Peter wrote:
Diesel has less energy than avgas so you need more of it, too.
It’s the other way around. Diesel/Jet fuel has more energy per litre than AVGAS.
On the other hand the density of Diesel/Jet fuel is also higher so the energy density per unit of mass is almost the same.
I feel like they wasted a few chances with this design. Why no turboprop? A downrated 500 hp turbine would’ve fit in well with the airframe, wouldn’t it?
I think it’s great that they used the 2/3 seat layout that is standard for cars for ages, but from the useful load you won’t have many opportunities to fit five actual people in there. The 1999kg MTOW seems very arbitrary, probably to avoid IFR route charges, but I feel like this restricts the capabilities of a possibly more capable airframe.
EASA should really increase that 2t limit, it is holding back aircraft development in my eyes. Look at how cars got considerably heavier over the years due to improved crashworthiness and additional comfort features. The same should have happened with GA aircraft.
Peter wrote:
I don’t think a diesel plane will ever succeed in the US
It seems they’re doing good with DA62 in the US.
I think the twin is a different “formula”. It also sidesteps engine reliability concerns which still linger on over there from the Thielert debacle.
A diesel version of an SR22, made by say Diamond, would not succeed there because it is diesel – because 100LL is cheap and is everywhere. And without a chute it would not succeed anyway; that is now a key component in “spouse acceptance”.
The 1999kg is indeed artificial and wholly due to Eurocontrol-run IFR route charges. However, many airports have a steep hike in landing fees at these round numbers. Those who go above 2T have to get used to recalibrating their expectations, to use that wonderful estate agent / property bear market phrase 
The airframe would probably take more fuel – but of course they are trying to limbo dance under the 1999kg mtow – mooney, bonanza, socata shoved fuel in every corner they could find because they were not working around this aribrary limit of 1999 -
50 Gallons is what the DA62 carries in it’s main wing tanks, it also has an additional 36 Gallons in the auxiliary tanks that sit behind the engines.
The DA50 shares a lot with the DA62 and I think they have used the exact same wing tanks. I really hope they add auxiliary tanks as an option.
That range is ridiculous. I also don’t see it would benefit from a turbine unless you also add pressurization. I really think they’re missing a trick – they should have made a nice 4-seat pressurized diesel long range tourer with a chute. If they did that, they’d own that market and beat Cirrus.
If you read the early prototype flight tests way back I think somewhere between 2004 amd 2008 the early DA 50 did plan for pressurisation. I wonder what happened to make them change their minds along with dropping avgas and the chute.
Diamond also announced turbine in DA50 few years ago.
