D-Motor

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MikeGodsell
Posts: 87
Joined: Wed Jan 02, 2008 11:32 pm
Location: West Wales

D-Motor

Post by MikeGodsell » Wed Sep 03, 2014 9:22 am

New engines seem to be my particular interest, so thanks again to the two Brians for info on the D-Motor in Sept's mag.
Anyone running a pre 1970s car will know the vapour lock and boiling carb problems of using modern unleaded mogas with 5% (soon to be 10%!) ethanol. The D-Motor appears to be designed to use such fuels, and does away with carb heat as well. So why do I have mixed feelings about this splendid new motor?
Perhaps it's an age thing, but I have always flown behind a motor that will keep running so long as it has fuel. Loss of electrics in an aircraft with magneto ignition and pressure instruments is a non event.
However a failed generator drive belt in a modern glass cockpit D-Motored aircraft (with high pressure electric fuel pump & ECU plus Electronic ignition) will quickly result in loss of the engine and next to no instruments ... an interesting forced landing situation!
For sure modern car alternators and engine ECUs are very reliable, and proper maintenance makes a drive belt failure and associated battery failure unlikely. So what's my problem?
Well we can't keep reinventing / improving the wheel indefinitely ... sooner or later progress to something better must come ... if only to avoid boredom. Surely that better thing is diesel power, and in particular the Weslake Aero Diesel. Exceptional economy, full power at altitude, no valves, no spark plugs, no carb heat, good power/weight, etc.
But for me the bottom line is ....If you have ever seen the sad remains of a light aircraft that has crashed and burnt you will know where I am coming from. Diesel is inherently safer than petrol ... try standing in a pool of diesel and then a pool of petrol while throwing lighted matches!
I look forward to the next progress report on the Weslake diesel :)

Steve Brown
Posts: 257
Joined: Wed Jan 02, 2008 11:00 am

Re: D-Motor

Post by Steve Brown » Thu Sep 04, 2014 1:36 am

Agree with a lot of your points though one electronic ign and one magneto gives the best of both worlds and many modern diesels (ie like the Weslake) seem to use HP common rail injection with an ECU and electric solenoids on the injectors so they are not always so immune from risk of electrical failure as one may think.
I agree about the reduced fire risk - and similarly avgas is less volatile than mogas.

Regards
Steve

Brian Hope
Posts: 1271
Joined: Tue Jan 08, 2008 8:28 pm
Location: Sheerness Kent

Re: D-Motor

Post by Brian Hope » Thu Sep 04, 2014 6:46 am

... try standing in a pool of diesel and then a pool of petrol while throwing lighted matches!

Please don't! :shock:

I agree diesel is 'safer' in some respects, although the powers that be seem to have done a bit of a U turn and those of us that drive diesel cars are now 'unclean' in terms of emissions, well for this week anyway.
Steve's point about modern diesels having the same potential failure modes in terms of electrics certainly applies to the Weslake, which has electronic fuel injection. It will likely need a back up battery that is protected from the 'normal' electrical system for emergency switch over, as petrol electronically controlled engines have. The one mag, one electronic systems are only good for 'conventional' engines that are being upgraded, most modern engines are being designed with twin electronic systems. The Weslake incidentally,has provision for twin injectors, but how far do you go with redundancy though? I was going to say you live with the fact that there's only one crankshaft but in the Weslake there are two!
I am definitely a Weslake fan though and really hope it comes good. It's British, it targets the obvious market, it is the right shape and size, it's a work of art to look at, and they are a great bunch of guys down at the factory. I'm also of an age where I remember Weslake's speedway success and it was great to see Peter Collins' world championship winning bike at Sywell.
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