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Considering that P-factor is a result of differing angles of attack of the blades on an airplane's propeller, I would imagine that if there was a design that could control the pitch of each individual blade as it went around the arc, much like cyclic control on helicopter rotors, the thrust-line could remain centered on the propeller by a system that can measure the angle of attack and adjust the blade angles to have the same AOA during the down-swing and the up-swing.

Has this been attempted, did it work, or is it known to be an impractical design due to the high speed of these moving parts or some other reason?

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  • $\begingroup$ Interesting idea! The blade would be changing pitch back & forth hundreds of times each second, every second that it's running, but that doesn't mean it couldn't be done if the motivation was there. Will be interested to see any answers to this. $\endgroup$
    – Ralph J ♦
    Commented May 28 at 18:20
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    $\begingroup$ Hmmm, seems like a design trade. Cost, complexity, weight, failure mode vs. not having to control it with pedal and/or yaw trim. $\endgroup$
    – AeroAndy
    Commented May 28 at 18:40
  • $\begingroup$ Large model helis' rotor rpm is close to full-scale airplane prop rpm, so high speed isn't a concern. Aerobatic ones go up to 4000 rpm. $\endgroup$
    – Camille Goudeseune
    Commented May 28 at 19:37
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    $\begingroup$ You should consider the other ways p-factor has been addressed in designs. Trim tabs, mounting the vertical tail at an angle, mounting the engine thrust line at an angle, etc. are all passive means. The AT-6 Texan II (turboprop trainer) incorporates a digital control loop of some sort to take out the p-factor -- so the novice pilots don't learn habits they won't need on jet aircraft. It seems there are many simpler ways to do this. $\endgroup$
    – Rob McDonald
    Commented May 28 at 21:37
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    $\begingroup$ Might be cheaper to just build a counter-rotating propeller than to try to design a hub that can customize blade angle based on clock position. Unless perhaps, a prop with individual electric servos within the hub to drive each blade, managed by a computer. $\endgroup$
    – John K
    Commented May 29 at 2:08

2 Answers 2

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if there was a design that could control the pitch of each individual blade much like cyclic control on helicopter rotors, the thrust-line could remain centered on the propeller. Has this been attempted, did it work?

Yes, having a swashplate to control a propeller not only has been attempted but it routinely works pretty well on any V-22 :-)

Anyway, having the V-22 two contra-rotating and mutually connected propellers, the swashplate doesn't need to be used as you intend when it flies like an airplane rather only to control the collective pitch.

I suppose that the same system might be used on a GA airplane as well. Anyway the passive tricks already implemented to counteract the p-factor (tailplane at an angle, proper trim, training, ...) are definitely more simple, cheap and reliable than a swashplate.

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So, let me try to explain two things: P-factor or Asymmetric Blade Effect is a effect that occurs when the blade that moves downwards tend to produce more thrust its counterpart blade(blade that goes upwards). The second explained thing is having 'Cyclic Blade-Pitch Control' which refers to the ability of changing the pitch angle of each propeller blade individually and dynamically as it rotates around the hub. It is commonly observed in helicopters to manage the rotor's thrust vector, but less common in fixed-wing aircraft.

After the explanation of these two things, we can try to consider the practicalities of this question. First, designing a system that can encompass 'Cyclic Blade-Pitch Control' needs a precise mechanical and electronic controls. This increases the complexity of the design in the present.

Second, the design must persevere the mechanical and operational stresses of flight and the complexity can cause potential for disaster or failure.

Third, there is no evidence that we have the advanced technology to achieve this control system for a commercial aircraft.

Forth, the complex design, based on this question, will be one of the most expensive designs in the history. Probably, no one is gonna take the risk of designing a complex design that needs a futuristic approach with an expensive development cost and unwarranted safety implementation.

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    $\begingroup$ I didn't downvote but the swashplate normally found in any helicopter and that let the blades change pitch cyclically is no "advanced" or "futuristic" technology $\endgroup$
    – sophit
    Commented Jun 2 at 18:08
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    $\begingroup$ I'm not sure how you go from "common in helicopters" to "one of the most expensive designs in history". Did you use generative AI to write this answer? $\endgroup$
    – Sanchises
    Commented Jun 2 at 18:11
  • $\begingroup$ 1, For sophit: The swashplate's normally found in any helicopter, as you said, is common for helicopters, but when it comes to commercial aircrafts or other developed aircrafts, its use in the aircraft's design is gonna ask for a lot of mechanical and electrical effort. For Sanchises: The design for a helicopter and a commercial aircraft differs in many things, and I wanted to mention the swashplate's unwarranted usage in the aircraft, considering how difficult it is to implement it in a normal aircraft(excluding helicopter). I used what I read + critical thinking, for your knowledge. $\endgroup$
    – Aviation Club Aviators
    Commented Jun 3 at 13:45
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    $\begingroup$ Why should the mechanical and electrical effort be higher than in a helicopter? Propeller blades are generally much lighter and generate much less thrust than a helicopter one, the opposite might actually be true... $\endgroup$
    – sophit
    Commented Jun 3 at 15:41
  • $\begingroup$ FOR SOPHIT: The mechanical and electrical effort can be higher than a helicopter since I was referring to commercial aircrafts. It's obvious that commercial aircrafts need more force, thus more effort. $\endgroup$
    – Aviation Club Aviators
    Commented Jun 5 at 16:42

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