Sloppy feel in cyclic
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All this talk about worn controls and AFCS ?
It's a hyperthetical question to do with the effect of Nr droop on MR control and lift....doesn't have to be a Lynx...it's general helicopter aerodynamics. The situation is set whilst doing a max cont check because the aircraft then has high forward speed with relatively high pitch on the blades.
It's a hyperthetical question to do with the effect of Nr droop on MR control and lift....doesn't have to be a Lynx...it's general helicopter aerodynamics. The situation is set whilst doing a max cont check because the aircraft then has high forward speed with relatively high pitch on the blades.
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" The synerio i was given"
And you are doing a degree? I don't know why, but this seems a little suspicious to me.....is it because people are too lazy to bother checking their speelling before posting, or are so many people barely literate these days?
What degree are you doing Ronnie Barker? Sounds like an interesting one!
Happy New year to you all by the way, and good luck in 2010 in all you do.
And you are doing a degree? I don't know why, but this seems a little suspicious to me.....is it because people are too lazy to bother checking their speelling before posting, or are so many people barely literate these days?
What degree are you doing Ronnie Barker? Sounds like an interesting one!
Happy New year to you all by the way, and good luck in 2010 in all you do.
It is all but impossible to get a Lynx with CMRB (BERP Blades) into retreating blade stall - it does 160 kts with ease (212kts max speed record) and shrugs off high G manoeuvering with barely a wobble (2.7 G max permitted for aerobatic manoeuvres but it takes 3 with no problems).
The stick feel/trim can be turned off and leaves you with a heavy, pendulous feeling cyclic (like waving a broomstick with a weight on the bottom)but you still have one of the worlds most responsive helicopters on the other end of it.
96% Nr is not enough to cause the hyds to stop producing enough power but it might trip the gennies off leaving you with no stab. 96% Nr is also not low enough to cause any handling problems in terms of RBS - the flyaway manouvre from the ODM recommends drooping the Nr to below that if memory serves. ISTR the critical Nr for Lynx was about 85%, below which it was very difficult to recover it in flight.
Ronnie - I think you need to check who has asked this question and what Lynx knowledge they have - it may be that they have used a generic helicopter aerodynamics question and applied it to the Lynx without really knowing what the aircraft can do.
The stick feel/trim can be turned off and leaves you with a heavy, pendulous feeling cyclic (like waving a broomstick with a weight on the bottom)but you still have one of the worlds most responsive helicopters on the other end of it.
96% Nr is not enough to cause the hyds to stop producing enough power but it might trip the gennies off leaving you with no stab. 96% Nr is also not low enough to cause any handling problems in terms of RBS - the flyaway manouvre from the ODM recommends drooping the Nr to below that if memory serves. ISTR the critical Nr for Lynx was about 85%, below which it was very difficult to recover it in flight.
Ronnie - I think you need to check who has asked this question and what Lynx knowledge they have - it may be that they have used a generic helicopter aerodynamics question and applied it to the Lynx without really knowing what the aircraft can do.
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it may be that they have used a generic helicopter aerodynamics question and applied it to the Lynx
All of Ronnie's posts have refered to Army aircraft...Apache, Gazelle, Lynx. The course is obviously military orientated and so it makes sense that it focuses on aircraft types that the students can relate to.....shame about the inaccuracy to type performance though when choosing an a/c for a question.
The answer to the subject of this thread is retreating blade stall, nethertheless........the scenario gives high forward speed, high(ish) altitude and Nr droop, which are all contributing factors to this condition.
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My guess:
High ROD at normal airspeed (90 - 120 Kts) and heavy aft cyclic will cause this effect. Basically RBS! The cyclic goes 'sloppy' unless one reduces the back pressure AND reduces the collective pitch. A classic situation following a wing over. Not too many Lynx pilots will have experienced it unless they have been Display pilots or......... show-offs. (the same?). Excessive 'G' particulally during a 'pull-up' will have the same effect. NON BERP.
High ROD at normal airspeed (90 - 120 Kts) and heavy aft cyclic will cause this effect. Basically RBS! The cyclic goes 'sloppy' unless one reduces the back pressure AND reduces the collective pitch. A classic situation following a wing over. Not too many Lynx pilots will have experienced it unless they have been Display pilots or......... show-offs. (the same?). Excessive 'G' particulally during a 'pull-up' will have the same effect. NON BERP.
Twinhueyman - no.
FLI - all UK Lynx are BERP now and RBS most certainly isn't a factor even at max chat at max AUM. Loops take 2 -2.5G and steep turns at 60 deg are a 2 G manoeuvre and flown regularly during training. Even in a harsh recovery from a descent in a steep turn there is no hint of RBS and 140 kt rapid descents using 30 deg nose down are halted easily, again without any hint of RBS. Even at 10,000 DA with the aircraft full of freefallers ready to jump there is no sloppiness whatsoever in the cyclic.
It would take a massive Nr droop to cause any appreciable change in handling qualities because there is so much control power available - an effective hinge offset of 17% if memory serves.
FLI - all UK Lynx are BERP now and RBS most certainly isn't a factor even at max chat at max AUM. Loops take 2 -2.5G and steep turns at 60 deg are a 2 G manoeuvre and flown regularly during training. Even in a harsh recovery from a descent in a steep turn there is no hint of RBS and 140 kt rapid descents using 30 deg nose down are halted easily, again without any hint of RBS. Even at 10,000 DA with the aircraft full of freefallers ready to jump there is no sloppiness whatsoever in the cyclic.
It would take a massive Nr droop to cause any appreciable change in handling qualities because there is so much control power available - an effective hinge offset of 17% if memory serves.
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Spider mechanism wear?
Don't think this has come up yet:
How is the pitch link control spider spherical bush and slider mechanism lubricated? If greased i imagine wear will occur, as with any bush. Play might be the first indication of this wear, as i imagine difficult access would make this hard to spot otherwise.
Still not sure of context of original post.
How is the pitch link control spider spherical bush and slider mechanism lubricated? If greased i imagine wear will occur, as with any bush. Play might be the first indication of this wear, as i imagine difficult access would make this hard to spot otherwise.
Still not sure of context of original post.
Last edited by Graviman; 11th Jan 2010 at 11:47. Reason: To make meaning clear.
Avoid imitations
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i imagine it is difficult to get to for inspections.
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ShyTorque, of course i do not! Reading the initial post it looked to me like the question might be along the lines of "what could it mean if...". So the any play in the cyclic could indicate some wear in the slider mechanism - seems sensible enough. Absolutely i'm not suggesting that there is any lax on the part of the engineers!
