Aerodynamic characteristics of the lateral control device (spoiler) of the MU-2 utility plane

25 SEP 1972

PRC1

Aerodynamic Characteristics of the L

Device (Spoiler) of the MU-2 Utility

o

a-Introduction

The MU-2 which has recently been awarded a Type Certificate by the Japan Civil Aviation Bureau is a utility

plane having various features as STOL plane. one of

which is a spoiler adopted in place of a conventional aileron.

A spoiler is a device which controls aerodynamic forces

acting on a wing by forming a separated flow on the upper surlace of the wing and thus by substantially de-forming the wing section. It is _{nowadays adopted for}

many airplanes as a lateral control device, as a subsidiary means of lateral control or as a drag plate and

simul-taneously as a lift alleviation device at the time of landing.

though it has so far been used as a drag plate for airplane

or glider. However, there has been no airplane of manual

control whose lateral control depends on the spoiler only

except for tile MU-2 because of its several serious defects

concealed under its charming features. In this respect, the MU-2 is the first airplane in the world which has adopted the spoiler as a sole means of (manual) lateral

control.

In this paper, various kinds of spoilers so far develop-ed are reviewdevelop-ed and analyzdevelop-ed. Next, the results of our research on the Mitsubishi spoiler which has been first

adopted for tile MU-2 are described. And finally, its

aerodynamic characteristics are explained based on

wind-tunnel and flight test data.

Spoilers Developed So Far

2. 1 Their merits and defects

The spoilers so far developed have various attractive

merits as follows

Such powerful high lift devices as full-span flaps can

be used.

Such phenomenon as aileron reversal can be relieved. (good high-speed control effectiveness)

They are usually accompanied by favorable yawing

Bibliotheek van d

Lab. vi. Scheepsbouwkunde

Technische Hogeschool

Ift

Aa{dein

ni&e -ioaeschoo DOCUMEN AIlE DATUM: epsbouwkunde 12 U(1. 1912

Sitigetushi

'l'akata", Yoshio

asakt,

Minoru Ikai* and Kazuo Arashi*

Abstract

The zeroclvnwizc characteristics ?f spoilers in general have first been inti-oduced, and the pi-ogi-ess of research car,-ied out to suì-,nount complicated problems upon bringing tlieiìi _{into practical use for the AlU-2}

Utility l'lane and the results thereof have been uulined. _{Finally, the aerodynamic characteristics of the} .fLJ-2 Spoiler ai-e explained based on wind-tunnel and flight test data.

moment. (favorable for turning)

They llave })etter effectiveness under high lift (flaps

down) conditions in general.

If both right and luft s1)oilers are deflected at the same

time after touchdown UOfl landing, a ground run

dis-tltflce can be shortened clue to increased drag and

decreased lift followed by iii creased brake effectiveness.

Meanwhile, such serious defects as listed below have

remained unsolved:

Poor effectiveness at small cleflections

I'oor hinge moment charact eristics _{(ncnil inearity.}

re-versed or opening hinge moment at small deflections,

etc.)

Time lag in effectiveness

Since spoiler operation is _{usually accompanied by}

unsteady separated flow, it may induce vibration and

bring about structural problems.

Since spoilers are followed by large wakes,

considera-tion must be given to their interference with tailplanes, etc.

2. 2 Illustrations

Although spoilers have many defects as mentioned

above, their merits are so attractive that they have recently been adopted for many airplanes, their defects being cured

or covered by various means anyhow. A list of airplanes

with spoilers is shown in Table 1. and their representative

illustrations are shown in Fig. 1. Those spoilers are used as

Supplementary device of lateral control (for both

large and small airplanes)

Both aerodynamic brake and lift alleviation device

which increases landing gear brake effectiveness (for

large airplanes)

Lateral control device (for power-controlled ship planes)

And spoilers as adopted for large airplanes are usually used as (1) and also (2).

Nagoya Aircraft Works

49

T Ali

140

(a) Boeing 727

SPolie,

Note : All numerical values are approximate mean values.

In cases where the spoilers are used as supplementary device of lateral control, their poor effectiveness at small

deflections. time lag in effectiveness, etc. raise up no

problem, because those defects are covered by the

conventional ailerons. Also, their poor hinge moment characteristics raise up no problem for power-controlled

airplanes.

However, even in case of supplementary use, for such airplanes of manual control as North American 0V-lOA (COIN) and Convair 48 Charger (COIN), circular-arc

type spoilers whose hinge moment is comparatively small

are used; and for such airplanes as Grumman FIIF-1F

Super Tiger. North American A-5A Vigilante and General Dynamics/Grumman F-111, whose lateral control depends

on power-controlled spoilers oniy, ample ventilation is

20'

Inboard and central (b) No,lh American A-5A (Vigilantt)

Fig. 1. An illustration of spoilers as adopted for airplanes

Circular-arc spoiler

(t) Camait COIN (Model 48 Charger)

introduced for the improvement of effectiveness at small

deflections and time lag in effectiveness.

