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Diamond DA50

I think any time you build a completely new engine, there are issues. It’s certainly true that the original Thielert concept has come a long way since the Christmas party bet between Frank Thielert and Christian Dries that resulted in a hurried, basically non-engineered initial design. A lot of money was spent after that, but not all the lessons will apply to a new larger engine designed by a different staff, witness the Rotax V6 debacle. The guy who led the Thielert design initially now works elsewhere and people matter: design utilizes technology, it is not itself completely a product of applying technology.

Re sandwich construction, minimum skin thickness to take small aircraft wing skin line loads etc: any reasonable composite structure uses honeycomb or foam cores when necessary, sailplanes of the 1960s sometimes used balsa, even my friends Wittman Tailwind has a feather light CF cowling that utilizes honeycomb cores under skins so thin you can almost see through them. It’s reasonably robust to handle. This is an advantage of composites – you can’t so easily reduce skin thickness with manufacturable metal structures while keeping them robust enough for ground handling, for example the wing leading edge skins on my ex-Luscombe were 0.016 inches thick and easily dented.

On the other hand, composite aircraft structures are sometimes heavy due to design certification standards that reflect the lack of available fatigue data. This requires load path redundancy and low design stresses in primarily structure, in a situation that does not generally apply to certified metal structures.

With the above issues in mind, it is noteworthy to me that some manufacturers tend to use metal for primarily structure and composites for secondary structure, but the technical situation is specific to a particular design.

Last Edited by Silvaire at 27 Jun 15:18

arj1 wrote:

1. No chute? Yes, I know that complete engine failures for diesel engines we reportedly 10+ times less likely, but still?

Since when did Diamond listen to the market? They could have DOUBLED their sales of the DA40-180 if they would have listened to what has bean beaten to death on the Diamond Aviators Network. It takes them YEARS just to provide a listening ear to the complaints of owners confronted with obsolete G1000 systems…

1.
2. How did they manage to achieve empty weight to MTOW ratio of more than 70%?! I mean, wow! Yes, engine is heavy, but not three times more heavy.

They take the easy route, accept unacceptable compromises and if it leads to an unsuccessful product they go “oops” and come up with a “dash VI” version sometime down the road. Look at the DA42. Look at the killer design of the DA40 NG’s instrument panel. Lack of oversight on engineering?

Can it be done right? Well at least much much better: look at Pipistrel. The Panthera’s actual empty weight puts an end to the debate about whether composites can be made lighter and stronger than metal in certified aircraft. Yes they can.

1.
3. As @Peter has mentioned below, why FL200 max and not FL250? Even with previous engine models Diamond has achieved FL350 during testing…

Hmm, I am not with you on this one. The step from FL200 to 250 entails a number of technical and operational challenges. Probably the low critical altitude of the engine (8000 ft) is a factor. But from physiological point of view, I really think anything above FL180 should be pressurised.

All in all I am scratching my head. They may have a market with DA40 owners who need more room, but will they pay (guessing) 800’000- 1’000’000 Euros for such a minor upgrade? And run the risk of buying an unproven engine form THE unproven engine company that just recently settled the DA42 TDI debacle?

Diamond lost me a long time ago. But I still credit them for making the DA40 and the DA62, both of which have been very successful.
( I have owned two DA40 and loved every minute of the 1’000 hours).

LSGG, LFEY, Switzerland

And run the risk of buying an unproven engine form THE unproven engine company that just recently settled the DA42 TDI debacle

I didn’t know TCM was involved in the engine program of the DA42. And I’m quite happy with my continental TSIO360 easily going past TBO. I wouldn’t call them an unproven engine company.

EBST, Belgium

Probably the low critical altitude of the engine (8000 ft) is a factor

Does this mean that the turbo runs out at 8000ft and beyond that the MP starts to drop as you climb?

That is very low. Most GA turbo installations are around 15000ft.

Administrator
Shoreham EGKA, United Kingdom

Flyingfish wrote:

Hmm, I am not with you on this one. The step from FL200 to 250 entails a number of technical and operational challenges. Probably the low critical altitude of the engine (8000 ft) is a factor. But from physiological point of view, I really think anything above FL180 should be pressurised.

I thought it is from above the FL250 that aircraft becomes “high-performance” in EASA land and the pressurisation is mandatory…
But my point is that it is for the pilot to decide if he wants to switch from cannulas to a mask twice a year when the weather situation mandates it. Or if the only way to get reasonable shortcuts is to enter upper airspace FL245 and above. And my other point is also that they have tested it at FL350…

EGTR

If it gets to FL350 (pressure c. 15% of MSL) it must have a turbo like a RR Merlin

FL250 is very useful compared to FL200 because it gets you above a lot of warm front wx.

Anyway, a missed opportunity to have 50 USG fuel at 1999kg MTOW. They cannot even charge a hefty amount for “extended tanks” because almost nobody (in this market segment) will pay the Eurocontrol route charges.

Administrator
Shoreham EGKA, United Kingdom

In the US (as a friendly reminder to Diamond – the biggest GA market in the world), you need the high altitude endorsement above 25.000ft. This is why planes like the P210 are certified to that or (model dependent) just below that. Heck, even our old NA C182 has a book service ceiling of 17.700 ft and according to club lore has actually flown up there. Reminder: in the US Class A starts at 18.000 ft.

I’m not a Diamond basher at all, in fact I’ve just been instrumental in buying a DA40 for our club, but this DA50 package is so completely unattractive that I really have to ask: ‘what were they thinking’.

Last Edited by 172driver at 28 Jun 18:59

Honestly, if they ever made a 200kts pressurised diesel twin with long range, I’d be very interested.

A pressurized 6 seat twin fadec diesel would be a game changer.

Freelance IRI / CB-IR Instructor
LOWG | Worldwide

Would it? Surely such a plane would be over 2,000kg and therefore few would buy one due to enroute charges. Once you go there then a SET makes more sense.

S57
EGBJ, United Kingdom
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