snips...

al p wick wrote:
> Your reputation precedes you. I'd be happy to provide more info if there
> was a reasonable exchange of rhetoric. Under what circumstances would YOU
> describe a rotary engine as risky install? Can you think of any scenario
> that would lead you to that conclusion? I'm trying to understand the
> depth of your conviction.
>
> -al

If you won't debate the issues attack your opponent :)

Paul Lamar


Al,
You introduce a valid topic. FMEA is such an effective tool it is
mandatory in the certification of Part 25 and part 23 aircraft (or that
change to part 23 still in an NPR?).

To be fair to this group though, FMEA is not a replacement for good
basic engineering. FMEA is just another tool in the tool box, a
regimented approach to help ensure you didn't miss any areas which need
that good engineering. FMEA will help you identify the areas of concern
(Fatal accidents is the more traditional way to highlight these- you can
see why FMEA is becoming popular). Although no one has done such a
thorough detailed FMEA, we believe we have hit on every area and
component, and I have been trying to assemble the best practices
www.wankel.org <http://www.wankel.org> (welcome any help on this).

Your introduction was  "One thing is abundantly clear, it (the rotary
installation is a very high
> risk install. Substantially higher than the Lycoming"

Higher risk than a newly manufactured Lycoming in a Part 23 aircraft? Or
higher risk than self overhauled Lycoming with an aftermarket EFI,
Ignition system , one old used magneto, in a homebuilt aircraft?

A brand new lycoming in an RV exactly to VANS plans is by far the lowest
risk approach (actually a B777 is the lowest risk approach).Most people
on this list not going to choose that route even if they can afford it.
Paul will be the first to say that water cool aero engines make as much
sense as air cool submarines, but the fact is, all the potential well
engineered automotive core engines we have to choose from are water cooled.

You specialise in FMEA and yet you chose the subaru.

Single plug per cylinder against the rotaries two (On your site you
state loose a plug and you loose 25 percent power. I bet you loose less
than 50% thrust as your prop is no longer matched to your torque curve,
so you aren't going to get to the peak RPM where you would maybe get 75%
power from the other cylinders).

Alloy piston in alloy block. Overheat it, and you could seize. Overheat
the iron rotor, and the alloy housing grows faster and increases
clearance, so you just loose power. Although long before the power lose
is evident your have shrunk your housings and started loosing water.
Nice soft failure mode.

We won't even get started on exhaust valves.

Otherwise, beyond the core engine, the challenge is very similar. The
ancillaries will kill you just the same. Fuel system, cooling system,
oil system, igition system. To be fair to the Sube, the lower EGT and
oil pressure are there an advantage.

Rather than come in with guns blazing, why not come in with a
constructive approach to how we can do a useful FMEA?

Regards,
Mark