Frog 160 Red Glow (1948)

The FROG 160 Red Glow was the first purpose made glow-plug engine produced by International Model Aircraft Ltd (IMA) in mid 1948 under their FROG brand name it was in fact the first small capacity glow-plug engine to be series produced in the UK it remained in production until the Autumn of 1950. It should be noted that the E.D. 2.49 cc Mk. III which had been released about five months earlier had been supplied with a glow plug conversion kit as standard but was supplied assembled by FROG in its diesel configuration.

From a production perspective the FROG 160 Red Glow engine design was effectively just a minor variation of FROGs existing bicycle spoke engine design which was verging on obsolescence even when the FROG 160 Red Glow was first produced no doubt this was reflected in its relatively limited production lifetime. Engine serial numbers were preceded with the letters RG standing for Red Glow the example pictured here bares the serial number RG 1.952 and was likely produced in 1949. The FROG 160 Red Glow was supplied with a KLG mini-glow plug as standard as depicted in this picture.

In the late 1940s no commercial UK glow fuels contained nitromethane which explains the relatively low power output which was recorded as 0.083 BHP at the time later fuels such as Nitrex 15 containing 15% nitromethane proved to raise the engines output to a more reasonable 0.1 BHP which in practice resulted in about 350 RPM increase on a given suitable propeller.

Capacity 1.665 cc (1.016 cu in) - Bore 12.32 mm (0.485 in) - Stroke 13.97 (0.55 in) - Power (no nitromethane) 0.083 BHP 10750 RPM (0.062 KW) - Ignition Glow-plug - Induction Front rotary valve - Piston Liner Cast iron piston Steel liner - Recommended propeller 8x5 - Weight 62.15 g (3.25 oz)