Cross wind approach
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Cross wind approach
Greetings All,
I occasionally have to go in to a confined area site that would involve a steepish type of approach, my problem is that I can not approach with headings between 90’ and 225’ due to houses etc. So if the wind is from 315’ I would have to come in at a heading of 230’ish. Which is a 90’ cross wind.
My question is what airspeeds, ROD’s etc should I watch for to ensure a safe approach and also how appropriate is it to come to a high hover of about 100ft and then descent vertically (due to trees)
Thanks
Happy New Year.
Raven2
I occasionally have to go in to a confined area site that would involve a steepish type of approach, my problem is that I can not approach with headings between 90’ and 225’ due to houses etc. So if the wind is from 315’ I would have to come in at a heading of 230’ish. Which is a 90’ cross wind.
My question is what airspeeds, ROD’s etc should I watch for to ensure a safe approach and also how appropriate is it to come to a high hover of about 100ft and then descent vertically (due to trees)
Thanks
Happy New Year.
Raven2
Raven2
There's no problem with what you describe for private operations. You just need to be aware that you'll be putting yourself in the avoid area of the Heigh/Velocity chart. Furthermore, with a 90 x-wind, as you descend on the aproach, you'll notice that your IAS will show less than your real airspeed due to the apparent wind being off to the side.
This means two things;
1) if you tend to fly your approaches on the ASI you'll need to fly it faster to maintain the same 'indicated' airspeed which is not clever.
2) if you fly your approach visually using the apparent groundspeed (and I'd suggest an apparent gentle walking pace for such an approach), as you check your IAS on the approach you'll notice it reads zero very early on the approach which can shock the inexperienced/unwary into unnecessary overshoot action.
Therefore, my recommendation would be to set up your approach accurately from quite a long way out from known parameters; say 500ft agl and 50kts ( or 300ft agl and 30 kts). As you reach your descent point, forget the IAS but concentrate on maintaining the apparent groundspeed. Scan the VSI at regular intervals and be ready to overshoot if it starts to look like needing to exceed 500fpm to get in. Remember however, a helicopter which has ETL (Effective Translational Lift) cannot get into Vortex Ring so this 500fpm 'rule' isn't entirely necessary until later on the approach.
As regards the vertical descent; no problem. (You should have done this during your PPL(H) training). To judge the correct height, shoot your initial approach to just above the tree tops (10ft) on the near side of the Confined Area. As you reach this point, look ahead to the horizon and high-hover taxi forward until the centre of the CA (or until your tail is clear). From here, establish a high hover and gentle vertical descent to the ground. You can scan markers directly ahead of and to the side of the aircraft to ensure a vertical descent. (You could also yaw into wind before you start your descent to make handling easier).
Before you intend to try such an approach (and departure), get your head into the Flight Manual performance graphs and make sure you've got Hover Out of Ground Effect performance + 5%.
However, having said all of this, if you didn't complete this type of excercise during your training (and from your question, it sounds like you didn't), I'd recommend getting a refresher lesson from a suitably experienced FI before you try it on your own. It'll cost you a bit extra, but it'll be a whole lot cheaper than a main or tail rotor strike!
J
There's no problem with what you describe for private operations. You just need to be aware that you'll be putting yourself in the avoid area of the Heigh/Velocity chart. Furthermore, with a 90 x-wind, as you descend on the aproach, you'll notice that your IAS will show less than your real airspeed due to the apparent wind being off to the side.
This means two things;
1) if you tend to fly your approaches on the ASI you'll need to fly it faster to maintain the same 'indicated' airspeed which is not clever.
2) if you fly your approach visually using the apparent groundspeed (and I'd suggest an apparent gentle walking pace for such an approach), as you check your IAS on the approach you'll notice it reads zero very early on the approach which can shock the inexperienced/unwary into unnecessary overshoot action.
