CAB (Caproni Bergamo) AP.1, little-known version of the Ca.307

Hi friends,
On 'Ali antiche' (Ancient wings) # 91, house organ of GAVS (Gruppo Amivi Velivoli Storici, member of European Aviation Preservation Council and British Aviation Preservation Council) there is an interesting features with a picture (and some enhancement of others) depicting an unknow version of the CAB (Caproni Bergamo) Ca.307, better known as the AP.1.
AP.1 was a not very successful ground attack aircraft, in the same class of Breda 64 and the Curtiss-Wright A-12 Shrike. For Regia Aeronautica, except some ex-Paraguayan repossessed aircraft, was built in two batches: Serie I (12 aircraft, serialled 75000 to 75011 inclusive) and Serie II (27 aircraft, MM.75012-75038). Both series have a semienclosed cockpit for the pilot and a rear one for a gunner, with a machine gun.
The photographs we speak of, owned by Alessandro Meneghini and published by Paolo Stanchina, depict an aircraft with tandem seat enclosed by a long canopy and a different design of the upper rear fuselage. Only one aircraft of that version appears in the photographs, coded 76-10, meaning that the aircraft was in service with 76a Squadriglia (76th Flight) of 7° Gruppo (7th Squadron) from 5° Stormo Assalto (5th Assault Wing), part of 5a Brigata Aerea d'Assalto (5th Assault Air Brigade), headquartered at Rome-Campino Sud.
The late Rosario Abate, in his 'Gli aeroplani della Caproni Aeronautica Bergamasca' (a 1975 "bible" on the matter) about the series production of the AP.1 for Regia Aeronautica wrote: "...In June (1936) (...) Regia Aeronautica received two experimental AP.1". The Author intends that the two "experimental aircraft" are part of the 27-plane Serie II. Perhaps are two prototypes of this trainer version?
Later on Rosario Abate quotes a variant of the serie production AP.1 with an Alfa Romeo AR.127 engine (apparently standard on all Serie II or most of them), designed on April 1937, with a different position of the gunner, under an elongated canopy, and a ventral machine-gun; a further variant (March 1938) had dual controls. Perhaps those two designs were the basis of the two-seater trainer?
In fact is not an usual occurrence to find a totally unknown version of an aircraft fielded and operational, at least for a short a time.
If someone could enlighten us on that matter, I think all the fans of Regia Aeronautica could be delighted

Nico

Nico said:

... Perhaps those two designs were the basis of the two-seater trainer?...

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That seems very probable Nico. Similar developments were seen with the contemporary Breda Ba.64.

Found this 3-view of the CAB AP.1 with the Alfa Romeo on a drive along with a CP.3 schematic posted earlier.
AP.1 with Alfa Romeo 126 RC35 9-cylinder engine. Wingspan: 13.01m Length: 9.12 m Height: 2.95 m Wing Area: 27.01 sq m
I think it may have come originally in GLI Aeroplani Della Caproni Aeronautica Bergamasca Volume Primo (Edizioni Bizzarri Roma 1975) by Rosario Abate as the images seem almost identical.

Here is a two studied Projects;

http://www.alieuomini.it/AJAX/catalogo/dettaglio2_catalogo/4/

STUDIES AND PROJECTS

Some studies on modifications or new versions of the basic project of the P.1 merit being mentioned.

For the adaptation of the aircraft to the use of snowy fields there are three separate studies concerning the application of skis or snow shoes.

The study of the adoption of French engines of greater power was also set on the standard A.P.1. Therefore, a study of August 1936 provided for the use of the 8,000 c.v. air-cooled 14-star 14-cylinder Gnome & Rhóne K 14. at 3200 m.; as a two-seater this version would have been equipped with 3 arms and 200 kg. of bombs, and as a single-seater of 2 weapons and 438 kg. of bombs, but without radio installations and photos.

A subsequent study of March 1937 instead considered the adoption of a Hispano Suiza 12 Y 12-cylinder straight-V engine cooled by 910 c.v. at 3600 m. operating a 3.20 m triple helix. in diameter, with the following dimensions: wingspan 13 m, length 9.85 m, height 3.85 m.

Of the standard A.P.1 with Alfa 126 was studied in April 1937 a modified variant involving a more backward arrangement for the observer under a prolonged glazed cabin and the adoption of a weapon in depression for the inferior-rear defense.

Another study of March 1938 involved the adoption of double commands for the second member of the crew, also serving as a dorsal weapon operator. The launch armament consisted of two cal machine guns. 7.7 or 12.7 mm. wings with 500 c.p.a., a dorsal weapon cal. 7.7 mm. with 500 shots and a similar ventral weapon with the same ammunition for depression shooting. The bombiero compartment could house 4 100 kg bombs. or 7 of 50 kg. or a variable number of other smaller-sized bombs.

Finally, a further study of an unspecified period. but it could be placed within the embracing period the dates already quoted, incorporating the following modifications: a prolonged and profiled full-length glass cabin, a backbone completely enclosed by the glazing, squared fletching and a lying observer on the floor of the fuselage for aiming, which makes to think that it was a version destined no longer to the assault but, like the two other versions mentioned above, to the survey and the small bombardment at altitude.

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Hi,