Hmmmmm SASless using a flawed technique doesn't sound like a good tool to have in Your kit! As I said Mate & proven on 6 types, more times than I can count; this thingymebob called the Vuichard recovery method, doesn't afford a recovery at ALL from deeply developed VRS.....so the point clinging to such a method is dangerous at Best! Probably why Robinson is fully into it!

Happy landings

Add terrain into the VRS situation and sometimes going straight ahead might not be the best choice is what I am suggesting.

What is important is understanding VRS and how it affects aircraft performance....the risk it poses....and the quickest way to identify the onset and perform immediate effective recovery techniques.

Knowing how the flight control's effectiveness is affected is part of that.

This accident, and most others, have nothing to do with deeply developed VRS or anything that could be attributed to it.
Vuichard's technique was to make a recovery easier for situations where there was little altitude or suitable terrain to get the nose down.
No technique will make any difference to accidents like this where the cause is PPP.

Your ignoring the fact the Vuichard technique doesn't work in a real VRS situation! (maybe in IVRS; if Your damn lucky) Obviously be aware of surrounds & conditions & do everything You can to avoid VRS; then no recovery technique is required!

Happy landings

VF

Wes Prouty explained this in an issue of Rotortales many many years ago......VRS requires 3 things, relatively high rate of decent ( most modern helicopters about 500') partial power ( can't be in VRS in an autorotation) and low airspeed ( less than translation). Only 2 ways out, moving out of the "bubble" or full down collective and entering autorotation (usually not an option). What you do with the flight controls to get you out of the bubble will depend on many factors, but in my experience lowering the collective as much as possible and forward cyclic is the best muscle memory method.

SWP is simply not enough power ( lift) available for the flight condition, hot/ high for example.

So true Bell Ringer, nothing will save Your arse when in PPP. But You are ignoring the fact that Vuichard technique DOESN'T work in VRS; please don't take my word for it...go prove it for Yourself! & be sure You are fully established in VRS when testing this concept!

Happy landings

I am happy to take your word (you're not alone in your view), I use the conventional methods taught but have always preferred to stick to the basics and to rather plan properly.
Recovery is a poor substitute for prevention.

Bang on Mate.....If my old memory serves me it's 300fpm. But, from experience You need to have way higher ROD, more like +1,000fpm to go VRS! I don't go with lowering the club....just pole forward with power on. That's one less thing to do & I feel You get into cleaner air much faster, powers already on so away You go! The key is tilting the disc, with power on Your pulling clean air into the problem the moment You pole fwd!

SWP; that's a totally different story...pull more power (if You have it without cooking the donk) otherwise same as above pole fwd & fly away!

Happy landings

Gudonya Mate I've been twice in VRS unintended, both times due to environmental factors (localised massive updrafts) which You can't be always planned for, so being ready with a plan B recovery method is always wise!

Cheers

Yes, I said "modern" helicopters.....the S61 can easily do it at 300 ROD. Of course lowering the pole may not be practical, but if altitude allows it will actually get you out sooner and with less RRPM loss. As to SWP, that's the problem, there is no more power. Think loading your Jetbox up to gross at SL and then trying to land at 10,000 PA at +30C. Pulling more is not an option.

To get into VRS you need to be travelling downwards at over half the speed of your downwash and an S61 has far more than 600'/min downwash, more like 2000'/min.

It is all about disc loading - older helicopters had low downwash speeds because engine power was lower and the rotor had to be bigger.

Modern helos have very powerful engines and smaller rotors for the same or increased AUM.

Nick Lappos published a RoD vs Fwd speed diagram for VRS produced, I think, by the US Army. The VRS boundary was related to downwash speed - you needed 0.6 to 0.8 of your downwash speed to catch it up enough to start to ingest it.

https://www.rotorandwing.com/2011/11...wash-velocity/

well as a demo to students in an old heli ( S 300C ) fly downwind at 17"map trying to hold height She looses translational lift at around 20 kts, ROD now about 500 ft plus.Now in IVRS, Pull power up to 24 inches and guess what aircraft climbs back up again. I have to have more than about 800 ft a min for the aircraft not to be able to pull herself out of the situation

Should have added even pulling full power with nose forward I cant stop the 800ft min ROD in 50 ft or Tim Tuckers 30 ft Where am I going wrong ?

