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JL McClellan: FW-190 draft Copyright 2005 p 1 of 36
Editors note:The Design Analysis article was originally
published in the October, 1944 issue, Volume 43,number 10, and the Gear Retracting Unit was in theMarch, 1945 issue, Volume 44, Number 3, of Aviationmagazine, published by McGrawHill PublishingCompany of New York, NY, USA. Supplementalillustrations are from the 1942 volume.
This reconstruction is derived from microfilm. Thesource is University Microfilms International,Publication No. 364 (Aviation Week and SpaceTechnology), Reel No. 18 (January 1942 – December1942), Reel No. 20 (January 1944 – December 1944)and Reel No. 21 (January 1945 – December 1945). Thesource was from tightly bound volumes, so that there issome distortion of the images, especially near thebinding. It has not been practical to remove orcompensate for all the distortions, so none of theillustrations in this reconstruction should be consideredreliable sources as to fine details of shape, proportion orspatial relationship. The distortions are, in general,small, and should not detract from a generalappreciation of arrangement and relationship.
The editor has attempted to represent the originallayout of the article, but there are some exceptions.Limitations in the compositing tools cause a differencein the text flow relative to the illustrations, compared tothe original, so that some changes have been made, tocompensate partially for that effect. Tabular informationhas been consolidated at the end of the article, and an
enlarged copy of the cockpit instrument panel layout hasbeen added at the end of the article.
The Design Analysis article was one in a series ofdesign analyses published in Aviation during the waryears, between May 1943 and November 1945. Thesubjects were the Bell P39 Airacobra, Curtis C46Commando, Fleetwing BT12, Douglas A20 Havoc,Bristol Beaufighter (British), deHavilland Mosquito(British), North American P51 Mustang, Lockheed P38 Lightning, FockeWulf FW190 (captured German),Boeing B17 Flying Fortress, North American B25Mitchell (specifically, the B25H and B25J models),Mitsubishi “Zeke 32” Hamp (captured Japanese),Consolidated Vultee B24 Liberator, Fairchild C82Packet, and Messerschmitt Me262 (captured German),with one article dealing specifically with the Me262'sJumo 004 jet engine. Some of the analyses wereauthored by senior members of the design teams at theoriginal manufacturers, while others were written bystaff editors of Aviation magazine.
The original articles were copyright to theirrespective sources: the employers of the authors,following general practice of the time.
This reconstruction is compilation copyright JLMcClellan, 2005.
JL McClellan: FW-190 draft Copyright 2005 p 2 of 36
DESIGN ANALYSIS NO. 9
THE FOCKE-WULF 190
By JOHN FOSTER, Jr., Managing Editor, Aviation, and
CHESTER S. RICKER, Detroit Editor, Aviation, who also drew the field sketches.
Here is the most comprehensive engineering report ever published
on the Luftwaffe's top-ranking fighter, revealing for the first time
many structural features and Nazi design theories. Presented with
AVIATION'S inimitable wealth of detail and on-the-spot sketches.
ERMANY'S FOCKEWULF 190presents an apparentlystrange combination of
simple, yet sturdy, construction,paralleled by highly complexcomponents. Analysis of the craftreveals, however, that is has beendesigned for the pilot and the fieldmaintenance man. What oftenappears initially to be anunnecessarily complex small unitturns out to be a welldesigned, selfcontained, and quickly removablecomponent.
G
Underlying theory of the entiredesign appears to be to reduce fieldmaintenance time to a minimum, asthough the plane had been createdwith the idea that it's quicker to getparts off the plane replaced than torepair the parts themselves.
Then, too, the design is such thatthe craft can be built throughwidespread use of subcontracting ordispersal plants. The fuselage, forexample, is comprised of two majorcomponents, the fore sectionextending from the firewall, or whatthe Germans call bulkhead No, 1, tobulkhead No. 8 aft of the pilot's seat,and the aft section extending frombulkhead 8 to the empennage.
The fore fuselage section is theheart of the plane and is, in effect, adoubledeck box type structure, withthe top section making up the pilot'scockpit and the lower sectionserving as the fuel tank bays.
The firewall, or No, 1 bulkhead, isbuilt up of light sheet steel backedby sheet aluminum alloy riveted tobuiltup flanges extending from thetwo top forged engine mount fittingsdown to forged fittings which serveas attaching points for both lowerside engine mounts and the frontwing spar.
Longerons run aft from these fourpoints to No. 8 bulkhead, where theyare spliced to lighter ones in the aftsection. Top longerons are 13/4 in.wide Usections made up of 3/16in.thick aluminum alloy and serve astracks in which the cockpit canopytravels. One hatshaped stringer oneach side, 101/2 in. below the toplongerons, make up the onlyhorizontal stiffeners in the top partof the fuselage. Aluminum alloysheet, riveted to the lower longerons,forms the cockpit floor, separating itfrom the fuel tank bays.
Bulkheads in the upper forefuselage section are not uniformly
JL McClellan: FW-190 draft Copyright 2005 p 3 of 36
ACKNOWLEDGEMENTThe editors of Aviation are deeply grateful to Brig. Gen. K. B. Wolfe, Commanding
General of the Army Air Forces Materiel Command and members of his staff forassistance in preparation of this article.
For unstinting cooperation and help, special thanks to: Major D. L. Hancock, Lt. J. E.Arnoult and Mr. M Llacera of the Technical Data Laboratory; Capt. Howard M. Spickler,chief, and Lts. Joseph Becker, W.H. Wilson and A. J. Shank of the Captured EquipmentUnit, AC/AS, Int. W.D.C. And Lt.Col. G. R. Johnston, Chief, Public Relations Section andMr. D. P. Kelly.
spaced, nor are they all of the sameconstruction. No, 2, of conventionalstamped flanged construction, is 121/2 in. aft of No. 1; No. 3 some 65/8 in. farther aft is directly beneaththe front windshield base. No. 4,also of conventional construction, is105/8 in. farther aft. No, 5, directlyunder the rear end of the fixedwindshield and above the rear sparfitting, is angle shaped against theskin, and extends above the flooronly to the stringer. It is braced by a3/4in. tubular section flattened ateach end for riveting to the bulkheadand cockpit floor. No. 6 is an Aframe structure, the base of the forepart being 12 in. aft of the No. 1 5bulkhead, the top 181/2 in. fartheraft. The sloping fore part is achannel section in which the pilot'sadjustable seat is supported. Thevertical member, set 5 in. aft of thetop,is conventional stamped, flangedconstruction, riveted to the fore partat the top by a web plate ofaluminum alloy. No. 7 isconventional construction, set 12 in.aft of the rear part of No. 6, and No.8 is a builtup stamped flangedmember extending the full depth ofthe fuselage, and forms the joiningpoint of fore and aft fuselagesections.
The lower fore fuselage, or fuel
JL McClellan: FW-190 draft Copyright 2005 p 4 of 36
Fore and aft sections of fuselage. Fore section, which is heart of plane,extends from firewall aft to bulkhead No. 8, which is shown in detail A.This section is divided into upper and lower sections, separated bycockpit floor, which is indicated by dotted lines 1. Lower sectioncontains fuel tank bays which are covered by single skin panel 2. Thisis quickly detachable by loosening nine screws along each side and fivein each end. Rear spar fuselage attachment fitting is shown at 3.
Details of fore fuselage section between firewall-bulkhead No. 1 and bulkhead No.8,with top longerons cut away. This detail shows how bulkheads are unevenly spacedand vary in construction. Forged rear spar attachment fitting, shown in detail drawing,is attached to build-up web tie-through member, which also serves to separate two fueltanks
bay section, has but six bulkheads. No. 1 forms the front end, being
JL McClellan: FW-190 draft Copyright 2005 p 5 of 36
Cut-away view of aft fuselage section, from point where it is attached tofore section by double row rivets, aft to bulkhead No. 14, where empennageis bolted to it. Bulkheads 9 and 10 are built up in three sections, rivetedtogether. Tops of bottom sections are flat to accommodate camerainstallations. Fabric panel in set in No. 12 to prevent dust from seepingforward into fuselage. Tube mounted in No. 13 provides for lifting bar.
