RCU Forums - View Single Post - Importance of engine break-in ?

05-09-2009 | 07:11 AM

#40

DarZeelon

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From: Rosh-HaAyin, ISRAEL

RE: Importance of engine break-in ?

Quote:

ORIGINAL: Trisquire

I had a thought in reference to bench running. How is a tied down airplane any different from a bench run? I mean, tie your plane securely to a bench, up out the dirt. Okay, you're exposing your radio equipment to so some unneeded vibration.

The thing is, the carburetor/tank relationship effects tuning. If you run an engine on a bench, you've already established one engine/tank relationship, and you've tuned accordingly. When you transfer the engine to the plane, you can try your best to get the tank on the same level. Invariably, the setup will differ in some subtle way, and you'll have to retune all over again. You're duplicating your efforts. Why not establish the correct carburetor/tank relationship once, in the plane, and then leave the mixture alone forever? It's one less variable to contend with.

Tom,

Starting a new engine can be a particularly nasty experience...

If you install your new engine in your new model for break-in, you would necessarily expose this model, to the same 'quirks and idiosyncrasies' that the engine exposes you...

Also, an engine; ANY engine, must be mounted so the setup places the tank as close as possible to the engine (unless you have a pump/regulator) and with the carburettor's jet and the same level as the tank's center-line (with the model in level-flight attitude). A test-stand setup should be very close.

The reason your engine has carburettor needles, which you can turn at will, is because you are expected to do so... Whether it is done to compensate for changing ambient conditions, or for a different setup, or to achieve the engine's primary running setup...

If you realistically expect your setup to remain completely the same, from the end of break-in, to kingdom come; just because you broke the engine in on the plane... well, you're probably not in the right kingdom...

Face it.
1. A break-in is much safer and easier to do on the ground and at your immediate control than it is in flight; obviously not at your immediate control.
2. A break-in is much safer and easier to do, with the engine mounted in a test stand than with the engine mounted on your new plane.

While I strongly respect Clarence Lee and his elaborate procedure; I believe real modelers, who do make mistakes, should stick to the ground procedure, for the initial break-in (three tanks/30 minutes in a ringed engine)...

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