C.P. No. 205 [I 3,878)

A.R C. Technical Report

C.P. No. 205 (13,878)

A.R C Technml Report

MINISTRY OF SUPPLY

AERONAUTICAL RESEARCH COUNCIL

CURRENT PAPERS

Full Scale Measurements of Impact Loads

on a Large Flying Boat

(Sunderland Mk.5)

Part II - Results for Impacts on Main Step

BY

J. A. Hamilton

LONDON HER MAJESTY’S STATIONERY OFFICE

1955

FIVE SHILLINGS NET

C.P. No. 205

Report No. F/R&220

Febmar.y 1951

JI.NIRE AIFlXiE'T EXF'EREWWAL ESTABLISBMEXI', R.A.F., F"wLMST'X3

Full Scale Measurements of Impact Loads on a Large Flyir~ Boat (sunaerlena Nkk) ---

Part II - Results for Inqacts on Mai- --.-

J. A. IWdIIIpON

SUMMARY ---

Full scale xeasuremnts of landing impact forces and pressures have been made on the hull of a Sunderland Mk.5 flying boat (weight 50,000 lb) in order to provide basic information on the agreement between experiment and. the latest available impact theories. The ex- periments were arranged to give impact conditions as rx3s.r as possible to those assumed in theory.

The results revealed a marked discrepancy between the form of the total impact-tin!e curve predicted by theory, and that measured on the aircraft. In particular, the measurement of time to reach maximum impact force was about twice that indicated by theory. The magnitudes of thetheoretical and measured maxiwm impact forces were in reasonable agreement. This discrepancy may be attributable to the neglect of after- body influences in the theoretical analyses.

Measurement of the intensity of maxinnam hydrodynamic pressures on the planing bottom confirmed that pressure and velocity ccrmponent normal to the keel may be related by an expression of the form

where

%I = the local deadrise angle in degrees

r" = the density of water in slugs per cubio foot

vn = the velocity at the tim and position at which k is measured (f.p.s.).

The experimental value for K is 132 when & is given in p.s.i.

The distribution of pressure from the keel to the maxinaun pressure

/point . . . . .

- 3 -

CONTENTS

lb Introductmn

2.1. iiircraft

2.2. Apparatus

2.2.1. Total force measurement 2.2.2. Planing bottom pressure measurement 2.2.3. Measurement of verticsl end. horzzontal velocities 2.2.4. Measurement of keel attitude and angle of roll 2.2.5. Recording

3. Range of Tests and Piloting Technique

4. 7eather Conditions

5. Results

5.1. Total impact forces

5.2. Local pressures 31~3 pressure distribution

Psge No.

8

8

11

11

11

5.3. Comparrson with other theoretical and experimental investigations

5.3.1. Full scale experimental 5.3.2. Theoretical

6. Discussion

6.1. Total Impact Forces

14

6.1.1. The effect of planing bottom shape 6.1.2. Chine wmers~on 6.1.3. Hull and wing flexibility 6.1.4. dtarbody effects 6.1.5. The effect of rotation UY pitch

6.2. Pressures

7. Design Implications

8. Conclusions

17

17

References

/Lid Of Appedices . ..**

- 5 -

LIST OF ILLUSTRATIONS

Title

Sunderland Mark 5 Flying Boat

Aocelerometer Pick-up Positions

Pressure Pick-up Positions

Typicai Larding Impact Record

Non-Dimensional Plot of &ax.imum Impact Accelerations

Non-Dimensional Plot of Time to Ma.ximum kCeleratiCn

Comparison betseen Measured and Computed Acceleration-

Time Curves

Figure Nor

1

2

3

4

5

6

7a, b, o & d

Comparison between Typical Main Step and Rear Step

Landings

Measured Naximm Local Pressures (Rows A, B, C and D)

Measured Maximum Local Pressures (Row A)

Measured &.xiwm Local Pressures (Row B)

Measured Transverse Pressure Distributions (ROW A)

Transverse Pressure Distributions Deduced from Piok-up

No.16 (Row A)

8

9a

9b

90 10

Measured Transverse Pressure Distrc.butions (Row B)

