This is the engine I previously wrote about some time back. It was
originally known as the ATP Turbine (Affordable Turbine Power), at the time
I visited their manufacturing facility in PA., in 2002. What follows is an
analysis I wrote about the visit. The analysis note is followed by a note I
sent them, following my visit. There is a lot of reading here, but you
might find it somewhat interesting. This engine has tremendous promise.
Like all such new endeavors, it has been slow coming to market, because
Chuck Nearhoof cannot risk the very large family machine-shop business. He
has to make the Innodyne business stand on its own.

If I had built an Express kitplane, this is the engine that would be going
into it. And if Larry Olsen had pursued this engine for his prototype
Express turboprop, rather than the PT6, he'd probably be alive today (the
high PT6 fuel flow killed him when a tank-mounted boost pump quit on a
departure, and he spun in trying to turn around). The ATP engine has fuel
flows within the normal range of piston engine fuel system design fuel
flows. What Chuck has done is re-engineer an old hot-section design, to
eliminate all of the very high-cost specialty accessories. He instead uses
his self-developed control module, and common automotive fuel injectors, oil
pump, filter, starter, alternator, etc. These parts benefit from economies
of scale, and have been proven to be extremely reliable. They cost a tiny
fraction of, for example, the cost of accessories for a P&W PT6 Fadec In
addition, the high-pressure "fogging" and "pulsing" effect of the automotive
fuel injectors provides a very thorough and clean burn; hence the
significantly improved fuel specifics (compared to most turbines. If I am
pulling 200HP from my IO360, it uses a higher fuel flow than the Innodyne,
for the same power. The Innodyne gets more fuel-efficient the higher it
goes and the faster it goes; and since it is de-rated at sea level, it can
put out that 200HP far higher than my IO360 can.

Regarding putting your certified plane into Experimental status; this is
nowhere near as simple as it sounds. The FAA will not allow a certified
plane to be changed to an Experimental-Amateur Built airworthiness
certificate. It will allow a certified plane to be TEMPORARILY placed in
Experimental -Development status. This carries with it quite significant
restrictions. There will be time limits, range limits, purpose-of-flight
limits, etc. Contrary to most folks' impressions, there are a number of
Experimental Status categories, of which Amateur-Built is just one. All of
them carry significant restrictions. For example, you could put a Sport
into Experimental-Development, in order to engineer an Innodyne engine
conversion. You would jump through God knows how many hoops, working with
Designated Engineering representatives and others (all of whom get paid by
you), in order to eventually (maybe) winding up with a Field Approval on a
one-time 337. Developing a salable-repeatable STC would cost significantly
more. Would I like to see a 300 HP Innodyne (or even a 210 HP version) in
my Sierra? You betcha. But I could probably hire someone full time to help
me build an Express or RV10, put the Innodyne in it, and spend a fraction of
what the certified-plane approach would take.

PLEASE NOTE: What follows was written in 2002. I have not visited the
plant since then, and have not researched the current Innodyne website info
to detect and resolve any conflicts. It should be clear that if any current
Innodyne info conflicts with mine, theirs should be considered the most

From: Mike Rellihan []
Sent: Saturday, May 11, 2002 5:55 PM
Subject: ATP Turbines - Visit Results

We just returned to Laurens from PA. Clearfield, PA is a hole in the wall;
and Osceola Mills is a nearby chip in the paint. We stayed in a Super 8 in
Clearfield for $55, and were given a 4X4 Chevy 4-door Pickup by Enterprise
for $35 (they were out of cars). I had been able to make reservations
online Thursday night, or we would have really gotten stuck on the car. I
only had to pay the Economy rate.

The Nearhoof name is apparently widely known around there, and I was
extremely surprised and impressed by what we found as we drove up to the
Nearhoof facility in OM. I was expecting a backyard garage operation, or
something similar. What we found instead was a multimillion dollar facility
easily five or six times the size of Northeast Maintenance. Nearhoof
Machinery is a major machine-shop operation that has been in business for 30
years, founded by Chuck Nearhoof's father. The family operation continues
under Chuck's management. The place has vast equipment, larger than
anything I've ever seen outside a shipyard. Examples are a 70-ton shaft
press, and a milling machine that is two stories high and has a 77-inch bed
plate. They employ 10-20 skilled machinists, depending on business. Some
of the things in progress were all around the place. One of the most
impressive was a pallet of forged steel donuts. Each donut was about 24" in
diameter and 10" thick. They were being turned into shaft nuts on giant
lathes. It was just incredible to see the equipment and how they used it.
They had us both sign standard non-disclosure agreements, but all the
following info is non-proprietary, public, and/or was being publicly
provided at SNF.