VF,

Where did I ever say I endorse the Vulchard Method?

What I have stated is an opposition to limiting VRS recovery to exactly one single method as you seem to be saying.

That kind of mindset....one size fits all kind of thinking.....is not the way life works in flying helicopters.

At altitude well clear of terrain you might be technically correct but when close to the ground you might just want to go towards a particular direction that might just in fact be not straight ahead.

You fly in some mountains....and thus probably understand there are times there might be lots of air under you to one side and lots of rock ahead and on the opposite side to the valley floor.

Would you not want to go towards the valley floor rather than the Ridgeline?

Well I can tell you from experience that the 61 can and will get into VRS at WAY less than 1000 ROD. I was shown this during my initial endorsement over 30 years ago. The instructor simply said climb up to 6000 ft, this near a coastal city and a hazy day so no real discernible horizon. Then he said come to a hover. I brought the nose up lowered the collective just as you normally would. As I was coming to but not quite to zero AS I noticed a slight ROD maybe between 300 to 500' ROD and I just added a bit of collective. Well in a split second we were coming out of the sky like the preverbal greased manhole cover. The instructor pushed the cyclic full forward so we were then looking outside thru the skylights. He said he hates doing that but wanted me to see just how easy it was to get the old girl into VRS. So, as Mr. Prouty said 300' ROD because the S61 is NOT a modern helicopter. Size and gross weight have no bearing on VRS, actually the 2 times I have been in it it was both times in an empty a/c.

Anyway, this has been beat to death......let it die.

Beat to death? It's now 20 years since I originally began it by asking for VRS stories. Long may the discussion continue. :cool:

my point exactly - in a light aircraft with a big rotor, the downwash speed is much slower as you need far less power to hover. Therefore much easier to get into VRS.

It's not about the size and gross weight of the helicopter, it is disc loading which is AUM vs size of the rotor.

I am just passing on information from the likes of Mr Lappos who generally seems to know his way round a helicopter:ok: If you don't like or believe it, that is up to you but that doesn't make it not true.

I think some of you are forgetting that a roll command would respond faster than a pitch (nose down) command. Therefore jumping sideways with pedal assist would be quicker than jumping forward when you have no airspeed!

Unless you encounter VRS from the hover in zero wind in a vertical descent or are downwind, chances are you will have some forward airspeed, even if it doesn't register on the ASI so forward will be better and quicker.

The lateral control input might change the disc attitude slightly quicker than forward but you still have the same amount of inertia in the aircraft to move and you are trying to drag it sideways through the air.

Hey CJ.....have you actually tried & tested this method? It doesn't work in deeply developed VRS! Others here have stated the same concerns! if Your just getting into it (IVRS) then You've a chance of it saving you (fingers crossed). Please read my detailed comments above on this flawed method!

Good luck Mate & Happy landings

VF

I have great respect for Nick and don't for a minute think I know more than he does about aerodynamics, but all I'm saying is that the S61 can and does get into VRS with WAY less than 1000 ROD than you suggested, that is from personal experience and I will not attempt to explain that in aerodynamical terms, only underwear changing ones ;)

crab is correct. Disc loading has a significant impact on establishing at what ROD the rotor system enters VRS. It takes a lesser ROD with an empty helicopter at the end of the fuel cycle vs. a helicopter at max gross weight.

To make a slight correction to VF's contention that the Vulchard method doesn't work in fully developed VRS: in a tandem rotor helicopter it is the smartest method, no matter on your ROD. Also, an S-64 Aircrane responds very quickly to a lateral control input to exit VRS vs. a longitudinal recovery. I've seen RODs larger than 5,000'/min and the Vulchard method works like a charm. Loggers have been doing this since the '70s.

with 50' recovery as advertised?????

