AS350 Astar / AS355 Twinstar [Archive Copy]
"110 kts, straight and level, collective bottomed, 500 lbs below max gross, descent off the top of the mountain - wind sheer, a/s up to 155kts, a/c snapped to the right 90 degrees."
So you exceeded the max autorotation "collective bottomed" airspeed by 40 knots at sea level and it's a design flaw? Sounds to me like you put the aircraft far out of any reasonable design reserve.
So you exceeded the max autorotation "collective bottomed" airspeed by 40 knots at sea level and it's a design flaw? Sounds to me like you put the aircraft far out of any reasonable design reserve.
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First of all, I just copied that from another bulletin board - it wasn't me (read the post).
Secondly, it is a typical situation in the mountains, POH notwithstanding, and a 90 degree snap to the right is not what you want right then. It shouldn't be what you get at *any* time.
When senior test engineers or pilots admit that it was a bigger factor than originally catered for, I would suggest it is something that ought to be fixed, n'est-ce pas?
Phil
Secondly, it is a typical situation in the mountains, POH notwithstanding, and a 90 degree snap to the right is not what you want right then. It shouldn't be what you get at *any* time.
When senior test engineers or pilots admit that it was a bigger factor than originally catered for, I would suggest it is something that ought to be fixed, n'est-ce pas?
Phil
Avoid imitations
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Seems to me there are two polarised opinions here.
One from pilots who observe the published aircraft limitations and have no problems.
The other from people who think that limits are to be ignored when it suits them, suffer a fright as the consequence and then call it a design fault.
"Whaddya mean, stressed to 4G?
I've only been pulling 5G all morning and then the wing came off this afternoon!!
I think you're a crap designer!"
One from pilots who observe the published aircraft limitations and have no problems.
The other from people who think that limits are to be ignored when it suits them, suffer a fright as the consequence and then call it a design fault.
"Whaddya mean, stressed to 4G?
I've only been pulling 5G all morning and then the wing came off this afternoon!!
I think you're a crap designer!"
"First of all, I just copied that from another bulletin board - it wasn't me (read the post)."
Sorry about that. I thought you were re-posting something you had already posted.
"Secondly, it is a typical situation in the mountains, POH notwithstanding, and a 90 degree snap to the right is not what you want right then. It shouldn't be what you get at *any* time."
I'm not sure what mountains you fly in but where I fly the "V" limitations are exactly that. Anyone near gross weight that puts the pitch down, rolls the nose over and approaches an airspeed limitation, in anything but the smoothest air is asking for exactly what happened."
"When senior test engineers or pilots admit that it was a bigger factor than originally catered for, I would suggest it is something that ought to be fixed, n'est-ce pas?"
Who are these senior people that have all this Astar experience? Lu probably has never even riden in one. Lu knows lot about why helicopters fly but he knows little about how a helicopter flies. And Nick has already stated he does not have that much experience with the AS350/355 series. What I've been reading is that the pilots with considerable Astar experience are saying there is nothing wrong.
I haven't been fortunate enough to fly one of the new generation attack helicopters but every helicopter I have flown will exhibit "Jack Stall" if pushed past it's published limits. Which model do you consider immune?
Sorry about that. I thought you were re-posting something you had already posted.
"Secondly, it is a typical situation in the mountains, POH notwithstanding, and a 90 degree snap to the right is not what you want right then. It shouldn't be what you get at *any* time."
I'm not sure what mountains you fly in but where I fly the "V" limitations are exactly that. Anyone near gross weight that puts the pitch down, rolls the nose over and approaches an airspeed limitation, in anything but the smoothest air is asking for exactly what happened."
"When senior test engineers or pilots admit that it was a bigger factor than originally catered for, I would suggest it is something that ought to be fixed, n'est-ce pas?"
Who are these senior people that have all this Astar experience? Lu probably has never even riden in one. Lu knows lot about why helicopters fly but he knows little about how a helicopter flies. And Nick has already stated he does not have that much experience with the AS350/355 series. What I've been reading is that the pilots with considerable Astar experience are saying there is nothing wrong.
I haven't been fortunate enough to fly one of the new generation attack helicopters but every helicopter I have flown will exhibit "Jack Stall" if pushed past it's published limits. Which model do you consider immune?
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Lama Bear said:
I haven't been fortunate enough to fly one of the new generation attack helicopters but every helicopter I have flown will exhibit "Jack Stall" if pushed past it's published limits. Which model do you consider immune?
Nick sez:
The servo strength does not have to be infinate to counter the stall forces from the rotor, because the moment the blades generate reaches a practical limit in deep stall. Therefore, there is not a relationship between the designer building ever stronger servos to counter the pilot doing ever more aggressive maneuvers. A properly designed control system always wins against the blade stall forces.
