AS350 Astar/Squirrel
I like that screwing definition too!!
3top, good demo. We use it often with the UH-1H during stuck left pedal forward situations.
But please note that you are describing LTA, not LTE when you use that demo to illustrate a point.
3top, good demo. We use it often with the UH-1H during stuck left pedal forward situations.
But please note that you are describing LTA, not LTE when you use that demo to illustrate a point.
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In the EC130 and as well in the new production AS350B3's, there is a potentiometer which monitors yaw movements which will increase the RRPM (thru the fadec) when T/R limits are being reached (when the 10% control margin is getting close). It is increased to something like 402 from 394 for the purpose of providing more T/R authority at those critical times, such as lifting heavy loads in the hover at altitude. Density altitude is also factored into the equation.
To me this supports Nick's comments that overpitching at altitude likely could lead to reaching or exceeding the 10% control margin for the 350's and thus insifficient T/R thrust.
To me this supports Nick's comments that overpitching at altitude likely could lead to reaching or exceeding the 10% control margin for the 350's and thus insifficient T/R thrust.
Interesting idea, squirrel. There must have been some decision making required in the design of it, for example, does it still act if an overtorque, say, would be needed to increase the Nr by the required amount?
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Squirrel and Arm,
The use of the governor to help controllability is a great idea, much in keeping with the idea that the total machine should respond to the mission.
I have personally worked three similar ideas into production, and on them, the overtorque issue was built into the logic, so that the uptrim of Nr was slowed down to match the torque limits available. For those who are wondering what we are talking about, the upbeep of Nr causes a torque increase, so that an overtorque is possible if something is not done to prevent it.
The three areas that I worked on were the Comanche load factor enhancement, where the main rotor is sped up if the aircraft is maneuvered so that stall is prevented, and controllability/maneuverability is enhanced. Another is the use of Nr to trim the best range solution, automatically. The third is the "blow away" limiter on the 76C+ and S-92, where the torque limiter is varied as the rpm droops, so that constant power is available, thus preventing the spiral decay that occurs when a dumb constant torque limit is imposed on the aircraft. If the helo has a constant torque limiter, any hover overtorque is liable to result ina ground contact as power is being reduced by the limiter. Because torque times rpm is power, if the torque is limited and rotor rpm decays, the power is being reduced, so the helo starts a descent, making the pilot pull more collective so that the rpm decays further, and so on, until the ground comes up and smites the helo.
I would bet that the EC people worked the overtorque issue into the logic, perhaps with a slow uptrim rate, or even a limiter to prevent overtorque.
The use of the governor to help controllability is a great idea, much in keeping with the idea that the total machine should respond to the mission.
I have personally worked three similar ideas into production, and on them, the overtorque issue was built into the logic, so that the uptrim of Nr was slowed down to match the torque limits available. For those who are wondering what we are talking about, the upbeep of Nr causes a torque increase, so that an overtorque is possible if something is not done to prevent it.
The three areas that I worked on were the Comanche load factor enhancement, where the main rotor is sped up if the aircraft is maneuvered so that stall is prevented, and controllability/maneuverability is enhanced. Another is the use of Nr to trim the best range solution, automatically. The third is the "blow away" limiter on the 76C+ and S-92, where the torque limiter is varied as the rpm droops, so that constant power is available, thus preventing the spiral decay that occurs when a dumb constant torque limit is imposed on the aircraft. If the helo has a constant torque limiter, any hover overtorque is liable to result ina ground contact as power is being reduced by the limiter. Because torque times rpm is power, if the torque is limited and rotor rpm decays, the power is being reduced, so the helo starts a descent, making the pilot pull more collective so that the rpm decays further, and so on, until the ground comes up and smites the helo.
I would bet that the EC people worked the overtorque issue into the logic, perhaps with a slow uptrim rate, or even a limiter to prevent overtorque.
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Helmet Fire,
of course you a right!
There is no LTE on a Robinson, well maybe at 60% MRRPM.
At some extreme flying (filming - sideways, etc....) I do run out of pedal, but there is never any loss of TR-power anywhere.
It is fun when one goes sideways (anywhere from 100š to 30š),
once you are all up on power and run out of pedal, you reduce power just a smidgen and the helo has TR again!
I can control the angle at full pedal just by changing the speed a little, playing with the collective just so little...
Okay to the TR-demo, PLEASE don't do this to your students or yourself!! It was a factory designed demo to show the great power of the Robinson TR and I think part of it (as a side benefit) to demo the helo won't come falling as a rock just because the low rpm warning starts to yell....
I use 85% at 1 foot hover, light load, If I have to do recurrency training with oldtimers that HAD to change to the R brand - especially if they come screaming down at 110% - 2000' VS in an auto, because of "fear of death by low RRPM!"
I was in a R-22 when it was shown to me (80%RRPM), and I observed it done at 75% in a R-44.
