For Morgans ...Rotax (x 2)

" Mmmmmmm....no. An engine failure in a single-engined airplane requires a
deadstick landing. Bad, yes, depending on where it happens, but the pilot
uses
the same skills he or she uses on every flight."

Mmmmm...no the problem is most GA pilots use powered approaches,
particularly flying into controlled airfields during a normal flight. A
"deadstick" presents them with an opportunity for poor decision making.


An engine failure on a
twin-engine plane puts the pilot in an unusual mode of flight. Yes, a
pilot
with current skills and the right training will have a better chance to
bring
the aircraft home intact. But in the real world, it doesn't work out that
way.
*Any* emergency is bad. Pilots die after engine failures in twins, too.

Yes, usually associated with asymetric control issues. I'm guessing more get
home after a single engine failure than don't.


The Tucano should avoid some of the problems due to centerline thrust, but
the
fact is, it has twice the fuel burn, twice the propellers, twice the
ignition
sources, and twice the exhaust heat of a single-engined airplane. There
are
more things to break, more chances to lose power unexpectedly, more
chances to
mismanage fuel, and more things that can start fires.

Fair comment, except that the single engine performance in cruise suggests
that may be a "normal" mode of operation. I think the potential for this
aircraft is in operations over water, hostile terrain. Maritime or forestry
patrol etc.


Two stroke engines are about twice as apt to quit than "conventional"
aircraft
engines. The solution is not to use *two* of them, but a single
more-reliable
powerplant.

Before I converted to ultralights from GA, I was pretty concerned that one
day the fire would go out and bad things would happen. I never had an engine
failure in GA, and I haven't had one in an ultralight yet either, but I'm
not concerned about it, when you do most of your flying at 500' or less, you
are always noting the location of the best forced landing area, taking the
long way around "tiger" country etc. The problem with conventional 4 stroke
aircraft engines has been weight, and the need to put them into a bigger
heavier airframe. I'm very encouraged by the developement of engines like
the HKS and Warner, as they appear to offer a nice blend of light
weight/power/reliability.



As for those wonder how eager the market is for twin-two-stroke
centerline-thrust airplanes, I just have three words: Powers. Bashforth.
Minimaster.

Don't know anything about those, my only comment would be that the problem
may have been a business, marketing etc issue and not the concept in
general.

Ian

.. The problem with conventional 4 stroke
aircraft engines has been weight, and the need to put them into a bigger
heavier airframe. I'm very encouraged by the developement of engines like
the HKS and Warner, as they appear to offer a nice blend of light
weight/power/reliability.



Ian


Published performance specs for the HKS:
56HP @5800RPM 4.2gph/.45bsfc.
This will require a volumetric efficiency of 110%. Not bad for an
engine running at 75% throttle. In fact, not very likely.

Published performance specs for the Verner:
63HP(75%) @3750RPM. 2.7gph/.25bsfc Much more reasonable 55% volumetric
efficiency with 75% power, but absolutely astonishing fuel efficiency.
In fact, not very likely fuel efficiency.

Both engines achieve their light weight by running at high rpm with
small displacement, and by using Nikasil aluminum cylinders. Which is
to say, they are race car engines.

Would you rather have a C-85 with 2000 hours TT or a Verner with 600
hours TT? Or a 2 stroke with cast iron cylinders?

I would appreciate it if someone would check my numbers and see if they
come up with similar results.

--
John Kimmel

remove x

"He's dead, Jim."