2. 3 Research and development carried out so far

So-called spoilers are considered to be divided into three constituent elements from the aerodynamic point of view:

Spoiler _{Device allocated on the upper surface}

of the wing

Deflector Device allocated on the lower surface of the wing

Slot _{Ventilation gap leading the air flow from}

the lower (upper) surface to the upper

(lower) surface through the wing There are a great many configurations for each device as

well as combinations thereof, which have been investigated. developed and improved through wind-tunnel test and/or

Table 1. List of airplanes

No Airplane Purpose of spoilers

with spoiler

Spoiler

Remarks

hinge

Type Chord ratio Span ratio _position

i Boeing 707 _{and air brakes}Subsidiary lateral control Slot-lip type l5,C 30% 65n/C

2 Boeing 727 3 Boeing C-135 1F, 15 35

30

-65 70 4 Convair 850 10 25 70 5 Convair 990 15 30 70 6 Douglas OC-8 ! 25 75

7 Vickers Super VC-lo Subsidiary lateral control Hinged-flap type 12 30 62

8 Transall C-160 ₂₅

9 BAC 111 Subsidiary lateral contr1_{and air brakes} 13 28 62

10 Canaclair CL 44

815

70

11 Belfast SC 531 I Subsidiary lateral control

9 20 70

12 Hamburger 11FB-314 Slot-lip type 8 20 70

13 Short Britanic Hinged-flap type 9 20 70

14 Grumman/F11F-1F Super Tiger Lateral control Slot-lip type 14 63 71 (Power control)

15 Grumman A-6A Intruder _{C " )}

16 North American A-5A Vigilante Spoiler-deflector type )_

17 General Dynamics/Grumman F-111

(Manual control)

18 North American 0V-lOA (COIN) Subsidiary lateral control Circular-arc type 30 60

5Spoiler position

19 Convair 48 Charger (COIN) 10 30 50 C )

20 Mitsubishi MU-2 Lateral control Hinged-flap type 55 60 62 C " )

No. Type

1 Plain aileron

2 Hinged flap type_spoiler 3 Retractable spoiler

4 Paddle spoiler

5 I)ellector

6 Retractable

deflector

Spoilet and slot Slot-lip npoi!e-r or slot-lip aileron

9 Plug type spoiler Deflector and slot

Slot-closing deflector Spoiler and deflector wLh slot Rear vow Def lector Deflector Spoiler-slot combination Configuration

c1

Fig. 2. An illustration of typical spoilers

flight test. _{Out of those, typical ones selected from}

References (1), (2) and (3) are shown in Fig. 2. No. i of Fig. 2 is so-called aileron, but it is listed for

reference since it is a kind of lateral control device usable together with full-span flaps. Picking up fundamental ones

out of those, their aerodynamic characteristics would be

explained below. Those which have not been picked up here are nothing but a mere rmodification or a

combina-tion of fundamental spoilers, whose characteristics would easily be surmised from fundamental ones.

Plain aileron (Fig. 3)

This is not a spoiler, but is picked up first to give

the basis for comparison. It is experimentally confirmed

that effectiveness and hinge moment characteristics of plain aileron are smooth, and there is little or no time

lag in effectiveness. However, if it is used as drooped

aileron, its èffectiveness duriitg flaps down would be

poor.

Hinged flap type spoiler (Fig. 4)

TECHNICAL REVIEW. May 1966

Classification Aileron Spoiler Spoiler Spoiler Spoiler-slot combination Spoiler-slot combination

Spoiler and - Spoiler-deflector

deflector i combination Spoiler- slot-def lector combination 0.04 t-) 0.02 O 0.04 La 0.02 Q2 O 10 20 Flap _°1 30'

Aileron deflection angle dog

O

Wing section Clark Y-15

Flap : 20% Split flap

Reynolds number 2x 10

10 20

Flap 60'I

( La0isec)

Fig. 3. Aerodynamic characteristics o aileron

f Wing section : NACA 23012

Flap 26 Slotted flap Reynolds number 2x106

30

C! Rolling moment coefficient HM: Hinge moment (in-lb)

Lift coefficient ó'f :Flap angle Flap 0'

4

flap 401 4

ILagisec

I: 020 w 1.73 025 o 2.40

-o 091 000 1.39 0.00 1.87 0.00 0 2 4 6 8 0 2 4 S Spader projection %

Fig. 4. Aerodynamic characteristics of hinged flap type spoiler

The effectiveness at small deflections of this spoiler is very poor during flaps up and also down, and there

is a hump in its hinge moment characteristics at medium

deflections. It has fairly large time lag in effectiveness.

