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VALMET Sk19 Vind  -  (Potez) CM176 Zephyr II

The story which didn't happen ... outside Atlantic Air Combat
 

By end of the Korean War, it had became clear for Sweden that more trouble was looming up in Europe, especially with the USSR going ahead with their plans to build up a fleet of aircraft carriers.  While the Baltic is not exactly a place to safely operate a carrier, it does offer additional air capabilities to reach out at sea and protect the mainland

But in addition of offering addtional assets on their Eastern flank, Sweden saw the potential danger also coming from the North with Soviet troops coming through neighbouring Finland or even Norway.  Also, an increasingly strong and potent Soviet Navy was a clear threat to Sweden's shipping lanes in the Artic and North Seas (Norway, Scotland, Iceland) and accross the Atlantic (Canada, United States).  So, while the debate had been going on for some time

regarding whether or not to scrap, maintain or develop their "blue water" navy (re: the three Sverige class, and the two Tre Kronor class cruisers), Sweden eventually decided early 1956 to strengthen their navy, and acquire aircraft carriers with the main purpose to enhance their anti-shipping capabilities in the Artic, and, to a lesser extent, provide a platform for anti-submarines aircrafts.  This decision lead to the A2 HMS Gotland and A3 HMS Lappland, the story of which is covered elsewhere in these ... fantasy Notes.

Although not identified initially, the need for a carrier capable trainer was soon realized.   With neither the rebuilt A21JN Gam, nor the J21AN Angripare being available in a trainer version some aircraft was necessary to allow a smoother conversion to naval air operations.  Only few aircrafts of the type had been or were produced, and none would be available second hand.   In fact both the T1A SeaStar nor the T2A Buckeye could not be made available before several years, so they were not considered any further, and the Potez CM176, a derivative and a mix of the French CM170.2 Super Magister and the naval CM175 Zephyr was chosen to be produced under licence by Valmet in Finland.  Within the Flyvapnet, it was designated Sk19 Vind

Trainers CM175 Zephyr CM176 Zephyr II T1A SeaStar T2A Buckeye Athena.T1

Engine(s) 2 x Marboré II 2 x Marboré VI 1xJ33 1xJ34 1xDart
2 x 400 kgp 2 x 480 kgp 1 x 2450 kgp 1 x 1544 kgp 1 x 000 ehp
Armament - 2 x 7.62mm/200rpg
- 2 x 110lb
- 2 x 13.2mm/175rpg
- 2 x 1100lb
2 x 12.7mm possible
2 x 500lb
- gund pod
2 x 500lb
- =
- =
    
There was a secondary reason to retain the type.   As Finland could only operate a limited number of fighter aircrafts, but an unlimited number of trainers, they had acquired 80 CM170 Fouga Magister.   Adopting the CM176 would allow Finland to easily operate the type along their own CM170 version, should the need arises.

The CM176 Zephyr II differed slightly from its predecessor.   At first glance, it looked like a standard CM170 Magister, thus retaining the standard canopy arrangement, equipped with the stronger landing gear of the CM175 Zephyr, and with Martin Baker Mk4 ejection seats.  While the sliding canopy of the CM175 did make sense, the standard one was nevertheless retained to speed up production with Valmet.   The CM176 was different enough in many aspects without having to manufacture a completely different canopy arrangement - a concession of the Swedes to their friendly neighbour.   Naturally the Zephyr II was thorouhgly protected against the corrosive marine environment. but differences were thus deeper.

First, it was powered by pair of the stronger Marboré VI engines, offering a welcome 20% thrust increase, and the wing tip tanks selected was the larger 230 l type relinquishing the smaller 125 l version.  While Potez was only going half way in marinizing their original design into the CM175 Zephyr but maintaining the same wing, the CM176 Zephyr II enjoyed folding wings, allowing the aircraft not only to land and take off from the new carriers but also to fully operate from them even if the folding system was a simple manually operated one.   While only lightly armed, its compatibility with the carriers elevators made it part, at least potentially, of the carrier air wing rather than a passing visitor.

Its armament was similar to their predecessor, with two wing pylons offering provision for a 110lb bomb each, or rocket launchers (either 18x37mm or 6x70mm), and HVAR rockets under the wing, the latter being fired from specific individual rails rather than stacked in vertical pairs like the French T10 arrangement.  A pair of nose mounted machine guns was retained, but with AKAN 13.2mm (175rpg) in lieu of MAC AA52 7.62mm ( 200 rpg) guns.  A tight fit with deeper ammunition cases being intalled lower in the nose.   With the AKAN guns being significantly longer than the MAC ones, the barrels were ungainly protruding from the nose.   While a slightly heavier installation, the weight shift was partly balanced by the arresting gear installation, itself a different design compared to the French original.  Anyway, ammunition standardization was a concept the Navy had insisted on.

Gun Cal Rpm Shell HE Range Weight Rpg Total










Akan.M44

13.20x99mm 

900

42 grms

8 grms

2000m

25kg

175:7.35kg 64.7kg

MAC.AA52

7.62x51mm 

750

11 grms

1 grms

2000m

10kg

200:5.20kg 30.4kg

External Gun Pack
Usually, the internal guns were not fitted, but just kept in storage.   For reason of convenience, a gun pod was adopted and used whenever pupil pilots were taken to the gun range.   In effect, with the internal guns installed, these pods could double the amount of guns available.  Like the internal installtion, these gun pods hold 175 rounds, and the pilot may either select all guns to fire simultaneously, or use external and internal guns separately.  Although the pods being offset from the centerline, the pods usually were aimed "straight forward", the combination being essentially used to double the fire time during training.   The setup however could be useful for area straffing.  When the pods are set to aim at a point of convergence ahead of the plane (typically 1000m) selecting either internal or external weapons is less disturbing for the pilot even if the switch requires adapting to the respective effective firing ranges.
 

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