Chuck has devoted an area in the rear of the machine shop to the Affordable
Turbines business and his aircraft-related hobby work. In addition to the
adjacent test cell with its open ends (with protective bars), there is a
large work area where they have the test plane (the RV4 we saw at SNF). I
did not get to see it fly, as they were still putting the wings back on from
SNF, plus some other modifications including the inlet area. There is
another very large shop area that has been newly walled off from the main
machine shop. It is intended to be their parts stock and turbine assembly
"clean room". We did witness an engine start and run series in the test
cell, using the test equipment and controls in the test room. This engine
is the one intended to be the "300 HP" series, which is expected to actually
produce the equivalent of 400HP in thrust while remaining within TIT limits.
I could see the rub marks on the multiple scales that have been used to
measure effective thrust, in both tractor and pusher configurations.

Some of the more interesting aspects include:
1. The engine is actually based on a 30+ year-old turbine engine that
was developed for the military, and on which there are no patents remaining
in effect. They are currently using only the compressor and hot section,
and are machining everything else themselves. On production engines they
intend to machine everything in-house, and they clearly do have the
long-term capability to do so. One key implication is that even if they
were to decide to discontinue production in some future year, due to
unprofitability of the ATP subsidiary business, they would nonetheless
easily be able to make any required replacement part due to the long-term
major machine shop business. This is an inference on my part, not the
result of any statement on their part.
2. They had some reduction-gear parts machined and on a pallet, and let
me examine them. They are made from 6061-T6 aluminum billet, and the
machine work seemed to be first-class; parts fit was excellent. There is no
question about their ability to manufacture everything this engine needs,
other than the inexpensive commodity parts they plan to use (automotive
injectors, starter, alternator, fuel pumps, hardware, etc.). As an aside,
Chuck confirmed that on a typical commercial turbine engine, the fuel system
alone comprises one third of the total engine cost. That helps illustrate
their advantage by using the commodity parts with long-proven performance
histories in auto and industrial applications.
3. The production engines will have provisions for more external
equipment, such as a pump for a hydraulic prop, or a vacuum pump. They are
having problems getting enough variety in electric props to absorb the shaft
HP, while achieving low enough drag in low pitch to allow starting. For
example, Hartzell hydraulic props have a larger variety of blades available,
including those with less twist.
4. They have had three test-stand stoppages, and no in-flight
stoppages. The three test stand stoppages included an early-on blown
injector seal that dropped fuel rail pressure, solved by using special
retaining clips and the support ring that we've seen; a disconnected ground
wire on the test stand; and one sudden stoppage. The sudden stoppage
occurred when the prop thrust pulled so much air through the ten-foot-square
test cell tunnel that an overhead fluorescent light housing ripped out ten
nails, plus twenty feet of metallic flex conduit, and wrapped it all around
the prop. The prop was destroyed and they had to replace two chipped gears
in the reduction gear. All the parts aft of the reduction gear were
undamaged. One interesting aside is that when the fuel o-ring blew, it
sprayed fuel at 60 PSI into the exhaust, and it did not ignite; the EGT is
below the ignition temperature of the fuel.
5. Chuck has sprayed a garden hose at full stream pressure into the
inlet during engine test runs, from 2,000 prop RPM up to over 2,800 RPM.
The engine was unaffected, but they found severe erosion on the propeller
itself. They can't foresee any flyable atmospheric conditions in which
water ingestion could become an issue. A personal observation: the revised
NACA induction scoops should make hail a non-issue (for the engine!), as it
typically has too much mass to make the turn with the induction air.

They have an engine mount, with associated Lyc engine, intended for an
Express. The owner hit some adverse finances and had to delay the mount
development; they are just waiting for his go-ahead. Being the first is
expected to cost the guy in the neighborhood of $5K-$8K.

They have designed the engine and its mount to actually survive the loss of
a complete prop blade. They leave it up to the airframe designer to provide
suitable mount attach point strength. They are confident that the axial
loads won't hurt the engine. They have designed in very high axial load
capability. For that reason, they are also quite confident that the engine
will easily handle normal (non-competition) aerobatics. They can't control
related factors such as pumps, props, mount attachments, and other
builder-provided aspects.

They haven't yet been able to carry out altitude testing. They believe that
the economic performance (fuel burn per pound of thrust) will improve
further at high altitude and high ram air speeds, where the engine pressure
ratio will get much better. Their challenges include airframes and props
that will enable such testing.

They were very hospitable, even though we had been repeatedly delayed and
were late arriving at the shop. As you can see, I was highly impressed with
the whole picture that we saw. I had not formed that kind of picture from
what we saw and heard at SNF, nor from their website. Seeing was definitely

From: Mike Rellihan []
Sent: Sunday, May 12, 2002 8:28 AM
Subject: Attn: Chuck or Scott; Follow-up to Rellihan visit Friday May 10

I wanted to thank you for hosting me this past week, especially since we
were a bit late arriving. Our flight back here to Laurens on Saturday AM
went much better than expected. Winds weren't that bad after all, and only
moderate IFR. We're planning to return home to Jacksonville, FL on Weds or
Thurs of the coming week.