However, the effectiveness at large deflections is fairly

51

cuIIII/7Li..

_Ti

Deflector-slot

ble to close s I combination

CL La01 see 0 00 0.00 0.36* o 1.02 12 8 4 O 4

Wing section: NACA 2,3012 Flap :26% Slotted flap Reynolds number:2 X 10

um

muUdi

um

uumiui

Flap Q" Flup 40 ..._55% 6 8 0 2 Spoiler projection n6

Fig. 5. Aerodynamic characteristics ot retractable spoiler

Wing section: Clark Y-15

Flap: 2Q'2 Split flap Reynolds number: 2x 10

Wing section: Clark Y-15 Flap : 20 ?6 Split flap Reynolds number: 2 x 10

Wing section: NACA 23012

Wing section Clark Y-15

Flap: 20% Split flap

Reynolds nomber:2 xlO°

Fig. 6. Aerodynamic characteristics of deflector

spoiler as mentioned in (2). Deflector (Fig. 6)

Some deflectors llave good effectiveness at small de-flections under high lift conditions, but its effectiveness is small in general and reversed under certain conditions.

Its hinge moment characteristics at small deflections

are irregular. Time lag in effectiveness is, however, comparatively small.

As the deflector is a device which produces a negative

lift by making tile separated flow reattach _{on the lower} surface of the wing under favorable pressure gradient,

it _{is a little different from the spoiler which decreases}

a positive lift by making the flow separate from the up. per surface of the wing under adverse pressure gradient.

The characteri.tics mentioned above would be

un-derstood from this different way of flow utilization.

Spoiler-slot combination (Ventilation effect) (Fig. 7) Compared with that without slot, the effectiveness at

small as well as large deflections is considerably improv.

ed because the separation is promoted by high _pressure air led from under the wing up to the rear of spoiler. There being always a slot openingon the lower surface

of the wing, however, it is defect for this type that

drag is _{higher during cruise and hinge moment is}

reversed or opening at small deflections. Time lag in effectiveness is considerably small compared with that

without slot. _{Same spoilers with and without slot} ocre

compared in Fig. 7, from which powerful effect of slot

would be understood. Flap :26% Reynolds Slotted flap number: 2x10t 50 10%

---- ir

(-i D 108 oT4l

[1ap O'] [Ï'ap _°'I

l.pp4i

(' C, agse D11I 0 09 0 36 _o.ot

IIioc8

--

a

Lagec . .qLagsec, ,./'

It.'

0.36 008 io . Oto o ItJ Ö.ot Flap O' Flap 60' agluec ag(sec o 0.36 0.16 - 0.91 024

Lí1kIiII

52 _{1 Iitc,thishi ¡feaz'v Indu.ctries, Ltd.}

O 4 6 8 0 2 4 6 8 Spoiler projection % 4 6 8 0 2 4 6 8 Spoiler pro1ection % 0 2 .4 6 8 0 2 4 6 8 Spoiler projection %

Fig. 7. Aerodynamic characteristics of flap type spoiler-slot combination

(one without slot is also shovnfor comparison)

good, arid the time lag in effectiveness can considerably

be improved by shifting its chordwise location towards tile trailing edge of the wing.

(3) Retractable spoiler (Fig. 5)

The hinge moment of this spoiler is small and its

characteristics are fairly good. Its effectiveness and

time lag are almost similar to those of hinged flaptype

142 0.06 0.04 0.02 o 0.04 0.02 o 0.04 0.02 O 8 4 O 0.04 ç) 0.02 o 0.04 0.02 o

i lavitig fully analyzed tiic characteristics of various

spoilers as listed inn Fig. 2. the lollowing conclusions are

derived

Li) (knerirliv tine upper surtace spoiler alune is insufficient for lateral control because of poor effectiveness at small deflections and large time lag in effectiveness. However,

it may possibly become acceptable if it is shifted after-wards close to the trailing edge. In addition, it is not suitable fur an airplanie of manual'control because of

its irregnillir hinge moment characteristics.

The lower surface deflector alone is inferior to the spoiler in effectiveness at large delections, but superior in both effectiveness at small delfiections and time lag

in effectiveness. If combined with the upper surface spoiler, it contributes to the improvement of

effective-liess at small cleflections and time lag in effectiveness.

If the slot leading the airflow from the lower surface to the upper surface through the wing is added, both cf fectiveness and time lag are improved considerably. However. there is neither spoiler nor deflector with slot yet, whose hinge moment characteristics are factory. Although a plug type spoiler has fairly

satis-factory aerodynamic characteristics, it brings about

structural and vibrational problems.