Therefore, my recommendation would be to set up your approach accurately from quite a long way out from known parameters; say 500ft agl and 50kts ( or 300ft agl and 30 kts). As you reach your descent point, forget the IAS but concentrate on maintaining the apparent groundspeed. Scan the VSI at regular intervals and be ready to overshoot if it starts to look like needing to exceed 500fpm to get in. Remember however, a helicopter which has ETL (Effective Translational Lift) cannot get into Vortex Ring so this 500fpm 'rule' isn't entirely necessary until later on the approach.
As regards the vertical descent; no problem. (You should have done this during your PPL(H) training). To judge the correct height, shoot your initial approach to just above the tree tops (10ft) on the near side of the Confined Area. As you reach this point, look ahead to the horizon and high-hover taxi forward until the centre of the CA (or until your tail is clear). From here, establish a high hover and gentle vertical descent to the ground. You can scan markers directly ahead of and to the side of the aircraft to ensure a vertical descent. (You could also yaw into wind before you start your descent to make handling easier).
Before you intend to try such an approach (and departure), get your head into the Flight Manual performance graphs and make sure you've got Hover Out of Ground Effect performance + 5%.
However, having said all of this, if you didn't complete this type of excercise during your training (and from your question, it sounds like you didn't), I'd recommend getting a refresher lesson from a suitably experienced FI before you try it on your own. It'll cost you a bit extra, but it'll be a whole lot cheaper than a main or tail rotor strike!
J
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Jellycopter
That was a useful refresher. However, I was under the impression that the HV avoid curve data only applied to take off?
I often go into the back of the carpark of a local pub. This has only one way in and out, as there are buildings on two sides and trees on the third. The only approach and exit path is over open ground which drops away very sharply from the back of the site - in fact the kids were sledging down it when I went in on Xmas Eve (no, I did get them moved first before anybody comments). I only normally go in there in no wind conditions, as you are often faced with either a downwind approach or a downwind departure. Being cautious, I don't really want either as it is a tight little site. However I have often mused about trying it if the wind is across the approach/exit path and the preceding comments are therefore very relevant.
Maybe I will get an experienced LH seat person to ride in with me sometime when the wind is across.
That was a useful refresher. However, I was under the impression that the HV avoid curve data only applied to take off?
I often go into the back of the carpark of a local pub. This has only one way in and out, as there are buildings on two sides and trees on the third. The only approach and exit path is over open ground which drops away very sharply from the back of the site - in fact the kids were sledging down it when I went in on Xmas Eve (no, I did get them moved first before anybody comments). I only normally go in there in no wind conditions, as you are often faced with either a downwind approach or a downwind departure. Being cautious, I don't really want either as it is a tight little site. However I have often mused about trying it if the wind is across the approach/exit path and the preceding comments are therefore very relevant.
Maybe I will get an experienced LH seat person to ride in with me sometime when the wind is across.
The "dead man's curve" involves HEIGHT and AIRSPEED. It doesn't matter what you are doing at the time (the helo doesn't care whether you are approaching to land, cruising or taking off).
IF you are at a height and an airspeed that is defined within your curve, and the engine stops, then ....BINGO
Provided your flight is private, you are perfectly entitled to fly cross wind to and from a site. I would suggest, however, that to maintain your mantle as a 'professional pilot', you know what to do when things go wrong 'out of wind'......
pleasant flying.........
IF you are at a height and an airspeed that is defined within your curve, and the engine stops, then ....BINGO
Provided your flight is private, you are perfectly entitled to fly cross wind to and from a site. I would suggest, however, that to maintain your mantle as a 'professional pilot', you know what to do when things go wrong 'out of wind'......
pleasant flying.........
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There can be some confusion with regards to th HV diagram. In the some helicopter handbooks they show the diagram with a recommended take-off profile and not a landing one.
Therefore pilots can be left thinking it only
applies during take off.
Therefore pilots can be left thinking it only
applies during take off.
