Project-1: Powertrain for aircraft in runways
Q1) Power train for aircraft in run ways
part A:
1) Search and list out the total weight of various types of aircrafts.
A) Aircrafts can be classified in to two types :
a) Aero stat ( lighter than air ) : Any aircraft can be kept aloft by a gas which is lighter than airfalls under this category.
b) Aerodyne ( heavier than air ): Aero dyne is the technical name for any type of craft heavier than the air . This covers all the aircraft that derives flight in prinicipally with the aerodynamic forces.
These two are further classified in to sub catagories which are captured as below : 
This is an Overview of the different types of aircraft. the list is not exhaustive, as the aircraft still can be classified in to many categories based on the types of engines (type, number), number of wings, mach number, range, payload, source of power and the list goes on.
here are the some aircrafts
MTOW : maximum take off weight , MLW = Maximum Landing weight , TOR = Take off Run
2) Is there any difference between ground speed and air speed?
A) Yes there is difference between the ground and the air speed
With reference to the above image, I'm going to differentiate the ground speed and the airspeed.
Ground speed is the aircraft speed relative to the ground that it explains how speed can aircraft travel in the ground. It is not dependent on the airspeed.
Here Airspeed is the relative motion between the object and the air. This is also an important parameter for aerodynamic lift generation. This air speed of the object cannot be measured directly from the ground, it depends upon the ground and the wind speed, in fact it is the "vector difference" between the ground and wind speed. (As shown in the above figure).
On a perfectly still day, the airspeed is equal to the ground speed. But if the wind is blowing in the same direction that the aircraft is moving, the airspeed will be less than the ground speed.
3. Why is it not recommended to use aircraft engine power to move it on the ground at the Airport?
A) "Taxiing" refers to the aircraft movement while on the ground under its own power. This term excludes the accelerating run before take-off and the decelerating run after landing.
The jet engine used is generally not preferred as the primary thrust for taxiing because a large amount of fuel is wasted while the aircraft is still on the ground which could have been used for flying. Since the cost of fuel is one of the biggest expenses in the airline business, many companies are planning to switch to electric taxiing to save fuel and reduce emissions.
There are 2 more important reasons,
i) If the high mounted engines are powered there is a huge risk of the jet blast which may affect the surrounding building and the environment.
ii) In case of low mounted engines are turned on there is a higher possibility of any gravel or other impurities lying in the ground may enter the engine and damage it.
Here is where Pushback trucks &Electric taxiing systems use electric motors fitted inside the wheels of the aircraft’s landing gear. Electric power is supplied to these motors by an on-board Auxiliary Power Unit (APU). This innovative new approach enables airplanes to move backward and forward solely under electric power. This way, aircraft can avoid reliance on main engines for traversing the airport taxiways while burning fuel unnecessarily.
4) How an aircraft is pushed to runway when its ready to take off?
A) As explained in the previous answer, "Taxiing" refers to the aircraft movement while on the ground under its own power. This term excludes the accelerating run before take-off and the decelerating run after landing.
So we know the repercussions that might occur when the engine is used on the runway. So Pushback seemed to be a widely popular option for rolling the aircraft on the runway
Pushback means the movement of an aircraft from nose-in parking stand using the power of a specialized ground vehicle attached to or supporting the nose landing gear. Conventionally a tow bar is a link used between the aircraft and Pushback tug.
Since the pilots have limited vision from the cockpit what lies behind & side of the aircraft, most of the steering will be done by the driver in Pushback.
5. Learn about take off power, tyre design, rolling resistance, tyre pressure, brake forces when landing.
A) Take-off power: It is the phase where the flight leaves the ground and becomes airborne.
Take off performance can be predicted using a simple measure of the acceleration of the aircraft along the runway based on force equilibrium.
The forces involved will be,
T – Thrust of propulsion system pushing aircraft along runway.
D – Aerodynamic Drag of vehicle resisting the aircraft motion.
F – Rolling resistance friction due to the contact of wheels or skids on the ground.
During take-off run the imbalance in these forces will produce an acceleration along the runway where dV/dt is the acceleration along the runway and m is the mass of the vehicle.
Rolling resistance:
The friction between aircraft and runway will be proportional to the normal force exerted by the aircraft on the runway.
F=μ(W−L)
The normal force will be the difference between Weight of aircraft and Lift, the friction coefficient will be typically of a magnitude of 0.02 for a standard tarmac runway.
Tyre Design:
When it comes to safety, tyres are one of the most important components of aircraft. They help to absorb the shock of landing and provide cushioning. It also provides the necessary traction for braking and stopping of an aircraft.An aircraft tyre is designed to withstand extremely heavy loads while landing, take off,taxing, and parking. The number of wheels required for aircraft increases with the weight of the aircraft, as the weight of the aeroplane needs to be distributed more evenly.
Carcass plies are used to form the tire. They are sometimes called casing plies. An aircraft tyre is constructed for the purpose it serves.
1. They support the weight of an aircraft while it is on the ground.
2. It also provides the necessary traction for braking and stopping of an aeroplane.
3. Tyre also helps to absorb the shock of landing and provide cushioning the roughness of takeoff, roll-out, and taxi operations
Unlike an automobile or truck tyre, it does not have to carry a load for a long period of continuous operation. However, an aircraft tyre absorbs the high impact loads of landing, and also it’s operating at high speeds for a short time when required.
Bead : The tire bead is an important part of an aircraft tire. It anchors the tire carcass and provides a dimensioned, firm mounting surface for the tire on the wheel rim. Tire beads are strong. They are typically made from high-strength carbon steel wire bundles encased in rubber. One, two, or three bead bundles may be found on each side of the tire depending on its size and the load it is designed to handle. Radial tires have a single bead bundle on each side of the tire. The bead transfers the impact loads and deflection forces to the wheel rim.
