Hi Greg,

I've always wondered the same. To take his question and run with it, why
are small turbo props not the defacto engine used throughout small GA
planes?

As said before by Peter Duniho, they simply don't suit well. There scaling
down is making them inefficient, there fuel consumption - especially at
lower altitutes - is higher, so is the amount of fuel to be loaded for the
same distance.

If you take a look at the turboprop conversions 'done' to the P210, the
Bonanza and so on, you'll find that there range is reduced. Some
conversions cope with this by improving the load (more hp, proved to fly
with a few extra pounds). But all in all that makes these planes not more
efficient - especially the ones normally operated at lower altitudes - the
ones without pressurization.

Seems to me that a variety of small jets and turbo props could be made,
which are just as safe and have slightly better performance envelopes than
currently exist while having less failures and vibration to boot.

There _will_ be a lot of new small jets - but none of them in a 'normal'
price range of a spam can. The engines are much to costly for that. Lowest
priced jet - if completed - will be the D-Jet by Diamond Aircraft. Single
engine jet with a maximum FL of 250 (and I just can't see how they will
cope with making this engine efficient at that altitude...)

Is simple economics the answer? $30k piston versus something like $80k
turbine, or something like that?

Much more. Especially maintenance is cruel. Turbines do have less moving
parts, but the parts are of a much higher quality and the personnel is
trained as hell...

regards,
Peter