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Someone like Shawn may be able to confirm this, but I believe that there could be a difference between approach or departure. During departure (high power and positive collective pitch) the rate of RRPM decay (post engine failure) will be greater than during arrival (lower power and collective pitch). For this reason, you are likely to be be in (somewhat) better shape during arrival than departure at the same height/airspeed combination. You will also be in better shape if the helicopter is light.
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AFAIK the H/V diagram is based on Take off power, to allow for the worst case scenario. Rrpm decay will be highest with an armful of collective. Also, it takes a fixed reaction time into account.
Hence, for descends, the dead man's curve will be smaller, but how much smaller has not been fomally established.
Hence, for descends, the dead man's curve will be smaller, but how much smaller has not been fomally established.
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RE: the H/V curve and T.O./appch
Take a Schweizer 300CB at 20kt airspeed, climbing through 400' at 500'/min. You are using 26"mp or about 160hp to keep the blades spinning. Now take the same 300CB and descend at 20kt, 500'/min. You'll be using about 20"mp, or well under 100hp to keep RRPM in the green.
Now imagine a power loss in each situation. Obviously the RRPM would drop more dramatically in the climb than in the descent. But it would also take longer for an autorotative state to develop from the 500'/min climb, so RRPM would take longer still to recover. Put another way, you'd be fairly comfortable entering a practice auto at 20kt, 400', 20"mp and descending. You'd certainly think twice about chopping the throttle at 400', 26", 20kt and climbing.
That being said, a hovering descent at 200'/min would require substantial power, not much less than a stationary hover, so you should definitely respect the H/V diagram for this type of operation.
Now imagine a power loss in each situation. Obviously the RRPM would drop more dramatically in the climb than in the descent. But it would also take longer for an autorotative state to develop from the 500'/min climb, so RRPM would take longer still to recover. Put another way, you'd be fairly comfortable entering a practice auto at 20kt, 400', 20"mp and descending. You'd certainly think twice about chopping the throttle at 400', 26", 20kt and climbing.
That being said, a hovering descent at 200'/min would require substantial power, not much less than a stationary hover, so you should definitely respect the H/V diagram for this type of operation.
"Just a pilot"
A couple more thoughts:
Approach speeds in this case should be predicated on aircraft performance (factor in A/C weights, too), pilot experience, terrain, entry and exit paths- lots of things that would make me loath to say 40, 50, 60, or any fixed rate of knots. Some aircraft are harder to slow down in a descent. Some require speed to keep emergency maneuver capability. Altitude or airspeed, keep as much of both until you can't anymore, and usually you can carry speed longer. Suggestion- try to keep best glide speed (at least) through the transition, down to 2-300 feet absolute altitude (approach initiation point), when you're on angle, to your high hover point for the vertical. 70 kts or so in a 350, 60 in 206, etc. You'll know you had too much speed if your approach descent requires big power reductions to keep on angle, or slips. Do it again, slower.
Don't restrict yourself to conventional airplane patterns. Circling transitions, at least down to the initiation point (2-300 feet AGL) are a good way of keeping the LZ in sight, being neighborly, keeping forced landing sites in range and controlling speed. If you have good LZ location, you can also zig-zag, dog leg, what ever, the transition. Do it over the best escape terrain, within performance limits and flying neighborly.
If you gotta do it crosswind, put the wind on the strong side, i.e. right side for French products, left for the rest of the world (unless you're in a Bell...). Easier to reject the approach.
As the man said, above ETL, you don't have much to sweat regards vortex ring. If your approach involves extreme descents/speeds, however- abort. Your plan is flawed somewhere.
If you have to zero airspeed and continue a descent, slow is the word and high is good to make the transition- until you have more experience as to the dangers and trades to minimise hazards.
Descending into a hole, limited escape options, is not the time to get impatient or careless. 200 fpm vertical descent, is safe, slow enough that location in the hole is manageable. From a 100 feet, it's only 30 seconds at that rate. Don't rush it.
This is all a process trading helo flexibility against risk. Survival first!
