enginehistory.org

[tostrosky]

I am beginning to restore an R-985 I plan to install in a BT-13. The correct starter for the aircraft is an Eclipse H-5 inertial unit. Some of the other radial engine operators I have been talking to reccomend using a direct drive starter so that the engine isn't subjected to the sudden impact that occurs when the inertial starter engages. I like the sound of the inertial as it spools up and I want my plane to be as original as possible. I think that the folks at Pratt & Whitney took the impact of the starter engagement into account during the design of the engine. The impeller spring drive coupling looks like it would absorb the shock before it was transferred to the crankshaft. Is the inertial starter really bad for the engine?

[gwhite]

I'm not sure that I would quantify it as "good" or "bad" for the engien. As you stated, the engine's drive train is designed to take the impact of an interia starter. Having said that, a direct crank starter is porbably gentler on th engine. I admire your enthusiasm for authenticity and if it were me; yes, I'd go for the interia starter. I agree, they sound neat and cranking your own engine appeals to me. I think I would draw the line at a shotgun starter, however..!!!

[jschauer]

I have 100+ hours in a BT-13, it had an inertia starter and we never had any problems with it. Just be darn sure you turn the engine through by hand at least 8 blades before using it. The damage will come from the starter when it hits a hydraulic lock. I now fly as engineer on the CAF's B-29, we have direct cranking starters and use them also to check for hydraulic lock as the starters have a built in clutch to release if you have a hydraulic lock. I know, it works, as I've run into several. Do a good one minute oil scavenge before shutting down and it will reduce your chances of a hydraulic lock.

Round engines forever,
John