I'm doing a manned aircraft design and make it easy to fly by making it hard to enter a pilot induced oscillation (PIO). I got a range of natural oscillation frequencies for my design in pitch, roll, and yaw, and now I'm trying to see if the period of these frequencies fall close or far away from most people's reaction time. I searched on Google, but only got data on twitch time, which doesn't seem applicable for an aircraft where some muscle power will be needed, hence my asking this question.

My reasoning is that if it falls an order of magnitude below or above the reaction time of most pilots, the aircraft will be easy to fly (as long as it doesn't go through extreme high G maneuvers). An additional question I have related to this is, how can one design an aircraft to make it difficult for pilots to enter PIO's?

  • $\begingroup$ Are you looking for commercial pilots? military pilots? General aviation guys? or everyone? The subset of people will greatly change the answer. $\endgroup$ – Dave Dec 9 '15 at 22:21
  • $\begingroup$ The average person who is not trained as a pilot. So I suppose general aviation. $\endgroup$ – user11377 Dec 9 '15 at 23:19
  • $\begingroup$ There is no need, nor reason, for a pilot to have better reactions than anyone else. So just use typical figures. Stories about super human reflexes are nonsense since a reflex is a chemical response to a stimulus which has a fixed maximum speed. It might get worse, but it can never beat the maximum. $\endgroup$ – Simon Dec 10 '15 at 8:06
  • $\begingroup$ You make it sound as if you only looked at rigid body modes. This is not enough, add elastic modes and the delay of the control system on a pilot's reaction. And keep in mind that avoiding frequency neighborhood is a necessary, but by no means sufficient step to make an airplane easy to fly. $\endgroup$ – Peter Kämpf Dec 12 '15 at 21:28
  • $\begingroup$ Would be great to know what type of an aircraft your design is. Also Fly by wire or fly by cable, etc. PIO avoidance is quite an art rather than a solved (trivial) problem. $\endgroup$ – Gürkan Çetin Dec 15 '15 at 21:51

Its a bit dated but here is a paper published by the Navy on visual reaction time you can find. Keep in mind these are navy pilots, often considered the best of the best and in peek physical condition. Based on the publish year I would suspect all subjects were male as well.

Here is another study by NATO on reaction times for pilots on low sleep.

This is a nice study comparing the reaction times of pilots to non pilots, might be of some help.

An additional question I have related to this is, how can one design an aircraft to make it difficult for pilots to enter PIO's?

This is an interesting question and in some regards could be its own question here. One of the big debates (mainly between Boeing and Airbus) is if systems like this should exist and who has the final say in terms of control deflection. Airbus takes the approach that the computers should prevent the pilot of say pulling back on the stick and stalling the plane. While Boeing generally allows pilots to be the final say and while their systems will warn of a stall you can ultimately pill back the column until the plane stalls.

In terms of how you would design something like this you would have to limit control input after an approach to oscillation was detected.

  • 1
    $\begingroup$ Unfortunately, even Airbus airplanes don't always stop you pulling the stick back and stalling the airplane. :-( $\endgroup$ – Dan Hulme Dec 9 '15 at 22:57

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.