Saturday, June 21, 2014

British Captured Messerschmitt Bf109G-14 Report

        Profiles :

   At 09:30 hours on 22nd July, a Me.109G-14 was shot down by light A.A. fire near Fontenay-le-Poesnel, making a good belly-landing in a grass field, only 800 yards away from the enemy lines. An obstruction post was hit before the aircraft came to rest, and severe damage was done to the starboard mainplane.
This aircraft is the first of its sub-type to be identified, and presents a number of interesting features. At the present stage of the war the most interesting are, perhaps, those which point to the very short time elapsing between its leaving the factory and its destruction. Technically the aircraft is of interest as it was carrying a special tank containing a fluid known to the Germans as `MW50'. The power boosting qualities of this fluid will be described under the heading of 'Engine' below.
Apart from the fitting of this tank and the installation of FuG 16 ZY, this aircraft is almost identical with the Me.109 G-6/U2

Identification Markings
+ 7 (black outlined yellow)
Call sign: VW+HO
Works No.: 413601
Maker: Mcu. (ed.note: code for Erla- Leipzig)

Light and dark grey upper surfaces, light blue lower surfaces. The lower half of the fuselage sides mottled with patches of grey and green. The spinner is black with a white spiral.

DB605 A-1 Tp
Maker: hsr. (ed.note: code for Henschel- Kassel)
Painted on the crankcase cover is: 605 A/M

         This engine has the normal small supercharger and both engine bearers are of light alloy. C-3 (100 octane) fuel is used but additional power for short periods is obtained from an apparatus known as the `MW 50', in conjunction with a boost pressure of 1.7 ata (equals British boost of +9.5). This is a system of delivering methanol and water to the eye of the supercharger from a light alloy tank (probably of 35 gallon capacity) situated behind the normal fuel tank. The methanol tank is built in during manufacture and cannot be removed for servicing. The pressure side of the supercharger is tapped by a pipe which leads via a relief valve to the top of the light alloy tank, so supplying the pressure for feeding the mixture to the engine. A supply pipeline from the tank to the eye of the supercharger carries the methanol and water mixture. In this pipeline there is a solenoid operated valve and a pressure gauge connection. A switch on the port side of the cockpit beading, marked `MW 50' operates the solenoid valve and is a simple On/Off switch. The pressure gauge, reading from 0 to 3 kgslsq. cm. (0 to 42 lb./sq. in.) is located lower down on the port side of the cockpit. The actual pressure used is between 1.2 and 1.8 kgs./sq. cm. (17 lb/sq. in. -25.6).
It is estimated that the power at sea level, when using `MW 50' with a 1.7 ata boost (equals British boost of +9.5) and 2,800 r.p.m. is 1,770 h.p. The D.B. 605A without the `MW 50' develops 1,450 h.p. at 1.42 ata boost (equals British boost of +5.5) and 2,800 r.p.m. at sea level.

     The boost gauge is marked with a series of red lines on the glass, as follows: d opposite 1.02 ata. = British -0.2 30 opposite 1.3 ata = British +3.8
3 opposite 1.42 ata = British + 5.5 MW 50 opposite 1.7 ata = British +9.5
The figures on the glass refer to the time in minutes for the use of the respective boost pressures, the d8 meaning maximum continuous. The rev. counter is also marked opposite the respective r.p.m.
The sparking plugs are of a type not previously fitted to D.B. 605 engines but they were found recently in the Jumo 213. They are Bosch D.W. 250 E.T. (10/1) and are stamped 5Z (this is the manufacturer's date code and indicates May, 1944).
The magneto is marked 9/4040E, Serial No. 453864. Manufacturer cxo under license from L.Z.U.
The flange bears the following markings: BA 13402 cxo 4Z.

1 x MG151 20 mm. calibre, firing through propeller hub.
2 x MG131 over the engine.

Loading order 20 mm. gun- 1 AP/I, - 1 HE/I/T (S.D.)(M. Geschoss) repeating. This order changed later in the belt to- 1 AP/T - 1 I/T, - 2 HE/I/T (S.D.)(M. Geschoss) repeating.

Loading order for 13 mm. guns- 1 AP/T, - 1 HE/T repeating. Nearly all tracer rounds were night trace, although the aircraft was on a daylight operation.

None of the guns had been fired and it was found that the ammunition tanks had not been completely filled.

            Tank capacity Rounds carried
20 mm 200 per gun 150
13 mm 300 per gun 275
The Revi 16B gunsight was used.

Pilot's bullet-resisting glass screen. The cockpit cover was jettisoned before the crash and could not be recovered. No other armour is fitted to this aircraft.