Transverse Pressure Distributions Deduced from Pick-up

No*9 (Row B)

II

12

13

Maximum Acceleratxn-Comparison between Reference 3 Theory

and earliar Pull Scale Tests

Time to INaximum Acceleration - Comparison bet-veen Reference 3

Theory and Earlier Pull Scale Tests

Maximum Kaoeleration - Comparison bebeen Reference 8 Theory

and Sunderlard fill Scale Tests

Time to Maximum Aooel~aticn - Comparison between Reference 8

Theory and Sunderland Full Scale Tests

Comparison between &celernticns tleasured at Various Points

in the Aircraft Structure

14

15

16

17

Typical Example of Low Pressure Region

Typical Pressure-Time Records for One Impact (Rcw A)

18

19

20

/Comparison ti.*~.

- 7 -

&ST OF SY@BOLS

K

%

P

hS%

w

vn

vT

BI

2

Constant in Wagner's maxmum pressure formula

Assoc2ated mass factor

Hydrodynamic pressure p,s.i.

Maximum value of hydrodynamic pressure p.s.i.

Aircraft &l up weight lb.

Velocity component normal to keel f.p.8,

Velocity component parallel to keel fapss.

VT~~,"T (~b;onr,~;;i;;~~$ to conditions

$ whore c is the wetted half beam and x the distance from the keel to the point at which pressure is bexng measured or deduced

Deadrise of line Joining keel to chine

Local daadrlsL at any pant on the hull planing bottom

Incidence of keel to water surface

/Introduction ..w..

-9 -

techniques and their accuracies and ls.mitations, but merely as a summary sufficient to yxve coherence to the later discussion without necessitating reference to Part I of the report,

2.2.1s Total force measurement

Ths total impact force was measured by a number of variable inductance type accelerometers mounted at various positions along the wing span, Fig.2. In all, four accelerations mere measured in each landing i-

(i) The acceleration at a point on the wing centre section (front spar, lower bcom).

(ii) The acceleration at a point on the front spar, starboard wing, correspondIn& approximately to the ncdal point of the furdamental wing vibration mode,

(iii) The acceleration at a point on the front spar, port wing, corresponding approximately to the nodal point of the fundamental wing vibration mode*

(iv) The resultant acceleration obtained from three accelerometers whose outputs were so combined as to eliminate the fundsmental and first harmonic modes of wing vibration giving a final record of the hydrodynamic impact force modified by only higher modes ofting vibration (cf. Fig.2).

The necessity for this ccmplication in measuring acceleration was indicated by the eerlier structural testslwhich showed that wing vibrations could modify severely the shape of the hydrodynamic impact acceleration-time curve. Acceleration measurement (i) gave merely the resultant hull accelaratxon including any wing vibration effects. Acceleration measurements (ii) and (iii) were intended to eliminate as simply as possible the wing fundamental mode and to indicate the effects of roll.

The principle behind accelercmeter measurement (iv) is fully described in Reference 1 where it was utilised to eliminate wing vibration modes from a centre section accelerometer record. For the present tests the scheme has been modified so th?t instead of obtaining the hydrodynamic impact acceleration-time curve from ;cn analytical combination of three separate accelerometer records, the electrical outputs of the three accelerometers are combined in calculated proportions and the resultant output gives the required acceleration-time curve directly.

2.2.2. Planing bottom pressure measurements

Hydrodynamic pressure measurements were made on the Porebody planing bottom by means of diaphragm type pressure pick-ups of the type used sue e sfully for a similar purpose in the hull launching tank at IL4.E.E.~'~ Briefly, the intensity of pressure at a point in the planing bottom isrcgistered by the deflection of a thin, circular german silver diaphragm (I” diameter) fitted flush with the bottom skin. The di-~phragm movement is transmitted mechanically to a small strain-gauged beam of beryllium-copper.

Twenty pick-ups were installed, all of them on the starboard side of the forebody (Fig.3).

/Each . . . . .

