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Prospect: Wing extension and Vne

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  • Prospect: Wing extension and Vne

    Cruise, with normal wheels and wheel pants, is within a few knots of Vne. That does not sound like a comfortable way to fly the plane. That makes me wonder about having both the wing extensions and normal tires. Any comments?

  • #2
    Not that close to Vne in cruise, unless youíre near sea level. Vne does become a factor if you descend by pitching down without reducing power. With the extensions your primary descent tool is power reduction, not pitch change.

    If you plan on using the plane as a fast cross-country cruiser most of the time (i.e., normal tires with wheelpants) I would consider not getting the wingtip extensions. I have about 700 hr each in Petersonís 260se/stol (standard wing) and Katmai (extended wing) aircraft and the takeoff/landing performance differences are noticeable to the practiced hand but are not very large at all. I never had a situation where the extended wing or lack thereof was a go/no-go factor, not even close.

    I enjoyed the 4-5 kt low-end margin conferred by the wing extensions but if I were doing a new plane it would be a Kenai, no question, perhaps with an extra set of large tires for backcountry fun.
    Kevin Moore
    Former 260se/stol Katmai with BRS owner; planeless for now
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    • #3
      "Not that close to Vne in cruise, unless you'íre near sea level."

      I understand there is a good margin with tundra tires, but there does not seem to be a lot of margin with small tires. The reason I say the speeds are close is that Katmai Vne is listed as 157 knots. From all I have found out, cruise should be about the same as Kenai when using the same tires. Kenai cruise is listed as 152 knots (LOP) and 156 knots (ROP). Either one sounds uncomfortably close to 157 knots Vne. As to sea level -- I would expect those cruise speeds as long as I can get 75% power. Cruise speed is normally based on performance at 7,500' or 8,500'.

      "I enjoyed the 4-5 kt low-end margin conferred by the wing extensions but if I were doing a new plane it would be a Kenai, no question, perhaps with an extra set of large tires for backcountry fun."

      That's what I am thinking -- a Kenai with Katmai landing gear and an extra set of bush wheels. Hence my questions about how easy it is to switch the wheels as appropriate. I would fly mostly front country (small tires, preferably with wheel pants) but enough back country (big tires) that I'd like to easily set up for it.

      Thanks for your comment about the lack of an extended wing not being a nogo factor -- I wondered how many places are suitable with wing extensions, but not without the extensions.
      Last edited by AirVoyageur; 02-16-2018, 04:14 AM.

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      • #4
        Originally posted by AirVoyageur View Post
        "Not that close to Vne in cruise, unless you'íre near sea level."

        I understand there is a good margin with tundra tires, but there does not seem to be a lot of margin with small tires. The reason I say the speeds are close is that Katmai Vne is listed as 157 knots. From all I have found out, cruise should be about the same as Kenai when using the same tires. Kenai cruise is listed as 152 knots (LOP) and 156 knots (ROP). Either one sounds uncomfortably close to 157 knots Vne. As to sea level -- I would expect those cruise speeds as long as I can get 75% power. Cruise speed is normally based on performance at 7,500' or 8,500'.
        Vne is an indicated airspeed (KIAS) number, while cruise speeds are true airspeed (KTAS). At 7500-8500 feet, 157 knots true airspeed is something like 138 knots indicated airspeed in standard conditions, 19 knots below Vne and within the green airspeed arc (Vno, the beginning of the yellow arc, is 140-142 depending on the 182 year of manufacture). 152 KTAS (LOP) is more like 133-134 KIAS at those altitudes.
        Kevin Moore
        Former 260se/stol Katmai with BRS owner; planeless for now
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        • #5
          Thank you for the reminder on speeds ... I'm suitably embarrassed ...

          Originally posted by kwmoore View Post
          I enjoyed the 4-5 kt low-end margin conferred by the wing extensions but if I were doing a new plane it would be a Kenai, no question, perhaps with an extra set of large tires for backcountry fun.
          Your preference for the Kenai brings up something I have had trouble understanding from the web pages -- what is the difference between a Katmai and a Kenai other than the wing extensions, the stronger landing gear on the Katmai, and the different default tire size? Is there some other reason for your expressed preference for a Kenai?

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          • #6
            Originally posted by AirVoyageur View Post
            Thank you for the reminder on speeds ... I'm suitably embarrassed ...
            Eh, no worries.

            Interestingly, my 260 hp IO-470-powered 260se & Katmai had about the same ROP cruise speed as the Kenai achieves LOP (low 150's KTAS). Somewhat greater fuel consumption in my planes though, 13-14 gph block-to-block ROP. The LOP Kenai will be 1-2 gph less block-to-block as its LOP operation is more efficient. My descent technique from either ROP cruise (as above, about 132-134 KIAS) or LOP cruise (126-129 KIAS), was to pitch down for 140 KIAS (top of the green arc) and adjust power for a 500 fpm descent. In practice this was 18"-19" manifold pressure in smooth air for the IO-470.

            Originally posted by AirVoyageur View Post
            Your preference for the Kenai brings up something I have had trouble understanding from the web pages -- what is the difference between a Katmai and a Kenai other than the wing extensions, the stronger landing gear on the Katmai, and the different default tire size? Is there some other reason for your expressed preference for a Kenai?
            The key distinction is the extended wing. A year or so ago I wrote an article for Cessna Flyer magazine about the evolution of the Kenai & King Katmai that I think explains the differences pretty well; if you'd like a copy feel free to contact me by email at moore dot kw at gmail dot com.

            "Stronger landing gear" (a sturdier nosegear strut; the maingear struts are the same as stock as I understand it) and tundra tires are provided for those who will use the King Katmai mainly for backcountry or rough strip operations, but are in principle optional. My own Katmai had the stock struts, standard tires and reduced-drag wheelpants (see photo)--it was essentially a 260se/stol but with the longer wing.

            I used the planes mostly for travel and day trips from one paved runway to another. Additionally I really enjoyed practicing short takeoffs and landings and often went out to do this just for fun. I was based at KPAO in the SF Bay Area, a sea level airport with a 2443' runway, and often pondered which quarter of the runway I wanted to use. Only a few times--certainly less than 100 hr total--did I try backcountry and unimproved strip flying. Interesting and fun, but it never became my main motivation for flying. Thus my own choice if I were doing another one would be a Kenai.

            Having flown 700+ hours each with the standard and extended wings, in my opinion only a very practiced, proficient and skilled Peterson 182 pilot will be able to exploit the difference in low-end performance productively and consistently. An experienced Peterson pilot in a Kenai will achieve better STOL takeoffs and landings EVERY TIME compared to an average Peterson pilot in a King Katmai.


            Kevin Moore
            Former 260se/stol Katmai with BRS owner; planeless for now
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            • #7
              FWIW: When I said "stronger landing gear" I had in mind the stronger nose gear and also the stainless steel leading edge for the main gear, the stronger and re-routed brake lines, the stronger axles, and the stronger brakes. I did not know whether there was any more than that, but that is already enough to be interesting.

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