[leonventer]

Hi Birgir,

Originally Posted by Birgir Thorisson

4) Could the Ju 87R carry 500kg bombs?
5) Could the Ju 87 carry 1000kg bombs?
6) Could the Ju 87B trade off bombload for range. (i.e. carry external drop tanks?)
7). How long would it take the Stukas to arrive over the carrier at attacking height (I have seen both 12000 feet and 16000 feet mentioned), from the moment the incoming strike was detected on Radar?
8) What was the radius of action of the Stuka?

Back in Feb 2002, Les Whitehouse submitted the three posts below about the differences between the Ju 87 B and R variants.

Hope that helps,
Leon Venter

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Ju87R - Les Whitehouse 13 Feb 2002
The reason for the classification of B-1 = R-1 and B-2 = R-2 was probably based upon engine. In actual fact the two types B-2/R-2 were built in parallel on the production lines at Weser only a few being later conversions so the serial numbers intermingle. All R aircraft had an enlarged (or additional?) oil tank in the fuselage over and above the two 300 litre drop tanks so they carried extra fuel and oil. They also had a dinghy and survival equipment etc.

The main rack capacity was changed between the B-1 and B-2 from 500 kg (500 XI B rack) to 1000 or 500 kg (1000/500 XI B rack). A similar capacity existed between the R-1 & R-2. Although the carriage of a 1000 kg bomb in anger was rare, photographs exist of both R-2 and B-2 with such weapons in use. Also remember the bomb load was potentially reduced anyway as the addition of external fuel removed the ability to load the wing bomb racks. In some cases the early R’s appear to have sacrificed any wing bomb capacity by having what look like “rackless” or “half-rack” installations with simple struts. In the main however, most R’s photographed appear to have had fitments which linked to basic 50 kg racks, suggesting they could convert and operate like normal B’s where range was unimportant. In essence, at short ranges, there was no deterioration in bomb load capacity on the centreline rack

The R-1 (like the B-1) used the Ju211A engine
The R-2 (like the B-2) used the Ju211D engine
Others:-
R-2/trop – Ju211D engine and enlarged sand filter
R-3 - Ju211D engine but fitted for glider tow and having radio equipment which could be linked through the tow cable.
R-4 used the Ju211J engine like the 87D and had modified inner wing structure similar to the D series to take self-seal tanks. It also probably had the /trop filter as standard.

The major trade-off on the B to R saga was in fuel load+bomb load vs range to target and return - with the airframes constantly reducing fuel load/all-up-weight. Its total of fuel load and bomb load could not exceed the gross weight limit and it had to reach the target chosen. Hence if you wanted max range you had to reduce the bomb load. This and the target would dictate the bomb load on any mission.

R speed was 320 km/h compared to 340 km/h for the B
R climb to height was 16 min compared to 7 min for the B
R average range was 1210 km compared to 850 km for the B (could be improved by leaving out armour) but in order to use this range you had no underwing bombs and probably only a 250 kg centreline load.

If we look at weights based upon Junkers own figures, which are also not directly comparable because of variations in armour plate etc:-

Basic Weight B-1 2750 kg, R-2 3450 kg
Gross Weight B-1 4300 kg, R-2 5600 kg
(The B-2 had trial tests up to 5500 kg gross)

The B had 480 litres of internal fuel in two 240 litre tanks. The R added to this with two external 300 litre tanks only. The R-4 had the D inner wing structure so as to use its self seal tank design but still only had 480 litres internally and 600 externally. There is some confusion in early writings about internal tankage which confuses the R tankage with that of the D series. This type (D) had the same inner wing tanks but also an auxiliary 150 litres in each outer wing (480 + 300 internally) and usually the capacity to take a 300 litre tank under each outer wing also – hence a “long range” version of the D, for example, was inappropriate.

For your information – noting the replies about fuel weight - the Luftwaffe staff RLM GL/C B2 at the time used a fuel weight conversion of 0.74 kg/litre for their data charts – this is taken from a GL/C B2, Bf110 equipment and range datasheet. I have not ever seen a similar datasheet for the Ju87 B or R but one would certainly have existed.

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Ju87R Sources - Les Whitehouse 14 Feb 2002
Best published source is the Ju87 Stuka by Griehl – German edition by Motorbuch Verlag 1998, English Edition by Airlife 2001 ISBN 1 84037 198 6.

RLM Development Bureau Programme C listed all planned R production at Weser Aircraft.