- 11 -

3. Range of Tests and Piloting Technioue

The primary objective of the tests wes to obtain landing impacts which fulfilled as far es possible the conditions assumed in theoretical analyses. These are :-

(i) Zero normal (or vertical) acceleration prior to touchdown,

(ii) Zero drift velocity prior to touchdown.

(ii=) Zero angle of roll during impact.

(iv) Zero angular velocity z.n pltch during impact.

(v) Main step only immersed.

The first of these oonditlons was usually satxsfled by maintaining fixed elevator setting, power condxtions and forward speed from a height of about 100 feet to the touchdown point. The second and third conditions apply to s.ny good landing and. were achieved by accurate handling of the aircraft in the approach. Unfortunately the pilot has little control over the fourth condition onoe the impact has started. Experience showed that with zero or slzghtly negative elevator sngle an impact with zero pitching veloolty nas most like18 to be achieved if the keel attitude at touchdown was in the region 2'-5 . Occasional pitching did occur even in this range howcvvor. The pilot can do little about condition (v) apart from ensuring that the maln step touches first.

The requrrements gzven to the pilot were, therefore :-

(i) Elevator flxed, engine power constant, forward velocity constant from 50-100 feet downwards.

(ii) Approach speed higher than usual in order to achxeve a low attitude Impact.

(iii) No check before touchdown.

No attampt was made to specrf'y rate of descent because of the relative inacouraoy of the standsrd rate of descent meter. Landings were specified as heavlzr or lighter than the prev~.ous one. LViost pllots dxd use the rate of descent meter as ir guide during their appronch. Frequently the aircraft bounozd clear of the water after the first Impact and pilots were encouraged to re-land straxght ahead.

All the tests were made nt one weight - 50,000 lb - and one centre of gravity position (3.0 feet forward of the mnln step point parallel to hull datum).

4* Weather Conditions

A o&n sea was essential for this first investlgatlon and fortunately during the 3 or 4 days occupied by the flxght tests the wind strength averaged 3-4 knots wxth occasional gusts up to 8 knots. The sea surface was flat calm for the majority of landings, with a few made in 61' wavelets. Care Was taken to allow ship washes to die away before larding.

5. Results

5.1. Total impact forces

The theoretical work of Reference 3 has been chosen as a sultable basis upon wh-rch to illustrate the variation of total hydrodynamic force

/with . . . . .

- 13 -

The pressure distributions were less amenable to concise presentation than the maximum pressures. Two methods of obtaining experimental distri- butions have been employ& Figs. 10 ard 12 show, plotted in non- dimensional form the transverse distributions obtained from pressures indicated simultaneously on several pressure pick-ups in rows A and Be The runs chosen for plotting are thos e for which reliable information is available from all the pressure pick-ups concerned.

Figs. 11 and 13 show transverse distributions obtained from the pressure time histories of one pick-up in each row by assuming that the pressure wave has a constant velocity past the pick-up for the time intervnl considered. The pick-ups plotted were chosen at random from all the results available. This second method was included because the first method, though more conventional ati convenient, has the disadvantage that only three or four points on each distribution curve are known and slight calibration or response errors between individual pick-ups in the same row may cause scat&r <and thereby mak e the drawing of a fair curve through these isolated points difficult.

In all four figores, comparison is made with the theoretical distri- bution of Wagnzr's theory, given by the expression

p = +vn2

where

C = wetted width x = distance from keel

Owing to the dtioulty of defining the wetted edge of the measured pressure wave, the maximum pressure position has been chosen as a common point for comparison of theoretical and axpzrimentaldlstribution. In Pigs. 10 and 12 the distributions have been taken when the keel-maxumzm pressure distance was about 3 fait i.e. 0.6 beam, In Figs. 11 and 13, the peak pressure position has been made to coincide with the position of the pick-up being considered,

The pressure curves deduced by method one confirm the maximum prtssurc r:sults in that the pressure magnitudes for row 11 lies slightly above the theoretical curve whereas those for ran B lie on the theoretical curve or slightly below it. hgs. 11 and 13 give a more precise picture of the agree-e& between the shapes of distribution curve given by theory and experiment. There 1s good agreement in the region between keel and maximum pressure but the experimental curves show a slower build up from the wetted edge to maximum pressure.

