Marc Wiese wrote:
I know this is not of rotary interest, but it has some interesting
points in it we should keep in mind. I hope a semi-professional rotary
conversion could be as appealing and economical. Read it FWIW......
-------------------------------
Subject: The diesel report
From: Thomas Borchert (EDHE) 100137,2113
All,
Well, I've flown the diesel Diamond and spoken at length with the people
at Diamond. I have yet to talk to Frank Thielert, maker of the engine,
but here's my preliminary report.
First, keep in mind I'm writing this from a European perspective, where
- Avgas is 1,70 $ per liter, Jet A1 and car diesel is 1 $ per Liter (3.8
liters to a gallon) - noisy aircraft will cost you BIG TIME in landing
fees
The short version is: I am very impressed.
I flew the Diamond DA 40 TDI (turbo diesel intercooler) composite
four-seater with the Thielert Aircraft Engines TAE-125 out of Wiener
Neustadt near Vienna, Austria, running on Jet A1. Some observations and
information from my interviews:
- I wouldn't have thought one-lever-operation is so convenient. The
engine basically has a power lever connected not to the engine but to
the electronic engine control units (ECU, two for redundancy) and a
gauge showing percent of engine power. That's all you really need. Ok,
there's RPM and the usual temps and pressures indicated, too, but that's
just for fun - all of that is controlled by the ECU software. Basically,
you just set "go fast, go slow" (and accordingly "use much fuel, use
less"). A setting of 100 percent power continuous is permitted. The ECU
will detect "hamfistedness" and correct for it by, e.g., delaying power
application a little. A pre-takeoff check is to press the button for
"ECU test", which will then start an internal test cycle. The engine is
running very smoothly and has "punch" when applying power.
- The engine is adapted from a Mercedes A-class common rail direct
injection diesel. It has an intercooler and a turbocharger. A reduction
gear box reduces max engine RPM of about 3900 to prop RPM of 2300
maximum. This gear box shields most of the diesel-specific vibration
from the prop (Paul, the spikes in the spectrum of the engine are more
pronounced because of higher compression, but the gear box does away
with most of that. Also, the engine is relatively benign to start with,
regarding vibration). The aircraft is shielded by special engine mounts.
Vibration and noise levels in the cabin are noticeably lower than in
your average Lyc or TCM four-banger. Thielert adds/changes about 140
parts on the original car engine, including the crankshaft. Redundancy
and fail safe mechanisms all conform to certification standards. The
engine runs both on Jet A1 and diesel. The DA 40 TDI will initially be
certified for Jet A1 only, since there are no questions about fuel
quality standards there. Diesel certification will follow a few months
after.
- Power is 125 hp, which might seem low, but... The Lyc DA 40 is driven
by an IO-360 with 180 hp. The diesel has 125 hp, but is running at a
lower RPM and with a bigger prop, thus being much more efficient. They
figure an equivalent hp of 160. There is no significant difference in
take-off run and climb rate for the two aircraft - until you reach 3000
feet or so, when the turbo in the diesel engine is clearly winning.
- Cruise is most efficient higher up, due to the turbo, of course.
Figure on something like 140 knots true with a consumption of about 17
liters per hour.
Well there goes the fantastic claims of high MPG for diesels.
17 liters per hour is 4.5 gallons an hour. Given the low drag
and the higher prop efficiency of the Diamond this is not out of line
with most gas engines. To give you another data point Klause
is cruising at 200 MPH and burning four gallons an hour with
his O-200 Varieze. PL
Diamond's financial department will make you a neat
calculation showing that for a five-year leasing contract in Europe, the
fuel savings alone will pay for the leasing rate at 400 hours flown per
year.
- The engine initially has a TBR of 2400 hours - R stands for
"replacement", which is what you'll do. Price for a new one should be
around 20,000 $.
- The DA 40 Lyc is built in Canada and is offered in the US. The DA 40
TDI will be built in Vienna and will initially be certified only in
Europe, not in the US. Certification is expected by September/October.
IOW, you'll be able to actually buy and get a diesel powered aircraft in
two months, production backlog notwithstanding. Diamond is shying away
from introducing a new engine in the US market again, after having
suffered a lot with the Rotax-powered Katanas. Thielert, OTOH, partners
with Superior Airparts for engine support. The DA 42 Diesel twin, to be
certified by end of 2003 (see below), will be certified in the US, too.
- The TDI is about 15,000 $ cheaper than the Lycoming version.
- The Mercedes engine block is made of aluminum, which makes it so
light. Thielert is working on a V8-aluminum block from Mercedes to make
a 310-hp-engine. Rumors have it he's also working on an intermediate
220ish hp power plant.
- Diamond has big plans and, IMHO, chances at succeeding. They want to
be the top single engine manufacturer "soon" and are ramping up
production quite a bit. The DA 42 twin diesel should be certificated by
end of 2003 - a four-seat light twin consuming 35 liters of Jet A1 per
hour (both engines
combined!) going 200 knots, with a price tag of 370,000 $. Cowlings for
Lycoming engines have been made <g>. Also, they are working on a
four/five-seat airframe for the 310-hp-diesel AND a pressurized
single-engine jet to be presented by 2005. They are very excited by
all-glass-panels and have seen prototypes of "a big avionics
manufacturer WAY cheaper" than the Avidyne Entegra. You can probably
guess who'll announce that stuff by next year. I've been told amazingly
low prices for a full two-display PFD system.
Ok, that's all I can think of at the moment. Questions?
Thomas Borchert (EDHE)
If the FAA certifies this Mercedes A class engine they will also have to
certify MecanAir's Mazda based 13B rotary.
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