Skylap student notes

Flight has always captured our imagination. Early aircraft designers used all kinds of materials and designs to achieve this dream.  A key to their success was understanding how things work by making and testing ideas, and not being afraid of failure.  In this project you will need the same approach.

Before solving any problems, all designers and engineers start by exploring and learning the basics. It’s good to be curious, so let’ start exploring or you can go straight into the making.

 

Background :

Over 2000 years ago the Chinese invented the first kites using bamboo and silk which showed that flight in some form might be possible.  Later, in the 15th Century, Leonardo da Vinci did drawings of a machine strapped to a human to copy the flapping action of a bird. 

In 1010 AD Eilmer of Malsbury, an English monk, strapped on some wings he designed and jumped from a watchtower to test his ideas.  He did fly a bit, but the landing was rough with two broken legs.  This didn’t worry him and wanted to make more attempts at flight.  His boss stopped him.

In the 1890s Otto Lilienthal showed the world that unpowered human flight was possible.  With his apparatus attached he made approximately 2000 takeoffs, some from a 15 metre high  hill he made himself. 

His final test flight ended in tragedy. He died from spinal injuries sustained when he and his glider struck the ground.  His contribution earned him the title ‘The Father of Flight’.

In 1903, after extensive research, the Wright brothers made history when their aircraft remained in the air for 12 seconds going nearly 40 metres.  Several attempts later they managed to fly 260 metres in just under a minute.  This was the start of the aviation industry.

The natural world has been good at flight for millions of years, showing that there are many solutions.  Insects often have four wings and fly very differently to birds which have two.  The hummingbird creates lift on boht the up and down strokes of their wings, but other birds create lift only on the downstroke. 

 

There are also flying mammals, flying fish and many years ago, even flying reptiles.  Nature has given us many examples of flight.  Even some plants have seeds that make use of the wind to fly further away.       

Early aircraft designers had to learn about the relationship between strength and weight.  It turned out to be very important.  To achieve flight an object needs to be light without sacrificing too much strength – in fact the structure of every flying animal seems to be as light as it can possibly be whilst being only just strong enough to do the job. 

Strength can in fact be maintained while reducing the weight of a structure.  And nature has shown the way.  It comes down to the distribution of matter. 

The cross section of a bird’s wing shows cavities with diagonal structures.  These holes actually increase the all-important strength to weight ratio. It may be slightly weaker than a solid bone, however it is many times lighter.

Strength on its own in any structure natural or man-made is not actually important.  What matters is strength to weight ratio

 

Early aircraft were made of canvas stretched over wooden frames which was light, but when better engines meant they could go faster, something stronger was needed and it didn’t matter if it was a bit heavier. 

Aluminium was the answer.

 

A wing’s cross-sectional shape is called an aerofoil and it causes the air going over the top to go at a different speed to the air passing under it. This creates lower pressure on the top surface and higher air pressure under the wing pushing it upwards.  This helps create lift.

The angle of attack of a wing is actually more important.  When a wing points up slightly, more air pushes on the underside of the wing creating lift. Increasing angle of attack will increase lift, but only up to a point.  If angle of attack is too big then the plane stalls and loses all lift

Lift only works if there is airflow over the wing, and to achieve this the plane needs to be forced through the air with a propeller motor or jet engine.

 

Drag is the force of the air on the aircraft as it flies.  It works against thrust.  The bigger the plane, the more drag there is.

There are three kinds of motion that every aircraft needs to be in control of: roll, pitch and yaw. Each of these motions is controlled by a particular control surface.

The Ailerons control roll.  They always work in opposite directions so that if one is up then the other is down. 

The rudder controls yaw which is the horizontal rotation of the aircraft. 

The elevators control how much the aircraft is pointing up or down, called pitch.  When the elevator is up then the front of the pane pitches upwards which also increases the angle of attack.  Angle of attack is cotrolled by the elevator.

Your task:

Make a working model aircraft using the materials provided.

Test the aircraft on the PowerAnchor and modify it to achieve one of the following challenges.

  • Make the fastest plane
  • Make the highest flying plane

 

Use the materials provided and test your plane on the PowerAnchor.  Your aircraft needs to be able to take off from the ground and land without crashing.

Make changes to your aircraft that you think will improve it .

Making:

Before doing any experimentation it’s a good idea to make a first aircraft that you know will work.

You will need:

  • Flat balsa wood
  • Long square section balsa wood
  • Plane connectors
  • Motor and hook-up cables
  • Wheels and axle
  • Scissors or craft knife
  • Ruler and pencil

 

Fuselage:         Cut the long stick of balsa to 300mm

Wing:              Cut the flat balsa to 300mm x 75mm

Elevator:          Cut the flat balsa to 80mm x 20mm

Rudder:           Cut a 20mm x 20mm piece from the flat balsa

Connect the hook-up cables to the motor

Push all the parts together with the connectors as shown.

Tilt the elevator to create an angle of attack on the front wing .

Testing your plane:

Hook up your plane to the PowerAnchor by connecting the tether cables to the wing at the tabs.  Use the clips to also hold onto the motor cables.

Modifying your plane:

The key to this project is making your own variations.  Use the extra balsa to come up with your own design.  There are plenty of options.  Time to be experimental.

There are so many things you can change on your aircraft:

  • Aspect ratio
  • Wing span
  • Wing width
  • Wing shape
  • Fuselage length
  • Elevator size
  • Elevator angle
  • Rudder size

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