The blades start to cone at an obscene angle!!
Thanks to the coning hinges the stay pretty much straight though!
3top
of course you a right!
There is no LTE on a Robinson, well maybe at 60% MRRPM.
At some extreme flying (filming - sideways, etc....) I do run out of pedal, but there is never any loss of TR-power anywhere.
It is fun when one goes sideways (anywhere from 100š to 30š),
once you are all up on power and run out of pedal, you reduce power just a smidgen and the helo has TR again!
I can control the angle at full pedal just by changing the speed a little, playing with the collective just so little...
Okay to the TR-demo, PLEASE don't do this to your students or yourself!! It was a factory designed demo to show the great power of the Robinson TR and I think part of it (as a side benefit) to demo the helo won't come falling as a rock just because the low rpm warning starts to yell....
I use 85% at 1 foot hover, light load, If I have to do recurrency training with oldtimers that HAD to change to the R brand - especially if they come screaming down at 110% - 2000' VS in an auto, because of "fear of death by low RRPM!"
I was in a R-22 when it was shown to me (80%RRPM), and I observed it done at 75% in a R-44.
The blades start to cone at an obscene angle!!
Thanks to the coning hinges the stay pretty much straight though!
3top
Thanks, Nick. Sounds like some great ideas for making use of newer technology to take the load off the pilot and make things generally more safe and efficient.
Nick,
pity you didn't work for Bell; they could have used some of that logic themselves (along with the "let's save the MGB rather than the airframe" logic!)
pity you didn't work for Bell; they could have used some of that logic themselves (along with the "let's save the MGB rather than the airframe" logic!)
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212man,
No pity here, Bell uses a different philosophy with everything, consistent with holding down the lower cost end of the market (that is not a slur, someone has to fill that market slice!)
The S-58T had the simple torque limiter, it was once all we had. New integre=ated systems allow us to mix variables from all over the aircraft, making it far easier to tailor the behavior more precisely to the need. Ofter, the trick is to think of what the pilot now does, and do that, automatically.
No pity here, Bell uses a different philosophy with everything, consistent with holding down the lower cost end of the market (that is not a slur, someone has to fill that market slice!)
The S-58T had the simple torque limiter, it was once all we had. New integre=ated systems allow us to mix variables from all over the aircraft, making it far easier to tailor the behavior more precisely to the need. Ofter, the trick is to think of what the pilot now does, and do that, automatically.
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All I know is that in the normal Bell 206 L4, if you are not careful about your weight, and you try to take off into a hover too heavy at a high DA, you will find yourself spinning as soon as the skids leave the ground with the pedal all the way to stop, and with about only 80% power applied (TQ), bringing it down again becomes very tricky, if you try to do anything but roll the throttle off.
There is a beautiful video of this, pilot who is taking off from high mountain, starts spininng a foot off the ground, doesn't have TR authority, but has enough power to climb vertically (while spinning of course) then he dives it, recovers control for an instant at about 50 feet, only to loose it again and crash.
Don't know if you can call that LTE, LTA but whatever it is its a very dangerous if you are not careful.
The 407 TR, well that is a completely different story, it will get you out of most trouble, but it will also reach it's limits at altitude if you are not careful.
There is a beautiful video of this, pilot who is taking off from high mountain, starts spininng a foot off the ground, doesn't have TR authority, but has enough power to climb vertically (while spinning of course) then he dives it, recovers control for an instant at about 50 feet, only to loose it again and crash.
Don't know if you can call that LTE, LTA but whatever it is its a very dangerous if you are not careful.
The 407 TR, well that is a completely different story, it will get you out of most trouble, but it will also reach it's limits at altitude if you are not careful.
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Hi all,
Nick said:"No pity here, Bell uses a different philosophy with everything, consistent with holding down the lower cost end of the market (that is not a slur, someone has to fill that market slice!)"
Well Bell is not THAT cheap anymore either:
Someone local just bought a 206BIII with some minimum equipment for US$1.2 M, delivered in 2008!!
You get THREE R-44-II models for that and fly 9pax to more altitude than the good old 206, NEVER worry about the TR, now you even can get a A/C, delivery in 4-5 month....
And no I am NOT a Robinson Dealer or get any credits from Frank!
I love EC though!
3top
Nick said:"No pity here, Bell uses a different philosophy with everything, consistent with holding down the lower cost end of the market (that is not a slur, someone has to fill that market slice!)"
Well Bell is not THAT cheap anymore either:
Someone local just bought a 206BIII with some minimum equipment for US$1.2 M, delivered in 2008!!
You get THREE R-44-II models for that and fly 9pax to more altitude than the good old 206, NEVER worry about the TR, now you even can get a A/C, delivery in 4-5 month....
And no I am NOT a Robinson Dealer or get any credits from Frank!
I love EC though!
