Diesel PA28

[POT NOODLE HORN]

Working at Elstree today and came across a pa28 with a diesel lump in the front. I was told it was the first one of it's kind as far as he new ? Watched it take off and the thing was so quiet all I could hear was a "woooossshhh" as it climbed out. The owners (Cabair) are in the middle of building another so as they say "the future's bright, the future's diesel".

(it did come back after 10mins due to a warning light coming on)

[IanSeager]

I was told it was the first one of it's kind

There's been one with BCT at Kemble for a while now.

Ian

[IO540]

Sadly, all the current diesel engined aircraft get through a lot of warning light lamps.......

I wish the makers tested their engines a bit more before selling them to people. Then I could be optimistic about the technology. No way would I fly any diesel over water or mountains at present.

[smarthawke]

Cheap fuel and not much of it but.... the motor weighs 125lb more so scuppers the Warrior as a 3/4 seater, poorer climb rate certainly to 2000 ft (despite a constant speed prop) and cruises 5 kts slower. These are the facts and figures straight from an Oxford based sales team!

Lycoming - still the reliable way forward......

[captaind]

Aircraft engines are interesting. in the past 2 decades, aircraft engines have advanced very little or not at all. However, car engines have come a long ways as far as power and effiency in the past 2 decades. For example my Subaru Impreza has a boxer engine in it, Subaru uses the boxer because it began making planes before cars. When they started making cars they already had a good engine from the planes, and since then they have stayed with the boxer style. So essentially I have a modern day aviation engine in my car, but why havnt real aviation engines followed along?

[IO540]

Ultra conservative American market preventing innovation, basically.

Certification (usually quoted as the culprit) is no problem if there is a demand for something.

[niknak]

Or more likely, development costs.

A new engine can cost millions to design, get through the rigorous testing and approvals procedure and then market,.
If you are putting it in a car or any other vehicle, more than likely you'll sell millions of them and get a rapid return on you investment.
If you put it in an aeroplane, you might, if you are very lucky, sell a few hundred eac year, and you'll be waiting a very long time to get your money back.

I mentioned this to a freind who was formerly a Lotus bodywork and engine design engineer and is now working on a brand new concept car with a new small but specialist firm.
He was suprised and intrigued that none of the aircraft manufacturers appear have attempted to work with the automotive industry (or vice verca) to reach a compromise, and intends to pass the idea on for further thought.

[MikeeB]

<snip>
For example my Subaru Impreza has a boxer engine in it, Subaru uses the boxer because it began making planes before cars. So essentially I have a modern day aviation engine in my car, but why havnt real aviation engines followed along?


I had a WRX for three years. In terms of value for money and function, it's the worst car I've ever owned. The engine contributed towards that due to it's "lumpy" power delivery. Never realised the origins of the subaru boxer engine before. It was also very very thirsty, returning an overall average of 23mpg.

[White Bear]

“Ultra conservative American market preventing innovation, basically”

I0540,
The truth is the reputation of diesel engines was destroyed in the U.S. by GM 20 years ago. (If you wish to know more, Google the 350 GM diesel engine) Even today with modern diesel engines so much better than ever, manufactures have, in the largest auto market in the world, a hard time selling just a few thousand nationwide for use in cars.

As not everyone has an artificial price difference between petrol and diesel fuel, and with the added weight of a diesel, and no power advantage, this is really no reason to change from what is working now.

But if you want to make equally cutting comments about the petrol aero engines most of us are forced to use, and ask the very reasonable question; why do the authorities insist we still use 1930’s technology and why do they make it so difficult to update, retrofit or modernize them?, then you’ll find you will have my full support, just as you do about GPS usage.

P.S. I loved your last rant about the CAA; I particularly enjoyed your use of ‘still flying rag winged aircraft’, wonderful stuff!


Captind,
As for Subaru manufacturing aero engines, well Nakajima did do so, but I am not aware of any flat 4 or flat 6 engines, plenty of radials, but they aren’t the same thing. So where this story of Subaru having a “aero engine available so they used it in their cars” came from I don’t know. By the way IMHO “flat” engines and “boxer” engines may look vaguely alike, but once again they are not the same thing. In a true “boxer” 2 pistons come together from opposite directions, in the same cylinder, to form the combustion chamber, and have 2 crankshafts.

Regards,
W.B.

[BigEndBob]

Surely whats driving the diesel engine development is the possibility that Avgas aint going to be available in the future?

[Speedtape]

The current crop of aviation diesels would be more reliable if they ran on Diesel instead of trying to run them on Kerosene (Jet A1). But then you'd have to pay diesel prices for the fuel and that would negate the cost benefits.

[wbryce]

For example my Subaru Impreza has a boxer engine in it, Subaru uses the boxer because it began making planes before cars. So essentially I have a modern day aviation engine in my car

The amount of times i've seen or heard of a scoobys engine blow up! maybe its best the older style engine are still in use :E

[IO540]

The current crop of aviation diesels would be more reliable if they ran on Diesel instead of trying to run them on Kerosene

That suggests you have inside information on what is causing the Thielert engine to repeatedly pack up :O

You may be right; I have no idea.

