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Editorial: Sun n Fun '97 Reality Check

By Tracy Crook. Originally published in the Rotary Aviation News, Issue 2, 1997

I always enjoy Sun ‘n Fun even though it takes me about a week to recover from it.. After it’s over, only the memory of engines, planes, neat stuff and especially the great people you meet remains. The greasy fly-in food, sleeping on the ground in a tent and the infamous Port-O-johns are quickly forgotten. Well, fairly soon anyway.

After seeing it about a dozen times, the airshow itself looses it’s attraction. Except for a few standout performances like Sean Tucker’s, it’s mainly a chance to see the indoor exhibits while the crowds are outside. The last hour is wave after wave of warbird fly-bys. This spectacle must bring back a lot of memories for those who experienced these sights and sounds when both they and the airplanes were young. I was born too late to remember them. Its the sound of helicopter rotor blades and jungle heat that remind me of military aviation and I would just as soon let those memories fade.

What’s New - What’s Gone….

Major fly-ins like Sun ‘n Fun also serve as a preview of things to come in home built aviation. This peek into the future includes everything from subtly ingenious breakthroughs to blatantly obvious scams and everything in between. Naturally the thing I look most closely at is engine developments. The news in that department was mostly disappointing this year. There was a surprising lack of presence among the commercial vendors. Formula Power bailed out of the market and sold the rights to their product line about a year ago. Frankly, I’m not sure what the buyer got for their money anyway. Formula never really developed anything on their own. Everything they sold was supplied by other companies. By the time they marked up the price enough to stay in business, the engine ended up costing more than a Lycoming. As I have said in the past, I don’t believe the market for auto engine conversions is going to “take off” until the price makes sense.

I ran into Reiner Hoffman of Stratus Engines at the fly-in but he did not do a commercial display as far as I know.

Most ominous, was the absence of NSI. These folks have been showing the world’s most beautiful static display engines for years now. Their prices were even higher than Formula Power but at least they were developing some of their own hardware, especially the PSRU. I thought it was the price which kept them from showing up on actual flying planes but apparently there were other factors at work. I do not have any official word on the fate of NSI so all I was able to learn was based on hearsay and rumor. According to the flightline chatter, NSI has left the market taking a lot of builder’s engine deposits with them. The rumored reason for the sudden departure was a rash of failures of the PSRU sprag clutch which they use for torsional vibration control.

Remember this is just rumor. Time will tell what actually happened.

Loose some, Gain some …

On the positive side, Eggenfellner Advanced Aviation showed up with a very large outdoor display. In the past, Eggenfellner’s only presence was a plane with one of their belt reduction drives installed on an EJ-22 Subaru. I did like seeing a company fly in with what they sold.

They appear to have abandoned the belt drive in favor of gears. Their new PSRU is based on a gear set from an unspecified Japanese manual transmission which looks strong enough to do the job. Four gears and a jackshaft are used just like in a normal automotive transmission. For those of you who are partial to right hand props, this arrangement does not reverse the prop shaft rotation. The housing is of CNC machined aluminum which looks strong enough without being overly heavy. The drive is splash lubricated from its own sump using synthetic 90 W gear lube.

For torsional vibration, Eggenfellner used what is known as a gebo. This is a rubber coupler commonly used in the drive shaft coupling of BMW and Mercedes automobiles. I’m looking at one of these devices myself and may use it in later versions of my own PSRU. Obviously, I think its a good idea.

Instead of a bellhousing, Eggenfellner uses 1 inch thick G10 fiberglass laminate board to adapt the gear drive to the engine. This is the same type of material used to make high quality circuit boards.

A ‘Cool’ Gearbox

The reason given for using this material was to thermally isolate the drive from the heat of the engine. I don’t doubt the strength of the fiberglass laminate but I thought the reasoning behind the need to thermally isolate the drive was questionable. The engine it is designed to mate with (Subaru EJ-22) is water cooled and should run in the neighborhood of 180 deg. F which the gear lube should be quite happy with. Even with complete isolation, I would guess that the gear drive itself would run at about the same temperature when run continuously at high power settings.

This would be even more likely when the cooling system is arranged like mine. My PSRU is exposed to the hot air (about 150 degrees F) from the back side of the radiators. If the temperature rise of the gear drive is more than 30 degrees above ambient (very likely), being thermally coupled to the engine would actually make the drive cooler in this case. Not a big deal here, I’m sure Eggenfellner’s arrangement will work fine.

Engines Too

In addition to the PSRU, Eggenfellner will furnish the complete powerplant. The engine is the previously mentioned EJ-22 equipped with an electronic fuel injection, ignition system and wiring harness. They even include an exhaust system complete with muffler.

The performance claims are refreshingly realistic compared to other companies offering the EJ-22. The rating of 130 - 135 HP is a lot closer to reality than the 160 - 200 HP quoted by others. The price is a more realistic number too. The complete package is $8000, about half what others have tried (and apparently failed) to get. I hope Eggenfellner makes a go of this business, they are doing a lot of things right.

Industrial Art

As I was walking toward one of the indoor exhibit buildings, an odd looking structure of stainless steel caught my eye. A casual look at the thing was enough to reveal that it was supposed to be an engine of some sort. A poster nearby announced that it was a revolutionary powerplant design by a company called Eagle Condor International. Great name, no? When asked what the principle of operation was the company representative gave a smoothly polished 45 second dissertation which made a lot of fantastic performance claims but said nothing at all about how it worked.

On closer inspection of the prototype which consisted of a disk shaped housing with a protruding shaft and an amazing number of thick wall stainless steel pipes sprouting from it, it became obvious that I was looking at nothing more than a piece of metal sculpture. The only question was, why would they call it an engine and pay the commercial display rate at Sun ‘n Fun to show it? The answer came when I was eventually asked if I would like to become an investor in Eagle - Condor. Who wouldn’t? L