Design your flight 2013 guru gobind singh indraprastha university-team leo (2)
In the preliminary design stages, various designs were studied and analysed for
their performance in accordance with the problem statement. Design aspects
which were beneficial for one aspect of flight but harmful for some other were
weighted for pros and cons and an ultimate decision was made in order to come
up with the best possible design for the required problem statement.
The monoplane was selected even though the biplane design offers greater
strength. This was because, strength was not the paramount concern as the plane
was supposed to be light and the preliminary designs which were tested using
ANSYS software confirmed that the structure was strong enough for the
purpose. Further biplanes have inherently more drag for a given amount of lift
than monoplanes. Monoplanes are capable of higher speeds and lower energy
Markets were surveyed for the availability of construction material as well as
the auxiliary items required to build the plane under a decent budget and of the
Out of the various types of batteries available, the Lithium Polymer (Li-Po)
battery was chosen even though it is more expensive. Li-Po batteries offer the
advantages of lower weight and increased capacity and power delivery.
Organization of the team
Various team members were given the responsibility of various aspects of the
project. They were given these responsibilities along with the authority
necessary to carry out their responsibilities. The person best suited for the
department was chosen democratically and according to their abilities. The
members in each department were also chosen according to their abilities and
keeping in mind their personal choice. Figure1 is a diagrammatic representation
of the team’s organization.
The network analysis diagram in figure 2 clearly shows the time taken in days
in order to complete a specific task. Division of work enabled the work to be
completed quickly as members of each department were able to complete their
own tasks in a short period of time as not much man power was required for any
aspect of the project
The problem statement requires us to carry the greatest payload possible over a
specified course. There are various regulations on take-off and flight and some
restrictions on the weight. Therefore, it is imperative to design the aircraft under
such strict conditions. The greater the payload, the more power the airplane
requires which increases the size of the batteries and the motors ultimately
increasing the size of the plane and its weight as well. Therefore, by restricting
the total weight of the airplane there is also an implied restriction on the payload
that can be carried. Better design and manufacture will help us achieve a result
as close to the maximum as possible.
The NACA four-digit wing sections define the profile by
1. First digit describing maximum camber as percentage of the chord.
2. Second digit describing the distance of maximum camber from the airfoil
leading edge in tens of percents of the chord.
3. Last two digits describing maximum thickness of the airfoil as percent of
This formula is for the shape of a NACA 00xx foil, with "xx" being replaced by
the percentage of thickness to chord.
c is the chord length,
x is the position along the chord from 0 to c,
y is the half thickness at a given value of x (centerline to surface), and
t is the maximum thickness as a fraction of the chord (so 100 t gives the last
two digits in the NACA 4-digit denomination).
Various aspects like chord, camber etc. are illustrated in figure (A).
m is the maximum camber (100 m is the first of the four digits),
p is the location of maximum camber (10 p is the second digit in the NACA
Equation 2 was used as the cambered airfoil offers a number of advantages over
the symmetrical one.
1. Ar = Wing span/Chord length
Ar is aspect ratio
2. Wing loading= weight in oz / area in ftsq.
3. Lift=1/2 .rho. v sq.. wing area.coff. of lift
4. Wing planform area= chord length . wingspan( both for upper and lower
• Various components like wings, fuselage etc. were designed using PTC
wildfire 5.0 (Pro/E).
• The design is according to the norms given in the rulebook.
• The initial design was tested for operational validity using ANSYS.
• Calculations for specifications of the driving and control motors were
done using MotoCalc 8.
The usage of software to design and test a prototype eliminates the need to
construct and test the component time and again thus saving a lot of time and
money both of which can be put to better use. But, the usage of the software
does not completely eliminate the need for models.
Several 1:1 scale models were made for solving the following problems.
• Check the availability of space for components like motor, controls etc.
• Check the dimensions achieved in actual practice.
