Just watched a 1989 news clip touting the promise of the Ultra High Bypass (UHB) Propfan, or Unducted Fan engine (UDF). I'm not an expert, so I was wondering: What became of this technology? It doesn't appear on many aircraft I've seen. Am I just out of the loop?

>Just watched a 1989 news clip touting the promise of the>Ultra High Bypass (UHB) Propfan, or Unducted Fan engine (UDF).> I'm not an expert, so I was wondering: What became of this>technology? It doesn't appear on many aircraft I've seen. Am>I just out of the loop?Seems like the Russians were at the forefront of that technology, but no one else was using it. I think the Russians have an experimental aircraft that uses it. A C-130 size transport plane if I recall. Anyway, I think with the Russian plane, the only drawback has been lack of $$$$ to fully devlop it...not surprising with a Russian project. The Russians are always good with new air designs. It's just that these days, they often don't have the financial resources to follow through on them. Look at the Berkut project, for example. It's too bad.Also, isn't the unducted fan jet very similar technology to the engines that are on the newest C-130's? You know the ones with the 7-blade fan props, or whatever it is?RhettAMD 3700+, eVGA 7800GT 256, ASUS A8N-E, PC Power 510 SLI, 2 GB Corsair XMS 3-3-3-8, etc. etc.

Because they lost efficiency when they started getting closer to jet cruising speeds. Also the drop in oil prices made the airlines go to hi bypass fans instead because of their speed. There are a lot more reasons but I know that was one of the largest problems.

Hi CF,I just happened to be at Yuma when they did the test several years ago. I think it was a DC-9. I believe two things killed the project, one was the NOISE the darn thing made. And the other, was no way to contain the blades in case of a bird strike. The FAA is big on blade containment.Regards,Bob I..... in sunny Florida

thanks guys. was curoius. i can see the point about bird strikes!

>I just happened to be at Yuma when they did the test several>years ago. I think it was a DC-9. I believe two things killed>the project, one was the NOISE the darn thing made. And the>other, was no way to contain the blades in case of a bird>strike. The FAA is big on blade containment.and as the AA 767 explosion in LAX showed. it doesn't matter how much kevlar is shielding them, if its spinning at 10,000+rpm and it massively fails, it ain't being contained.i also think a delta md88 engine failure killed a pax with a blade going through the cabin if i am not mistaken.i still don't understand why blade containment would kill this either? if that is the case, shouldn't every 121 turboprop be grounded?

That seems kinda odd with all the turbo props. They all work off the same prinicple with a jet powering fan blades.

I believe noise was a significant issue as well... You may have seen that NASA small GA concept that incorporates a ducted fan on a reciprocating engine. This was done in an effort to further reduce noise. Danny