Thursday, September 24, 2015

Heinkels against Railways

He 111H-16 `1G+LY' of 14.(Eis.)/KG 27 `Boelcke', Kemenetz, November 1944 While I./KG 27's strategic bombing campaign against the Soviet railway system was short-lived, the anti-railway specialists of 14.(Eis.)/KG 27 spent their entire two-year operational career (from February 1943 to early 1945) flying train-busting missions deep behind enemy lines. Operating alone at night, this Staffel's aircraft wore a variety of appropriate nocturnal finishes, such as that shown here, and eschewed yellow theatre markings altogether. Each was heavily armed (including ventral gun packs), but the jury is still out as to whether the device shown here on the tail of `LY' is a grenade-launcher or (as one source suggests) a glider tug attachment.

KGr. 100 spent the latter half of August 1941 attacking a broader range of targets. Its missions included a night raid on Gomel, a dusk attack on the Dorogobush heavy flak batteries, a night harassment raid on Moscow and the bombing of a Soviet airfield near Vyazma. In addition, crews also went after traffic on the enemy's rear-area roads and railways, seriously disrupting the delivery of supplies to the front. On 23 August one crew put a large Russian railway gun out of action by plastering it with their full load of 32 SD 50 semi-armour piercing bombs.

September 1941, while the ground forces of Army Group Centre prepared to resume the offensive that it was hoped would take them all the way to Moscow, the He 111s of Luftflotte 2 continued their attacks on the enemy's railway network. Returning from one such mission in the Orel region on 28 September, a machine of 1./KGr. 100 was badly damaged by a `taran' attack and forced to make an emergency landing with two of its crew severely wounded.

The Heinkels of KG 53 were heavily involved in Taifun from the outset, at first flying in direct support of the ground forces by attacking Red Army troop and tank concentrations immediately in their path, and then ranging further afield to bomb railway supply lines in the Kaluga and Tula areas to the south of Moscow. But they too were caught completely unawares by the unusually early onset of the harsh Russian winter of 1941/42. On 11 October the temperature suddenly plummeted to minus 22 degrees Celsius overnight; 

`Shatalovka, which had been a sea of muddy puddles yesterday, was today a sheet of ice. The aircraft engines didn't have sufficient anti-freeze. Radiators and coolant pumps froze solid. The crews froze too - their feet, noses, ears and fingers. It was risky to fly for any length of time at high altitudes, as the machines' heating systems could not compete with the intense cold. Oxygen masks froze. Altitude sickness and frostbite were the results.' 

For the first week of Taifun KGr. 100 attacked a wide range of targets, including traffic on the main Smolensk-Moscow highway, Orel airfield and the enemy rail network as far south as Kursk.
The departure of KGr. 100 left KG 53 as the sole He 111 bomber presence in the central sector. From Shatalovka its crews were doing all they could to support the ground forces' drive on Moscow, but they were not finding it easy. The worsening weather - heavy snow showers and low clouds - was forcing them to operate at ever-lower altitudes as they attacked enemy troop positions and the railway supply lines. This inevitably led to an increase in casualties. On 23 October the Geschwader lost five machines, four of them from III./KG 53 alone, including the Kapitäne of both 7. and 9. Staffeln.
After their brief sojourn at Bojary under the temporary command of Luftflotte 2, the Heinkels of I. and II./KG 55 had returned to the southern sector in July and August, respectively. Based initially at Zhitomir, the two Gruppen had first operated in support of Panzergruppe 1's advance on Kiev. They had then transferred down to Kirovograd at the end of August/beginning of September. From here they continued to participate in the developing `cauldron' battle of Kiev by patrolling the roads and railways to the east of the Ukrainian capital and bringing much of the enemy's supply traffic to a virtual standstill. One 3. Staffel crew alone claimed the destruction of seven railway trains in the course of a single mission.

The two Gruppen continued their campaign against the Soviet rail network, as there was more than 2500 kilometres of track within their radius of operations. Such was the efficiency of the Red Army's engineers that no sooner had one stretch of line been destroyed than it was repaired and traffic was soon flowing again. II. and III./KG 55 were therefore ordered to direct their attacks against the rolling stock itself. This paid better dividends. It is estimated that the two Gruppen accounted for no fewer than 222 trains, including 21 ammunition trains and 13 fuel trains, and that 64 locomotives were totally destroyed. The discrepancy between the number of trains and locomotives claimed is partly explained by the fact that, at the first signs of aerial attack, the Soviets would often uncouple the valuable locomotive, which would then make off at full steam, leaving the train to its fate!

In the northern sector there had been no He 111 bomber units at all for the opening six weeks of Barbarossa. The first to arrive in the area were the three Gruppen of KG 4, which had touched down at Koroye Selo, south of Lake Peipus, on 6 August. They flew their first mission in the north two days later - a daylight attack on Soviet troops in the Slepino region - before embarking upon a succession of nightly missions against the Russian rail network stretching from the Estonian border eastwards to Leningrad.

Staffel, 14.(Eis.)/KG 27
Operation Zitadelle was designed to `pinch off ' this bulge by launching simultaneous attacks on its northern and southern edges and then destroy the Soviet forces trapped inside it. The Luftwaffe gathered close on 2000 combat aircraft in preparation for the forthcoming operation. This represented nearly three-quarters of its entire available strength on the Russian front and included all ten Heinkel Kampfgruppen currently operational in the east. Under the newly established Luftflotte 6 to the north of the bulge were II. and III./KG 4 which, together with I. and III./KG 53, were based on fields around Karachev and Bryansk (I./KG 4 and II./KG 53 were both in Germany refitting and re-equipping). South of the bulge, as part of Luftflotte 4, were ranged all three Gruppen of KG 27, plus the eight machines of that Geschwader's specialised train-busting Staffel, 14.(Eis.)/KG 27. First entering service in February 1943, the `Eis.' in this unit's designation was an abbreviation of Eisenbahn, meaning `railway'. KG 27 was concentrated at Dnepropetrovsk and Zaporozhe.

