Defeating Bomber Command

[Koopernic]

Wikipedia seems very optimistic in this case. According to what I have the Ju 88 with external bombs was about 255 mph at about 17,000 feet.

A Blenheim IV and DB7/Boston are faster - the DB7 by a huge margin.

I don't have real tests on the types but the LeO 451 and Tupolev SB certainly appear faster as well.

With 4 x 500 kg external bombs the Ju88's speed is actually more in the region of a Fairey Battle (without external), Hampden (without external) and Wellington II.

Which Ju 88?
Ju 88A1 with 1200lb Jumo 211B
Ju 88A5 with enlarged wings and 1200hp Jumo 211B
Ju 88A4 with enlarged wings and 1350hp Jumo 211F 1941
Ju 88A4 with enlarged wings and 1420hp intercooled Jumo 211J early 1942
with or without dive brakes fitted? It's a complicated area.

The time period we so far have been focused on is about is 41/42.

The speed given is actually 269mph, probably with 4 x 500kg bombs, possibly they were SD (armour piercing) rather than SC (light case)

Early 1943 period Ju 188 started to appear with the BMW 801 engine and a new fuselage with a more flexible bomb arrangment. The Ju 88S and G received the new engines and enlarged tail and wings but retained the slimmer fuselage. The Ju 88R fighter was basically a Ju 88C but with the more powerful BMW 801 engine, it was in limited supply due to the BMW 801's value to the Fw 190 program. 1942 also sees the Dornier Do 217 which had a rather large and sensible bomb bay. A direct application of the BMW 801 to the Ju 88A4 bomber does not seem to have been done though it was possible given the Ju 88C to Ju 88R transformation for the fighters.

Of course the Ju 88's trick was dive and slide bombing and carrying a pair of torpedos, most other light bombers could do non of these as well and certainly not with an internal bomb bay. The A-20 Boston itself went through engine upgrades starting out with R-1830.

The point I suppose I am making is that were the Luftwaffe content with attacking with only 28 x 50kg/110lbs of bombs (3100lbs) in its internal bomb bay then the Ju 88C might have been rather hard to intercept given the performance of the Beaufighter night fighter at that time.

One factor which turned out to be rather important was the amount of armour carried and the Ju 88 was fairly well protected, Even the gunners glass was bullet resistant, otherwise the Blenheim and battle would have continued service throughout the war.

Progression of the type:
Ju 188E 310mph
Ju 188A 322mph
Ju 88G1 344mph with gun pack
Ju 88S1 388mph with GM-1, Ju 88S2 with turbocharged BMW 801TQ, probably about same speed but no need for GM-1.
Ju 88G6 about 365 with Jumo 213A engine
Ju 88G7 about 400mph with Jumo 213E (two stage intercooled)
Ju 388L about 388mph with BMW801TQ service ceiling 44000ft. Large bomb bay.
Ju 388L3 with Jumo 222E/F about 444 mph. Large bomb bay.

 

[Koopernic]

Some had 2 speed engines.

Check Table II: FTH MS 4,600ft, FS 12,100ft for climbing
and Table IV: FTH MS 8,500ft, FS 15,600ft all out level speed.

http://spitfireperformance.com/beaufighter/x7542speed.gif

Serves me right for using Wikipedia. What date did these enter service, it seems 1942? According to Wikipedia the Hercules was effectively what in US parlance was an R-2400 while the BMW 801 would have been an R-2600. Somewhat surprisingly the Hercules has an larger overall diameter despite its smaller swept volume and not requiring rockers and rocker covers due to the sleave valve. This is probably an indication of how much BMW squeezed in to that engine and why they used forced cooling and why the Hercules was unattractive as a single seat fighter engine despite its power. Nevertheless in its niche of powering the beufighter and giving that aircraft good low to medium altitude performance while carrying a great deal of load justified this engine.

 

[wuzak]

Wiki's Hercules page is a bit short on info, particularly variants.

