PHUGOID EFFECT (FUGIOD)

[knxhyy]

Whilst completing my instuctor rating part of the course involed a demonstration of the fugiod effect. My instructor let go of the cyclic stick for approximately one minute. The aircraft (R22)climbed and dived three times (Scared the lift out of me)

Anybody explain the dangers

We also carried out torque turns and wing overs !!

Very green instructor 900hrs

[dave_jones49]

Since he was an instructor instructing you to be ab instructor, did you think of asking him to "explain the dangers" as he saw them?

Wow, "torque turns and wing overs !!"



[This message has been edited by dave_jones49 (edited 10 March 2001).]

[B Sousa]

Since ita R-22 and if you want to be "One Up" on him, just reach over and turn the mags off.......

[4dogs]

knxhyy,

The real danger is that you will believe that this idiot knows what he is doing!!

The potential danger is that you will go away and try to emulate some of his antics.

Ask him/her about risk management and protecting the lives of other parties...

------------------
Stay Alive,

[email protected]

[helimutt]

Due to the inherent instability and characteristics of the R22 as I know it, if you did let go of the cyclic for 1 minute, I would hope you were sitting on the ground with the engine turned off.
Demonstrating this type of thing is only going to lead to something similar to another topic posted here a couple of days ago.(showing off)
As for the idea of turning the mags off,as was also suggested, that would sort the men out from the boys.
Was this topic a joke or wind-up I wonder.

[SPS]

Dynamic instability, full of risks, too many to list and no one knows them all.

Easier to get out the cutting gun and chop off the tail on the apron, bang the mast with a hammer and simulate mast bumping too, safer by far!

[DPW]

There are old pilots and there are bold pilots, but there are no old, bold pilots...

[Multp]

There may be merit in demonstrating the phugoid effect as part of Effects of Controls, but, as others have already said, under controlled conditions. The demo shows how the helicopter is dynamically unstable longitudinally. This should link into ground studies, but more importantly to the pilot's need make continual small control inputs to select and maintain an attitude. On aircraft where there is a stability augmentation system, these inputs are being made upstream of the stick position by the system.
I'm intrigued and a little worried at any suggestion that the cyclic should be let go of. Certainly NOT in the R22, nor in any other aircraft without a stick trim that will hold the cyclic.(And even then the hand should be hovering over the cyclic.) If there is no stick trim the demo can be achieved by freezing the cylcic position and observing the result. The whole point should be that the phugoid in a helicopter is divergent, and that each successive cycle will result in greater pitch attitudes. There is thus no need to pursue this, if you want to make the point, more than about one and a half cycles. More than that starts to worry me...and I've done this professionally as a test pilot.
Note that there will be cross-coupling effects of roll and yaw as well.
Given the R22's dislike for low-g manoeuvres, overall it's an exercise best avoided and certainly not one that should be prolonged.

[This message has been edited by Multp (edited 10 March 2001).]

[CTD]

To demonstrate a phugoid one must have dead clean air, and an aircraft which is otherwise longitudinally stable (c/g shifts etc). The R22 is so light and squirrely that a one knot gust of wind will have an effect on its stability. If one of you drops his pencil, never mind fidgets around in his seat, it changes the long c/g of the ship. Therefore I believe what you saw was a demonstration of misinformation, and possibly self importance, but not a phugoid.

[hover lover]

Won't dare say anything about the wisdom of the 900 hour CFI .. .. But is it not part of the testing that all aircraft go through in order to obtain certification, that the aircraft has to be placed in an unusual attitude / then hands off the controls / and aircraft must demonstrate an ability to 'right itself' or try to regain a stable position, without additional inpiut from the pilot?

[helimutt]

Hover Lover
I would say that your idea for certification is wrong.
An R22 certainly won't "right itself" if you let go of the controls. All its going to do is spoil your day if you try it.
Statically stable, Dynamically unstable.!!!

[SPS]

If the cyclic is let go the R22 will actually return itself to a position other than the original, in that it will fall in a heap on a different piece of ground than it took off from. Statically neutrally stable?

It will also stop pitching, yawing and rolling eventually (when it hits the ground)
so maybe it is Dynamically stable after all.

What it isn't is Structurally stable as it will be in a number of pieces when it stops.
And likely so will be its Pilot.

Am I making a joke out of this?

Maybe, but if it gets the message over then is it wrong to do so?

900hrs or not, Mr CFI might not get to 1000
if he keeps doing this. A point of note is that during my training in both UK and later
in NZ for the NZ inst rating I learned of the deaths of TWO of my (current then)instructors. Both of them where the 'Cavalier' type, although wonderful chaps and good pilots.

Think on ......

[knxhyy]

Maybe i did not clarify the situation it is myself the 900 hr green instructor. The pilot in command is twenty thousand plus / 40 years exp and probably the most expericened instructor in the south of england

[SPS]

My UK IE had (has) 36,000 hrs, also 40yrs plus exp. and doesn't do it.

Harry Knapp had 20K plus and died demonstrating negative G.

Each to his own, but I know where mine is.

[whatsarunway]

has he ever heard of negative g ?

ive never heard anything more dangerous and frankly, quite scary.

ditto Old and Bold saying

[helimutt]

to knxhyy
So the instructor isn't too "green" then.

[HeliEng]

What height were you at, at the time of this hands off demonstration?

[knxhyy]

Helieng,

3000ft AGL plus. the stick was closely monitored at all times.

SPS.

We don't know if Harry Knapp was demonstrating low g ?

The reason for the 75% mag check on both the R22 & R44 is noise abatement. No other reason. I got this info straight from a factory employee.

[Hoverman]

I think a few of us thought it was your instructor who only had 900 hours. Now you've cleared that up, there's only one instructor I can think of who fits your description of "twenty thousand plus / 40 years exp and probably the most experienced instructor in the south of england."
If I'm right, that changes things dramatically. You were with one of the top heli instructors in the world. Almost all his "20,000 plus" hours over 40 years have been as an instructor/examiner. His knowledge and experience of the characteristics and handling of the R22 is second to none.
Whether the 'average' instructor should do the same thing is a very different matter but, if I'm right, you were in safe hands.

[This message has been edited by Hoverman (edited 12 March 2001).]

[SPS]

knhxyy

Thanks for the info on 75%.

There are only two men that could fit that description (I think). I've flown with both and would trust them to do it but it does not mean I would, that's all.