cherry blossom
Senior Airman
- 504
- Apr 23, 2007
On another forum, someone raised the question whether the Luftwaffe could have effectively attacked British Atlantic convoys if they had developed air to air refuelling before July 1940 (without the British finding out about their experiments). Air to air refuelling had certainly been developed before 1939 although the fuel transfer rates may have been slow. The question seems to depend on the range of a Ju-88A5 which was the version of the Ju-88 in production in July 1940.
I suspect that British convoys had to pass through a square about 200 miles across North and West of Rockall and moved slowly enough that they would be within that square in daylight on at least one day. The square is approximately equidistant from Norway and France, so if the convoys sail further North, they are closer to Norway, and further South, closer to France. This square is outside the effective range of any British fighter of 1940-41 with a chance of catching a Ju-88. German aircraft have to fly roughly 1000-1200 miles from either France and Norway to this square, avoiding flying close to British airfields (excluding Vágar Airport in the Faroe Islands which was built in 1942–43). The Fw200C was capable of flying to the area from France, attacking a ship and flying on to Norway. However, there were few Fw200s in 1940 and they were fragile.
Thus the question is do there exist points South and East of the box where a Ju-88A5 carrying at least 500 kg of bombs externally and a refuelling system can be refuelled so that the bomber can drop its bombs and return to either France or Norway if refuelling fails or if refuelled successfully can search for about an hour in the box, attack a convoy and then return to either France or Norway? Ideally loses would be lower if the Ju-88A5 could also return if one engine failed. Unfortunately, the range of a warplane is a rather elastic concept. It is fairly clear that air to air refuelling would have allowed a reconnaissance variant of the Ju-88A5 to find British convoys. The Ju-88D was developed slightly later by adding fuel tanks and removing equipment such as divebrakes from a Ju-88A4. Its empty weight is given as 8,850 kg compared to 9,860 kg for a Ju-88A4. Its range is given by Stewart Wilson's "Aircraft of WWII" as 2,980 miles or 4,795 km. This may be a gross exaggeration calculated by excluding climb and any allowances but that hardly matters as it is only 400 miles short of the Fw200's range (and we know that that could manage without refuelling). For the bomber, the issue is less clear. The Ju-88A4 has a maximum take off weight of 14,000 kg. We will ignore the idea that it might be safe to refuel one to a higher weight in the air. Thus for an A4, we could carry 500 kg of bombs, perhaps 1040 kg of crew, oil, coolant and ammunition (is that reasonable?) and thus about 2600 kg of fuel. This is more than the 2900 litres (approximately 2088 kg) quoted by a poster on the original forum but extra tanks could be fitted in the Ju-88 bomb bay. A brief glance at the internet finds ranges of 1,696miles (2,730km) or 1,429 miles (2,430 km) down to 1100 miles for the Ju-88A4. The Ju-88A5 might go further at 14000 kg because the A4 carried significantly more armour but might have less efficient engines.
So my question for the experts is can we imagine 50 Ju 88s taking off at dawn from France with 16 carrying 500 kg of bombs and the others equipped as tankers (2 spare). After perhaps 2 hours, first the tankers pair up and one tanker is refilled to max, then the less full tankers each top up a bomber and head for home. Somewhere near Rockall, the remaining tankers top up the bombers and leave. Then can a Ju-88A5 make an attack and get home without running out of fuel?
I suspect that British convoys had to pass through a square about 200 miles across North and West of Rockall and moved slowly enough that they would be within that square in daylight on at least one day. The square is approximately equidistant from Norway and France, so if the convoys sail further North, they are closer to Norway, and further South, closer to France. This square is outside the effective range of any British fighter of 1940-41 with a chance of catching a Ju-88. German aircraft have to fly roughly 1000-1200 miles from either France and Norway to this square, avoiding flying close to British airfields (excluding Vágar Airport in the Faroe Islands which was built in 1942–43). The Fw200C was capable of flying to the area from France, attacking a ship and flying on to Norway. However, there were few Fw200s in 1940 and they were fragile.
Thus the question is do there exist points South and East of the box where a Ju-88A5 carrying at least 500 kg of bombs externally and a refuelling system can be refuelled so that the bomber can drop its bombs and return to either France or Norway if refuelling fails or if refuelled successfully can search for about an hour in the box, attack a convoy and then return to either France or Norway? Ideally loses would be lower if the Ju-88A5 could also return if one engine failed. Unfortunately, the range of a warplane is a rather elastic concept. It is fairly clear that air to air refuelling would have allowed a reconnaissance variant of the Ju-88A5 to find British convoys. The Ju-88D was developed slightly later by adding fuel tanks and removing equipment such as divebrakes from a Ju-88A4. Its empty weight is given as 8,850 kg compared to 9,860 kg for a Ju-88A4. Its range is given by Stewart Wilson's "Aircraft of WWII" as 2,980 miles or 4,795 km. This may be a gross exaggeration calculated by excluding climb and any allowances but that hardly matters as it is only 400 miles short of the Fw200's range (and we know that that could manage without refuelling). For the bomber, the issue is less clear. The Ju-88A4 has a maximum take off weight of 14,000 kg. We will ignore the idea that it might be safe to refuel one to a higher weight in the air. Thus for an A4, we could carry 500 kg of bombs, perhaps 1040 kg of crew, oil, coolant and ammunition (is that reasonable?) and thus about 2600 kg of fuel. This is more than the 2900 litres (approximately 2088 kg) quoted by a poster on the original forum but extra tanks could be fitted in the Ju-88 bomb bay. A brief glance at the internet finds ranges of 1,696miles (2,730km) or 1,429 miles (2,430 km) down to 1100 miles for the Ju-88A4. The Ju-88A5 might go further at 14000 kg because the A4 carried significantly more armour but might have less efficient engines.
So my question for the experts is can we imagine 50 Ju 88s taking off at dawn from France with 16 carrying 500 kg of bombs and the others equipped as tankers (2 spare). After perhaps 2 hours, first the tankers pair up and one tanker is refilled to max, then the less full tankers each top up a bomber and head for home. Somewhere near Rockall, the remaining tankers top up the bombers and leave. Then can a Ju-88A5 make an attack and get home without running out of fuel?