 

[wuzak]

Hercules I, 1936, single speed, single stage
Hercules II, 1938, single speed, single stage
- Beaufighter I
Hercules III, 1939, two speed, single stage
- Beaufighter I
Hercules IV, 1939, single speed, single stage
Hercules V, 1939, single speed, single stage - civil version of IV, not developed
Hercules VI, 1941, two speed, single stage
- Beaufighter I, VIC, VIF, TFX
Hercules VII - similar to VI, but cancelled
Hercules VIII, single speed, single stage - high altitude version of II
Hercules X, 1941, two speed, single stage - development of III
- Beaufighter I
Hercules XI, 1941, two speed, single stage - development of III
- Beaufighter I
Hercules XII, 1941, two speed, single stage - development of VI with separate induction pipes
- Beaufighter I
Hercules XIV, 1942, single speed, single stage - civil development of IV
Hercules XVMT, 1942, single speed, single stage - high altitude version of II with turbo
Hercules XVI, 1942, two speed single stage - similar to VI
- Beaufighter VIC, VIF, TFX

etc

From Lumsden, British Piston Aero Engiones and their Aircraft

 

[Juha]

... I would suggest that the Ju 88C4/C5/C6 would have had the same speed as the Ju 88A4; 317mph. I would say 3000lbs of bombs and single bomb rack fitted to carry a single 900L drop tank would make the Ju 88A4/C4/C6 difficult to catch by the Beaufighter depending on altitude. The Hercules engine was more powerful and the beaufighter smaller but the Jumo 211 had less drag and a better/equal altitude performance....

A bit optimistic, max speed for Ju-88 C-6 with SN-2 antennas at 11,5 to was 460km/h, add the speed loss by antennas (22km/h) one got 482km/h (300mph) and I doubt that with 1.400kg bomb load Ju 88 C would have been heavier and slower.

 

[Shortround6]

I am having a bit of trouble with the range figures for the JU-88 also.

" In this configuration range was just over 1100 miles at max cruise."

Figures from an old book by William Green ( who did make a few mistakes, so correction welcome) are for.

A-1, range with 369imp gallons (all that fit in the wing) 620 miles at 217mph at 18500ft. With 268imp gal tank in forward bomb bay, 1055 miles.
A-4, normal range with 637 imp gal (forward bomb bay tank) 1112 miles.
C-6c, with 369imp gal, 645 miles, with one 105 imp gal and one 230 imp gal fuselage (bomb bay) tanks 1230 miles.

Please note that these are NOT at maximum cruising speeds. Economical cruise for the A-4 is given as 230mph at 17,390ft and max cruise as 248mph at 16,405ft. Max speed at 30,865lbs was 269mph at 14,765ft and max speed at 27,557lbs was 292mph at 17,390ft.
The C6c was faster but then the performance figures are for a plane weighing 26,125lbs. Please note that full internal fuel (tanks in the bomb bay) for the C6c weighed about 5070lbs with doesn't leave much for a bomb load even on under wing racks once you put crew, ammo and oil on board.

It would seem that the JU-88 would have trouble reaching targets with a significant bomb load unless it is out side the plane with impact on speed and range.

Figures for the JU-88S are given a bit different, but are as follows.
Max continuous cruising speed 328mph at 18,000ft. economical cruising speed 289mph altitude not given.
Endurance with 369 imp gallons of fuel 1 hour 40 minutes at max continuous and 2hr 45 min at economical.
Endurance with 637 imp gallons of fuel 2 hours 50 minutes at max continuous and 4hr 40 min at economical.
Endurance with 787 imp gallons of fuel 3 hours 25 minutes at max continuous and 5hr 45 min at economical.

Plane could carry 14 143lb SD 65 bombs internally in the forward bay with the rear bay housing a 149.6imp gal fuel tank, of course if you want to use the GM-1 power boost system IT went in the rear bay and weighed 400lbs empty and another 900lbs when full. Granted the plane was pretty zippy when clean (no bombs underneath) and using the GM-1 system but that makes for either a very short range range bomber or one with very little payload.

I have no idea what the speed and range are if you stick a fuel tank in the forward bay, GM-1 in the aft bay and hang a pair of 2205lb bombs under the wing roots.

However, and rather obviously, any use of the GM-1 system blows the range/endurance figures totally out of the water.

 

[Koopernic]

A bit optimistic, max speed for Ju-88 C-6 with SN-2 antennas at 11,5 to was 460km/h, add the speed loss by antennas (22km/h) one got 482km/h (300mph) and I doubt that with 1.400kg bomb load Ju 88 C would have been heavier and slower.

According to other posters in this thread the Ju 88C series used as night intruders during that period did not carry forward looking radar, presumably it was too secret, that's why I suggested it would have the same performance a the Ju 88A4 minus dive brakes and bomb shackles. The two bomb bays that were fitted with fuel tanks could be retasked as pure bomb bays if desired. The speed of 317 mph seems quit reasonable with a full clean MTOW internal bomb load, it really isn't that much of a load for 2840hp of power. I don't think we even need to make deductions for fuel burned off.

The Luftwaffe did maintain a desire to continue night intruder operations i.e to attack RAF night bombers on their air fields and on their way home to base. It required an aircraft of exceptional range, speed and of course radar fit out. All of these were starting to come together in late 1944 and 1945.