5.30 Comparison with other theoretical a.experimental investigations

5.3.1. Full scale experimental

A parallel series of full scale impact experiments was made by the N.A.C.A. on an amphibi man step deadrise of 20'. ?

n having an all up weight of 20,000 lb 3rd a The results from these tests were re-analysed

on the basis of' Heference 3 theory and they are presented in this form in Fxgs. 14 ani 15.

The maximum impact accelerations follow the same trcrd as thy British experimental-theoretical curve. Between values of - 0.6 and x = 0.8 the experimental peak loads lie wall above the thecr%i&l curve, a fact which was noted in the orzgina.1 report and attributed to the effect of chine turndown m Impacts whare tine immersion ocourred.

/The.....

- 15 -

Of these, the last ma.y be inmediately discounted since the curved portion is rarely immersed before the instant of maximum acceleration.

For all the computation of force parameters a mean deadrise of 26' was utilised although in practice the dbadrise v,aries from 30' at the keel to ly" at the chine. To obtain some gauge of the effect of varying deadrise on the force-time curve, theoretical ourves for typical impacts were calculated for a deadrise angle of 30' as well es 26'. These are compared with the experimental curves in Fig.7 and they confirm the small effect of deadrise variation be&been 260 and 3Oo.

In Reference 3 Crewe and Mona&m mmme that the associated water mass for a wedge wrth a transverse st

(A&~ p is proportional to the quantity

perimeter and they further suggest that for a vce plan form thezr treatment should be used Rith the nssoclirttd mass based on the EYpprOpriCLte value of

(Area) 2 perlmcter perlmcter

This reasoning has been appl~td to several typical Sunderland impacts This reasoning has been appl~td to several typical Sunderland impacts and the overall result is to bring about a decrease of 59 m the experimen- and the overall result is to bring about a decrease of 59 m the experimen- tal values of B. (non-dlmenszonal time parameter) brznglng the experimental tal values of B. (non-dlmenszonal time parameter) brznglng the experimental points nearer the th-oreticel curve of P&.6; and a similar increase in the experimtntalvalues of A. bringing the experimental poznts further above the theoretloal Curve. (cf. Flg.5 and Append= III).

6.1.2. Chine immersion

The presence of chine immersion appears to have no consistent effect on either maximum acceleration or time results (fiilga. 5, 6 and. 7). When it does oocur, the chine imtnerslon is small ancl takes plaoe well after the theoretical time of maximum acceleration.

6.1.31 Hull and wing flexibility

For a complicated structure such as that of the Sunderland hull and wing, the effect of hull flexrbllity on the Impact acceleration- time curve can only be computtid by making preluninsry estimates of various structural constants and then computing their effect by a laborious step by step method, Fortunately there are two items of exptirimental evidence mhioh indicate that for these partlculer full scale impacts, hull and v{ing flexibility have little effect,

The first of these is illustrated in Fig.18 which canpares the acceleration-time curves obtained from accelerometers at various points in the hull and wing for two typical impacts. These figures confirm that the wing vibrations were not sufficiently excited to produce appreciable differences up to the point of maximum acoeleratlon.

The seoond piece of evidence is contaIned in Fig.14 of Reference 1 which shows that the effect of hull flex0oility is negligible, oertalnly for the region near the main step.

6.1.4. AfterbodY effects

The effect of the afterbody in modifying the sample impact theory has not reoceived much notice in tieoretlcal-experimental conparlsons. It is slgnifrcant, however, that the N.A.C.A. model tests which gave good agreement batneen theory and experiment in nearly every respect, mere conducted on forebodles alone.

Tr;o forms of afterbody interference are possible. In rear step first impacts, the afterbody absorbs some of the initial energy of impact and pauses the hull to pitch fomtard onto the main step (Pig.8, Run 19).

/Ladings .,...

- -I7 -

The difference between theory and experiment Ln the peak to v&ted edge region mey be attributed sjmpIly to differences in the physical conditions assun& by Wagner and those achieved in practice, The dis- agreement is of small significance in applying the results for purposes of structural design.