Zr Project on Deflection6 angle) .. \ 1 8 nj 8 I I Neutral

\

f

\

/-'.\

¿J

\

; 'S

i'

'r nt 'I_il 'III: 0 7 Trailing edge of spoiler _{ioó % 60% 66% 66% 60%} I 72% 65 0u 83%' Leading edge I I 50 % 50 % 23 % 23 % 0.08 0.06 3.Q4 0.02

Fig. 8. Comparison of effectiveness of various spoilers

08 0.6 T

PP

I'

i'

Trailing edge P P P P P P

_{of spoiler}

®

100 % 30 % 60 % 66 % 60 96 60 96 70 to Leading edge _{50% 50°6 23% 23°6}

of deflectoJ

Q CL> 1.5 / Lag J 143 Flap up (.'c< 1.5 Ci >,1,5 --0-- --m-- Flap down Projection t

_{/ .,}

¿,

'

_i V / I i ---

'. z.---

--s» Neutral

tr

\

I'

/

'r j! t

j

Flap down 0 C<1S Ci>1,5 0.06 0.04 u 0.02

Large projection _{o Ci_0.Ï}

Projection Detlection n Ci >0.5 angle 5/' ' / / -¿S Small projection 5/

'i,

L. V ,'ò

Fig. 9. Comparison of hinge moment characteristics

of various spoilers Fig. IO. Comparison of time lag of various spoilers

TECHNICAL REVIEW. May 1966

₅₃

lined to 50 deg.

Detector argle is Spoiler-detlec tor combination I 16 g

'or

7' n 1.0 LElas door! _o Flap up ('t<O 5 l'i >o.5

S po ile r-Id e f lec to r

combina tionLt J QL 0.2 O t 4 o

14.1

(4 lhcrc lias been no satisfactory spoiler especially

suit-al e lo r in anual lateral coi i t ri >1. 1 lowever, since each

type lias each preferable characteristics, it is expected tu develop a spoiler sufficient for practical use by further

research and improvement.

As a guide

to further

research and development, effectiveness, hinge moment and time lag of various spoilers are systematically shown

in Figs. S through 10.

3. Research of Spoilers in Our Company

:1. 1 Flow around spoiler

As mentioned previously spoilers with so many merits

are very attractive for lateral control, but further

improve-ment of their defects (poor effectiveness at small deflec-tions, nonlinearity of hinge moment, time lag in effec-tiveness, etc.) is necessary for practical use. Especially,

to adopt spoilers for the MU-2, the problem becomes more difficult because of manual control. To solve this, analyti-cal investigation and research must be carried out, studying

the flow around spoiler in detail.

Little has hitherto been done on investigation into the

flow around spoiler, and probably because of complexity

and knottiness of spoiler wake, those who have treated it theoretically seem to be merely Woods'41 and Omori. However, they have rnucroscopically grasped the overall

characteristics under bold assumptions, avoiding to touch

Spoiler deflection angle

3O

on the detail of wake. Therefore, it is impossible to

expect the improvemnent of effectiveness at small

deflec-tions and hinge moment characteristics in question from

these theories.

In Fig. 11 is shown a part of test results on the flow

around two-dimensional spoiler carried out in Small

Wind-Tunnel (20 lIP, test section =-06 m high. 0.08 mn

wide, 1.1 m Ion g)of Aerodynamic Research Section, Nagoya

Aircraft Works.

When the spoiler is operated, the wake is formed behind

it and the dividing streamline (a free streamline flowing out of the trailing edge of the spoiler) goes along its free

boundary. As a result, the profile of the wing is

effec-tively deformed, the flow around the wing is changed and the pressure distribution is changed. Moreover, the spoiler

wake is relatively large compared with spoiler projection and thus it is expected that a comparatively small amount

of spoiler projection would have considerable effect. Tufts in front of the leading edge of the wing in Fig.

11 show

that according to the growth of the wake

accompanying the spoiler operation, the flow direction

/ Spu.ir

a Wind direction

<i

This part is enlarged

and shown above.

54

_{itJ'jts,bis/,j heavy Industries, Ltd.}

Fig. 11. Change of flow pattern clue to spoiler

-0.4

24

08

Fig. 13. rasic nuslel of wing with spoiler

o Experime Theory

i

nt 75 o 20 40 60 80 1/C n Omori 1i/c 2.4 % o Experiment Theory

oo

100 0 20

Fig. 14. Load distribution due to spoiler

against the leading edge of the wing is gradually bent

downwards, i.e., the stagmltlon point is shifted upwards. This means that the lift of the wing is gradually decreased

due to the spoiler operation.

Upon seeing the above, it is understood that the spoiler flow is fairly clean and regular if the spoiler is located near the trailing edge of the wing. In reality, it is quite

a neat flow in the region outside the wake, and good results have been obtained by applying a potential flow

theoretically.