FW-190 fuselage with cockpit canopy,fairings and doors in place. “Waffle” typeconstruction, in which two skins are rivetedtogether by one rivet in each dimple, bringscowling weight to about 1.75 lb. per sq. ft.(compared with 1.25 for American andBritish cowling's), but reflect German designphilosophy of keeping fairings attached andin place for hurried locking. Fairings hingedat bottom of engine mount, giving access toaccessory compartment, serve as workstands. Top fairing, seen folded back overwindshield, covers two 7.9-mm. Machineguns firing through propeller arc; those justaft of engine-mount cowlings give access toinboard gun ammunition boxes. Door in aftfuselage gives access to radio, camera, andcompass.
right aft of the front wing spar. No.2, which is in reality a contour rib, is10 in. aft and is a continuation ofNo. 3 from the upper section.Lower No. 3, set 578 in. farther aft,is also a contour rib and joins thelongeron between Nos. 3 and 4 ofthe upper section. No, 4, of builtupweb construction, is the tiethroughmember between rear spar fittings,and separates the two fuel tank bays.No. 5 is set below the forepart of theAframe No. 6 of the upper sectionand, like lower No. 6, which is set11 in. aft, is contourrib type.
One belly skin panel, attached tolongitudinal and transverse angleshaped stiffeners, is attached to thelower fuselage section by ninescrews along each side and five oneach end, thus giving quick access tothe two self sealing fuel tanks,which are suspended from thecontour ribbulkheads by heavy webstraps.
On the upper fore fuselagesection, immediately aft of the topengine mount fittings, the fuselagestructure is flat, forming a shelf towhich are bolted mounts for the twin7.9 mm. machine guns that firethrough the propeller. Back of thisgun mount shelf the fuselage sidesextend up to form the base for thewindshield, the front panel of whichis 13/4 in. bulletproof glass.
At the base of this front panel ishinged the fairing to cover the guns
JL McClellan: FW-190 draft Copyright 2005 p 6 of 36
Field sketch showing details of heavy toggle latches which hold cowlingand fairing in place. They are strong enough to spring fairing into placeeven if it is distorted. Tension adjustment, with small flat bar lock, isshown at left. Center sketch shows toggle in closed position, and slot inmating piece is at right. Sketches at upper right reveal details of lock.Locking plate has two depth slots, so center indicator pin sticks up whenlatch is unlocked; it is flush when locked.
Heavy toggles are also used on engine cowling, this sketch showingthem at top. Piano-type hinges, with eye for easy removal andinspection, are used at bottom.
Three adjustable air outlet flaps, mounted in doors hinged at bottom, are set on eachside of engine cowling. To operate them, a screw-and-nut mechanism is attached toforward side of firewall and is connected to each side door by tubes. Latter areconnected to linkage on doors by levers and bell cranks so arranged that they do nothave to be removed or adjusted when doors are opened..
just mentioned. This fairing, whichhinges up and back for access to theguns, is of “waffle” typeconstruction, with the two skinsbeing fastened together by one rivet
in each inner skin dimple. Threeheavy locking toggle switches –typical of those installedthroughout the plane – are used oneach side to hold the fairing in
place.Such heavy cowling – and easily
removable hinges to keep it in place– naturally adds what seemsunnecessary weight. It is, however,in keeping with the apparent designtheory; the cowling is always on thecraft ready for locking and a quicktakeoff. It is heavy enough to standhard wear, in fact, the side panelsswinging downward around theengine mount are used as workplatforms. Too, in case the cowlingis bent a bit, the toggles are sturdyenough to pull it into place for quicklocking.
Cowling on the FW190 averagesabout 1.75 lb. per sq. ft., comparedwith 1.25 for British and Americancraft, but the German's persistent useof the type indicates their belief thebeatings it can take and the speedwith which it can be locked in placemake it worth the added weight.
The cockpit cover and its fairingare built as an integral unit. Base ofthe structure is a 5/8in. tubularmember bent into an inverted U atthe front to fit into the windshield.The plastic glass of the cover ismounted between two strips of bunaand a flat aluminum strip, held byscrews driven into selflocking nutsin the tube. At the rear of the plasticglass a stamped, flanged aluminumAframe sets between the tubeframeends, and is riveted to aluminumalloy fairing mounted on a 3/4in.tube extending aft. The wholestructure rides on three ball bearingrollers; one on each side at the frontof the plastic glass section in the topfuselage longerons, and one attachedto the tube, running in a channelsection (which serves as top
JL McClellan: FW-190 draft Copyright 2005 p 7 of 36
DIAGRAMMATIC COCKPIT LAYOUT
Cockpit canopy details, showing method of fastening plastic glassto tubular frame. Entire canopy slides on ball bearing rollers intracks formed by upper fore fuselage longerons and in trackformed by upper aft fuselage longerons. Canopy can be operated
only from inside cockpit, by crank on right side attached tosprocket engaging pin ratchet (seen at left above) attached to frontend of tubular frame. Note silhouette armor plate mounted incanopy frame; it slides forward to just behind pilot's head.
longeron) set in the fuselage turtledeck.
The cockpit cover can be operatedonly from inside by a crank attachedto a sprocket which engages a pinratchet attached to the front end ofthe tubular frame. Emergency exitcan be effected by pushing down ona small handle located near thecrank. This disengages the sprocketand then, through a series of rodsand shafts, releases a latch holdingthe firing pin. A cartridge explodesand blows the rear end of the canopybackward far enough to let the slipstream get under and pull it away.The explosive charge – about thesize of a 12gage shotgun shell – islocated aft of a silhouette of 1/4 in.armor plate back of the pilot's head.This armor is attached to the cockpitcover tubular member by linksattached to studs welded to thearmor plate.
An interesting angle of the cockpitcover is its connection with the radioantenna, which leads in from thevertical fin to and over a pulley setin the plastic glass just behind thearmor plate, then over another pulleyset in the aft end of the cover fairing,then forward again to an insulatedleadin to the radio mounted justbehind No. 8 bulkhead. Thus,regardless of whether the cockpitcover is open or closed, the radioantenna has the same tension.
While the cockpit itself does notgive the appearance of beingovercrowded there is, nevertheless,no waste space. Flight and engineinstruments are arranged on twopanels beneath the windshield andon horizontal panels on each side, asshown in the accompanyingdiagrammatic layout. The pilot'sseat, the back of which is made ofarmor plate, is only adjustable upand down 4in. and is designed forseat pack parachutes.
The aft fuselage – from bulkhead8 through 14 – is semimonocoqueconstruction, and is attached to thefore section by a double row ofrivets through both skins and theflanged section of bulkhead 8. Anexamination of several differentcraft, including more than onemodel, indicates these two sectionsare not jigdrilled prior to mating.Apparently the two sections arebrought together in a mating jig andboth drilling and riveting done there,for variations in rivet locations are
readily apparent. This same type ofassembly is rather widely used, aswill be noted in the discussion ofother components.
Bulkheads No, 9 and 10 of theaft fuselage section are built up inthree sections, the bottom onesbeing heavy channel sections withflat tops to support camerainstallations. Upper portions ofboth are conventional stampedflanged construction, rivetedtogether and to the bottom sections.
Numbers 11,12, and 13 are oflighter construction and followconventional practice, being builtin halves and riveted together at topbottom. No. 13 contains a crosstube for lifting the fuselage. In No.12 there is set a fabric panel tokeep dust from seeping forward tothe radio, camera and mastermagnetic compass with its contact
for control of the repeater on theinstrument panel.
Bulkhead No. 14 is heavy flangedconstruction for bolting theempennage to the aft section.
There are two upper side channelshaped longerons, riveted to thosefrom the fore fuselage by 6in.splices and they extend to aft ofbulkhead No. 11. A channelshapedtop longeron extends the full lengthof the aft section, between bulkheads8 and 11 serving to support thecockpit cover fairing track. Thereare six Zshaped stringers withrolled edges on each side of thissection of the fuselage and five inthe bottom in addition to two heavyUshaped stringers where side andbottom sections are joined.
The aft fuselage skin – like that inthe fore section – is slightly lighterthan our 24ST, but no evidence of
JL McClellan: FW-190 draft Copyright 2005 p 8 of 36
Here are details of mechanism which blows canopy away for emergency release.Mounted in aft tube (behind armor plate) which rolls in aft fuselage section top longeron,it is operated by lever at pilot's right hand. A safety (1) is provided in firing block.Explosive charge(2) looks like ordinary shotgun shell. Firing pin is shown at (3) andrelease at (4).
Accessories in Focke-Wulf 190 fuselage section. (1) Is hot air supply to cockpit; (2) iscover over fuel pumps and electric junction boxes; (3) is handle moving canopy; (4) isarmor and bulletproof glass; (5) is battery; (6) is explosive canopy release; (7) is cameramount; (8) step which telescopes up into fuselage; and (9) fabric panel in bulkhead No.12 to protect instruments located in aft fuselage section.
wrinkling was found in the severalcraft studied. Flush riveting is usedon every surface of the craft.
