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Many small planes have fixed gears, some have retractable gears. All things being equal, the plane with retractable gears would have to be more expensive than fixed gears, as the mechanisms involved in retracting them is obviously more complicated than fixed gears. On the other hand, planes with fixed gears should have somewhat more drag than a similar plane with retractable gears when they're retracted. This would imply that a plane with retractable gears would consume less fuel than one with fixed gears. If the difference could be quantified, how much more economical would the plane with retractable gears be vs. one with fixed gears?

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    $\begingroup$ I guess you meant to write "planes with fixed gears should have somewhat more drag than a similar plane with retractable gears" $\endgroup$ – Peter Kämpf Apr 12 '18 at 19:54
  • $\begingroup$ The difference is quantifiable. Look at the difference between the Cardinal 177's with fixed gear vs the retractable ones. Or the 172 RG's vs conventional. $\endgroup$ – Ron Beyer Apr 13 '18 at 0:49
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    $\begingroup$ It is pretty common for retractable gear to allow an aircraft to fly faster, on the same engine, instead of to fly at the same speed, with lower fuel burn (although there is always a choice of what throttle setting to use) Additionally, realize that retractable gear generally adds weight to an aircraft as well, which further complicates things. $\endgroup$ – Adam Apr 13 '18 at 1:40
  • $\begingroup$ Cardinal's with fixed gear (FG) can supposedly be almost as fast as retractable gear (RG) when equipped with good aerodynamic fairings. I'm changing mine now - better nose wheel pant with fairing to clean up the nosewheel scissor; better main gear wheel pants with a more aerodynamic fairing over the leg and the top and bottom of the leg fairing; a better tailcone fairing to close gaps around the stabilator trim tab rod; and a fairing around the exhaust pipe. Once the paper all settles, we'll see how it does! RGs also have 20HP more to haul their extra gear retraction stuff. $\endgroup$ – CrossRoads Apr 13 '18 at 3:28
  • $\begingroup$ @PeterKämpf, yes, that is what I meant to type. Unfortunately, fingers and brain couldn't get it together, and I didn't catch it before submitting. Thanks to fooot for correcting that. $\endgroup$ – BillDOe Apr 13 '18 at 20:50
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Consider the Piper Turbo Arrow IV vs. the Piper Turbo Dakota... Same max gross weight, same engine, same wing, but the Arrow (with retractable gear) is nearly 12% faster at full cruise power. This would imply that, at the Dakota's cruise speed, the Arrow should burn roughly 14% less fuel (give or take a little; it's 75% vs. 65% power, but at different altitudes). Given this, the Arrow will cost less to fly for a given trip ($/nm). The trade-off is that the Arrow costs more to buy, maintain, and insure, while having a smaller useful load.

Note that I chose these models for a reason: The Turbo Dakota is literally a fixed-gear version of the Turbo Arrow IV with no other major changes. In most cases where a model is available in both fixed and retract, the retract has a more powerful engine. This makes comparisons much more difficult. YMMV

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    $\begingroup$ Fuel costs are one thing, don’t forget maintenance costs as well. $\endgroup$ – RoboKaren Apr 13 '18 at 16:36
  • $\begingroup$ @RoboKaren lemme just edit to make that clear... Thanks! $\endgroup$ – ioctlLR Apr 13 '18 at 16:52
  • $\begingroup$ Just to make sure I'm covering everything, I'm only counting fuel, oil, TBO items, and a minor set-aside in the cost per mile. The remaining costs (insurance, parking, annual, repairs, etc.) are important, but without knowing how many hours / miles to spread them over, I don't really include them in the hourly/per mile costs. The Arrow is still cheaper per mile (because it is enough faster), but probably will cost more overall. $\endgroup$ – ioctlLR Apr 13 '18 at 17:07
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One thing to consider is your drag profile and mission requirements. If you have a cumbersome aircraft with high amounts of drag cruising at slower speeds vs. an aircraft designed for impressive maneuverability and high speed, the impact of adding a fixed gear becomes much more drastic. For the cumbersome craft, going with a fixed gear might be much more economical because the complexity and cost is so much less and the added drag of having a fixed gear might not noticeably affect the design parameters. For the other example, the added drag of having a fixed gear would substantially diminish the craft's capabilities. I don't think you can simply put a standard "quantification" to the economical benefit because in the end, the benefit/detriment of having a fixed gear vs. retractable gear really depends on the aircraft.

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  • $\begingroup$ And don't forget, there's two types of RG pilots - those who have, and those who will. (land gear up, that is - and not always of their own making). If you really want to move fast, put on a turbo, or turbonormalizer, to maintain sealevel engine HP up into the lower drag atmosphere, up where O2 is needed. I'm good with less maintenance, lower insurance, and hopefully speed increase with faster fairing. Have only been to 12,500 ft once, to cross the Rockies leaving the Mount Rushmore area heading southwest. 10,500 ft is normally enough for east coast and mid-continent flying. $\endgroup$ – CrossRoads Apr 13 '18 at 17:20

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