Diesel Powered Cessna 182 tested

[Chris N5CWM]

This is a clip from an aviation news site:

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DIESEL-POWERED CESSNA CROSSES THE NATION

Recognizing that the long-term availability of avgas looks bleak, an

international consortium flew a Cessna 182 recently from Daytona Beach,

Florida, to Carlsbad, California, in 16 hours running on Jet-A fuel.

The 230-hp SMA SR305-230 turbodiesel engine was tested at 100 percent

power the whole trip and showed a 40-percent increase in range over

regular avgas engines, according to Riley Aero International, the

company

that is pursuing a supplemental type certificate (STC) for the 182. The

company also said the fixed-gear airplane flew at 153 knots at 12,000

feet,

compared to 139 kt for a stock 182 and ran much quieter. FAA

certification

for the installation is expected early next year. Hartzell, meanwhile,

is

working to certify propellers for the engine. Other manufacturers,

including

Maule, Socata, and Cirrus, are evaluating the engine conversion. Riley

estimates the cost of the upgrade at $110,000, including prop and a

full

authority digital engine control (FADEC) system. The target TBO is

3,000

hours. AOPA staff serve on several committees studying alternative

fuels.

New engines such as the Cessna's represent another approach to the

problem.

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Pretty neat idea. Hope the idea takes off! (Pun intended)

 

[The patriot]

I'm just an amateur here....but

Do they change the pitch on the prop, or would they go to a different gearbox to do the conversion?

I'm just thinking the RPM range is quite different on the two engines.

Eric

 

[Chris N5CWM]

Eric that's a good question.



I am pretty sure though that the diesel

operating RPM is close to the current

General Aviation gas engine operating RPM.



The 182 usually has a Lycoming IO540

rated at 230 HP at 2,450 RPM. The 540

stands for cubic inches! Most

general aviation gas engines are Lycoming

or Continetal flat 4 or flat 6 configuration.

A Lycoming IO-320 is a 320 cubic inch 4

banger! Usually redline is around 2500-

2600 RPM for these engines, I am guessing

because of the large reciprocating mass.

The only common gear-driven gen aviation

engine is the GTSIO-520 by Continetal.

Too many RPMs and the tips of the propeller

blades go supersonic and contribute to a

lot of noise on takeoff.

 

[Un-Hemi]

Up until 1986, when production was interrupted, all 182s were powered by Continental O-470s, except the 182RG, which used an O-540 Lycoming because of space limitations with the retractable gear. By the time Cessna revived production of the 182 a few years ago, Lycoming was part of their corporate structure. Continental engines were history.



The O-470S (and previous) engines were rated at 230 HP at 2750 RPM. The later O-470U engine was rated 230 HP at 2400 RPM, but used higher compression to achieve its output. Yes, the O-470U is slightly quieter at takeoff when heard from the ground because of its lower prop tip speed. The O-470U also suffered some cylinder head heat problems because of its higher cylinder pressures. The lower compression O-470s run quite nicely on autogas.



Patriot, there is no gearbox on either the stock 182 engine, or the diesel; the prop is mounted directly on the crank flange.



This diesel aircraft engine was developed initially by Renault. I suspect that Renault is part of, or has been absorbed by SMA. It's been around for a while, and is leading the field in development.



O= opposed

I= injected

G= geared

T= turbocharged

S= supercharged (mechanical)



It's still a lot of dough for the conver$ion. At 100 hours flying a year, how long does it take break even? An overhauled O-470 is, what, $25,000? Ya can do a lot of flying for the difference, even if avgas goes to $5/gal. The price must be more reasonable before this diesel makes any kind of market penetration.



I'd still like to have a reasonably priced diesel in my homebuilt, though.

 

[The patriot]

Originally posted by TommyTurbosaurus





The O-470U also suffered some cylinder head heat problems because of its higher cylinder pressures. The lower compression O-470s run quite nicely on autogas.



Patriot, there is no gearbox on either the stock 182 engine, or the diesel; the prop is mounted directly on the crank flange.

I heard they werent too much of a problem as long as you watched your gauges (EGT) and didnt lean it out too much.

Maybe I have my engines mixed up though, like I said, I just dabble in it.

Thank you Tommy, and Chris for clarifying this. I'd like to fly some day, but for now I'm mostly looking at home built experimental stuff. Most all have a two stroke Rotax (or something similar) and a gear box.

Eric

 

[Un-Hemi]

You're right, Eric. The O-470U just wasn't as tolerant of mishandling as its older brothers. I owned a 182N with an R engine, and in 1995 put more than a few hours on a 182Q with a U engine. I really couldn't tell much difference in performance, except that the older engine really sounded like it was doing something on takeoff at 2750 RPM. On the 182Q, you could leave the prop control at 2400 RPM all day and just move the throttle in and out for power adjustment. I preferred to bring the prop back to 2300 RPM just to make it a bit quieter in cruise and give the prop governor something to do.



Don't wait too long to try flying, Eric. It's not getting any cheaper or easier, notwithstanding the new Sport Pilot category. It does demand a commitment to the challenge; it's not just a casual pastime. I guess that's why there aren't more private pilots!



Cheers!

Tom

 

[Wheaties]

So how do they keep the weight down on this diesel aircraft engine? Hasn't that what has always kept diesels out of aviation?

 

[Un-Hemi]

Well, the Renault Diesel is a horizontal 4-cylinder air-cooled turbocharged engine. From the pictures I've seen of it, there are some pretty good studs holding the cylinders onto the case. The engine they intend to replace in Cessna 182s, the 230HP 6-cylinder Continental O-470, weighs approximately 455 lbs, so they have lots of allowable weight to play with. Note that the SMA diesel is rated 230HP takeoff, and 200HP continuous. If it were capable of 230HP continuous, it would probably be much heavier.



Here's the link to find out more about the SMA diesel:



http://www.smaengines.com



Fly at it!



Tom



edit: Interesting that the site doesn't appear to respond. I'm using IE5, if that means anything. Netscape 4. 7 doesn't work either. Maybe they're out for lunch.