| Hi Gary,
Since I have actually completed a successful rotary installation, I would like to comment on the rotary engine option.
First, addressing the negatives,
1) Apex seals - The apex seal issue has been solved long ago and is no longer an issue, unless the engine is over-boosted and allowed to detonate; if this is a concern, do what the boosted guys do and go with the oversized 3mm apex seals. Even if the apex seal issue was still an issue, losing an apex seal is equivalent to burning an exhaust valve. The engine will still run, just be down on power.
2) Insurance - Obtaining full-coverage insurance has not been an issue for my ES,
3) Complex Systems - Not sure what you're referring with complex systems (running EFI which also handles ignition); Yes, I'm running 6 coils, but that provides redundancy, also running dual alternators/batteries (Z-14 design) same as many others.
4) weight is virtually the same as IO-540 (to the best of my recollection, my ES weighed in at 2080#), 5) Cooling drag - I will concede this one, but this can be minimized with careful cooling design and the use of cowl flaps. The P-51, and others, were liquid cooled. As I recall, the Voyager was liquid cooled and it made it around the globe non-stop.
5) Rotary engine's exhaust is loud - Agree, but this can be handled with a turbo, a good muffler, sound insulation, and/or an ANR headset.
As for the rotary's positives:
1) The rotary is the epitome of the KISS principle. The 20B (3-rotor) rotary engine has only 4 moving parts (3 cast iron rotors and an eccentric shaft). There's no camshaft, cam gears, rocker arms, intake or exhaust valves, pushrods, lifters, valve springs, keepers, connecting rods, caps, or bolts, piston pins, etc. - If it isn't there, it can't break.
2) 350hp (n/a p-port 3-rotor)
3) While parts are not exactly cheap (by automotive standards), they are much cheaper than certified a/c parts. The typical overhaul cost for a rotary engine is less than the cost of one jug for a certified engine.
4) Millions of rotary cars have been built; the rotary engine is well proven technology.
5) Cruise Fuel burn is for my p-ported 3-rotor is14.5-15 gph, 23 gph in climb mode. However, the rotary can burn mo-gas.
6) No concern with shock cooling. Just pull the throttle and descend, no worry.
7) No hot-start issues.
8) Comes stock with 2 plugs/rotor, providing redundancy
The stock rotary engine redlines at 9000 rpm. I typically cruise at 5200 rpm. Since the rotors turn at 1/3 crank speed, the rotors are only turning 1733 rpm in cruise. If/when I want to go faster, I run it at 5900 rpm, the point on the rpm curve where there is the least amount of bearing load. Even at 5900 rpm, the rotors are turning less than 2000 rpm.
I'll be the first to admit that the rotary route is not for everybody, and I'm not trying to convince anyone to go down this path. Personally, I'm extremely pleased with my choice of engines and plan on flying it for many years to come. All I ask is that it is given a fair evaluation.
Mark S. Austin, TX On Sat, Jun 4, 2011 at 8:52 AM, Gary Casey <casey.gary@yahoo.com> wrote:
Lot's of interesting comments on the subject of alternate engines. I was convinced I was going to use an automotive V-8 at one time, but the last straws were the difficulty (or impossibility) of getting insurance and the low (or impossibility) of resae value. As someone said, the resale value would likely be the same as an aircraft without an engine. And my analysis showed that the installed cost would be about the same (or more) then for an aircraft engine. But the internals of any of these engines are robust and should able to tolerate high continuous power. My conclusions - opinions of the disadvantages:
V-8 with reduction gear:
Heavy - about 150 pound penalty
Complex installation and systems
Slight fuel consumption penalty
V-8 engine direct drive turbocharged:
Heavy - about 75 pound penalty
Complex installation and systems
Rotary engine:
Very complex installation and systems
Heavy - up to 50 pound penalty
Potentially fragile apex seals
Hgh cooling drag
Noisy
Significant fuel consumption penalty increases the weight penalty
Turbine engine:
High initial cost
High fuel consumption negates any weight savings
Misc. opinions: The liquid-cooled V-8 dates back to about 1918 when Chevrolet built the first mass-produced one, so it's technology is even older than the air-cooled engine's "30's technology" that someone mentioned.
Gary Casey
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