Elle problem is the wake part. The nature of wake behind the spoiler is _{considerably affected not only by}

spoiler deflections, but also by Reynolds number, pressure gradient, ventilation, etc. An example of the wake is as

shown in Fig. 12, which is also a part of flow test results on two-dimensional spoiler in the aforementioned Small Wind-Tunnel. As is seen from these photographs. the wake is a subtle thing: the boundary which forms the wake region is vague and there is no distinct dividing streamline if looked at in detail, and the flow within the wake is also a troublesome thing consisting of large and

small vortices accompanied by a disturbed wake.

Now, if the detailed investigation of the wake is once put _{aside, it is sufficient to consider basically a flat-plate} wing with normal spoiler at zero angle of attack (Fig. 13) as a theoretical model of a wing with spoiler, as is treated in the previous two theories. A load on the flat-plate wing at zero angle of attack is of course zero, and

the load distribution on that with normal spoiler Jc1,

(pressure difference between the upper and lower sur-faces) becomes as shown in Fig. 14.

On the upper surface of tile wing, there act a down. ward force before the spoiler due to a pressure rise, the

flow being dammed up by the spoiler, and an upward force

behind the spoiler clue to a low pressure of the wake.

Therefore, three components Cr, Ci, C,, produced by such a load distribution are largely varied by a chordwise

loca-tion .r,/c and an amount of projecloca-tion /i,/c of the spoiler. A lift variation Je versus chordwise spoiler location is shown in Fig. 15 (References (4) and (5)).

TEChNICAL REVIEW. May 1966

,.r _. -tLlr-65 o 40 60 80 100 n/C % Woods 40/C= 2.0 ' 1.0 0 8 0.6 0.4 0.2 o 0.2 20 40 60 80

Spoiler chordwise positron x. /C o

100

Fig. 15. Effect of chordwise spoiler location on lift drop

145

A lift decrement JCr due to the spoiler is larger when

the spoiler is closer to the trailing edge, especially the

effectiveness at small deflections is improved considerably.

This kind of phenomenon is generally true, although it does not necessarily coincide with Fig. 15 according to

Reynolds number. airfoil section. flaps. angle of attack, kind of spoiler, etc.

There being a pressure gradient on the wing at angle

(if attack, spoiler characteristics are greatly affected by that. Since the spoiler is by naturea device which makes

the flow separate under an adverse pressure gradient, it

may produce an adverse effect under a favorable pressure

gradient. the flow being reattached. This makes the

effectiveness at small dellections poor arid hinge moment characteristics irregular.

The spoiler hinge moment being really affected by the back pressure produced by the wake, the problem cannot

be solved without proper control of this complicated wake, however complicated it may be, being affected by Reynolds

number, pressure gradient and boundary layer of the

wing, configuration and amount of deflection of the

spoiler, etc. It is because this complicated wake could be controlled successfully that good hinge moment

char-acteristics have been obtained for Mitsubishi spoiler.

Next and at last comes the problem ut time lag in

effectiveness: it would take time to form a steady

separa-ted flow after spoiler operation, which turns out to be a

time lag in effectiveness. Though the time lag as shown in Fig. lo beforehand has been defined as time for the

effectiveness to reach of its steady value after stepwise

operation of the spoiler, it is more rational to divide the overall time lag into lag and sluggishness as shown in Fig. 16 for further detailed investigation.

Lag is construed to be a time for the spoiler wake separated region) to reach the trailing edge oh the wing

and sluggishness to be a time for the wake to further settle in its steady form. Therefore, the narrower the wing chord

length is, the closer to the trailing edge the spoiler is

brought, and the faster the general flow velocity becomes,

the smaller the overall time lag would be. h would thus be understood from tile progressive formation of the separated flow that the lag approaches to zero as the spoiler approaches to the trailing edge (Fig. 17), but the

sluggishness decreases slowly and remains finite even in

55

A Eyperiment Theory Ii.,/c 2 8', Omori o E w

A

-Woods g A A A

o.

i 16

56

lo

Time sec

Wind tunnel test results of ototlip spoiler

Fig. 18. _{Elfect of chordwise spoiler location of} sluggishness

3

the case of thc trailing edge spoiler (Fig. 18).

3. 2 _{Improvement research}

Upon adopting the spoiler for the MU-2 as lateral

control device of manual control, the most suitable one,

from the structural point of view, would be of hinged-flap

type (® of Fig. 2 or ® of Fig. 8).