One of the outstanding examplesof simple, yet sturdy constructionfound in the FockeWulf 190 is theempennage. It is attached to the aftfuselage section at bulkhead 14 bymating, flanged bulkheads through aseries of closelyspaced bolts.
Leading aft from this bulkhead,some 5 in. form the top skin, is astamped flanged rib with lighteningholes, extending from side to sideand seven and three eighths incheslower is another fullwidth rib. Thestabilizer goes through the fuselagebetween these ribs.
Both ribs intersect a diagonalmember which is the heart of the
empennage, for it carries tail wheelloads on the ground and, once thecraft is airborne, carries both finandrudder and stabilizerandelevator loads.
Starting at the bottom skin 183/4in. aft of the attaching bulkhead, thismember extends up and aft 631/2in. to the top vertical fin rib (whichextends aft to support the top rudderhinge) at the base of the detachablevertical fin tip. Nine inches formthis member's lower end, on the aftside, is riveted a fitting to which isattached the front end of the tailwheel drag yoke. On the front face,between the two horizontal ribspreviously noted, is riveted a forgedhexagonal fitting to which thestabilizer rear spar attaches.
Above the top horizontal rib, onthe aft face is riveted a 20in. doublechannel member which forms theguide rails for the tail wheelretracting unit, which will bedetailed later. The channel memberis surmounted by a plate bearing apulley which is part of the retracting
JL McClellan: FW-190 draft Copyright 2005 p 9 of 36
Cut-away view (left) of empennage and integral vertical fin.This section bolts to aft fuselage section at bulkhead 14.Diagonal structural member is heart of this section, for itsupports tail wheel loads when craft is on ground andsupports fin, rudder, stabilizer, and elevator loads when shipis airborne. Two skins, extending from the bottom of fuselageto top horizontal rib at base of fin tip, are riveted together attop along a vertical flange. Aft of diagonal member and abovemiddle horizontal rib, skins are of “waffle” construction.
Hinged inspection door ─ 30 in. high by 15 in. across base –is locked in place by special screwdriver-operated fasteners.Piano hinge and springs are protected by fabric covering.Field sketch (above) gives detail of fin leading edge, showinghow two skins are riveted together along vertical flange.Single formed aluminum alloy fairing is fastened over flangeby flush screws driven int diamond-shaped safety nuts rivetedbetween flange. Same method is used for leading edge ofstabilizer.
Detail field sketch showing construction of door latches. Forged bracket A, is riveted todoor. Operating bell crank is made in two parts. Stop B, which limits throw; and latchpiece C, which drops into slot in bracket when locked. Latch is turned with screw driver atE. Spring keeps screw head flush when in locked position. It must be pressed inward torelease. Guide bracket D is soft enough so that it can be beat with pliers to tighten lock.
unit, and the top fin rib.The topmost of the two horizontal
ribs extends aft of the diagonalmember 161/4 in., the middlerudder hinge being mounted at itsend. The other horizontal rib, aft ofthe diagonal, extends downward atapproximately 28 deg. from the baseof the stabilizer fitting to the bottomof the tail cone to support the lowerrudder hinge. A vertical web plateof stamped flanged alloy connectsthe two ribs at their aft ends.
Below the two horizontal ribs,three Zshaped stringers on eachside run from bulkhead 14 to thediagonal member, and a similarnumber are employed above.
At the leading edge of the fin, theskin is crimped and riveted together,with a series of 5 diamondshaped,self locking nuts inserted and rivetedbetween the crimping. The leadingedge skin, a single sheet of formedaluminum alloy, can then befastened in place with flush flat headscrews driven into the diamondnuts.Drilling of the two fin skin surfacesapparently is not a jig operation, forstudy of several craft showeduneven spacing and lack of rivetalignment. In one plane, as a matterof fact, even a difference in rivetsizes was evident.
Skin aft of the diagonal member –between it and rudder hinge points –is of the familiar double skin“waffle” construction, eliminatingthe need for stringers. A triangularinspection door – 30 in. high by 15in. across the base set in the left sideof the fin gives quick access to thetail wheel retracting unit and top ofthe oleo shock strut. Two screwdriven locks are used. The pianohinge springs to keep the doorclosed. These and the hinge aresealed in fabric.
Apparently deterioration of pilotquality, wellprepared airports, orsome other causes have resulted infailures in the empennage, forexamination of later models of the190 reveals that additional webplates have been installed betweenthe horizontal ribs behind and belowthe stabilizer fitting to betterdistribute the stabilizerelevator andtail wheel loads.
The dynamic and mass balancedrudder is built around a single sparof stamped flanged aluminum towhich are riveted the three hingefittings. Leading edge is flush
riveted to the spar, and ribs haverounded gusset plates. Trailingedge is also of metal, with theentire unit being fabric covered.Unlike most modern fighters, the190's rudder trim tab is adjustableonly on the ground. It consistssimply of a 15 x 1 in. metal stripriveted into the trailing edge, with aseries of perforations to facilitatebending to the desired degree.Two types of tabs are used; somewith slotted perforations, some
with round holes.The stabilizer is full cantilever
single spar allmetal construction,built as one unit except fordetachable tips. There are sevenfloating ribs on each side. Stabilizerattaches at the aft edge to thediagonal member of the fin throughforged fitting previously noted, andhinges on pins that go into selfaligning trunnions, for vertical trimof craft is effected through adjustingthe stabilizer.
JL McClellan: FW-190 draft Copyright 2005 p 10 of 36
Fabric-covered rudder is built around single spar (shown in detail at right). Top, center,and bottom bearings are shown in details at left. Rudder operating cables are attachedto outer holes shown in middle bearing detail. Note how hinge pins are tapered tofacilitate assembly. Rudder is secured by bolt on lower hinge pin. Trim tab is adjustableonly on ground. It consists simply of 15 x 1-in. Metal strip riveted into trailing edge, withrow of perforations to facilitate bending to desired angle.
JL McClellan: FW-190 draft Copyright 2005 p 11 of 36
Focke-Wulf 190 stabilizer is single-spar full cantilever structure built in two halves andbolted together at center line. Top and bottom skins are flanged and riveted together toform front spar. Leading edge is attached like fairing on vertical fin. Three ball bearingsupports for elevators are provided on each side (shown in detail in sketches at top).Formed tips are screwed into place with flat-head screws in countersunk washers.Captured nuts in flange of outer rib hold them in place.
Stabilizer angle of attack is adjusted by electric motor-driven screw jack mounted inleading edge of vertical fin, with hinge point along spar at trailing edge. Electric indicatoris attached to stabilizer so that its position is shown on instrument panel. This fieldsketch shows adjustment marks on fuselage and fairing.
Elevators are built around single spar(shown in center) with metal leading edge,ribs, and trailing edge. Whole unit is fabriccovered, fabric being stitched in place withwire loops. Even though stabilizer isadjustable in flight, right elevator (shownhere) has perforated trailing edge trim tab –adjustable only on ground – similar to thatfound on rudder.
Stabilizer adjusting unit, with ball-and-socketat top for attaching to inside of fin leadingedge and fitting at bottom for attaching tostabilizer. Electric motor runs at 14,000 rpm.And, through six gear trains with 533-to-1reduction gear, moves stabilizer over fulladjustment arc in about 20 sec. Magneticbrake keeps it from over-running whencurrent is turned off. Bellows type rubbersleeve at bottom of screw jack keeps itclean.
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Full cantilever wing on Focke-Wulf 190 is built around frontspar, which extends through plane from tip to tip just belowfirewall. It carries bottom engine mount support, shown herein detail sketch. Inner section of leading edge is built asseparate unit having its own ribs. Outer section, withconventional D-type ribs, is attached to lips extending outfrom front spar by flush screws
Front spar at center line is 16¾ in. deep, with triple web construction extendingout beyond inboard gun ports and double web to point beyond outboard bunports, from which point it is conventional single web I-beam. Lower skin, withribs, stringers, and inspection panels, is made up as separate subassembly andattached as unit to spar. Joggle in spar is deep enough so that landing gearwheel is in front of it when retracted.
