Who Says You Cannot Build Your Own Airplane? Series #12: Understanding Aerospace & Aeronautical Engineering And The Careers

So here we meet again after taking a rest for exactly a week. You do not want to hear the rain drenched me last night on my way back from a party. But then, I take that as a punishment for keeping my readers waited for long. So before heading straight to what we have to discuss about today, a brief recap of our previous should come for the sake of those that are just joining us, don't you think?

The aircraft instruments are responsible for aiding us with readings as we pilot the aircraft. They are categorised into three: The Pitch instruments (which include Attitude Indicator, the Altimeter, Airspeed Indicator and the Vertical Speed Indicator), the Bank instruments (Attitude Indicator, Turn & Bank Indicator and the Heading Indicator) and Power instruments (Tachometer and Airspeed Indicator). Most of the instruments are connected to the Pitotic Static System while others use the Gyroscope. How the instruments work and how they are used are fully discussed. Wy not check the full story below.

Full post here.

Just joining us for the first time? Now I tell you what, I am going to fine you for that but first check out the previous series: Series 1 | Series 2 | Series 3 | Series 4 | Series 5 | Series 6 | Series 7 | Series 8 | Series 9 | Series 10 | Series 11.

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On this series, we are going to look at what we call Aerospace Engineering and specifically Aeronautics and what it majorly entails as well as careers under it. Okay yeah we are building our own plane with our very hands which makes us Aeronautics engineers. But then there are so much to learn about Aeronautics engineering and aerospace in general. I have taken my time to ensure that each series we head into treats distinct topics that can get us well into the system. I think it is time we start facing the fact that we need to understand what we are getting into. If it was that easy, may be we could have had flying crafts during the era of Hercules. The ancient Greeks have been studying about these techs, Science did not just start in the 20th century after all. Let us get on it.

Aerospace & Aeronautic Engineering

Aerospace can be broken up into Aeronautics and Astronautics. Aeronautics is all about things that fly in air while Astronautics is about things that go into space.

Now, as you can imagine, Aeronautical engineers work planes, helicopters, missiles, fighter jets and so on. But because the discipline is based on Aerodynamic, you can see Aeronautics functions working on cars that shape to maximise the efficiency, they can work on boat interact, bullet trains that go up to 200 miles/hour and the latest kind - Hyperloop. I am sure many of us have known about hyperloop that has been in water right now, which will be a mode of transportation that will propel people like a vehicle through a tube and with maximum speed of about 800 miles/hour.

Subfields

So make sure that when you think of Aeronautic Engineering, think of the varying applications that it is applied to. There are many sub-fields that you can dive into when it comes to air or spacecraft when you work on the most specific actions of the vehicle. Some of the big ones that are talked about are

• Aerodynamics
• Propulsion
• Controls and stability
• Structures

Aerodynamics

Aerodynamics is of course when you study the moving air and the interaction with solid objects. after you through the basics of liquid dynamic like water going into pipe, then you enter the actual aerodynamics and you study the Subsonic Flow which is the airflow that is less than the speed of sound. The speed of sound is called mach 1. The aircraft we ride on, helicopters, certain military aircraft, or subsonic aircraft. The aircraft we ride on will go on typically Mach.8 or about 600MPH while the speed of sound is 770MPH.

So first you learn the Airfoil theory which is just about the theory behind airfoils, their shapes and how they produce lift. Two big aspects of this will analyse on Lift and Drag. Like we have learnt from the [previous series](, there are four forces acting on aircraft. Thrust that is produced by the propeller engines, Lift which is created due to the complex interaction between the air and the wing, Drag which is basically frictions from the air and Weight of the vehicle to the gravity.

Airfoils provide certain amount of lift based on their shape and then the physics behind the airflow interactions. you may be given some random object travelling through the air and asked to find the Drag on it or the Pressure at different points. Also when it comes to wings, what angle is the best for maximum lift and less drag. At some small arbitrary angle, you will see how the air splits at the front and then follow the curvature of the wing. This is ideal. But if we increase the angle too much, the flow becomes separated at the back and that will result in what we call a Stall. Recall we already discussed about that concept. The drag increases and the lift decreases which is obviously not what you want on an airplane. There is much more to this because if you been in air-shores you would have seen planes that fly upside down. To just know, this is very very basis.

Supersonic Air Dynamic

This is where an aircraft moves faster than the peed of sound. These are mostly military aircraft like fighter jets for defense purposes. Defense is a huge sector of aerospace engineering to get into.

So what happens with these speeds?

Well I am sure many of us know about Doppler Effect. As a source is moving and making noise, the relative frequency increases for the objects in front and decreases for the ones in the back.

Now what about the speed of sound?

Well, if you move slower than sound, the wave draws circularly and closer together in the direction of motion but not on top each other. Then, at a speed of sound, they actually bunch up on top of each other or constructively interfere. This combining of sound wave in front is extremely loud and is known as Sonic Boom which can break glass and shake windows while at thousands of feet in the air.

Then what about when object travels faster than sound?

