Project-1: Powertrain for aircraft in runways

What is an Aircraft?

An aircraft is a vehicle that is able to fly by gaining support from the air. It counters the force of gravity by using either static lift or by using the dynamic lift of an air foil, or in a few cases the downward thrust from jet engines. Common examples of aircraft include airplanes, helicopters, airships (including blimps), gliders, paramotors and hot air balloons.

Aircraft weight

Manufacturer's empty weight (MEW) also called Manufacturer's Weight Empty (MWE) or Licensed Empty Weight

• It is the weight of the aircraft "as built" and includes the weight of the structure, power plant, furnishings, installations, systems and other equipment that are considered an integral part of an aircraft. This excludes any baggage, passengers, or usable fuel.

Zero-fuel weight (ZFW)

• This is the total weight of the airplane and all its contents (including unusable fuel), but excluding the total weight of the usable fuel on board. As a flight progresses and fuel is consumed, the total weight of the airplane reduces, but the ZFW remains constant.

Operating empty weight (OEW) (Roughly equivalent to basic empty weight on light aircraft)

• It is the basic weight of an aircraft including the crew, all fluids necessary for operation and all operator items and equipment required for flight but excluding usable fuel and the payload.

Payload

• It is the carrying capacity of an aircraft. It includes cargo, people, extra fuel. In the case of a commercial airliner, it may refer only to revenue-generating cargo or paying passengers.

Maximum takeoff weight (MTOW)

• This is the maximum weight at which the pilot of the aircraft is allowed to attempt to take off.

Regulated takeoff weight (RTOW)

• Depending on different factors (e.g. flap setting, altitude, air temperature, length of runway), RTOW or maximum permissible takeoff weight varies for each takeoff. It can never be higher than MTOW.

Maximum Landing weight (MLW)

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

Maximum ramp weight (MRW) also called maximum taxi weight (MTW)

• It is the maximum weight authorized for maneuvering (taxiing or towing) an aircraft on the ground.

Aircraft gross weight

• It is the total aircraft weight at any moment during the flight or ground operation. This decreases during flight due to fuel and oil consumption.

Classification of Aircrafts based on thier weights

This is a list of aircraft sorted by maximum takeoff weight.

MTOW = Maximum take-off weight,

MLW = Maximum landing weight,

TOR = Take-off run (SL, ISA+15°, MTOW),

LR = Landing run (SL, ISA+15°, MLW)

