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Diamond DA50 Turboprop

Alexis,

I think Rolls Royce builds great Jet engines, and you really cannot take a couple of isolated isolated incidents and critisize a company like that.

RR are top of the edge, technologically further than most competitors, more efficient and also run much quieter. That is also why they NEED to conform to production standards that exceed what other less high strung engines can do. In these two cases, it was demonstrated quite brutally that this kind of thing can bite severely.

This thing did hit home twice in fact. I am pretty close to some folk at EDW, have flown on the same airplane quite a couple of times and some people very close to me much more. When we got to see the pictures of the damage and I got to talk to some people directly involved, it became clear just how close the whole thing had been. First, the explosion ripped through a bunch of cables and damaged fuel tanks and main spar, secondly, when they took apart the 2nd engine, I understand that some people at Rolls Royce themselves got really pale. In fact, the 2nd engine had been damaged sufficiently that the very same thing could have happened to it any moment. Fortunately, it did not. Clogged oil feed due to a non suitable oil used caused an oil fire and destruction of that engine and near destruction of the 2nd one. The repair took several weeks…

And then I remember the morning of November 8, 2010, a up to that pint boring night shift. Then the news came that a A380 had “crashed” near Singapore, shortly later corrected to “has had a major explosion and is currently flying south of Singapore, expecting an emergency landing.” Shortly after they landed, at 0345 UTC, I saw one of the first pictures of the wing damage and simply was floored. Same pictures, much more damage (as it turned out) and much more problems for the crew. I was talking to one of my friends in the field at the time, very senior air safety guy, and told him there and then that I felt that probably the disk had burst and immediately made the connection with the EDW accident.

As it turns out, it was indeed oil related, if a different situation in the way that a feed pipe malfunctioned. The result however was identical, total mechanical and uncontained failure. Enough for me to quote Victor Melgrew and forward some pics to one of the crew of that 330… you can imagine the rest. Much later I also had an exchange with the Commander of QF32 on that and I think it did get his attention… If you have not, I strongly recommend you to read Richard de Crespigny’s book about the accident. That airplane made it on literally one intact wing and one very damaged one, with ONE fully responsive engine and 2 in much degraded function. It took over a year to repair.

It appears that RR have gotten their act together very dramatically after this. It does appear however that they did not pay enough attention after the Trent 700 accident to prevent the Trent 900 failing in a very similar manner later. During the same time, they also had a total destruction of a Trent 1000 on the test stand.

No, I do not criticize RR, but it has to be pointed out that this kind of cutting edge technology comes with risks. Particularly if the result of a catastrophic loss of oil pressure results in parts flying through fuel tanks and cable wires.

Now compare this kind of technology to the enigne in question here. That is like comparing a Volkswagen Bug engine to a Formula one motor. And that is why your engineer is quite right pointing out just how extremely careful they have to be, while there are enough turbines which will react very differently to a condition like that. Russian engines operate at much higher tolerances, but as a result are much less efficient. There is no free lunch….

Last Edited by Mooney_Driver at 20 Jan 19:14
LSZH(work) LSZF (GA base), Switzerland

Besides Materials and precision, the turbo engine (no matter if turbojet or turboprop) needs a considerable higher amount of engineering than a piston engine. Especially if the company is looking to improve the core process, it takes a lot of engineering to put the thermodynamics, aerodynamics, materials and mechanics together. There is a reason, why companies – even the big players – tend not to touch their core processes whenever possible and new developments are mostly tackled by a joint venture of several high profile companies in the field. And Turboprops tend to get trickier, the smaller they get. At least, if you want to archive a least acceptable efficiency. Compared to that, you can build an acceptable piston engine in your garage – as has been done in the past years several times.

Last Edited by mh at 20 Jan 21:25
mh
Aufwind GmbH
EKPB, Germany

There is a reason, why companies – even the big players – tend not to touch their core processes whenever possible and new developments are mostly tackled by a joint venture of several high profile companies in the field.

Or sometimes they don’t tackle them internally at all.

Agilis Website

Besides Materials and precision, the turbo engine (no matter if turbojet or turboprop) needs a considerable higher amount of engineering than a piston engine. Especially if the company is looking to improve the core process, it takes a lot of engineering to put the thermodynamics, aerodynamics, materials and mechanics together

Now is this really true. Lots of people are building jet engines in their garage as well. The cost, the engineering, the complexity is more a result of the business in which the product can enter in a meaningful and profitable way. Jet engines are technology driven because the customers wants it, not because it is needed to make an operational engine. A working and operational jet engine is not rocket science anymore. The customers are willing to pay lots and lots to get the level of sophistication they want or need. No one is interested in a low tech jet, because a low tech jet offers no benefits that can be utilized profitably. The exception is RC jets, fully operational engines that anyone can afford, and also build from scratch with garage equipment. These engines can easily be scaled up, but will be so inefficient/heavy/unreliable that all the benefits are gone. You see a similar effect in F1 car engines also, engines that are light years ahead of any modern ordinary engine. Only no one outside the F1 industry has any use for this level of sophistication, so they remain a circus attraction. Nevertheless, the sophistication of F1 engines are way up there with newest jets.

The elephant is the circulation
ENVA ENOP ENMO, Norway

Other than that it really doesn’t make much sense to fly a turbine in FL100

Why not?

- A turbine has a very high air throughput, so it needs more fuel in dense air to get the stoichiometric ratio in denser lower levels.This makes the turbine a real gas guzzler. The overall efficiency is much lower than a piston engine, this is caused by thermodynamics and will not change much.
- The drag/power ratio goes down the higher you climb. You have more power for forward speed available in higher levels as drag is reduced.

United Kingdom

A turbine has a very high air throughput, so it needs more fuel in dense air to get the stoichiometric ratio in denser lower levels

That’s exactly the same for a piston engine. TB20:

At sea level, 12 USG/hr for 140TAS.
At FL160, 8.5 USG/hr for 140TAS.

Both peak EGT.

Are turbines really worse than the above, or is it that they merely show up the contrast more – because the enroute sector is normally flown so high up?

Anyway, it still remains the operator’s choice. People don’t seem to mind turbines in helicopters and most of those fly at 500ft

Administrator
Shoreham EGKA, United Kingdom

Anyway, it still remains the operator’s choice. People don’t seem to mind turbines in helicopters and most of those fly at 500ft

But then again people also don’t seem to mind to pay 1000$ or so for a basic turbine helicopter per hour…

It’s just that the SHP needed for a say 1 ton helicopter would require a big and heavy piston engine, so the turbine can play its weight advantage. Also, endurance doesn’t seem to play such a big role, as helicopter legs are often only a quarter of an hour or so.

LSZK, Switzerland

More details here

Administrator
Shoreham EGKA, United Kingdom

So no more turbine start up sequence videos on youtube with this thing….

I somehow didn’t expect that this DA50 will go into production when I saw the pictures for the first time. But then again Diamond has ma few projects which are still not around, like the conventional DA50, Diamond Jet, DA52…..

EDAV, Germany

Motor Sich is kind of in the middle of the separatist war area… something to keep in mind.

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