The debate about car engines in planes is much older than I've been flying. I am not convinced car engines would be reliable in planes. A car engine rarely runs at more than about 30% power. At 75% power most decent cars will go fast enough to land the driver in jail on first offence and few roads are good enough for more than a minute or two of say 140mph. Most of the time the engine is doing say 10-20% power. No wonder they are super reliable. Those that get properly thrashed (rallying, racing) don't last long.

Lycomings are reliable, and are efficient in as much any engine will only deliver the fuel's chemical energy, and if one can run it just after peak EGT that is the best one can get. What Lycos don't have is good thermal design, so they need careful management otherwise one gets cracks... they also suffer from poor QA nowadays.

Diesels in GA stand and fall almost entirely according to fuel taxation. I do long flights into Europe and can see other factors: One can get tax-free AVGAS in most places upon the production of an AOC, levelling the price with Avtur (and any serious operator can get an "AOC" if he wants to). One cannot really get Avgas outside Europe, but avtur is everywhere - this doesn't bother the average Euro PPL who does short burger runs! Spain will sell you tax free Avgas if plane is business owned. Etc.

So the pro-diesel factors are even fewer that one might think.

And given the poor reliability, I can't see why anybody would bother. OK in a twin I suppose.

FADEC on a Lyco would be interesting! A turboprop is THE way to go though.

[captaind]

wbryce-

Where did you get that information from about the subaru engines? If that is happening, these must be people who mod their engines. Subaru is one of the most reliable vehicles in the US, for 2004 in reliability it was Subaru, then Honda, then Toyota. I'm sorry you must be thinking of another car. Not to mention my mothers 1986 subaru GL is running on the original engine with 535,000 miles and her "newer" subaru a forester with 218,000 miles on her... original engine, all original parts. Do some serious research before posting something like that

[TheOddOne]

A turboprop is THE way to go though.

Nice thought, but I looked at the Cessna 208 some years ago. There were competitive direct operating costs bandied about but when I enquired about cost per hour for the engine, it didn't stack up. Assuming you make it trouble-free to overhaul time (which is quite likely with the PT6) you need a new 'hot' section after 3,500 hours at in excess of £100,000. This'll only really be viable if you can do Public Transport IFR in it and as we all know, the CAA are still reluctant to go there. Great pity.

Dunno about a turboprop in a PA28 - is there one small and light enough, gearbox & all? What would the total cost of ownership per hour look like, the only meaningful figure in my opinion?

Cheers,
The Odd One

[Croqueteer]

Speedtape, an aircraft is allowed to use red diesel, currently about £2 a gallon.:O

[IO540]

Theoddone

Flying in the UK, you would save up most of the HSI cost from the fuel price differential. Is it really £100k? £50k was what I've heard for a PT6.

Smaller engines seem better than a PT6. The Grob 140 uses an Allison (R/Royce) 450hp turbine, and being unpressurised the airframe maintenance costs are far lower. The Extra 500 looks good too.

The purchase prices are high though and I agree about utilisation. But... look at the huge operating costs of a piston twin, over many years, and a single turboprop gives you about 5x the reliability of a piston twin :O

[JW411]

There is no reason that I can think of why you cannot run diesel engines on Jet A1. When I was in the RAF (30 years ago) I used to run the station gliding club in my spare time.

My nextdoor neighbour was a boffin for Esso at Harwell. I asked him to seriously research using Jet A1 in diesel engines. His conclusion was that all we had to do was to add ½% by volume of any old oil, just enough to ensure lubrication of the injector pumps, and that was all we had to do.

We ran tractors, winches and retrieve vehicles on this concoction for years and years without a single murmer.

I wonder if the new aircraft diesel engines are adjusted to do without the "½% by volume" of any old oil requirement?"

PS. Have the CAA forked out for the prop they bent on the diesel PA28 at Shoreham yet?

[IO540]

Aero diesels do run on jet fuel. Nobody would buy one otherwise.

[JW411]

I am well aware that they run on Jet A1 - that is the whole point.

I was responding to an earlier poster who suggested that they should run them on diesel fuel and stop trying to make them work on Jet A1.

I am merely trying to point out that there is no earthly reason NOT to run them on Jet A1.

[justinmg]

Is there much point in going deisel for a piston engine. Should we not stay where we are until turbines are ready (which may be close if you believe some). Changing to another piston variant now, could be deemed a halfway step, and an expensive one at that.

[smarthawke]

As far as I know the UK Thierlets are only allowed to run on JetA1 ie not use diesel. Of course whether that changes if the engine is certified by EASA and the rest of Europe can use it I know not.

[Cough]

Speaking of turbines that are close, ever looked at innodyn (www.innodyn.com)? Ok so they aren't for certified aircraft, by me old man's looking at putting one in a RV10 when he gets round to ordering it...

[IO540]

Turbines are tops for reliability but they do have a higher fuel consumption. A piston plane converted to a turbine tends to lose about 1/3 of its range.