Approach speeds in this case should be predicated on aircraft performance (factor in A/C weights, too), pilot experience, terrain, entry and exit paths- lots of things that would make me loath to say 40, 50, 60, or any fixed rate of knots. Some aircraft are harder to slow down in a descent. Some require speed to keep emergency maneuver capability. Altitude or airspeed, keep as much of both until you can't anymore, and usually you can carry speed longer. Suggestion- try to keep best glide speed (at least) through the transition, down to 2-300 feet absolute altitude (approach initiation point), when you're on angle, to your high hover point for the vertical. 70 kts or so in a 350, 60 in 206, etc. You'll know you had too much speed if your approach descent requires big power reductions to keep on angle, or slips. Do it again, slower.
Don't restrict yourself to conventional airplane patterns. Circling transitions, at least down to the initiation point (2-300 feet AGL) are a good way of keeping the LZ in sight, being neighborly, keeping forced landing sites in range and controlling speed. If you have good LZ location, you can also zig-zag, dog leg, what ever, the transition. Do it over the best escape terrain, within performance limits and flying neighborly.
If you gotta do it crosswind, put the wind on the strong side, i.e. right side for French products, left for the rest of the world (unless you're in a Bell...). Easier to reject the approach.
As the man said, above ETL, you don't have much to sweat regards vortex ring. If your approach involves extreme descents/speeds, however- abort. Your plan is flawed somewhere.
If you have to zero airspeed and continue a descent, slow is the word and high is good to make the transition- until you have more experience as to the dangers and trades to minimise hazards.
Descending into a hole, limited escape options, is not the time to get impatient or careless. 200 fpm vertical descent, is safe, slow enough that location in the hole is manageable. From a 100 feet, it's only 30 seconds at that rate. Don't rush it.
This is all a process trading helo flexibility against risk. Survival first!
Raven- you don't say what height you need to maintain to clear the obstacles but you could try a shallow or level approach to a high hover and then a vertical descent. As your speed reduces in the latter stages of the approach, use a combination of pedal and cyclic to gradually yaw the aircraft onto an into wind heading whilst still maintaining the approach track - ie you end up sliding sideways into the into wind hover above your landing site. We use this technique a lot in the mountains where you must avoid the lee of ridges, pinnacles etc due to turbulence.
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Paco:
This is the kind of bullsh*t thing I hate to see on this board. "I can confirm..." Oh yeah? Who are you, dickweed? Did you write the AFM for every helicopter on the market? You can confirm, can you?
I give pilots a lot of credit...normally. But this kind of crap just frosts my cojones. It's like Shawn saying it. He's an authority, right? I mean, he's Mr. Big-Time Test-Pilot! If enough people say junk like that, some un- or poorly-trained pilot will stick it in the back of his mind. "Well, the H-V chart only applies on take-off. I know that because Paco and Shawn and S76Heavy told me so on PPRuNe!"
Me, I would go by what the manufacturer of my machine tells me. If they do not specify otherwise, I would conclude that the H-V chart applies everywhere, especially for pilots who's skill level falls short of a Shawn Coyle or, evidently, Paco (meaning guys like me). Intellectually I would know that light/low-power/descending is better than heavy/high-power/ascending, but I would not summarily disregard the chart merely because I was "landing" and assumed that I was therefore granted some sort of immunity. If you are deep in the shaded area at very low airspeed with a minimal descent rate and high power, the helicopter won't know if you are landing or not.
So guys, stop talking out of your asses and try being just a little professional (I know it's tough for some of you). In-the-shaded-area is in-the-shaded-area. We fly in it sometimes, yes. But we do not disregard it. Only a true fool would.
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I can confirm that the H/V curve is not valid for approaches, although you would be well advised to take note of it.
I give pilots a lot of credit...normally. But this kind of crap just frosts my cojones. It's like Shawn saying it. He's an authority, right? I mean, he's Mr. Big-Time Test-Pilot! If enough people say junk like that, some un- or poorly-trained pilot will stick it in the back of his mind. "Well, the H-V chart only applies on take-off. I know that because Paco and Shawn and S76Heavy told me so on PPRuNe!"
