Vuichard again
I don't know why you think you'd get flak for adding some real-world experiences to the mix - out of interest what was the helicopter type you were flying?
Sounds like you invented the Vuichard technique before he did
Sounds like you invented the Vuichard technique before he did
Did a similar exercise at night using a Smoke Stack, NVG's, and FLIR.....hover at several assigned heights above the stack (using FLIR to peer down the inside of the Stack for position and RadAlt for height) and hold position for a minute or two until told to move up to the next height.
We were not told the reason for the Test Program.....as we did not have a need to know....as it was at a sensitive location.
I can only imagine how hard maintaining position using a laser must have been....as we had far more tolerance but far less accurate a measuring system.
Odd thing....we never experienced VRS.....unless only in the incipient stage. Light aircraft with ample surplus power margin and I always used a heading into the prevailing wind as that made the exercise very much less a chore.
Edit: Upon some reflection I recalled there were onsets of some loss of control....felt as sloppiness in being able to control Pitch and Yaw....always combined with a loss of height...but never an elevator ride kind of loss of height.....perhaps we were just powering out of it as we accelerated forward into cleaner airflow through the rotor system.
It was pretty much an Instruments only process with the added cross check of the FLIR Screen.
I am guessing our target was about a Three Foot Diameter hole at the top of the Stack.
The Boffins sure seem to have an uncanny ability to conjure up challenging tasks for us lesser beings to perform.
At times it allows you to empathize with a Lab Rat.
We were not told the reason for the Test Program.....as we did not have a need to know....as it was at a sensitive location.
I can only imagine how hard maintaining position using a laser must have been....as we had far more tolerance but far less accurate a measuring system.
Odd thing....we never experienced VRS.....unless only in the incipient stage. Light aircraft with ample surplus power margin and I always used a heading into the prevailing wind as that made the exercise very much less a chore.
Edit: Upon some reflection I recalled there were onsets of some loss of control....felt as sloppiness in being able to control Pitch and Yaw....always combined with a loss of height...but never an elevator ride kind of loss of height.....perhaps we were just powering out of it as we accelerated forward into cleaner airflow through the rotor system.
It was pretty much an Instruments only process with the added cross check of the FLIR Screen.
I am guessing our target was about a Three Foot Diameter hole at the top of the Stack.
The Boffins sure seem to have an uncanny ability to conjure up challenging tasks for us lesser beings to perform.
At times it allows you to empathize with a Lab Rat.
Last edited by SASless; 10th Apr 2022 at 17:52.
Originally Posted by [email protected]
I don't know why you think you'd get flak for adding some real-world experiences to the mix - out of interest what was the helicopter type you were flying?
Sounds like you invented the Vuichard technique before he did
Sounds like you invented the Vuichard technique before he did
Starting from 100 ASL to 8000 ASL Temps -20 to +25C. Terrain100 ASL to 1500-2000.
Well some folks are going to say that entering VRS in still air and zero rate of descent is impossible.
In discussion years later with a very experienced and well respected test pilot he was surprised to hear of it but thought that it was just amazing that the circumstance was created. The ‘Laser’ keeping the aircraft in a +- 24 inch hover for extended periods and the aircraft being tracked with a theodolite. The chance to operate in the conditions described and stay in VRS for up to 1-2 minutes try various things and observe results was a unique opportunity. He said that they had never even thought of doing it and it would have been a separate test programme during which it would have been difficult to achieve the test parameters.. I agreed totally with him. It was an interesting thing but not worth the candle to spend time to explore. In the end what would have been the benefit of it a except the “Been There Done That” T-shirt.
You always lost the ‘Laser’ dot when it happened so you had to descend back down to ground level so staying in VRS was quick way to get there. I found exiting at a +-45 degree from aircraft heading with a +- 10 degree nose down attitude to gain fwd speed seemed to work best. You could exit by entering autorotation but this involved a considerable height loss. Exiting fully developed VRS with power applied and fwd speed was the most easy but when you are looking at VS anywhere from -1500 to -2500 it is going to take TIME and ALTITUDE to return to straight and level flight. As I stated before aside from the sloppy controls the aircraft never entered any unusual attitude or did anything scary. It seemed happy in the state it was in, no RPM, Torque or heading changes.
Well some folks are going to say that entering VRS in still air and zero rate of descent is impossible.
I wonder if there was some convective updraught that brought your downwash closer?
It doesn't matter, you were there and experienced it repeatedly with time and height to experiment a bit.
Would it be fair to say you never got it out of VRS in 50' -100'?
I can imagine a light 350 doesn't produce a very powerful downwash - I've only flown the BB version.
Where is a really smoking engine when you need one. To see the airflow around that ship would have been fascinating.
How to get VRS without descending? Something I really like to try. But let's think about it. In a very light ship, one should be capable to pull more and more power to stay in place, but the tip vortices could in this condition grow and have the desired effect. After all, there is never no lift. Could that be what happened here?
