Propeller spinner & metal spinning

Suomeksi

A black block appeared to the restoration room of the Tuesday Club of the Aviation Museum Society at the Finnish Aviation Museum during last winter. The black block is a propeller spinner of the VL Myrsky.

Black spinner of VL Myrsky is suprising big. Photo: Reino Myllymäki

The spinner has been in a display cabinet in the heritage room at Kauhava airbase. According to the text on the spinner, it has been donated by lieutnant colonel Antti Uotila in 1998. After the sale of the airfield, the spinner has been stored at Kauhava. Finally a delegation delivered it to Vantaa from Kauhava.

The spinner had three work in VL Myrsky. Firstly it protected constant speed propeller hub agaist water, ice and dirt. Secondly it decreased drag. Thirdly it expanded the cooling of the radial engine. The spinner of VL Myrsky has three small blades to boost cooling. They were needed since the Twin Waso engine ran warmer in the VL Myrsky than in the Curtiss Hawk.

A hub of VLS 8002 propeller. It is a copy of Hamilton Standard Hydromatic. The semifinished hubs were acquired from Sweden. Photo: via Kalevi Keskinen.

These small cooling blades have been invented at the State Aircraft Factory along the test program of the MY-4 in 1943. The inventor has been rewarded.

Luckily the spinner of the VL Myrsky has been preserved and donated to the VL Myrsky II restoration project. Otherwise it should be made by the metallic spinning.  The project has enough lacking axially symmetric metallic parts. Antero Flander is manufacturing the pot plate at Rautalampi and the NACA ring will be probably more demanding part.

The spinner inside. The imprint of work is more rough inside. Photo: Reino Myllymäki

The metallic spinning is a work method where a disc or tube of metal is rotated at high speed and formed into an axially symmetric part. The forming tool has been made from wood. Later the tool has spinnig tip, too. In addition to metallic spinning some other methods like English wheel are needed in the manufacturing of more complex parts.