Hello, and welcome to Aviation Deep Dive The Blohm & Voss BV 155 was an experimental
late-war German interceptor designed principally to counter the threat of USAAF B-29 raids
on Germany. Sporting an extreme design in order to come to terms with extreme design
requirements, the 20 metre wingspan would keep the Daimler Benz DB 603 running at 1,400
horsepower up to an astonishing 15 km of altitude. To understand the circumstances of this aircraft,
and what led to the design criteria that produced such an odd and unique layout - we have to head
back to 1942. Although the BV 155 would ultimately end being a reactionary aircraft to the alarming
B-29 (which is pretty much what the Ki-87 was, the aircraft we covered in the last episode), it’s
roots are actually quite substantially different. In the Spring of 1942 work on the
prospective German aircraft carrier Graf Zeppelin was well underway,
and so the RLM began looking at specifications for aircraft that would
be capable of carrier operations. With a navalised Stuka on the cards, the logical
need for a carrier based fighter led to talks with numerous German aviation companies about
a suitable aircraft for the job. Messerschmitt, the golden child of the Luftwaffe with their
109, was only too keen to propose the Me 155. For all intents and purposes the Me 155 was
essentially to be a significantly modified 109, a replacement for the previously attempted
109T. It would use as many parts as possible in common with the standard 109 G in the
interest of streamlining the transition to mass production, and would essentially
keep the fuselage, with entirely new wings. The infamous landing gear too, would be
altered to an inwardly retracting design which would of course be much safer
for carrier landings, which are pretty difficult to begin with - let alone trying
to do it with narrow track undercarriage. The design was looking quite promising, to be
powered by 1,500 horsepower DB 605 and with a proposed armament of three MG 151s and two MG
131s - but ultimately as the Graf Zeppelin project ground to a halt in late 1942 after an order from
Hitler that all of the large Kreigsmarine vessels should be scrapped - the usefulness of the Me
155 project essentially became zero overnight. The entire design process had been
completed in September of 1942, almost exactly after which Messerschmitt were
informed that the design would no longer be of any use, and they should shelve the
design for the foreseeable future. Messerschmitt was understandably pretty annoyed
that they’d just essentially put all of the design work into an aircraft for it to be shelved
immediately after completion, so it was decided to try and repurpose the design - to a different RLM
specification for a high speed tactical bomber. Working quite quickly, all the
naval equipment was to be removed, the central fuselage section strengthened
and the tail wheel elongated to give enough ground clearance for the 109 to take off with
a 1,000 kg bomb installed on its bomb racks. Designated the Me 155A, although a pretty
intriguing design, the RLM was apparently having none of it, and it was rejected
almost immediately after it was proposed, leaving Messerschmitt disgruntled with
a useless design at the end of 1942. However, scarcely a month later, the RLM once
again reached out to Messerschmitt with a new, more important proposal. The end of 1942 did
not just mark the end of the Graf Zeppelin, it was also when the Boeing B-29
took to the skies for the first time, and news of this technological advanced,
high speed, high altitude bomber didn’t take long to send shockwaves through
the Luftwaffes chain of command. The RLM needed a counter, and quick, it was
unknown exactly how long it would take for the B-29 to hit operational squadrons in Europe, but
it already had a pretty significant time advantage over whatever counter the Luftwaffe would be able
to muster. Of course, what the Germans didn’t know is that the B-29 was envisaged far more as a
bomber for the Pacific theatre than for the European theatre, but nevertheless Messerschmitt
was given the requirement to urgently develop a high altitude bomber interceptor - capable
of speeds and altitudes far exceeding what their current fighters were comfortably
operating in, with heavy armament to match. Once again the engineers at Messerschmitt went
to the drawing board. As it was an urgent task there wasn’t a realistic chance of coming up a
design from scratch in the expected time frame, so they once again turned to the Me 155 idea
and began modifications - which, at this point, was still essentially a modified Bf 109G. The
wingspan was increased significantly to 13 metres, a pressurised cabin was installed, and an
elongated engine nacelle to fit the DB-628 engine. The DB-628 essentially being a DB-605 but
with a two-stage supercharger and an intercooler. In early 1943 a 109G was modified to the new
spec, designated Me 155B, and underwent its maiden flight. In testing, the aircraft reached
a maximum altitude of 15,500 metres and was all around promising, but the RLM realised that
the DB-628 was not ready for production, only about 50 had been built - they considered
that it would move along the project considerably to fit an engine already in mass production - and
just add on a turbo-supercharger instead. As such, it was ordered to Messerschmitt to abandon the
DB-628, and refit the Me 155B with a DB-603 paired with a TKL-15 turbo-supercharger. Accordingly,
the frontal fuselage was further elongated, and work continued on modification until August
1943 - when the Technical Department of the RLM decided that Messerschmitt was too busy with
developing the 109 and it’s planned successor. They didn’t want to overload Messerschmitt
and compromise on fighter production. As such, the project was forcibly removed from
Messerschmitts hands and put at the doormat of Blohm & Voss, who were considerably less
busy. However, after a preliminary analysis of the aircraft, Richard Vogt (Chief of
Design at Blohm & Voss), concluded that the Me 155B was a fairly weak design and
it would preferable to start from scratch. The RLM was against this, of course, as it would
significantly delay the project - and so set up a shaky agreement between Messerschmitt and Blohm &
Voss that every major design change suggested by Vogt would have to be sanctioned by Messerschmitt.
