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

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 fuel².

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.

Maximum zero fuel weight (MZFW) is the maximum weight allowed before usable fuel and other specified usable agents (engine injection fluid, and other consumable propulsion agents) are loaded.

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 such as engine oil, engine coolant, water, unusable fuel and all operator items and equipment required for flight but excluding usable fuel and the payload.

Payload:

t 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 off³.

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 land³.

The following image depicts takeoff weight components.

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.

Maximum takeoff weight (MTOW) Of different airplanes:

2. Is there any difference between ground speed and air speed?

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

Difference between ground speed and air 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. Why is it not recommended to use aircraft engine power to move it on the ground at Airport?

For movement on the ground the aircraft uses it own engine power, which is called taxiing.

Taxiing, though, specifically involves the use of an airplane's own propulsion system to move while on the runway.

Towing

Although many aircrafts are capable of moving in backward using reverse thrust, as result the jet blast or prop wash might cause damage to the terminal building or equipment. Engine close to ground may also blow sand and debris forward and then suck them into the engine, causing damage to the engine. Therefore there are pushback trucks in the airport. A pushback truck lifts the front weel of the aircraft, their role in most airports is to move the aircraft away from the parking spot on to the taxiways, which is called towing.

Advantage of Towing:

1) Effectively a loss of control can happen, especially during high power engine running. Damage can occur to the aircraft itself, other aircraft nearby or to airside structures.
ii) There is a risk of injury to ground support personnel who may be in relatively close proximity to the aircraft.
iii) It is easier for truck driver to see the surroundings better than the pilot sitting in the cockpit with limited window. The pushback driver knows the airport better than the pilot.
iv) It also saves fuel

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

Four Phases of flight:

In aviation, pushback is an airport procedure during which an aircraft is pushed backward away from its parking position, usually at an airport gate by an external power. Pushbacks are carried out by special, low-profile vehicles called pushback tractors or tugs.

Although many aircraft are capable of moving themselves backward on the ground using reverse thrust (a procedure referred to as a powerback), the resulting jet blast or prop wash would cause increased noise, damage to the terminal building or equipment, and hurt airport staff due to high-speed debris. This debris would also be sucked into the engine, as it is in normal use, and cause excessive wear - a major cause of wear on aircraft engines is during ground use. A pushback is therefore the preferred method when ground-handling aircraft.

Pushbacks at busy aerodromes are usually subject to ground control clearance to facilitate ground movement on taxiways. Once clearance is obtained, the pilot will communicate with the tractor driver (or a ground handler walking alongside the aircraft in some cases) to start the pushback. To communicate, a headset may be connected near the nose gear.

Since the pilots cannot see what is behind the aircraft, steering is done by the pushback tractor driver and not by the pilots. Depending on the aircraft type and airline procedure, a bypass pin may be temporarily installed into the nose gear to disconnect it from the aircraft's normal steering mechanism.

Once the pushback is completed, the towbar is disconnected, and any bypass pin is removed. The ground handler will show the bypass pin to the pilots to make it clear that it has been removed. The pushback is then complete, and the aircraft can taxi forward under its own power.

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

1.take off power:

An airplane is motionless at the end of a runway. This is denoted by location O. The pilot releases the brakes and pushes the throttle to maximum takeoff power, and the airplane accelerates down the runway. At some distance from its starting point, the airplane lifts into the air. The distance the airplane cover along the runway before it lifts into the air is called the ground roll (sg). The total takeoff distance also includes the extra distance covered over the ground after the airplane is airborne but before it clears an obstacle of 50 ft for military aircraft and 35 ft for commercial aircraft. This is denoted by sa. The sum of sg and sa is the total takeoff distance.

