# Aerodynamic term I had not heard of until now

Discussion in 'Pilot Training' started by AggieMike88, Jan 28, 2019.

1. ### AggieMike88Touchdown! Greaser!

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The original "I don't know it all" of aviation.
Studying for CFI Written.... New word is "Phugoid"

Wikipedia explanation: https://en.wikipedia.org/wiki/Phugoid

A phugoid or fugoid /ˈfjuːɡɔɪd/ is an aircraft motion in which the vehicle pitches up and climbs, and then pitches down and descends, accompanied by speeding up and slowing down as it goes "downhill" and "uphill". This is one of the basic flight dynamics modes of an aircraft (others include short period, dutch roll, and spiral divergence), and a classic example of a negative feedback system.​

Test question was

If the airspeed increases and decreases during longitudinal Phugoid oscillations, the aircraft

... is maintaining a nearly constant angle of attack​

2. ### RyanbFinal ApproachPoA Supporter

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hmm can’t say I have either.

3. ### CC268Final ApproachI ♥ Banners

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Yep the phugoid mode. It is a dynamic mode (dynamic stability). Learned about it in my Aerosytem Dynamics class.

Phugoid Mode
Short Period Mode
Dutch Roll
etc

It's been several years now, but I remember having to calculate stability matrices, eigen vectors, etc, which I guess mathematically described the dynamic stability of an aircraft. I don't remember much anymore though

The PHAK doesn't discuss Phugoid or Short Period modes. At least not in Chapter 5.

Last edited: Jan 28, 2019
4. ### Stingray DonPattern Altitude

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I think I had a phugoid once. Fortunately, the doctor was able to surgically remove it.

Last edited: Jan 28, 2019
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5. ### kylebEn-RoutePoA Supporter

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That was the "Scientificy" word Jim Campbell used in every flight review of every aircraft he tested or claimed to test. I got bored with it 20+ years ago.

6. ### TantalumEn-Route

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7. ### PaulSFinal Approach

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It's an engineering term that does not belong on a pilot's exam in my opinion. I was flustered with the IR written's obtuse questions, especially with the questions that had more than one correct answer where you had to select the answer that was "more correct".... smh. The material is difficult enough without trying to get slick with the questions.

8. ### AggieMike88Touchdown! Greaser!

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The original "I don't know it all" of aviation.
At least I haven't yet seen "ahenway"

9. ### maj75Pre-Flight

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10. ### PaulSFinal Approach

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What's ahenway??? It's pretty damn close though.

11. ### kathLine Up and Wait

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Like you, I had never heard of it before I started studying for the CFI written.

12. ### AggieMike88Touchdown! Greaser!

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The original "I don't know it all" of aviation.
See Maj75's response.

A good joke to pull on someone when they aren't paying attention.

13. ### AggieMike88Touchdown! Greaser!

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The original "I don't know it all" of aviation.
Might make for an interesting bumper sticker....

"I'm proud of my honors Phugoid"

"Don't laugh, it's Phugoid"​

14. ### midwestpa24Cleared for Takeoff

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A CFI candidate is supposed to have a more in-depth level of knowledge than the average pilot, hence this question appearing on the CFI written.

That being said even the PPL writtens have gotten a little ridiculous with their questions. I have had several students recently coming back scratching their head on certain questions with multiple correct answers, or calculation questions where after doing all the math we came up with 120 for example, but the given answers are 118 and 122. Splitting hairs when having to use performance grid charts or sectionals.

15. ### drjcustisPre-Flight

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I had a Cessna Cardinal that had significant, persistent phugoid oscillations. Bothered me for 2 years before a CFI taught me the term and how to handle them. Flying became much easier.

Sent from my iPad using Tapatalk

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16. ### maj75Pre-Flight

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“My Phugoid can beat up your Honor Roll student.”

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17. ### dtuuriEn-Route

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It's on Pg 3-11. Personally, I used to demonstrate them to students in lesson two or three.

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Hmmm. Go read up on United 232...

19. ### Bill WatsonPattern Altitude

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...and the difference between that p thing and PIOs is?

