Evolution of the Henschel Hs 130

[rinkol]

Hi! I can't understand bottom one's concept. Someone please explain me. :-[

The bottom concept has a big additional "central compressor" (Z) that is driven mechanically by a separate third engine (M3). All the three motors (M1,M2,M3) have also their own small mechanical compressors (L1,L2,L3).

There is also an intercooler. The scheme has the attraction that the amount of available boost can be varied by throttling M3. It also seems relatively simple since it can be built up around existing engines, but for reasons that don't seem to have been documented, fell short in reliability.

 

[rinkol]

Thansk mz! Why are Z divided into 2 piece?
I can't imagine air pass from forward Z to after Z. :-[

The simplest interpretation would be that the central compressor is a single stage unit of centrifugal design. However, the labelling seems to indicate that there are two stages in this position. There could be two centrifugal superchargers in series, but the required ducting is not apparent in published photographs.

I have seen a suggestion that the central unit was based on Roots compressor concepts, but find it difficult to understand why such a design would be used.

 

[T. A. Gardner]

The interesting part of the Hs 130 was in it's evolution. The early A and B models were to be high altitude research and reconnaissance aircraft having a low priority with the Luftwaffe. Henschel was seen and treated as an upstart company by the RLM at the time, considered a late comer to aircraft and often dismissed as a competitor in high priority projects.
With the of the official entries in the Bomber B program from Junkers and Focke Wulf looking like they were in trouble being developed (the Arado and Dornier entries were nonstarters), the RLM belatedly turned to Henschel and asked them to redesign their Hs 130 into a bomber meeting that program's requirements.
Henschel designed a new fuselage to mate to the existing Hs 130 wings. The first Hs 130C bomber prototypes were ready by late 1942 and proved relatively fault free in testing. An initial series of 100 Hs 130C-1 bombers was ordered in mid 1943 but then cancelled later in the year due to the changes in Germany's strategic position where offensive high altitude bombing had become an unaffordable luxury. Thus, the Hs 130C became the only successful entry in the Bomber B program.
The Hs 130 D and E models were for high altitude reconnaissance. The HZ Anlage seems to be a work around for a turbocharger or turbo-supercharger system like the US employed on aircraft. It would have eliminated the need for high temperature ducting from the engine exhaust as well as allow a substantial increase in the size of the compressor used.

 

[newsdeskdan]

The Hs 130 D and E models were for high altitude reconnaissance.

The Hs 130 E was intended as the basis for a high-altitude bomber. It was offered in four-engine form (without the fuselage-mounted engine) as a competitor for the Ju 488 in August 1942 1943 and it lost primarily because Henschel had no capacity to develop it.
In its favour were the facts that prototypes already existed and that its wings would, apparently, need only minor modifications to accept an extra engine each. The Ju 488, while it was going to be made from some existing components, was still a 'new' aircraft.
It's stated in various sources that this four-engined Hs 130 would've been called the Hs 130 F. Nicolaus refers to an Hs 130 F in his summary of Henschel designs for the Allies in 1945 but doesn't say what it was. The various RLM meetings discussing the type refer to it as 'Hs 130 neu' or 'Hs 130 viermotorig'. It is always said to be a development of the Hs 130 E.

EDIT: That should say August 1943 not August 1942 - my typo.

 

[T. A. Gardner]

The Hs 130 D and E models were for high altitude reconnaissance.

The Hs 130 E was intended as the basis for a high-altitude bomber. It was offered in four-engine form as a competitor for the Ju 488 in August 1942 and it lost primarily because Henschel had no capacity to develop it.

That's the C model. The D and E were reconnaissance planes. In the E model the HZ-Anlage compressor installation and fuselage fuel tanks took up most of the space leaving a small bay just aft of the pressure cabin held three cameras. There was no internal bomb load and the two hard points on the inboard section of the wings were for drop tanks due to the fuel consumption issue.

 

[newsdeskdan]

That's the C model. The D and E were reconnaissance planes. In the E model the HZ-Anlage compressor installation and fuselage fuel tanks took up most of the space leaving a small bay just aft of the pressure cabin held three cameras. There was no internal bomb load and the two hard points on the inboard section of the wings were for drop tanks due to the fuel consumption issue.

I can see why you would think that - but the Hs 130 C was an earlier design, built as a high-altitude bomber in 1941. The design under discussion in August 1943 (sorry for the typo in my earlier post) was a project based on the Hs 130 E. The earliest reference I can find to it is from the Entwicklungsbesprechung of August 10, 1943, under the heading '3) Ju 188 / Hs 130 - altitude aircraft (4-mot.)'. It is stated that since the Hs 130 E is already due to enter production in limited numbers "it was investigated how an altitude aircraft can be created on the basis of the Hs 130 or on another basis that is as favourable as possible for procurement", which can be built with "really promising dates and number of units".
A full discussion then follows on August 20, 1943, with comparisons of possible armaments, altitude performance, range, etc. Both the Ju 488 and the Hs 130 were to have been equipped with 4 x wing-mounted BMW 801s. The Ju 488, it is said, would have a wing area of 84sqm compared to the Hs 130's 86sqm, but the Hs 130's existing 33m wingspan would mean (according to Henschel technical director Karl Frydag, who was present at the meeting) that it could accommodate the additional wing-mounted engines with only minimal changes. The Ju 488 could only reach its wingspan of 30.87m with newly designed and manufactured sections.
What we don't have is details of how the interior of the Hs 130's fuselage would be rearranged. The Ju 488 was to have a new fuselage 'bulge' to accommodate a decent-sized bomb bay - perhaps the Henschel design would have had something similar. Deleting the HZ-Anlage would have freed up some space at the centre of gravity.
Henschel had a lot of projects about which almost nothing has survived and this appears to have been one of them. That said, there will be a LOT more detail on the two designs and the discussions surrounding them, with full archival references cited, in my Secret Projects of the Luftwaffe: Bombers 1939-1945 book.