• As the airplane accelerates from zero velocity, at some point it will reach the stalling velocity VStall
• The airplane continues to accelerate until it reaches the minimum control speed on the ground, Vmcg. This is the minimum velocity at which enough aerodynamic force can be generated on the vertical fin with rudder deflection while the airplane is still rolling along the ground to produce a yawing moment sufficient to counteract that produced when there is an engine failure for a multiengine aircraft.
• If the airplane were in the air (without the landing gear in contact with the ground), the minimum speed required for yaw control in case of engine failure is slightly greater than Vmcg This velocity is called the minirnum control speed in the air, Vmca
• The airplane continues to accelerate until it reaches the decision speed, V1. This is the speed at which the pilot can successfully continue takeoff even though an engine failure (in a multiengine aircraft) would occur at this point. If an engine
fails before V1 is achieved, the takeoff must be stopped. If an engine fail after V1 is reached, the takeoff has to be completed.

• The airplane continues to accelerate until the takeoff rotational speed, VR is achieved. At this velocity, the pilot initiates by elevator deflection a rotation of the airplane in order to increase the angle of attack and to overcome the weight. Attention should be paid not to stall.
• the angle of attack necessary to overcome the weight may not be achievable because the tail may drag the ground. If the rotation of the airplane is limited by ground clearance for the tail, the airplane must continue to accelerate while rolling along the ground after rotation is achieved. This speed is called the minimum unstick
speed, denoted by Vus.
• For increased safety, the angle of attack after rotation is slightly less than the maximum allowable by tail clearance, and the airplane continues to accelerate to a slightly higher velocity, called the lift off speed, denoted by VLO. This is the point at which the airplane actually lifts off the ground. The total distance covered along the ground to this point is the ground roll sg.
• Generally VLO=1.1 Vstall

2. tyre design:

Why are tyres important in Aircraft?

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.

A Boeing 737NG & 737MAX uses 6 wheels, Boeing 787 uses 10 wheels, Boeing 777 uses 14 wheels and Airbus A380 uses 22 wheels. Aircraft tyres work under extreme conditions, carrying up to 340 tons and accelerating at over 250 km/hour at takeoff, in addition to enduring varied environmental stress when in flight and taxiing.

Design and Construction of Aircraft tyre

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.

Load Rating – Load rating is the maximum permissible load at a specified inflation pressure.

Ply Rating – Ply Rating is used to identify the maximum recommended load rating and inflation pressure for a specified tyre. It is an index of tyre strength.

Speed Rating – The speed rating is the maximum takeoff speed to which the tyre has been tested.

Skid Depth – Skid depth is the distance between the tread surface and the deepest groove as measured in the mould.

Aircraft tyres must have an approved speed and load rating and have sufficient clearance when retracted through landing gear to allow for tyre growth. Tyre growth is the increase in the size of the tyre due to centrifugal forces at high speed.

Aircraft tyres may be Tube-type or Tubeless

Tubeless tyres are more advantageous over tube-type. There is no longer the use of tube-type tyre in recent aviation. Nowadays all airliners are using tubeless tyres. Tubeless that are meant to be used without a tube has the word TUBELESS on the sidewall of the tyre.

Aircraft tyres may be Radial or Bias

Almost all airliners are using Radial tyre. Bias is an older design, and it’s mainly used for road vehicles. Radial tyres have the word RADIAL on the sidewall. Radial tires are more expensive than bias-ply tyres. Radial tires are in demand because of their lower life cycle cost and long term value.

Are aviation tyres are conductive?

Yes, Today’s tyres are conductive. Aircraft tyres are manufactured with tread rubber with conducting compounds to permit earthing of static charges.

In early days when tyres were not sufficiently conductive, aircraft used to have a conductive strip hanging down from the axle of the landing gear. Upon landing, this strip would be the first part of the aircraft to touch the earth. This discharges any static electricity accumulated on the outer surfaces of the aircraft. Now you don’t see them anymore.

What is the purpose of Chines in aviation tyre

Chines are also called deflectors. Chine tyre used on the nose wheel of aircraft, specially fuselage-mounted jet engines. It diverts runway water away from the engine inlets.

Chines are circumferential protrusions that are moulded into the sidewall of nose tyres that deflect water sideways to help reduce excess water ingestion into the engines. Tyres may have chines on one or both sides, depending on the number of nose tyres on the aircraft.