Internal equipment
     Radio: FuG 16 ZY fitted. 1' aerial mounted on underside of the port wing, 7 ft. 2 in. from wing root and 9 in. back from the leading edge. The aerial itself, which consists of a tapering streamlined light alloy tube 24 1/2 in. long with a semi-flexible stranded wire tip 12 1/2 in. long projects through a 'Plexiglass'
disc set in the wing surface. The aerial matching unit, A.A.G. 16 E-3, Gerat No. 124-1508 E-1. Anfz. Ln. 27185-6 Manufacturer dmr., was mounted immediately above the aerial inside the wing. A single concentric aerial feeder, marked E143, connected the matching unit to the set via a small box, mounted on the base panel, immediately above it. It was not possible to examine this box without removing it, but it is believed to contain a relay. The FuG 16 ZY itself has no aerial ammeter fitted, a blanking plate covering the vacant spot. Four spot frequency selectors were fitted on both receiver and transmitter. The dick stop settings were:
Receiver: - I- blank II- 41.85 39.7 40.9 
Transmitter: - I- blank II- 41.85 39 40.9

    When found both units were on 40.9 mc/s.
No Z.V.G.16, navigational unit, was installed. Bracket for FuG 25, but no units fitted. The four-spot frequency switch in the cockpit was mounted on the lower right of the instrument panel.
The layout of the instruments has not changed, but they were mounted in a wooden panel. Compared with the Me.109 G-6/U2 the following items had been moved:
Battery 24 V. 7.5 amp - from the rear of the fuselage to a point immediately behind the pilot's head. (From the servicing point of view, the battery is badly placed, as it is wedged between the top of the petrol tank and the top of the fuselage, and is extremely difficult to take out.)
The 'taster compass - has been moved from the position immediately behind the petrol tank to its original place at the rear of the fuselage.
Oxygen bottles - These are now in the port wing instead of in the rear of the fuselage.
Tankage - The petrol tank was non-self-=sealing, being made of light alloy. It appeared to be protected only by a box of 7-ply wood. On the other hand, the small priming fuel tank which is fitted in the upper part of the fuselage on the starboard side, some 4 ft. forward of the base of the fin, is self-sealing.

Points of Interest
    The two hand wheels controlling the landing flaps and the tail incidence, as well as the FuG 25 mounting panel, were made of ply-wood.
It is usual for both sides of the landing wheels and oleo leg fairing to have coats of finished paint, but on this aircraft the inner sides were finished in a red primer coat only.
There was wiring for wing guns and also the mountings for ammunition tanks, so that the two wing M.G. 151/20's could rapidly be fitted to this sub-type•
The wiring in this aircraft is almost entirely unscreened.
In previous Me.109's examined, the breech of the gun firing through the propeller hub has projected into the cockpit, but has not been covered. In this machine, however, there is a neat fairing round the breech, and on it are painted instructions concerning engine revs. for delivery flights or test flights after an engine change.      These state: -

(1) On deliver flights or test flights after an engine change, after take-off do not exceed 2,100 r.p.m. and 1.05 ata of boost. If possible duration of flight should not exceed one hour. Watch oil pressure.
(2) For the first five hours, if possible do not exceed 2.300 r.p.m. and 1.15 ata boost.
(3) For the second five hours, if possible do not exceed 2.600 r.p.m. and 1.30 ata boost
(4) After ten hours, the aircraft may be flown if necessary without limitations other than those laid down in current instructions.

In conclusion, tribute must be paid to the excellent co-operation of the salvage party, the Army, and the Royal Navy, which enabled this aircraft to be delivered to R.A.E Farnborough in less than three days after it was shot down in Normandy

Tuesday, June 3, 2014

30x91 Mk108 ammunition

Cutaway models of ten 30x91 shells for the Rheinmetall- Borsig Mk108 aircraft gun. The Mk108 gun was developed during the early 1940's and it was the standard 30 mm cannon in fighters from 1942 untill 1945. It was used in many planes, for instance: the Me109, Me110, Me262, Me163 and the Fw190-A8. It's advantages were: light in weight (58 kg), small size (1057 mm long), easy to build in existing planes. It's disadvantages where: low muzzle velocity (±520 m/s), resulting in a very curved projectile trajectory and a short range. An enemy plane had to be approached quite close to enshure hits. However, if an enemy plane was hit, the results were spectecular; one hit of an M-shell destroyed a fighter instantaneously, 3 to 5 hits were sufficient to destroy any heavy bomber. Another disadvantage was that the cannon, either hull mounted, either mounted in a wing bay, could only take a limited amount of ammo. For the Me109 / Fw190 wing bay mounted gun an average of 55 cartridges/gun, the Me163 could take 60 rounds/gun in the hull mounted guns. With a firing rate of 660 round a minute, this was just 5 seconds of firing before all ammo was spent.
Cartridge cases are made of either brown or green painted steel. The firing cap is electricaly ignited. The main propulsion charge exists of 30 grams Np rifle powder or 29,5 grams nitrocellulose blade powder. Some shells were found to have a small silk bag of fine powder over the firing cap, functioning as an extra igniter charge, igniting the main powder charge with a bigger flame. Data for the projectiles:

