Rocs for Finland

[apophenia]

This is based on a suggestion by Sport25ing. During the Winter War, the British did promise Blackburn Rocs to Finland but, in OTL, these turret fighters were never delivered. Here, I just back-dated the delivery process a bit.

(Apologies, in advance, to perttime for my inevitable mangling of Finnish terms!)

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Blackburn Rocs for Finland's Ilmavoimat

The Blackburn Roc turret fighter probably seemed like a good idea at the time. Envisioned by the Fleet Air Arm as both a fleet defender and potential escort for the related Blackburn Skua fighter/dive bombers. But, by October of 1938, outright cancellation of the type was being considered. Production was allowed to continue - mainly to keep subcontractor (and turret supplier) Boulton Paul busy - but likely roles were shifting from fighter to target towing and similar second line duties. Operational units issued with Rocs often put in requests for additional Skuas with which to replace their unwanted turret fighters.

The indiscriminate Soviet bombings of the Finnish capital of Helsinki on 30 Nov and 01 Dec 1939, resulted in the deaths of more than 100 Finnish civilians. In response to a public outcry in Britain, the RAF and Royal Navy were ordered to draught schemes to donate aircraft to the hard-pressed Finns. Royal Navy planners had already been wondering what possible role might suit their overdue Blackburn Roc turret fighters. By the second week of December, it was decided that at least some Rocs should go to Finland.

The first tranche of ten Rocs for Finland came directly from Royal Navy stocks. Flown by British pilots, these aircraft flew in stages to Norway, across Sweden, before finally arriving at Tampere. There, VL refitted the Rocs to suit Finnish Ilmavoimat service. After test-flying, it was decided to improve the aircraft's mediocre performance by removing their heavy, bulky turrets. The 10 x Boulton Paul Type A turrets were transferred to Finnish Bristol Blenheim I light bombers. [1] Meanwhile, the first ten Rocs would receive he surplus Bristol Type B turrets removed from the Blenheims - these single-gun and manually-operated turrets being both much lighter and less 'draggy'.

The second tranche of Rocs were delivered directly to the frozen surface of Jukajärvi. Boulton Paul had fitted the first six of this group with fairings for an open rear gun position. Each was intended to be armed with a Vickers GO but these weapons were not included. In their place, the Ilmavoimat substituting available Lewis guns (in '7,70 mm x 56 R' for commonality with the ancient Blackburn Ripon biplanes that the Rocs would share an airfield with.

RO for Roc - Winter War Blackburn Bombers

The first 16 x Rocs were assigned to Lentolaivue 16 at Lahdenpohja to combat Soviet incursions north of Laatokka (Lake Ladoga). A typical mission involved a Ripon biplane flying as a scout. When Red Army columns were spotted and reported by wireless, Rocs were directed onto these targets. At first, Rocs offensive armament consisted of nothing but a pair of jerry-rigged wing guns and light bomb racks. As a result, the effects of LLv.16's attacks on Soviet columns was minimal. Immediately, work began on ad hoc armaments improvements.

Belly racks for heavier bombs was not a difficult modification but the Roc crew had no reliable means of aiming such weapons. Still, the bursting of 125 kg fragmentation bombs in their vicinity seemed to be having an effect upon Russian morale. More effective proved to be the locally-concocted 'kanootti' - a faired wooden landmine delivery system. Using these primitive dispensers, LLv.16 aircraft were able to strew a mix of anti-personnel and anti-vehicle mines in the path of the advancing units of the Soviet 139th Rifle Division.

Top Keltainen nro 1 (Yellow 1). A Blackburn Roc of the first tranche fitted with a Bristol turret and armed with a 'kanootti' (canoe) belly-mounted landmine dispenser. Mid-January 1940. This aircraft was damaged by 'friendly fire' over Läskelä (now Lyaskelya) on 04 Feb 1940 and sent to VL at Härmälä for repairs.

As the Soviet offensive in Eastern Karelia stalled, the aircraft of LLv.16 were focused on the Kollaa Front. While the squadron's Ripon's performed nocturnal attacks (targeting Red Army camp fires), the Rocs were increasingly used for reconnaissance flights over Soviet lines. This was facilitated by field modifications for low-altitude, cable-operated cameras mounted in the belly.