Type	MTOW [kg]	MLW [tons]	TOR [m]	LR [m]	ICAO category	FAA category
Antonov An-225	6,40,000	591.7	3500	-	Heavy	Super
Scaled Composites Model 351 Stratolaunch	5,89,670	-	3660	-	Heavy	Super
Airbus A380-800	5,75,000	394	3100	1930	Heavy	Super
Boeing 747-8F	4,47,700	346.091	3100	1800	Heavy	Heavy
Boeing 747-8	4,43,613	306.175	3100	-	Heavy	Heavy
Boeing 747-400ER	4,12,770	295.742	3090	-	Heavy	Heavy
Antonov An-124-100M	4,05,060	330	2520	900	Heavy	Heavy
Boeing 747-400	3,96,900	295.742	3018	2179	Heavy	Heavy
Lockheed C-5 Galaxy	3,81,000	288.417	2530	1494	Heavy	Heavy
Boeing 747-200	3,77,840	285.7	3338	2109	Heavy	Heavy
Boeing 747-300	3,77,840	260.32	3222	1905	Heavy	Heavy
Airbus A340-500	3,71,950	240	3050	2010	Heavy	Heavy
Airbus A340-600	3,67,400	256	3100	2100	Heavy	Heavy
Boeing 777F	3,47,800	260.816	2830	-	Heavy	Heavy
Boeing 777-300ER	3,51,800	251.29	3100	-	Heavy	Heavy
Boeing 777-200LR	3,47,450	223.168	3000	-	Heavy	Heavy
Boeing 747-100	3,40,200	265.3	-	-	Heavy	Heavy
Airbus A350-1000	3,08,000	233.5	-	-	Heavy	Heavy
Boeing 777-300	2,99,370	237.683	3380	-	Heavy	Heavy
Boeing 777-200ER	2,97,550	213	3380	1550	Heavy	Heavy
Airbus A340-300	2,76,700	190	3000	1926	Heavy	Heavy
McDonnell Douglas MD-11	2,73,300	185	2990	1890	Heavy	Heavy
Airbus A350-900	2,70,000	175	2670	1860	Heavy	Heavy
Ilyushin Il-96M	2,70,000	195.04	3115	2118	Heavy	Heavy
McDonnell Douglas DC-10	2,56,280	183	2990	1890	Heavy	Heavy
Boeing 787-9	2,54,000	192.777	2900	-	Heavy	Heavy
Boeing 787-10	2,54,000	201.849	-	-	Heavy	Heavy
Airbus A340-200	2,53,500	181	2990	-	Heavy	Heavy
Ilyushin IL-96-300	2,50,000	175	2600	1980	Heavy	Heavy
Airbus A330-300	2,42,000	185	2500	1750	Heavy	Heavy
Airbus A330-200	2,42,000	180	2220	1750	Heavy	Heavy
Lockheed L-1011-500	2,31,300	166.92	2636	-	Heavy	Heavy
Boeing 787-8	2,28,000	172.365	3300	1695	Heavy	Heavy
Lockheed L-1011-200	2,11,400	-	-	-	Heavy	Heavy
Ilyushin IL-86	2,08,000	175	-	-	Heavy	Heavy
Boeing 767-400ER	2,04,000	158.758	3414	-	Heavy	Heavy
Airbus A300-600R	1,92,000	140	2385	1555	Heavy	Heavy
Boeing 767-300ER	1,87,000	136.08	2713	1676	Heavy	Heavy
Concorde	1,85,000	111.1	3440	2220	Heavy	Heavy
Airbus A300-600	1,63,000	138	2324	1536	Heavy	Heavy
Boeing 767-300	1,59,000	136.078	2713	1676	Heavy	Heavy
Airbus A310-300	1,57,000	124	2290	1490	Heavy	Heavy
Vickers VC10	1,52,000	151.9	-	-	Heavy	Heavy
Boeing 707-320B	1,51,000	97.5	-	-	Heavy	Heavy
Boeing 707-320C	1,51,000	112.1	-	-	Heavy	Heavy
Douglas DC-8-61	1,47,000	-	-	-	Heavy	Heavy
Airbus A310-200	1,42,000	123	1860	1480	Heavy	Heavy
Airbus A400M	1,41,000	122	980	770	Heavy	Heavy
Douglas DC-8-32	1,40,000	-	-	-	Heavy	Heavy
Douglas DC-8-51	1,25,000	-	-	-	Medium	Large
Boeing 757-300	1,24,000	101.6	2550	1750	Medium	Large
Boeing 707-120B	1,17,000	86.3	-	-	Medium	Large
Boeing 757-200	1,16,000	89.9	2347	1555	Medium	Large
Boeing 720B	1,06,000	79.5	-	-	Medium	Large
Boeing 720	1,04,000	79.5	-	-	Medium	Large
Tupolev Tu-154M	1,04,000	80	-	-	Medium	Large