On the center of the stabilizer'sleading edge is a fitting attached to ayoke which, in turn, fastens to ascrew jack and electric motorsuspended by a ball and socket jointfrom the leading edge of the verticalfin. This motor, which turns up to14,000 rpm., has six trains of gearswith 533 to 1 reduction. It movesthe stabilizer leading edge 4.1 in. permin., or over the full arc ofadjustment in about 20 sec. Amagnetic brake is provided toprevent motor overrunning whencurrent is cut off.
In the stabilizer, as in the leadingedge of the vertical fin, the upperand lower skins are crimped andriveted together and the leadingedge screwed in place via six of thediamondshaped nuts. In this unit,too, rivet alignment and spacing areboth irregular along the crimpedskin.
Elevators, like the rudder,generally follow conventionalpractice with a single spar, metalleading edge, metal ribs with thefamiliar rounded gusset plates,metal trailing edge and fabric
covering. Despite the fact that thestabilizer is adjustable, the rightelevator has a perforated trailingedge trim tab like that on the rudder.
The elevator hinges to thestabilizer at three points and,although all three fittings aredifferent, each hinge has an selfaligning ball bearing unit.
A departure from conventionalconstruction shows up in the 190wing, for it is built as a single unitfrom tip to tip. Thus, if it isdamaged structurally any placebetween the detachable tips, theentire unit, rather than say, onepanel, must be replaced.
The integral center section of thetapering front spar is a very heavymember, for it takes the weight ofthe two lower side and bottomengine mounts, fuselage fittingattachments, four 20mm. cannon,and main landing gear. At the centerline it is a builtup tripleweb Ibeam163/4 in. deep, reinforced by aheavy vertical channelshapedmember embracing, at its lower end,a forged fitting for the lower enginemount structure, a combined tubularandchannel truss unit. Between thecenter line and side engine mounts,set 24in. out, are two vertical hatshaped stiffeners. Engine mountmembers themselves are of similarshape, but are heavier and areriveted rather than bolted to the spar.
At these side engine mounts thespar is bent forward 14 deg., withthis angle being maintained 641/2in. to the main landing gear fittings,from which point it parallels thecenter section. The bend permits thelanding gear to retract in and upahead of the spar. This section ofthe spar has, in addition to thecannon ports, three lightning holesand three vertical angle stiffeners.
The tripleweb constructioncontinues beyond the bend to justoutboard of the port for the barrel ofthe inboard cannon. Immediatelyoutboard of the landing gear fittings,where the spar again bends, it is
JL McClellan: FW-190 draft Copyright 2005 p 13 of 36
Wing ribs of FW-190 vary in construction and only six are attached to both top andbottom skins. Top detail sketch A shows rib adjacent to fuselage, with reinforcementforgings; B is outboard-most “solid” rib; C and D are typical floating ribs; E is outboard ribto which formed tips are attached with flush screws. F illustrates construction of sparfrom outboard cannon port to wingtip, showing forward-extending lips, to which leadingedge is screwed.
reinforced by a heavy riveted gussetextending some 12 in. beyond theoutboard cannon port, from whichpoint to the tips the spar is singleweb Ibeam with 11/2 in. lighteningholes. For the full length of thisouter portion the spar has lips topand bottom to which th leading edgeis screwed.
The leading edge, form enginecowl outboard to the landing gear, isbuilt as one unit and is attached byscrews to the spar. The mainmember, just outboard of the gunport, is a double, stamped flangedrib with cutout for the landing gearstrut. Two feet farther out is anothercontour rib of Ibeam constructionand between them a stamped flangedcontour rib. Tipend of this sectionalso has a stamped flanged rib withcutout for the landing gear strut.Remainder of the leading edge isbuilt as one unit, consisting offormed aluminum sheet reinforcedby conventional stamped flanged Dtype nose ribs.
Only five 'tween spars ribs oneach side, besides those at thewingtips, are attached to both topand bottom skins. Of conventionalstamped, flanged construction, theyare located just outboard of theinboard cannon; on either side of thelanding gear fittings to form a torquebox; on either side of the outboardcannon ports; and at the outer end ofthe reinforcing gusset around theseports.
The rear spar, a conventionaltapering Ibeam, extends from topand bottom forged fuselageattachment fittings to the tips, andcarries both flaps and ailerons. It isdouble web for 32 in. from thefuselage fittings, single from there tothe tips.
It would appear that the rear sparand the top skin panel (forward tothe front spar) are built as an integral
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At top is shown inverted view of centralwing leading edge subassembly, withdetails of its major ribs given below.
Top skin, with its floating ribs and stringers,is made up as complete subassembly andriveted to rear spar and, finally, skin abovesplit-type flap with its ribs is attached torear of spar. Aileron brackets (shown in thedetail sketches) are also riveted to aft faceof rear spar. Note that space is left for thefew ribs fastening to both top and bottomskins; they are attached to this top skin byblind riveting.
JL McClellan: FW-190 draft Copyright 2005 p 15 of 36
Flaps are built around metal monospar andare constructed in two halves rivetedtogether at the middle hinge, with inclusionof actuating arm. This hinge – unlikeinboard and outboard hinges – is welded tospar and carries a dial with readings from 0-60 deg. Numbers show through a hole intop skin (as illustrated in top detail sketch)so that pilot has exact reading of eachflap's position at all times. Flaps areelectrically operated with their individualmotors connected through relay control boxso that neither will get more than 3 deg. Outof line with other.
This field sketch shows detail of flap fromabove, with top fabric covering removed toreveal how ribs are formed from cutoutsections of top face. Shown on trailingedge are two of ten rubber bumpers whichabsorb vibration when flap is closed upagainst top skin.
Complete details of aileron are shownbelow. From top to bottom: Unit withoutfabric covering; lower leading edge skin;unit with fittings and fabric covering inplace. At left is exploded view of inboardball-bearing mounting and at extreme rightis exploded view of outboard hinge slotribs.
JL McClellan: FW-190 draft Copyright 2005 p 16 of 36
Field sketch (right) of inboard end of aileronwith bottom fabric removed. Intercostals (but .012-in. Thick) only serve to hold fabric whichis stitched in place with continuous wirefastening poked through the slots punched inframe. These slots are in a groove so thatwire will be buried beneath fabric surface.Also clearly shown is perforated trim tab,similar to those used on rudder and elevator.
Main landing gear (below), showing howwheels are hinged from front spar. Retractinggear arms (1) and (2) are attached to electricmotor-driven drum (3) to which are attachedmechanical position indicator (4) and dash pot(5). Fairing (6) is pulled up into place whenlanding gear strikes arm (7). A steel cable (8)running from retracting gear arm in over pulleyat center line straightens arm (7) to holdfairing in open position when wheels aredown. Switch (9) between retracting geararms cuts power off when wheel s are down.When retracted, gear is secured by latchshown at bottom of detail sketch (10). Thisunit also carries switch to cut off power whenwheel is latched up. A cable attaches to lever(11) to release latch in case of power failure,when wheels go down by gravity as motor isdisconnected when power is off.
unit, with blind riveting beingnecessary only for attaching thefive topandbottom or “solid” ribspreviously mentioned, Threestamped, flanged contour ribs are
located between the “solid” ribs andsix are utilized between the outerflap hinge and the tip rib. All theseribs have cutouts for Zshapedspanwise stringers, of which thereare nine outboard of the flap, andeleven between the “solid” ribs. Skinaft of the rear spar, above the flap, isa separate subassembly attached byten contour ribs riveted to the sparweb, with one continuous stringerbetween the spar and trailing edge.
Also built as a unit is the bottomskin panel, which screws to frontand rear spars. One contour rib islocated at the fuselage attachmentfittings, one between the cannon andlanding gear ports, and five betweenthe outer “solid rib and the tips. Allthese ribs have diagonal cutouts forZshaped stringers similar to those inthe upper panel.
An interesting development foundon later 190 models is the additionof aluminum strips, .032in thick and3/4in. wide, riveted to the ribs andskin, much like diagonal bracesbetween joists in a house to preventside sway. This addition has beenmade to both top and bottom skin
JL McClellan: FW-190 draft Copyright 2005 p 17 of 36
Detail field sketch showing pressure indicating marks on main landing gear fairing.Lower part of vane moves with wheel; upper part is attached to oleo cylinder. Scale isgraduated in atmospheres, 25-30 being range.Phantom view from pilot's cockpit looking
toward leading edge of wing, showinglanding gear position indicator. It is entirelymechanical, like a bayonet oil gage. Itslides through slotted ball in top wing skinand disappears when landing gear is fullyretracted.
