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.

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.

Speaking of turbines that are close, ever looked at innodyn? 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...

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.

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.

“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

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.

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.

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

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 !