Here the waves are created by tailing the aircraft. There is still a Sonic Boom but the waves combine constructively at an angle behind the aircraft rather than at the front. They might give you the Angle of Shock Wave which is what that is called and ask you to calculate the maximum number of speed that the aircraft is flying at. The faster the speed, the smaller that angle and that is something that we can calculate.

Now, at Supersonic speed, the drag force acting on the aircraft increases much faster as the aircraft speeds up. To compensate for this, supersonic aircraft are made to be narrow and have a slicker look to them.

Hypersonic

Now there are aircraft more powerful than the Supersonic. We call these the Hypersonic. They are the aircraft flying at Mach 5 or higher which is just under 4000 miles/hour. To be exact, Mach 5 is 3836MPH. To put that in perspective, you can fly from Los Angeles to New York in just under 40 minutes as supposed 5 hours.

Under this career, two big things you can do are Design or Testing.

Design

When you design, you might be developing the aircraft wing on a computer and its computation of full dynamic as discussed before. Then you can simulate how to respond to interaction with the air. As you handle the Supersonic or Hypersonic aircraft, the higher the speed, the more challenges you face.

Testing

You can be doing Testing using the wind tunnel for example. You put the physical structure in a large tunnel and run fast winds through it to see how it behaves as the computer assimilation predicted. In fact, the Parachute Testing in the wind tunnel with the testing of Parachute ships to see which is the best. But again, this can apply to cars, bikes and other vehicles to account for Aerodynamics. Now let us move on to Propulsion

Propulsion

This is where you obviously know the different types of Propulsion Systems used for an aircraft. The big ones we probably know are:

• Turboprop
• Turboshaft
• Turbofan
• Turbojet

So here is the picture of a Turbojet and basically how it works. Air comes in the front as the aircraft moves, it compressed or squeezed the remaining rotating blades which add energy to the fluid which causes pressure to rise. Then fuels at it and it is then on fire on the Combustion Chamber. It then travels through the Turbine which provides energy back to the Compressor. And then the air exit out at back at a fast speed and high temperature to provide thrust for the aircraft.

Now look at Turboshaft, Turbofan and Turbojet, you will see that they are very similar. The overall work of these isn't much different. I am sure most of us have seen the Propulsion System on an aircraft at least outside of it, let us just hint on what is going on inside.

So under the Aerodynamics of the Spinning Blades and the Compressor which like I said earlier, have a lot of stages to it;

• You are going to analyze the various reactions of the fluid as it moves through the various stages.
• You analyze the efficiency of the blades
• How you minimize the amount of blades needed.
• You analyze the Horse Power and much more.

Again, you may design these on the computer in your career or you do testing to see that all those specifications are met. Those are not the two jobs but are the big ones.

Now what about for Supersonic aircraft?

At supersonic speeds that are high enough, the engines does not require Compressor or Turbine air to increase the temperature and pressure of the fluid. If you remove those, we have what is called a Ramjet. These are best used for aircraft flying between Mach 3 and Mach 6. Supersonic aircraft like i said experience much more Drag t those high speeds, meaning the force pushing the aircraft to slow it down. Therefore you need that can supply enough force to compensate for this. Supersonic aircraft also fly at extremely high altitudes. That is altitudes where Air Density is much more lower. The engines must be able to compensate for that and intake a large amount of air because after all it is air that makes the Propulsion System to work.

Then, what if you want to get well into Hypersonic speeds?

Well, in this case you use a Scramjet. Okay brace yourself here. We actually do not know the maximum speed that this can go. If may be you are considering a Master's or even PHD and want to do research on Propulsion Systems, this is something you could do. Research on Hypersonic Engines.

One university way back put a model of Scramjet in a tunnel, added Hypersonic flow and then measured the overall force. They found out that the Scramjet was able to provide more thrust than the Drag it was subject to, meaning it was able to accelerate successfully and overcome Drag. This high speed is not easy to do and research is still being done. Theoretically, we predict these can travel between Mach 12 and Mach 24, we have not gotten that yet. So if you want to dive into Propulsion System and get us much faster speeds, this is something to look into. But remember, most job will involve designing and testing of the already known Propulsion methods.

Control And Stability

Well, we have just recently looked into this concept. How about we take a look at it this way: This is just about using inputs and doing Mathematical modeling to produce stable and desirable outputs.

For example, aircraft on Autopilot mode. The pilot may input some Heading or Direction and then the aircraft Control Systems have to be able to keep the aircraft headed in that direction. If you enable the Autopilot, you would not want a fast or abrupt changes because that may cause discomfort. You want a smooth transition to put the aircraft on the right course. Others involve making sure that the Control Systems produce stable outputs from the inputs it received. So one big thing to learn here is Coordinate Systems.

Coordinate Systems

If the aircraft is moving forward, we may call this the X direction which is parallel to the ground. And the direction of gravity called Y. That looks pretty convenient. But what the aircraft is increasing in altitude? Should we keep everything the same? Or may be we label the way it is accelerating (aircraft nose) as X. Now parallel to the ground like before but it is still convenient here, and then perpendicular to the ground will be Y. This is something important to know: The plane does not always go in the direction it is pointing. When the Angle of Attack is too big, the aircraft will stall. You will be doing lot of Coordination Systems and defining multiple axis for a given aircraft actions above and more.