Carcass Plies :Carcass plies, or casing plies as they are sometimes called, are used to form the tire. Each ply consists of fabric, usually nylon, sandwiched between two layers of rubber. The plies are applied in layers to give the tire strength and form the carcass body of the tire. The ends of each ply are anchored by wrapping them around the bead on both sides of the tire to form the ply turn ups. As mentioned, the angle of the fiber in the ply is manipulated to create a bias tire or radial tire as desired.
Tread :The tread is the crown area of the tire designed to come in contact with the ground. It is a rubber compound formulated to resist wear, abrasion, cutting, and cracking. It also is made to resist heat build-up. Most modern aircraft tire tread is formed with circumferential grooves that create tire ribs. The grooves provide cooling and help channel water from under the tire in wet conditions to increase adhesion to the ground surface.
Sidewall :The sidewall of an aircraft tire is a layer of rubber designed to protect the carcass plies. It may contain compounds designed to resist the negative effects of ozone on the tire. It also is the area where information about the tire is contained. The tire sidewall imparts little strength to the cord body. Its main function is protection.
Tire Pressure: The pressure usually operates at higher pressure up to 200 psi for domestic and as well international flights which are usually heavier.
Brake forces when landing:
There are three kinds of braking forces that can be employed in the aircraft to decelerate it in the run way.
1. Engine power: The most important action to achieve deceleration from a speed at which the engines are still producing forward motion is to select all thrust/power levers to the ground idle position promptly, and if available, continue the action through to the selection of reverse thrust or reverse propeller pitch. Thrust reversers and reverse propeller pitch are most effective at high speeds.
2. Wheel brakes: To be effective, braking action at any speed depends upon sufficient friction existing between the tires and the runway surface achieved through freely rotating wheels.
3. Mechanical spoilers:The mechanical deflection of parts of the wing upper surfaces and tail cone assembly can assist deceleration in two ways:
- Directly, by increasing aerodynamic drag on the moving aircraft. This can be achieved by raising upper wing surface panels called ground spoilers or by operation of a tail cone ‘clamshell’ type air brake.
- Indirectly by increasing the effective downward load on the landing gear and thereby increasing the efficiency of wheel braking.
6 a). With necessary assumptions, calculate the force and power required to push / pull an aircraft by a towing vehicle.
A) Here the pushback trucks experience two kinds of forces acting on them when they try to push/pull the aircraft.
i) Rolling resistance force
ii) Aerodynamic drag force
iii) Hill climbing force
Push/Pull Power Calculation of Towing Vehicle:
Let's assume,
Towing Vehicle mass = 50000 kg,
Aircraft mass = 183700 kg
Total mass of the vehicle = (50000+183700)= 233700 kg
Speed of the vehicle (V)= 10 km/hr = 2.77 m/s
Rolling Resistance Force
Frr = `mu` * m * g
= 0.013*23370 *9.8
=29773.38N
Aerodynamic Drag Force
Fad = ( 1/2)* `rho` *v^2*A *(Cdt + Cda)
=(1/2) * 1.225 *(2.778)^2 *20*(0.5+0.045)
= 51.52N
Hill Climbing Force
Fhc = m* g*sin`phi`
= 23370 * 9.8 * sin0
= 0N
Total Traction Force Fte = Frr+ Fad + Fhc
= 29773.38 +51.52+0
= 29824.9N
Total Power = Fte * V/1000
= 29824.9 *2.77 /1000
= 82.82KW
B) Develop the model for the calculated force and power using Simulink.
Main model :
Aero dynamic Force :
Rolling resistance Force :
Hill Climbing Force :
7. A. Design an electric powertrain with type of motor, it’s power rating, and energy requirement to fulfill aircraft towing application in Simulink. Estimate the duty cycle range to control the aircraft speed from zero to highest. Make all required assumptions. Prepare a table of assumed parameters. Draw a block diagram of powertrain.
(Hint :DC7 Block)
Assumptions for Powertrain Design
Aircraft Mass = 183700 Kg
Towing Vehicle Mass = 50000 Kg
Rolling Resistance Co-efficient = 0.013
Air Density = 1.225 Kg/m^3
Towing Vehicle Drag Co-efficient = 0.5
Aircraft Drag Co-efficient = 0.045
Frontal Area = 20 m^2
Inclination Angle = 0 rad
Tyre Pressure = 203 PSI/14 bar
Towing Velocity(V) 10 Km/hr = 2.778 m/s
Towing Time(t) = 2 min
Radius of the Towing Vehicle Wheel = 0.38 m
Therefore from the above modal, we have calculator the Traction Force = 29824.8927 N
Power = Force * Velocity
= 29824.8927 *2.778
= 82.84Kw
As we know Torque(T) = Force(F)* Wheel Radious(r)
= 29824.9025 * 0.38
= 11333.45N − m
Required Energy(E) for towing application based on the assumed time, that is E = P*t
= 82.84 * (120/3600)
= 2.760kwh
For this application an induction motor or a BLDC can be used with a proper gear system
The Motor output power is the input power of the towing vehicle so to obtain maximum speed, the duty cycle needed is calculated as below.
DutyCycle = Output Power/Input Power
= 82.84/90 *100
=92 %
The duty cycle range to control the aircraft speed from zero to highest is from 0 to 92%
Main model :
Results:
Block diagram for power train of Towing Vehicle :
Electric Vehicles, consist of a battery, connected to an electric motor(eitherAC or DC) via an inverter and a motor controller. As automotive batteries generally operate on DC current, while the gird operates AC, a converter is needed to transfer power to the battery. One of the key advantages of an EV is its much higher levels of energy efficiency.
B) Also, Design the parameters in excel sheet.
