Edson AB crash, VRS?
Crab, so what is 0.75 of the downwash of a B2 then ? having loads of time in a B3 with a line lifting I would suggest that its downwash speed is pretty close to 1000 ft plus a minute. In over a 1000 hours of lifting on a longline never experienced the " hole" or near vortex ring. What have had is getting pretty close to dumping the load a I have let the ac and load build up too much energy on a steep approach and got my energy management all wrong, ended up luckily getting the load on the ground as the FLI hit 10 banana's and a bong in the headset. No damage done aprart from a quick change of underwear and that was just the ground crew !!!!!!! Just as well I was wearing brown trousers
What you explain below is you balancing on over pitching and being lucky.
Knowing how to operate safely, you don’t need the overlimit warning to tell you that you c..ked up.
The B3‘s performance might have saved the day, but only to spend a lot of time in the hangar changing very expensive parts before going back to work.
The info is there for some "fag packet forensics".
Assumptions:
1 crew
End of the mission and heading home with "min" reserves.
Mass ~ 1500 kg
For reference use passing over the vertical pole in the perimeter fence in the video as where it all started.
Using the length of the aircraft fuselage to eyeball the height above the ground = 35 ft x ~ 3 = ~ 105 ft.
Time stamps from the video passing over the pole to impact point = ~ 5-6 seconds so ROD ~ 1000 - 1300 fpm give or take. As the 350 normally only has a standard VSI it would not indicate this rate due to lag in the timeframe involved.
Again "fag packet" calcs would point to the induced downwash velocity around ~ 1600 - 1800 fpm. Crabs estimate of ROD requiring 50-75% of your downwash is in the ballpark for VRS .
Keep in mind the lighter you are the easier it is to get into VRS due to lower disk loading and resultant lower downwash velocity.
Go and talk to a Lama pilot (not so many left) and wonder why Mr Vuichards videos always have a Lama in them?
Use the smoke after the impact to estimate the wind speed and direction versus the groundspeed after passing the perimeter vertical pole. I would guess IAS was near zero just after passing the pole at about 90 ft.
There is a pitch attitude and ROD change as it passes behind the horizontal perimeter fence pole where I am guessing it has just dawned that "something ain't right" and someone reverted to being a passenger.
As the camera tracks the aircraft pretty well watch the video with your hand covering the lower part so you remove any indication of movement and you can only see the aircraft. Would you fly this profile with zero airspeed?
As to "overpitching" which is just poor handling of power margins versus inertia - meh! If the wind was blowing the other way we wouldn't be having this convo here? All helicopters hover and climb as bad as each other at MTOM due to commercial and design specification minimums.
As many of my old crusty peers over the years have said - "If you are flying a helicopter and do not know constantly what your local wind speed and direction is - it was suggested that you just land, get out and seek employment in another field.
It is actually quite difficult to get into VRS and requires some effort to demonstrate but one day you will get lucky if you keep the effort up.
As an aside B3 blades are B3 blades and cannot be fitted to other models with the exception of maybe a 355N or NP. Yes they may look similar with grey paint but...............internally they are different. A B3 is not just a B2 with a "phat" engine. I know people who have tried unsuccessfully to put B2 blades on a B3 and had to throw away a lot of parts on discovery of their error!
Assumptions:
1 crew
End of the mission and heading home with "min" reserves.
Mass ~ 1500 kg
For reference use passing over the vertical pole in the perimeter fence in the video as where it all started.
Using the length of the aircraft fuselage to eyeball the height above the ground = 35 ft x ~ 3 = ~ 105 ft.
Time stamps from the video passing over the pole to impact point = ~ 5-6 seconds so ROD ~ 1000 - 1300 fpm give or take. As the 350 normally only has a standard VSI it would not indicate this rate due to lag in the timeframe involved.
Again "fag packet" calcs would point to the induced downwash velocity around ~ 1600 - 1800 fpm. Crabs estimate of ROD requiring 50-75% of your downwash is in the ballpark for VRS .
Keep in mind the lighter you are the easier it is to get into VRS due to lower disk loading and resultant lower downwash velocity.