In US Military service, the maneuvers must be tested to extreme limits in a structural demonstration where we squeeze everything out of the helicopter and make sure that controls, structure and systems all support the pilot. Jack stall is not allowed, and any helicopter that demonstrates it must be redesigned (usually by making the servos stronger).
In short, no Boeing, Sikorsky or Bell product of the last two generations has or can experience jack stall.
I haven't been fortunate enough to fly one of the new generation attack helicopters but every helicopter I have flown will exhibit "Jack Stall" if pushed past it's published limits. Which model do you consider immune?
Nick sez:
The servo strength does not have to be infinate to counter the stall forces from the rotor, because the moment the blades generate reaches a practical limit in deep stall. Therefore, there is not a relationship between the designer building ever stronger servos to counter the pilot doing ever more aggressive maneuvers. A properly designed control system always wins against the blade stall forces.
In US Military service, the maneuvers must be tested to extreme limits in a structural demonstration where we squeeze everything out of the helicopter and make sure that controls, structure and systems all support the pilot. Jack stall is not allowed, and any helicopter that demonstrates it must be redesigned (usually by making the servos stronger).
In short, no Boeing, Sikorsky or Bell product of the last two generations has or can experience jack stall.
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No, it's not something i already posted, but I had already alluded to the same thread a couple of messages ago - I thought you had read it, sorry 
It's just that I'm watching two threads at the same time on the same subject. In the other one (on www.canadianaviation.ca) there are a lot of experienced pilots giving examples of when they have encountered this phenomenon, which range from the relatively benign to the extreme, such as the last example I gave above. When I say "typical of the mountains", I meant the situation, where windshear will often take you a great deal above your target airspeed very quickly, obviously something to be watched for, but you can't always catch it.
Obviously, one shouldn't fly aircraft to their limits, and none is bulletproof, but my problem with this one is that it isn't repeatable under the same circumstances every time. If it were, you would just avoid it and regard it as a limitation, which it clearly isn't. I still maintain it should have been fixed as part of ongoing product development, while recognising that you can't design everything right first time.
Actually, Lu (or anyone else) wasn't on my mind when I posted - here is yet another quote from the other thread:
"Within the first 50 hrs of flight after my endorsement there I was with fire crew on board headed out for the old day base in Alberta - so very close to max. gross internal. 800' ceiling "zipping" down the siesmic line enroute to day base, spring black bear eating grass on siesmic line, fire fighter wants picture, tight right hand turn at about 110knts., rate of descent approximately 200-250fpm. you do the math on how long it is prior to controlled flight into terrain. Actually it would have been uncontrolled flight into terrain as I experience "servo transparency" - cyclic & collective FROZEN - the only controls left to help reconfigure the disc loading were the pedals - however I was unaware of what was happening and it was only #$%^house luck that I was able to regain control. If I had not the A/C plus 5 people would have been spread over the Alberta jackpine muskeg for a mile and no one would ever have come up with the reason.
It took me until 1997 for a eurocopter test pilot to admit to me in "private" that yes it was a bigger factor than had been anticipated. There are at least 3 fatal's I am aware of where it is my belief that "jack stall" was involved.
My advice - for what it is worth - enjoy the A/C but learn your product well, be careful of: subject discussed, vortex state ring, Hyd. failures and although a nimble and responsive A/c is should be flown more like a medium. If you have a penchant for being a cowboy - leave the boots and spurs at home on this one. This is not meant to frighten, however knowledge is one of the gateways to professionalism. Have a awesome season."
Phil
It's just that I'm watching two threads at the same time on the same subject. In the other one (on www.canadianaviation.ca) there are a lot of experienced pilots giving examples of when they have encountered this phenomenon, which range from the relatively benign to the extreme, such as the last example I gave above. When I say "typical of the mountains", I meant the situation, where windshear will often take you a great deal above your target airspeed very quickly, obviously something to be watched for, but you can't always catch it.
Obviously, one shouldn't fly aircraft to their limits, and none is bulletproof, but my problem with this one is that it isn't repeatable under the same circumstances every time. If it were, you would just avoid it and regard it as a limitation, which it clearly isn't. I still maintain it should have been fixed as part of ongoing product development, while recognising that you can't design everything right first time.
Actually, Lu (or anyone else) wasn't on my mind when I posted - here is yet another quote from the other thread:
"Within the first 50 hrs of flight after my endorsement there I was with fire crew on board headed out for the old day base in Alberta - so very close to max. gross internal. 800' ceiling "zipping" down the siesmic line enroute to day base, spring black bear eating grass on siesmic line, fire fighter wants picture, tight right hand turn at about 110knts., rate of descent approximately 200-250fpm. you do the math on how long it is prior to controlled flight into terrain. Actually it would have been uncontrolled flight into terrain as I experience "servo transparency" - cyclic & collective FROZEN - the only controls left to help reconfigure the disc loading were the pedals - however I was unaware of what was happening and it was only #$%^house luck that I was able to regain control. If I had not the A/C plus 5 people would have been spread over the Alberta jackpine muskeg for a mile and no one would ever have come up with the reason.