How to get VRS without descending? Something I really like to try. But let's think about it. In a very light ship, one should be capable to pull more and more power to stay in place, but the tip vortices could in this condition grow and have the desired effect. After all, there is never no lift. Could that be what happened here?
Given the huge range of density altitudes that albatross has described there must have been some occasions when high pitch angles (for high DA) would have produced strong tip vortices and high AoA at the root - classic VRS conditions if you then start to descend.
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Here is a suggestion.
It is not only the tip vortices, but also the root stall that allows the vortex ring state.
The steady increase in DA would have increased the stalled area, perhaps to a critical state where there was not enough thrust to maintain height.
Once descent started, however small, there could be a flow up through the large stalled area of the rotor disc and VR was established.
Edit: Bah! Beaten to it by crab.
It is not only the tip vortices, but also the root stall that allows the vortex ring state.
The steady increase in DA would have increased the stalled area, perhaps to a critical state where there was not enough thrust to maintain height.
Once descent started, however small, there could be a flow up through the large stalled area of the rotor disc and VR was established.
Edit: Bah! Beaten to it by crab.
Where is a really smoking engine when you need one. To see the airflow around that ship would have been fascinating.
How to get VRS without descending? Something I really like to try. But let's think about it. In a very light ship, one should be capable to pull more and more power to stay in place, but the tip vortices could in this condition grow and have the desired effect. After all, there is never no lift. Could that be what happened here?
How to get VRS without descending? Something I really like to try. But let's think about it. In a very light ship, one should be capable to pull more and more power to stay in place, but the tip vortices could in this condition grow and have the desired effect. After all, there is never no lift. Could that be what happened here?
Some of the stuff formerly normally done in daze of yore are now seen as, reckless negligence, dangerous and foolhardy especially by Lawyers, their evil spawn, ilk, minions and sycophants
It would never occur if you maintained even a very slow rate of climb once the customer had you in sight, some guys always did that .Sometimes the customer asked you to hover or even descend “on the dot”. It would not happen in a steady state hover if there was any wind to speak of. In the case I speak of I recall the following conditions were present. 0 wind, hover maintained for at least a minute with probability increasing the longer you sat there, very steady air mass with no or very little thermal activity either upwards or downwards. You would sit there happily pulling perhaps a steady 80 to 85 torque. once you got that “little flicker” on the VSI application of power only accelerated the process. When it entered VRS, which was not violent in any way but very abrupt with the VSI going to -1000+FPM in seconds. if you didn’t do anything except pull more torque the aircraft would just fall faster in the exhilarating vertical descent. You had to initiate horizontal movement to fly out of the vortex. Having at least your former hover power applied as you exited the vortex certainly helped stop the rate of descent ASAP as you flew back into good clean air.
I am told that they don’t even demonstrate fully developed VRS anymore in training. Much as they only demonstrate incipient spins in fixed wing. One had to be signed off in olden daze for full spins in order to get a private fixed wing licence and would be required to demonstrate competency during your check-ride.
NB Remember that VRS is not Settling with Power and can occur at very low gross weight.
. ( Now referred to as Mass for reasons known onto Gawd. I would have liked to be a fly on the wall at the long series of committee meetings where that earth shattering decision was made. “Gentleman, we must appear to be doing important things while in actuality not doing anything. We’ve beaten both the constant ‘Rad Alt Setting Changes’ and ‘change the font on the checklists to improve efficiency’ to death so it’s time change something else. Last year’s forbidding use of “Roger, Wilco, Over, Standby-One, CAVU, WOXOFF ” and other clear, concise but archaic terms was brilliant. Changing ZULU time to GMT and then immediately to Co-ordinated Universal Time was a stroke of pure genius. Any new useful but useless suggestions?”)
Last edited by albatross; 10th Apr 2022 at 19:52.
I wish there was a "Like" button at pprune......some of these posts would certainly earn some Clicks.
Great stuff albatross
Just one more comment:
It is all fun and games discussing VRS here but:
After the debate of best practice for avoiding VRS, Recovering from incipient VRS and recovering from fully developed VRS.
It is imperative that you have a proper technique in your bag of tricks.
If you encounter VRS in any state there will be no time to have a debate with yourself as to what you should do before things go from bad to awful.
Have a plan in place, carry it out.
Even if you just suspect you are entering VRS recover to a safe flight regime immediately.( IE Forward speed, altitude level or climbing, Power and RPM in limits. )
Fly safe everyone.
It is all fun and games discussing VRS here but:
After the debate of best practice for avoiding VRS, Recovering from incipient VRS and recovering from fully developed VRS.
It is imperative that you have a proper technique in your bag of tricks.
If you encounter VRS in any state there will be no time to have a debate with yourself as to what you should do before things go from bad to awful.
Have a plan in place, carry it out.
