What the Phugoid is Longitudinal Stability?

[@vformarallo]

That's pretty interesting i was taught this but never tested in the plane, will do next time. Great videos btw!

[@mdrocketry]

A more correct phrase would be that it wants to seek the AIRSPEED that it was at. Whatever airspeed it was stable at before is where it will try to end up. Trim is used to decide what speed you want the plane to be stable at.

[@mytech6779]

A bit more accurate that is both static and dynamic longitudinal stability. If you have increasing phugoid oscillation then there is static stability but dynamic instability. Static instability won't trend around the starting point, it continues to divert further away from the starting point with strong bias in one direction. Dynamic stability(or instability) combined with static is a bit harder to describe thouroughly in a YT comment, but it will generally effect the rate of diversion in a variety of ways; accelerating, decelerating, fixed rate, oscillating between slow and fast[but still moving in the same direction], could have enough speed oscillation to slightly reverse, and even cross back over the starting point at an extreme, though it will bias substantially in one direction.

[@byronhamby1274]

Great videos and i often use this technique as an instructor as well! I also recommend a discussion on P factor changing the heading as well, but there is a slight lag for it to take effect. I also think the basic misunderstanding of stability of an airplane leads to many loss of control accidents. Particularly the stall and spin accidents. I have been in many spins watching the pilot I was training continue pulling…. “ My controls!” Is usually heard with my CFI voice!

[@Lightblue2222]

Stable attitudes are awesome.

[@AV8OR51]

Thanks for the demo. This is something I have read sometime ago in a book called “stick and rudder” by wolfgang langewiesche

[@ahmedalbader8847]

WHAT AN AMAZING LESSON THANKS

[@n721sw]

Love your video's, wish you had shoulder harness's though.

[@ashkanfered]

Safe AV8R alert 🚧. I agree they’re well worth the investment

[@bradyreisch]

Dutch Roll mode next?

[@elarabibabas6928]

the lift vector doesnt grow , it actually drops , as far as the main wing is concerned. The angle of attack becomes negative. The only thing that actually grows is the lift vector of the horizontal stabilizer in the negative direction, that usually consists of a symmetrical or trimmed down airfoil. As soon as it grows , it pitches the aircraft. If this is what you mean , then you can just skip the comment.

[@jesusbarrientos1999]

Question regarding precession, during the oscillations I noticed slight right and left yaw, almost imperceptible. Was this force noticeable on the inclinometer? I was thinking it may be a good practice drill for PPL to familiarize themselves with rudder use in climbs and descents.

[@mach179]

Did Flash say lateral axis?

[@GoldSealFlight]

Yes. Longitudinal stability describes stability about the lateral axis.

[@mach179]

@@GoldSealFlight I guess I'm going to ask for a refund from Cal Poly-Pomona for my degree in aerospace engineering. The longitudinal axis is NOT the lateral axis. Also, I spent 34-years as an aerospace engineer at Edwards AFB.

[@GoldSealFlight]

@@mach179 Yes, the longitudinal axis is not the lateral axis. Think about the motion. It sweeps through the longitudinal axis, i.e. it pitches. But the motion is >around< the lateral axis. Contact us at [e-mail] and we'll be happy to send you a picture that will clear it up. (Wish we could post images here.)

[@geonauto]

@@mach179 we are talking about the same ,ac moves around lateral axis,if u see from a lateral standpoint

[@calebo.8132]

@@GoldSealFlight I definitely prefer >around< instead of about

[@brycemack]

Here from the book How We Decide

[@AfonsoMiranda22]

Thanks!

[@Noorjaahaan]

Perfect 👍

[@deaddropholiday]

Not so much fun when you have high-g pitch oscillation. Neck hurts just thinking about it...

[@VMCAviationVideos]

Cheez, I had to google Phugoid to see what it is