There was a new wave of radars for instance which could tolerate being compromised. Gebhard Adders in his history of the German night fighter force deals somewhat with these specifications. In more colloquial terms the "Luftwaffe secret project" series also does. Apart from Jets such as the Arado 234P there was the Dornier 335 with microwave radar built into the leading edges, they actually built the wing with the dielectric covers for one. The 400mph Ju 88G7 might have done a reasonable job, advanced variants of the He 219 and the Ta 154, had it not been cancelled.

The SN-2 radar is a late war radar, I'm surprised if many C6 were equipped with it as the more capable Ju 88R and Ju 88G1 had been around by then. Shortages of BMW 801 engines aside.

 

[Koopernic]

Fuel burns, fuel capacities for various speeds and bomb configurations are given for the Ju 88A1 here. In German at this point. I'll try a translation next weekend or so.
Beim-Zeugmeister: Page 6 - Ju 88 A-1, set-up state B, loading case 4 with 2 x 500kg bombs
Beim-Zeugmeister: Page 6 - Ju 88 A-1, set-up state B, loading case 5 with 4 x 250kg bombs
In the above configuration, at max cruise speed, the fuel burn rate is 510 Litres per hour, tank capacity is 3580 Litres. Cruise Speed at best altitude is 385 with bombs and 430 without.

Data is given for speed in a climb on those tables. That gives 7 hours endurance x an average of 407kmh = 2849km (about 1770 miles) . Deduct 2 hours or 31% for reserves, combat and climb out comes to about 1250 miles with 1000kg/2200lbs external bombs.
Drop the power of the engine and fuel consumption drops about 22% but speed about 11% so about a 10% increase in range (1375 miles). External tanks could be carried with the external bombs.

The A5/A4 with different wings and engines would be different. The Ju 88A4 load out is here http://www.ww2aircraft.net/forum/we...oadouts-individual-bomb-sizes-makes-9040.html.

Removing both internal bomb bay tanks sacrifices 1220 + 680 Litres (total 1900L) which can effectively be restored by carrying 2 x 900L drop tanks which of course would ideally be jettisoned.

The above calculations are certainly with dive brakes fitted though with the appearance of the Stuvi 5B and BZA computing shallow dive bombing sight the dive brakes could be removed.

Carrying 4 x 250kg bombs seems to have only a modest impact on cruise speed 430kmh->385kmh (about 10%). One might expect a similar deduction in max speed: about 310mph (without dive brakes) -> 279mph.

By 1942 the Luftwaffe had the Do 217E which could carry 2000kg/4400lbs internally with uncompromised fuel load at a speed of 322mph, a little more if armour piercing bombs were used and external carriage was allowed. It could still be fitted out with 2 x 900L tanks.

The faster Ju 88S was used for path finding and target marking. For certain roles such as dive bombing and torpedo bombing external carriage is de rigour and that is what the Ju 88 excelled at. It's worth pointing out that not a single ship was sunk by level bombers during WW2, skip bombing aside.

The Ju 88 was used as a tank destroyer, simply using its dive bombing capability and the Stuvi 5B to do the job. A pair of 500kg bombs sufficed but the more skilled Finnish pilots liked to use a pair of SC-1000. The dive would commence at 8000ft, pull-up complete at 5000ft, speed reached 400mph, accuracy good enough to destroy a tank.

 

[Shortround6]

See above, a JU-88 running clean has a real problem with fuel, You either have enough to reach the targets and go fast but no bombs or you carry bombs and either can't reach the target AND go fast. Not without turning it into a one way mission.

Drop tanks may help but getting bounced on the way to the target may mean aborting the mission. The JU-88S having a range of 544 miles at MAX CONTINUOUS cruise wing wing tanks only. Use of full power or GM-1 will shorten that considerably. Granted MAX cruise is not needed for the entire return flight.

 

[wuzak]

And the Ju 88S would likely run into later model Mossie NF - maybe even XXX.

 

[Glider]

So I think its fair to sum up by saying that the Beaufighter is more than capable of dealing with the majority of the Ju88 combinations at night. When the later enhanced versions are on line the Mosquito has a comfortable advantage. So whilst it was probably worth trying every now and again a constant intruder campaign would be unsuccessful.