Main landing gear retracting motor and reduction gear, a unit but 14 in. long and 7 in. india. at ring, with bolt holes where it is attached to front t spar. Motor runs at 14,000rpm., has 3.3:1 reduction from armature shaft then safety centrifugal clutch, then 53:1and 60:1 gearless reductions for over-all reduction of 10,494:1. One such unit isprovided for each wheel.
JL McClellan: FW-190 draft Copyright 2005 p 18 of 36
Phantom view showing how tail wheel is automaticallyretracted with main gear. As right wheel moves up, it tightenscable A, which goes up over pulley, inboard to right side offuselage, then aft through conduit to vertical fin diagonalmember, up over it to pull up on yoke attached to top of oleo.As left wheel moves up it tightens cable B to open slidingdoor C under cameras.
Here is phantom view of vertical fin, showing tail wheelassembly. Wheel fork is set in front end of figure-eight castingto give castering action, but oleo strut is in direct line withwheel hub. Loads of both front end of drag yoke and top ofoleo strut are taken by diagonal member. Stabilizer goesbetween horizontal ribs extending aft from front bulkhead todiagonal member.
JL McClellan: FW-190 draft Copyright 2005 p 19 of 36
These field sketches show details of tail wheelretracting gear and roller locking device. Atleft is track (with oleo and lock removed)which is riveted to aft face of diagonalmember of assembly. Oleo would extend upthrough the dust-catching fabric with bellowattached to the top. Also shown is metal tubeto prevent coil spring from injuring enclosingmaterial. Sketch at right shows gear in placeand locked in down position, and in upperright method of locking is showndiagrammatically. A is direction of load thrust,B is direction of pull by coil spring. This pullstrigger roller C down into locking position,forcing large roller D – which takes landingload thrust from top of oleo – int its downposition.
Aileron control is via tube from control stick, leading forward to bell crank attachedto front face of front spar, then outboard through idler to compensate for 5-deg.dihedral, to point directly ahead of flap operating motors. Here bell crank changesdirection back to front face of rear spar, where direction is again outboard to bellcrank attached to aileron itself.
panels, and appears to be amodification made in productionrather than in the field.
Split type flaps followconventional practice, with themonospar being made up of a rolledsection with beaded stiffeners. Topskin section is cutout in the familiarrounded gusset pattern; ribs arenormal stamped flangedconstruction. Top and bottomsections are riveted together at theleading edge, and the whole fabriccovered. With a total span of 7 ft.10 in. each, the flaps are built up inhalves, the two sections beingriveted together adjacent to themiddle of three ball bearing hinges.Atop the trailing edge are ten 1/2in.dia. rubber bumpers to absorbvibration between the flap andtrailing edge.
Inboard and outboard hingefittings are castings riveted to theflap spar. The midfitting, whichalso forms the flap actuating arm, isof built up welded construction.Attached to this fitting is a dialreading 060 deg., visible through ahole in the top skin panel, so that thepilot can get an exact reading ofeach flap position.
Electrically driven by gear trainsthrough a nut to a screw jackattached to the motor mounted onthe front face of the rear spar, theflaps move down 60 deg. The twomotors are connected through arelay control box so that neither flapcan go more than 3 deg. withoutstopping to wait for the other tocatch up.
Fabriccovered Frisetype aileronsare as light in weigh as they arereported to be on controls. They arebuilt around a channel monosparwith beaded vertical stiffeners towhich are riveted upper and lowertwolayer metal leading edge skins,the inner ones having beadedstiffeners. Aft of the spar there are10 conventional ribs, with thefamiliar rounded gussets, and 10intercostals of stamped flanged lightaluminum alloy. These lightweightintercostals are provided to contourthe fabric and allow it to be stitcheddown with wire.
Ailerons are mounted on three selfaligning ball bearing hinges at ribsNo. 1, 5, and 9. The inboard hingeat rib No. 1 is a cast aluminumfitting into the bottom of whichscrews a lug and ball bearing collar,
running on a tapered pin assemblythrough the bracket attached to therear spar. The screw bearing collaris split and the taper jambs it tightwhen the lock nut is tightened.This makes it possible to getperfect alignment between thehinge, bracket and wing fairingwithout the necessity of matingparts in jigs. Mid and outboard
fittings are cast angle brackets, withroller bearing collar screwing infrom the bottom and running on apin through a bracket in the samemanner as the other hinge. In eachcase, curved shims between thebearing collar and bracket areutilized to eliminate side play whileretaining alignment. Balance weightwashers are fastened into the hinge
JL McClellan: FW-190 draft Copyright 2005 p 20 of 36
Phantom views showing rudder and elevator controls. Push-pull rods go direct fromrudder pedals to differential linkage located just ahead of bulkhead No. 14 in aftfuselage. From this linkage cables go inside vertical fin to ruder connecting points.Elevator controls go from stick via tube to right side of fuselage, then via push-pull rodto bulkhead No. 8, from which point two double cables lead back to differential unitlocated below stabilizer adjusting motor. Bell crank and push-pull rods lead fromdifferential to elevator horn. Both rudder and elevator differential units are shown in thedetail sketches.
JL McClellan: FW-190 draft Copyright 2005 p 21 of 36
slots with a bolt and captured nutriveted to each side rib of the slots.
On the inboard end of the rightaileron is a 1914inlong trim tab –adjustable only on the ground –similar to those on the stabilizer andrudder.
Main landing gear is a singlestrutoleo shock unit, with conventionaltorque scissors, attached to a forgedsteel tapered roller bearing spindleassembly. The front face of themounting is flanged to bolt to thefront spar. Fairing is in threesections; one attached to bracketsextending up from the hub, anotherbolted to the oleo strut and the thirdhinged at the center of the fuselage.A scale painted on the two fairingsattaches to the landing gear tells at aglance if proper pressure – about1,300 psi. is being maintained inthe shock strut.
Retraction is electric, with aseparate unit for each wheel. The
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Indicative of lavish attention to design, andwide use of ball bearings, are details shownin these field sketches. At top is seen openand closed position of wind-up device onstraps which hold hydraulic lines on landinggear. Note ratchet locking device. Centersketches show how ball bearings used onbrackets are peined in place, then protectedby felt washers and held by simple metalclamps. All elevator hinges, for example,use this type. In many places, as shown inlower sketches, ball joints are provided. Anotched ball bearing race is pressed intoplace, then ball shaped ring is slipped in.When rotated into operating position itcannot fall out; it provides a self-aligningconnection. This type unit is used on rearspar attachments, lower engine mountattachment to front spar, on all jacks, shockabsorber connections and other pointswhere stresses might be raised by fixedfittings.
Engine mount ring is attached to engine mount at four points, loads being distributed tofour corners of fuselage and to bottom of front spar at center line. Also shown are throttlecontrol linkage – leading from left to right side of craft before going forward throughengine mount ring. Detail at lower right depicts throttle itself. Pulling lever back into rearslot kills engine; pushing forward and across quadrant gives double boost for shortperiods. Thumb switch on end of throttle handle controls propellor pitch electrically.
Here is Kommandgerat or “brain box.” Located just ahead of engine mount ring, it isconnected to throttle linkage. When pilot moves throttle lever this hydraulic-electric unitautomatically adjusts fuel flow, fuel mixture, propellor pitch setting, ignition and , atproper altitude, cuts in second stage of supercharger. It is 16-in. High, 16-in. long, and12-in. wide.
motor which turns up 14,000 rpm.,is mounted back of the front sparweb, with a 3.3:1 reduction from thearmature shaft, then a safetycentrifugal clutch, followed by twogearless reductions, one 53:1 theother 60:1, giving a total reductionof 10,494:1 in three steps in a unit14 in. long and, at the front end, 7in. in diameter. The last reductionstage – at the front face of the sparweb – drives a 13/8 in. thick forgedsteel ring to which is yoked atapered aluminum alloy Ibeam of
133/4 in. length. This in turn isjointed to another tapering beaminto the lower end of which isscrewed a ball and socket joint thatattaches to the oleo strut. Theforged ring turns outward to lowerthe wheels and the arms, due totheir toggle action, lock the landinggear down. When turned towardthe airplane center line, the jointbetween the Ibeams or toggle armsbreaks to pull the oleo and wheelup and inward.
It is interesting to not that in
down position the oleo struts havenot yet reached the perpendicular,but there is no down lock on thegear. The two Ibeams form astraight line when the gear is downand this straight thrust, coupled withthe high reduction from the motor,appear to suffice for gear downlocking.
