Project-1: Powertrain for aircraft in runways

AIM(1):-Search and list out the total weight of various types of aircrafts.

• Aircraft Gross Weight:-

• AS per federal aviation department, aircraft gross weight is defined as the total weight at any moment during flight or ground operation.
• The aircraft gross weight decreases during flight due and oil consumption.In some case gross weight may vary due to drop in payload or inflight refueling.where as on the other hand when the brakes are released the gross weight will be equal to take off weight.
• During flight an aircraft gross weight will be referred as infight weight.

• Types of aircraft weights are the following:

• Manufactures empty weight:-

• It includes the weight of aircraft of the entire flight with its integral working parts, but excludes Baggage, passenger and fuels.

• Zero fuel weight:-

• It includes total weight of aeroplanes including unusable fuels but excludes total weight of useable fuel at board.

• Payload:

• It is load carrying capacity of an aircraft which includes passenger, cargo and fuels, But if it is in the case of cargo flight it determines the total load of logistics weight of the container which it needs to transport.

• Maximum take off weight:-

• This is the maximum weight at which the aircraft would be made to takeoff.

• Regulated take off weight:-

• Depending on different factors (flap setting, altitude, length of runway),RTOW varies for each take off.but can never be high for MTOW.

• Maximum landing weight:-

• It is maximum weight at which an aircraft is permitted to land.

• Maximum Ramp weight:-

• It is the maximum weight used for towing aircraft on the ground.

• Listed below are the types of aircraft with its weight:-

AIM(2):-Is there any difference between ground speed and air speed?

• Ground Speed:-

• Speed of aircraft relative to the surface of earth is known as Ground speed. It is the horizontal speed of an aircraft.It is the vector sum of true aircraft's true air speed, wind speed and wind direction.

• Air Speed:-

• Air speed is the speed relative to the air it is flying in. Airspeed indicator indicates speed of aircraft's relative to air mass.It is the vector difference between ground and wind speed.
• As shown in below gifs, the relation of Ground and air speed relative to wind.

AIM(3):-Why is it not recommended to use aircraft engine power to move it on the ground at Airport?

• An aircraft can use its own power to move on the ground but due to few reasons it is not recommended.

1. High amount of thrust produced may damage terminal building or near by equipments.
2. Possibility of sand and debris getting sucked into the engine.
3. If the wheels of aircraft lose control then it may also result into the accident.
4. Cost of fuel is very high.

• Thus taxiing or pushback is the method of driving aircraft on the ground.

AIM(4):-How an aircraft is pushed to runway when its ready to take off?

• Pushback tugs are used to move the aircraft and it will park the aircraft closer to its departure way.
• These pushback tugs are used at front wheel of an aircraft which also helps to move aircraft in reverse direction.
• Below is shown image of pushback tractor,

• Once aircraft is on its way, pilot starts the engine one by one to advance the thrust level one by one.
• When aircraft starts moving overcoming wheel friction it won`t need much thurst.

AIM(5):- Learn about take off power, tyre design, rolling resistance, tyre pressure, brake forces when landing.

• Take Off Power:- It is the power required to fly an aircraft from the ground. There are 4 types of forces which are considered while taking off any aircraft those are Thrust, Drag, Weight and Lift. Take off Power= Total force*velocity

1. Thrust:- This is the force which helps the aircraft to move in the direction of motion which is created by propeller. Air is pulled in and then oushed out in opposite direction.
2. Weight:- It is the force caused by gravity which is F_weight = m*g.
3. Lift:- It is the force which helps an airplane to hold in the air. The wings of aircraft creates most of this force.
4. Drag: It is the force acting in opposite to the direction of motion. This force is caused by friction and differences in air pressure.

• The net Thrust of an jet engine is:

`F=m(v_j-v)`

• Where,

`m`= Mass of air passing through the engine

`v_j`=I's speed at the nozzel

`v`=The airplane's speed

• The Drag Equation,

`D=1/2*rho*C_d*A*v^2`

• where,

`rho`= Density,

`C_d`= Drag Co-efficient

`A` = Area

`v`= Velocity

• Rolling resistance:-It is the frictional force created betwween wheels and runway.

• Tyre design:-

• From design point of view Tires are classified according to their dimensions, configuration ( tubed or tubeless )and strength (ply rating). For different applications of aircraft suitable tires are designed and used for better safety and smooth control.
• Ply rating provides the strength number to the tyre. Earlier number of plies used in tyres are proportional to the strength of tyre.
• Tubed tyres are not much used.Nowadays mostly all aircrafts are using tubeless tyres which prevents air leak and less susceptible to tyre creep.