To improve poor effectiveness at small deflections, nonlinearity of hinge

moment, time lag in effectiveness, etc. of this type spoiler. the research has been carried out aiming _{at the following}

points

(1) Increase of effectiveness at small deflections

Since ventilation of spoiler accelerates the formation

of separatci flow, a gap should be formed between

the kading edge of spoiler and the wing surface _and high pressure air below flap should be _{led up to the} lower face of the spoiler. Considerable effect can he expected from these measures _{as is seen from}

compar-L E e 006 L 0.01 o 0.04 0.02 10

C-Wind tunnel lnr.t results of refrdctahle spoiler

n O 0' I=36rr/sec C=l22m

n a=15' V=18m/sec e=l 22m

20 40 60 80

Spoiler chordwise position x,¡C %

100

Wind tunnel test resulto of half wir6 with circular arc type spoiler j Spoiler deflection angle : 3u15'

Spoiler dntlectionr time tsO.O16 sec

0.0

o

X

Slut open Slot sealed

ison of ® and ® or © and ® of Fig. 8.

Improvement of time lag in effectiveness

This is a phenomenon accompanying the increase _of effectiveness at small deflections as is seen from com-parison of ® and ® of Fig. 10 and results of Figs. 19

and

Improvement of hinge moment characteristics As mentioned in 3. 1. "Flow around spoiler", it is

neces-sary to control the spoiler wake, aiud in this case, the improvement of hinge moment characteristics should he

done by a special spoiler cross section combined with the above-mentionci ventilation.

Along this line, a vast research has been carried out for a long period, using 2 m Wind-Tunnel and Small

Wind-Tunnel of Aerodynamic Research Section, Nagoya

Aircraft Works. Flow photographs previously shown in Figs. 11 and 12 are part of it.

[tuit,cubis/zi Ile avy Industries. Ltd.

. .-..,.-Flap O'j Ci.=0 ,.=0.78/Ci=1.09 pp0o_o_.o

:'

Flap _°i

jCi

=200 CL =2 38 ¡"Ci=2

Fig. 16. Time lag of spoiler Fig. 17. Effect of chordwise si,oiler location on lag

0 0,1 0.2 0 0.1 0.2 0 0.1 0.2 0.1 0.2 0.3

Cc Lift coefficient

Time sec

Fig. 20. Time lag of spoiler and its improvement _{Fig. 19. Time lag of spoiler and its improvement}

by means of ventilation (2) _{by means of ventilation (1)}

loo

20 40 60 80

Angle of attack = r a _4' a 8' a-t' t' 't 't 34-94'6/2 (MU?A) 315-96%b12 (MU.2B)

Note : (1) Ci : 2-dim, lift coefficient

Cs 2-dim, hinge moment coefficient

Cs is calculated based on the same reference area and length as those for C,/C=- 10íí.

Fig. 21. Effect of chord length of two-dimensional spoilers

f12

Fig. 22. Spoiler of MU-2

4. Aerodynamic Characteristics of the

Spoiler Adopted for the MU-2

As a result, of the above-mentioned research, the char-tcteristics have been improved enough for practical use

for the MU-2, combining a proper spoiler chord length, a gap between the leading edge of spoiler and [the wing, a ventilation from under the wing up to the lower face of

the spoiler during flaps down, a special spoiler cross

section, etc. A few examples thereof would he mentioned

below.

4. 1 Balance between effectiveness and hinge moment (control force)

Since the MU-2 is of manual control, it becomes first essential for the effectiveness and the hinge moment to satisfy the respective required conditions and to keep

balance. According to two-dimensional spoiler test in the

2m Wind-Tunnel, with decreasing spoiler chord length, the effectiveness decreases only a little, but the hinge moment decreases sharply. As result, it would be

under-TECHNICAL REVIEW . May 1966

Spoiler deflection angle 2.= 20'

-i

0.8 0.6 I 0.4 0.2 0 10 20 30 60 2 deg

Fig. 23 (a). Effect of gap and ventilation on two-dimensional spoiler effectiveness

(without gap and ventilation)

08

0,6

0.4

02

Fig. 23 (b). _{Effect of gap and ventilation on} two-dimensional spoiler effectiveness

(with gap and without ventilation)

r

r.-r

r

40 Flap 0' a,/c=O 9f -' /r= 10% Ga/c= 3% Angle of attack 0=4' a = Q' a = 8' 50 Angleof attack 0=8' a = 4' a = 0'

Fig. 23 (e). Ef feet of gap and ventilation on two-dimensionttl spoiler effectiveness

(without gap and with ventilation)

stood that the effectiveness per hinge moment increases rapidly with decreasing spoiler chord ratio as shown in Fig. 21.