Tupolev Tu-204SM	1,04,000	87.5	2250	-	Medium	Large
Convair 880	87,500	-	-	-	Medium	Large
Boeing 737-900	85,000	66.36	2500	1704	Medium	Large
Boeing 737-900ER	85,000	71.35	2804	1829	Medium	Large
Boeing 727-200 Advanced	84,000	70.1	-	-	Medium	Large
Airbus A321-100	83,000	77.8	2200	1540	Medium	Large
Boeing 737-800	79,000	65.32	2308	1634	Medium	Large
Boeing 727-200	78,000	68.1	-	-	Medium	Large
McDonnell-Douglas MD-83	73,000	63.28	-	-	Medium	Large
Boeing 727-100	72,500	62.4	-	-	Medium	Large
Boeing 727-100C	72,500	62.4	-	-	Medium	Large
McDonnell-Douglas MD-90-30	71,000	64.41	2165	1520	Medium	Large
de Havilland Comet 4	70,700	-	-	-	Medium	Large
Boeing 737-700	70,000	58.06	1921	1415	Medium	Large
Airbus A320-100	68,000	66	1955	1490	Medium	Large
Boeing 737-400	68,000	54.9	2540	1540	Medium	Large
de Havilland Comet 3	68,000	-	-	-	Medium	Large
Boeing 377	67,000	-	-	-	Medium	Large
Boeing 737-600	66,000	54.66	1796	1340	Medium	Large
Airbus A220-300	65,000	57.61	1890	1494	Medium	Large
Hawker Siddeley Trident 2E	65,000	-	-	-	Medium	Large
Airbus A319	64,000	62.5	1850	1470	Medium	Large
Boeing 737-300	63,000	51.7	1939	1396	Medium	Large
Boeing 737-500	60,000	49.9	1832	1360	Medium	Large
Airbus A220-100	59,000	50.8	1463	1356	Medium	Large
Airbus A318	59,000	57.5	1375	1340	Medium	Large
Boeing 717-200HGW	55,000	47.174	1950	-	Medium	Large
Douglas DC-7	55,000	-	-	-	Medium	Large
de Havilland Comet 2	54,000	-	-	-	Medium	Large
Boeing 717-200BGW	50,000	46.265	1950	-	Medium	Large
de Havilland Comet 1	50,000	-	-	-	Medium	Large
Douglas DC-6A	48,600	-	-	-	Medium	Large
Douglas DC-6B	48,500	-	-	-	Medium	Large
Embraer 190	48,000	43	2056	1323	Medium	Large
Caravelle III	46,000	-	-	-	Medium	Large
Fokker 100	46,000	39.95	1621	1350	Medium	Large
Douglas DC-6	44,000	-	-	-	Medium	Large
Avro RJ-85	42,000	36.74	-	-	Medium	Large
Handley Page Hermes	39,000	-	-	-	Medium	Large
Embraer 175	37,500	32.8	2244	1304	Medium	Large
Bombardier CRJ900	36,500	33.345	1778	1596	Medium	Large
Embraer 170	36,000	32.8	1644	1274	Medium	Large
Bombardier CRJ700	33,000	30.39	1564	1478	Medium	Large
Douglas DC-4	33,000	-	-	-	Medium	Large
Vickers Viscount 800	30,400	-	-	-	Medium	Large
Bombardier Q400	28,000	28.01	1219	1295	Medium	Large
Bombardier CRJ200	23,000	21.319	1918	1479	Medium	Large
ATR 72-600	22,800	22.35	1333	914	Medium	Large
Saab 2000	22,800	21.5	1300	-	Medium	Large
Embraer ERJ 145	22,000	19.3	2270	1380	Medium	Large
ATR 42-500	18,600	18.3	1165	1126	Medium	Small
Saab 340	13,150	12.93	1300	1030	Medium	Small
Embraer 120 Brasilia	11,500	11.25	1560	1380	Medium	Small
BAe Jetstream 41	10,890	10.57	1493	826	Medium	Small
Learjet 75	9,752	8.709	1353	811	Medium	Small
Pilatus PC-24	8,300	7.665	893	724	Medium	Small
Embraer Phenom 300	8,150	7.65	956	677	Medium	Small
Beechcraft 1900D	7,765	7.605	1036	853	Medium	Small
Cessna Citation CJ4	7,761	7.103	1039	896	Medium	Small
de Havilland Hercules	7,000	-	-	-	Medium	Small
Embraer Phenom 100	4,800	4.43	975	741	Light	Small

