Airframe Considerations (a brief history and diagram of flight characteristics)

Hi Anya Foxy here with Foxflite! I am very excited this week to bring you part B. of the XP scratch build project! When building an aircraft there are a number of things to keep in mind in regards to design of your aircraft. What works best for one aircraft might not work as good for another aircraft so as a hobby builder you need to take this into consideration each step of the way!

Over the past sixty years or so jet designs have been getting increasingly more sophisticated and more powerful. This stems from the need to increase range, cruising altitude, cruising speeds and outward control of the aircraft.
Starting back with the Wright brothers Orville and Wilbur, there was this initial push to achieve manned flight! this has been a dream of man since before the time of ancient Greece when wise men regaled stories of Icarus and cited that it would not be possible to achieve flight.
The first flight of the kitty hawk which lasted only a few brief moments would revolutionize a bold first step into the modern age of flight. Over the next several decades this would lead to the advent of the biplane which originally was used as a scout plane in the early start of world war one. The aircraft then took another tiny step forward when a pilot brought his rifle along to shoot down German pilots.
This was the birth of air combat in it's early infancy.
Later efforts to improve upon the aircraft led to larger air conflicts and dogfighting in the skies over Europe.
During the second world war a race was on to build the most advanced aircraft giving birth to much loved and much feared designs as the Messerschmidt and the spitfire which became big players in what was at the time considered cutting edge aeronautical engineering.

In 1928 Air Commodore Frank Whittle an RAF air force engineer was credited with coming up with the first jet engines. His works were a precursor to Dr. Hans Ohain's work during the late stages of world war two.
In 1935 Ohain started his prototype of the jet engine and by this point surpassed the prototype stage to produce the Henkel HeS-3

Enter the jet age... Various designs have since then come available starting initially with the swept wing designs and then delta wing aircraft. Finally progressing into the era of the modern jet.
Each design carries with it a unique set of characteristics of which each is unique and many form the backbone of military aviation. Engine designs have also come along way since the turbojet.

      

 

Initially during the early phases of experimental jet construction not much was really known about how designs would affect the overall flight characteristics of the craft. Aircraft designs almost directly pushed away from broader more stable wings which caused a great deal of lift and stability for more aerodynamic swept wing designs to allow for higher speed. This sacrificed overall stability in favor of maneuverability and speed. 

This also lowered radar profiles drastically, The cockpit was also pushed forward to allow for better vantage using line of sight. This proved a significant improvement on against the more classic forward prop designs which had somewhat limited visibility due to the bulky forward engine compartments.

continuing on. 

When you take into consideration the shape and structures of aircraft it boils down to 

the physics of aircraft flight. One has to do the math and decide what is best for them personally. Individual preference is key. 

On a physics standpoint air is considered a fluid because it in essence acts similarly and when an object passes through the air it creates drag behind the object (fluid states are characterized by the scientific fact that they do not hold a resistance to force for any appreciable length of time, this means that forces can act on them creating dramatic effects which are observable under the right conditions an example of fluid dynamics can be listed as when you pull the plug on a bath tub or watch a motorboat along a busy river or lake as it cuts a wake. in the case of air however it is aerodynamic drag as opposed to hydrodynamic drag that follows a craft in the same function as a wake but on a much different scale. 

Being that the air is thinner then water it requires a different set of characteristics entirely.

 "Bernoulli's principle states that within an airflow of constant energy, when the air flows through a region of lower pressure it speeds up and vice versa.^[43] Thus, there is a direct mathematical relationship between the pressure and the speed, so if one knows the speed at all points within the airflow one can calculate the pressure, and vice versa. For any airfoil generating lift, there must be a pressure imbalance, i.e. lower average air pressure on the top than on the bottom. Bernoulli's principle states that this pressure difference must be accompanied by a speed difference." (quoted from wikipedia) 

P₁ + ρgy₁ + ½ρv₁² = P₂ + ρgy₂ + ½ρv₁²

 

Lift. Lift is a key factor in flight, As air passes over a surface it creates drag and divides the fluidity of the air which is notably seen in birds. When you look at a wing you will be able to observe a notable characteristic on the leading edge of the wing that sweeps backward in a broader arch then the underside of the wing

this is to create a difference in pressure which is much faster and more constricted on the top side of the wing then the underside of the wing while at the same time producing an opposite force with the weight of the wing on the underside and a much higher pressure while less constricted that is directed downward generating lift 

(note that airflow must remain at a constant)  this is an observable effect when you watch an eagle gliding on the wind currents during a gusty day.

The other considerations to take into account regarding aerodynamics are, Angle of attack, Centre of gravity and overall thrust to weight ratio. When you apply these factors you should have a successful build, Just remember, Stick with what works! 

I am Anya Foxy logging off for today! Whew *falls over*