vortex ring alt + vsi
 

Just a little question
When in vortex ring state will the VSI and Altimiter read or show the helicopter is desending

Many thanks Levo.

Will they ever!!! Those hands on the altimeter will be a blurr, but you won't notice because you will be too busy Sh$%$ing your pants:eek:

Yes. Can't think of any reason why it shouldn't.
Static pressure entering the static ports isn't affected in vrs (vrs is related to air velocity through the rotor system, not static pressure), and depending upon the design of the VSI or IVSI, it will either just take static pressure change or will have an accelerometer incorporated to speed up the readings.
Outwest, remind me never to give you the controls...:uhoh:

Until you've been in VRS, no further comment required

Any screwball condition will alter the absolute accuracy of the static system, especially if the static ports see any head-on air impacts, but the high rate of descent of VRS is quite enough to be sure that you see a big indicated descent rate while in VRS.

BTW, lets uncan the great debate: VRS occurs at quite a bit more than 300 fpm, it must be about 3/4 of the rotor downwash velocity where the downwash cannot get out of the way of the descending rotor. This is always a much higher rate of descnet than 300 fpm.

Why do instructors say otherwise, and demonstrate "VRS" in slight descents that seem to "prove" otherwise? Because there is an increase in power required at 300 fpm, which can fuel a vast over-pitching that turns into VRS if left unattended. The typical VRS demonstration is actually a demo of increased ROD due to the unstable nature of a hover descent - where some ROD makes the power needed to hover rise a slight amount. When the instructor forbids any collective rise, the descent increases (not yet VRS, just a hairy increasing vertical descent) until real VRS can be experienced (at 3/4 of the downwash speed). The aerodynamics of VRS assure that it CANNOT be experienced unless the aircraft is at or near zero forward velocity and at or near the downwash velocity - somewhere above 750 ppm for a light helo, and near 1500 fpm for a big one.

The stock numbers I've always read and was taught were IAS < 40 (and in some machines, like the B206, IAS is unreliable below 40), VSI > -800fpm. I suspect that those numbers don't get one INTO VRS, but reduce the margin of safety to the point that it's a lot easier to get into VRS from that point. Nick, of course you're correct that there will be a loss of precision in static system, but even ignoring your stomach in your throat I think it will still be fairly apparent from the instruments that the machine's entering a pretty hefty rate of descent.
My experience is that interaction with such things as cliffs, ship's smokestacks and stack gas and/or other obstructions can change downwash patterns to such an extent that loss of lift can occur startlingly quickly. Whether any of that is actually VRS is probably not too important, but what is important is to predetermine how you're going to get out of it should you find yourself in it.
Outwest... a fellow I once flew with got into VRS once and tried to get into it a second time in one day while trying to descend to a SAR target with a substantial tailwind. I got us out both times precisely because he was rushing himself, target fixating and busily doing what you recommend rather than fly the machine... I would say my response was perhaps more appropriate. Ball's in your court, mate.

VRS
 

May I be so bold as to offer a few of my thoughts on VRS:

1. Levo - as already covered by Nick and Um... yes they will indicate a descent.

2. The descent rate will be high but the instruments will be readable unless you allow the situation to go uncorrected, it then becomes quite unpredictable.

3. Nick, I think the figure of 300fpm used by many instructors is, as Um... says, a sort of "alarm bell" figure, eg, I insist that during the approach, as the speed reduces through 30 kts, the rate of descent should be less than 300 fpm. Bearing in mind that this is being taught to student pilots who need bench-marks in the early days to keep them out of difficult situations.

As far as demonstrating VRS goes, what a silly idea. Just like arterial bleeding, I don't need to see it to be aware of how dangerous it is. The incipient VRS demonstrations given by instructors are aimed at showing the student how unpredictable the helicopter can be if power is applied when in a high rate of descent with low speed and how to recover from that situation by increasing speed. The demo should not be allowed to develop into anything near VRS but simply to serve as a severe warning that helicopters will bite your ar$e if you are not careful, therefore, when reducing speed through 30 kts...........etc etc.

Intentional VRS should be left to you test pilots if you feel the need.

Someone needs to lighten up......now I remember why I stopped posting here.......and I ain't your mate.