Bottom Punainen nro 3 (Red 3). A Blackburn Roc of the second tranche sporting the 'BP' fairing for the rear cockpit. The original camouflage has been overpainted with a Talvi maali scheme of water-based white paint. This seasonal camouflage was considered essential for low-level photo-recce missions (although note that this Roc still mounts small-bomb wings racks as well).

(To be continued ...)

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[1] Ten Blenheim Is were selected to receive 'turret transplants'. The Blenheims were modified to accept the heavier Boulton Paul Type As, thereafter acting as 'escorts' - those 4-gun turrets providing a nasty surprise for any Soviet fighters coming up behind a formation of Blenheims.

BTW: The images were modified from combined versions of images from:

Blackburn B-25 Roc (1938) on Naval Encyclopedia
-- https://naval-encyclopedia.com/naval-aviation/ww2/uk/blackburn-roc.php

And nag's Gallery: http://www.nags-gallery.com/gallery/roc.htm

[apophenia]

Last of the Line - Continuation War Blackburn Rocs

One second tranche Roc was retained at Härmälä by the Valtion lentokonetehdas (VL, the state aircraft factory). This aircraft - RO-18 - had been damaged at the end of its delivery flight when heavy braking resulted in this Roc nosing over on landing. During the Winter War, RO-18 was raided for parts to keep the rest of the fleet airborne. However, in the Summer of 1940, VL restored this airframe to airworthiness to employ it as a test mule for Roc modifications.

Even before its restoration, Roc RO-18 served to ground-test the fit of what became known as the VL kuomu (or 'VL hood'). (Despite the popular name, this canopy was actually produced and installed by the Karhumäki brothers' factory in Kuorevesi.) It was a simple structure of sheet metal and curved sheets of perspex. To its rear was a short, sliding section with triangular flaps to help shield the gunner from the slipstream (essential during Winter flying but also aiding the gunner's aim by reducing buffeting).

Returning the damaged aircraft to the air dictated the installation of a new engine. But this revealed a problem since Finland could no longer import aero-engines for the UK. The sleeve-valve Perseus was a 'widow' type for the Ilmavoimat - powering only the Roc. Eventually, lack of engine spares would ground the fleet if alternatives could not be found. The obvious replacement engine type was the similarly-sized Bristol Mercury. Alas, the Ilmavoimat had already assigned priority for limited stocks of PZL and Bristol Mercury engines to VL fighter production and keeping the Blenheim fleet aloft.

'Alkonost'? - The Russified Rocs

As a temporary measure, to get RO-18 airborne again, a Soviet M-62 radial was installed. Recovered from the remains of a Polikarov I-153 fighter shot-down during the Winter War, the M-62 was thirstier and had a larger displacement but, dimensionally, the Shvetsov engine was actually slightly more compact than the British sleeve-valve engine. The Soviet radial produced more power for take-off - which was welcome on Finland's rough airfields - but, at typical low- to medium-altitudes, output was much the same as the Perseus (albeit at lower rpms).

Top RO-18, a Blackburn Roc from the second tranche acting as a VL 'mule'. The aircraft is seen here in the Winter of 1940/41 fitted with a 'VL hood', Shvetsov engine, and an experimental, fixed ski undercarriage. Note that, here, RO-18 is also testing a 4 x wing gun installation.

At this stage, RO-18 - a very early production Roc Mk.I - still wears the overall silver dope finish that it was delivered in. (It would later be refinished in the standard Ilmavoimat scheme of dark/green uppers and blue undersides.) The VL logo is carried on the tail fin.

The Shvetsov M-62 was a Soviet development of the US Wright Cyclone. Such was the success of the M-62 installation that VL initiated efforts to source similar or related engines for the Rocs. In the meantime, delivery of the third tranche of Rocs had been truncated by the ending of the Winter War. Of the 33 Blackburn airframes promised to Finland by Britain, only 27 had been received. Of those, six Rocs had been destroyed in combat during the Winter War, RO-18 (as already noted) was damaged upon delivery, and another half dozen were awaiting major, depot-level maintenance or repair.