2) Difference between ground speed and air speed

Wind Speed

For a reference point picked on the ground, the air moves relative to the reference point at the wind speed.

Notice that the wind speed is a vector quantity and has both a magnitude and a direction. Direction is important.

A 20 mph wind from the west is different from a 20 mph wind from the east.

The wind has components in all three primary directions (north-south, east-west, and up-down).

A positive velocity is defined to be in the direction of the aircraft's motion.

We are neglecting cross winds, which occur perpendicular to the flight path but parallel to the ground, and updrafts and downdrafts, which occur perpendicular to the ground.

Ground Speed

For a reference point picked on the ground, the aircraft moves relative to the reference point at the ground speed.

Ground speed is also a vector quantity so a comparison of the ground speed to the wind speed must be done according to rules for vector comparisons

Airspeed

The important quantity in the generation of lift is the relative velocity between the object and the air, which is called the airspeed.

Airspeed cannot be directly measured from a ground position, but must be computed from the ground speed and the wind speed.

Airspeed is the vector difference between the ground speed and the wind speed.

Airspeed = Ground Speed - Wind Speed

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) Reason for not using airplanes engines for airplane movement on the ground at Airport

Pushback using the jet-engine's thrust-reverser is a highly fuel-consuming and noisy process and also potentially hazardous for personnel working near the plane.

Although many aircraft are capable of moving themselves backwards on the ground using reverse thrust (a procedure referred to as a power back), the resulting jet blast or prop wash light cause damage to the terminal building or equipment.

Engines close to the ground may also blow sand and debris forward and then suck them into the engine, causing damage to the engine. A pushback is therefore the preferred method to move the aircraft away from the gate.

Once the plane is tugged away to a safe distance from the terminal, the plane begins using its own engine power for the rest of the taxing process.

5) Airplane Take OFF

Takeoff is the phase of flight in which an aeroplane leaves the ground and becomes airborne. This usually involves starting with a transition from moving along the ground on a runway.

For light aircraft, usually full power is used during takeoff.

Large transport category (airliner) aircraft may use a reduced power for takeoff, where less than full power is applied in order to prolong engine life, reduce maintenance costs and reduce noise emissions.

In some emergency cases, the power used can then be increased to increase the aircraft's performance.

The aircraft is permitted to accelerate to rotation speed (often referred to as Vr).

The nose is raised to a nominal 5°–15° nose up pitch attitude to increase lift from the wings and effect liftoff.

The speeds needed for takeoff are relative to the motion of the air (indicated airspeed). A headwind will reduce the ground speed needed for takeoff, as there is a greater flow of air over the wings.

Typical takeoff air speeds for jetliners are in the range of 240–285 km/h . Light aircraft, take off at around 100 km/h . Ultralights have even lower takeoff speeds.

The takeoff speed required varies with air density, aircraft gross weight, and aircraft configuration (flap or slat position, as applicable).

V₁, V_R and V₂ speeds

Operations with transport category aircraft employ the concept of the takeoff V-speeds, V₁, V_R and V₂.

These speeds are determined not only by the above factors affecting takeoff performance, but also by the length and slope of the runway and any peculiar conditions, such as obstacles off the end of the runway.

Below V₁, in case of critical failures, the takeoff should be aborted; above V₁ the pilot continues the takeoff and returns for landing.

After the co-pilot calls V₁, he/she will call V_R or "rotate," marking speed at which to rotate the aircraft.

The V_R for transport category aircraft is calculated such as to allow the aircraft to reach the regulatory screen height at V₂ with one engine failed.

Then, V₂ (the safe takeoff speed) is called. This speed must be maintained after an engine failure to meet performance targets for rate of climb and angle of climb.

Tyre design

An aircraft tire or tyre is designed to withstand extremely heavy loads for short durations.

The number of tires required for aircraft increases with the weight of the aircraft, as the weight of the airplane needs to be distributed more evenly.

Aircraft tire tread patterns are designed to facilitate stability in high crosswind conditions, to channel water away to prevent hydroplaning, and for braking effect.

Inflation

Aircraft tires are usually inflated with nitrogen to minimize expansion and contraction from extreme changes in ambient temperature and pressure experienced during flight.

Dry nitrogen expands at the same rate as other dry atmospheric gases (normal air is about 80% nitrogen), but common compressed air sources may contain moisture, which increases the expansion rate with temperature.

The use of an inert gas for tire inflation will eliminate the possibility of a tire explosion

Rolling resistance

Rolling resistance, sometimes called rolling friction or rolling drag, is the force resisting the motion when a body (wheel) rolls on a surface.

It is mainly caused by non-elastic effects; that is, not all the energy needed for deformation (or movement) of the wheel, is recovered when the pressure is removed.

The "rolling resistance coefficient" is defined by the following equation:

`F=C_rr N`

F - the rolling resistance force

- the dimensionless rolling resistance coefficient or coefficient of rolling friction (CRF), and

N - the normal force, the force perpendicular to the surface on which the wheel is rolling.