Three of the most fundamental axis you will learn about are Yaw, Pitch and Roll. These are the three axis by which aircraft can be rotated. As we have discussed previously, Roll will happen when aircraft stops turning and then rolls to one side. Pitch will make the aircraft to point up or down while Yaw will turn the nose side to side.

How do these happen?
When the aircraft Roll, the flaps on the wings move in opposite direction causing air to push one up and the other down which causes a rolling motion. For yam, the rudder turns side to side allowing the aircraft to turn. And for Pitch, the two flaps near the rudder are turning in the same direction and then force the back either down or up respectively. Those are the three ways to rotate an aircraft.

And guess what? The Control Systems make sure that the changes and directional controls are handled carefully. You do not want to turn the flaps too much or the aircraft will roll too far which will obviously bring up problems. If the flaps change the Pitch too much, that could point the nose too high and increase the Angle of Attack and that could cause the aircraft to stall. The Control System keeps this all in check. It is not like you have a rope attached to the flaps and you manually roll the aircraft, there is an entire system that has to work just right. We also have unmanned aircraft which obviously have really great Control Systems as there is no direct pilot on the vehicle.

One area of research being worked on is Flexible Wings. Wings that can morph and change their shapes during flights. This is being investigated by NASA to greatly improve flight efficiency and performance. Control Systems will be required to change the wings during flight as needed. They take very similar control classes as electrical engineers because this is a field they can go into as well. So if the Control Aspects interest you the most, you can also choose Electrical and then search for Aerospace jobs.

Structures

This is much the same as for Astronautical Engineers, in fact you may take the same required courses when it comes to Structure. This is all about what you imagine. Making the structure of the vehicle to be bale to withstand all the forces it subject to. During flight, the wings are subject to a lot of forces. There are vibration, turbulence, etc. The aircraft has to be able to handle this. The basis of this involves learning about Strength, how the aircraft experience Fatigue overtime, the functions that may result to something bad with certain force, Sheering stress and all kind of forces that the structure can be subject to on what you will study. Although you diverge in specifically Aerospace classes, you will begin just like the Mechanical or Civil Engineers and have the same classes as them.

In your career, you can work on designing the structure of the wings. So instead of making Aerodynamic, you work in standard of Aerodynamic forces without breaking it. Or you can work on design if the structure of the cabin. Those walls are actually thinner than you may think and need to be designed just right. This is also a career you can see Civil or Mechanical Engineers doing because they learn about structures in their curriculum.

Overall, as Aeronautical Engineer, you are going to have bunch of classes that cover the basics of everything. Some basic structure classes, propulsion, controls and more. And then dive into one of those when you get Master's.

There are more Sub-fields to talk about.

• Design - which is more about analysing the aircraft as a whole and choosing the proper Landing Gear, Engine used, Passenger Cabin and so on.
• Or you can have option to take further Material Science Engineering classes. I did not mention it before but at Supersonic speeds, the friction from air molecules gets so intense that it can cause the aircraft to heat up to several hundred degrees. And Material Engineers may have to work on this and choose materials that can handle those temperatures but possibly, Aerospace Engineers can, as well.

Departing Thought

We will have to stop here. Remember, Aeronautical Engineers may accomplish more than you have imagined when it comes to careers. So be sure to look into everything. I am sure that if you have been following these series right from the beginning, you should have understood the mechanism behind the flight and how to handle a flight. You should be able to at least taxi the aircraft around the taxiways in an airport successfully without hurting the aircraft. Buddies, we have covered a lot. And we have mountains to climb ahead. Buckle down, we are getting there!

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References

• Aerospace & Aeronautic Engineering
• Aerospace Engineers
• Aerospace and Astronautical Engineering
• Propulsion

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Previous Lessons In The Series

• Series #11: Yo Nigga! You Don't Mess With Flight Instruments
• Series #10: Pilot Navigation - Flight Planning, Flight Logs, Map Readings, Correcting Heading Errors & Actions To Take When Lost
• Series #9: Understand The Concept Of Flight Approach And Landing
• Series #8: Understanding The Airport Circuit, Control Zone & Dealing With Flight Conditions Illusions
• Series #7: Understanding The Aerodynamics; Spin, Spiral, Slip And The Concept Of Take-Off
• Series #6: Understanding The Concept Of Slow Flight and Stall
• Series #5: Understanding The Flight Maneuvers; Climbing, Descending & Turns
• Series #4: You've Got Attitudes, Aircraft Got Some Too
• Series #3: Understanding How Jet Engines Work And Effect Of Atmosphere In Flight
• Series #2: Understanding The Thrust Mechanism And How The Engine Works
• Series #1: Understanding The Mechanism Behind Airplanes And The Misconceptions

Till we meet again on my next post, well I am not changing my name. I am @teekingtv and I write STEM! THANK YOU FOR READING. GOD BLESS.

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