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-228 FLIGHT AUGUST 26TH, 1943 The Junkers Junto 211 Series Captured Heinkel He IIIH and Junkers Ju 88A.1 Power Plants Examined 1 I LLUSTRATED descriptions of the German Jumo 21 IA aircraft engine have previously appeared in Flight, the most important being a detailed and fully illustrated description of the main feature of interest, viz., direct-fuel injection, in our issue dated January 18th, 1940. In our issue of August 5th, 1943, we published brief results of bench tests which the Ministry of Aircraft Pro- duction has had made on Jumo 21 ID engines taken from a Heinkel H e m . Following is an abstract from M.A.P. reports on the engine. The 2HA engine, fitted with a two-speed supercharger, has 12 cylinders, arranged in inverted-Vee formation, and is liquid-cooled (Glysantin-water mixture), with direct-fuel injection into the cylinders and spark ignition. The air- screw is driven through spur reduction gearing, both the driving and driven gears being splined to the shafts and centralised by split bronze cones. The driven shaft is mounted on a roller race at the rear and on a combined roller and thrust race at the front housing cover. Pro- vision is made for a cannon firing through the airscrew shaft. Auxiliaries and accessories are driven through a train of gears in a wheelcase at the rear of the engine. A combinad hand and electric starter is fitted. The general design follows established practice, but in- teresting features worthy of notice are the cylinder heads incorporating cooled exhaust ports and exhaust valve guides, and also the method of attaching the cylinder liners to the head, the position of the supercharger, the design of oil scraper piston rings and the use of single-piece split- cone cotters for valve-spring caps. Dealing with these in the above order, the cylinder head for each bank is a single-piece aluminium-alloy casting in The engine mounting is of magnesium alloy forgings supported by tubular steel struts. Cooling the exhaust. The exhaust port is completely jacketed, and cored passages are provided around the exhaust-valve guide. which the camshaft bearing pedestals are cast integrally. The combustion chambers are flat-topped and have two inlet and one exhaust valve per cylinder. Bronze valve guides are inserted ; the exhaust valve guide passes through the water space and is a press fit in the opening into ttoe combustion chamber. The pressure joint is made on Sc aluminium washer under the shoulder of the guide. Wafer leakage at the camshaft end of the guide is prevented by a rubber ring in an annular groove. The steel valve- seating rings are conical externally and are pressed into the head and rolled into a taper at the inner end; the exhaust-valve rings appear to be " Stellite "-faced. Provision for Four Plugs Two sparking-plug holes are provided on each side of the cylinder head, although two plugs only are fitted. The fuel-injection nozzle is situated on the centre line, at right angles to the crankshaft. The nozzle is screwed into the cylinder head and is liquid-cooled. The intricate nature of the cylinder-head casting is illustrated, and its will be noticed that the exhaust port is completely jacketed, and that cored passages are provided around the exhaust-valve guide and injection nozzle. Preliminary examina- tion of the casting sug- gests that it is of good quality and that con- siderable skill is neces- sary for its manufac- ture. Liners of 45-ton steel are bolted to the cylin- der head by four long studs of 60-ton steel, the head itself being secured to the cylinder block by fourteen studs. The engine is fitted with a two-speed centri- fugal supercharger, the air intake of which faces forward and is protected only by a gauze screen. An un- Cylinder liner. Four long studs draw the liner against the cylin- der head into which the liner is spigoted.
Transcript
Page 1: Junkers 211.pdf

-228 FLIGHT AUGUST 26TH, 1943

The JunkersJunto 211

SeriesCaptured Heinkel He IIIH

and Junkers Ju 88A.1 PowerPlants Examined1

ILLUSTRATED descriptions of the GermanJumo 21 IA aircraft engine have previouslyappeared in Flight, the most important

being a detailed and fully illustrated description of themain feature of interest, viz., direct-fuel injection, in ourissue dated January 18th, 1940.

In our issue of August 5th, 1943, we published briefresults of bench tests which the Ministry of Aircraft Pro-duction has had made on Jumo 21 ID engines taken froma Heinkel H e m . Following is an abstract from M.A.P.reports on the engine.