Go and talk to a Lama pilot (not so many left) and wonder why Mr Vuichards videos always have a Lama in them?
Use the smoke after the impact to estimate the wind speed and direction versus the groundspeed after passing the perimeter vertical pole. I would guess IAS was near zero just after passing the pole at about 90 ft.
There is a pitch attitude and ROD change as it passes behind the horizontal perimeter fence pole where I am guessing it has just dawned that "something ain't right" and someone reverted to being a passenger.
As the camera tracks the aircraft pretty well watch the video with your hand covering the lower part so you remove any indication of movement and you can only see the aircraft. Would you fly this profile with zero airspeed?
As to "overpitching" which is just poor handling of power margins versus inertia - meh! If the wind was blowing the other way we wouldn't be having this convo here? All helicopters hover and climb as bad as each other at MTOM due to commercial and design specification minimums.
As many of my old crusty peers over the years have said - "If you are flying a helicopter and do not know constantly what your local wind speed and direction is - it was suggested that you just land, get out and seek employment in another field.
It is actually quite difficult to get into VRS and requires some effort to demonstrate but one day you will get lucky if you keep the effort up.
As an aside B3 blades are B3 blades and cannot be fitted to other models with the exception of maybe a 355N or NP. Yes they may look similar with grey paint but...............internally they are different. A B3 is not just a B2 with a "phat" engine. I know people who have tried unsuccessfully to put B2 blades on a B3 and had to throw away a lot of parts on discovery of their error!
Last edited by RVDT; 9th May 2023 at 00:52. Reason: Crap Arithmetic
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Claude's latest video is done in a Robinson.R-22.
(26) Claude Vuichard demonstrates the efficiency of the « Vuichard Recovery Technique » on a R22 - YouTube
(26) Claude Vuichard demonstrates the efficiency of the « Vuichard Recovery Technique » on a R22 - YouTube
Claude's latest video is done in a Robinson.R-22.
(26) Claude Vuichard demonstrates the efficiency of the « Vuichard Recovery Technique » on a R22 - YouTube
(26) Claude Vuichard demonstrates the efficiency of the « Vuichard Recovery Technique » on a R22 - YouTube
It’s not very scientific but I have always considered that the downwash speed of a helicopter in an OGE hover is probably equivalent to its RoD in a bucket speed auto - both steady state with no acceleration but I couldn’t prove it mathematically.
The higher the disc loadings of helicopters I have flown, generally the higher the RoD in steady state auto.
The 350 from memory is about 1800 to 2000’ per min so you would need about 900’ to say 1500’ per min to meet the first condition of VRS.
Right, here we go again. VRS and Vuichard discussions. I really hoped that was over.
@Robbie: You are so right.
VRS is a very good excuse for a pilot who finds itself in a situation where the "bottom dropped out". With that, you are pardoned, because VRS sounds like he/she was just unlucky. It is by far not as bad in the perception of peers and public, than having to say: "I messed up". Despite the fact, that he/she also "f**** up" by getting in VRS. But it is so much easier to blame a mysterious aerodynamic effect, than your own stupidity.
It is very human, to lock for another culprit. There are quite a few statements of pilots out there, where they claimed, that they lost power in the worst possible moment. But afterwards nobody finds anything wrong with the engine.
Human beings are often very bad sensors. When we are focussed on a certain task, we are capable of ignoring a lot of other things that are going on. Even though our brains are extremely powerful in processing information, our brain is optimised for efficiency, not processing information in parallel. When we are tired, the brain shuts down even more unimportant informations. That is the precise moment, when we are surprised by something we did not expect to happen and our reaction time becomes a lot longer. In our case here, it is exactly why in the end, the question if it was VRS or not, is really not important, because in either case, the result is the same. The big mistake was made when the pilot decided to come in fast with a tailwind. When the "bottom dropped out", he was too surprised to do anything that could have saved the day in the altitude he had left. And bang.
I am certain, Transport Canada will find out what happened, but just using probabilities, I can stay with my bet, that it wasn't VRS. Furthermore, the aerodynamics of VRS are much more complicated than Vuichard and pilot handbooks make us believe and I am pretty sure that in this case, it did not happen.
