I think there are a variety of the reasons why the DA50 may not be a successful airplane, but I do want to call out a couple of your assertions.lgrennlee wrote: ↑Thu Nov 18, 2021 3:02 am Also the tanks rely on a transfer pump which can be left on and auto transfer but if forgotten the transfer rate is "only" 60G/hr. It's possible that one might not be able to put all of the fuel in the main tank before it runs dry if they forget. Also the pump could fail creating a fuel emergency very quickly.
Along those lines... and this is potentially important for a high performance aircraft. The Cirrus Vno is 176 KIAS, The DA40 is 152 KIAS. That is a pretty low value when I'm sure the plane is quite slippery. It will prevent "high performance" descents when it is bumpy out. It may also limit top speed when a bit lower to the ground.
Most single engine aircraft require some fuel tank management. The DA40 and SRxx both require switching between R and L tanks at the appropriate times. My DA40NG requires the same fuel transfer from R to L as the DA50 and it's never been an issue. In the event of transfer pump failure, the engine becomes the transfer pump since it returns about 90% of the fuel pumped from the L tank to the L tank. Switching the fuel selector to the "Emergency" position causes the engine to draw from the R tank and then the engine will transfer fuel from the R tank to the L tank at about the same rate as the fuel transfer pump.
The DA40NG Vno is 130KIAS which you may have confused with the Vne which is 152KIAS in the NG and 178KIAS in the DA40 Lycoming. Perhaps your reference to 152KIAS is for the DA50? Or is there confusion between Vno and Vne?
The DA50 is much larger and more comfortable than a DA40 or SR22, but it is definitely lacking in range and speed to compete with the SR22.
Diamond is all about engineering, marketing and customers are an after thought at best. Cirrus is all about marketing and customers with very little innovative core engineering in the SR series (though the Vision Jet is clearly an engineering accomplishment). The introduction of the DA50 continues to underscore this difference between the two companies. You asked the right question which Diamond did not; who is the customer for this airplane?