Originally Posted by alexe
Iím sure you guys did some testing on this prior to deciding to drop the shroud. Is there any benefit/penalty without the shroud?
Yes, some detailed testing was done in conjunction with some other testing that was happening and the data indicated that benefit from the use of the shroud was net neutral.
No negative impact, but no benefit either. Considering the additional cost of using the part, the amount of labor/build time to install it, and the added risk of something going wrong with the disassembly/ reassembly that was involved, the decision to delete it from the design was an easy one.
Because of these factors, I also wouldnít advocate for anyone doing the delete unless they were already disassembling for a 5 year hose replacement or other work.
Having said this, a lot of people may wonder why it was even used in the first place......
Being totally transparent and straight up.....
It was plain and simply a conservative engineering decision out of ignorance and lack of experience with the Rotax 912.
When the RV-12 developement program was started, we were venturing into enough new territory as it was. Reinventing the wheel with the engine installation was not something we were trying to avoid if possible.
We new we would have about as tightly of a cowled engine as there was at the time, and Rotax had a factory cooling shroud available for use on tightly cowl engines. The natural assumption was that Rotax has years of experience with the engine and if they have this part available, it must be needed. Problem was it was hugely expensive, so we designed our own.
It was only after getting a lot of experience with the engine ourself that we discovered it is not always necessary.