@Robbie: You are so right.
VRS is a very good excuse for a pilot who finds itself in a situation where the "bottom dropped out". With that, you are pardoned, because VRS sounds like he/she was just unlucky. It is by far not as bad in the perception of peers and public, than having to say: "I messed up". Despite the fact, that he/she also "f**** up" by getting in VRS. But it is so much easier to blame a mysterious aerodynamic effect, than your own stupidity.
It is very human, to lock for another culprit. There are quite a few statements of pilots out there, where they claimed, that they lost power in the worst possible moment. But afterwards nobody finds anything wrong with the engine.
Human beings are often very bad sensors. When we are focussed on a certain task, we are capable of ignoring a lot of other things that are going on. Even though our brains are extremely powerful in processing information, our brain is optimised for efficiency, not processing information in parallel. When we are tired, the brain shuts down even more unimportant informations. That is the precise moment, when we are surprised by something we did not expect to happen and our reaction time becomes a lot longer. In our case here, it is exactly why in the end, the question if it was VRS or not, is really not important, because in either case, the result is the same. The big mistake was made when the pilot decided to come in fast with a tailwind. When the "bottom dropped out", he was too surprised to do anything that could have saved the day in the altitude he had left. And bang.
I am certain, Transport Canada will find out what happened, but just using probabilities, I can stay with my bet, that it wasn't VRS. Furthermore, the aerodynamics of VRS are much more complicated than Vuichard and pilot handbooks make us believe and I am pretty sure that in this case, it did not happen.
Oh God here we go. VRS or not, settling with power, Vuilchard. Where’s the guy that hates twins…..
Let’s settle an easier topic like a peace process for Ukraine.
Guys always focus on ROD for VRS, whereas it’s actually flow though the disk. A big flare downwind, to the disk is the same as ROD.
My two cents is it looks exactly like VRS and ticks all the boxes.
Let’s settle an easier topic like a peace process for Ukraine.
Guys always focus on ROD for VRS, whereas it’s actually flow though the disk. A big flare downwind, to the disk is the same as ROD.
My two cents is it looks exactly like VRS and ticks all the boxes.
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It's funny that most of you are talking about the same thing, but have different vernacular!
In the US FAA Land Settling With Power (SWP) is what we used to demonstrate, and is the same as Vortex Ring State (VRS) we demonstrated in Canada... Power Settling would be the same in both jurisdictions...
The requirements to enter SWP/VRS as per the Transport Canada textbook is speed less than ETL, some power applied, and a rate of descent greater than 300 feet per minute. It doesn't take much. This looks like that, but obviously that will have to be sorted by the experts.
Funnily enough, on any PPC in Canada you usually have to talk about 3 things in some detail, those being Vortex Ring State, Loss of Tail Rotor Effectiveness, and lastly Power Settling. In the 20 years I've had PPC's I've had to talk through all 3 every time...
In the US FAA Land Settling With Power (SWP) is what we used to demonstrate, and is the same as Vortex Ring State (VRS) we demonstrated in Canada... Power Settling would be the same in both jurisdictions...
The requirements to enter SWP/VRS as per the Transport Canada textbook is speed less than ETL, some power applied, and a rate of descent greater than 300 feet per minute. It doesn't take much. This looks like that, but obviously that will have to be sorted by the experts.
Funnily enough, on any PPC in Canada you usually have to talk about 3 things in some detail, those being Vortex Ring State, Loss of Tail Rotor Effectiveness, and lastly Power Settling. In the 20 years I've had PPC's I've had to talk through all 3 every time...
The problem I've always had with VRS, is that we always practice the recovery from a 2,000' hover. Something tells me the aircraft is going to feel very different in a tailwind approach where you think you have enough airspeed,...and I'm curious as to how the Vuichard technique would handle that?
Anyway, I'll never have a fat enough logbook (or wallet) to crash an Astar, so I can only guess here, but my money is still on, that he came in too hot and waited too long to start slowing down.
Anyway, I'll never have a fat enough logbook (or wallet) to crash an Astar, so I can only guess here, but my money is still on, that he came in too hot and waited too long to start slowing down.
