DA40NG

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Boatguy54

DA40NG

Postby Boatguy54 » Sat Jan 27, 2018 6:28 am

I'm a student pilot expecting to earn a PPL in July; total newbie.

Without going into any background, I am not fond of the 1940's engine management I see in trainer aircraft in 2018. A glass cockpit mounted behind an engine that looks a lot like a less refined version of my 1960 Porsche does not instill confidence. Just this morning we canceled a training flight when one such engine could not smoothly increase its RPM. I also have extensive experience (5,000+ hours) with both marine and automative diesel engines which I've found to be extremely reliable. Given air and anything approximating clean fuel, they just don't stop. Hence my interest in the 40NG.

At the same time I've read some pretty sharp attacks on the DA40NG, in these forums, and elsewhere. In this forum there should be some 40NG owners, and some 40XLT owners that wouldn't go near a 40NG. I'd like to ask for some perspectives, ideally fact based, on the virtues and faults of the 40NG with respect to the power plant. The canopy and many other aspects of the aircraft are shared between the two variants and a separate discussion.

Thank you for your time and consideration.
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Re: DA40NG

Postby Colin » Sat Jan 27, 2018 9:46 pm

Boatguy54, where are you located?

I have a DA42 and one of the driving factors behind the decision to move up from the DA40 was the engine technology.
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Re: DA40NG

Postby avalys » Sun Jan 28, 2018 4:39 am

I have the good fortune of having a 2007 DA40 XLS and 2016 DA40NG available to rent, for essentially the same price.

The engine in the DA40NG is great. You don't even have to think about it. It's literally like a car engine - turn the key to start, and move the lever for how much power you want. That's about it.

Advantages:
- Water-cooled, so no worrying about "shock cooling" in descent
- No need to manually manage propeller RPM or mixture
- You set power by a percentage: 50% power always has the same fuel burn at any altitude.
- Very efficient and economical - 6.6 gph at 75% cruise, gives about 25 mpg at 150 mph, easily 6 hours endurance.
- Turbocharged - gets faster as you climb, and almost no reduction in climb rate with altitude. An awesome plane for mountain flying and long XC
- Jet-A is a good $1 cheaper than Avgas at most airports, and you'll burn less of it
- Runup is completely automatic - push a button and wait for the computer to tell you it's done

Disadvantages
- Engine and fuel system is heavier and more complicated.
- Likely more expensive to purchase and maintain.
- Certainly, more things to go wrong. Liquid cooled, so you can run out of coolant or have some other problem with that system. There is a propeller gearbox, which can fail/overheat. The fuel can overheat (there is a fuel temp gauge). The engine only draws from the left tank, so there is a transfer pump you must manually activate occasionally during flight to keep the tanks level. The turbo can fail, FADEC can fail, etc.
- Mostly, the weight is the major disadvantage.
- Approach speeds and stall speeds are significantly higher.
- With two 210-lb guys in the front seats, and full long-range tanks, you will be right at max gross / max forward CG.
- Turbocharged engine produces only 160 hp at sea level, vs. the 180 HP DA40.
- Brakes feel undersized given the increased weight of the plane
- Overall, the plane feels heavier and not quite as sweet as the DA40 to fly.

Overall, I like the DA40NG a lot, but it is pretty apparent that they crammed a heavier, more complicated engine into an airframe that was not really designed to carry it. The Austro diesel seems a lot more natural in the DA42, and the newer singles from Diamond (I am drooling over the DA50).

I'd be hard-pressed to decide which one of these two planes to buy. Ignoring acquisition costs, I'd probably give the edge to the NG. And if you fly to the mountains a lot, or live significantly above sea level, the NG is a no brainer. And it's probably a bit more future-proof given the uncertainty surrounding 100LL. But - it's definitely got a severely compromised useful load, and feels heavier and more plodding to fly.

Overall, the engine is cool, but the weight and complexity produces pretty noticeable disadvantages that don't go away once the novelty of "Hey, no mixture lever!" wears off. In practice I don't really find that my workload is any lower with the DA40NG vs. the regular DA40 - once you get the hang of it, it's not really that hard to manage an IO-360.
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Re: DA40NG

Postby Keith M » Sun Jan 28, 2018 9:36 am

Alex has pretty much nailed it. The extra engine weight increases the stall speed by 11%, and the energy to lose on landing increases by the square of that, with no airframe parachute to fall back on if the engine quits. If you can find a DA40 with the Centurion 2.0S engine, it'll give you most of the advantages of the NG, without the extra weight.
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Re: DA40NG

Postby pietromarx » Sun Jan 28, 2018 8:12 pm

I certainly wanted to like the NGs, but in the end bought another IO-360. Everything about the IO-360 is simply less expensive and easier to maintain. Yes, it is 1940s (probably 1930s) technology, but...