Usually airplanes have very low rolling resistance coefficient of such as 0.06.

Rolling resistance for an aircraft depends upon a lot of factors such as aircraft weight, runway condition, tyre conditions, tyre pressure and environmental factors (such as weather conditions)

Tyre pressure

Aircraft tyres are designed to withstand extremely heavy loads for short durations, with the number of tyres required increasing with the weight of the plane in order to better distribute the weight.

Tests of airliner aircraft tires have shown that they are able to sustain pressures of maximum 800 psi (55 bar; 5,500 kPa) before bursting.

There are 2 primary hazards associated with tyres:

1. Deflation;the tyre deflates in a controlled manner with minimal direct consequence to other systems.

2. Explosive break-up;the tyre (and sometimes the wheel holding the tyre) deflates or breaks-up in an uncontrolled manner with a significant probability of secondary damage to other unrelated systems.

These hazards are associated with 4 distinct periods of aircraft operation:

1. Ground operations e.g. taxiing
2. Take-off (up to gear retraction)
3. Post take-off (gear stowed)
4. Landing (to the end of the roll-out)

The various combinations of hazard and flight period can have markedly different influences, but all can affect operations to some degree.

Landing:

A number of issues can arise from landing with a deflated tyre:

Handling issues may arise during the landing roll-out phase, and in severe cases may cause the aircraft to depart the prepared surface.

Landing with a deflated tyre will put additional strain on the remaining tyres, with an increased potential for one or more to subsequently suffer an explosive deflation due to overstress. The implication for secondary damage to the aircraft is high and the potential for rapid aircraft arrest and evacuation is enhanced.

Brake forces

Bringing an aircraft to a safe stop is the most important part of a flight. In order to do this, pilots have a number of facilities available to them.

The brakes bear the brunt of the hard work with the spoilers and reverse thrust lending a helping hand to ensure maximum efficiency.

The autobrake system helps keep the deceleration nice and smooth whilst the anti-skid system reduces the distances needed to stop by modulating the brakes on individual wheels and stopping them from skidding.

Aircraft can also depart with part of the braking system not working.

By carrying out a performance calculation before every takeoff and landing, we ensure that the aircraft will stop safely in the given conditions, even at maximum takeoff weight.

A rough estimate for the maximum energy that the A380’s 16 brakes need to dissipate during landing can be obtained by calculating the kinetic energy of the aircraft (neglecting the effects of thrust reversers, air brakes, tailwinds, headwinds and runway slope).

kinetic energy (KE) is a function of mass (m) and velocity (v) according to the equation:

KE = ½mv²

Typical landing speed for an A380 is around 130kts to 140kts

The kinetic energy of the A380 during Landing is calculated as follows:

KE = 0.5 * 575,000 kg * (87.4556 m/s)² = 1.49131922169 x 10⁹ J = 1.49 GJ

To generate the necessary frictional forces and to handle this much energy within the length of a runway, large commercial transport aircraft typically require multiple discs per brake assembly and brakes on most, if not all, of their wheels.

6) Force and Power required to push / pull an aircraft by a towing vehicle.

The Embraer E-Jet family is a series of narrow-body short- to medium-range twin-engine jet airliners, carrying 66 to 124 passengers

For the calculation purposes the specifications E-195 model is used.

E-195 weight specifications.

The maximum take off weight is 52,290 Kg. Aircraft business is very stringent in safety measurements. Thus the aircraft is never operated at its maximum limitations.

Assuming the maximum aircraft weight during taxing is limited to only 95% of it's maximum take off weight, the design of aircraft is done at 54,900 kg

The main forces acting during taxing of an aircraft are

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and darg force (due to atmospheric air)

Rolling resistance of the aircraft

rr_a = (59400*0.006*9.81) rolling resistance coefficient of aircraft tires is taken as 0.006

Rolling resistance of aircraft = 3496.2840 N

Rolling resistance of the Tug ( Towing vehicle)

rr_t = (7620*0.01*9.81) rolling resistance coefficient of towing vehicle tires is taken as 0.01

Rolling resistance of tug = 747.522 N

Drag force while taxing the aircraft

The drag force D exerted on a body traveling through a fluid is given by

`D= 1/2 CρAv^2`

Where:

