R22 rotor decay below 50 kts
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and the only thing I saw that jumped out at me is that he mentions that you are in Ring Vortex State when doing a zero speed autorotation
You are safe from VRS in a virtical decent while in autorotative condition.
Just be sure to be flairing ( arresting your decent rate with collective) at ground level, or you get past translation speed before you pull up collective.
Dureing a vertical decent, your decent rate is too high for a ring to develop.
You are safe from VRS in a virtical decent while in autorotative condition.
Just be sure to be flairing ( arresting your decent rate with collective) at ground level, or you get past translation speed before you pull up collective.
Dureing a vertical decent, your decent rate is too high for a ring to develop.
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MOSTAFA ??? I was agreeing with your reference to me, what are you talking about??? "I certainly wasn't referring to Crab." did I say I thought you were? You alumni of CFS seem to share some common characteristics. You ARE enthusiastic, and self confident, perhaps slightly challenged in comprehension?
I think you'll find Crab is talking nonsense again.
WRT your confusion about whether I have "ever proved anything right"
Refer to the graph I have posted above and observe how it DISproves crab's assertion, and thereby YOU, wrong.
Rates of descent in Zero Speed Auto are not a matter of only 3-500fpm greater than at Vy.
MOSTAFA You actually got something to say on the topic or are you just talking part in the Mod supported insult campaign? If you don't think VR is something you can get trapped in for 4000ft then you are not in the self congratulatory self re-enforcing delusion club. Nothing to say on the topic? just here to throw insults at me to support your school friend? I'll probably get in trouble again for your uncalled for, off topic, irrelevant pathetic misunderstanding. Mod please feel free to Mod out MOSTAFAs uncalled for insults, then you can delete this paragraph too ?
I think you'll find Crab is talking nonsense again.
WRT your confusion about whether I have "ever proved anything right"
Refer to the graph I have posted above and observe how it DISproves crab's assertion, and thereby YOU, wrong.
Rates of descent in Zero Speed Auto are not a matter of only 3-500fpm greater than at Vy.
MOSTAFA You actually got something to say on the topic or are you just talking part in the Mod supported insult campaign? If you don't think VR is something you can get trapped in for 4000ft then you are not in the self congratulatory self re-enforcing delusion club. Nothing to say on the topic? just here to throw insults at me to support your school friend? I'll probably get in trouble again for your uncalled for, off topic, irrelevant pathetic misunderstanding. Mod please feel free to Mod out MOSTAFAs uncalled for insults, then you can delete this paragraph too ?
Last edited by AnFI; 27th Dec 2016 at 14:08. Reason: adding DIS
Erm...
To be in VRS you must have three things, bit like a fire triangle. ROD <3-400 fpm/AS >12-15 its(below translation)/Power in use.
In autorotation, you have no power in use, therefore cannot be in VRS. Simples...Surely?
To be in VRS you must have three things, bit like a fire triangle. ROD <3-400 fpm/AS >12-15 its(below translation)/Power in use.
In autorotation, you have no power in use, therefore cannot be in VRS. Simples...Surely?
Chief Bottle Washer
or are you just talking part in the Mod supported insult campaign? If you don't think VR is something you can get trapped in for 4000ft then you are not in the self congratulatory self re-enforcing delusion club. Nothing to say on the topic? just here to throw insults at me to support your school friend? I'll probably get in trouble again for your uncalled for, off topic, irrelevant pathetic misunderstanding. Mod please feel free to Mod out MOSTAFAs uncalled for insults, then you can delete this paragraph too ?
And as also has been pointed out to you, it is time to recognise that you get responses based on what you post. When you choose to be rude or disparaging to others it is not unexpected that you be treated in a like manner.
Any further comments along these lines criticising the moderating of PPRuNe will be removed, as will off topic poor-me rants (apart from this which is left for others to see your attitude and judge accordingly).
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How can any trained helicopter pilot believe they can be in vortex ring state at any speed during autorotation? Putting aside the basic physics of a rotory wing, try thinking about it practically? Surely pilots would be trained to avoid zero airspeed autos at all cost if vortex ring was even a remote possibility? Why would you want to be hurtling towards the ground at an uncontrolled rate of descent when you've suffered an engine failure? I've flown the R22 in autorotation and autogyros which are always autorotating. They most definitely do not enter vortex ring state during autorotation at any speed, and the ROD at zero airspeed is nothing like double that at 53kt.
Paul Cantrell
My copy of Prouty doesn't say that, he highlights the difference between VRS (power applied with moderate RoD), and windmill brake state where all the flow is from beneath the disc and the rotor is extracting the energy to keep turning from that flow. Will there be recirculation at the tips - yes but it doesn't mean you are inducing a flow top to bottom with power.
You may well be correct that the R22 has a different drag curve to other helos with higher disc loading.
There is no doubt that the RoD in a zero speed auto is higher than at bucket speed - the only element for discussion is how much. In every helo I have flown (with widely differing disc loadings and AUMs) the RoD at bucket speed is between 1800 and 2500 f/min and the zero speed RoD doesn't vary by more than 500 f/min from that figure when in steady state.
I mentioned fuel flow graphs only because of the identical shape on the ones I have seen to the power required curve - since the power required curve is exactly what it says, then in powered flight the engines(s) are always providing driving force (if only to overcome rotor profile drag).
As I mentioned, Prouty claims that at zero airspeed in autorotation you are actually in Ring Vortex State which says recirculation is taking place...
You may well be correct that the R22 has a different drag curve to other helos with higher disc loading.
There is no doubt that the RoD in a zero speed auto is higher than at bucket speed - the only element for discussion is how much. In every helo I have flown (with widely differing disc loadings and AUMs) the RoD at bucket speed is between 1800 and 2500 f/min and the zero speed RoD doesn't vary by more than 500 f/min from that figure when in steady state.
I mentioned fuel flow graphs only because of the identical shape on the ones I have seen to the power required curve - since the power required curve is exactly what it says, then in powered flight the engines(s) are always providing driving force (if only to overcome rotor profile drag).
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Thank you to the moderator for pointing out that I get a little bad tempered in responding. Quite right - very sorry.
In the humblest way possible I would like to state my view that the RoD in Auto at Zero Speed is not a matter of only (300 to) 500fpm more than at Vy.
I have included a graph which shows that clearly. I could of course be wrong, it only is my view, and not my graph.
I'll report back with a substantiated figure. Unless AOTW is going to get there first? (not easy because it maybe 'off the clock' and would need a stop watch)
(Then perhaps people can stop sending me threats?)
In the humblest way possible I would like to state my view that the RoD in Auto at Zero Speed is not a matter of only (300 to) 500fpm more than at Vy.
I have included a graph which shows that clearly. I could of course be wrong, it only is my view, and not my graph.
I'll report back with a substantiated figure. Unless AOTW is going to get there first? (not easy because it maybe 'off the clock' and would need a stop watch)
(Then perhaps people can stop sending me threats?)
Having had play at zero speed autos today in a 365 I might have to up my upper end of RoD towards 1000 ft/min greater than bucket speed - 2300 f/min at Vy and 3100 ft/min at zero speed was today's comparison.
Not surprising I suppose that a higher disc loading helo should need a higher RoD to keep the blades turning and perhaps that smaller 'parachute' is more sensitive to forward speed (or lack of it) in auto - hence the greater variation.
Not surprising I suppose that a higher disc loading helo should need a higher RoD to keep the blades turning and perhaps that smaller 'parachute' is more sensitive to forward speed (or lack of it) in auto - hence the greater variation.