1. Every A&P in the world knows how to deal with it, as well as every pilot, builder, etc. I've been stuck way out in the middle of nowhere and never had a problem finding someone within minutes who could help. Annuals are easy to arrange and inexpensive.

2. The parts are well-stocked, standard, and well known.

3. The management is really quite simple. One extra lever and a 90-second run-up. After decades of flying it really becomes second-nature to adjust mixture for altitude, etc.

4. Managing the prop is really a question of noise and speed/efficiency. I personally like being able to lower the noise and take my time when I want to.

5. The fuel issue is the biggest one to me. I personally hate the idea of dropping lead into the atmosphere. Further, at some point there will be no more 100LL. That said, I'll probably not be flying then and there will be modifications available for the engine, fuel system, and airplane. I don't view it as being much more than some unforeseeable expense down the road a bit.

6. I live in California with mountains, deserts, and high temperatures. There has never been a time when I've had an issue with getting to altitude. There are mountains and airports which the DA-40 simply should not try and deal with, regardless of the engine.

Just my $0.02.



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Re: DA40NG

Postby Boatguy54 » Sun Jan 28, 2018 9:01 pm

Colin - I'm in the San Francisco area.

Others - Thank you for the comments and I invite others as well.
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Re: DA40NG

Postby Rich » Sun Jan 28, 2018 9:36 pm

And I would point to two accidents, one each in 2016 and 2017 instigated by power loss, and yet another incident of power loss in 2017 in which the pilot landed without damage - so it doesn't show up in the NTSB database. All 3 were NG's and all happened in Arizona. Whether due to an inherent fault of the engine, a maintenance issue or pilot mismanagement it raises the question of how foolproof the Austro engine in a DA40 really is.
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Re: DA40NG

Postby H60 pilot » Sun Jan 28, 2018 11:38 pm

I have no experience personally flying the NG, but as a potential buyer for either of these models I've spent a good deal of time studying Diamond's literature on them. I find DAI's comparison of them skewed and intentionally misleading, example: Diamond hasn't updated the performance numbers for the XLS or XLT in the POH or sales brochures, in fact, with the new website Diamond retrograded the XLT's performance numbers to reflect pre-XLS figures. I'll let owners who know first hand the advantages of the Power Flow exhaust share their comments, but everything I've heard/read suggests it's noteworthy.
But assume the PF exhaust provided no benefit at all, the 40NG comparisons remain skewed. While the two engines may produce the same horsepower at 3,000 ft, the IO-360 powered model still maintains a greater power-to-weight ratio (think take-off and climb performance) up to 5,000 ft. I emphasize that this remains true even if the PF exhaust yielded no benefit whatsoever.
And what about cruise performance? Remember that DAI-C used to advertise the XLS as a 150 kt cruiser on 10 gph. Today they not-so-ironically claim the NG will plod along at this speed . . . at an astounding FL160! That is 154 kts at a non-breathable, supplemental oxygen altitude, mind you from an airframe that doesn't even come optioned with this required equipment. Max range, endurance, and economy cruise are all equally given at nosebleed altitudes, FL140 and higher. Interestingly, when corrected for altitude, the NG is 5 kts slower at 6,000 ft than the XLT with DAI-C's published numbers. Again, evidence I believe of Diamond's intentional sales effort to upsell NG powered 40s.
From my perspective, the final nail in the NG coffin is the Lycoming's IO-360 management; it's stupid simple. We're not talking about a TSIO-550 here, to date there have been zero, nada, nill, DA40-180 engine related events reported to the NTSB. I needn't mention the Austro's accident history, that it exists at all given the model's recent certification is telling.
Last edited by H60 pilot on Mon Jan 29, 2018 1:32 am, edited 2 times in total.
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Re: DA40NG

Postby Rich » Mon Jan 29, 2018 12:03 am

As far as PF goes, if the IO-360 as delivered in the original version is 180 HP then the PF version is effectively about 205 HP. Improved climb way above and significantly better cruise numbers over what I had before I converted to PF support this. Before PF I matched book figures. (Mine is the old, slow 2002 version.) Since PF I easily beat book figures all the time. Improvement in higher altitude cruise is more than lower elevations, interestingly.

And given that my old 40-gallon bird is one of the lightest around and has the MTOW/MLW conversion, the overall utility for my missions is far better than the NG.
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Re: DA40NG

Postby Lance Murray » Mon Jan 29, 2018 2:21 am

I might believe the PF adds a couple hp but 25? Does your increased fuel flow and higher CHT support this?

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