You can come in too hot downwind and get away with it if you are shallow (or level) and understand you will need more power than doing it into wind. Your flare will have little effect once you lose ETL as you don't get the benefit of the change in relative airflow to increase rotor thrust.
If you come in steep downwind then you better not be too hot or all your problems are going to come in at the end when you really, really want to stop - you will need a lot more power to arrest groundspeed and RoD and put yourself right in the bracket for VRS ( and if you don't have enough power you will compound it by settling with power/overpitching).
Without wanting to restart the argument all over again - if you are falling out of the sky because you don't have enough power and the Nr is decaying, that is SWP. If you are falling out of the sky because you f*****ed up but haven't run out of power and Nr is normal then that is VRS.
You can experience both and either one can lead to the other which is often the cause of much confusion.
If you come in steep downwind then you better not be too hot or all your problems are going to come in at the end when you really, really want to stop - you will need a lot more power to arrest groundspeed and RoD and put yourself right in the bracket for VRS ( and if you don't have enough power you will compound it by settling with power/overpitching).
Without wanting to restart the argument all over again - if you are falling out of the sky because you don't have enough power and the Nr is decaying, that is SWP. If you are falling out of the sky because you f*****ed up but haven't run out of power and Nr is normal then that is VRS.
You can experience both and either one can lead to the other which is often the cause of much confusion.
@Winnie: A few years ago, the FAA finally caved in. In the new Helicopter Pilot Handbook published by the FAA, it is called VRS.
For this case here, one might consider the following. In a flare, you do not use a lot of power, if you come in really hot, the collective might even be on the floor. Otherwise you balloon up up and away and with it your NR. The rotor is therefore in a windmill state. In this state you can not have VRS. As you can not have VRS in an autorotation. VRS can only develop, when you bring in power and since the vortices need time to build up, it will not be immediately in the VRS state. But the surprise was, that the flare did not bring the intended result, i.e. stop the forward speed and the descend rate, the floor came up faster than the pilot could bring in the power and develop any meaningful VRS. The PROBABLE cause of the accident was NOT VRS. The probable cause was a tailwind approach with way too much wind where the pilot did not anticipate the higher than normal sink rate. This kind of accident happened many times over the years. One is even documented on film by Robinson. During certification testing, the FAA pilot flared aggressively, levelled the ship and hit the ground. The blades folded down and chopped of the tail. The FAA pilot jumped out an threw his helmet on the ground. He wasn't a happy camper. And that was into the wind. I asked some more knowledgeable pilots if that could have been caused be VRS and the answer was no. It was HTG (Hit The Ground).
For this case here, one might consider the following. In a flare, you do not use a lot of power, if you come in really hot, the collective might even be on the floor. Otherwise you balloon up up and away and with it your NR. The rotor is therefore in a windmill state. In this state you can not have VRS. As you can not have VRS in an autorotation. VRS can only develop, when you bring in power and since the vortices need time to build up, it will not be immediately in the VRS state. But the surprise was, that the flare did not bring the intended result, i.e. stop the forward speed and the descend rate, the floor came up faster than the pilot could bring in the power and develop any meaningful VRS. The PROBABLE cause of the accident was NOT VRS. The probable cause was a tailwind approach with way too much wind where the pilot did not anticipate the higher than normal sink rate. This kind of accident happened many times over the years. One is even documented on film by Robinson. During certification testing, the FAA pilot flared aggressively, levelled the ship and hit the ground. The blades folded down and chopped of the tail. The FAA pilot jumped out an threw his helmet on the ground. He wasn't a happy camper. And that was into the wind. I asked some more knowledgeable pilots if that could have been caused be VRS and the answer was no. It was HTG (Hit The Ground).
All valid points Rotorbee but where is the harsh flare in the 350 video? There isn't one and what little flare there is comes way too late and is very small.
If he had been shallow and fast I would completely agree with you but he was steep and slow and right in the bracket for VRS.
If he had been shallow and fast I would completely agree with you but he was steep and slow and right in the bracket for VRS.