Aircraft Tyre Standards

Each tyre manufacturer produces their own designs of the tyre with different tread patterns, wear patterns, wear limits etc, and in some cases, different names for the same part of the tyre. But all tyres must meet the approved standards before being accepted by the FAA or CAA.

All commercial aircraft tyres approved under FAA Requirement Technical Standard Order (TSO) C62. A TSO is a minimum performance standard for specified materials, parts, and appliances used on civil aircraft.

Rolling resistance:

• In addition to the familiar forces like thrust, weight, lift, drag there is a rolling resistance force FR caused by friction between tyre and ground. When aircraft is towing or taxiing to push it into the runway or when takeoff roll is happening, the rolling resistance force act against the traction force of the aircraft.
• This rolling resistance force depends on many factors like surface of the road, roughness of the road, dry or wet condition of the road, tyre pressure, tyre material, tyre temperature, thread pattern of the tyre etc, which determines the rolling resistance force.
• The rolling resistance coefficient is denoted by μrr">μrrμrr. The values vary with speed. Tire pressure increases its value decreases need to carefully choose value as per typical cases under consideration

• 

Airplane Tires Don’t Explode on Landing Because They Are Pumped!

They're like the tires on your car—but way stronger.

when an airplane lands is a blowout. Think about that: Again and again, the tires hit tarmac at 170 miles per hour and bear the weight of a modest office building.

Aircraft tires are amazing when you think about it. The typical airliner tire can handle a 38-ton load. It can meet the ground 500 times before needing a re-tread, a refresh it can take on seven times in its life.

A Boeing 777 uses 14 tires, Airbus' A380 carries 22, and the enormous Antonov An-225 demands 32. The key to their remarkable durability is maximizing the air pressure, says Lee Bartholomew, lead test engineer for Michelin Aircraft Tires. The high-flying rubber is typically inflated to 200 psi, roughly six times what you put in an automobile tire, and the tires on an F-16 fighter are pumped to 320 psi. “It's really pressurized air that's so strong,” he says

The tires themselves aren't terribly large--- a Boeing 737 rides on 27x7.75 R15 rubber. In English, that means it is 27 inches in diameter, 7.75 inches wide, and wrapped around a 15-inch wheel. The sidewalls aren't terribly thick, and the strength of the tire lies in the cords embedded below the tread, Bartholomew says. They're typically nylon, and more recently a variety known as aramid. Each layer of the casing contributes to its load bearing and air pressure resisting capabilities. Of course, tires can fail, especially when under-inflated or overloaded. Treads can come off and casings can blow out.

n the first moments after a plane touches down, the tires are skidding, not rolling. The airplane essentially drags them down the runway until their rotational velocity matches the velocity of the plane. That's why they smoke upon landing, and why Michelin uses grooves instead of the block patterns seen on your car's rubber---blocks would simply break off. (Most tire wear comes from this moment of contact---where the rubber meets the runway.) The stoutest tires are rated for speeds of up to 288 mph.

To develop a new sort of tire, or test a tweak, Michelin starts with computer simulation, followed by prototyping. Then it tests how the tires do when they're overloaded or pushed past their speed limit, on simulated takeoffs, landings, and taxiing. Like everything in aviation, tires must meet specific and demanding rules---for example, a tire must withstand four times its rated pressure for at least three seconds.

Weight and Tire pressur of different Airplanes:

brake forces:

Aircraft brakes stop a moving aircraft by converting its kinetic energy to heat energy by means of friction between rotating and stationary discs located in brake assemblies in the wheels.

A

Brakes provide this critical stopping function during landings to enable airplanes to stop within the length of the runway. They also stop aircraft during rejected takeoff events, in which an attempted takeoff is canceled as the airplane is rolling down the runway before it lifts off from the ground due to engine failure, tire blowout, other system failure or direction from air traffic control.