The final half-tranche of Rocs were delivered like the tail end of the second tranche - turretless but with no changes introduced to make these aircraft fully useable in combat. Those ten airframes were all given similar modifications - denavalization, 'VL hoods', 4-gun wing armament, and Finnish-specified equipment fitted - included bomb racks. However, such were the demands on VL during the Winter War that none of the final ten Rocs would be made operational before the end of that conflict.

Through the early stages of the Jatkosota (Continuation War), VL and frontline units sustained an ongoing modification programme for the Ilmavoimat's surviving Rocs. Available aircraft were detailed to the Eastern Karelian front and over time introduced improved armaments while standardizing on the Shvetsov M-62 engine (most being procured from German 'war booty' stocks). Wing gun armament mods were dependent upon available stocks. Most updated Rocs had 4 x wing gun (usually 7,62 mm ShKAS) or twin 20 mm ShVAK autocannons with 7,62 mm Degtjarev DA machine guns in the rear cockpit (again, most gleaned from stocks captured by the Germans).

Bottom A Jatkosota-era Blackburn Roc from the third tranche. Redelivered in ate 1941, RO-24 features many of the upgrades expected of an Ilmavoimat Roc - M-62 engine, cannon wing armament, etc.

Issued to Täydennyslentolaivue 17, here RO-24 mounts a captured Soviet FAB 250 general-purpose bomb on its Finnish-designed belly rack. This aircraft served with Täyd.LeLv 17 until the beginning of April 1942 when she was lost to ground fire during the Red Army assault across the Svir River.

[Sport25ing]

Just as I thought, a excellent result 

[MAT]

Four of the 20 Blackburn Rocs for Finland, at Dyce march 13, 1940. The Winter War ended on the same day and the Air Ministry stopped all deliveries.

[GTX_Admin]

 

[perttime]

The Roc isn't exactly pretty.... but if it does a job that needs to be done 

[Buzzbomb]

Great work on those.
One of my favourites from the early WW2 FAA stable.

With skis... love it
Now if you really want to slow it down.. put floats on it 
The FAA found that out quite quickly.

[apophenia]

Thanks folks!

Four of the 20 Blackburn Rocs for Finland, at Dyce march 13, 1940...

Cheers MAT    So, RO-143 was a real serial ... wonder where they got that number from?

... Now if you really want to slow it down.. put floats on it ...

    Yup, a mutt wearing galoshes    The skis gave me a chance to cant the undercart forward a bit (hopefully, reducing the Roc's penchant for noseing over!).

[MAT]

Four of the 20 Blackburn Rocs for Finland, at Dyce march 13, 1940...

Cheers MAT    So, RO-143 was a real serial ... wonder where they got that number from?

The serials of the Finnish Air Force were a bit messy. It consisted of two letters for the type (Blackburn Roc was RO-) and a individual number. The know serialnumbers for the Rocs are RO-141, RO-143, RO-147 and RO-150. The FAF liked to begin the number sequence with xx1. So for the 20 Rocs the numbers would probably have started with RO-141 and ended with RO-160.
BUT!
The numbers  -141 to -160 were already in use on the Blackburn Ripon IIF (RI-). And in general the FAF didn't mind to have the same number used by different types. -129 was used on a Bristol Blenheim IV (BL-129) and on a Fokker D.XXI Sarja IV (FR-129).

[apophenia]

Thanks for the details, MAT.  So, I was way off going back to '1' to start my serials! Oh well, ...

[Dr. YoKai]

 I really like the land mine dropping fit.

[apophenia]

Cheers Doc! I had fun building something out of Finnish birch plywood 

A landmine dispenser seemed like a useful idea ... although I'm not sure how practical this concept would have been in 1940. Nor do I know when insensitive explosives were first developed. So, maybe at the time some kind of bang-on-impact munitions dispenser would be more realistic?

[Old Wombat]

Lots of various time-delayed munitions deployed during WW2, so the explosives must have been reasonably stable.

[apophenia]

Lots of various time-delayed munitions deployed during WW2, so the explosives must have been reasonably stable.

Thanks Guy. So, that suggests the basic idea could work ... but perhaps with purpose-designed mines (or fuses) rather than off-the-shelf.

[Dr. YoKai]

 And God only knows how many UXBs are still waiting under the soil here and there...the only thing I would wonder about would be how effective an air-dropped land mine would be-seems like the traditional method of burying them for concealment wouldn't work to well. In winter, with white paint?

