Focke-Wulf Fw 190
Main Landing Gear

Part One - Overview and Operation

by Robert Stephenson and
E. Brown Ryle III

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Introduction

Bob Stephenson and I have been emailing each other for what seems a very long time. The text is usually split between the general stuff of life and hobby related material.

Somewhere among the email Bob mentioned a series of Internet postings on 1/48^th scale Fw190 landing gear asking the question “Which Fw190 stance is correct? Is it the Trimaster, the DML/Dragon, or the Tamiya?” According to Bob, the posted answers were more dependent on the person’s opinion of the model than the study of Fw190 landing gear.

I knew why there were numerous questions about the stance of the Fw190. The Fw190 landing gear is not as easy to understand as it appears.

Bob and I decided to do some research to see what answers we could sort out regarding these questions. We hope the following will be a good primmer on understanding both real and 1/48^th scale Fw190 landing gear. Please note the changover from my part describing the actual aircraft gear to Bob’s part of describing and detailing the nature the model kit gear.

Fw 190 Main Landing Gear

Overview & Operation

The Fw190 undercarriage is a bit different from the average fighter landing gear of its time. The Fw190 gear was: operated by pushbutton control of electric motors in the wings, possessed electric up- and down-locks, and had a control wire running from the starboard strut that retracted the spring-loaded tail wheel. The “look” of the gear is also different: when the gear is extended it has an odd inward cant (Photo 1 below).

Noticeably, all of the tire is positioned forward of the leading edge of the wing (Photo 2 below).

Electric Motor and Folding Drag Links

Photo 3

The front of the electric located motor in each wing. It is mounted in the wing spar inboard of the strut/wing attachment point and provides gear extension and retraction.

A set of folding drag links (Figure # 1 and Photo 4), also called radius rods, connect the rotating drive outer cover (front plate) of the electric motor to the landing gear strut.


Figure 1 - folding drag link	Photo 4 - rear side of landing gear strut showing drag link attachment point

As the electric motor’s face rotates, the links extend or retract the landing gear (Figure 2 below).

Figure 2

This is also how the visual indicator rod protrudes from or recesses into the wing top (Figure 3 below) to inform the pilot that the gear is up or down. The landing gear had indicators in the cockpit, but this was an additional, machanical source of position. Usually, the upper ¾ of the rod was painted red, and lower ¼ painted white. When the gear was extended, and the pilot saw white on the bottom of the rod, the gear was locked down.

Figure 3

Downlock is provided by electric motor gearing (1 to 15,000) and a small pressure spring (Photo 5) that attaches on one end to the rotating face of the electric motor on the outboard side of the drag link and on the other end to the main wing spar.

Photo 5

Without this small spring, the gear will collapse (all modelers detailing their Fw190 wheelwells take note) as soon as the aircraft is moved and lateral shear is applied to the landing gear. Uplock is provided by locking units in the wheelwell that hook onto a small round spur on the aft side of the strut.

Although the gear extends fully for the way it is designed, it does not extend to a position 90° below the bottom of the wing. It stops and locks with the gear having an approximately 13 to14° inward rake as measured from the wing bottom. This inward rake results in the tire being almost directly under the electric motor (Figure 4), not the strut attachment point.

Figure 4

As far as I’ve been able to research the matter, I know of no definitive answer to the reason for the gear’s inward rake. You may consider the following while pondering the design:

a. The drag links of the landing gear are designed to attach almost ½ the way down the strut. This allows for a very stable strut and provides great protection from lateral shear. With the size (length) links they were using, the inward rake may have been necessary.

b. Although there is room inside the wing for a larger electric motor, it may have been decided a smaller and lighter motor, with a smaller rotating face, could be installed by using shorter drag links. Don’t think this would have been a bad decision; even the existing motor, rotating plate, and drag links seem overly strong for this size aircraft.

c. Using two points of attachment to the main spar allows the a/c’s weight to be spread between the strut and electric motor (via the drag links). This affords dispersal of a/c weight along a section of the wing spar as opposed to a single point of the wing spar – which is good. But, the Fw190 main wing spar was rather over-engineered, so this may not be much of a factor.

Gear & Tire Location

The Fw190 landing gear is located rather close to the leading edge of the wing. Looking head-on at the wing, you can easily see the gear cover and especially the tire cover (Figure 5).

Figure 5

The reason the gear is located so close the wing leading edge is that it is in front of the main wing spar, which is the attachment point of the main landing gear. But, the spar must also allow room in front for the diameter of the tire. To accomplish this, the main spar bends forward as it moves toward the wing tip.

Figure 6 (below) shows the Fw190 upper wing. The panel line over the location of the aft section of the wheelwell is the main spar/rear wall of the wheelwell. Note that the panel line angles forward as it proceeds outward toward the wingtip.

Figure 6

The spar bends forward far enough to provide attachment of the strut and clearance of the tire while the landing gear remains perpendicular to the fuselage. This is different from other wing spar/landing gear configurations of the time, but it works well.

The wing’s leading edge extension at the wingroot and the wheelwell area through the fuselage allow the gear’s close position to the wing’s leading edge. When the gear is in the up position, the strut is stowed inside the wing while the tire is stowed inside the wing leading edge extension and the fuselage (Figure 7) - with little room to spare.

Figure 7

[Ever notice that the bottom of the cowling ammo boxes (Figure 4, right side *), located in fuselage wheelwell area, are lower at the center of the fuselage than they are toward the outer edge of the fuselage? That angle is because they were designed to “just fit” over the retracted main landing gear tire, which is positioned inside the fuselage at the same angle.]

As I mentioned, the close location of the gear to the wing’s leading edge, and the Fw190 wing’s taper toward the tip, moves the tire forward of the wing leading edge when the main gear is extended (Photo 2). This forward rake also results from the fact that the strut does not rotate directly downward from its wing attachment point in the spar.

Strut

The wing attachment point at the top of the strut (the bend) is NOT 90° to the gear leg. The angle is approximately 95°. This slight bend can be seen in the strut drawings (Figure 8), the arrangement of the strut attachment point in the wing (Figure 9), and in Photos 6 and 7 of the strut.

Figure 8

Figure 9

Click thumbnails below to view larger images of Photos 6 and 7:

Further:

1.) Look at the upper section of the landing gear cover (Figure 10, right side). Notice that the very top of the landing gear cover, where the strut attaches to the main spar, bents forward. This bend on the upper portion of the cover fits inside the wing when the gear extends. The rest of the landing gear cover is outside the wing when the gear is extended.

Figure 10

2.) Look at any photo of a Fw190 on the ground in which you can see the bottom, aft edge of the landing gear cover (Photo 8). Notice that the bottom of the cover is cut at an angle parallel to the ground (Figure 10, left side) when the gear is extended. This cut is necessary for ground clearance and it varies in size, depending on Fw190 dash number, and the installation of the inner gear door (Figure 11). Also notice (Figure 10, left side again) that this cut is NOT perpendicular to the landing gear strut.

Photo 8

Figure 11

To be Continued

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