Diesel Engines - Specifically the SMA offering

As I recall:

1. Diesels need a CS prop as the power band is very narrow. This immediately adds a lot of money to the installation cost if the Avgas version didn't have one. Hence the 182 logic I guess.

   1. Diesel is 10% heavier than AVGAS so you can carry less of it for same W&B.
   2. In the UK it is taxed at 57p per litre +20% VAT for private use. This killed our market.

In the UK it is taxed at 57p per litre +20% VAT for private use. This killed our market.

I thought that any "business" or "training" use was exempt, so if you fly to Airport X and fly an ILS and you call it a practice flight, you don't pay... ? Or does there have to be an instructor in the RHS? Has this ever been defined?

Presumably, anyway, this creates a huge incentive, on a plane with any half decent range, to fill up outside the UK. This will be worth doing only if you are based on the south coast however.

I don't know what the latest is on the SMA... Socata played with it for a few years (they got Britten Norman on the Isle of Wight to do the R&D) and there is a TB10 and a TB20 flying with it. Thielert obviously got ahead early on, on the back of Diamond's high profile. It should be a good retrofit-market engine, with IO540-compatible mounting points.

The SMA engine is very expensive, starting at €90k + VAT + accessories. Until recently it had dismal performance at altitude. They don't want to pursue STCs themselves anymore due to cost and lack of experience. Chicken hen problem.

But most diesel conversions have been c. €80k or so, aren't they? I think what has happened is that the Marketing people decided to go after the 500+hr/year FTO market only and priced it at the absolute very top which they thought anybody would pay. A Lyco IO540-C4 is c. $60k brand new, and reportedly one can buy them from some "cost plus" outfit for a lot less.

Also, isn't it turbocharged?

I vaguely recall there were problems starting it at altitude (a cert requirement) but that this was later sorted.

The Socata man involved in the programme told me they had severe vibration problems which they never resolved.

The raw engine is €90k already, you need quite a bit extra like oil coolers. It's significantly more than an avgas engine of comparable horsepower. 2400h TBO is a great start (how did they manage to get this, I rather don't want to know) and they hinted something about 2800h soon and then 3000h later. You can believe these statements like people believed Thielert who "guaranteed" fixed maintenance costs per hour.

The problem of the engine is the turbocharger. It needs a lot of manifold pressure (i.e. turbocharging) even at sea level to make its power. Initially they had a standard turbocharger from one of the two GA outfits but it was too weak and thus the bad power at altitude. They then designed their own turbocharger which is a lot better (and bigger). However, it still loses power at altitude quickly, much more so than a turbocharged Lyco/Conti which makes it uninteresting for high altitude cruisers.

For the same reason there is no chance to get bleed air for pressurization from this engine. Turbo diesels like manifold pressures of 90" and more so turbochargers are already quite busy down low and don't have the power to perform well at altitude.

I wonder how they did that in the 1940s Junkers designs, probably the best aero diesel until today...

SMA launched the second generation only this year and that is the engine that you will find in the new C182 jet A.

It is a huge improvement over the first gen. The engine weighs approx 445lbs dry. Which puts it in the 6 cylinder replacement category.

SMA for now only wants to focus on the OEM's. Thus the price is artificially kept high. I think that once they start gaining momentum they will drop the price to 50-60k ish + you will need to pay somebody for the work and the STC.

A 180bhp C172 runs at 7gph and can run on mogas (roughly € 1,70 per liter). An overhaul is will run somewhere along the lines of € 12-15k.

An SMA 230 would be much to heavy. For the Seneca the problem is that the Seneca uses counterrotation engines. It would be ideal for the SR20, Commander 114, TB20 and the Seneca. ... And offcourse the C182.

For more performant aircraft like the SR22 and SR22t (both 310bhp), the Commander 114TC, etc... the engine is not powerfull enough .. even though you may fly at 100%. I keep praying for a 300bhp engine with below 500lbs weight.

P.S.

yes the diesel engine will be heavier yes Jetfuel is heavier

but...

the fuelburn is a lot less. So you can also take less fuel with you.

2400h TBO is a great start (how did they manage to get this, I rather don't want to know) and they hinted something about 2800h soon and then 3000h later. You can believe these statements like people believed Thielert who "guaranteed" fixed maintenance costs per hour.

Obviously you are right that without an actual track record you don't have a, ahem, track record...

The real question is how much weight people are going to attach to that. One would think that, post-Thielert, the diesel engine business (and Diamond) would be dead. But enough people prefer to "believe" and take the chance.

Have Diamond ever offered a guaranteed cost per hour, like I believe Rolls Royce (etc) do on their jet engines? That could be a great package for FTOs. OTOH Diamond don't need to do that because there is no other option for that market - apart from the Tecnam twin.

So you can also take less fuel with you.

But, presumably, you are still allowed to fill the tanks right up? So you have less cockpit payload. But that means the wings carry more stress, which needs to be certified as OK.