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Gyrocopters feature a free spinning rotor that generates lift. In this design I have included four free spinning rotors inside the wing of a Cessna 172. Although it will not allow it to take off vertically, it should allow a slow take off and approach.

It all depends on how much lift is generated, how much the system will weigh and if there will be any controllability problems.

This is different from the Ryan XV-5A that had powered rotors in the wings.

3D model of proposed STOL modification in a Cessna 172

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  • $\begingroup$ what have you tried? why can't you answer yourself? this looks like a project question and you are asking to finish your project for you. $\endgroup$ – Federico Aug 12 at 11:00
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    $\begingroup$ I don't see an actual question here. I do see a deep misunderstanding of how autogyro rotors produce lift. $\endgroup$ – Zeiss Ikon Aug 12 at 11:04
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    $\begingroup$ I see a question; the title is a question. That said, I'm not sure it's an answerable question, especially with only the answer given in the question body. $\endgroup$ – a CVn Aug 12 at 11:57
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    $\begingroup$ I think the question is clear here: How much will lift change with these rotors in the wing compared to the normal wing? $\endgroup$ – Bianfable Aug 12 at 12:46
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    $\begingroup$ I am not an engineer, but I imagine that if opening big holes in the wing would produce extra lift that someone would have done it by now. Federico, why don't you let someone answer? $\endgroup$ – Michael Hall Aug 12 at 16:02
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None.

What you've come up here is a just holes in the wing, which will allow high pressure air from the lower surface to escape upwards. This will both slow the plane down due to extra drag and reduce its overall lift.

An autogyro's rotor is a wing in itself, deriving spin from forward motion, and then converting spin to lift. You don't get extra lift by putting a wing inside a wing.

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From J. Gordon Leishman, Principles of Helicopter Aerodynamics

An autogiro derives its lifting force from its rotor, which is not powered by an engine but by the airstream flowing in at a positive Angle of Attack: from a relative flow that is directed upward through the rotor disk. So to an extent, the autorotating rotor provides the same function as the wing surface that was cut for mounting the rotors.

How best to compare whether the effect of the rotors is positive or negative? If we look at the L/D ratios of autogiro and fixed wing, we can identify the following:

  1. Autogiro, from Leishman: a maximum L/D of 5 for the complete machine, and of 7 for the rotor only.enter image description here

  2. Cessna 172, from this link:: maximum L/D of 10.9 for the complete aeroplane, including fixed landing gear.enter image description here

So fixed wing wins, hands down, by about a factor 2 - and that is for a large autogiro rotor which has much higher L/D than a small rotor. Plus, as @RonBeyer mentions in a comment, not cutting holes in the wing means that there is a convenient place to store fuel in.

Data and graphs from J. Gordon Leishman, Principles of Helicopter Aerodynamics, chapter 12.

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