The exact shape of the measured wetted edge is interesting, Fig.39 shows that by the time the pressure wave reaches pick-up No. I8 of row A there is a region of low pressure Izzfore the rapid build-up towards the peak* This low pressure region will certainb invalidate eqv attempt to measure pressure areas and "splash up" values by means of water contact devices alone. Fig-20 i&&rates the growth of fltch a 10nr pressure area as the pressure wave proceeds towards the chine.

7. Design Indications

The detailed deduction of the design loads from basic theory is beyond the scope of this report and in arq case the range of variables cover& &I too small to justify the general applicability of such deductions. However, the results do give rise to a few design problems which should be stated,

For the estimation of overall hydro&ynamic impact loads, the theories of References 3 and 8 appear to give values which agree sufficiently close&y with the measured results for the purpose of desi@. TEe discrepancy in times to maxirmrm load is not serious per, dess account has to be taken of the structural response to dynamic loads. However, it is disturbing in that it may imply a antal disagree- ment between theory and experiment, and the theoretical estimates should be used with some caution therefore, in applications where the conditions differ greatly Prom those of the present tests.

Unfortunately the time discrepancy affects the derivation of design frame and plating pressures to a much gresiter extent than it does the derivation of total impact load. For these, the theoretical formdae are given in term.9 of V nr the local normal-to-keel velocity, and to be of design use some relationship must be found between oVn - the initial norms1 to keel velocity, and V,, or between oVv and Vv Aince Vh is constant. Such a relationship may be obtained from the Reference 3 theory but this differs considerably from the experimental variations as the examples quoted. in Fig.21 show,

The magnitude of the error inverticalvelccity predicted for four typical landings is shown inFig.22. Fig.23 shows that tb corres- ponding errors in p and pmax mey amount to IS-20$ for values of Vv above 0.5vv,.

The relationship between peak pressures - confined to a small planing bottom area - and. design pressures over larger areas is examined in Appendix N and a simple expression is there deduced for the relative magnitude of peak and mean distributed pressures. Fig.24 illustrates this with reference to a range of deadrise angles.

8. Conclusions

The form of impact force-time curve given by these full scale measurements differs from that indicated by current theories. In partlcuXar, the theoretical time to reach maximrun impact force is almost half that given by measurement. The rpagnitudes of the theoretical and measured maxinnun impact forces are in good agreement. Some of these

/d.iscrepaancies . . . .

- 1y -

No. Author(s)

1 A. Burns A. J. Fairclough

2 J. A. Hemilton

3 P. R. Crewe R. J. Monaghan

4 J. A. Rardlton

5 J. W. McGvor

6 J. A. Hamilton J. W. McIvor

7 Margaret F. Steiner

a Benjaman MilwitzaIqy

9 J. A. Hamilton

IO J. A. Hamilton

11 John D. Pierson

List of References

Title, etc.

l&wmicl~loads of flying boats. With special reference to measurements made on Sunderla.n3 TX. 293. R. & Ivi. 2629. February, 1948.

A comparison between some fW.1 soale lsnding upact measurements and two impact theories. Report No. F/Res/211. A.R.C. 11,345. February, 1948.

Formulae for estomatlly the forces in seaplane water impacts mthout rotation or chine immersion, R. 6s M. 2804. ~~XSZ.Y, 1949.

Note on a proposed programme for full- sale seaplane water tipact tests. Report No. F/Res/212. A.R.C. 11,739. June, 1948.

Full scale measurements of impact loads onalargeflyingboat. PartI- Description of apparatus and instrument installation. c.P. 182. Msrch, 1950.

Measurements of impaot pressures on the hull of a model seaplane. Report No. F/Res/215. A.R.C. 12,703. Juti, 1949.

Comparison of overall impact loads obtained during seaplane landing tests with loads predicted by

% drodynamic

theory. Report No. NACA N/l 781. January, 1949.

A generalised theoretical and experimental. investigation of the motion end ~drodynsmi~ loads experienced. by Vee-bottom seaplanes during step lending impacts, Report No. NACA~N/l516. February, 1948.

