DA40drvr wrote:
My experience of flying a PA28-181 [the aircraft I trained on and flew for many hours before I got a DA40] was that it did not achieve even these figures – typically 3-4 kts slower.
Remember that an air speed indicator has a 5 Kts tolerance at those speeds. So comparing two aircraft there could be at 10 Kts difference, while still within tolerance.
I am not sure that I agree with the statement about lack of aerodynamic efficiency, compared with older aircraft with a similar engine.
The book figures for a PA28-181 (with the same O360AM engine – admittedly not fuel injected like the DA4) are 125 ktas at 10.5 usg/hr.
My experience of flying a PA28-181 [the aircraft I trained on and flew for many hours before I got a DA40] was that it did not achieve even these figures – typically 3-4 kts slower.
I achieve 141 ktas at 8,000ft on 8.0 usg/hr in my DA40, 133 ktas on 8.9 usg/hr low down
Taking the ‘enthusiastic’ book figures for the PA28-181: low down, the DA40 is 6% faster with 15% less fuel burn; high up 13% faster with 24% less fuel burn.
Some of this may come from the DA40 Powerflow exhaust, better prop etc. but I would find it surprising if there no gains from aerodynamic efficiency (even from the smoother composite wings and surfaces)
Michael wrote:
I just can’t get my head around the fact that whilst the DA40 is all composite and a 21 Century design, it has zero aerodynamic advantage.
Well, when you say Diamond, aerodynamic wizards isn’t what springs to my mind. 
And the fixed gear isn’t an improvement.
I quite like the DA40. But nothing is perfect. I don’t care for the take-off performance of the NG. Given the control layout, I would prefer to fly it from the right seat for which the instrument layout isn’t really suitable. And I wouldn’t mind a parachute. It generally isn’t a strong argument for me, but the DA40 is a good sightseeing plane and when sightseeing, you’re often low and slow, sometimes with an increased risk of collision (especially with birds) or over hostile terrain. You can always try wearing one. 
An MT propeller is maintained on condition under FAA Part 91. MT recommends an overhaul every six calendar years in service but they have no authority to require it. Obviously MT makes a conservative recommendation, because in doing so they write their own paycheck.
I overhauled my MT prop after 14 years, but at only a few hundred hours TIS under prior ownership. I was concerned about the grease condition. The overhaul shop found nothing that needed attention, but while they were in there they updated the hub to incorporate the latest seals, which now prevent the previously typical MT grease leaks.
AnthonyQ wrote:
I note that it is N reg….presumably operated under Part 91…Was there a good reason for the six year prop overhaul? Or is it s life-limited part on a DA40?
Yes, Part 91. As I understood it was required by MT on the propeller (irrespective of N-reg).
There are advantages to the DA40 compared to a 20-year old plane; safety features, G1000, GFC700, TCAS, TAWS, airbags, 26G crash cell, accurate fuel guages …
Interesting comments about the DA40 versus 177 RG, I had never thought to compare the two. The Cardinal is a lot better looking and huge inside.
I fly around in a Lycoming powered DA40 regularly acting as safety pilot for a friend who needs IFR approaches. It’s a nice planeand really the only issue I’d have with it is front seat room. I’ve now figured out how to get comfortable using a cushion behind my back to recline more in the seat, adding head room. With that, I have just enough head room and just enough knee room.
Michael
I think the DA40 has considerable advantages over the older aircraft but these are mitigated by the need to make the composite structure robust enough to survive in the GA environment.
The composite structure could be made much lighter to meet the structural requirement of flight, the problem with this is that some parts of the aircraft would become very lightly built and likely to be broken by careless handling, this would result in damage happening on an unacceptably regular basis.
The German/ Austrian approach is quite good as they have considerable composite experience with gliders, the Cirrus approach is more conservative and having viewed the Cirrus structure IMO if this aircraft had been built by one of the leading European manufacturers it would have been 100Lb lighter.
Peter wrote:
But many people like a nice modern plane, for all sorts of reasons including looks.
True, if you want a G1000 you need to buy a post 2005 circa plane.
I just can’t get my head around the fact that whilst the DA40 is all composite and a 21 Century design, it has zero aerodynamic advantage.
AnthonyQ wrote:
Btw it does have the same IO360 200 HP as the Mooney M20J vs 180 HP so would expect it to lift more…
The difference is just the higher compression ratio so the angle-valve, hi comp IO-360 is more efficient than the same displacement, straight valve – low comp 180Hp version on the DA40 and Cessna 172S.