• Tyre Pressure:-

• Aircraft tyres operate at such high pressure, speed, load and different temperature so it is must to take care of tyres regularly as it serves critical while landing or take off.
• Pressure maitained in the tyre is the foremost thing to check which can avoid to happen any accident.
• To make sure to get most value and contribute to the safe operation of aircraft following actions should be taken:

1. Perform daily pressure checks with a calibrated gauge.
2. Target the highest pressure recommended in the AMM (aircraft maintenance manual)or POH(pilot's operating handbook)at 105 percent of operating pressure.
3. Compensate for ambient temperature changes.

• Braking force:

• To stop a huge and heavy aircraft landing with almost a 160-180mph speed it requires a lot of braking force.Aim of braking is to minimise the distance keeping safety in mind.
• Electric or hydraulic brakes are used to stop the aircraft.Hydraulic brakes put on weight of the aircraft.
• Vtd: It is touch down velocity, the velocity of an aircraft having it with which it has landed on ground it should be staling speed of aircraft.
• To acheive stall speed drag and decceleration of aircraft is increased which is obtained by braking and reverse thrust.

`(dv)/(dt)=(-T-D-F)/m`

• Brake force= Mass*decceleration
• T = Thrust of propulsion
• D = Aerodynamic drag force of aircraft
• F = Rolling resistance friction due to contact of wheels on the ground
• m = Mass

• Below is shown image of an aircraft landing,

AIM(6)(A):- With necessary assumptions, calculate the force and power required to push / pull an aircraft by a towing vehicle.

• The force required to move an aircraft on absolute flat surface with no wind and at constant speed is equals to rolling resistance of aircraft and towing vehicle and also the drag force which will be acting in oppsite direction of motion.
• The rolling resistance for the aircraft and towing vehicle can be calculated as,

`F_(rr1)= C_(rr)*m_1*g`

`F_(rr2)= C_(rr)*m_2*g`

• Where,

`C_(rr)`= Rolling Resistance Co-efficient

`m_1`= Mass of Aircraft(KG)

`m_2`= Mass of towing Vehicle(KG)

`g`= Gravity(m/s2)

• Thus,

Total `F_(rr)=F_(r1)+F_(r2)`

`=C_(rr)*(m_1+m_2)*g`

• Drag force acting on the tow will be,

`F_d=1/2*C_d*rho*A*v^2`

• Where,

`rho`= Density(kg/m3)

`C_d`= Drag Co-efficient

`A` = Area(m2)

`v`= Velocityof towing vehicle(m/s)

• Assuming the values for all parmters

Crr = 0.018, g= 9.81 m/s2, m1 = 50000 kg, m2 = 22000 Kg, Cd =0.65, A = 100 m2, v= 6.94m/s, p= 1.2kg/m3,

• Pulling force `=F_(rr)+F_(d)`

`=C_(rr)*(m1+m2)*g+1/2*rho*A*C_d*v^2`

`=0.018+(50000+22000)*9.81+0.5*1.2*100*0.65*(6.94)^2`

`=12713.76+1878.38`

• Pulling Force F1 `=14591.14`

`=14.59KN`

• Power Required for towing,

`P_1=F*v`

`=14.59*6.94`

`P_1=101.3KW`

(B)Develop the model for the calculated force and power using Simulink.

AIM(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)

• To calculate duty cycle few more practical assumptions need to be consider,

• Towing tractor tyre radius = 0.5m
• Towing tractor gear ratio = 11
• Operational time for towing = 0.25hr (15 min)

• Torque = Force * (radius/gear ratio)
• Torque = 14.59*(0.5/11) = 663.18 J

• Energy = Power * Time
• Energy = 101.3* 0.25 = 25.325 KWh

• From the above results we have selected motor of rating 110Kw (150 HP) motor of wound type 300V, 1750 RPM,
  considering efficiency = 90%
• Thus, Input power of motor = Output power/ Efficiency
• Input power of motor = 110/0.9 = 122.22 Kw
• Duty cycle = Output power/input power
• Duty cycle = 101.3/122.22
• Duty cycle = 82.88%

Thus range of duty cycle to control aircraft speed is from 0- 82.88%

• Simulink model:

• As shown in above model,we are using dc 7 four quadrant chopper dc drive block.step input is used for give speed input to the block.
• Battery is used for supply input to the dc7.the outputs of the dc 7 block is shown in scope.

• Battery output:-

• Output:-

• BLOCK DIAGRAM:-

(B) Also, Design the parameters in excel sheet.

Here,The spreadsheet File is uploaded.

https://docs.google.com/spreadsheets/d/1N9y_PPhBe7lE-iJF5HXGcoQUJgc-5XBG/edit?usp=sharing&ouid=118283153574063949967&rtpof=true&sd=true