Type 1- 3cm brandgranate ohne zerleger (3cm incendiary shell without self destruct element), a pressed steel body with a (typical for the mineshell) round bottom. The shellbody is filled with thermite, pressed in three degrees of tightness, the less pressed amount in top. The shell is fuzed with the Az1587. After hitting the target, the shell's nose is blown off by the initial explosion of the nosefuze, after which it starts spewing fire like a roman candle, about 1200º C hot. weight of shell : 330 ± 8 grams.

Type 2- 3cm M Geschoß 108 ausführung A mit zerleger (3cm Mineshell 108 type A with self destruct mechanism). A Mineshell filled with 85 grams of penthrite and fuzed with the ZZ1589B (Zerlegezunder /self destruct fuze 1589B -mechanical-). The shell could also be filled with 85 grams of HA41 (Hexogen Aluminium). Weight of shell : 330± 8 grams. Note that the shell has a different type of detonator, the VC70. This duplex detonator had a delay curcuit that delayed the shell for about 10 cm of flightpath, enabeling it to enter the target before exploding inside of it.

Type 3 - 3cm M geschoß ohne zerleger (3cm Mineshell without self destruct mechanism). A mineshell filled with 82 grams of Ha41 and a ring of 3 grams penthrite ,surrounding the VC70 detonator. The fuze used is the AZ1587.

Type 4- 3cm M geschoß leuchtspur, mit zeleger (3cm mineshell with tracer and self delay). A Mineshell with a tracer element , used one on five in a belt for fire corrections. The shell is filled with 73 grams HA41 and a core of 3 grams nitropenta. The fuze is an ZZ1589B, in fact a ZZ1589A with a smaller and more streamlinded outer body.

Type 5- A practice mineshell , resembling the 3cm M shell with tracer. The shell is not tarfilled to bring it to the right weight.

Type 6- 3cm panzersprengranate leuchtspur übung ohne zerleger (3cm practice APHE shell with tracer, without self destruct). Weight of shell 500± 7 grams. Fuze dummy : 3cm Bd. zerleger erzatzstuck 1592 (3cm Basefuze replacement screw 1592).

Type 7- 3cm Practice mineshell with unbalance . A tarfilled practice mineshell with a steel rod in the middle that is bend outward on top. This causes the shell to fall into unbalance , shortly after leaving the barrel. Effectively a short range practice shell. Weight 330± 8 grams.

Type 8 - 3cm M geschoß Üb ohne zerleger (3cm practice mineshell without self destruct device). A tar filled 3 cm mineshell, supposedly designed to receive a 20 mm shell fuze.

Type 9- 3cm M geschoß Üb ohne zerleger (3cm practice mine shell without self destruct device). A tar filled practice mineshell, supposedly threaded to receive the ZZ1589B, however only found as an practice shell.

Type 10 - 3cm sprengranate übung ohne zerleger (3cm high practice high explosice shell without self destruct). A machined steel body with a pressed steel windshield.

It must be noted that in most M shells, an aluminium ring can be observed i.w.o the driving band on the inside of the body.This ring is placed to prevent the thin walled shell body from being crushed while the drivingband is pressed into the rifling grooves of the gunbarrel.

The Mk 108 gun was nicknamed "pneumatic hammer" by allied aircrews , referring to the distinct sound of this "tool"

Left , the AZ 1587 (Anchlagzünder 1587 / Impact fuze 1587) a non self destruct impact fuze. Functioning of the fuze. An aluminium firing pin housing, containing the firing pin (see right side above the shell), is held out of line of the detonator. To enable the firing pin to pierce the detonator, it has to move 2mm to the center. A ball on the bottom of the fuze also prevents the firing pin to move to the middle. The ball on its turn cannot move upward, held in place by two centrifugal pins (one at 180º each) which are pushed inward by a brass coiled spring. The ball lies in the right one of two equaly sized holes that are drilled slightly overlapping. The right hole, holding the ball however is drilled 2º outward toward the top. After firing, the pins are thrown outward by the centrifugal force, the ball however is held back until acceleration decreaces. The ball than starts "climbing up the wall" of the 2º drilled hole due to the centrifugal force, towards the top of the fuze, where it falls in the recess of the firing pin housing. The weight of the ball, swung outward by the centrifugal force will now slide the firing pin housing outward (in this picture that would be to the right), placing the firing pin over the detonator and under the hammer pin above it. At impact the hammer pin forces the firing pin into the detonator.