C is the drag coefficient, which can vary along with the speed of the body. Here it is assumed as 0.25

ρ is the density of the fluid through which the body is moving . Air density vale of 1.225 kg/m3 is taken

v is the speed of the body relative to the fluid. Taxing velocity is assumed to be 4.5 m/s

A is the projected cross-sectional area of the body perpendicular to the flow direction (that is, perpendicular to v). Frontal area is taken as 2 m2.

drag_force = (0.25*1.22*2*4.5*4.5)/2

Drag force = 6.17 N

Total force required by a tug to pushback the aircraft is = Rolling resistance of aircraft + Rolling resistance of tug + Drag force

= 3496.2840 N + 747.522 N + 6.17 N

= 4249.98 N

Assuming the wheels of the tug are 17.5 inches (0.4445 m) in diameter, the torque required by the Tug is

Torque required of the wheels of the Tug to pushback the aircraft = Force * Radius

= 4249.98 N * 0.4445

= 1889

Power required by the Tug to pushback the aircraft = Force * velocity

= 4249.98 N * 4.5 m/s

= 19.12 x 10³ W

= 19.12 kW

7) Electric powertrain with type of motor, it’s power rating, and energy requirement to fulfill aircraft towing application and the duty cycle range to control the aircraft speed from zero to highest.

Electric powertrain has three main components

Battery ------- Power Converter -------Motor

First motor ratings is calculated, then power converter ratings are calculated and finally battery capacity is also calculated

Motor Design

Torque calculation

The Electric Tug is assumed to have a gear ratio of 1:10. Thus the torque produced by motor is multiplied by a factor 10 at wheels.

Torque required of the wheels of the Tug to pushback the aircraft = 1889.11 Nm

Required motor torque = 1889.11 /10 = 188.911 Nm (Assuming there are no transmission losses)

Assumtions made

motor loss = 10%

Transmission losses = 20%

Required motor torque = 188.9 + 188.9(0.1+0.2)

= 245 Nm

Power calculation

The power required = 19.12 Kw

Assumptions made

motor efficiency = 90%

motor is designed to run at 80% of the full capacity for the safety purposes

Required motor power = 19.12/(0.9*0.8)

= 26.5 kW (or) 35.563906 HP

Thus the required motor specifications are

Torque rating = 245 Nm

Power rating = 35.56 HP

With these motor requirements the below mentioned motor is chosen and its specifications are given below

The Danaher Motion - 80V A/C Brushless

MOTOR SPECIFICATIONS
Power Train	80V A/C ELECTRIC
Traction Motor	Danaher Motion - 80V A/C Brushless
Output @ 1300 rpm	55 HP / 41 kW (Peak)
Torque (Electric)	210 ft lbs / 284 Nm

Power converter

Required power is 26.52 kW and the motor's full rated power is 41kW

Thus a DC-AC converter such as sine wave inverter with 41 kW handling capacity is chosen

Duty cycle calculation = 26.52/41 = 0.64

The duty cycle range is from 0 to 0.64%.

Battery Capacity

Assuming an average taxing time for E-195 aircraft is about 10 minutes. The energy required to move the aircraft for 10 minutes is calculated

Time = 10 mins (600 seconds)

Energy = power*time*60

= 26.5*10*60

= 15900 KJ

= 15.900 MJ or 4.4167 kWh

= 4.4167 kWh

Thus for operating the Tug for 10 minutes to tow one aircraft the energy required is 4.4 kWh.

Apart from towing the aircraft, the Tug should move from its parking place to tow the aircraft and then comeback from runway to parking place. To accommodate this travel an additional 0.6 kWh is added to required energy.

Thus for single towing operation the energy required is 4.4 kWh + 0.6 kWh = 5.0 kWh.

This is the energy required for single operation. Assuming a single full charge of battery the Tug can perform 25 Towing operations.

The required battery capacity is = 5.0 kWh * 25 = 125 kWh

Electric Powertrain

Motor specifications - Torque 284 Nm Power 41 kW (Peak)

Power inverter specifications - The duty cycle range is 0 to 0.64%. Handling capacity - 41 kW

Battery capacity - 125 kWh