This deal fell through almost immediately, as the relations between the two companies
plummeted as Blohm & Voss wanted enormous changes to the design, whilst Messerschmitt was
extremely unhappy with the proposed alterations. Ultimately, Richard Vogt gave up on Messerschmitt
and wrote directly to the RLM, saying in a letter This came to a head after a series
of hostile meetings between the lead designers at Messerschmitt and
Blohm & Voss, whilst officials from the Technical Department tried to act
as intermediaries and calm the situation. Ultimately, they went nowhere, and the
RLM ruled in favour of Blohm & Voss, and gave them full control of the development and
design of the aircraft from that point forward. As such, until the end of 1943 the Blohm &
Voss committed themselves to a fairly thorough redesign of the aircraft, which eventually
ended up as the renamed BV 155 V1. A pretty significant departure from the Me 155, the new
design featured landing gear based off a Ju 87, an all-new fuselage, a completely re-designed
laminar flow wing - as well as a hefty internal fuel capacity of 1,800 litres (or 475 gallons),
and the very distinctive underwing radiators. However, it had been over a year since the
catalyst for such an interceptor had taken to the skies, and construction on this aircraft
hadn’t even begun yet. Over the course of 1944 assembly began, but the constant allied bombing
caused significant difficulties to Blohm & Voss, who found themselves constantly having suppliers
drop out of the equation and batches be cancelled. As such, it would be a painful 9 months
until the laborious construction of V1 was finally completed. Of course, by now it was
September 1944 - the war was essentially over, and the Luftwaffe had needed a high
altitude interceptor in huge numbers, piloted by skilled crew members,
many, many months before. Nevertheless, the newly finished 155 V1 was
still a fascinating piece of technology, taking to the skies on the 1st September
1944. Powered by a DB-603A engine, the turbocharger would keep power up to an
astonishing 1,450 horsepower at an altitude of 15,000 metres (or 50,000 feet). The aircraft was
also fitted with an MW-50 boost system, allowing temporary periods of higher manifold pressure, and
significantly higher power, by spraying a mix of water and methanol into the supercharger.
However, it was not all smooth sailing. Some significant shortcomings involved the
radiators not offering sufficient cooling at takeoff or at high angles of attack,
which resulted in the DB-603 overheating badly at certain critical stages of
flight such as takeoff and landing. Incorporating larger radiators as well as some
other minor alterations to the canopy and tail, the V2 was finished in early 1945 - which
would have been considered a prototype for the production run. However, the engineers at
Blohm & Voss were not particularly happy with how the aircraft had turned out, and even
before the V2 had taken its maiden flight they proposed a revised version to the Technical
Department which would be powered by a DB-603U, with a supercharger and a different gear
ratio for the four bladed wooden propellor. A number of armament setups were considered,
all of them fairly heavy to deal with the huge American bombers - consisting of a mix and match
of three 30mm Mk 108s, 103s and 20mm MG 151/20s, though ultimately none of
the prototypes were armed. Considering that it had become obvious by this
point that the B-29s were not really being used, it’s somewhat surprising that the RLM
sanctioned Blohm & Voss to begin work on a new variant instead of tinkering with
the V2, but once they got the green light the BV 155C was given an order for 30
aircraft once production had begun. The 155C would differ significantly,
ditching the underwing radiators for a more traditional central annular radiator,
more inline with aircraft such as the Ta 152. Meanwhile, the 155 V2 had
run into trouble elsewhere… The crash landing was well executed, and ultimately didn’t damage the airframe too
much, but the attempted salvage operation, which involved wrapping chains around the
aircraft and towing it out with a truck, ended up inflicting so much damage to
the aircraft that it was irreparable. The subsequent V3, developed alongside
the ideas for the 155C series, was essentially like the V2 except that
it was to be fitted with a DB-603U - the engine intended for the 155C series -
but it was ultimately only half finished by the time the end of the war rolled
around - and it’s fate remains unknown. V1 and V2 were both captured by advancing
British troops and subsequently flight tested at the hands of the RAF back in England,
V1 being flown until it was written off. V2, still damaged from its salvage attempt, was put into storage, where it still resides at
the Smithsonian National Air and Space Museum. It had become obvious long before the end of
the war that the BV 155 was an answer to a problem that was almost 3 years out of date by the
time it was approaching readiness of production. The entire concept had originally been a quick
interceptor based on an existing design in late 1942, but somewhere along the way - with delay
after delay - the RLM accepted a brand new design to begin work, which began as late as
December 1943 - undermining the entire point of the project. Ultimately, the BV 155 was
a fascinating look into late war technology, sporting a bizarre, experimental design,
but that would end up suffering the same fate as most German aircraft from
1944 and 45 - too little too late. A huge thanks to my Patrons, on screen now,
for supporting the channel and Thankyou so much for watching this video of Aviation
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