Sideways recovery on a tandem rotor makes sense - both rotors in clean air

Thanks Mast Bumper (I hope You're not bumping to often) I've never flown twins let alone a Chinook, so no comment......it is not my contention alone, many others have come to the same conclusion as I! I have many times tried & tested this method on a 350, 125, 130, 206, 407 & G2 & it didn't work at all in fully developed VRS, it did have some positive effect in IVRS. The 70's aye; then Vulchard didn't invent this at all, stole an old idea claiming it was his own invention, hmmmmm :=

Have You tried this method in a light single?

Happy landings

VF

that makes a ton of sense!

But with two sets of Rotors...how many possibilities of VRS are there....Forward head only, Aft Head only, both Heads involved?

Outwest - out of interest, were the two occasions you experienced VFRs in the S61 in the same flight profile ie flaring to the high hover?

It's certainly possible. I know an RAF Chinook pilot who had a student get both fore/aft into VRS on final for a pinnacle landing in Afghanistan.

VF - not to dispute your experiences, but I personally have had good results from sideways recoveries, even at late VRS stages - that's in a Squirrel and G2 - as you say, only testing, no real-world brown underwear scenarios. Side note; I know a few instructors here in Switzerland that also have played around with both techniques over time and found the Vuichard recovery to be the better option assuming no obstacles.

In the Chinook....clever use of the yaw pedals during takeoff can produce additional lift as you accelerate the aft rotor into clean air not disturbed by the forward rotor.

I wonder how that would work in dealing with a VRS situation.

In all of the VRS demo's I ever performed during conversion training for. new pilots....I do not recall it being all that easy to get into a full blown VRS descent.

I know it was not one of the demo's that caused much excitement as I recall it being a rather benign maneuver.....but always done at 3,000 feet AGL.

In the early A model...turning off the SAS in a steepish turn was not for the faint of heart....feeling the aircraft trying to swap ends at 100 Knots was far more exciting.

I may have been misleading, I have been in it twice, once in the 61 and once in a 205. The 61 was not what you would call a flare, a simple slowing of airspeed to come to a hover at altitude, and upon noticing that what I would call a small ROD I used a small application of collective to arrest the decent and that fast we were coming out of the sky. The strange thing was the VERY experienced instructor never told me why he wanted me to come to a hover at that altitude, but he knew ( I guess from all the others he checked out) what would happen.

The other time was on a seismic longline job. I was going down the cutline ( downwind) looking for the drill and realized I had passed it. I lowered the collective and pitched up to slow to make my turn into wind and approach the drill. We had no flight instruments ( AS) on the left side or a means to jettison the belly hook from the left side so ( luckily for me) we were flying 2 crew. I obviously came to a very low AS but since I was going downwind I didn't realize this. The next thing I knew we the greased manhole cover and when I got my head back in from the bubble window both low rotor lights ( Yellow and red) were on. By this time the turn was completed and we were into wind. VERY luckily the other highly experienced pilot was pumping the collective to regain RRPM. We were now with the skids almost going thru the tree tops, and yes the longline was still attached ( remember I could not kick it off) how it did not wrap around a tree and drive us into the ground still haunts me to this day.

I have a very LARGE respect for VRS.......

Outwest - very brown trousers on that last event I am sure:ok:

NigelH - did they do a comparison of the Vuichard vs 'standard' recovery? When they used the Vuichard, did they recover in 50'?

Kiwi500 - I don't know, other than using Nick Lappos' graph, if you can put numbers on it.

However, you could liken it to a FW stall in as much as there is light buffet, which gradually increases if you don't recognise it - it gradually worsens and then finally gets to the nose drop/wing drop stage which would be roughly the equivalent of IVRS going into full VRS.

The 30 kts 500'/min RoD figures have been taught for many years as a way to avoid even IVRS but they were based on low disc loading helicopters. Each aircraft will have different figures based on its disc loading and even they will vary with AUM and DA.