I've never liked terms such as "not enough power", "running out of power", and "power required exceeds power available", because these terms seem to put the blame on the aircraft, when its clearly the pilot who's at fault.
If you "don't have enough power" its because you're too heavy for what you're trying to do.
If you're "running out of power" its because you either waited too long to start slowing down, or you've entered the Vortex Ring State.
If you "don't have enough power" its because you're too heavy for what you're trying to do.
If you're "running out of power" its because you either waited too long to start slowing down, or you've entered the Vortex Ring State.
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Oh God here we go. VRS or not, settling with power, Vuilchard. Where’s the guy that hates twins…..
Let’s settle an easier topic like a peace process for Ukraine.
Guys always focus on ROD for VRS, whereas it’s actually flow though the disk. A big flare downwind, to the disk is the same as ROD.
My two cents is it looks exactly like VRS and ticks all the boxes.
Let’s settle an easier topic like a peace process for Ukraine.
Guys always focus on ROD for VRS, whereas it’s actually flow though the disk. A big flare downwind, to the disk is the same as ROD.
My two cents is it looks exactly like VRS and ticks all the boxes.
VRS is related to a re-circulatory flow field down through the rotor disk, and that means it isn't encountered in an autorotative state, which is what arises in a big flare downwind. Now, coming out of the flare, there is an increased thrust requirement, a skittish directional stability issue, and a need to still counter the tailwind condition if you are external referenced.
Last edited by fdr; 22nd May 2023 at 01:41.
Meh, we're all kinda missing the point here. He crashed because he came in on a tailwind and didn't adjust his technique accordingly. So, the real question is, why did he do that?
Anyway, they should make it mandatory that pilots who crash must go on social media to explain themselves.
Anyway, they should make it mandatory that pilots who crash must go on social media to explain themselves.
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Robbiee, you are not wrong. We can argue about VRS or overpitching till the cows come home, but the reason why this accident happened does not lie in those two single states.
Crab, I think we are missing a crucial information here. What was the wind speed? From the very blurry picture what could be a wind sock, I would estimate the windspeed around 10 to 15 kts. Could be worse. But did he fly at that speed? What did he see on his speed indicator? Did he look at it? When he flared higher up, did he feel the loss of ETL?
If the windspeed was higher by a certain amount than the speed of the helicopter, then there is no VRS. I think I see the ship turning a bit and if that was the case, he would have a slight side wind. In that case again VSR would be very unlikely. Those vortices are not so stable and are easily blown away. We also do not know how heavy the ship was. There is the possibility that with that side wind and high gross, there wasn't just enough power left to stop the descend.
These are all things we do not know and who could change the picture radically.
Crab, I think we are missing a crucial information here. What was the wind speed? From the very blurry picture what could be a wind sock, I would estimate the windspeed around 10 to 15 kts. Could be worse. But did he fly at that speed? What did he see on his speed indicator? Did he look at it? When he flared higher up, did he feel the loss of ETL?
If the windspeed was higher by a certain amount than the speed of the helicopter, then there is no VRS. I think I see the ship turning a bit and if that was the case, he would have a slight side wind. In that case again VSR would be very unlikely. Those vortices are not so stable and are easily blown away. We also do not know how heavy the ship was. There is the possibility that with that side wind and high gross, there wasn't just enough power left to stop the descend.
These are all things we do not know and who could change the picture radically.
As an aside B3 blades are B3 blades and cannot be fitted to other models with the exception of maybe a 355N or NP. Yes they may look similar with grey paint but...............internally they are different. A B3 is not just a B2 with a "phat" engine. I know people who have tried unsuccessfully to put B2 blades on a B3 and had to throw away a lot of parts on discovery of their error!
As for the B3 not being a B2 with a big engine, I'll ask, what's so different with it besides it all got a lot simpler to operate and with better performance?
As for relevant info for this thread.
METARs UTC -6 DST
CYET 050156Z AUTO 16022G32KT
CYET 050211Z AUTO 17016G34KT
Runway is 07/25 and the buildings in the background are located on the north side of centreline.
Good thing the pilot only sustained minor injuries, as it could have got a lot worse.