In the middle, the ZZ1589A (Zerlegezünder 1589A / Self destruct Fuze 1589A). Functioning of the fuze: The firing pin is placed in a housing with six holes drilled in a radial pattern in the body. These hold a small ball each. Around the body,a grooved steel ring is placed, The inner groove machined in diameter to receive just under half the diameter of the balls. A strong spring on top of the housing wants to press the firing pin into the detonator, but is prevented from this by a brass coiled roll. After firing , the centrifugal force forces the balls into the groove, the brass foiled roll starts to unwind, forming a hole large enough to let the firing pin and the housing pass. The balls, forced into the grooved steel ring now "lock" the firing pin housing in place. If a target is hit, the firing pin will simply be hammered down into the detonator, exploding the shell. If no target is hit, a moment will come where speed and spin will decreace. At the moment that the downward pushing spring overcomes the locking force generated by the balls in the groove, the balls will be pushed back in the housing and the firing pin will be driven into the detonator. 

Right, the ZZ1589B Internal parts and working as the ZZ1589A , differs only in a smaller fuze body.

Type 11- 3cm M geschoß Üb ohne zerleger (3cm practice mine shell without self destruct device). A practice mineshell with a blind nose piece resembling the ZZ1589B. The filler is made from a mixture of sand and tar. This mixture is locked up by a 1,5mm thick steel plate, locked up by the nose piece.

Type 12- 3cm M geschoß leuchtspur, ohne zeleger (3cm mineshell with tracer, without self destruct). A Mineshell with a tracer element , used one on five in a belt for fire corrections. The shell is filled with 73 grams HA41 and a core of 3 grams nitropenta. The fuze used on this projectile is the AZ1504, which is also used on the 2 cm Spr.Gr.
In functioning it resembles the AZ1587.

Type 13- 3cm SprGr. L'spur o. Zerl. (Sprengranate leuchtspur ohne zeleger / 3cm High explosive shell with tracer, without self destruct). A thick walled high explosive projectile with a drilled tracer element. The shell is filled with Trotyl and has a core of 3 grams Nitropenta, packed in a cartboard tube. The fuze used on this projectile is the AZ1504, which is also used on the 2 cm Spr.Gr. In functioning it resembles the AZ1587.

Bf109G-14AS vs Bf109G-14

Messerschmitt Bf109G-14 DB605AM Engine Performance Curve

Messerschmitt Bf109 Engine Chart

Monday, June 2, 2014

Messerschmitt Bf109 Range With Drop tank

The figure you have given appears to maximum cruise conditions without a droptank, ie. datasheet shows this as 585 km achieved at a cruise speed of 645 km/h (400 mph).

German range tables give the following speeds for the different 109 variants at maximum range conditions, with a single droptank.

Maximum range of Bf 109E-7 with droptank was 1350 km, endurance 3h 50 min.

Maximum range of Bf 109F-4 with droptank was 1660 km, endurance 5h 15 min.

Maximum range of Bf 109G-2/G-6 with droptank was 1700 to 2000 km, endurance 5h 20 min to 6 hours.
Without droptank, it is given as 990 to 1160 km, endurance 3h 5min to 3h 25 min.
(Different documents give different values, probably under different conditions specificed)

From this, for the two droptank version (LR recce variants used this configuration), roughly 2600-2900 km range seems a reasonable figure.

I know of no maximum range table for the 109K, only under maximum cruise conditions (585 km); . Some conlclusions can be drawn from these datas, as the K-4 is listed as with ca 6% greater range than the 109G under maximum cruise conditions, probably down to increased aerodynamic cleanness and/or more efficient powerplant (higher CR motor).

In addition, the 109K had the ability to carry 118 liter (+29,5%) more fuel internally in its rear aux. tank - in this case MW50 was not carried (it used the same tank).

I`d say the 109K-4s maximum range was 1850 - 2100 km, and could be extended to something like 2100-2400 km if the rear tank was used an aux. LR fuel tank (and no MW 50 carried. However with C-3 grade fuel the performance would be similiar as with the lower grade fuel, MW-50).

Messerschmitt Bf109F-4 Range Table