Project-1: Powertrain for aircraft in runways

Search and list out the total weight of various types of aircrafts.

From total weight in the question it is assumed that Operating Empty Weight is being asked

Here are listed some of the most famous commercial aircrafts along with their variant and OEW

Is there any difference between ground speed and air speed? 

Types of Airspeeds

1-Groundspeed

2-True Airspeed

3-Indicated Airpeed

Groundspeed is the speed of the aircraft over the ground i.e. no air mass or atmospheric conditions effect it.

True Airspeed is basically groundspeed plus headwind minus tailwind. It is equal to groundspeed in the still air.

True Airspeed = Groundspeed + Headwind - Tailwind

Indicated Airspeed is measured by the pitot tube that caliberates the true airspeed. for the air density involved. Basically Indicated Airspeed and True Airspeed may both be equal at the ground or take off level but as the height of the aircraft increases Indicated Airspeed gets less than the True Airspeed as the density of air gets lower at high altitudes.

Why is it not recommended to use aircraft engine power to move it on the ground at Airport? 

It is not recommended due to the the possiblility of the jet blast damage.

A must watch to get the concept right

https://www.youtube.com/watch?time_continue=128&v=B0Pnvgc2_gA&feature=emb_logo

How an aircraft is pushed to runway when its ready to take off?  

Aircrafts are usually pushed to runway for take off purposes using push back trucks. afterwards these aircrft use their own engine to taxi and get ready for the take off.

Learn about take off power, tyre design, rolling resistance, tyre pressure, brake forces when landing. 

Take-off Power:

The take off power is the power generated by the engines for the aircraft to take off.

It is not the maximum power that engines could produce , because extending engines to such limits could reduce their longterm useability. Therefore, pilots use longer take offs instead of full engine throttle for take off.

Tire Design:

Airplane tires are very strong as they use cords of nylon, or a synthetic polymer called aramid, that are embedded below the tread.The simple tread pattern, designed primarily to prevent hydroplaning, and the reinforcing cords embedded beneath allow commercial airplane tires to touch down at high speeds and drag along the tarmac, which is why you see smoke, before the rotation of the wheels catches up to the velocity of the plane.

Source: https://www.popularmechanics.com/flight/a22479/why-airplane-tires-never-have-a-blowout/

Rolling Resistance:

it is the resistance of the tire to motion. Aircrafts experince it only at take off , landind and taxing.

Tire Pressure:

These tires are inflated upto 6 times that of the tire pressure of normal passenger car.i.e 200 psi. and are filled with nitrogen instead of oxygen as the the latter reacts with the tire material at high temperatures and weakens them.

brake forces when landing:

All commercial aircrafts use ABS (Anti locking Braking System). Most of the Air lines use hydraulics for braking but Boeing 787 Dreamliner uses electric power to push the carbon brakes thus saving a lot of fuel by cutting the weight associated with hydraulics architecture.

With necessary assumptions, calculate the force and power required to push / pull an aircraft by a towing vehicle. 

Basically the tires of an aircraft are inflated to such high pressures that the co-efficient of the rolling resistance is very very low.

For this Problem we are assuming the co-efficeint of rolling resistance of "0.006" for the Airbus A380 whose maximum ramp weight is 562,000 kg.

Force to move the aircraft from standstill=

Co-efficient of rolling resistance* Mass of Aircraft* Acceleration due to gravity

= 0.006*562000*9.8= 33,045 N

To pushback this aircraft at a nominal speed of 15mph(8.9 m/s), the pushback truck would require a power = 8.9 m/s * 33,045 N = 290796 W = 291 KW

Design an electric powertrain with type of motor, it’s power rating, and energy requirement to fulfill aircraft                   towing application. 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. 

The motor that would be best for the use would be Switched Reluctance Motor(SRM) because they have the highest speed ratio,x (x>6). Due to this these motors could provide very high starting torque compared to the induction(x=4) or permanent magnet motors(x<2)

where x= ratio of the maximum speed to the base speed.

The power rating of the motor should be equal to 300 kW (291 kW + air drag power requirement).

291 kW has been derived in the previous question.

Average time for the push back truck to take the plane to runway = 15.9 min = 954 s

Source: https://www.planestats.com/aptot_2016mar

So the energy required = 954 seconds * 300 kW = 286 MJ

For the A380 pushback operation the duty cycle would be close to "1" as the motor is designed accordingly.

but for the smaller Air crafts like Airbus A350 (Maximum Ramp Wieght 249 tonnes)

Duty Cycle = Pout / Pin = Mass of A350 / Mass of A380 = 249 / 562 = 0.4430 or 44.30 %