An rnvestigation into the effect of after body ventilation on the k@rodynemic characteristics of a anall flying boat (Sam 37) with a I:20 faking over the !nain step. R. Pe M. 2714. November, 1947.

An &term report on the hydrodynamic performance of a large h-engined flying boat (Sunderland Mk 5) with a 1:16.75 main step faimng. Report No. F/Res/214. A.R.C. 12,162. Janusry,l949.

On the pressure distribution for a wedge penetrating a f!luGi surface. Stevens Institute of Technology Experimental Tpuwing TankReport No.336.

APRNDIX II

Wagner's Formulae for Distributed and Maximum Pressures on ~~11s having Transverse Curvature

The general form of' Wagner's formula for the distrlbutlon of hydro- dynamic pressure across a hull is

For the landings under oonslderatlon in this report the exPressIon

is small enough to be neglected without loss of accuracy.

Prom this modified equation may be deduced the 'Wagner expresslon for maximum pressure,

Pm = 4 P V2

[ -+-+I

For a hull of constant deadrise

and expressions (1) and (2) become

P = "P 2 [ n- cot 8 2 2 ,/pyj-r f -22

I

PmsX = +2 [

($ cot8)2 + 1

I

(2)

(3)

For simplzcity in analysis expressions (3) and (4) h3ve been applied to the Sunderland planing bottom and the effect of curvature has been allOWed for by assumzng that8 is the value of the local deadrIse at the point of the planlog bottom being considered.

Let US examine the error involved in this assumption. 11

Wagner deduces that for a hull of curved. oross sectun

Q = +Bo + B,C + B2C2

where B,, B,, etc. are given by the equation for hull cross-seotlon.

Y = Box + B,x * + B2x 3

For the full scale tosts it has ken assumed that

(5)

(6)

where is the local desdrise,

- 23-

XJPEXD'IX III

Estimation of the Effect of a Vee-shaped Step on Total Impact Forces and Build-up Time

According to the theory of Reference 3 the non-dlmenslonal impact load factor A,, is given by the expression

Of all factors on the right hand side K,s is the only one directly affected by hull form and for fixed values of draft, attitude snd de&rise

Kd (areal perimeter

For a 24' Vee plan shape, a msan deadrise of 26' and a keel attitude of 5' the ratio of K values is

K1 vee Kq transverse

K, vee

I

4

Kq transverse

= 0.86

= 0.95

Hence the theoretIca effect of aVee-shape mould be to increase the experimental values of Ao plotted in Fig.5 by 2pproxlmataly .?J$

Similarly, the non-dimensional time factor B. is given by the expression

BO = t,

K,$ vvo

w 3 ( I

00s~~ fg

and the theoretical sffcot of a a0 vee-step 1s therefore to decrease the experImenta values of Bo given in Fig.6 by .5$.

/Appendix IV . . . . .

- 25 -

TABLE1

Beam (max) Length (F.P. to Rear Step) Length:Besm Ratio

ft. ft.

Forebody Length (F.P. to Main Step Keel) ft. Afterbody Length (Main Step Keel to Aft

step) Keel-Chine Deadrlse at Main Step Step Plan Included Angle Forebody Keel - Hull Datum ilngle Heel - Heel Angle Forebody Keel - Aftwbody Keel Angle Main Step Fslring Ratlo

ft.

Area (gross) sq.ft. 1687 Spa f-t. li2.8 Inc4ence to Hull Datum 9 9’ Sectron Gottlngen 436 modified

Flaps

5Pe Area

Area (including elevators) Elevator area (lncludlng tabs) ELevator movement

9.79 62.12

6.35 32.94

2;ga 1320 0

$ 17' 7O 29’ 6:l

sq.ft.

sq.ft. sq.ft.

Gouge 286

205 84.5

16O 30' up and down

Engines

4 Pratt Whitney Twm Wasp R.1830~90E givxng 1200 B.H.P. at 2,700 r.p.m. and + 9 lb/sq.in. boost for sea level take-off.

Loading

At A.U.WtTt. 50.000 lb

C. G. "Normal" is 3.02 ft. forward of main step at keel parallel to hull datum line.

Run No.

