DA40 NG (2011) at MCT 92%:
Fuel flow for the DA 40 NG diesel at 9000 ft cruise appears to about be same as a leaned out IO-360 Lycoming – 8.2 GPH. Is this a result of a relatively high percentage power setting on the Diesel? I’m not famIliar enough with the type to know what 150 Kt TAS indicates in terms of power setting.
That is max continuous power (92%).
Somebody reduced power as much as possible and made it from canada to the azores apparently (edit: googled it but can’t find it anymore. It was a very long flight, perhaps even east coast to europe, iirc).
Thanks for that info. It is certainly true that running an engine at high power settings is the way to improve effective power density.
The DA 42 I sometimes fly has an approximate 150kts TAS at 9000ft on 10 gals total per hour ie 38litres. JET A or Diesel at 70% power.
The PA 44, seminole I used to fly had 2 x O 360 Lycomings and cruised at about the same TAS at the same altitude on 72 litres per hour (average) of AVGAS at 2300 rpm and 23 " LOP.
The bigger difference is that at the moment Jet A or diesel are approximately €1.3 per litre whereas Avgas is just over €2 per litre.
In the UK Jet A is about 40% cheaper than it is in France, and if you go to the Channel Islands it is cheaper still.
That’s what’s in the POH, yes.
Snoopy wrote:
That’s what’s in the POH, yes.
It looks like a cheapest certified IFR aircraft per nm!
The M20J at 8000ft does 145TAS at 6GPH, that is 0.15L/nm but I fly it WOT/2500rpm at 165TAS at 10GPH (the POH is is 175TAS)
Acrually flying it LOP at 125IAS all the way climb/cruise/descent does the job for fuel efficiency 