The 2HA engine, fitted with a two-speed supercharger,has 12 cylinders, arranged in inverted-Vee formation, andis liquid-cooled (Glysantin-water mixture), with direct-fuelinjection into the cylinders and spark ignition. The air-screw is driven through spur reduction gearing, both thedriving and driven gears being splined to the shafts andcentralised by split bronze cones. The driven shaft ismounted on a roller race at the rear and on a combinedroller and thrust race at the front housing cover. Pro-vision is made for a cannon firing through the airscrewshaft. Auxiliaries and accessories are driven through atrain of gears in a wheelcase at the rear of the engine. Acombinad hand and electric starter is fitted.

The general design follows established practice, but in-teresting features worthy of notice are the cylinder headsincorporating cooled exhaust ports and exhaust valveguides, and also the method of attaching the cylinder linersto the head, the position of the supercharger, the designof oil scraper piston rings and the use of single-piece split-cone cotters for valve-spring caps.

Dealing with these in the above order, the cylinder headfor each bank is a single-piece aluminium-alloy casting in

The engine mounting is of magnesium alloy forgings supported bytubular steel struts.

Cooling the exhaust. The exhaust port is completelyjacketed, and cored passages are provided around the

exhaust-valve guide.

which the camshaft bearing pedestals are cast integrally.The combustion chambers are flat-topped and have twoinlet and one exhaust valve per cylinder. Bronze valveguides are inserted ; the exhaust valve guide passes throughthe water space and is a press fit in the opening into ttoecombustion chamber. The pressure joint is made on Scaluminium washer under the shoulder of the guide. Waferleakage at the camshaft end of the guide is prevented bya rubber ring in an annular groove. The steel valve-seating rings are conical externally and are pressed intothe head and rolled into a taper at the inner end; theexhaust-valve rings appear to be " Stellite "-faced.

Provision for Four Plugs

Two sparking-plug holes are provided on each side ofthe cylinder head, although two plugs only are fitted. Thefuel-injection nozzle is situated on the centre line, at rightangles to the crankshaft. The nozzle is screwed into thecylinder head and is liquid-cooled.

The intricate natureof the cylinder-headcasting is illustrated,and its will be noticedthat the exhaust port iscompletely jacketed,and that cored passagesare provided aroundthe exhaust-valve guideand injection nozzle.Preliminary examina-tion of the casting sug-gests that it is of goodquality and that con-siderable skill is neces-sary for its manufac-ture.

Liners of 45-ton steelare bolted to the cylin-der head by four longstuds of 60-ton steel,the head itself beingsecured to the cylinderblock by fourteenstuds.

The engine is fittedwith a two-speed centri-fugal supercharger, theair intake of whichfaces forward and isprotected only by agauze screen. An un-

Cylinder liner. Fourlong studs draw theliner against the cylin-der head into whichthe liner is spigoted.

Page 2: Junkers 211.pdf

AUGUST 26TH, 1943 FLIGHT 229

Jumo 211. The oil cooler and coolant radiators are built asfront of the engine in the Ju 88A.1 installation. The air flow is

JUNKERS JUMO 2HA ENGINE

an annulus at thecontrolled by gills.

Cooling

No. of cylindersDisposition of cylinders

Bore 150 mmCompression ratioSwept volumn (total)Direction of rotation, crankshaftDirection of rotation, airscrewAirscrew reduction gear typeAirscrew reduction gear ratioSupercharger typeSupercharger drive ...

Supercharger gear ratios •Weights, Engine and main engine

parts. Engine, oily before strip-ping, with fuel pump, magnetosand airscrew shaft and sparkingplugs ...

Weight of engine mounting, com-prising two magnesium forgings,tubular struts, ball ends and attach-ment plates for engine

liquid 40 per cent. Glysantin, 60per cent, water.

12Inverted 60 deg. Vee; 6 cylinders

in line.Stroke 165 mm.6.57 to 1.35.1 litres (2140 cu. ins.).Left hand.Right hand.Spur gear.SI to 20.Centrifugal.Bevel gear from crankshaft and

Ortlinghaus clutch two speed gear.1 to 7.95 and 1 to 11.375.

