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Showing content with the highest reputation on 04/13/2019 in all areas

  1. 1 point
    CS, maybe not. But in-flight adjustable options are getting better. IVO Prop and Airmaster have been known around here for a while. There are also a lot of props coming out of Ukraine and Russia these days. Their thing is mostly ground-adjustable props for <130hp and they seem to be marketing their products more toward the STOL guys so I haven't paid them much mind, but if you look at this link (http://www.airtrikes.net/propellers.shtml) you can see that one of the companies, calling themselves Kool has an in-flight adjustable option. If you go this way though, it's worth making sure that they understand that you'll be using a direct-drive engine. Apparently they're not as common outside North America and there have been some blade failures over the misunderstanding. Ground adjustable models run about 1200 USD, in flight adjustable models go for 1800. Another option, sure to stir up some controversy, is the Aeromatic propeller. It was a precursor to the modern constant speed propeller and was kind of a thing for a while on certified aircraft in the post-war era. Air pressure against the blades pushes the pitch toward fine, but centrifugal force on a set of counterweights in the hub as the prop speed increases forces the pitch toward coarse, ideally finding an equilibrium. Univair quit making them I think in the 60s, and the propeller went out of style, but a guy named Kent Tarver revived them a few years back. Reviews are mixed to say the least. Some people love them, saying they're the next best thing to a CS prop at half the price, and others say they hate them and would never fly behind one but I can never find much specificity to the haters issue. I have turned up that the prop hubs will leak a little oil, and that in certain flight regimes the prop will seem to "hunt" back and forth rather than settling on a pitch for the RPM it's at. Used ones don't seem to be easy to come by, but no telling if that's good or bad. Tarver used to make claims like "60+ years without a single AD" or something like that (the first ones were built in 1946 and some are still flying apparently), but I haven't seen that in a while and the claim is gone from his website. It also seems he got tired of wrestling with the FAA and gave up on the certified market. I haven't seen any crashes or anything relating to the failure of one of these things, but it also looks like they were never all that popular, so who knows? If you want to see what all the fuss is about a new one will cost you about 5400 USD.
  2. 1 point
    I can understand CS props on airplanes that burn 20-50 gph or cruise above 200 kts but for airplanes burning 8-10 gph or cruise <150 kts I don’t see how the tiny fuel savings or small boost in speed can justify CS.

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