Even if you just suspect you are entering VRS recover to a safe flight regime immediately.( IE Forward speed, altitude level or climbing, Power and RPM in limits. )
Fly safe everyone.
This section was drafted by him for NTPS, back when Nadia and Sean were still involved in the place. Was a good alternative to FTM-106 Ch 5. He maintained his enthusiasm throughout.
Well, Dan Gryder claims, and substantiates his claim in a recent YouTube video, that
- The latest (and several other before) VRS-related accidents are not caused by inadvertent entry into VRS but by people voluntarily going out to practise VRS recovery in flight.
- And that those people practising VRS recovery put themselves into full VRS, which directly or indirectly (eg, inappropriate control inputs) led to the accidents that he discusses (including the Miami Bell 429 EMS / training accident).
- That the high publicity around the Vuichard recovery technique (as promoted since 2017 in every Heli-Expo, also officially adopted by Robinson, and via Tim Tucker's efforts included in the FAA helicopter syllabus) and the premise that it is easy to use this technique to deal with incipient VRS, have triggered the wide-spread practising of VRS recovery across all areas of ab initio and recurrent training.
According to Dan Gryder, the NTSB misread a 2017 Bell 407 VRS accident, assuming that it was caused by inadvertent entry into VRS, whereby possibly the two pilots went out - only a few days after having attended Claude Vuichard's seminar at Heli-Expo 2017 - to practise VRS recovery in flight on their own.
Most importantly, the NTSB - believing that lack of training in dealing with VRS contributed to the accident - then proceeded to formally recommending more and frequent VRS recovery training across the board. In other words that the cure that the NTSB recommends (frequent VRS recovery training) in itself is the cause for the VRS-related accidents.
- The latest (and several other before) VRS-related accidents are not caused by inadvertent entry into VRS but by people voluntarily going out to practise VRS recovery in flight.
- And that those people practising VRS recovery put themselves into full VRS, which directly or indirectly (eg, inappropriate control inputs) led to the accidents that he discusses (including the Miami Bell 429 EMS / training accident).
- That the high publicity around the Vuichard recovery technique (as promoted since 2017 in every Heli-Expo, also officially adopted by Robinson, and via Tim Tucker's efforts included in the FAA helicopter syllabus) and the premise that it is easy to use this technique to deal with incipient VRS, have triggered the wide-spread practising of VRS recovery across all areas of ab initio and recurrent training.
According to Dan Gryder, the NTSB misread a 2017 Bell 407 VRS accident, assuming that it was caused by inadvertent entry into VRS, whereby possibly the two pilots went out - only a few days after having attended Claude Vuichard's seminar at Heli-Expo 2017 - to practise VRS recovery in flight on their own.
Most importantly, the NTSB - believing that lack of training in dealing with VRS contributed to the accident - then proceeded to formally recommending more and frequent VRS recovery training across the board. In other words that the cure that the NTSB recommends (frequent VRS recovery training) in itself is the cause for the VRS-related accidents.
At the beginning of the video, Dan Gryder mentions several times that he isn't a helicopter guy and that is blindingly obvious from the rest of the video. He equates settling with power to VRS - something I hope that has been made clear is that they are similar but separate situations that superficially look the same but have different causes.
His assertions that pilots may have been 'experimenting' with VRS recovery, post the fanfares about Vuichard technique, may or may not be valid.
I have said frequently that believing Vuichard will get you out of full VRS is likely to give pilots false confidence - if that false confidence leads to pilots flirting with full VRS instead of just recovering at the incipient stage then Mr Vuichard and Tim Tucker have a lot to answer for.
His assertions that pilots may have been 'experimenting' with VRS recovery, post the fanfares about Vuichard technique, may or may not be valid.
I have said frequently that believing Vuichard will get you out of full VRS is likely to give pilots false confidence - if that false confidence leads to pilots flirting with full VRS instead of just recovering at the incipient stage then Mr Vuichard and Tim Tucker have a lot to answer for.
Originally Posted by [email protected]
. He equates settling with power to VRS - something I hope that has been made clear is that they are similar but separate situations that superficially look the same but have different causes.
.
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If you know what country a guy is from, you'll know what he means by SWP
Originally Posted by [email protected]
I know what he means by SWP and it is the wrong terminology - even the FAA have caught up now.
,...and the FAA hasn't "caught up" they just gave up and removed the term SWP from the books. That thing you and Canada call SWP is still too ridiculous to be in our books. In the US (officially) the term SWP doesn't mean anything anymore.
Page 11-9Vortex Ring State
https://www.faa.gov/sites/faa.gov/fi...k/hfh_ch11.pdf
Vortex ring state (formerly referenced as settling-with- power) describes an aerodynamic condition in which a helicopter may be in a vertical descent with 20 percent up to maximum power applied, and little or no climb performance. The previously used term settling-with-power came from the fact that the helicopter keeps settling even though full engine power is applied.