3top
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In Bell's defence (or is it defense???) - the Bell 430 had suffienct tail rotor authority at the worst condition of wind at maximum weight at 7,000' Density altitude. (I did some flight testing with them when I was at Transport Canada).
And there is limit to what you can do with the tail rotor - put in such a big tail rotor that it really eats into payload.
There is, for example, no requirement in the regulations to be able to maintain heading while climbing vertically at maximum torque - should this be a requirement? Or should it be to maintain heading with winds up to 30 knots? or 20 mph as it currently is?
and Nick - I think you'd be surprised how many helicopter pilots never look at performance charts!
And there is limit to what you can do with the tail rotor - put in such a big tail rotor that it really eats into payload.
There is, for example, no requirement in the regulations to be able to maintain heading while climbing vertically at maximum torque - should this be a requirement? Or should it be to maintain heading with winds up to 30 knots? or 20 mph as it currently is?
and Nick - I think you'd be surprised how many helicopter pilots never look at performance charts!
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Shawn,
Actually, the 430 has twin sets of WAT curves, one set ( a pair of IGE and OGE hover charts) allows "wind from any azimuth" and the other set shows gross weights about 500 lbs more, and is for "wind within 45 degrees of the nose" for Cat B, 9 passengers or less.
This same travesty is published for the 212 and 412. I discussed this with the Ft. Worth ACO, and he told me that the zero margin yaw condition was used in the higher WAT because it was demonstrated and was safe, even though momentary contact with the stops was made, as long as there was measurable yaw rate in the direction of the input, there was still "control". Look at 29-2C page B-102 for a (ghastly) explanation of it.
See page 27 of the 430 product spec for the double line, one allowing hover with the wind off the nose only. I can email it to you, if you wish. Using this chart, the pilot can offload 600 lbs and have a good tail rotor, or gain the 600 lbs and lose yaw authority to fight a crosswind.
I have faced Bell 412's being sold to Saudi Arabia as SAR aircraft where that higher gross weight chart was used, with the words xeroxed out.
Actually, the 430 has twin sets of WAT curves, one set ( a pair of IGE and OGE hover charts) allows "wind from any azimuth" and the other set shows gross weights about 500 lbs more, and is for "wind within 45 degrees of the nose" for Cat B, 9 passengers or less.
This same travesty is published for the 212 and 412. I discussed this with the Ft. Worth ACO, and he told me that the zero margin yaw condition was used in the higher WAT because it was demonstrated and was safe, even though momentary contact with the stops was made, as long as there was measurable yaw rate in the direction of the input, there was still "control". Look at 29-2C page B-102 for a (ghastly) explanation of it.
See page 27 of the 430 product spec for the double line, one allowing hover with the wind off the nose only. I can email it to you, if you wish. Using this chart, the pilot can offload 600 lbs and have a good tail rotor, or gain the 600 lbs and lose yaw authority to fight a crosswind.
I have faced Bell 412's being sold to Saudi Arabia as SAR aircraft where that higher gross weight chart was used, with the words xeroxed out.
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AS 350 Operating costs
Trying to find information on operating costs and lease costs for an A-Star.
Not getting a lot of joy from net trawling - can someone please point me in the right direction. Approximate numbers are absolutely fine.
Thanks
Geoff
Not getting a lot of joy from net trawling - can someone please point me in the right direction. Approximate numbers are absolutely fine.
Thanks
Geoff
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http://www.aso.com/i.aso3/staticcont...ain&iaso3sid=1
For 49.95 usd you get the single report.
if you have 515 USD you can get the complete database on CD.
http://www.gov.state.ak.us/omb/03OMB.../proj35930.pdf
above source cites 495 USD per hour.
For 49.95 usd you get the single report.
if you have 515 USD you can get the complete database on CD.
http://www.gov.state.ak.us/omb/03OMB.../proj35930.pdf
above source cites 495 USD per hour.
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Really depends on the model.
The B2 and B3 are way more expensive to operate than the BA. Figure a new 1d1 with all the trimmings is over 400k
A super D is a BA converted with a Lycoming Lts101. Better than a BA no where near a B2. advantage is the Lycoming is extrememly cheap to run, parts and support are in abundance. There is a new LTS101 conversion just certifed, that makes it a super B2, or something. Eagle in Spokane did a bunch of the flight testing on it for the feds. I hear it is a heck of alifter.
Why dont you call Eurocopter. I am sure they can give you the DOC's.
rb
The B2 and B3 are way more expensive to operate than the BA. Figure a new 1d1 with all the trimmings is over 400k
A super D is a BA converted with a Lycoming Lts101. Better than a BA no where near a B2. advantage is the Lycoming is extrememly cheap to run, parts and support are in abundance. There is a new LTS101 conversion just certifed, that makes it a super B2, or something. Eagle in Spokane did a bunch of the flight testing on it for the feds. I hear it is a heck of alifter.
Why dont you call Eurocopter. I am sure they can give you the DOC's.
rb