B-1’s by Weser were planned 1937 through to March 1940 and B-2 production was to cover from July to October 1940. In parallel from June 1940, Weser were also tasked with the R-1 (presumably because they could then use the existing B-1 tooling with additions for the R-1?) and were tasked with delivering these July to October 1940 as well. R-2 production was intended to follow on from the R-1 once B-2 production was completed. In reality by that time not only had all the R-1’s been completed but a further qty of 123 R-2’s had been completed in advance of the original programme - presumably because the various sites used by Weser, including the opening of Berlin-Templehof allowed an expansion of throughput on the Ju87 B and R.

Note: there is photographic evidence of R-1 in service as early as April 1940 even in Greihl’s book (captioned as an R-2) and the first operational R-1’s were used in Norway – so Weser production appears to have been in advance of formal order documents and planned programmes

Rest of the data has come from my own research on serial numbers etc., but everything I have said is collaborated in Griehl’s account. Although, to be honest, it is not laid out as clearly and tankage in particular has to be pieced together from separate sections to get and overall picture of the changes. It is also not in his usual style and does not have production or loss lists like his He177 book. Griehl actually states a 1941 publication date for the Rechlin produced data table for the R-2 but does not publish the table. Griehl also confirms that, because of the engine type and component standards, the R-1 was “in effect” a long range B-1 and the R-2 a long range B-2, but as the R-1 came in during the latter half of B-1 production it had (as did the late B-1) the later style full exhaust stacks.

One other publication I could refer you to is the booklet “Stuka – Ju87” by Richard P.Bateson, Ducimus Books, 1972. However, not only would it be difficult to find a copy, it is simply a good historical account with lots of photographs. It has little on the technical side once past the prototypes, so would probably be a waste of effort. In this one the modified fuel system (R-4) is reported only as a modified "lubrication" system.

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Range - Les Whitehouse 15 Feb 2002
Range figures can be confusing. Some records/writers will quote a figure which is an actual “radius of action” - Allowing the machine to reach its target and return. Others will quote a straight line range, presumably on the basis that the aircraft will land at its destination. In most cases the data is incomplete unless all of the conditions are known. Ie: the weight (including crew, ammo, fuel and bombs), height and speed flown (hence rate of fuel usage). Unless all of this information is considered then calculations will be inaccurate and at best a prediction.

For your information:

There were formulae developed pre war for design approximations which allow both a crude prediction (UK - spot air range) and a more accurate prediction of range (UK – optimum performance range) to be made based upon the type of airframe (its drag efficiency), fuel consumption, airscrew efficiency and ratio of airframe and disposable load. I have had good correlation between these formulae and RLM documents applying the formulae to situations with the Bf110 (such as the flight by Hess). However the application is not easy and uses a lot of approximation (that’s technical for guessing!). At Boulton Paul the problem of a consistent basis of performance prediction and comparison with other manufacturers was so frustrating that they introduced a term in their proposals known as “reinforcing range”. This was the clear “non-radius of action” situation where extra tanks were fitted and the aircraft was simply to fly a basic route and land away from base – ie: reinforce a distant base.

Fortunately, in this case, we are concerned with data which has already been obtained from technical sources and a simple sum will clarify the loading conditions of the R Airframe.

Loads:

The following range figures were reported by Bateson in the Ducimus Publication but because they are in English figures it is not known if they are the result of tests on captured aircraft or taken from German documents. I have converted back to the SI system. They look to me like typical Rechlin/RLM style altitudes and the speeds are typical of optimum cruising speeds at the time for what were termed clean, low-drag monoplane airframes like the 109/110/87 etc. so I think they have come from “official” RLM sources. This is further backed up by the presentation style of two maximum weights:-

R-1 1429 km at 270 km/h outbound, 324 km/h inbound at 5000 m altitude

R-2 1254 km at 290 km/h outbound, 330 km/h inbound at 4000 m altitude

The speed difference inbound and outbound suggests a “chosen” load for the tests but that load is not specified.

The max weight limit of the R-2 was stated as 4700 kg stressed to H5 (full aerobatics) and 5650 kg stressed to H3.

Using these and Junkers “empty” limit for the R-2, I have calculated weight in Kg, based on Air Ministry style summation, assuming all disposable load plus weapons and radio are added to the empty weight:-
Basic 3450
Crew 180
Radio 160
Oil 45
Maps etc 2
3xMG17 38
1500 rounds 90
Fuel 799
Total 4764

250 kg bomb +250
Total 5014

This suggests to me that the airframe is overloaded by more than 300 Kg on take-off for the full H5 stressing. It would have had to use up at least 2/5ths of its fuel before it could dive bomb a target.

500 kg +500
Total 5264

This suggests ok for H3 stressing but the aircraft would have to be down to 4700 Kg before it could actually dive bomb a target (over 2/3rds of its fuel load). This would be unrealistic at maximum range as it could not return to base.