# Tag Info

67

You were born 100 years too late. In order to be an improvement over existing designs, airplanes become ever more complex and every detail is optimised over years and years. The days when someone like Robert Hall or Kurt Tank would design and test fly their designs are long gone. The best you can do is to design an experimental aircraft and maybe market it ...

35

Rather than being concerned with titles, let's take a look what's involved in designing/analyzing/certifying a modern airplane: External aerodynamics: deduce the aerodynamic characteristics and propose changes in outer model line as required to achieve the desired characteristics. Skills: applied mathematics, aeronautics engineering. Flight science: deduce ...

15

I'll address the question in the title: how to get into actually designing an entire aircraft. Not every component, but making the major, visible decisions. Such jobs do exist, but they aren't easy to get. Design is an iterative process that goes continuously more in-depth on every step. It begins with a requirements document, which are responded to with ...

6

Air pressure reduces with altitude, so while an individual molecule is striking the the aircraft at 100kt, there are fewer of them. This means there is less pressure placed on whatever surface is being struck. The difference in indicated speed is simply one of a physical limitation with the air speed indicator - air speed indicators rely on dynamic pressure/...

5

The frontal surface is indeed used for the drag coefficient of cars. For airplanes, however, almost* all coefficients use the wing area as their reference. This makes sense exactly because it allows to express L/D as c$_L$/c$_D$. * For the nitpickers: Control surface hinge moment coefficients use the area of their respective control surface, not the wing ...

5

Think of it this way. Your airspeed indicator is not directly measuring the distance traveled of any object, aircraft nor air molecules, over time. Your airspeed indicator is a pressure sensitive device that measures ram air pressure (dynamic pressure) versus static pressure. It converts that measurement into a meaningful value of airspeed. That ram air ...

4

Not really. First, the 'legal' reason: the flight manual doesn't offer this method. So you are not supposed to do it. Second, there is a technical reason: MiG-21 had so called 'floating flaps' (as they call it), which are held down only by hydraulic pressure. The pressure is set such that the air dynamic pressure would retract the flaps as the airspeed rises ...

4

Not for modern airplanes. Let's look at an example. Take a small airplane, the Cessna Skyhawk. Even on an airplane that small, Cessna doesn't make all of the components itself. For example, the engine is made by Lycoming, the avionics are provided by Garmin, the propeller is made by McCauley etc. There isn't a position at Cessna involved in the design of all ...

4

Yes, rounded wings have been tested in the past. Probably the most famous example is the Vought XF5U "Flying Flapjack". They work perfectly fine. However, the design as pictured does have some flaws. Efficiency The lower the aspect ratio (i.e. wider front-to-back in comparison to their length left-to-right), the more inefficient the wing. This is ...

3

Probably the last guy that was able to do that successfully was Burt Rutan. A person whose history is worth studying if you are interested in this sort of thing. Designing a complete aircraft from scratch today is far less likely then designing a complete car.

3

If to see an aircraft as a vehicle that is able to fly by gaining support from the air, the definition may cover also drones of all kinds. Then a realistic way would be to create a startup that designs a drone. For instance, I know a Swiss startup that designed unusual VTOL fixed wing drone offering much more endurance than its helicopter-like competitors. ...

3

Why aren't propellers way larger than they typically are? There are some "propellers" these days with a 400 foot disk diameter, known as windmills. But, they are doing their best to extract energy from the airstream and here lies the issue. "Relative wind" is conveniently used to combine the net direction and force of two aerodynamic effects, but let's ...

3

I would recommend the use of Aeolus ASP for aerodynamic shape optimisation. Edit: I am not associated with the software in any way. I had found its shape optimisation features useful for an assignment at my university.

2

I worked at Mooney for 11years, 6 as the Director of Engineering after Roy Lopresti left the company. Art Mooney asked Al to design the wood spars so he could build them on a flat table. This resulted in t iconic and characteristic "Mark" of the M20 Type.

2

The provision of lots of flaps settings is motivated in part by the desire to provide as many profile optimizations as possible. Generally, the less the flap extension for takeoff, the more efficiency you have in a departure plus better engine failure performance, but you need the longest runway, so you would use the least extension allowable for a given ...

2

Resistance is a term used in politics and electric circuits. We here talk of drag. Your induced drag equation uses speed where the lift coefficient belongs: $$c_{Di} = \frac{c_L^2}{\pi\cdot AR\cdot\epsilon}$$ What is missing now is the zero-lift drag which is the dominant contributor to overall drag at high speed. From your top speed result this seems to be $... 2 Dynamic pressure is $$q = ½\varrho v^2$$ where$q$is dynamic pressure,$\varrho$is density and$v$is velocity (a.k.a. true airspeed). The important bit here is that it is proportional to density and since density and pressure are closely related and pressure decreases with altitude, so does density For the intuition of particles hitting the surface, ... 1 TL-DR: IAS is not about speed but about dynamic pressure. You can read it as "This is how fast I would need to fly at sea level standard conditions in order to get the same dynamic pressure" As Jan Hudec pointed out already, indicated airspeed is computed from dynamic pressure. That itself is computed from total (i.e. stagnation) and static ... 1 You can use the Lifting Line Theory to first calculate the downwash at each spanwise station, which are then converted to the induced AOA ($\alpha_i\$). The sectional moment coefficient and lift coefficient are: $$c_m = c_{m_0}+c_{m_\alpha}(\alpha-\alpha_i)$$ $$c_l=c_{l_0}+a(\alpha-\alpha_i)$$ To get the total moment of a straight tapered wing (about the root ...

1

At one step remove, technical computing. Over the four years I in technical computing at BAE SYSTEMS, I was helping design: Operational research simulation Observe Orient Decide Act loops Sensor integration Genetic design of wing shape Simulated annealing of processor allocation Structural integrity modelling Radar cross-section estimation Autonomous air ...

1

No. MiG-21 (any modification) didn't need it and didn't have it. With its low-aspect-ratio delta wing and most mass concentrated in the centre, it was agile enough with standard ailerons. The elevator had a single hydraulic booster driving both halves of the stabiliser. Differential stabiliser was used on MiG-21's successor, MiG-23. That one had no ailerons ...

1

The Doak VZ-4 twin ducted propulsor flew in 1958, the Bell X-22 took that up to four in 1966. So yes, people have been thinking about it for over half a century. Analogously to any tailless aircraft, the side-by-side twin is sensitive to CG in vertical mode and trim must be closely maintained. Although not ducted, the Boeing V-22 Osprey convertiplane suffers ...

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