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<< Lancair Builders' Mail List >>
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See, I knew I'd piss off a Continental owner. My bad luck it is one as
informed and experienced as Charlie.
<<The TSIO 550 has a bore of 5.25 inches and a stroke of 4.25inches.
It develops 350 horsepower at 2700 rpm. Therefore, we can assume the 25
horsepower is derived from the extra stroke. Not rpm, as Brent mentioned.>
Busted! The 550 is a stroked out 520. Stroking an engine increases ring
speed and piston acceleration leading to accelerated ring/cylinder wear. As
I recall, and I may be wrong, I have a history of that, the 550 was designed
for the Piper Malibu. Piper was soooo impressed with the 550s smoothness and
reliability that they couldn't stand it and decided to re-engineer the
airframe for the Lycoming TIO-540-AE2A and offer the airplane as the Malibu
Mirage. Again, I could be wrong on this but as I recall, the 550 had been
certified at 310 Hp at 2,600 RPM. I do not believe that the 550 has ever
been "certified" to the 350 Hp rating.
My engine produces 360 Hp at 2700 RPM and 36" MP as measured on a calibrated
engine dynamometer.
<<The weight of this engine is 442 pounds. The Lycoming TIO 540 weighs 527
pounds and delivers 350 horsepower at 2575 rpm.>>
Come on now Charlie. You know as well as I that the book numbers don't mean
squat. The published weights list the weight of the engine when it left the
factory and does not represent a fully "dressed" engine, ready to run with
accessories. I can say that I actually weighed my engine and ALL the parts
attached directly to it (except the prop). I fully dressed the engine,
including all accessories, hoses, baffling, second alternator, vibration
mount and 12 quarts of oil and then hung the engine from a calibrated load
dynamometer (no this does not qualify as "Dyno Tested" but I did that too).
The result was 623.12 pounds. Removing the oil, the dry weight is 599.48
pounds, measured. I have been told by Lancair that the dry weight of a
dressed Continental is around 625 pounds. Anybody out there actually weigh
one?
<<I have flown and trained in the Lycoming power airplane. I felt every
power
stroke. No piston powered aircraft engine is smoother than a Continental.>>>
I also have flown in both and I didn't notice a difference. You have a lot
more experience so, without empirical data, I will defer to your opinion.
<<Would we dare ask the maintenance history of the Lycoming's?>>
Ask away. Derek Hine and I have 500 and 600 hours respectively with good
compression. I do not pamper my engine. 50 hour oil changes, no additives
and 75-100% power all the time (except approach and cool down).
<And, if this is such a good idea, why haven't other Lancair builders
followed
suit?>
At least 8 have.
<<Regarding re-engineering and auto engine application, Brent also mentions
that "The few efforts that have been successful, like Jim Rahm's EngineAir
and the Eagle (we hope), are testament to this."
I recall an earlier discussion when Brent mentioned we needed "independently
verified data". I agreed wholeheartedly. Do we define success, as one flying
example, with less than 500 hours flying time?>>
You are right again. I should have been more specific. IMHO Enginair and
Eagle occupy the space between proven aircraft engines and auto conversions.
There are people out there who have pried an engine out of a terrestrial
vehicle, band sawed some adapter plates, strapped on a prop and "gone flyin'
". I believe their actions to be less than prudent. Enginair and Eagle seem
to be going about things properly. Time will tell if they are successful. I
hope they are.
Also Skip Slater writes:
<I'm seriously considering an
electronic ignition for my IO-540 not to add complexity, but reduce it by
dumping two antequated magnetos in favor of a completely solid state
ignition with a well- documented ability to increase power, reduce fuel
burn, give a much hotter spark, give better cold starting performance,
provide spark advance AND give me two nicely machined plates to cover the
holes where the complex, too-many-moving-parts mags used to be. If you know
of any good reasons I should not consider this, I'm all ears.>>
Sounds like you have been reading too much marketing information. The only
real performance advantage to electronic ignition is the ability to advance
the timing at low power settings and this is only on non turbocharged
engines. A magneto is an elegant, self contained, 3 moving part solution to
the ignition problem. At power settings of 75% or more it performs just as
well as Solid State Ignition (SSI), equipped with a starting vibrator (as
opposed to an impulse coupler) it cold starts the engine just fine. Magnetos
laugh at electro static discharge and electro magnetic pulse. Magnetos don't
care if you have an electrical system failure. You have to short out a
magneto to turn it off. Magnetos are popular with drag racers, people who
don't care about performance ;)
I have been in IFR conditions with a lot of P-Static and half the panel
worthless because of electrical interference. It never even occurred to me
that the mags would be on the list of equipment that wouldn't work in this
situation.
On a turbocharged airplane I would say that SSI is not worth it. On a
naturally aspirated airplane, I would only consider a SSI system that had a
magneto backup or a redundant electrical system on the airplane. Perhaps a
dedicated electrical system for the SSI that can be cross fed from the main
buss. Still, the idea that an electrical problem can be one that disables
navigation, communication and engine makes me nervous. At least with
magnetos I can fly airspeed, altitude compass and ball and not worry about
finding a dead stick landing sight NOW.
Now before I get jumped for not bowing to the reliability of automotive
electrical systems, I would just like to relate a story I say on the news
the other day. It featured a "gun" that was being tested by police that
would disable the electrical system on a suspects get away car. They did not
specify how the gun operated but it begs the questions "Would a few thousand
amp lightning discharge a quarter mile away roughly approximate the
emissions from this "gun"? Do you want to be the one that finds out?
Regards
Brent Regan
BTW. CAFE did a performance evaluation on Derek Hine's Lycoming powered
IV-P. Look for it in an upcomming Sport Aviation.
BR
LML website: http://www.olsusa.com/Users/Mkaye/maillist.html
Builders' Bookstore: http://www.buildersbooks.com/lancair
Please send your photos and drawings to marvkaye@olsusa.com.
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