This document summarizes the design of an aircraft called Team Stratos Micro by a college engineering team for an aeronautics competition. The team aimed to design an aircraft weighing less than 900g that could fit in a box of specific dimensions and be powered by an electric motor. The initial design concept was for a delta wing aircraft with canards for stability. Parametric and fluid simulations as well as structural analysis were conducted to analyze the design. The first flight crashed due to longitudinal stability issues. The design was then reworked with design changes like adding flaps and rudders, and adjusting the center of gravity and canard design based on reanalyzed stability requirements.

1. Team Stratos Micro
SAE Aero East 2012
Team Number : 324
BMS College of Engineering
Bangalore INDIA

2.  We are from BMS College of Engineering from Bangalore, INDIA..
About the Team
NAME YEAR ROLE
Vijay Gopal IV year Design, Simulation
S Darshan II year Design, CAD
Modelling
Linford Pinto III year Material Science
Rahul N III year Fabrication
Haneen Moideen II year Fabrication
Vikram Sharma III year Electronics
Vinay K Hegde IV year Electronics
Honey B Mehta III year Sponsorship
Arvind Kashyap II year Sponsorship
Shadman Alam II year Test Flying

3. Team Stratos Project Flow
The preliminary literature survey
was done in the month of January
2012 while the concept design had
been established by the end of
February following the flow chart

4.  The maximum weight of empty aircraft should be less than 900g.
 The disassembled aircraft should fit into a box of 24X18X8 cubic inch.
 The aircraft should be battery powered and to be propelled by an electric motor.
 The aircraft should be able to carry payload of convenient weight.
 The aircraft should be able to enclose a volume of 2X2X5 cubic inch.
Design constraints

5.  The design was made keeping in mind to have best possible plan area to fit inside a box and to
allow extra structure to fit in if plan area is not adequate to increase the same.
 The team decided to have maximum incomplete delta wing inside the box along with fuselage
in one piece. It was also decided to have a three piece wing in which the center one was
incomplete delta and other two on either sides was elliptical to have minimum vortex effect.
 To ensure longitudinal stability it was decided to have canard with an appropriate nose
 Advantages:
1. Produces large lift while having least number of components to be assembled
2. Has good pitch control because of canards
3. Flow over Canard and Delta is laminar
4. Structurally strong
 Disadvantages:
1. Difficult to construct
2. Very sensitive to changes in CG
3. Difficult to launch by hand because of pusher configuration
Concept Design

6. Concept Design
Isometric view of the aircraft showing internal structures

7. Parametric Analysis
The parametric analysis focus on concept design’s mathematical modeling by treating design
parameters as variables and hence analyzing the required aerodynamic variables keeping in
mind the design constraints along with it.
The parametric analysis was split into 5 areas
• Variable analysis of incomplete Delta wing region with flaps and effects of canard.
• Variable analysis of ellipse wing region with ailerons.
• Variable analysis of fuselage with the help of circulation theory.
• Variable analysis of thrust variation with free stream velocity.
• Stability analysis
• Canard area calculation.
• Position of CG and static margin.
• Vertical Tail area.
All the analysis were obtained through integration of elements level aerodynamic variable such
as Lift, Drag and moment. The aero foil data was converted to convenient linear variation.

8. Numerical Analysis
• Numerical analysis is done based on setting values for design variables which satisfy design
constraints and enter these values into parametric equations obtained from parametric
analysis.
• We assumed an operating velocity of 10m/s
The key things evaluated are :
1. Lift contribution from elliptical section 7N at cruise velocity
2. Lift contribution from incomplete delta section 13 N at cruise velocity
3. For stability, . Stability analysis indicate Canard lift requirement is 1.5N and CG
location of 60cm from nose for a good static margin.
4. Total drag at cruise velocity 10m/s is 6~7 N .
5. The thrust calculated was which is much greater than the drag.

9. Fluid Simulation Results
Pressure distribution for E214 aero
foil at 10m/s at 6 degree inclination
Governing Equations
of fluid
Pressure distribution MH 114 aero foil at 10m/s at
8 degrees inclination with chord length 17inch.

10. Structural Simulation Result
Density
Variation
Von-misses Stress Moment about Y-axis
Governing equation for
beam aligned along x-axis

11. Expected Performance
Approximate linear Thrust
Variation with free stream
velocity for 10X4 propeller with
7000rpm
Mac Lauren series
approximation of
1st two terms gives
Pf = 0.675 – 0.000125*h

12. Crash Investigation
The outline of the crash depicted that the flight had a poor longitudinal stability. The close observation
made that caused this are
•Numerical errors were found in canard area calculation through stability analysis.
•The Centre of gravity of aircraft was not maintained at optimum position as directed by the
numerical analysis due to difficulty in construction.
•The construction of canard was such that the whole canard would rotate about one axis therefore there
was only one common carbon fibre connecting the canard at both the sides. This results in weaker
connection and is subjected to torsion which will affect roll instability.
•The nose that was constructed in such a way that the stagnation was only in the upper part which
induced moment. This theoretical prediction of moment produced by nose was not included in the
numerical analysis.
•The aircraft was flown without payload. The parametric and numerical analysis was done for 1.5Kg aircraft
which corresponds to a payload of 720g as the aircraft weighed 780g.

13. Re-design
Corrections Implemented
•The stagnation properties are made symmetrical in the new fuselage designed. The pressure
distribution is plotted below also the results show less moment contribution from the new rebuilt
fuselage.
New Rebuilt Fuselage Old Fuselage
•The new canard is provided with flaps and two spar is provided which prevents complete torsion
•The aircraft is maintained with uniform aerofoil MH 114 13.02% which is under cambered producing
a max Coefficient of lift of 1.9 and its stall angle is 12*. The aerofoil response is given below.
•The tail is provided with yawing capabilities by providing a rudder to the vertical stabilizer.
•The stability analysis revealed necessary canard area of 62square inches with flap of 35% the
chord length. Also the Cg position is required to be >60cm from the nose for a good static margin.

15. Conclusion
• The design and build of this blended wing with canard model was very
challenging. The team found that nothing could be taken for granted since the
configuration was so sensitive to changes in CG, planform shape, airfoil section
and propulsion.
• Overall, designing and building a tailless aircraft gave us deeper insight into the
design compromises that are a part of aircraft design and construction. We
look forward to demonstrating our ‘unusual’ configuration to the rest of our
competitors.

16. THANK YOU
QUERIES ?