1

2

3

4

5

6

7

8

9

IQ

11

12

13

14

15

16

17

15

19

2-o

21

22

23

Impact NO.

I

1

2

I

2

1

2

2

1

2

3

1

2

1

1

1

1

1

2

2

1

1

I

V-J P .pfs. 6.8

6.4

5-2

6.5

2.9

5.5

3*5

6.8

8.0

3.8

6.3

7." 4

4.7

5.0

4.7

6.0

5.8

9.0

4.6

3.2

5.5

5.6

4.1

- 27 -

TAEiLE III --

DE,TAILS OF INDIVIDUAL LANDINGS

Mean A.U.Wt. 50,000 lb

Vho T f.P.Sl Deprees

148 2.3

138 52

110 9‘2

153 2.0

114 9.8

140 4.7

120 9.5

112 10.3

142 5*8

120 9.5

97 9.9

129 4.4

115 9.5

128 4.2

146 4.7

142 3.5

159 3.2

134 4.6

116 11.8

109 8.3

122 11.4

130 7.0

134 7.0

Angular W-&k

3

0

-3

0

-4

+4

-3

-5

+6

-2

-4

+4

-3

0

0

0

0

0

-8

-2

-8

0

0

TV-J- did max

CR)

0.94

1.15

1.21

0.94

1.12

1 .I0

1.02

I.39

1.3a

0.80

1.25

1.20

0.97

0.70

0.69

0.81

0.80

I.40

1.11

Q.56

0.95

1.2

0.67

tmax se05

0.38

0.40

0.48

0.30

0.59

0.38

0.50

0.39

0.33

0.88

0.39

0.34

0.61

0.32

0.40

0.30

0.35

0.34

0.55

0.75

0.55

0.46

0.52

Xun No.

17

18

22

23

?ick-Up No. enlax.

pSS.1

Tme to ?UlC.X - se

10.0 0.320 14.8 0.158 10.0 0.142 14.1 0.095 11.8 0.184

3

cz 9

11 14 15 16 17 18

17.7 0.206 16.5 0.215 22.5 0,120 18.5 0.109 18.2 0.224 25.0 0.095 20.0 0.070 22.1 0.127 25.1 0.174 24.5 0.250

9 IO 11 14 15 16

2

28.7 0.198 29.3 0.276 33.1 0.368 27.2 0.150 25.1 0.135 30rl 0.173 37.3 0.236 29.5 0.329

15 24r5 0.205 16 28.7 0.300 17 27.5 0.430

- 29 -

TABLE IV contd.

Mnximm Pressure Hcsults

Vv f.p.s*

2.2

;:j 510

4.5 2.9

::;

::r,

‘;‘z *

3.6 2.7 0.9

Vt f.p*s.

158.4

133.0

128.1

133.3

If degs vn f.P.S.

::;5 ;:;

12.4 15.2

::*z j4:8

4.8 4.8 4.4

44:: g:i . 44::

17.9 17.5 q8.8 18.7 17.3 19.0 19.2 18.6 j8.4 16.5

::; 7:: ::: 7.5 7.8

21.3 lY*Y 19.8 21.7 21.9 21.5 20.9 13.1

7.2 20.4 7.1 19.4 7.4 18.4

P mzc (cot2d-+ 0.405)

3.0 4.7

::1”, 3.2

5.L _ ‘;:: 5.8

‘;:; 66:: 2:; 7:: 26’ 7.9 8.2 8.8 5.4

2;

FIG. 1.

SUNDERLAND MK.5. FLYING BOAT.

FIG.3. PLANING eorfo~ CONTWRS.

FOR ADDITIONAL DETAIL5 OF PICK UP POSTIWC 5CL TMU IL.

