27 September 2007

Messerschmitt Bf 109 K-4 Instrument Panel

Hi there! Today, I post my first Luftwaffe instrument related post: the instrument panel of the Bf 109 K-4 (Bf was used instead of Me in the original K-4 manual, therefore I use Bf). The information is from an old website of mine, but perhaps most of you have not seen it before. The topic is somewhat different from the photo postings and I am not sure if I should open a separate blog for instruments and aircraft parts related topics. I added a voting poll so that you can decide what you prefer in the future. Enjoy! Your LW collector.

The following Part-One describes navigation and engine control instruments and equipment of the Bf 109 K-4 main instrument panel. Part-Two deals with the round counter box and armament equipment on the upper instrument panel.

GENERAL: The instrument panel of the Messerschmitt Bf 109 K-4 consists out of the Main Instrument Panel (made out of plywood with a thickness of 15 mm, roughly 1 mm per layer), the Blind Flying Panel (made out of plywood with a thickness of 8 mm, 7 layers), the so-called Geraetebretttraeger (mounting bracket for main panel), and (if the Retrofit R1 was used) the auxiliary panel for the ZSK244 bomb switch box which was attached to the lower center of the main panel.

The Blind Flying Panel Fl 22000-1, which carried delicate instruments like the air speed indicator, altimeter, etc. was attached to the Main Panel with four rubber shock mounts. The Main Instrument Panel was attached with hexagonal screws (M6x58, LgN14180.1) to the Geraetebretttraeger which itself was fixed to the windshield assembly.

The Geraetebrett carried not only the main instrument panel but also control instruments for the armament, a pressure gauge for the MW50 equipment (or the clock, respectively), and the Revi 16B gunsight mounting. Critical values on instruments were distinguished with red markings applied directly onto the front glass of the instrument or by means of adjustable markers inside the instruments.

The following sections describe each instrument of the Me 109 K-4 instrument panel. The Anforderungszeichen Fl (instrument code for flight equipment) and the designations for the electrical system are highlighted.

(1) AIR SPEED INDICATOR Fl 22234: The air speed indicator (Fahrtmesser; 100 to 900 km/h) was mounted on the upper left side of the Blind Flying Panel. It was connected to the static as well as dynamic air pressure flexible tube (see figure below). The pitot tube was installed in the left wing tip (in flight direction). The indicated air speed usually did not exactly match the true air speed since the dynamic pressure was not only dependent on air speed but also on air density. The air speed indicator was designed for low altitudes. Hence the error increased with increasing altitude. Therefore the maximum allowed indicated air speed decreased with increasing altitude. The speed limits for different altitudes were indicated with red markings on the instrument front glass (at 400, 500, 600, 700 and 800 km/h for the maximum allowed air speed in 11, 9, 7, 5, and 3 kilometers altitude).

(3) RATE OF CLIMB INDICATOR 22386: The rate of climb indicator (Variometer) was mounted on the upper right side of the Blind Flying Panel. It had a measurement range of +/- 30 m/s and was connected to the static pressure flexible tube and to the compensation container (see figure below). There existed three major types of dials with a slightly different font type. Early ones had only 10-20-30 m/s on the dial compared to later ones with 5-10-20-30 m/s. Some of the indicators had a bulge on the lower side which usually was used for adjusting the pointer in e.g. altimeters. However, all of the rate of climb indicators with this bulge I have seen so far did not have the possibility for adjusting the pointer.

(2) COMBINED ARTIFICAL HORIZON / TURN & BANK INDICATOR Fl 22410, 22411, 22415: The combined artificial horizon and turn & band indicator (Wendehorizont) 1L104 was used for indicating the position of the aircraft with regard to the horizon. It was mounted in the top center of the Blind Flying Panel. The Wendehorizont was driven by a converter, which was attached to the left fuselage side behind the instrument panel. The original spare parts list mentions a Fl 22410. However, all of the three above mentioned types were used (late war fighters usually had a Fl 22411 or Fl 22415).
(4) ALTIMETER Fl 22322: The altimeter (Fein- und Grobhoehenmesser) was mounted on lower left side of the Blind Flying Panel below the air speed indicator. It was connected with the static pressure flexible tube (see figure above). In spite the fact that most late war fighters were equipped with the Fl 22322 (measurement range 13 km) and photos of an original panel show the Fl 22322, also the use of the Fl 22320 (measurement range 10 km) is documented in other fighters (Fw 190 D-9, Me 262).

(5) REMOTE INDICATING COMPASS Fl 23334: The remote indicating compass (Fuehrertochterkompass FT / f2; Geraete-Nr. 127-113 A-2) 1L101 was mounted on the lower center of the Blind Flying Panel. It received the input signals from the main compass (Mutterkompass) mounted in the rear fuselage. There existed different types of this compass. Some had a grey casing, some black. Early types had riveted data plates whereas later ones just had a white imprint. Some of the panels received the latest version of the compass (FT / f8; 127-659 A) with a much shorter casing made out of some kind of plastic. It had a rectangular front and the airplane symbol had just a white outline and was not filled white (some of the FT / f2 had this feature as well).

PART II will follow soon!

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