We were impressed by your operation, along with the development work you
have done on your engine design. I now believe that you are indeed capable
of following through with this project as planned. By capable I mean both
your personal abilities and your manufacturing capabilities, without heavy
reliance on outside parties for anything other than commodity items
(injectors, etc.). Of course, I'm assuming you have the sources for the
aluminum billets, etc. considering the scope of your shop operation.

Please take a moment to reply to a few questions for me. I didn't want to
drag out the visit with more questions, when it appeared we were holding up
the shop closure on a Friday afternoon.
1. You mentioned some additional development items such as hydraulic
pump and accessory drive. Presumably that will take time. What is the
probable real availability of the 200HP and 300HP variants? Might it be
worthwhile to offer the 200HP as the more "bare-bones" version for simpler
planes, and focus the development of the 300HP with the added accessories
for more complex traveling planes? Or will the same drive necessarily fit
both anyway?
2. Your website mentions a "members only" list. Can you put me on that
list so I can obtain the additional info? I had asked this in an earlier
note but the question wasn't answered.
3. Have you considered something like a "shared escrow" to generate
financing? For example, sell a delivery position for $1,000 (or whatever),
with half of it non-refundable (for your use), and the other half going into
a refundable Escrow account? That way the customer knows that you have
additional financial incentive to follow-through. The customer also has a
bit less at risk, yet has to show a definite commitment to a purchase.
Should their plans unexpectedly change, they could sell their delivery
position to someone else.
4. Do I correctly gather that you will be making prop recommendations
for a given airframe, along with your engine, as a result of your
development efforts? Or will you actually try to form a reseller's
relationship with the prop manufacturers and sell the mount/engine/prop as a
5. With the expected NACA duct revision to the induction air inlet, do
you think that it will preclude hail induction? In other words, I would
expect that the mass effect of hail, and maybe even some heavy snow, might
cause it to bypass the duct inlet. I haven't done much research like that
on NACA ducts. I realize that hail presents other very serious airframe
hazards, but it would be a reasonable precaution to use the NACA duct design
to prevent engine damage, and use that as a marketing plus for an engine
that can power a serious traveling airplane.
I hope you don't mind me emphasizing this; but to the extent that it is
possible, it would really be smart to contour that induction air route into
the compressor, on both the front and rear face. Maybe the rear face could
use a welded-on curved face, if it is impractical to machine the curve into
the billet (weight, cost, etc.). I would be leery of anything like fastened
vanes that could possibly come loose, and are small enough to touch or enter
the compressor. It should be a continuous curve unbroken by edges or
fasteners, right up into and through the fiberglass shroud. The ideal shape
to accentuate ram effect is a gradually tapering cross-sectional area,
largest at the outside and smallest at the compressor face. It has to be
curved both front and rear, so that the air stays attached to the contour
and is never tripped by a straight line or flat edge. It is a principle
very similar to that employed in a laminar-flow wing section, with the added
intent of ram compression. There are similar principles employed in an
efficient cooling air inlet, with the opposite intent of converting ram air
speed to a lower constant pressure, without turbulence. These require the
opposite design of smoothly expanding cross-section, but the same curvature
rules apply. As we discussed, any flat surface, any straight edge, and
especially any protrusions have a much more dramatic effect on turbulence
and effective airflow than most people realize, especially in a
high-velocity stream. All racers know that a valve seat has to have a
3-angle cut to improve airflow into an engine. Winning racers know that
they have to contour the seat so that the actual valve seating area is
almost indistinguishable from the continuous curve. The ideal flat valve
seat area is just wide enough to allow valve cooling contact. Thanks for
tolerating me on this!

That's about it for now. Please get back to me on my questions when you get
a chance.

----- Original Message -----
From: Mike Rellihan
Sent: Friday, May 10, 2002 8:05 AM
Subject: Attn: Scott or Chuck, Visit Friday May 10, Approx 2 PM

Greetings. As mentioned in our earlier exchange, I'd like to visit your
plant this afternoon. I'll have a 20-year old nephew with me. We're
presently in Laurens SC, and have been waiting for the weather to clear. I
have an IFR flight plan filed for N18767, into Clearfield PA as Chuck
recommended. I expect an 0915 takeoff and a 1230 arrival. I have a room
reserved at the Days Inn, and a car reserved with Enterprise.

I have the Mapquest maps and directions to your site. I'm guessing on a 2PM
arrival, give or take. Our hope is to see engine operation in the test cell
and see a flight. I'd also like to discuss engine operation experience in
the test cell.

We had intended to visit on Thursday but the weather has delayed us. I hope
Friday isn't a problem. I'm going to try to call you when I finish loading
some flight data, just to reconfirm.

-----Original Message-----
[] On Behalf Of Bill Howard
Sent: Saturday, October 08, 2005 2:32 PM
Subject: [BAC-Mail] Is that your final answer? Sport power upgrades

Hi all -

Every new member coming on looking at a Sport 150 keeps asking about a power

upgrade to 180...

Well, who's got the guts do to this first?

AND - it uses Jet-A!

Bill Howard


N1927W 1973 Sport 150

Beech Aero Club NorthWest Region Director

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