PRESSURE PICU UP POSITIONS

+ WUE lHMERSY)U

b DoUbl’fUL CWL lMhtERS\41 - J J

EYtWE EYtWE FlaURE5 bESIDE THE POIUTS REFER FlaURE5 bESIDE THE POIUTS REFER To THE MEAN ANGULAe VELOCITY To THE MEAN ANGULAe VELOCITY bETWEEN TOUCH DON’N AND MNb4LlH bETWEEN TOUCH DON’N AND MNb4LlH ACCLLERATION ACCLLERATION

+ + NOSE UP NOSE UP

NOSE DOWN NOSE DOWN

0-62 0-62

iL iL

04 04 0.4 0.4 03 03 o-2 o-2 0-I 0-I 0 0

NON DM3+JSlONAL PLOT OF MAXIMUM IMPACT ACCELERATIONS NON DM3+JSlONAL PLOT OF MAXIMUM IMPACT ACCELERATIONS

RUN 10 0

MEASUPED FULL SCALE MEAN AWLAR VELDCITY ZERO

------ FROM OLF, 3 THE&v t6’ DEADRISE

0 0 M M nut cpoh4 roucn nmw - xc.

RUtJ17 FIG.78 0

- MCAWRED FULL SCALE I MEAU MULAP VfLDCW Z= __

COMPARISON BETWEEN MEASURED AND COMPUTED

ACCELERATION-TIME CURVES.

! Q .- 3

P

RUN I8

d

\

MlNnE 7-

UMPARISON BETWEEN TYPICAL MAIN STEP AND REAR STEP LANDINGS.

FIG. 9&

0 430 aao 400 v:

b

0

MEASURED MAXIMUM LOCAL PREP. ROW A.

O*lO r 008 -

I I I I /z//-h

0.06

- ---__- TWEOR~C~L (WAGNER)

MEAWRED ON INDIVIDUAL IMPACTS

- NOTE :- EACU MEASURED DlSlRlBUTlON

WAS BEEN TAKEN A-T Atd INSTANT

Wl4Eb.l -WE WETTED WLDTU WA5

APPROXIklATELY ONE HALF HULL BEAy.

0 0.2 04 0.6 O.t3 IO 1.2 I.4 1.6

7

MEASURED TRANSVERSE PRESSURE DISTRIBUTIONS ROW A.

FIG. 12

/

\ \ \ \ \ \ \ \

. 8.

.

6 .

f

d

/ .

0 1 I I I 0.9 &8 0’7 0' 6 0’5 o-4 0.3 o-2 0.f 0

?L MAXIMUM ACCELERATION

COMPARISON BETWEEN REF 3 THFQRY AND EARLIER FULL SCALE TESTS(REF.7)

1

Ce

0 I.0 Q-0 3.0 4-a

RI t+i cos(t + u.)

MAX IMUM m&RATION COMPARISON BETWEEN REF.8 THEORY AND

SUNDERLAND FULL SCALE TESTS.

,5 CL =lt urWl)+ (WWL9 *, ,*1 mp b) FIG. 17 . I I I 0

)ATlON COMPARISON BETWEEN REF.8 THEORY AND

SUNDERLAND FULL SCALE TESTS.

FIG. 19. 30

. 20

; 0:

IO

0 IO 20 30 4.0 50 60 MEL - *

DISWNCE INS. CHINE

-

PICK UP N- 10.

-LOW PRESSURE

REGIOH.

c

TYPICAL EXAMPLE OF LOW PRESSURE REGION.

FK3.20.

0 0~10 040 040 o+o

TIME FROM I*’ IMPACT. - SEC.

0.50 0’60

TYPICAL PRESSURE TIME RECORDS FOR ONE IMPACT. ( Row A.)

40 40

30 30

20 20

IO IO

RUN NO

0 02 0.4 t

0.6 oe

7”” = 0.

PERCENTAGE DIFFERENCE BETWEEN MEASURED AND THEORETICAL VERTICAL VELC>CITlES DURING IMPACT.

TWLORETICAL Vv ASWMLD TO DC THE WAN DIFFCRCNCES INOKATCD IN FW22.

DEOUCEO FROM WNDERLAND WING LtFT.

TYPICAL ERRORS IN PRESSURE ESTIMATION.