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Title: Yak 1 propeller control: Variable pitch or constant speed. Post by: Graham Boak on March 12, 2016, 03:45:13 PM This thread http://forum.keypublishing.com/showthread.php?138174-Yak-1-propeller-control-system has discussed the question of how propeller pitch was controlled on the Yak 1. By implication, also on other Soviet fighters of this period. It is suggested that the aircraft had a constant speed propeller, as might have been expected from the period, but also that the pilot would control the propeller pitch. The two are apparently contradictory. However, in a recent post someone has described just such a system on the Percival Proctor, postwar.
Could someone describe how the Soviet designers treated the matter - which were the first Soviet types with variable pitch propellers, and when were constant speed units introduced? The Yak 1 will then be covered, if only by implication. Title: Re: Yak 1 propeller control: Variable pitch or constant speed. Post by: Dark Green Man on March 13, 2016, 01:45:56 AM I know that VISH translates into English as something that means the same as variable pitch propeller.
Vish-61P with M-105P Vish-105 with M-105PA Vish-107LO with VK-107A Title: Re: Yak 1 propeller control: Variable pitch or constant speed. Post by: KL on March 13, 2016, 03:53:12 AM which were the first Soviet types with variable pitch propellers, and when were constant speed units introduced? First variable pitch propellers on series Soviet types were Hamilton Standard propellers made under licence. It looks that licences for several variable pitch Hamilton Standard designs were bought around 1937. All I-16 fighters, SB bombers, DB-3 bombers and PS-84 transports (licence made DC-3) made after 1937 had engines designed in US or France and variable pitch propellers designed by Hamilton Standard. Constant speed governor (in Russian RPO for Regulator Postoyannih Oborotov) was also a Hamilton Standard design. Governors made under licence were known in USSR as R-2. Redesigned governor R-7 was used with VISh-61 propellers installed on early Yak-1. This is how propeller controls are described in Pe-2 manual: Quote Винтомоторная группа самолета снабжена металлическими трехлопастными винтами с изменяемым в полете шагом (АВ-5ЛВ-139, ВИШ-105П или ВИШ-61). Эти винты при помощи, регулятора постоянных оборотов Р-7 могут менять свой шаг автоматически и принудительно. Летчик может устанавливать различное число оборотов винтов путем затяжки пружины регулятора при помощи штурвала управления, благодаря чему угол установки лопастей винта уменьшается или увеличивается Power plant is equipped with a metal three-blade in-flight variable pitch propeller (AV-5LV-139, VISh-105P or VISh-61). These propellers using the "constant revolutions regulator" (i.e. constant speed governor) R-7 can change their pitch automatically or by pilot's command. The pilot can set a different number of revolutions of the propeller by tightening the regulator spring with the control wheel, so that the installation angle of the propeller blade decreases or increases HTH, KL Title: Re: Yak 1 propeller control: Variable pitch or constant speed. Post by: Graham Boak on March 13, 2016, 10:08:24 AM Thank you. Much the same process happened in the UK, with De Havilland buying a licence from Hamilton Standard variable pitch propellers followed by the company Rotol being set up for constant speed units/propellers. DH then followed with a CS version.
I don't understand why the pilot would want to override the automatic. Changing the propeller rpm will change the engine rpm, because the two are linked with a fixed gearing. I rather thought that was what the throttle was for. I shall copy your response, with credit to you and this board, across to the original inquiry. Title: Re: Yak 1 propeller control: Variable pitch or constant speed. Post by: KL on March 13, 2016, 10:50:29 AM This is a section through Soviet RPO R-7
(http://aviaciaportal.ru/engine/uploads/prjamaja-shema_3.jpg) No 1 are L-shaped centrifugal weights, No 2 is spring mentioned in previous post, No 8 pulley for command cable from cockpit Following schematic demonstrates how constant speed governor works: (http://aviaciaportal.ru/engine/uploads/prjamaja-shema_4.jpg) How governor is connected with the control wheel in the cockpit (http://aviaciaportal.ru/engine/uploads/prjamaja-shema_5.jpg) HTH, KL |