 

[Juha]

Hello Koopernicyes, I'm aware that the intruder Ju 88 Cs didn't have radar, thats why I corrected the max speed of the radar equipped C-6 with the info got from the same flight test report on the effects of the SN-2 antennas (460km/h+22km/h=482km/h) to get the true speed of a radarless Ju 88C-6 at 11.5 tonnes weight.
Now according to Mackay's Junkers Ju 88 (the nearest source I have others but didn't bother to dig them out) the AUW of the Ju 88A-4 was 13,995kg, so I think that a Ju 88 C with 1,400kg bomb load would be heavier and slower than that Ju 88 C-6. And if we believe Mackay the max bomb load of a C-6 was 500kg, he doesn't give the possible bombloads of the other C versions.

PS I looked Mackay's book a little more carefully, C-2, 316gal fuel tank in the forward bomb bay, so IMHO max 500kg of bombs in the rear one, C-4 bomb equipment delated.

 

[Glider]

The faster Ju 88S was used for path finding and target marking. For certain roles such as dive bombing and torpedo bombing external carriage is de rigour and that is what the Ju 88 excelled at. It's worth pointing out that not a single ship was sunk by level bombers during WW2, skip bombing aside.

Its only a small point but a lot of ships were sunk using level bombing Blenheim's, Condors, Hampden's and a number of others were used in this role. If you include submarines lost by all nations to bombing the list is significant as low level bombing isn't skip bombing. I think you are talking about high altitude bombing in which case you are probably correct.

 

[Shortround6]

The 500KG of bombs in the rear bay was pretty much ten 50kg bombs, at least most (all?) English sources don't give a different alternative (pair of 250KG ?)

The JU 88 was a rather adaptable airplane but unfortunately a number of on-line sources ( or hastily produced books) tend to print MAX capabilities like range with full internal fuel without noting it. Or full bomb load on early versions was twenty eight 50kg bombs inside and four 100kg bombs outside, total 1800kg but the external stowage cuts into range/speed. Swapping internal bomb stowage for fuel and carrying bigger bombs outside boosts range and keeps bomb load up, or increases it but hurts speed.

I will readily admit I don't speak or read German (many of you who have suffered through my mis-spellings and typos are wondering about my English) but the two charts provided by Koopernic seem to be a bit off. Perhaps it is just me but using identical boost and rpm on the engines at 6000 meters and flying at just 10kph difference in speed the fuel consumption is listed as being 110 liters an hour different (only 82% of the fuel burn). At a given boost setting and rpm the fuel burn should be identical with the speed being the thing that changes due to drag/load. The plane with more drag/load may be able to "cruise" as fast as the lower drag airplane by using more fuel but unless the plane is shifting from lean to rich in order to do so I doubt it would be at identical rpm and boost.

 

[Juha]

The 500KG of bombs in the rear bay was pretty much ten 50kg bombs, at least most (all?) English sources don't give a different alternative (pair of 250KG ?) ...

At least the Ju 88 A-4, on which Ju 88 C-6 was based, could carry only 50kg bombs (or with special adaptors SD 2 "bundles", but IIRC that was stopped soon after 22 June 41 because of number of fatal accidents with SD 2s) in its bomb bays. 250kg SC 250 at least was too big for 88 A-4's bomb bays.

 

[Greyman]

Which Ju 88?

Here's the data I got in a hasty-photoshop chart:

The A1 is from 'Janes', not from a flight test.
The A4 is from a German wartime manual.
The A5 is from an actual British flight test.

Brown is a Sterling I, blue is a Blenheim IV, purple is a french DB7. All A&AEE performance trials. The DB7 wasn't fully loaded, other two were full load.

 

[Glider]

It makes the Blenheim look good

 

[mhuxt]

It makes the Blenheim look good

And the Stirling too - wouldn't have picked that. Are those 88s really at Notleistung / highest speed? Not trying to stir the pot, but slower than the Stirling?

 

[parsifal]

doesnt surprise me at all. German aircraft under combat loads and conditions frequently did not perform to spec. if for no other reason than there ere time when engine overhauls could be fewer and more widely spaced than in the allied camps

 

[Juha]

... It's worth pointing out that not a single ship was sunk by level bombers during WW2, skip bombing aside.

It's not because it is not true, level bombing wasn't very effective against moving ships but still sank ships now and then. And stationary ships were sunk from BB Tirpitz downwards.

The Ju 88 was used as a tank destroyer, simply using its dive bombing capability and the Stuvi 5B to do the job. A pair of 500kg bombs sufficed but the more skilled Finnish pilots liked to use a pair of SC-1000. The dive would commence at 8000ft, pull-up complete at 5000ft, speed reached 400mph, accuracy good enough to destroy a tank.

That was what pilots claimed but what really happened is more difficult to establish, anyway not the most effective way to kill tanks.