Presumably this range loss depends on the height one can cruise at (i.e. the TAS gain) - I suspect most unpressurised people will not want to fly at FL250 because one cannot (well not legally) use a cannula; one needs a full mask and the o2 flow rate is then pretty high. Also while most passengers appear content with FL140 without o2, they WILL have to be on it at FL250 and if carrying 4 people this ups the usage 4x.

There are some fantastic American exp-category planes, which have basically nothing wrong with them. It shows how backward certified GA is.

[Sunfish]

DO NOT RUN AN AIRCRAFT DIESEL ON AUTOMOTIVE DIESEL UNLESS THE MANUFACTURER ALLOWS IT!

There are all kinds of grades of diesel and if you get "summer" diesel fuel with a higher cloud point, you can get into real trouble on a cold day. Diesel fuel contains waxes. These waxes can solidify into little particles that will quickly block your fuel injectors - if the fuel is cold enough and the injector final filter fine enough.

Jet A1 has had the waxes mostly removed which is one of the reasons it has poor lubrication properties compared to diesel, so don't run jet A1 in your diesel car either or the injection pump is going to get scored real fast.

We sometimes "manufactured" diesel fuel when the refinery couldn't provide it by blending jet A1 with lube oil base to get the required lubricity.

As for certified GA being "backward" there are a few points I\'d like to remind you about.

- Aircraft engines spend their entire time operating at 55-100 percent of their rated power. Car engines spend about 10 percent or less at anything like this percentage. The "reliability" you see in car engines is illusory. To get reliability you need to drop power ratings to less than 50 BHP per litre instead of the 100 bhp per litre many car engines turn out.

- The benefits of variable valve timing, overhead camshafts, electronic ignition, electronic fuel injection are not going to produce all that much benefit on a motor that turns 2300 - 2700 rpm day in and day out. True, better fuel injection would be nice so that the engine can be run lean of peak and knock sensors to prevent detonation would be nice as well. Be prepared to have two alternators and three batteries if you want this.

- Then let the whole thing stand for months at a time in the rain and expect it to work first time.

[Rod1]

“To get reliability you need to drop power ratings to less than 50 BHP per litre instead of the 100 bhp per litre many car engines turn out.”

The Rotax 912S provides 100hp on 1.3L cap with a very good reliability record. It will be interesting to see if the new range of up to 300 Hp petrol engines are as popular.

Rod1

[OlaM]

An upcoming Jet A1 engine worthy of mention; Deltahawk.

http://www.deltahawkengines.com/

Comes in 160-180-200 HP, dual charged, two-stroke, nothing electrical (apart from alt and starter), no valves, no cam, no pushrods.

And after many years, finally not vaporware either as the first batch is being shipped. :)

They've got some impressive fuel/performance numbers posted on the site, but I'm looking forward to what the first customer says.

Disadvantages include weight (around 400 lb installed, including peripherals), the need for fuel return + ventilation, purchase price.


edit: And no, it's obviously not certified yet.

[IO540]

Is there any reliability data for Rotax engines, comparing them with the old Lyco engines for example?

Anecdotal evidence suggests Rotax are far less reliable than the old Lycos. They do however occupy what is for most part a different part of the market. A failure of say an IO-540 is going to bring down a 4- or 6-seat plane of reasonable size, and it will certainly get noticed. A failure of the average Rotax will quite likely bring down something which can land and take off from just about anywhere, so the engine failure may go unreported.

[Genghis the Engineer]

Reliability of Rotaxes is poor by reputation, however that is heavily biased by the early 2-strokes, which whilst cheap, light and cheerful don't have a fantastic ratio of hours per failure. The first Rotax 4-stroke, the 508, made the 2-strokes look good.

The new models however, the 912/914 series seem from what I've seen to be giving equivalent reliability to the Lycontinentals, at rather better cost and weight. TBO is shorter, but cost/hr still wins hands-down. That said, I've not seen any verified stats, and you'll still see a certain failure rate on homebuilts/microlights/owner-maintained aircraft where the operating environment is more hostile to the engine than that of a certified aircraft/engine combination.

So far as Diesels in little aeroplanes are concerned, it's interesting to attend one of Mark Wilsch's talks on the subject which he does at the occasional conference. He's clearly one of the biggest advocates of Diesels, but explains very clearly why he believes that below 140hp-ish there's no future for Diesels, and that there's no way his technology can compete with the abilities of the 912/914 series. Since it would clearly be in his interest to prove otherwise, I assume he's being honest!


Having flown both a lot (that is Rotax and Lycontinental), I'd certainly rather be behind a Rotax, which when well set-up is smoother, quieter, less thirsty, and generally needs "nursing" less once you've got the CHT up for take-off power.

G

[unfazed]

IO540 - Ultra conservative American market preventing innovation, basically.

Had to laugh at your comment above

Burt Rutan?
X Prize ?
Men on the moon ?
GPS Approaches ?
Full weather download capability for equipped aircraft ?

GET REAL !