It took me until 1997 for a eurocopter test pilot to admit to me in "private" that yes it was a bigger factor than had been anticipated. There are at least 3 fatal's I am aware of where it is my belief that "jack stall" was involved.
My advice - for what it is worth - enjoy the A/C but learn your product well, be careful of: subject discussed, vortex state ring, Hyd. failures and although a nimble and responsive A/c is should be flown more like a medium. If you have a penchant for being a cowboy - leave the boots and spurs at home on this one. This is not meant to frighten, however knowledge is one of the gateways to professionalism. Have a awesome season."
Phil
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AS 355 CG Calculator (Excel)
Just polished up the spreadsheet I use for CG - if anyone else wants to use it or maybe improve on it, you can ftp it ftom here:
<a href="ftp://www.electrocution.com/pub/users/electroc/355cg.xls" target="_blank">ftp://www.electrocution.com/pub/users/electroc/355cg.xls</a>
It was done in Excel 2000, and may work elsewhere. The drop down buttons will not work in a Psion <img src="frown.gif" border="0"> . Working on the 206 one!
Cheers
phil
<a href="ftp://www.electrocution.com/pub/users/electroc/355cg.xls" target="_blank">ftp://www.electrocution.com/pub/users/electroc/355cg.xls</a>
It was done in Excel 2000, and may work elsewhere. The drop down buttons will not work in a Psion <img src="frown.gif" border="0"> . Working on the 206 one!
Cheers
phil
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Email me if you want an explanation of the formulae - we use a system of addendums to the original weighing report here, but the dropdown boxes could easily be used for separate aircraft.
Phil
PS forgot to mention - the top red dot on the graph is the takeoff CG, and the other one represents aafter two hours
[ 24 January 2002: Message edited by: paco ]</p>
Phil
PS forgot to mention - the top red dot on the graph is the takeoff CG, and the other one represents aafter two hours
[ 24 January 2002: Message edited by: paco ]</p>
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AS-350(Max Turbulence Speed)
My work mates and I have been discussing wether or not the AS350 has a "turbulance penetration speed". One of the guys we work with(ex Mil) says it does 
0kts which it clearly states in his Defence Force Flight Manual. But when we look for it in our civil flight manual there is no mention of it.. .I can't remember anything said about in my type rating(years ago). .So is there such a figure?. .Do the Mil guys know something we don't?. .or has Eurcopter just forgotten to add it?(which I dought)
. ."Wise man says 'make haste slowly that way accidents don't happen" <img src="rolleyes.gif" border="0">
0kts which it clearly states in his Defence Force Flight Manual. But when we look for it in our civil flight manual there is no mention of it.. .I can't remember anything said about in my type rating(years ago). .So is there such a figure?. .Do the Mil guys know something we don't?. .or has Eurcopter just forgotten to add it?(which I dought). ."Wise man says 'make haste slowly that way accidents don't happen" <img src="rolleyes.gif" border="0">
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Ive never seen it in a Squirrel flight manual either, 80 knots sounds right, its in my RAAF AS 350 pilots handbook. Perhaps it had to have a turbulence penetration speed for military acceptance.
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No, not yet, as I don't have access to the FM - if you could let me have the relevant details it shouldn't take long to work one up. Working on the 206 right now (with lat CG) and 76 next - just added a dropdown box to change fuel CG according to temperature.
phil
[ 26 January 2002: Message edited by: paco ]</p>
phil
[ 26 January 2002: Message edited by: paco ]</p>
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I just used a lot of IF statements allied to a code for the drop down box. The only problem is that Excel only allows 8, so if your company has more than that number in addendums, you have to create a kludge.
I've put all the essential elements in the top left corner, so all you need to do is set the print area and print for a hard copy.
What I want to do next is put in a calculation for Density Altitude and get a red line across the chart with a restricted takeoff weight (no particular reason, just for fun). This is relatively simple to do, were it not for the humidity element.
Would appreciate any "simple" calculations!
Cheers
Phil
[ 14 February 2002: Message edited by: paco ]</p>
I've put all the essential elements in the top left corner, so all you need to do is set the print area and print for a hard copy.
What I want to do next is put in a calculation for Density Altitude and get a red line across the chart with a restricted takeoff weight (no particular reason, just for fun). This is relatively simple to do, were it not for the humidity element.
Would appreciate any "simple" calculations!
Cheers
Phil
[ 14 February 2002: Message edited by: paco ]</p>
New AS 350 B2 Prices??
