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News from Wednesday, 7/12/2005

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Thielert conversion for the PA46, Yes or No?
by Wilhelm Schröer

Dear Malibu-Mirage friends,

It is a somewhat heated discussion and thoroughly emotional: Thielert conversion for the PA46 –yes or no?

Would it be technically possible? If so, would it make economic sense? Would there be a market for such a project?

We have been discussing this question in the committee since the end of 2000 –regularly there have been new initiatives and updates –and recently at the Straubing brunch we were able to have detailed discussions with representatives of Thielert, Rieger and Mühlbauer. In the meantime we have received insider information to the effect that JetProp is looking into the feasibility of the project and has even visited the Thielert factory. The momentary situation is as follows: Thielert themselves will NOT support a PA46 project financially, though they will supply engines and development services against payment.

The principle is here quite clear: Thielert is a supplier of engines and regards itself as market leader, due to the lack of competition. If you want to be supplied by Thielert, you have to pay in full. They don’t see the need for investing money up front.

Rieger and Mühlbauer HAVE looked at the financial question: A simple feasibility study which would deal with the necessary questions like effect on performance, construction changes etc. would cost around EUR 50,000. This sum would have to be invested before the project could start. Currently no-one is prepared to invest this money free of charge. Once feasibility has been established, a complete STC procedure would cost some EUR 500,000 providing that a plane is made available for about a year for the initial conversion. The total costs for a Thielert conversion together with the costs for the engine, cooling system, propeller and spare parts etc. would amount to some EUR 150,000 –200,000, IF it works and isn’t too heavy.

However, we don’t have the facts. While the 310 HP Thielert Engine has already completed a number of rounds in the Duke, we are still waiting for the 350 HP engine. In both cases practical experience is effectively zero.

There are still questions to be answered concerning the various cooling systems, of which there are no fewer than eight. And there are unanswered questions concerning the incorporation of the compressors for the pressure cabin and the air-conditioning.

Thielert’s basic engine weighs approx. 275 kg (a comparable Continental weighs in at approx. 220 kg), but JetProp is working on the assumption that a fully configured Thielert engine will in the end weigh in between 350 and 400 kg –which is absolutely out of the the question. According to the JetProp calculations this would mean going without the entire storage room.

On top of all this there are the unresolved issues of performance at higher altitudes, re-ignition at higher altitudes and the heat resistance of the engine.

We have heard from reliable sources that there were considerable problems with the cooling system in the Duke project, besides the generally poor performance. On account of the high revs, this topic has already become a permanent concern with the turbo-diesels.

We have now agreed to carefully follow the progress of the Duke project and wait and see what happens there.

The committee recommends not paying twice to learn the same lessons. As far as we can tell there are too many problems for a Malibu conversion. In particular, the question of weight appears to be critical.

We plan to give you more information during next year’s fly-in. In the meantime we would be grateful for any contributions on this topic and would like to hear your views, which you can air on our Forum.



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