I agree... and I hope it works out that you do... as for me, I'm going surfing...
Also, you need to get out more... and get a better grip on colloquial English.
"Mate" isn't an expression that gives a lot of people offense...
I don't know why the original question was asked, but I assume unless it's clear otherwise that the original questioner asked it in earnest. I'm not sure your answer was a whole lot of use... so maybe it's best that you did stop posting... mate.

Deliberate Vortex ring is part of the annual check in the Royal Navy, and I think it is a useful reminder.
You can tell people something is scary, but until they do it for themselves, it isn't quite the same.

A dear old guy called Lofty Marshall at CFS(H) discussed VRS with me and how they used to teach it years ago, until they started filling up skips with helicopters. Do bear in mind, recovering from incipient vortex ring is not a recovery from the real deal.

Like several other exercises (EOLs and Tail Rotor problems included), they may have value, but that value has to be balanced with the training risk and the likelyhood of the actual event.

The actual event of VRS can be avoided through correct handling and awareness.

Don't get me wrong, if you want an annual reminder of the dangers to be demonstrated to you and pusser pays for it then fill your boots. I prefer to discuss it and lay down parameters that will ensure its avoidance.

:D quite agree....mate :ok: at the same time you could stop robbo,s practicing engine off,s into the deck too and we can all get an insurance rebate :ok::ok:
ps you cant get into vortex whatever speed or rate of descent without pulling power..

Just a little answer as I do them repeatledy in C& T, just today again.

Firstly, your VSI will indicate almost immediately, then it willl slow right down as you quickly get out of it. That is how that instrument works.

Your Alt will not register the event until after it has happened. That is because that instrument always is slow to wake up. It will portray it fairly well when it does though.

For your info you can look up other threads that go into the detail, but it is impossible to retain any machine in VRS for a period of time longer than; OMG it's dropping like a stone, f@@# what was that.

Please do not enter VRS below eighty feet AGL, as that is about the usual drop in a light helicopter. (inadvertant or deliberate, all tied up in the physics you know, nudge nudge, wink wink)

Any factor the balance of eighty is the only factor that will EVER remain painful.

Any factor that balances nigelh will be an freudan expression in itself. He still hasn't worked out that nearly all EOT is done in ab initio training, in R22's. Poor boy!
Perhaps he should volunteer his squirrel for this type of work?

Sorry to have to correct you mate.....

One can only recover from incipient VRS. This is because the real m'coy does not enable the pilot to take control of the a/c. It is doing its own thing and will either terminate your flight violently or recover itself long enough for the pilot to do something about it. VRS is no longer demonstrated anywhere, to my knowledge for this very reason.
Having said that, does the american pilot interpret VRS as the UK IVRS???

Now Now thomas, long time no see, how are you doing.

one can definately recover incipient VRS.

One can definately put a machine into VRS and;

one can not hold it in because the upward rushing air will simply blow the recirculating air away. savvy??

all'a'same'as the limiting coefficient of static friction.

when one puts it into VRS, the relationship betwixt airframe and rotor disc can be safely maintained under full control to the highest integrity. fear not with an experienced person.
cheers tet

VRS
 

Thomas,

I'm with you on this one, recovery from VRS is practised at the incipient stage, because the real McCoy is too unpredictable and therefore, too risky.

Topend.... I'm not sure where your 80' figure comes from, I think we must be discussing different exercises.

Tam

TOT mate...
English may be your second language ...so i shall explain s l o w l y ....
I know that eol,s are done mainly in training and therefore often in R 22,s....I am suggesting they stop doing them .....just as they have stopped demoing low g and now stopped demoing full swp..... as for using my squirrel ...i dont think you could afford it old boy :rolleyes:
ps check freudan spelling ....

vrs
 

Just another little question

When a helicopter is in a quick stop and the blabes start to (bang slap)is this vrs for a moment until you level the helicopter .
If so would this be a early indication of VRS.
Or would there be any other indication apart from falling sensation


Thanks for your replys.

Levo.

The blade slap is BVI (Blade vortex Interference) and is not even a second cousin to VRS.

Q to Nick Lappos.

Can this BVI damage the blades as it sounds awfull and is puting the machine under a lot of stress are there limits .

Thanks nick.