Me, I would go by what the manufacturer of my machine tells me. If they do not specify otherwise, I would conclude that the H-V chart applies everywhere, especially for pilots who's skill level falls short of a Shawn Coyle or, evidently, Paco (meaning guys like me). Intellectually I would know that light/low-power/descending is better than heavy/high-power/ascending, but I would not summarily disregard the chart merely because I was "landing" and assumed that I was therefore granted some sort of immunity. If you are deep in the shaded area at very low airspeed with a minimal descent rate and high power, the helicopter won't know if you are landing or not.
So guys, stop talking out of your asses and try being just a little professional (I know it's tough for some of you). In-the-shaded-area is in-the-shaded-area. We fly in it sometimes, yes. But we do not disregard it. Only a true fool would.
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A bit touchy, aren´t we? Feel better now?
I suppose that Darwins theory applies to flying, the stupid and downright silly will get themselves killed (as will sometimes the skilled but unlucky), the rest wil learn and live..for now.
No comment on this board, in the crewroom or elsewhere absolves any pilot from reading the manuals and understanding what the limits of his aircraft and as importantly, his personal limits are. Anybody dumb enough to ignore that will get himself into trouble.
That therefore does not mean that we should no longer discuss theories on this forum because it might not be so blatantly obvious to someone that to take anything as gospel might get him killed. But if it does, he has himself to blame. Because this is a forum for professional pilots and it is not meant to cater for the lowest denominator. The day it dumbs down and does, it will be a sad and empty place.
I suppose that Darwins theory applies to flying, the stupid and downright silly will get themselves killed (as will sometimes the skilled but unlucky), the rest wil learn and live..for now.
No comment on this board, in the crewroom or elsewhere absolves any pilot from reading the manuals and understanding what the limits of his aircraft and as importantly, his personal limits are. Anybody dumb enough to ignore that will get himself into trouble.
That therefore does not mean that we should no longer discuss theories on this forum because it might not be so blatantly obvious to someone that to take anything as gospel might get him killed. But if it does, he has himself to blame. Because this is a forum for professional pilots and it is not meant to cater for the lowest denominator. The day it dumbs down and does, it will be a sad and empty place.
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S76Heavy:
I have seen an attitude on this very board in which some people feel that *any* technique that involves a level of skill more advanced than that of a private pilot should not be discussed for fear that some low-time Robbie pilot will go out, try it and kill himself. So I am first in line to say that yes, every aspect of helicopter flying should be discussed here. Advocating such things as steep- or crosswind approaches is one thing. It is quite another to say patently absurd things like "The H-V curve does not apply on landing." There is where I have to call foul. If that makes me "touchy," so be it. It is not how I fly.
And I have been flying a long, long, long time in both rotary- and fixed-wing. I cannot say with certainty that I would have made it to this point if I took the attitude that I could just ignore various performance charts at my discretion- especially charts that offer such scant margin for error in the first place! Maybe some pilots can rely on their superior skill for their entire careers. Me, I'm not that good and I don't even pretend that I am.
I also know that while the H-V chart does not reside in the "Limitations" section (with those rare exceptions), it does not mean that I might as well yank it from the manual and toss it out the window. And I really take offense at those who suggest otherwise. Like I said, if that makes me touchy, I can live with that.
No comment on this board, in the crewroom or elsewhere absolves any pilot from reading the manuals and understanding what the limits of his aircraft and as importantly, his personal limits are. Anybody dumb enough to ignore that will get himself into trouble.
That therefore does not mean that we should no longer discuss theories on this forum because it might not be so blatantly obvious to someone that to take anything as gospel might get him killed. But if it does, he has himself to blame. Because this is a forum for professional pilots and it is not meant to cater for the lowest denominator. The day it dumbs down and does, it will be a sad and empty place.
