Ford/Mazda Duratec 23/25 Semi Direct Drive, is this feasible?

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Jonathan_Schmidt

New Member
Joined
Mar 21, 2013
Messages
1
Location
Norco, CA USA
Greetings,

I've been reading your responses and posts and find this site wonderfully useful for dreaming. I have, sadly, a dream that keeps sticking around. I'm working on a Bucker Jungmann replica. I've got plans from multiple vendors, and have been performing CAD, structural analysis and modeling of the aircraft. It seems buildable. I need a reliable engine of about 90HP. When I look at the power curves of the Duratec 23 in my Ford Ranger, it seems to line up, if I accept the weight penalties. So here's the topic for discussion. If I use a prop designed for a Jabiru that spins as fast as 3300 RPM, and I use the engine directly, and derate it down to 100 HP, I'm well within the Power/RPM curves. If I attack the propellar to the draveshaft, but support the shaft with a axial load bearing, I don't think I'm applying too much beyond what the engine is designed to do. The engine is heavyish, but still within the weight the aircraft can weight and balance for. I'll admit I'm attracted to the engine's cost. $3,500 NIB isn't too bad. I'm also attracted to the cowling, the plane will look like an HE51 when complete. I also look forward to the testing, I'm an operational test and evaluation engineer, afterall. I've anticipated the machining that needs to be done, and I'm fairly good on my old Vert Mill. So what did I miss, it can't be that easy.
 

wizzardworks

Well-Known Member
Joined
Nov 8, 2011
Messages
273
Location
murfreesboro NC USA
Jonathan, Along with axial loads there are large gyroscopic loads and thrust loads to account for. These three loads must be supported external to the engine and on a shaft with a diameter that is likely larger than the rear crankshaft bearing diameter of a 2.3 liter engine.
wizzardworks
 

PTAirco

Well-Known Member
Joined
Sep 20, 2003
Messages
3,522
Location
Corona CA
If you look at this thread https://www.homebuiltairplanes.com/forums/firewall-forward-props-fuel-system/15278-quill-shaft-design.htmlhttps://www.homebuiltairplanes.com/forums/ford/15071-ford-mazda-duratec-23-25-semi-direct-drive-feasible.html#post172494 you'll see some of the problems that are likely occur with a direct drive conversion.

Do you happen to know what kind of crank material is used in that engine? Probably not forged? At the very least you'd want some kind of bearing at the output end of the engine to take prop loads.
 
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