Small metal contacts through fiberinsulation on the faces of the Ibeamjoints automatically shut off themotor when the landing gear is fulldown. On the rotating member ofthe landing gear mechanism there isa small scaled rod which projects upthrough a ball joint in the top of thewings as the gear goes down so thatthe pilot can tell the exact position ofeach wheel.
As gear retracts, the oleo strut justabove the wheel contacts a coupling(set in a boxstructure mounted onthe front face of the front spar)which snaps into place, locks thegear in up position and automaticallyshuts off the retracting gear motor.The lock is held closed by anelectrical latch and releaseselectrically when the power is turnedon to lower the wheels. Unlockingcan be done manually, however: thepilot pulls a knob (on the left side ofthe instrument panel) attached to aflexible cable which, atop the centerof the front spar, is yoked to similarcables leading out to each landinggear uplock box.
The tail wheel is retractedautomatically with the main gear.At the joint of the two Ibeams onthe right main wheel is attached acable that runs over a pulley set justabove the gear spindle, thenceinboard to the right side of thefuselage – in a conduit through thecockpit – back to a pulley on thefront of the diagonal “heart” memberin the fin, then up over a pulley atopit and down to a yoke set at the topof the tail wheel oleo. Thus, and it'snot as Rube Goldbergian as it
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Group assembly showing all oil lines for power plant. All lines going through to fuselageare attached to permanent fittings installed in firewall. A tape at edge of fuselage carriesnumber of each connection; corresponding number is on line itself on encircling tape justbehind union nut.
Oil cooler of FW-190 is set behind armor plate in nose of engine cowling. (Also seeAVIATION for Nov. and Dec., 1942 – “Design Details of the BMW 801 Engine.”)Exploded view at left shows (left to right) armor plate, oil cooler, armor plate, andcowling.
sounds, as the main gear joint starsto move up, tension on the cable istransmitted back to the tail wheelretracting mechanism and the wheelis pulled up. A similar cablearrangement is used to pull thecamera protecting door open whenthe landing gear is retracted. Thecenter wheel fairings are held tightlyopen by a cable system when thelanding gear is down. They areclosed by the wheel when it isretracted.
The tail wheel itself is mountedin a steel fork which fits into thefront end of a heavy steel figureeight casting which places the centerof the yoke 6 in. ahead of the wheelcenter to permit castering. The tailwheel drag yoke attaches to thediagonal empennage member and tothis figureeight casting just ahead ofthe bottom of the oleo strut, whichfits into the aft portion directly overthe wheel center.
At the top of the oleo strut is ayoke containing four rollers; twoload carrying larger ones set on eachside of the center, two smallerlocking ones just aft. These rollersrun in the channel member(previously mentioned in discussionof the empennage) on the aft face ofthe diagonal member, and are part ofthe yoke to which the retractingcable attaches and to which is alsoattached a coil spring going downand aft to the rib holding the lowerrudder hinge. This spring – andgravity – pull the unit down. At the
bottom of the channel the trackleads forward, just enough for thelarger rollers to fit into the resulting“pocket” so that loads from the tailwheel are transmitted up throughthe oleo directly against – andtoward the front – of the diagonalrib, thus locking the wheel in downposition. When tension is put onthe cable from the main gear it
starts the smaller rollers up thechannel and they in turn pull thelarger ones out of the “pocket”, tounlock the gear, and then up thetrack
The tail wheel moves up 20 in.,and rubber pads on the axle justoutside the fork fit snug against thebottom the fork fit snug against thebottom fuselage skin when it is
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Complete fuel tank and line arrangement. Electric pumps are used in each tank andelectric measuring gages are also employed. Filler openings are on right side of fuselageinside quickly detachable cover plates. Forward self-sealing tank holds 61.2 U.S. gal.;aft tank holds 76.8. Tanks are separated by rear spar tie-through member.
This wiring diagram shows: (1) Electric fuelpumps in tanks; (2) battery; (3) radioantennae; (4) radio motor-generator; and(5) master compass which operates electricrepeater head on instrument panel.
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These two detail sketches show armament arrangement on Focke-Wulf 190. At top are two 7.9-mm. machine guns with electricsynchronizing unit just below muzzles; two lines leading down go toinboard 20-mm. cannon (also shown in lower sketch) are locatedjust outside propellor arc.
retracted. A spring loaded “V” camcenters the wheel as soon as the loadis released.
An interesting detail of the tailwheel castering unit is this: the pivotis a hollow steel forging, welded tothe fork and the hollow space isutilized as a grease reservoir forlubricating the swivel surface, thegrease coming out through a 3in.long slot which also serves as thetail wheel lock.
Main landing gear tires are 700 x175 mm. smooth contour and tailwheel tire is 350 x 135 mm., alsosmooth contour.
Stickandrudder controls aregenerally the conventional pushpullrod and cable type, except that theelevator and rudder controls embodydifferential bell cranks which give ahigher control surfacetostick orrudder ratio near neutral position,thus tending to smooth out controlaction at high speeds.
Rudder pedals are stirrup typewith heel plates, with the hydraulicbrake cylinder an integral part sothat exerting toe pressure energizesthe system. Distance of rudderpedals from the pilot's seat can beindividually adjusted by turning aknurled knob set in the pushpull rodon each side of the cockpit aft of thepedals themselves. There are also
four positions for the pedal fulcrumpoint. Rudder pedal units aresuspended from brackets attachedto fuselage bulkhead No. 2. Pushpull rods lead directly aft throughthe fuselage up to the differentialbell crank which is suspended fromthe top longeron at bulkhead 13.From there cables lead aft insidethe empennage skin and attach tothe rudder spar, which is 4 in. wideat the middle hinge.
The 211/4in. long control stickis mounted in a cast base in thefuselage floor center betweenbulkheads 3 and 4. Elevatorcontrol is via a tube leading to the
right side of the cockpit, then viasingle pushpull rod to just aft of thepilot's seat to a bell crank fromwhich two double 1/4in. cables leadback to a differential bell crankmounted in bulkhead 14, whereanother short single pushpull rodleads back to a bell crank directlyunder the stabilizer leading edge anda vertical puspull rod attached tothe elevator horn on the center of theelevator spar.
Aileron control consists of a tuberunning forward from the controlstick base and actuating a pushpullrod and bell crank set on the frontface of the front spar center. From
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Use of FW-190 as fighter-bomber brought installation of this electrically-operated rackbeneath fuselage center for carrying one 500-lb. bomb. Note long light aluminum fairingextending aft from bomb rack itself.
Bottom view of control switch junction box located at left of pilot'sseat. Note how all lines leading out at right have been grouped
into seven quick-disconnect plugs, each one of which is ofdifferent shape so that wrong connections cannot be made.
here pushpull rods extend outboardthrough an idler hinge to changedirection corresponding to the 5deg.dihedral to a point directly in frontof the flap operating motor where abellcrank changes direction aft to thefront face of the rear spar. Hereanother bellcrank changes directionalong the rear spar to the inboardend of the aileron where still anotherbell crank and pushpull rod attachesto the aileron horn. All hinges andconnections are mounted on selfaligning ball bearings. The bellcranks are all mounted on widelyspaced ball bearings so that there islittle lost motion even when thebearings get loose.
The German's extensive use ofball bearings is particularly evidentin the FockeWulf 190 controls, forfinely built ball bearing units areused not only throughout thecomplicated differential bell cranks,but wherever moving parts arejoined and in all the electricreduction gears and motors.
Aileron stick gearing is 3.2 deg. tothe inch; elevator stick gearing is 4.1deg. to the inch; and rudder pedalgearing is 6 deg. to the inch.
Outstanding control on the craft isthe throttle quadrant and itsKommandgerat, or “brain box”.Only one lever, mounted on the leftside of the cockpit is used. From it apushpull rod leads forward anddown to a bell crank attached to arod which runs across to the rightside of the fuselage to a second bellcrank and pushpull rod going upand forward through the firewall toanother pushpull rodbell crank andthe tube unit which takes themovement to the left again a fewinches (to a point inside the enginemount ring) and another bell crank
and pushpull rod which connectswith the “brain box”, a finely builtcomplicated unit measuring 16 x 16x 12 in.
As the pilot moves the throttle,and the movement is transmittedthrough the bell cranks and pushpull rods, the “brain box”automatically makes compensatingadjustments for fuel flow, fuelmixture, propeller pitch setting,ignition, and cuts in second stagesupercharger at proper altitude. If,however, the pilot desires to makea propeller pitch change withoutchanging other settings, he may doso “manually” by pushing arocking lever switch set in thethrottle. Further details of the“brain box” cannot be revealed atthis time.
