Question

On average the mass of luggage carried on board an aircraft by a passenger is 32.7 kg. This includes checked and carryon luggage. The plane in question carries 332 passengers and always flies with a full load (pre-COVID conditions). The mass of the aircraft and passenger load (not including luggage) is 365,000 kg. The planes fly at an altitude of 29 km and at a velocity of 230 m/s. For the plane to fly at this constant altitude the lift force mist be equal to the downwards force caused by gravity (a simple view of flight). For this aircraft, the ratio of the drag force to the lift force is 0.21 and is constant. The plane will fly 4500 km (level flight). In this calculation only consider level flight and all processes as being isothermal.

1. The aircraft engine efficiency is 0.34 and the cost of aircraft fuel is $1.00/liter. The efficiency is defined desired output/required input. The energy content of the fuel is 46.5 MJ/kg and has a density of 0.804 kg/liter. At the end of the flight, there will be 10% of the initial mass of the fuel left in the airplane tank. Determine the mass and volume of the fuel, and the cost to complete this level (constant altitude) flight. Your approach should be based on an energy balance of the plane.HINTS:

• Are there any energy property changes in this process?

• The mass of fuel during this flight will be changing and affecting the total mass of the plane which affects the drag force on the aircraft.

• One means of including the effect of the varying mass of the fuel is to use the rate (or differential) form of the energy balance. In this case, one looks at an arbitrary position within the flight path and uses the rate form of the energy (work and heat) interactions () and rate of property changes like (if any). Alternatively, in differential) form, one can look at the incremental amount of energy transfers (δW & δQ) and the incremental change in system properties like dU (if any). There is no change in specific internal energy in this problem because it is an isothermal process. The benefit of the rate (or differential) form of the energy balance is that the parameters in the problem can be stated as a specific value at that a time snapshot within the flight. This allows one to recast the energy balance into an expression that could be solved for the change in the mass of fuel, for example over the flight distance. This usually involves integration or solving a differential equation

• If one knows how the mass of the fuel changes over the flight distance one can complete the energy balance between the initial and final states.

2. It is being proposed that a design in which the aircraft is powered by electrical motors and batteries be investigated for its feasibility. The mass of the motors is expected to be the same as that of the engines. The energy storage and mass of the battery packs needed to perform the flight as described in the question need to be determined. Note that in this problem the total mass of the batteries does not change during the flight. It is standard practice to discharge a battery to 20% to prolong battery life. Hence, we expect, the batteries will contain 20% of their energy capacity at the end of the flight. As a design starting point you should use the characteristics of the battery packs used in the current hybrid and electric vehicles, for example the Toyota brands or Tesla. Determine the required battery mass for the energy required for the entire flight. Based on your calculations is this a feasible design option?

3. Based on the battery specifications you selected in part B, determine the mass of batteries needed to supply the power to maintain the constant velocity and flight altitude in this problem. In this case, you will need to convert the energy balance from an energy statement to a power statement using the relationship between power and energy, that is differentiate the energy balance with respect to time. Is the answer for this part the same as in part B? Would this option be feasible from a power perspective?

4. There are also technologies such as flow cells or flow batteries or fuel cells that are used to store chemical energy or hydrogen to produce electricity. Using a high-level literature search to determine the performance, energy density of these technologies and compared it that for batteries you have chosen in part B. Would these technologies be an alternative to batteries?

Answer 1

In the Covid-19 world, those traffic jams risk far more than just irritation. Even with masks, packing people close together on an unventilated jet bridge is needlessly risky, especially if there’s a better way.

Michael Schultz, an engineer at Dresden University’s Institute of Logistics and Aviation in Germany, has been working on precisely this problem for a new paper. He and co-author Jörg Fuchte of German aerospace company Diehl Aviation hope to publish it in coming weeks.

In the normal boarding procedure, a passenger might come into close contact with five or six others. Introducing social distancing measures, where passengers remain about five feet apart, reduces that number down to one or two – not bad, but still too many. Changing the boarding procedure to board window seat passengers at the back first, for instance, however, can reduce the number of so-called “critical contacts” even further. Opening both the back and front door. “You can then separate the stream into two,” he says. Even if there is someone on the flight who poses a risk of infection, “at least one half – the front or the back – will never get in contact with that person.” At that point, “critical contact” drops down to “substantially below one, even with normal carry-on luggage”.

Jet bridges normally only allow access to either the front or back half of the plane, making it impossible to split the crowd in half. But sending passengers outside the terminal to board, by walking straight out onto the tarmac by the gate, as some budget airlines do already, solves this problem and more, by taking them into a low-risk, open-air environment where transmission is less likely.

The government has made it mandatory for all the passengers to go get screened thermally and have Aarogya Setu application installed. This will at least inform the authorities about the zone that the passenger is coming from and whether that zone is a highly infected one or not. To be sure, no one from a containment area is allowed to travel. Passengers have to sign an undertaking as well to declare that the passenger is not having any COVID-19 symptom.All passengers who will be boarding the flight should note that food will not be provided. Those who feel hungry should carry some dry food items in them that to only those who have to eat for some medical reasons or so. These measures have to be taken because even if a passenger wants to consume food, he or she will have to take the mask off to eat and there might be some possibility of transmission.