info wanted please

[soyuz]

in the older planes like the dc3 and trimotor their are engine "primer" controls wat do they do, what were they used for this may be a dumb question but i would like to know so i can use proper start up sequences in these older planes thanks for any help

[wheeler_1028]

A primer in an aero engine is similar to a choke in a car. It is used for staring when the engine is cold. The primer is used to inject fuel directly into the induction manifold to promote an easier engine start. It operates similar to a syringe - sucking in fuel and then injecting it into the induction manifold. It is then locked in the closed position and not used for the remainder of the flight. Improper use can flood the engine. They are mainly found on carburettor engines, whereas fuel injected engines generally use a fuel pump for engine priming.

Not sure of it's application is MSFS though, and whether or not operating the primer makes any difference to engine starts.

Hope that helps.

Wheeler_1028.

[lnuss]

About all I can add to this is that the primer is used on a cold engine, when you're talking about the typical light aircraft with a horizontally opposed engine (use with a warm engine floods it), but many (most?) radials need primer for every start -- that was certainly true for the 300 hp Jacobs we had in the Stearman I used to fly.