14531b.

96 Jb.

usual feature of this unit is the transverse mounting of thesupercharger, which is located by two dowels and fixedwith a single ring nut. The impeller is of the usual Junkersspout type of construction, and the diffuser is withoutvanes. The shaft is carried on hardened-steel bushes whichrotate in self-aligning aluminium-alloy bearings.

Unusual Scraper RingsThe two-speed gear is housed in the auxiliaries gear box

and is driven by a bevel gear, which is coupled by a splinedshaft to the crankshaft. Examination of the pistons revealthat they are of aluminium alloy, with slightly dishedcrowns ribbed on the inside. Three gas rings and twoscraper rings are fitted, one of the latter being above thegudgeon pin ; oil return holes are drilled behind and belowthese rings. As mentioned, the scraper rings are of unusualdesign, being chamtered on the combustion-chamber sideto approximately half-ring thickness. On the crankcaseside the ring is undercut with a vee groove arranged sothat a knife-edge is presented to the oil film on the outwardstroke (towards crankshaft) of the piston.

Both inlet and exhaust valves are of normal design andslightly recessed on the upper faces. Exhaust valves aresodium cooled in the stem and have " Stellited " laces, andare made of austenitic steel. Inlet valves have 30 deg.seat, whilst exhaust valves have seats at 45 deg.„- Two springs are fitted to each valve, and calculationindicates maximum stresses in the inner and outer springsof 64,000 and 68,000 lb./sq. in. respectively. The unusualfeature of the taper cone cotters is that they are made inone piece, split at one side and grooved down the other.

The probable advantage of this designis that the spring load on the stem ismore evenly distributed with thesecotters than with the normal splitcotter.

A further unusual feature is to befound in the design of the crankshaft,in which all webs are in the lonn offlat plates and are extended to formbalance weights, the shape of the pairof webs on each side of each mainbearing being similar. The crank- .shaft receives a supply of lubricatingoil through a sleeve at the front end,and all bearings are lubricated throughholes drilled in the journals and crank-pins. Short tubes are fitted in eachoil hole, which, in addition to prevent •ing sludge entering the bearing, maybe intended to act as bushes to reducethe stresses in the shaft around theholes.

Apart from the items mentioned,the design follows more or less estab-lished practice; the castings are ol

high quality throughout, several being of magnesium alloy,and all parts are well made and highly finished. The weightof the engine is low in proportion to the swept volume,1,450 lb. and 35 litres respectively, but on account of therelatively low maximum engine speed the power outputper litre is also low. Fuel oil, coolant, hydraulic and ahpipes are individually marked in accordance with a colou;code, and bulkhead connections are numbered to assistinstallation.

Forged Engine MountingThe engine mounting, of typical German design, con-

sists of two single-piece magnesium alloy forgings attachedto the engine at two points on each side and supportedby a steel tubular strut under each rear point of attach-ment.

Bearer plates are bolted and dowelled to the sides of theengine crankcase, and connected to the cantilever mountingthrough flexible rubber bushes

The mounting is attached to the nacelle by four " union "type nuts, thus rendering removal of the engine, completewith mounting, extremely easy.

The engine and oil cooling systems do not call for anyspecial comment, and in view of the full description alreadygiven in a previous issue of Flight relating to the directfuel-injection system this need not be referred to againhere. The description so lar relates to an examination olthe Jumo 211A as installed in the Heinkel He I I I H aircraft

Following the strip examination of the above enginesuperficial examinations of the Jumo 211A (3) and 211D (1)engines have been made and, in addition, the Jumo211B (1) type, as installed in the Junkers JU88A.I aircraft. Certain modifications have been embodied in thelater series which are summarised in the table, with corre-sponding details of the original 211A (1) engine. Such.