Another interesting detail of theFockeWulf's design is the enginemount ring, a hollow tubularstructure which also serves as thereservoir for the hydraulic fluidused in the “brain box”. TheBMW801 engine itself wasdiscussed in detail in AVIATIONfor Nov. and Dec., 1942, and thusis not included in this discussion ofthe craft.
All the 190's fuel supply iscarried in two selfsealing tankssuspended by fabric straps in thelower fore fuselage section with thefore tank, between spars, holding61.2 U. S. gal. and the aft tankhaving a capacity of 76.8 U. S. gal.
Both tanks are filled from theright side of the fuselage, the fillerpipe cover plates being quicklydetachable flush units. Each tankcontains a sealed electric pump.Gages are all electric; the fuelwarning light and pump indicatorlights being arranged vertically in
the center of the lower instrumentpanel; the fuel supply gages for eachtank just to their right; and selectorgage to their right. Manuallyoperated fuel selector valve,however, is on the left of the topinstrument panel. Lines from tanksto engine go through the firewall.
Majority of the highly complexelectric system components arelocated to the right of the plane'scenterline. On this side, forexample, are the distributor, twogenerators, battery and mainjunction box with its ground supplyconnecting plug, this latter unitbeing located in the aft fuselagebetween bulkheads 8 and 9.
Wires leading from the removabletop instrument panel – containing sixflight instruments – go out throughthree quick disconnect plugs to theright for power or, as in the case ofthe dash repeater compass, to themaster compass in the aft section.
Two control switch junctionboxes are required, one on each sideof the cockpit. That on the leftcontains the throttle quadrant,propeller pitch control, ignitionswitch, flap and landing gearindicator lights, starter mixturecontrol, stabilizer trim switch andindicator, flap and landing gearswitches, primer pump switch andradio. It is built as a removable unit,and wires going out from its frontend are led through three quickdisconnect plugs, those out the backend to the main junction box throughfive lines in two similar plugs.
The righthand panel containsforward and rear circuit breakers,external battery indicator, fuelbooster pump switches and enginestarter. Four quickdisconnect plugsare installed in the front end; even inthe rear leading to the main junctionbox.
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Quickly detachable flight instrument panel with, left to right, altimeter, bank and turn andairspeed indicators, tachometer, compass and manifold pressure gage. Note use ofquick-disconnect plugs.
The electric system is furthercomplicated by the fact that four ofthe six guns – the two 7.9 mm.machine guns and the two inboard20mm. cannon – must besynchronized to fire through thepropeller. The synchronizing unitsare mounted behind the engine.Electric leads from them go to each
gun.Wherever possible, wires are
grouped when leading from onepart of the airplane to anotherthrough generous use of quickdisconnect plugs. In general, too,the FockeWulf 190 follows theGerman practice of having wiresleading from one part of the plane
to another in the same location, sothat mechanics working on oneaircraft will not have to becomecompletely indoctrinated beforebeing assigned to another make ortype.
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Phantom view illustrates general arrangement of wiring in fuselage, extending from propellorpitch control and distributor at extreme left to stabilizer adjusting motor in vertical fin. Notehow all wires are led to right side of fuselage, those from junction box at pilot's left reachingthat side through conduit in back of pilot's seat before entering main junction box on right sideof aft fuselage section. Outside battery connection is in this box with connecting plug flushwith fuselage skin.
HE FOCKEWULF 190 hasindependently operated mainlanding wheels, each of which
is carried by an arm pivoted at rightangles to, and mounted on, the frontmain spar. It is held in landingposition by a hinged link securingthe wheel by a toggle action whendown.
T Upper half of the hinged link issecured to a rotatable member by afork and pin joint, and the axis ofthis member is approximatelyparallel to the wheel arm pivot.
Rotatable member is the frontend of the electric retracting gear.Each wheel retracting unit is acomplete assembly held to the front
face of the main spar by ten boltswith castellated nuts. Removal ofthe connecting pin and the ten nutsand breaking of two electricalconnection plugs is all that isnecessary to remove this unit fromthe fuselage.
Outstanding features of theretractor are its compactness, lightweight, and unusual method ofgetting a very high gear reduction ina small space. The unit, includingthe motor, measures 131/2 in. inlength and 85/8 in. over themounting flange. There are onlythree reductions needed to give anoverall of 10,500 to 1 fromarmature shaft to the rotating head.
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Design and Operation
Of FW-190 Gear Retracting Unit
By CHESTER S. RICKER, Detroit Editor, "Aviation"
Unusually compact–—measuring only 8-5/8 x 13-1/2 in.—it has over-all reduction of 10,500 to 1. And specialdesign eliminates gear cutting so that production canbe accomplished with grinder, lathe, and drill press.
Cross-sectional assembly drawing of Focke-Wulf 190 landingwheel retracting gear. Note that ball bearings are used onintermediate reduction eccentric and roller bearings for finalreduction. Details of centrifugal clutch between electricmotor and reduction gearing are also shown.
With a 10,000rpm. 27v. motor thismeans a full rotation of the operatinghead in one minute. Since only aquarter revolution is enough to raisethe landing wheel, retraction time isabout 15 to 20 sec.
There is a 3.3to1 reduction inthe motor head so the shaftextending from the motor runs about3.200 rpm. On this are mounted twocast iron shoes, driven by a cross pinand held in place by a continuouscoiled spring band. The latter is stiffenough to hod the shoes in place andto resist centrifugal force so as toallow the motor to attainconsiderable speed before the shoesengage a surrounding drum of steel.This gives an automatic clutcheffect.
The drum is attached to theintermediate reduction mechanism.Giving a final overall reduction of3,180 to 1, the last two mechanismsare compacted into a space of 4 in.axially and of 71/2 in. dia. Bothreductions are also coaxial with theunit, and the casing head rotates inthe final reduction. Apparently nostandard spur gear train of equalratio could be crowded into thissmall space.
The last two reductions, while ofthe same type, are attained withoutgears of the tooth type, instead beingenabled through shallow scallopsground in the edge of hardened steeldisks and engaging hardened steelsleeves that float on pins fixed in thesurrounding housing.
Principle employed is similar tothat sometimes used with toothedgears where an internal gear mesheswith a spur gear having one or moreteeth less than the internal gear, thespur gear being oscillated by aneccentric at its center, but preventedfrom rotation by a pin. The axis ofthe eccentric shaft must be coaxialwith the internal gear. Then fro eachrotation of the eccentric shaft theinternal gear will be advanced onetooth by the spur gear. This designwas used at one time for operatingvariable pitch propellers.
Only difference between theabove gear reduction and that of theFW190 design is that in the latterthe gear teeth are eliminated fromboth members. The aforementionedsemicircular scallops ground in theedge of the disks replace the spurgears, and the internal gear teeth arereplaced by the pins on which the
hardened steel sleeves are mounted.In each reduction two disks are
used so as to give a continuousdrive at all times. The eccentricsare also arranged diametricallyopposite one another so as to keepthe two disks balanced whenrunning.
Another unusual feature of thedesign is the operation giving thetwo reductions. For theintermediate one, the outer memberis secured so that the oscillatingdisks rotate slowly, making one
complete rotation every 53oscillations.
Eight pins engage these oscillatingdisks and thus rotate with them.These pins are mounted in a flangeon the end of the eccentric shaft togive the final reduction. The latterreduction mechanism is mounted onthe flanged forging which supportsthe entire reduction gear and isbolted to the front main spar. Onthis member are eight heavy sleevedpins that pass through the finalreductionoscillating disks and
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Parts of Focke-Wulf 190 retracting gear. At left is electric motor with half of centrifugalclutch and its retaining spring removed. Next is housing containing intermediatereduction mechanism. Clutch drum is clearly shown on this unit. In foreground ismounting plate with its stationary pins, which carry hardened steel sleeves, two of whichhave been removed. At right is final reduction head with operating fork. Retainer platehides oscillating members. This plate, mounted on stationary pins, carries a ball bearingto support outer end of eccentric shaft. (AAF photo)
Reduction mechanism of retracting gear. At left are oscillating disks of intermediatereduction; center, final reduction oscillating disks, with flanged eccentric shaft carryingpins which engage intermediate reduction disks; right, pin and sleeve internal gearmechanism that is attached to wheel lifting arm. (AAF photo)
prevent them from rotating.Therefore they force the internalgear or retracting gear head whichencloses them to rotate one turn forevery 60 oscillations of the disks.
