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NUR AIZAT NAZIHAH BINTI AZMI

EXPERIMENTAL STUDY ON WING DEFLECTION OF A HYBRID VTOL UAV

SUPERVISOR : IR. DR.-ING. M. NAZRI M. NASIR

CO-SUPERVISOR : PROF IR. DR. SHUHAIMI MANSOR

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PROBLEM IDENTIFICATION

  • Wing as cantilever beam.
  • During vertical takeoff, weight of wing is acting downwards as distributed force while lift from motors is acting upwards as concentrated force.
  • Wing of a hybrid VTOL does not generate lift during takeoff while wing of a fixed wing UAV does

Lift

Weight of the wing

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SCOPES

OBJECTIVE

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TYPE OF UAV

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Hybrid VTOL

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Same Power Plant for VTOL, Hover and Forward Flight

Separate Power Plant for VTOL, Hover and Forward Flight

Source: Saeed, A. S., Younes, A. B., Cai, C. and Cai, G. (2018) ‘A survey of hybrid Unmanned Aerial Vehicles’, Progress in Aerospace Sciences, 98, pp. 91–105.

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METHODOLOGY

    • Estimate MTOW of UAV
    • Determine new wing dimension by using theoretical calculation and data from existing studies
    • Conducted thrust test to identify thrust available during vertical takeoff
    • Determine wing deflection for fixed wing mode
    • Conducted vibration test to determine the deflection at the tip of the wing

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REFERENCE UAV

Type of Wing

Straight Wing

Airfoil Type

E205

Wingspan

1.2 m

Semi-span

0.6 m

Wing Area

0.294 m2

Aspect Ratio

4.9879

Chord

0.245 m

In this design project, a modification on a rotor fixed wing UAV was carried out.

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1. WEIGHT ESTIMATION

Importance:

  • To find suitable dimension for the new wing, the weight of the needs to be determined first because amount of lift needed to fly a UAV depends on its MTOW

Components/

Parts

Unit

Weight per unit (kg)

Total Weight (kg)

Front VTOL

2

0.180

0.360

Rear VTOL

2

0.180

0.360

Pusher

1

0.180

0.180

Propeller arm

2

0.060

0.120

Servo

2

0.014

0.028

Battery

1

0.450

0.450

Fuselage

1

0.800

0.800

Wing (and spar)

2

0.500

1.000

Flight controller

1

0.046

0.046

ESC

1

0.097

0.097

Telemetry

1

0.021

0.021

GPS module

1

0.033

0.033

Receiver

1

0.034

0.034

TOTAL WEIGHT (kg)

3.52

Result:

MTOW = ±3.5kg

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2. WING DIMENSION

The wing area data collected from existing VTOL had lower values from the calculated values. It was decided that the best method to adopt for this investigation was by referring to wing area calculated from lift equation.

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3. FABRICATION OF MODEL WING SPAR

There were significant difference between flexural strength of an EPS foam and a pure aluminium. This value was relatively small that EPS foam could be considered to have zero contribution on supporting forces acting on the wing.

Material

Flexural Strength (Mpa)

Source

Aluminium

80

Krishnaiah, A., Chakkingal, U. and Kim, H. S. (2008) ‘Mechanical properties of commercially pure aluminium subjected to repetitive bending and straightening process’, Transactions of the Indian Institute of Metals, 61(2–3), pp. 165–167.

EPS Foam

0.088

Beju, Y. Z. and Mandal, J. N. (2017) ‘Expanded Polystyrene (EPS) Geofoam: Preliminary Characteristic Evaluation’, Procedia Engineering. The Author(s), 189(May), pp. 239–246.

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4. CALIBRATION OF THRUST STAND

Importance:

  • To ensure the reliability of thrust stand in producing accurate thrust measurement

Thrust Stand

Dynamometer Series1520

Weights

500g – 3000g

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Load (N)

Mean

Std. Dev

0

-0.00012

0.003389

4.932

4.935828

0.001984

9.826

9.827434

0.003772

14.739

14.73609

0.003133

19.623

19.63363

0.004683

24.536

24.5369

0.003395

29.468

29.4744

0.004758

 

RESULT

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5. THRUST TEST

Objectives:

  • To determine amount of thrust and power available
  • To verify the suitability of the motor used in providing lift during vertical takeoff

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RESULT

 

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Throttle (%)

Thrust (N)

Current (A)

AVE

20-29

0.0431449

0.8560183

30-39

2.1673667

11.168758

40-49

5.0138764

26.42578

50-59

8.4747104

47.11842

60-69

12.737883

72.267097

70-79

17.898299

103.56589

80-89

23.869943

140.3111

90-100

30.689444

182.73193

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6. VIBRATION TEST

Objectives:

  • To find out the deflection at the tip of the wing in z-direction

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RESULT

The result showed that hybrid VTOL experienced a larger deflection at wing tip than a fixed wing. Factors that contributed to this finding were the concentrated upward lift force and also fluctuated force coming from vibration of the motor driven propeller.

Isometric view

Front view

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RECOMMENDATIONS

  • Improve the presented method to study the wing deflection of a rotor fixed wing
    1. Use a complete wing rather than only wing spars.
    2. Conduct flight test to verify data collected from ground vibration test.
    3. Carry out wind tunnel testing for model wing for more accurate result rather than using only theoretical calculation.

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CONCLUSION

  1. Manage to achieve objectives set at the beginning of the study on this subject.
  2. Research question have been answered.

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THANK YOU