[Old Wombat]

I'd recommend a penetrator type bomb, designed to punch an approximate depth into the ground (I don't think roads or other paved areas would be suitable, but I could be wrong), with the impact arming the mine trigger, which would probably be either pressure or magnetic (I don't know if there were vibration activated mines during WW2 but there were such systems to prevent defusing of bombs, etc., which must have been able to survive the impact of a bomb with the ground).

[apophenia]

I'd recommend a penetrator type bomb, designed to punch an approximate depth into the ground (I don't think roads or other paved areas would be suitable, but I could be wrong), with the impact arming the mine trigger, which would probably be either pressure or magnetic (I don't know if there were vibration activated mines during WW2 but there were such systems to prevent defusing of bombs, etc., which must have been able to survive the impact of a bomb with the ground).

Penetrators would definitely be an advance in technique ... but paved roads bring up a local conditions issue. In 1939-40, paved surfaces would have been hens' teeth in rural Finland. Most roads through Ladogan Karelia would be hard-packed dirt and gravel.

Hard though they are, such roads are still semi-permeable. As a result, Autumn rains seep into the soil and then freeze packed-ground solid with the advent of Winter. Then the snows start.

Once there was sufficient snow on the ground and falling, aerial dispersal of area denial weapons would be simplified. Snow cover slightly cushions the impact of falling munition which are then covered by falling snow. No burial is required. Advancing armour (or logistics) can't see those scattered mines for the snow cover anyway.

[apophenia]

And God only knows how many UXBs are still waiting under the soil here and there...the only thing I would wonder about would be how effective an air-dropped land mine would be-seems like the traditional method of burying them for concealment wouldn't work to well. In winter, with white paint?

Too true, Doc.

For current times, check out the amazing work being done by groups like Menschen gegen Minen, Golden West, Mines Advisory Group, HALO, animal specialists APOPO etc. MgM was way ahead of the wave on the mineclearing potential of MPVs. MAG is effective enough at humanitarian demining in Ukraine that Moscow has targetted their deminers by name! And APOPO? Well, who doesn't love African giant pouched rats?

As for the whif Finland concept, as mentioned above, snow does most of your concealment work for you. But, it lead time permitted, white paint on mines would certainly be worthwhile.

[perttime]

Air dropped anti-personnel mines would be nasty to your own troops too, assuming you hope to use the area later. Anti-vehicle mines possibly too. I like the idea of bomblets against soft enemy formations better.

Finland isn't always snowy. Dropped munitions might sink a bit into muddy roads too.

[apophenia]

Air dropped anti-personnel mines would be nasty to your own troops too, assuming you hope to use the area later. Anti-vehicle mines possibly too. I like the idea of bomblets against soft enemy formations better.

Finland isn't always snowy. Dropped munitions might sink a bit into muddy roads too.

IIRC, it accepted that Finland would have to fall back north of Ladoga in order to concentrate resources on the Karelian Isthmus. That said, you're right. Any counterattack along mined roads would be made much more difficult.

Agreed too on bomblets. But I see the Roc as a big, fat target largely lacking in armour protection and defensive armament ... more 'sitting duck' than giant raptor. So, my notion was to 'seed' the roads ahead of the Soviet advance. With luck, Red Army sappers will have cleared all those roads in the months between the end of the Winter War and July 1941 push to liberated Eastern Karelia.

On snow: I read years ago that Winter 1939/40 was especially cold and snowy in Finland. Any idea if that claim is true?

[perttime]

...
On snow: I read years ago that Winter 1939/40 was especially cold and snowy in Finland. Any idea if that claim is true?

It was cold but not exceptionally snowy. Cold air is dry, so there is less possibilities for precipitation. Snow in winter is business as usual.
- December 1939: temperatures varied but, on average, the month was a couple of degrees colder than usual.
- January to March 1940: a strong high pressure area around Greenland and the Norwegian Sea pushed cold air towards Finland, and temperatures mostly remained several degrees lower than usual. Many places in southern parts of the country had record lows. Especially Soviet troops from the Ukraine didn't cope well. There were fewer clouds than usual.

https://en.wikipedia.org/wiki/Battle_of_Raate_Road

The following winters until 1942 were also colder than usual.