Aircraft brakes also prevent motion of the aircraft when it is parked, limit its speed during taxiing and can even help steer the aircraft on the ground by applying different levels of braking force to the left- and right-side brakes.

Aircraft brakes work in conjunction with other brake mechanisms such as thrust reversers, air brakes and spoilers. Thrust reversers are surfaces that are deployed into the path of the jet blast from the engines to redirect propulsive thrust in a direction that opposes the motion of the aircraft. Air brakes and spoilers are flight control surfaces that create additional aerodynamic drag when deployed into the path of air flowing around the aircraft.

Six Steps of braking when landing:

1) Plan Braking For Your Desired Exit

This may sound self-explanatory, but never brake too much or too little for your runway exit. If your turnoff isn't for a few thousand feet, there's no reason to apply maximum braking and force airplanes to go-around as you slowly taxi down the runway.

The opposite holds true for a short field or immediate turnoff. Apply smooth, constant brake pressure and never take a turn too fast.

Boldmethod

2) Don't Keep Your Toes On The Brakes Before Touchdown

Any brake pressure prior to touchdown puts you at risk for blowing a tire. With no free movement your wheels will skid, and at a minimum, you'll be replacing tires when you get back to the hangar.

Corey Komarec

3) Locked Tires + Wet Runway = Reverted Rubber Hydroplaning

Reverted rubber hydroplaning happens when your tires lock up, the rubber begins to melt, and trapped water under the tire turns into steam. When it happens, you're riding on steam, and melting your tires in the process.

Use light brake pressure, use aerodynamic braking to keep maximum weight on your landing gear, and never lock up your brakes on landing to prevent this.

4) Most Jets Have Anti-Lock Braking Systems, Just Like Your Car

The anti-skid system releases pressure on the brakes when it senses the wheels are starting to skid. When they spin up again, it re-applies brake pressure. This release and re-application of brake pressure happens very quickly, much like what happens with your car's anti-lock brake system.

If you feel the anti-skid system kicking in, let it do its job. Don't release full brake pressure if you need to stop.

5) Flying A Trailing-Link Gear? Avoid Early Braking

Trailing-link gear are designed with a flexible, L-Shaped arm and pivot point, connected to an oleo strut shock absorber. As the oleo strut compresses, the L-shaped bracket functions as an extra shock absorber, moving the tire back to upward. This helps smooths rough impacts with the runway.

As the oleo strut compresses, the L-shaped bracket functions as an extra shock absorber, moving the tire back to upward. This helps smooths rough impacts with the runway. Because full weight isn't initially applied on the wheels, avoid substantial braking until the airplane "settles" or you'll risk shredding the tires as they lightly skim the ground in a locked state.

6) Short Field Landing? Use Full Aerodynamic Braking

Once you touchdown, you want to use maximum aerodynamic braking. After you touch down, slowly start pulling back on the yoke, being careful not to lift back off. As you increase your aerodynamic braking, you keep more weight on your main gear. That, in turn, makes your brakes more effective, because you can apply more brake pressure before your wheels lock up.

Be gentle as you apply the brakes, then start increasing braking pressure to slow down. It's easy to lock up your wheels when your ground speed is still high, and you're wings are producing a lot of lift. Keep pressure on the brakes until you know you're slow enough to make your taxi turnoff, then gently start to let up on the brakes. Smooth application of your brakes is the key to a good landing rollout.

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

Push and pull an aircraft by a towing vehicle have two forces.

There is no hill climbing force because towing vehicle run at horizontal movement only

1. Rolling Resistance Force(Frr)

2. Aerodynamic force (Fad)

1. Rolling Resistance Force(Frr):

Frr= Mrr*m*g

2. Aerodynamic force (Fad):

Fad=1/2*P*A*Cd*V^2

Calculations are attached in Excel and matlab screenshot attached below:

Rollind Resistance Force(Frr)

Aerodynamic Force(Fad)

Total power in KW

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)

B. Also, Design the parameters in excel sheet.

Draw a block diagram of powertrain.

Here i have DC7 block for as per our motor specifications

Results: