report-10th dec,2015

1

University Of Petroleum And Energy Studies

A Synopsis on

Aerodynamic Analysis of Canard Configured Forward Swept-wing

Aircraft

By:

Shadaab R890213026

Pratham Srivastava R890213020

Thesis Supervisor: Prof. Dr. Sudhir Joshi

Department: Aerospace

Programme: Aerospace Engineering with specializing in Avionics

2

Forward

We would like to express our deep appreciation and thanks to our advisor Prof. Dr. Sudhir

Joshi. His guidance and expert supervision taught us the rightful method of Time

Management to complete the work in time and his vision of approach taught us inventive

apprehension.

He gave us several knowledgeable presentations and brushed up our knowledge about the

various processes and aspects of the phenomenon and the fundamentals of the technologies

less known to us.

October, 2015

Signature of Supervisor Shadaab

Prof. Dr. Sudhir Joshi Pratham Srivastava

3

CONTENTS

PAGE NUMBER

ABBREVIATIONS 4

LIST OF FIGURES 5

LIST OF TABLES 6

LIST OF GRAPHS 7

SUMMARY 8

1 INTRODUCTION 9

1.1 PURPOSE OF THE THESIS 9

1.2 BACKGROUND 10

2 HYPOTHESIS 11

2.1 APPLICATIONS 11

3 METHODLOGY 12

3.1 AIRFOIL SELECTION CRITERIA 12

3.2 AIRFOIL ANALYSIS AND GRAPHS 13

3.2.1 GRAPHS FOR CANARD AIRFOILS 14

3.2.2 GRAPHS FOR ROOT AIRFOILS 15

3.2.3 GRAPHS FOR TIP AIRFOILS 16

3.2.4 GRAPHS COMPARING NET IMPROVEMENT 17

4 CONCLUSION 18

5 REFRENCES 19

4

ABBREVIATIONS

CC-FSW: Canard Configured Forward Swept Wing

FSW: Forward Swept Wing

A/C: Aircraft

Cl: Lift Coefficient

Cm: Coefficient of Moment

Cl(max): Lift Coefficient Maximum

αstall: Stalling Angle of Attack

C.G: Centre of Gravity

5

LIST OF FIGURES

Figure1: Schematic diagram showing canard configured aircraft

Figure2: Schematic diagram showing planar views of a canard configured forward swept

wing aircraft

Figure3: Schematic Figure showing the Reference A/C chosen

6

LIST OF TABLES

Table 1: Table showing airfoils choosen for analysis

Table 2: Table comparing Canard airfoil performaces

Table 3: Table comparing Wing-Root airfoil performaces

Table 4: Table comparing Wing-Tip airfoil performaces

Table 5: Table comparing Reference vs choosen airfoil performaces

7

LIST OF GRAPHS

Graph Set 1: The Graphs showing Cl vs α curve; Cl vs Cd curve; Cm vs α curve; Cl/Cd vs α

curve for the Canard Airfoil


curve for the Wing Root Airfoil


curve for the Wing Tip Airfoil


curve for comparison of the airfoil selected in Reference Aircraft for Root and

Tip of the Wing and the given Project

8

Aerodynamic Analysis of Canard Configured

Forward Swept-wing Aircraft

SUMMARY

CANARD is a secondary wing which is located in front of the main wing. It is used as a

horizontal stabilizer, controlling the longitudinal movement of an A/C. From aerodynamic

point of view canard is added to increase the maximum lift and flow control over a main

wing. For the stability and control ability, canard is often used when the reduction of static

margin and pitch control trimming is required. The canard has the advantage over the tail

mounted stabilizer/elevator in A/C maneuverability, but does not work as well with a flapped

wing.

A FORWARD SWEPT WING is an A/C wing configuration in which the quarter-chord line

of the wing has a forward sweep.

Perceived benefits of a forward-swept wing design include Design Of Dragon Fly A/C.

Mounting the wings further back on the fuselage, allowing for an unobstructed cabin or bomb

bay, as the root of the wing box will be located further aft. Increased maneuverability, due to

airflow from wing tip to wing root preventing a stall of the wing tips and ailerons at high

angle of attack. Instead, stall will rather occur in the region of the wing root on a forward

swept wing. This reversed span wise airflow should reduce wingtip vortices, generating less

drag and allowing a smaller wing.

The aerodynamic characteristics between the canard and wing of the Canard-forward swept

wing A/C configurations have been investigated numerically at low Reynolds number. The

aerodynamic interference and the mutual coupling effect between the canard and wing will

have great influences on the lift, drag, and sideslip characteristics of the whole A/C. The

canard-generated vortex can induce a favorable interference onto the main wing, controlling

the onset of the boundary layer separation from the leading edge.

At small angles of attack (α<10 deg) the aerodynamic characteristics are sensitive to the

relative position of the canard and the wing, but at high angles of attack (α>20 deg) they are

not only related to the orientation of the canard (forward or backward), but also the features

of the vortices generated above the canard and the wing, including their strength and location.

9

1. INTRODUCTION

Figure1

Canard is French for "Duck" which is a wing configuration for fixed wing A/C wherein the

wing on the front is smaller than the wing behind it. It is used as a horizontal stabilizer,

controlling the longitudinal movement of an A/C. From aerodynamic point of view, canard is

added to increase the maximum lift and flow control over a main wing.

A forward-swept wing is an A/C wing configuration in which the quarter-chord line of the

wing has a forward sweep. Typically, the leading edge also sweeps forward. Air flowing over

any swept wing tends to move span wise towards the rearmost end of the wing and on a

forward-swept wing it is inwards towards the root

1.1 Purpose of the Thesis

Key to the advantage of forward wing sweep is the airflow migration inboard as it passes

over the wing. With sweptback wings, airflow moves outboard and to the rear. The

inboard flow of a forward swept wing has the aerodynamic effect of retaining attached

airflow at the outboard sections of the wing even after the wing root has stalled, yielding

greater aileron controllability at slower speeds.

A startlingly prescient encapsulation of the advantages of Forward Swept Wing

technology combined with Canard Configuration enlightened us to conduct a study on the

aerodynamic analysis of one such A/C model with canards under low Reynold’s

Number at varying angle of attacks.

10

1.2 Background

A/C design, more than many other disciplines, exemplifies the phrase “form follows

function.” The laws of physics demand it. Aeronautical designers have always reached

forward, stretching capabilities as far as the constraints of gravity and the limits of

materials would allow their genius to probe. The emerging computer flight control and

composite structures revolutions of the 1970s promised designers access to a hitherto

impossible dream: a canard configured forward swept wing A/C with enhanced

maneuverability and efficiency.

Figure 2

11

2. HYPOTHESIS

Present day efforts in the A/C industry are directed to developing A/C that can operate at very

high or supersonic speeds. Such supersonic A/C, particularly when used as combat fighter

planes, should be highly maneuverable to allow rapid turns, rolls, dives and ascents without

danger of stalling or loss of control.

Recent investigations of A/C configurations indicate that a significant number of benefits

may be achieved by utilizing a forward swept wing (FSW) plan form along with the

implication of canard configuration. When an FSW is used in combination with a canard at

transonic and low supersonic maneuvering flight, favorable interference is provided over the

in-board portion of the wing where the shock is strongest. This leads to higher aerodynamic

efficiency than with the use of aft swept wings [1]

. In addition to providing rapid pitch

control, the influence of canards on wing aerodynamics can often result in increased

maximum lift and decreased trim drag. The reduced or even negative static stability of canard

configurations can lead to improve A/C agility and maneuverability [2]

. On the forward-swept

wing, ailerons remained unstalled at high angles of attack because the air over the forward

swept wing tended to flow inward toward the root of the wing rather than outwards toward

the wing tip as on an aft-swept wing. This provides better airflow over the ailerons and

prevented stalling (loss of lift) at high angles of attack [3]

2.1 Applications

The high maneuverability and negative static stability at high speed flight inculcated

in a canard configured FSW A/C enhance the possibilities of military utilization.

High values of Cl(max) and efficient use of winglets can render a CC-FSW A/C with a

fuel-efficient flight which can be useful in distant target-related operations.

Canards have been applied on supersonic A/Cs to improve the flight characteristics at

low speeds, such as with the Concorde and military fighters

A series of innovative designs has successfully applied canards to improve the

overall A/C flight characteristics , such as with the Piaggio P180, Beechcraft Starship

and Rutan Long-EZ

By controlling the missile with the forward canards, any change of direction will be

direct, whereas control via the rear fins means that the rear end of the missile would

initially move away from the desired direction, until the change in attitude would

move the missile towards its target. Thus, the canard will result in a more agile

missile yet stable

12

3. METHODOLOGY

3.1 Airfoil Selection Criteria

Since we know that in the Forward swept A/C, the airflow direction is from tip to root i.e.

opposite to that of the Conventional sweep back A/C, therefore it is required that the Airfoil

at the root to be stalled earlier than the Airfoil at tip.

A Forward Swept A/C is well-known for its maneuverability and also that in this model,

Elevons are the primary tool for maneuverability, and therefore, it is required to facilitate

conditions to maximize Elevon potential. This, in this case is done by means of canards

which are placed at such a location that their downwash is nullified towards the wing root and

it only has the advantageous effect of the up-wash because of the highly set-back location of

the wing root. Also when considering the Canards, they are placed ahead of the wing since,

they play the crucial role of balancing the moments around C.G.

A basic design of forward swept wing aircraft which was published online[5]

was taken as

reference design, shown below in figure, and considering that design, research on the theory

of stalling wing root earlier than the wing tips by searching for suitable airfoil which can

meet the design requirements along with above mentioned stall characteristics and

appropriate Cl values for the wing was done. For various airfoils, a detailed study about their

various characteristic curves and aerodynamic factors such as L/D Ratio, Cl(max)

Values,αstall, Cm, Cd etc. was done.

Concluding from the airfoil analysis, three airfoils were found which met the basic

maneuvering and aerodynamic characteristics.

Figure 3

13

3.2 Airfoil Analysis and Graphs

On the basis of previously given requirements, the following analysis for various airfoils

including the initial airfoils given by the source Author[6] was done. Here, according to the

Reference A/C design, canard airfoil was kept symmetric and the wing root to tip airfoil was

kept constant.

Now, in this project, unsymmetrical airfoils were studied for canards as well.

Following are the Graphs and Characteristic Curves of various airfoils selected for Canards,

Wing Root, Wing Tip respectively.

CANARD

AIRFOIL

WING ROOT WING TIP

Reference

Aircraft

NACA 0008 S1223 S1223

Experimental Set

1

SD 6062 SD 6060 NACA 4412

Experimental Set

2

MH 24 S8052 NACA 4415

Table 1

14

3.2.1 Graph for Canard Airfoils

Table 2

The airfoil used for canards in the reference A/C clearly stalls before both of the experimental

airfoils taken in this analysis and also gives a comparatively lower value of Cl(max)

Airfoil αstall(degrees)

Canard airfoil(Reference Aircraft) 6

Canard Airfoil(Experimental Set1) 7

Canard Airfoil(Experimental Set2) 8

15

3.2.2 Graph for Wing Root Airfoils

Table 3

The airfoil used for the wing root in the reference A/C clearly stalls before both of the

experimental airfoils taken in this analysis and but gives a comparatively higher value of

Cl(max)


Wing Root airfoil(Reference Aircraft) 7

Wing Root airfoil(Experimental Set1) 11.5

Wing Root airfoil (Experimental Set2) 12

16

3.2.3 Graph for Wing Tip Airfoils

Table 3

The airfoil used for wing tip in the reference A/C clearly stalls before both of the

experimental airfoils taken in this analysis and but gives a comparatively higher value of

Cl(max).


Wing Tip airfoil(Reference Aircraft) 7

Wing Tip airfoil(Experimental Set1) 15

Wing Tip airfoil (Experimental Set2) 16

17

3.2.4 Graph for Final Airfoils[Experimental Set2}

Table 4

On the basis of above analysis between the reference A/C model and the Experimental Sets

of airfoils for the canard, the wing root and the wing tip, we choose the Experimental Set 2

airfoils for the given aerodynamic analysis since, these give optimum stall characteristics

with significant gap between each stalling angle of attack and also provide ample room for

maneuverability.


Canard Airfoil (Reference A/C){NACA 0008} 6

Wing Airfoil(Reference A/C){s1223) 7

Final Canard Airfoil {MH24} 8

Final Wing Root Airfoil {s8052} 12

Final Wing Tip Airfoil {NACA4415} 16

18

4. CONCLUSION

Based on initial analysis and background study test results, forward swept wings with canard

configuration were projected to provide quantified aerodynamic characteristics and

configuration dependent advantages when compared to conventional designs of comparable

weight.

Based on the initial stage study, we observed that the canard configured FSW aircrafts have

following characteristics to be considered in various combat and military applications:-

Reversed span wise airflow should reduce wingtip vortices, generating less drag and

allowing a smaller wing.

A forward-swept wing becomes unstable when the wing root stalls before the tips,

causing a pitch-up moment, exacerbating the stall. This effect is more significant with

a large forward sweep.

Increased maneuverability, due to airflow from wing tip to wing root preventing a

stall of the wing tips and ailerons at high angle of attack.

Airfoils chosen for the wing tip should stall at a high angle of attack and also the gap

between each stalling angle for Wing Root and Canard should be such that Canards

stalls earlier than root for getting high maneuverability, less prone to stall.

When wing flaps are not desired (for simplicity as in ultra-light aircrafts), or

competition rules as with standard class sailplanes, the Clmax of a canard may exceed

that of an aft-tail airplane.

Fuel center of gravity lies farther behind aircraft C.G. than in conventional designs.

Finally, and perhaps most importantly, canard sizing is much more critical than aft tail

sizing. By choosing a canard which is somewhat too big or too small the aircraft

performance can be severely affected. It is easy to make a very bad canard design.

Hence considering various aerodynamics characteristics of CC-FSW Aircrafts, we are further

seeking into exploring the vast possibilities of it with our ever helpful guiding mentor Prof.

Dr. Sudhir Joshi Sir and available resources.

19

5. REFERENCES

[1]: Koenig DG, Aoyagi K, Dudley MR, Schmidt SB. 1988. High performance

forward swept wing aircraft. [accessed 2015 Oct 8]; :1.

https://www.google.com/patents/US4767083

[2]: Eugene L. Tu. "Vortex-wing interaction of a close-coupled canard

configuration", Journal of Aircraft, Vol. 31, No. 2(1994), pp. 314-321.

doi: 10.2514/3.46489.

[3]: Johnsen FA. 2013. The Background of the X-29. In: Sweeping forward :

developing and flight testing the Grumman X-29A forward swept wing research

aircraft. NASA. p. 27–28.

[4]: D.Raymer(1992). Aircraft Design-A conceptual approach. American Institute of

Aeronautics and Astronautics. P. 4. ISBN 0-930403-51-7.

[5]: Rcfoamfighters, P.P. (2009, 06-06-2009). New Project Idea. [Weblog]. Retrieved

5 December 2015, from http://rcfoamfighters.com/blog/?m=200906

https://www.google.com/patents/US4767083

http://rcfoamfighters.com/blog/?m=200906

report-10th dec,2015

Documents