Based on these results, spoiler span and chord length as shown in Fig. 22 have been adopted for the MU-2. Although such value as 5.5 for the spoiler chord ratio

57

147 4 10 12 13 10 20 30 40 50 60 ô deg 60 50 10 20 30 40 Os deg 0.8 06 - 0.4 0.2

148 u 01 0.08 0 46 0 0 0.02 0.6 0.4 0,2 Flap 55' = 60

Fig. 24 (a). Effect of ventilation on spoiler characteristics

(without ventilation)

is so small that there is no similar case elsewhere, this

spoiler satisfies pb/2V=0.07 which is generally referred

to as a standard of effectiveness on the one hand and the control force is within the specification of the Avia-tion Agency (60 lbs) > on the other hand.

4. 2 Effectiveness at small defiections and hinge moment characteristics

Out of tile results of the above-mentioned two-dimension-al wind-tunnel test, effects of the leading edge gap and the

ventilation from under the wing on the effectiveness at small deflections are shown in Fig. 23. As is clear from

comparison of (a) and (b), (a) and (c) of Fig. 23. both gap and ventilation llave remarkable effect on the

effec-tiveness at small deflections. However, from the viewpoint

of variation due to angle of attack and linearity, the gap

is superior a bit.

In addition, since the ventilation opening on the lower

surface of the wing causes useless drag even in cases

where the spoiler is _{not operated, the gap has been}

adopted for tile MU-2. Then, the research on the spoiler cross section to control the spoiler wake has succeeded

in removing tuìe hump previously seen in the hinge

moment characteristics and made manual control possible.

After the spoiler cross section has been determined, tests on half-wing tnodel with spoilers of various leading edge

gap widthsnd) have been made to determine the optimum gap width.

In the case of hinged flap type spoiler, both effective-ness and hinge nìoinent characteristics become very poor during flaps down as shown in Fig. 4. To improve these

characteristics, tite utilization of ventilation from under the extended flaps has been taken into consideration, and

tests on ventilation effect have been made with the above

u 0.10 0.00 0.06 0.04 0.02 o Flap 40' 61+ =60% C,/c7% G,/c=1%

Fig. 24 (b). Eulect of ventilation on spoiler characteristics

(with ventilation)

half-wing modelt lo) (Fig. 24).

Remarks : Since full-span double slotted flaps are used for the MU-2, it is structurally quite feasible to feed the high pressure air under the

wing through between the lip and skirt at the rear of the main

wing up to the lower face of the spoiler during flaps down.

From Fig. 21. it is seen that the ventilation effect is quite remarkable. Not only effectiveness at small deflec-tions has been much improved but also linearity of hinge

moment characteristics has been fairly improved.

Mean-while, reversed or opening hinge moment characteristics at small deflections have yet remained as probletn, but this has been solved by a special device in control

me-chan ism

-4. 3 Overall characteristics

The final characteristics of the spoiler thus developed and composed of the optimum combination of gap,

ven-tilation and special cross section are shown in Figs. 25, 26 and 27u1). These are all characteristics of full SCale

airplane estimated from wind tunnel test resultson hail-wing model with necessary corrections being added. Both

effectiveness (Fig. 25) and hinge moment characteristics

(Fig. 26) _{are improved remarkably compared with the} previous ones, and yawing moment due te) spoiler operation

(Fig. 27) is favorable irrespective of flap positions in the normal range of angle of attack and is neutral or weak adverse in the vicinity of stall.

The effectiveness and hinge moment characteristics obtained from flight tests are shown in Figs.

and 29 14) It is confirnìed that the effectiveness at small

58

_{1Íitsubis/, i IIe'az'y Industries, Ltd.}

10 20 30 40 4 deg 50 60 10 20 30 5 deg 40 50 6

10 20 30 40

3 deg

10 20 30 40

6, deg

Fig. 25. Aerodynamic characteristics of MU-2 spoiler (Effectiveness) 50 50 60 60 La 0.40 0.20 20 30 40 50 Flapoj o, deg 0=00 0=100 I St'lling angle of a t tac k)

Fig. 26. Aerodynamic characteristics of MU-2 spoiler (Hinge moment) L) La 0.002 o 0.008 0.006 0.004 0.014 0.012 0.010 0.008 0.006 0.004 0.002 0.002

Wheel turning angle (Left)

100 80 60 40 Flap 00! I i I 20 30 40 50 a (Stalling angle deg of attack) 149

Fig. 27. Aerodynamic characteristics of MU-2 spoiler

(Yawing moment)

Fig. 28 (a). Aerodynalnic characteristics of MU-2 spoiler _{Fig. 28 (b). Aerodynamic characteristics 1 MU-2 spoiler}

(flight test result) (Effectiveness) Flap O' _{(flight test result) (Effectiveness) Flap 45}

(f: Dale . 90 0l52Aug 960 o _{90 J} X C177 Sop 1964 S=45 With Sp tank 0.04-40 52 flog 964 Fr.* 20 e 40 377 6go 960 0.03 a o *0 i_____ I66 i-90--120 24 185 1.. 944 0.02 0.01 * * ay e 86 0* o 16e e n - 53

