A 2-stroke is a 2-stroke is a 2-stroke.

I own one outright, have a share in another, have looked closely at many
others and quizzed many other owners. If you're a fellow-member of the
self-launch owners club they'll talk honestly because they think you
won't rat on them - one day you'll have to sell one too. All of the
engines, as engines, are about equally reliable. The problem with all
of them is that a 2-stroke continually tries to vibrate everything
attached to it to death. Fuel line joiners, electrical wiring,
thermocouples, temperature transmitters, starters, flywheels,
alternators, magnetos, ignition boxes, fuel pumps, carburettors, drive
trains, radiator mountings, cooling hoses, EVERYTHING - including the
aircraft.

The reliability of the engine itself is not the problem. What brings
the system undone is the vibration induced failure of essential
accessories and other components. Straight, simple engine failures do
occur but a vibration induced failure somewhere else in the chain is
much more likely to leave you in trouble - and it will do so quite
often. Won't extend, won't start, won't retract, broken drive belt, are
all just as much engine failures as a broken crankshaft and much more
common.

I'm afraid that's the dirty, little secret all of us self-launcher
owners keep to ourselves.

Of course except for Schleicher's Wankel. Mind you, when the Wankel
does go you need to have a lot of money saved up. Your local A&P will
be even more reluctant touch it than he is with a 2-stroke so you'll
have to put it in a box and post it to Poppenhausen. That's why Rotax
and Solo still find a home.

Safety - They're all safe if you keep your hand and head out of the prop.

Maintenance - never take your eyes off the wiring, the fuel lines, the
brackets, the flanges, the hose clips, the staked bolts, etc.
Accessible - none of them are accessible within the normal range of
human limb mobility. DON'T buy one that needs to have its fuel lines
changed regularly!

Don't get me started on the engineering quality that demands stainless
braided, aircraft quality fuel lines - joined by NYLON barbed fittings!

And for a normal single-seater, anything less than about 45-50HP is a
sustainer, not a self-launcher, no matter what it says on the box.

GC

On 11/01/2012 11:48, key wrote:
I am curious what group members with experience with self-launchers
regard as the best propulsion system (currently) in terms of in-flight
restart reliability, maintenance, safety, and other operational
factors (e.g., vibration). Of course the electric Antares might win
on all counts except for range, but it is out of my price league.

thanks,

Key