The head is the member which ispinned to the arm that lifts or lowersthe landing gear. To take the liftingload, the outside member is carriedon two roller bearings located oneach side of the internal gear pins.These bearings have 64 rollers, 1/4
x 1/4 in.Outer member is held in place
endwise by a plate secured by eightcap screws engaging the pins usedin attaining the final gear reduction.A cover plate attached to the frontof the rotating outer memberencloses the entire mechanism.
Design of the mechanismeliminates gear cutting by enablingprocessing of the parts with agrinder, lathe, and drillpress.
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DIAGRAMMATIC COCKPIT LAYOUT
ENLARGED
THE FW190A3, newest and“hottest” German fighter plane, is anextremely good craft, but it does notlive up to the claims made for it byNazi officialdom. In fact, bothBritish and American planes can, ashas been proven in combat, morethan hold their own against it.
Nevertheless, many points ofinterest and value to the designer,the production man and themaintenance chief have beenbrought out by inspection and flighttests of British engineers, whosereports have recently been madeavailable. This close study was madepossible when a German pilot wasforced down in England andcaptured before he could destroy theplane.
Created by Kurt Tank, builder ofthe FockeWulf Condor, long rangefourengine bomber and the FW189, short range reconnaissance
plane, the 190 was designed forquantity production and extensivesubcontracting.
It is a lowwing, full cantilevermonoplane with a 34ft. 5in. spanand length of 29 ft. 4 in. Wingconstruction is of conventionaltwospar type, with the wing beingbuilt in one piece. While this haseffected a material saving inweight, it has made maintenancemore difficult. Wing trim tabs aresmall perforated plates on theailerons and are adjustable only onthe ground.
Split flaps are electricallycontrolled by push buttons to threepositions: closed; down 10 deg. fortakeoff, and down 60 deg. forlanding.
Unlike modern Allied craftwhich have elevator and ruddertrim tabs, the FockeWulf stabilizeris adjustable, making it morevulnerable to concentrated firepower.
The fuselage is also built in onepiece and is very well streamlined,narrowing vertically practically allthe way back from the engine. The
entire cockpit cover, including ratherlong fairing, slides back but it cannotbe opened in flight. Emergency exitin flight can only be accomplishedby pushing a button which detonatesa cartridge which breaks thesupporting member, allowing theentire cover to be blown away.
All the fuel is carried in thefuselage in two selfsealing tanks,one of 64 gal. immediately behindthe pilot's seat, another of 51 gal.under the seat.
The electrically operated fullretracting landing gear has a tread of12 ft., apparently made necessary bythe high landing speed —approximately 110 mph. It is also setwell forward to permit heavybraking without nosing over. Aninteresting feature of the landinggear is the tail wheel retraction, acable attached to one of the frontwheels automatically pulling the tailwheel up into its well.
Power PlantPower is supplied by a BMW
801D 14cylinder radial, aircooledengine developing slightly under1,600 hp. at 2,700 rpm. for takeoffand just over 1,750 hp. at 3,000 rpm.at 18,000 ft. Cowling is extremelycloseset, the diameter being but 52in., necessitating installation of alarge fan set just behind thepropeller. The oil radiator is set justinside the nose of the cowling,cooling being effected by a reverseflow through the radiator and outthrough a narrow opening at itsfront. Extensive baffling distributesthe air to all the cylinders with theheated air bing exhausted throughlong louvres cut in the cowlingsides. Unlike the BMW 801A, thereare no facilities for sliding the nosering or cowling at the back of the
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The right side of the inward retractinglanding gear of the Focke-Wulf 190 isshown at left. The locking mechanism at “A”is electrically operated, as is the retractinggear itself, which pivots the rod “B” in andup to pull the gear into the well. Travel ofthe rod tightens the cable “C” which retractsthe tail wheel, thus eliminating the need fora separate power unit for that part of thelanding gear. “D” is the line from the cockpitto the hydrayulic brake. Not that the fairing“E” comes only a little way below the hub ofthe wheel; another piece on the fuselagemoves in behind the retracting wheel tocomplete the underclosure. )For otherdetails of the Focke-Wulf 190 see Aviation,October, 1942, p233.)
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Structural details of Focke-Wulf 190A3 revealed in this cutaway illustration, redrawn from The Aeroplane, include following: Aileron hingebracket and openend shroud are at “A.” with aileron tab—adjustable only on ground—at “B” and aileron control at “C.” “D” is one of two 20mm.cannon firing outside propeller arc. Landing gear radius rod break hinge is at “E,” operating tail wheel retracting cable “F.” Landing gear retractingpower is delivered by electric motor “G,” with position being checked by indidcator “H.” “J” is on of two 20mm. cannon firing through propellerarc. “K” is armor=plated couling enclosing oil cooler. Two 7.9 machine guns are at “N.” Throttle is at “O,” while “P” is 14mm. armor plate toprotect pilot from tear. Adjusting mechanism for pilot's seat is at “Q.” Fuel tanks of 64 and 51 gal. are sown at “R” and the plane's battery is at “S.”Tail wheel retracting cable is at “T” and compass at “U.” Tail wheel lock is at “V” and shock leg guide and block are at “W.” “X” is tail incidencemotor and “Y” shows elevator and rudder tabs. (Also see Aviation, Oct 1942, page 233, and Nov., page 157.)
motor to adjust the flow of air.The electrically operated, three
blade, constant speed VDMpropeller is of rather small diameter— due to landing gear restrictions— but the blades are of long chordalmost all the way to the tips.
Armament and Armor
Armament consists of two 7.92mm. machine guns mounted atop thefuselage firing through the propeller;two 20 mm. Mauser cannonmounted in the wings, also firingthrough the propeller; and two 20mm Oerliken cannon also in thewing but firing outside the propellerarc. Despite the fact that four of thesix guns fire through th propeller,the fire power totals about 3,500rounds per minute — 1,200 for themachine guns; 1,400 rounds for theinboard cannon and, strangelyenough, but 900 for the outercannon. Effectiveness of the firepower is curtailed due to the shortrange of the machine guns and lowmuzzle velocity of the Oerlikens.
Provision is also made forattachment of a 550lb. bombbeneath th fuselage for very shortrange operations.
The plane is well armored. A 5mm. plate protects the oil radiator inthe nose ring cowling and the aftportion for the cowling is fitted with3mm. plate. Cockpit windshield has2¼in. thick bulletproof glass and abulkhead behind the pilot's seat is 8
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FOCKE-WULF
FW-190A3 International News Photo
RIGHT: Flight tests of this Focke-Wulf190A3, captured intact by the British, revealmany unusual design and constructionfeatures but show that the “pride of theLuftwaffe” leaves much to be desired. Notethe wide tread of the landing gear—12 ft.—
made necessary by a landing speed of 110mph. LEFT: This close-up of the Focke-Wulf 190 shows the extremely closecowling around the BMW 80iD 14-cylinderengine, the first radial air-cooled engine tobe mounted in a German fighter. Note the
cooling louvres through which cylinder-cooling air and exhaust are dissipated. Notealso the 20-mm. cannon, set in the leadingedge of the wing; fires through the propellerarc.
Cut-away and diagrammatic views of the BMW 801A engine, forerunner of the Model D installed in theFocke-Wulf 190, the main difference being that on the D the nose ring and motor cooling air regulatorrings are not adjustable. These illustrations, redrawn from “The Aewroplane”, show the large cooling faninstalled just behind the propeller and point up the reverse flow of air.
mm. thick. A 14mm.thick panel isfitted behind the pilot's head in themovable cockpit cover.
Performance Not OutstandingPerformance range of the 190 is
limited, its most effective altitudesbeing above 15,000 ft. and below25,000 ft. Its top speed at 4,500 ft.,for example is but 326 mph.compared with 375 at 18,000 ft. Itcan, however, do 390 mph. at20,000 ft. for one minute by meansof a booster. Reports from Americanbomber crews indicate the FockeWulf does not perform well near itsreported service ceiling of 37,000 ft.British fighters are understood to beable to turn inside the 190, even atits most efficient altitudes.
Specifications and performancedata are as follows:
Wing span.............................. 34 ft. 5 in.Length......................................29 ft. 4 in.Wing area.................................203 sq. ft.Wing loading......................42.2 lb./sq. ft.Power loading..........................5.3 lb./hp.Gross weight..............................8,580 lb.Weight empty.............................6,240 lb.Maximum speed (18,000 ft.).....375 mph.Landing speed...........................110 mph.
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