Sent from my iPad using Tapatalk Pro

20. ### AggieMike88Touchdown! Greaser!

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The original "I don't know it all" of aviation.
Maybe redo this well known SNL sketch...

And substitute Phugoid for that.... other word

Bob: Hey guys!

Jack: Hey, Bob! Hey, your Phugoid looks great today.

Bob: Thanks, Jack. Yours too.

Ted: Hey, Bob.

Bob: Hey, Ted. How’s your Phugoid?

Bob: Good. Hey, I’d like you guys to meet Doug.

Jack: Hey, Doug.

Doug: Hey, guys.

Jack: Hey, pretty small Phugoid there, Doug.

Doug: Huh?

Ted: Yeah. You could pick a lock with that Phugoid.​

21. ### Let'sgoflying!Touchdown! Greaser!PoA Supporter

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ha, used the word not 2 days ago.

22. ### kylebEn-RoutePoA Supporter

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A PIO is you (the pilot) destabilizing things or amplifying the oscillations.

The phugoid is a measure of the airplane's own ability to damp out off-speed or off-pitch excursions (generally measured from when a steady state condition was disturbed). So, you're cruising along all trimmed out and you pull the yoke to a pitch-up which costs the airplane 10 knots. How many climb/descent cycles will it take until the airplane returns to steady-state?

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23. ### Bill JenningsTouchdown! Greaser!PoA Supporter

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Mucinex. Clears that phugoid right up!

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24. ### benyflyguyCleared for Takeoff

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Thought you could just get away with some penicillin for that...

25. ### Greg BockelmanAdministratorManagement Council Member

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Yeah. That was the first time I heard the term.

26. ### PaulSFinal Approach

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Lol, I was being your straight man.

27. ### naugaPattern AltitudePoA Supporter

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Nauga,
and the reason your slick airplane is a b***h to trim in cruise

28. ### tawoodPattern Altitude

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So is asking, "You got any updoc?"

29. ### WalboyLine Up and Wait

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30. ### RyanbFinal ApproachPoA Supporter

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What’s up doc???

31. ### PaulSFinal Approach

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Did you look under there?

32. ### bluesideupPre-takeoff checklist

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Hi everyone.
Some of you guys have too much free time on your hands, but it can be fun to read.
Phugoid / slow oscillations are very likely the one things that we, pilots, encounter more often that anything in flying, and never really pay attention to it. Every time you level off, from climbs, descents.. there is this oscillation that occurs until the acft stabilizes / settles.
You can demonstrate it by trimming the acft and pitch up, pull up on the stick, and let go, observe, how the acft will oscillate, nose up, down, for a while and eventually stabilize. That also occurs when you get a gust, and or other external factors affecting the steady state the acft.

33. ### Clip4En-Route

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I teach 3 large ground school classes a year. The written test has changed a lot and continues to expand the topics. I blame the FAA’s decision to let the Embury Riddle type schools to influence the bank of test questions. While outdated questions have been purged, other questions beyond the knowledge required for a private pilot have been included.

34. ### luvflyinFinal Approach

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Ah, the good ol' Cardinal Crowhop

35. ### NoHeatEn-Route

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It explains the curveball pitch, in baseball.

Not sure what it has to do with aviation.

36. ### midwestpa24Cleared for Takeoff

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One of my recent ones recalled several questions on constant speed propeller operations. It's been nearly 20 years since I took a PPL written, and I don't recall that being on there. I thought that was saved for complex/high performance endorsements.

37. ### Clip4En-Route

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Not only questions on the CS operations, but the engine performance chart is for CS. Also there is a Vg diagram.

38. ### midwestpa24Cleared for Takeoff

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39. ### mondtsterPattern Altitude

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The CS prop questions on the private pilot airplane test have been there for at least 10 years now. I've always assumed they were included because no endorsement is needed to fly an airplane with a CS prop so a brand new private pilot would be qualified to fly it.

40. ### Hank SEn-Route

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I've flown a square tail 172 with a manifold pressure gage. It was weird not having a prop control or gear lever . . . .