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The Staff of SOH
new jet engine looks broken
- Thread starter Paul Anderson
- Start date
Skyhawk_310R
Charter Member
One of the comments nailed the truth of this. There is absolutely nothing new about this engine. I'm not holding that against you and that was directly claimed in the news article. But, that claim is wrong. This is simply a double fan design un-ducted fan (UDF). The UDF was experimented on many years ago. I recall that McDonnell-Douglas looked at it for their MD-80.
What you are doing is adopting a heavily sloped series of compressor blades hoping to rotate them at a higher RPM without losing airstream efficiency. Ultimately, you have a smaller series of ducted fans inside the nacelle, which then act just like a turbojet. The absence of the ducting reduces weight. But, you also lose a degree of airstream efficiency, which is why the UDT never was adopted. In truth, the nacelle is not that heavy. Further, the UDT is really just an extension of the concept of the turboprop engine. At certain speed ranges, it is more power efficient to run a turboprop. The UDT was an effort to increase that speed efficiency range to speeds currently flown by high-bypass turbofan engines.
Ken