* t3. _{Wheel turning angle}

Wheel turning ongle (Left) _{(Right) 4 deg}

100 80 60 40 .20% 20 40 60 5 10 20 30 40 45

Yo001

tao 5, deg -0.02 .6 _0.03 0.04 0.08 0.06

4

0.02 a t, 96 a

Wheel turning angle (Right) O deg 20 O s 0.02 -0.04 -0.06 20 40 60 80 5 10 20 30 40 45 Os deg

TECHNICAL REVIEW May 1966

59

150

Fig. 29. Aerodynamic characteristics of MU-2 spoiler ((light test result)

I lap 0, V= 183knots (Hinge moment)

deflections and hinge moment characteristics in question

have been definitely improved for both flaps up and down configurations.

Finally, the time lag in effectiveness obtained from

flight tests is shown in Fig. 30. _{Although the data are}

widely-scattered, its average value in the normal _{range of}

flight speed for each flap position is approximately 0. 1

0. 15 sec and may be deemed to be satisfactory.

5. Conclusion

The aerodynamic characteristics of spoilers in general

have been introduced, and tile progress of research carried

out to surmount complicated problems and to bring them into practical use for tile MU-2 and tile results thereof

llave been outlined.

The MU-2 is the first airplane in the world which has adopted tile spoiler as a sole mentis of manual lateral control, and her high-speed as well as short takeoff and

landing performance which is incomparable with any other

( i ) Fischel, Jack and Ivey, Margaret F. Collection of test

data for lateral control with full span flaps, N. 1C'_l

TN 1404 (1948)

Wcnzinger, Carl j. and Rcgallo, Francis M. Wind

tunnel investigation of spoiler, deflector and slot lateral control devices on wings with full span split and slotted

flaps, NAGI TR 706 (1941)

Mungall. Robert G., Johnson, Harold 1. and Allord,

William 1. : A limited flight and wind tunnel investiga-tions of paddle spoilers as lateral controls, NASA TN

D-32 (1959)

Woods, L.C.: Theory of aerofoil spoilers, ARC R & M

2969 (1953)

Omori lukie: Spoiler, Journal of the Japan Society

for ile,-onautical and SJ'ace Sciences Vol. 1], No. 108

(1963-1)

Coleman, W. S. and Tidbury, G. II.: Some wind-tunnel developments of tile spoiler as a form of lateral control,

ARC R& M2586 (1942)

Arashi Kazuo: Wind-tunnel investigations of two-di-mensional spoilers, Mitsubishi Heavy Industries, Ltd.,

Nagoya Aircraft Works ReportNW-2533 (1962)

References (Left roll) 200 150 100 50 100 150 200 (Left roll) 200 150 0.3 FlaP 4t (Right roll) 0.1 Flap₄₅₁ (Right roll)

8 ) U.S.A.F. & Navy Bur. Aero. : Military specification (U)

Flying qualities of piloted airplanes, MIL-F-8785

(tSG) (1954-9)

(il) Federal Aviation Agency Airplane airworthiness; Normal. Utility, and Acrobatic Categories, Civil Aeronau-tics Ma,u,al 3 (1959-11)

Aoki Toshiro : Interim report on the characteristics

of spoilers on 1/3.5 scale half-wing model, Mitsubishi

Heavy Industries, Ltd., Nagoya Aircì-aft tVorks Report NW-2676 (1962)

Arashi Nazuo: Estimation of aerodynamic characteristics of the MU-2 spoiler, NW-2764(1962)of tite

above-men-tioned Report

Tanaka Kotsumi, Analysis of flight test results on the MU-2 spoiler (I),NW-3208 (1964) of the

above-mention-ed Report

Tanaka Katsumi: Analysis of flight test results on the

MU-2 spoiler (H), NW-3218 (1964) of _the

above-men-tioned1 Report

Fukumoto Kiichi : Analysis of flight test results on

hinge moment characteristics of the MU-2 spoiler,

NW-3379 (1965) ot _{the above-mentioned Report}

60

_{1fitszibisI, i ¡k-av y Industries, Lid.}

p o _r

100 50 100 150 200

V knots

Fig. 30. _{Aerodynamic characteristics of MU-2 spoiler} (flight test result) (Time lag in effectiveness)

airplane of her class is largely dependent upon this spoiler.

Since patents are pending at present (while have been admitted in the United States of America and Canada. the presentation of data is limited to the extent necessary

for understanding tite outline.

As spoilers are iLlrthcr improved, the improvement of

airl)lane performance would be promised hereafter.

There-fore, spoiler researcil is still _{being continued to make}

the spoiler one of the representative features of the

airplanes developed by our Company.

Ii 0,2

Bu