req. ∝ (1/Efficiency) {2 blade propellers are the most stable}

Parameter	** Threshold**	RPM	Thrust	Use Case
High Diameter	> 8 inches	Low	High	Normal drones, heavy payload, stable
Low Diameter	< 8 inches	High	Low	High speed race drones
High Pitch	> 4.5 inches	Low	Medium	Moving Forward (Pitch motion)
Lower Pitch	< 4.5 inches	High	High	Stable Hovering

• High Diameter: Moves more air because of greater surface area, providing greater lift but spins slower.
• Low Diameter: Spins faster, but produces less lift, because of less surface area.
• High Pitch: Designed for speed, with a focus on forward movement.
• Low Pitch: Best for hovering and stability, generating more lift at lower speeds. To summarize:
• Low Diameter & High Pitch = Speed and Agility {Hard to control}
• High Diameter & Low Pitch = Stability and Hovering {Easy to control}

1. Electronic Speed Controller (ESC): An electronic circuit connected to the motor of the drone and the FC, which:
   • Controls the speed and direction of the motor.
   • Prevents the motor from excess flow of current.
   • Converts control signals (from the FC) into electrical pulses to run the motors. ESC selection: The selected ESC should have 20% more amp reading than the motor. {Amp reading is the amount of current drawn by the motor at 100% throttle}
2. Battery: We use Li-Po batteries in drone because of their low weight & high discharge rate. C Rating/Discharge rating is how quickly the current can be discharged from the battery, basically supplying burst shot of current which usually lasts for a very less time, they are useful when giving throttle, when the throttle is given the discharging rate should be as high as possible. Ex: If a battery of 3000 mAh is rated at 30C, then 30 times the capacity of battery, is the amount of burst of current it can supply without damaging the battery/drone, i.e. in this case it is 30x3000 mA= 90 A Battery selection: The selected battery should have high capacity and high C rating, with minimal weight as required by the motor.

Ecalc:

Empty weight: 800g

Components	Spec
Battery	Tattu 14.8V 4S Lipo Battery Pack; 22000 mAh & 25-35 C
ESC	40 A
Motor	T Motor MN2212 V2.0 KV920
Propeller	10" x 3.3" Carbon Fiber Anti Clockwise Propeller Pair

References:

1. Click here Datasheet of the above specified motor.
2. Click here: How to read the nos on the motor
3. Click here: Propeller
4. Click here: ESC
5. Click here: Battery

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To continue reading my report click here