Specialised anti-railway Staffeln, 14.(Eis.)/KG 27 and 14.(Eis.)/KG 55, the latter having been created in June 1943 by the redesignation of 9./KG 53. Rarely more than a dozen aircraft strong - and frequently reduced to as few as three or four serviceable machines each - they were to continue their train-busting activities throughout 1944 and into 1945, the former under Luftflotte 4 in the south and the latter under Luftflotte 1 (and subsequently Luftflotte 6) to the north.

Focke-Wulf Fw 190 A-5/U8

A rarely-photographed Focke-Wulf Fw 190 A-5/U8.

The A-5/U8 was another Jabo-Rei outfitted with SC-250 centreline-mounted bombs, under-wing 300-litre drop tanks and only two MG 151s; it later became the Fw 190 G-2.

The Fw 190 A-5 was manufactured from November 1942 until August 1943. The U8 conversion was a long-range fighter-bomber (Jabo-Rei). Beneath each wing is a 300-l fuel tank on a so-called “Ju 87 Rack”. The tanks were not jettisonable and seriously reduced the aircraft’s maximum speed, consequently this type of rack was not put into production. Beneath the fuselage is an ETC 501, which could accommodate a bomb or auxiliary fuel tank. When this rack was fitted, it was standard practice to lengthen the mainwheel fairings to at least partly replace the missing wheel well doors. 

The MG FF cannon in the outer wings and the fuselage-mounted MG 17 machine-guns were removed, and armament was limited to two MG 151 cannon in the wing roots. Note the unusual red underside of the engine cowling. The photograph was taken in the summer of 1943, however the unit to which the aircraft belonged is not known. It has a factory-applied camouflage scheme of RLM 74/75/76 supplemented by patches of 74/75 on the fuselage sides. Photo by Hauptmann Rolf Schödter III./JG 26’s technical officer

Tuesday, September 22, 2015

Flight characteristics

Messerschmitt Bf 109 undergoing wind tunnel testing in 1940

Flight characteristics - Climb and Ceiling

1."climb rate"
This defines the maximal vertical speed of an aircraft when climbing, while *retaining airspeed*. So no drop in airspeed is permitted for max. climb rate. Climb rate is usually defined in feet/minute

2. "initial climb"
Same as for climb rate, but only for the situation directly after take-off. This figure is important when trees or other high objects are in the direct vicinity of the runway. Aircraft should have a vertical clearance of 15m (45 feet) to any nearby object. So if an aircraft has a poor initial climb, the area adjacent to the runway should be clear of tall objects.

3. "Ceiling"

Ceiling = maximum height (usually measured in feet).

There are two ceilings actually. The operational ceiling (which is the one you probably refer to) and the aerodynamic ceiling.

The first defines how high an aircraft can fly 'normally', thus no drop in airspeed, and reasonable figures like stall speed.

This is where we get to the aerodynamic ceiling. At a certain altitude the aircraft is limited in the 'allowable' speeds. The margin between stall speed and maximum attainable airspeed narrows down to 0 at the so-called 'death man's corner'. A Lockheed U-2 spyplane has an airspeed margin of 30 kts at it's operational height, which is a very narrow margin!

4. "Service Ceiling"
The ceiling at which an aircraft can be flown operationally, which is economically sound or prescribed by the aircraft's mission. As stated, this service ceiling is ridiculously high for the U-2, with little margin for mistakes.

In American usage, "service ceiling" is the altitude at which an aircraft's rate of climb falls to 100 feet per minute. I just skimmed an English book in which they claimed that "service ceiling" was the altitude at which the rate of climb fell to 500 feet per minute. Considering that most WW2 aircraft, other than fighters, have INITIAL rates of climb around 500-700 feet per minute, this would seem a rather harsh standard. Maximum ceiling is worthless for comparisons.

Many German rates of climb are given in meters per second, which I believe is what is displayed on rate of climb indicator gauges (at least modern ones). Comparing an aircraft rated at "22 m/sec" against an aircraft rated at "5.6 minutes to climb to 20,000 feet" is a bit unfair because the second aircraft might have a very impressive rate of climb for the first 1,000 feet.

Flight characteristics - Speed calculation and Actual

Indeed speed comparisons are very tricky. Many still thinks that Bf110 was slower than a Hurricane, in fact it was faster at some altitudes and rarely British Fighters made their claim top speed. 

For example, during test in 1940 Hurricane Mk I's averaged 315mph as opposed to 340mph advertised and Spitfire about less than 360 as opposed to 369mph advertised. 

Many German Pilots swore that Me109E was faster than Spit Mk I (on paper about 10mph or so slower) 

The difference lie in acceleration. Bf110 was faster than a Hurricane but took a lot of time to get there where as British fighters has good acceleration. And when you are turning and looping you can't make the level top speed. The best way to get faster is to dive and it is another virtue not much relating to level speed. 

Perhaps max. level speed does not matter that much what matters is acceleration, drag to lift ratio, diving and climbing. Even still valid today. New generation aircraft are all have slower top speed. (F22 Mach1.7, JSF about 1.5, F18E/F Mach 1.7 however good old Mig23 do well over Mach 2... for a few minutes so it has no operational value)