Figure 3 shows the first prototype which was constructed out of thermocol and
glue. As can be seen, it employed a biplane design which was later discarded in
favour of a monoplane design as the monoplane gave a more satisfactory result
Figure 4 shows the final model that was constructed which more closely
resembles the final design of the plane
It was constructed after the monoplane was found out to be more advantageous
as compared to the biplane design as per our requirements.
After a number of designs on computer softwares and the construction of
models, a design was approved; which was deemed to be the final design.
Manufacturing and fabrication of the design was approved by the team with
valid proof that the design in robust and fit to carry out its function.
Figure 5 shows the final design of the wings.
The final wing design has the following specifications;
• Design : NACA 2417 profile
• Material Used: Balsa Wood
• Strength (kPa): 18100 for compression parallel to grain, 4600 for shear
parallel to grain, 1200 or tension perpendicular to grain.
• Justification for selection: Balsa is an ideal material for constructing an
RC plane. This is due to the fact that not only is it light but also has high
strength for its weight. Also, it does not fail easily in bending which is the
type of stress which the wings need to withstand.
Figure 6 CFD analysis of airfoil
Figure 6 shows the successful CFD analysis of the airfoil carried out on
Figure 7 Modal analysis
Figure7 shows the modal analysis of the wing span on ANSYS. Modal analysis
uses the overall mass and stiffness of a structure to find the various periods at
which it will naturally resonate. These periods of vibration are very important to
note in dynamic systems, as it is imperative that the natural frequency does not
match the frequency of expected vibrations. If a structure's natural frequency
matches the frequency of vibration, the structure may continue to resonate and
experience structural damage.
The analysis of the landing gear is important as the landing gear must be able to
withstand the entire weight of the plane while landing. Analysis of the landing
gear in ANSYS reveals that the design is well within the safety required for
Figure 9 shows the isometric view of the assembled plane on PRO/E.
Figures 10 and 11 show front view and top view respectively
Figure 12 Motor Specifications
Figure 12 shows the result for the motors to be used as indicated by the design
software MotoCalc. Using this information the driving and control motors were
selected from the ones available in the market.
Motor: 1800rpm/V; 0.2A no-load; 0.056 Ohms.
Battery: 1800mAh @ 3 cell 11.1V; 0.0257 Ohms/cell.
Speed Control: Generic Brushless ESC; 4 controls (separate); 0.006 Ohms;
Figure 13 shows the controller used for flying the plane. It is a 4 channel
controller. The receiver that is used along with this controller is shown in figure
The Lithium Polymer battery used is shown in figure 15.
Figure 16 shows a micro servo motor. Servo motors are used for control
mechanisms. Their capacities in accordance with the values calculated for a
Once the design was complete and the models were analysed and the team
members were satisfied that the design is up to the mark, the manufacturing
process was started.
The wing airfoil was made of balsa and bonded together in pairs in order to give
greater strength. The manufactured wing is shown in figure 17.
Such intermittent construction allows us to reduce the weight of the wings and
still maintain the shape and strength required for flight. A single airfoil is of the
shape shown in figure 18.
Figure 19 shows the fuselage of the plane. It has been constructed out of
chloroplast and has been bonded using super glue. Super glue was selected after
carefully analyzing the pros and cons of several bonding materials available.
The pros and cons are listed in table 1. Super glue was selected as it was easily
available and was the best option for bonding several components as the entire
airplane is not made of a single substance but is a composite of several
Figure 20 illustrates the push rod mechanism employed to control the motion of
the airplane. Figure 21 shows specifically the aileron control. The links are
fixed in such a way that they coincide with the zero position of the motor when
in the neutral position. This enables the controller to move the controls in either
direction easily and bringing it back to the mean position is a fairly simple task.
A safe and reliable design approach was adapted. Extensive testing has been
done including the gliding capabilities of the models constructed and static
analysis of the model we are ready with the final design and the airplane is
approaching completion. All is left to do is the flight analysis and test the limits
of the airplane so that the plane which we put forth to compete is capable of
competing with the other teams.