That therefore does not mean that we should no longer discuss theories on this forum because it might not be so blatantly obvious to someone that to take anything as gospel might get him killed. But if it does, he has himself to blame. Because this is a forum for professional pilots and it is not meant to cater for the lowest denominator. The day it dumbs down and does, it will be a sad and empty place.
And I have been flying a long, long, long time in both rotary- and fixed-wing. I cannot say with certainty that I would have made it to this point if I took the attitude that I could just ignore various performance charts at my discretion- especially charts that offer such scant margin for error in the first place! Maybe some pilots can rely on their superior skill for their entire careers. Me, I'm not that good and I don't even pretend that I am.
I also know that while the H-V chart does not reside in the "Limitations" section (with those rare exceptions), it does not mean that I might as well yank it from the manual and toss it out the window. And I really take offense at those who suggest otherwise. Like I said, if that makes me touchy, I can live with that.
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Cross/Out of wind approaches
This post has been an interesting read but a little perplexing to see such differences of opinion on a manuvore that ought to be fairly uniform in technique irrespective of aircraft (rotory-single engine in particular) type.
However, I have a questions drawn from the above posts.
Devil 49 said:
"If you gotta do it crosswind, put the wind on the strong side, i.e. right side for French products, left for the rest of the world (unless you're in a Bell...). Easier to reject the approach".
I fly an old underpowered machine, so wind speed and direction, fuel load, passenger weight, ambiant temperature, etc. are always carefully considered before a departure and approach. My machine is British built so the rotors turn the "French" way, clockwise when viewed from above. Therefore, with regard to the above comment, I would keep the wind on my left side, not right, so if things didn't go as planned and I found the throttle on the stop with the Rrpm decaying, I would turn 90 degrees left into wind and in doing so would off-load the tail providing additional power to the main rotor. Does this make sense, or have I miss understood something crucial?
jellycopter said:
"1) if you tend to fly your approaches on the ASI you'll need to fly it faster to maintain the same 'indicated' airspeed which is not clever.
2) if you fly your approach visually using the apparent groundspeed (and I'd suggest an apparent gentle walking pace for such an approach), as you check your IAS on the approach you'll notice it reads zero very early on the approach which can shock the inexperienced/unwary into unnecessary overshoot action".
I was always taught when carring out downwind/crosswind approaches to maintain a positive airspeed (anything will do but if you can keep 20kts. that's great) until the point that you pedal the helicopter round into wind and a hover, again, if it is possible to pedal it in the direction that off-loads the tail you benifit in power gain additional to the power gain from lowering the lever to prevent climbing as you come round into wind.
However, I have a questions drawn from the above posts.
Devil 49 said:
"If you gotta do it crosswind, put the wind on the strong side, i.e. right side for French products, left for the rest of the world (unless you're in a Bell...). Easier to reject the approach".
I fly an old underpowered machine, so wind speed and direction, fuel load, passenger weight, ambiant temperature, etc. are always carefully considered before a departure and approach. My machine is British built so the rotors turn the "French" way, clockwise when viewed from above. Therefore, with regard to the above comment, I would keep the wind on my left side, not right, so if things didn't go as planned and I found the throttle on the stop with the Rrpm decaying, I would turn 90 degrees left into wind and in doing so would off-load the tail providing additional power to the main rotor. Does this make sense, or have I miss understood something crucial?
jellycopter said:
"1) if you tend to fly your approaches on the ASI you'll need to fly it faster to maintain the same 'indicated' airspeed which is not clever.
2) if you fly your approach visually using the apparent groundspeed (and I'd suggest an apparent gentle walking pace for such an approach), as you check your IAS on the approach you'll notice it reads zero very early on the approach which can shock the inexperienced/unwary into unnecessary overshoot action".
I was always taught when carring out downwind/crosswind approaches to maintain a positive airspeed (anything will do but if you can keep 20kts. that's great) until the point that you pedal the helicopter round into wind and a hover, again, if it is possible to pedal it in the direction that off-loads the tail you benifit in power gain additional to the power gain from lowering the lever to prevent climbing as you come round into wind.
