RCU Forums - View Single Post - Vintage Forster .29 fuel and glow plug type
Old 02-27-2023, 02:49 PM
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LLRCFlyer
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Default Forster .29 plug

MEOWY84,

Idle bar glow plugs were designed for use in loop-scavenged engines to keep raw incoming fuel from spraying on the glow plug's coil and quenching it during extended low power/low heat (idle) operation. Control line and free-flight engines without a throttle do not idle and therefore do not need idle bar glow plugs. So, unless your vintage Forster .29 (early 1950's) has been modified to add a throttle, then use a non-idle bar plug and determine the proper heat range by trial and error.

Unlike loop-scavenged engines, Schnuerle scavenged engines don't spray as much fuel on the glow plug and hence do not need an idle bar, but the .29 Forster was long out of production before Schnuerle porting was invented.

If you want more information on the Forster .29, go to Scepter Flight Model Engine Tests (Sceptre Flight). There is an engine review article on the Forster F-.29 taken from the August 1952 edition of Air Trails Magazine.

David