JUMO 211A SUPERCHARGER

Data at maximum engine speed of 2300 r.p.m.—Impeller tip speed in high gear (11.375 x crankshaft

speed) 1080 ft./sec.Impeller tip speed in low gear (7.95 x crankshaft speed) ... 746 ft./sec.Number of impeller spouts . 14Total flow area at impeller tip . 13.02 sq. in.Total flow area at impeller eye ... .. ... 18.8 sq. in.Impeller tip diameter ... .. 9.45 ins.Entry guide blade tip diameter . .. 5:79 ins.Entry guide blade root diameter 2.86 ins.Under take-off conditions (1200 b.h.p., 2300 r.p.m.):—Axial velocity at eye 176 ft./scc.Velocity of entry guide blades at mean diameter ... • ... 322 ft./sec.Angle of entry guide blades to tangential direction at me an

diameter:—Theoretical . .. ... . .. 29 deg.Measured 81 deg. ± 3 deg.

Estimated maximum pressure ratio at ground level, 2300r.p.m. in high gear is between 2.0 to 1 and 2.1 to 1.

Area of mouth of air intake (gross) .. . - ... S2.0 sq. in.

Page 3: Junkers 211.pdf

23° FLIGHT AyGUST 2 6 T H , 1943

T H E J U N K E R SJ U M O 211 SERIES

modifications have been designedprimarily to overcome operationalfaults and to improve control, but inthe case ot the 21 ID (I) engine it willbe noted the maximum crankshaftspeed has been increased.

It is interesting to note also thatfuel recovered from the first twoengine installations was of 88 octane.That Irom the 2riD (1), on the otherhand, was a high-quality spirit of 91.5octane.

The 211B (1) series engines examinedfrom the Ju 88A.I aircraft* are, ingeneral, similar to the 211 A type pre-viously described. Modifications tothe installation in this aircraft, how-ever, differ considerably from theHeinkel I I I H .

New Modifications

A brief summary of these modifica-tions is as follows: —

A barometric capsule-operatedautomatic two-speed gear change isfitted to the supercharger to engagelow gear below about 10,oooft. Thismodification prevents, by overridingthe pilot's control, the use of the high-speed gear below asafe altitude. The injection-pump fuel-control limit isfitted with a second capsule to correct the fuel deliveryfor varying exhaust back pressures, and so maintain amore consistent mixture strength.

The oil cooler and coolant radiators are built as anannulus round the header tank at the front of the engine,the cooling air flow being controlled by gills operated bycrank and sprocket mechanism attached to each and drivenby an endless chain from a small high-speed (14,000 r.p.m.for 15 seconds) Siemens motor controlled by the pilot. Thisprovides an extremely compact installation, dispensing withthe hydraulically operated retracting radiator as fitted inthe Heinkel I I I H aircraft.

Electrically driven immersed pumps are fitted in thefuel tanks, and jettisoning is effected by use of the super-chargers, while de-icing of the wing leading-edges is pro-

8UMMARY OF MODIFICATIONS TO LATER TYPES.

Detail

R.P.M.Max. for peakpower as indi-cated on enginedata plate

Fuel : octane No.referred to C.F.R.engine

De-aerator

Injection pumpcontrols

Magnetos

Supercharger

Oil cooler

Injection pump

211A (1) engine

2,2(X)

88

Fitted on rear of engine

One Bowden type cable forslow running mixture ad-justment wired immovablyafter setting to fixed throt-tle back-plate, and con-nected on pump to the mix-ture control worm spindle

Two Bosch Type GE.12.BRS.with booster coil and auxi-liary retard contact breaker

Centrifugal, with two-speedgear with hand operatedmechanical change gearmechanism. Ratios :•—11.375 and 7.95

Honeycomb

Junkers 12 cyl, V Type

Modifications.

I l l A (3) engine

2.200

88

Fitted on injection pumpand considerably modi-fied

One Bowden type cablewired to throttle as in211A(1). Asecond cablefrom worm spindle in-terconnects with fuelfilter selector

Similar to 211A (1)

Similar to 2 1 1 A (1)

Similar to 2 1 1 A (1)

Similar to 2 1 1 A (1) butwith plunger stroke in-creased by Q.OlOin.

211D (1) engine

2,400

91.5 .

