Transcript PowerPoint

Guidelines Presentation
Aircraft Aim & Judging
The aircraft needs to transport the mirror segments of
the ESO European Extremely Large Telescope, being
built by OpTIC Glyndwr, in the most economical way.
To judge this, we will look at the flight range with a
given amount of fuel that each aircraft will be able to
achieve using the Engineering Flight Simulator.
Payload
 The aircraft needs to carry 1000 segments of the main
mirror – Each mirror segment is hexagonal and 1.5m
across, and 0.1 m thick, and weighs 15kg each.
 These segments can be arranged in the fuselage how
ever the designers see fit.
Engineering Flight Simulator
The overall concept needs to be planned and draw up
ready for the Simulator, and the concept is based on
whatever the team decides.
The Simulator takes mass, geometric, and
aerodynamic information to predict how the aircraft
will perform and handle.
Fundamentals
For economic flight; drag needs to be low resulting in low
thrust requirements; and weight needs to be low requiring less
lift generated
Aircraft Axis System
3 View G.A. Drawing example
Remember to
draw to scale –
and note on
the drawing
what it is.
Areas for consideration
 Mass
 Wing
 Fuselage
 Tailplane & Fin
 Propulsion
Mass
 Mass must include payload mass, propulsion mass,
and empty weight of the aircraft
 To calculate Empty Mass we can use “effective density”
– Once the overall aircraft has been drawn, use length,
wingspan and height to create a box round the aircraft.
This volume can then be multiplied by “effective
density” to gain a good estimation of the aircraft empty
mass.
 Typical Value of “effective density” = 2.58 kg/m3
Mass – Effective Density
Wing
 Aerofoil Profile shape will be fixed as NACA 23015
 The wing must have sufficient area to generate enough
lift – Typical Wing loading (Lift/Wing area) = 4700
N/m2 where the Lift = Zero Fuel Weight = ((Empty
mass + Payload mass) x 9.81)
 For economic wings, they should be more long and
thin, like a glider, rather than a delta/triangular – this
gives a higher Aspect Ratio.
 Wing sweep aids high speed flight – shouldn’t need
more that 45 degrees – either forward or back!
Aspect Ratio examples
High Aspect Ratio
Low Aspect Ratio
Wing terms and Calculation
Mean Aerodynamic Chord
Dihedral Angle
Dihedral can be added
to give the plane more
wing levelling stability,
so the plane flies in a
straight line without
the Pilot having to
control the plane all
the time. Positive
angle is upwards.
Wing setting angle
Wing setting angle is usually a small angle,
from 0 to 5 degrees – gives good compromise
between take off and the cruise conditions
Main Wing positioning
Place the
Aerodynamic centre
of the main wing
behind the centre of
mass of the aircraft
as this will impart
natural pitch
stability.
Fuselage
 Fuselage layout needs to be an aerodynamic envelope
that surrounds the Payload and the Pilots
 Payload layout is entirely down to the team
Tailplane & Fin
 Size and positions can be calculated from Fin and
Tailplane volumes.
 Volume = Area of surface x Distance of Aerodynamic
Centre from Centre of Gravity
 Researching and working out volumes from existing
aircraft will give typical values. Centres of Gravity can
be estimated by it being 1m forwards of the rear
wheels.
 Aerodynamic Centres of Fin and Tailplane can be
calculated in the same way as for the main wing.
Example Fin Volume
Fin Volume = Tail Arm x Fin Area
Fin & Tailplane examples
Propulsion
 Choice of type of engines – Propeller or Jet propulsion
is a design choice.
 Propeller - Typical BHP/Zero Fuel Weight Ratio =
0.092
 Jet - Typical Thrust/Zero Fuel Weight Ratio = 0.4
 Using Zero Fuel Weight = ((Empty mass + Payload
mass) x 9.81) we can work out Thrust requirement by
multiplying this value by Thrust/Weight Ratio.
 Then choice of size, number and position of engines
can be made.
Controls
Control surfaces deflect to
produce aerodynamic force
which the Pilot uses to
control the flight direction.
Angles can be suggested,
and will be refined during
flight testing.
Aileron Span fraction is the
length of both ailerons
divided by the overall wing
span.
Moment arm is the distance
from the aerodynamic
centre of the aileron to the
plane’s centre of gravity
Be innovative in design
Questions