First recording is of 2 Executives taking off.

Spectrogram of Spartan Executive take off

Second recording of 2 aircraft in a display. The two aircraft are discernible by the note of the engine/propeller, obviously a radial.

Spectrogram of 2 Spartan Executive in display

One of the aircraft is based (as far as I know) at Little Gransden. In the display is the leading aircraft.

The PT-22 Recruit was the first trainer aircraft to be used by the United States Army Air Corps with a single wing (monoplane). Powered by a single Kinner R-5 Raidial. The aircraft has a peculiar sound due to a odd arangement of exhausts and cylinders (a high speed waltz?).

Heres a photo I took of one of the displaying aircraft during the display on the day.

Ryan PT-22 Recruit, Old Warden, 2nd August 2009

Recorded on 2nd August 2009, Old Warden, Beds, UK.

Harvards have a very particular sound as like a Stearman there is no gearing between the engine and propeller which consequently moves very fast, with the propeller tips breaking the speed of sound as they turn.

One of the North American Harvards taxying after the display, Old Warden, July 2009

The aircraft is a true combat veteran and is operated by Kennet Aviation based at North Weald.

Powered by a single Siemens Sh 14 A-4 7-cylinder radial engine producing 118 kW at 2,100 rpm (160 hp).

Recording made on 3rd May 2009.

FW44J G-STIG at Old Warden 2008

The Fw 44 was designed as a biplane with conventional layout and straight, non-tapered wings. Its two open cockpits were arranged in tandem, and both cockpits were equipped with flight controls and instruments. The Fw 44 had fixed tailwheel landing gear. It employed ailerons on both upper and lower wings. It did not use flaps. It was flown with a radial engine.
The first prototype flew in 1932. After many tests and modifications to increase the plane’s durability and aerodynamics, the final Fw 44 proved to have excellent airworthiness.
A second version of the Fw 44 was the Fw 44B, which had an Argus As 8 four-cylinder inverted inline air-cooled engine of 90 kW (120 hp). The cowling for this engine gave the plane a more slender, aerodynamic nose.
20 Fw 44s purchased by China were modified for combat missions and participated in the early stage of the Second Sino-Japanese War until all were lost in action.
The last series version was Fw 44J, which was sold or built on license in several countries around the world. It ws equipped with a seven-cylinder Siemens-Halske Sh 14 radial engine.

http://en.wikipedia.org/wiki/Focke-Wulf_Fw_44

Recorded on 3rd May 2009.

powered by a single Bristol Mercury IX radial engine

From Wikipedia – “The Gloster Gladiator (or Gloster SS.37) was a British-built biplane fighter, used by the Royal Air Force (RAF) and the Royal Navy (as the Sea Gladiator variant) and was exported to a number of other air forces during the late 1930s. It was the RAF’s last biplane fighter aircraft and was rendered obsolete by newer monoplane designs even as it was being introduced. Though often pitted against more formidable foes during the early days of the Second World War, it acquitted itself reasonably well in combat.
It saw action in almost all theatres during the Second World War, with a large number of air forces, some of them on the Axis side. The RAF used it in France, Norway, Greece, the defence of Malta, and the brief Anglo-Iraqi War (in which, ironically, the Royal Iraqi Air Force was similarly equipped). Other countries deploying the Gladiator included China against Japan, beginning in 1938; Finland (along with Swedish volunteers) against the Soviet Union in the Winter War and the Continuation War; and Norway, Belgium, and Greece resisting Axis invasion of their respective lands.” – http://en.wikipedia.org/wiki/Gloster_Gladiator

Powered by two Pratt & Whitney R-1830-92 Twin Wasp radial engines, developing 1200 hp (895 kW each) each.

A windy day and overcast day at Old Warden. My usual micing arrangement was supplemented using some natural windbreaking.

The audio and photo are of the same aircraft.

Catalina PBY5A

From Wikipedia – “The Consolidated PBY Catalina was an American flying boat of the 1930s and 1940s produced by Consolidated Aircraft. It could be equipped with depth charges, bombs, torpedoes, and .50 Browning machineguns and was one of the most widely used multi-role aircraft of World War II. PBYs served with every branch of the US military and in the air forces and navies of many other nations. In the United States Army Air Forces and later in the USAF their designation was the OA-10, while Canadian-built PBYs were known as Cansos.
In World War II, PBYs were used in anti-submarine warfare, patrol bombing, convoy escorts, search-and-rescue missions, and cargo transport. The PBY was the most successful aircraft of its kind; no other flying boat was produced in greater numbers. The last active military PBYs were not retired from service until the 1980s. Even today, over seventy years after its first flight, the aircraft continues to fly as an airtanker in aerial firefighting operations all over the world.
In the initialism PBY, “PB” stands for “Patrol Bomber” and “Y” is the code for “Consolidated Aircraft”, as designated in the U.S. Navy aircraft designation system of 1922.” – http://en.wikipedia.org/wiki/PBY_Catalina

The recording and the image are of the same aircraft. This aircraft is powered by a single 840 hp (627 kW) Bristol Mercury IX air-cooled radial piston engine.

Gladiator in pre-Second World War RNoAF colours

Powered by a Pratt & Whitney R-1830 “Twin Wasp” radial engine.

A Grumman Martlet/Wildcat at the Imperial War Museum, Duxford, photographed by Robin Stevens on 26 May 2007.

The audio and the aircraft in the image are of the same aircraft but not taken at the same airshow.

FG-1D Corsair at the 2008 'Flying Legends' air show in Duxford, UK.