Similar to 2 1 1 A (3)

Similar to 2 1 1 A (3)

Similar to 2 1 1 A (1), butwith the retarded contactbreaker automaticallybronght into action alsoon slow running

Similar to 2 1 1 A (1) but withchange speed mechanisjfihand operated throu •*£*-.hydraulic servo &f

Similar to 2 1 1 A (1) but withlarger capacity

Similar to 211A (3) but withcontrol unit modified forback pressure correction

,JUMO 211 B . I W E I G H T A N A L Y S I S

As Insta l led in J u 88A.I Aircraft

1b. oz.Engine only, with main engine parts, airscrew shaft and

plugs, etc 1605 14Exhaust manifold (port) 33 0Exhaust manifold and boiler (starboard) 39 12Exhaust manifold cowling ... 30 0Engine bearers (2) ... ... 90 0Coolant header tank ... ... ... ... ... .... 15 0Coolant radiator and oil cooler assembly 280 0Cowling for radiator assembly ... 24 0Gill assembly (incomplete by approx. 20 per cent, by

weight) 77 8Starter, generator, booster coil, V.P. airscrew motor elec-

trical services junction box, electric leads, etc, 05 8Vacuum pump 4 0Hydraulic p.iiup 5 fi

Total weight 2300

Supercharger. Details of the supercharger. The impeller is of the usual Junkersspout-type construction.

vided by heat from the exhaust sys-tem. -Improved types of hydraulicand vacuum pumps are fitted, thelatter operating Goodrich-type de-icing bags on the tailplane.

The same high standard of work-manship and attention to detail shownin the previous engines examined isapparent in the 211B (1), but thecompact installation would requireskilful planning for quick production,and certain of the controls are by nomeans conveniently situated.

Data relating to the engine, super-charger and also the weight analysisfor the complete installation on theJU88A.I are given in the accompany-ing tables.

In a description of the engine inFlight of November 16th, 1939, it wasstated that width and length -areabout 8oin. and 67m. respectively,and in general design the engine re-sembled the Jumo 210. At the timeit was known that at 13,800ft. a

Page 4: Junkers 211.pdf

AUGUST 26TTI, IQ43 FLIGHT 231

maximum power of 975 h.p. was available forfive minutes at 2,300 r.p.m., and that theJunkers company quoted a power of 1,200 h.p.for the then latest Jumo 211, which un-doubtedly was a take-off rating.

I t may be recalled that, as recorded in ourarticle in the August 5th issue, the bench testscarried out on behalf of the Ministry of Air-craft Production indicated a maximum take-off power, for the 211D, of 1,160 b.h.p. at2,400 r.p.m., and 4.7 lb./sq. in. boost.

Crankshaft. All webs are in the form of flat plates and extended toform balance weights.

Aeronautical Technical TrainingQrowitig Support for Improved Facilities

rHE keen interest that Flight and its associatedmonthly journal, Aircraft Production, have con-sistently taken in pressing for an extension of the

facilities available for the advanced technical training ofaircraft engineers is well known. Improved and widerresearch facilities, larger modern wind tunnels, and studyt^gj works production technique have been among ouraims. The idea of a national university of aeronauticsfor post-graduate students was discussed in these columnsearly in the year, and national publicity was accorded to

'the project as a result of a letter to the Daily Telegraphon May 7th from- the Managing Editor of Flight, whoextended a proposal advanced by Mr. F . G. Miles. Sincethat time a great deal of influential support for the cam-paign has been forthcoming, and a further letter, whichappeared in the Daily Telegraph on Friday, August 20th,briefly reviews progress achieved. A copy of the letter isappended:—

Sir,—On May 7th you published a letter from me in whichthe possibility of the Government sponsoring a NationalUniversity of Aeronautics was broached, and you supportedthe plea in a leading article.

In the letter it was stressed that the dearth of facilitiesavailable to aspirants for technical positions in aircraftengineering and for specialised technical education in thescience of aeronautics was a serious educational deficiency,

I to. which problem Mr. F. G. Miles had drawn attention. Theburden of the plea was to bring under one roof all thesciences and branches of engineering and technology directlyor indirectly connected with aircraft problems.

