Category Archives: Observation

Observation

Helicopter, Trainer, Observation

Avro 671 Rota Mk. I, 529 Sqn RAF (RS Models)

Gallery

TYPE: Autogyro

ACCOMMODATION: Pilot and passenger/observer

POWER PLANT: One Armstrong Siddeley Genet Major IA radial engine, rated at 140 hp

PERFORMANCE: 110 mph

COMMENT: The Avro 671 Rota Mk. I autogyro based on the Cierva C.30 designed by Juan de la Cierva in Spain and built under licence in England by A V Roe & Co Ltd.
Avro obtained the licence in 1934 and subsequently built 78 examples under their model designation, fitted with an Armstrong Siddely Genet Major IA (known in the RAF as the Civet 1) 7-cylinder radial engine producing 140 hp . The first production aircraft was delivered in July 1934.
The first production design in the series was the C.30A, a radial-engined autogyro with a three-blade, 37 ft rotor mounted on an aft-leaning tripod, the control column extending into the rear of the two cockpits. The engine was the five-cylinder, 105 hp Armstrong Siddely Genet Major I. The fabric-covered fuselage carried an unbraced tail plane, without elevators but with turned-up tips. The port side of the tail plane had an inverted aerofoil section to counter roll-axis torque produced by the propeller. As with most autogyros, a high vertical tail was precluded by the sagging resting rotor, so the dorsal fin was long and low, extending well aft of the tail plane like a fixed rudder and augmented by a ventral fin. The wide-track undercarriage had a pair of single, wire-braced legs and a small tail wheel was fitted. This model flew in April 1933. It was followed by four improved machines designated C.30P (P here for pre-production) which differed in having a four-legged pyramid rotor mounting and a reinforced undercarriage with three struts per side. The rotor could be folded rearwards for transport. The C.30P used the more powerful140 hp Armstrong Siddely Genet Major IA radial engine.
Twelve C.30A’s built by Avro for the Royal Air Force (RAF) entered service as the Avro 671 Rota Mk.I. The twelve were delivered between 1934 and 1935. They equipped the School of Army Co-operation at RAF Old Sarum near Salisbury. At least one RAF C.30A was on floats as a “Sea Rota” in January 1935
Many of the surviving civil aircraft were also taken into RAF service between 1939 and 1940. In 1940 they equipped 1448 Flt at RAF Duxford. Later they equipped 529 Sqn at RAF Halton on radar calibration work, disbanded in October 1945, the twelve survivors were sold on to civilian owners (Ref.: 24).

Reconnaissance, Observation

Supermarine “Walrus” Mk.II (Airfix)

Gallery

TYPE: Amphibious biplane reconnaissance and air-sea rescue aircraft

ACCOMMODATION: Crew of three to four

POWER PLANT: One Bristol “Pegasus VI” radial engine, rated at 680 hp

PERFORMANCE: 135 mph at 4,750 ft

COMMENT: The Supermarine “Walrus” (originally known as the Supermarine “Seagull V”) was a British single-engine amphibious biplane reconnaissance aircraft first flown in 1933. It was operated by the Fleet Air Arm (FAA) and also served with the Royal Air Force (RAF). It was the first British squadron-service aircraft to incorporate in one airframe a fully retractable main undercarriage, completely enclosed crew accommodation and all-metal fuselage.
Designed for use as a fleet spotter to be catapult launched from cruisers or battleships, the “Walrus” was later employed in a variety of other roles, most notably as a rescue aircraft for downed aircrew. It continued in service throughout WW II.
The single-step hull was constructed from aluminium alloy, with stainless-steel forgings for the catapult spools and mountings. Metal construction was used because experience had shown that wooden structures deteriorated rapidly under tropical conditions. The wings, which were slightly swept back, had stainless–steel spars and wooden ribs and were covered in fabric. The lower wings were set in the shoulder position with a stabilising float mounted under each one. The horizontal tail surfaces were positioned high on the tail fin and braced on either side by N struts. The wings could be folded on ship for stowage. The single “Pegasus” radial engine was housed at the rear of a nacelle mounted on four struts above the lower wing and braced by four shorter struts to the centre-section of the upper wing. This powered a four-bladed wooden pusher propeller. The pusher configuration had the advantages of keeping the engine and propeller further out of the way of spray when operating on water and reducing the noise level inside the aircraft. Also, the moving propeller was safely away from any crew standing on the front deck, which would be done when picking up a mooring line.
Although the aircraft typically flew with one pilot, there were positions for two. The left-hand position was the main one, with the instrument panel and a fixed seat, while the right-hand seat could be folded away to allow access to the nose gun-position via a crawl-way. Behind the cockpit, there was a small cabin with work stations for the navigator and radio operator.
A total of 740 Walruses were built in three major variants: the “Seagull V”, “Walrus I”, and the “Walrus II”. The Mark IIs were all constructed by Saunders-Roe and the prototype first flew in May 1940. This aircraft had a wooden hull, which was heavier but had the advantage of using less of the precious wartime stockpiles of light metal alloys. Saunders-Roe would go on to build under license 270 metal Mark Is and 191 wooden-hulled Mark IIs.
The successor to the “Walrus” was the Supermarine “Sea Otter” – a similar but more powerful design. “Sea Otters” never completely replaced the “Walruses”, and served alongside them in the air-sea rescue role during the latter part of the war.
The “Walrus” was known as the “Shagbat” or sometimes “Steam-pigeon”; the latter name coming from the steam produced by water striking the hot “Pegasus” engine.
The main task of ship-based aircraft was patrolling for Axis submarines and surface-raiders, and by March 1941, “Walruses” were being deployed with Air to Surface Vessel (ASV) radars to assist in this.
By 1943, catapult-launched aircraft on cruisers and battleships were being phased out; their role at sea was taken over by much-improved radar. Also, a hangar and catapult occupied a considerable amount of valuable space on a warship. However, “Walruses” continued to fly from Royal Navy carriers for air-sea rescue and general communications tasks. Their low landing speed meant they could make a carrier landing despite having no flaps or tailhook (Ref.: 24).