Skeeter,
You make some valuable comments and I too employ similar techniques when flying my very under-powered Rotorway Exec.
Regarding the option of maintaining IAS however, it can cause some confusion to inexperienced pilots who do not consider that the ASI under-reads significantly when the wind is not 'blowing' down the pitot from dead ahead. This gives the helicopter a significantly higher groundspeed than desired for such an approach. This inturn gives our inexperienced pilot a harder task at the bottom than it would if the groundspeed was carefully controlled from the top of drop.
Notwithstanding any of this, my original post was aimed at Raven2 whom I beleive to be less experienced due to the nature of his question. Furthermore, based on his 'name', Raven2, I'd assumed he was flying an R44 Raven 2 and therefore tailored my answer to fit the aircraft type he'd be flying.
Cheers,
J
You make some valuable comments and I too employ similar techniques when flying my very under-powered Rotorway Exec.
Regarding the option of maintaining IAS however, it can cause some confusion to inexperienced pilots who do not consider that the ASI under-reads significantly when the wind is not 'blowing' down the pitot from dead ahead. This gives the helicopter a significantly higher groundspeed than desired for such an approach. This inturn gives our inexperienced pilot a harder task at the bottom than it would if the groundspeed was carefully controlled from the top of drop.
Notwithstanding any of this, my original post was aimed at Raven2 whom I beleive to be less experienced due to the nature of his question. Furthermore, based on his 'name', Raven2, I'd assumed he was flying an R44 Raven 2 and therefore tailored my answer to fit the aircraft type he'd be flying.
Cheers,
J
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To Rotordog:
No problems with your opinion, I just think you could have chosen a more moderate way of expressing it, hence the "touchy" comment.
Discussing the H-V diagram means to me having it clear what entry position the manufactor used to determine the diagram. All helicopters I've flown had it stated that the diagram was based on a T/O power setting with a fixed delayed reaction time.
It's merely about getting the definitions right before the discusion.
To Skeeterpilot:
having the wind on the strong side is to ensure full T/R authority, but since you fly an underpowered machine, every technique is a trade off.
No problems with your opinion, I just think you could have chosen a more moderate way of expressing it, hence the "touchy" comment.
Discussing the H-V diagram means to me having it clear what entry position the manufactor used to determine the diagram. All helicopters I've flown had it stated that the diagram was based on a T/O power setting with a fixed delayed reaction time.
It's merely about getting the definitions right before the discusion.
To Skeeterpilot:
having the wind on the strong side is to ensure full T/R authority, but since you fly an underpowered machine, every technique is a trade off.
Skeeter - the idea behind flying with a right crosswind on your machine is that you are flying with less power pedal (and therefore less power) than if the wind is from the other side.
We know the fuselage wants to weathercock into wind and pedal is required to hold it out of wind - in your aircraft the right pedal required to combat a left crosswind would mean you would reach your power limit sooner than if you were using left pedal to combat a right crosswind.
I think holding 20 kts IAS on a downwind approach until you pedal it round in the hover is going to be very, very exciting. The whole point of a downwind approach is that you end up with a negative airspeed as you reduce groundspeed towards the hover.
We know the fuselage wants to weathercock into wind and pedal is required to hold it out of wind - in your aircraft the right pedal required to combat a left crosswind would mean you would reach your power limit sooner than if you were using left pedal to combat a right crosswind.
I think holding 20 kts IAS on a downwind approach until you pedal it round in the hover is going to be very, very exciting. The whole point of a downwind approach is that you end up with a negative airspeed as you reduce groundspeed towards the hover.
rotordog. You really should check your facts before commiting yourself to a crap comment. HV curves ARE based on max power at max AUM. Which means that if you are in the descent and at less than MAUM your chances are better than the HV curve would indicate. There is still one, of course, but it shrinks as amount of collective applied and mass reduces. So, it is worst case. Why else do we (or some of us) teach approaches which would appear to put us in the avoid curve?