Correspondence followed my letter, and it seemed to beacknowledged that chairs of aviation at three universitieswere not enough in view of the importance of the subjectto our future national well-being. Subsequently the RoyalAeronautical Society arranged two public discussions (which,by the way, were well attended). Many interesting .viewswere put forward by the leaders in the industry, by educa-tional authorities and by students and associates, and thecommon view emerged that a central institution for thetraining of aeronautical engineers would go a long waytowards meeting a real need.

Not all are agreed, however, that a separate University

of Aeronautics is called for, though it does seem to be fairlygenerally agreed that post-graduate students need lavishresearch facilities and access particularly to larger windtunnels to cope with the enlarged size of modern aircraft.There is agreement also, as urged in my original letter, thatproduction techniques should form part of aeronauticaltraining.

As a result of this campaign and its powerful reinforce-ment in the House of Lords last month by the Earl ofListowel, who drew attention to notes on the subject by theSociety of British Aircraft Constructors, the Paymaster-General, Lord Cherwell, announced a move on the part ofthe Government.

They had asked the Aeronautical Research Committee toexplore the possibility of founding a school of aeronauticalscience, which would have a convenient airfield, with all theequipment and facilities involved, and close enough to oneof the great existing research centres for students to beassociated with work requiring the most elaborate equipmentin the country. The school was to be as free from bureau-cratic control as were the universities, and it was hoped toexplore, with the Governments of the Commonwealth andthe Empire, the possibility of making the proposed institu-tion a great Imperial venture.

The result of the deliberations of the Aeronautical ResearchCommittee is not yet available, but the report of the SelectCommittee on National Expenditure (Aircraft Production),before which I had the honour of laying evidence, surelyconstitutes a timely cue for immediate Government action.

This White Paper emphasises the acute shortage ofscientific and technical personnel and relates the dearth tothe entire industry, including existing official establishmentsand the whole field of aeronautical research. No morestriking confirmation of the situation it is sought to remedyhas yet appeared.—Yours faithfully,

G. GEOFFREY SMITH,Managing Editor of Flight.

Dorset House, S.E.i.

"FLIGHT" INDEXCopies of the index to Flight, January to June, 1943, will be

ready shortly, price is., or by post is. i |d . With cloth bindingcases 4s. 6d. and 4s. i.id. respectively.

BOOK REVIEW"Lathe Work"—A Practical H/znd Book for Lathe Operators.

AT the present time when large numbers of new people, bothmale and female, are entering the engineering industry,

their training becomes a serious problem. To become efficientoperators this unskilled labour requires more tuition than thatnormally given in the workshop, as this usually consists onlyof instruction in one particular job. One solution to this diffi-culty lies in encouragement to read suitable technical litera-ture, but, unfortunately, it is rather difficult to find books ofa sufficiently elementary nature for this type of person.

Appreciating this, Saunders Roe, Ltd., produced a pocketsize reference book for the use of their lathe operators. It iswritten in simple language and well illustrated with explanatorysketches. The various parts of different types of lathes aredescribed in a detailed manner, and many "do's and don'ts "hints are given. Chucks, centres, steadies, tools, screwingheads, sketches and measuring instruments are covered, and

the turning of a typical job in each type of lathe is describedin detail. At the back of the book is a dictionary of unfamiliartechnical words and also several pages of useful data. TheParliamentary Secretary to the Ministry of Aircraft Produc-tion and Sir Wilfrid Rhodes Freeman, K.C.B., C.B., D.S.O.,M.C., have stated their approval of this book, and the M.A.P.have brought it to the notice of certain of their contractors.

In view of the success of this book in their own factories.Saunders Roe, Ltd., have decided to make it available to otherengineering firms, and have agreed to forfeit all copyright feesfrom the sale of the book in favour of the R.A.F. BenevolentFund. The price of the book is governed by the quantityordered, e.g., stiff bound copies ordered in minimum quantitiesof 1,000 copies cost 2s. 3d. Orders for more than 100 butless than 1.000 can be supplied with the purchaser's name onthe cover at slightly extra cost. Details can be obtained fromThe Press at Coombelands, Ltd., Addlestone, Surrey.


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