Lynx Aerobatics!
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Lynx Aerobatics!
I'm probably well behind the drag curve here but not having seen the Lynx display for a fair while, I was treated to a display by the Blue Eagles Lynx at Dunsfold last Sunday and amazed to see it doing full loops and barrel rolls.
As far as I'm aware, this was not possible a few years ago and was certainly not a part of their display routine so has it been made possible by the advent of the BERP blades?
It was certainly very impressive!
As far as I'm aware, this was not possible a few years ago and was certainly not a part of their display routine so has it been made possible by the advent of the BERP blades?
It was certainly very impressive!
As far as I'm aware, this was not possible a few years ago and was certainly not a part of their display routine so has it been made possible by the advent of the BERP blades?
AFCS tripping-out, perhaps?
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i think its more to do with the titanium head than the BERP blades but stand ready to be corrected.
As for the AFCS- i know that the CAC was disengaged during 'backflips' in the lynx...
Surely theres a light blue still on pprune to provide more timely and knowledgeable info tho...
And yes it is a very good display.
As for the AFCS- i know that the CAC was disengaged during 'backflips' in the lynx...
Surely theres a light blue still on pprune to provide more timely and knowledgeable info tho...
And yes it is a very good display.
I'm a long, long way out of the loop now but I thought that the Lynx was always capable of such things but was stopped from doing it in the late 80s due to excessive fatigue life useage on the rotor head. Maybe this isn't an issue any more - different rotor heads?
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The Lynx has always been capable of the aerobatics you talk about. It has only stopped if the routine didn't need it or the RTS wasn't signed (only happened once and such a fuss that they reversed the decision!).
The reason it can are
1 - bloody good pilots
2 - baffles in the engines so it doesn't go quiet (Navy don’t have them I believe?)
3 - Gallons of power in temperate climates.
4 - a good response from the public making the BEs want to keep doing it.
The fixed head makes it manoeuverable and capable (it wont chop its tail off as a flexible head would under -G forces)
The old Mk1 didn't have a lot of power so was less capable but the pilots did try their hardest!!!!!
Hope this helps.
The reason it can are
1 - bloody good pilots
2 - baffles in the engines so it doesn't go quiet (Navy don’t have them I believe?)
3 - Gallons of power in temperate climates.
4 - a good response from the public making the BEs want to keep doing it.
The fixed head makes it manoeuverable and capable (it wont chop its tail off as a flexible head would under -G forces)
The old Mk1 didn't have a lot of power so was less capable but the pilots did try their hardest!!!!!
Hope this helps.
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Ironically the BERP blades limited the Lynx in it's display flight envelope more than the good 'ole metal blades!
It is also true that the Army Air Corps Lynx has inverted flight engine oil baffles whereas the Navy Lynx's do not. That leads to the fantastic display that the AAC produce. I particularly like the 'back flip' at the end. Careful use of the collective to prevent a head overspeed!
The fantastic handling capabilities of the Lynx come mainly from it having, at light weight, plenty of power and a semi rigid rotor head. Perfect for deck landing.
The reason the BERP blades limited the Lynx was that as they were composite they flexed in flight far more than the metal blades did. This was transmitted along the blade to the head and manifested itself as vibrations. BERP was designed for high speed level flight countering retreating blade stall, supersonic shock and vortex cutting. In the Navy Lynx the max AOB for the metal blades was 90 degrees, that was reduced to 60 degrees for the BERP bladed aircraft.
Not sure about the current limits as the aircraft has a different 2 piece rotor head now with the mast and the cross being two separately machined pieces. The original had a single piece machine titanium mast and cross piece. Amazing piece of engineering.
Was and still is the best helicopter I have had the privilege to fly. (and display
)
(I also assume by 'Light Blue' you mean the colour of the AAC beret?)
It is also true that the Army Air Corps Lynx has inverted flight engine oil baffles whereas the Navy Lynx's do not. That leads to the fantastic display that the AAC produce. I particularly like the 'back flip' at the end. Careful use of the collective to prevent a head overspeed!
The fantastic handling capabilities of the Lynx come mainly from it having, at light weight, plenty of power and a semi rigid rotor head. Perfect for deck landing.
The reason the BERP blades limited the Lynx was that as they were composite they flexed in flight far more than the metal blades did. This was transmitted along the blade to the head and manifested itself as vibrations. BERP was designed for high speed level flight countering retreating blade stall, supersonic shock and vortex cutting. In the Navy Lynx the max AOB for the metal blades was 90 degrees, that was reduced to 60 degrees for the BERP bladed aircraft.
Not sure about the current limits as the aircraft has a different 2 piece rotor head now with the mast and the cross being two separately machined pieces. The original had a single piece machine titanium mast and cross piece. Amazing piece of engineering.
Was and still is the best helicopter I have had the privilege to fly. (and display
) (I also assume by 'Light Blue' you mean the colour of the AAC beret?)
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(I also assume by 'Light Blue' you mean the colour of the AAC beret?)
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Saw it at Bournemouth today
Announcer said that its the titanium head and disengaging the computer control systems. The displaying Navy Lynxes can apparently do this but because they're training aircraft in their day jobs they don't like to stress the airframe, although it was an ex-RAF commentator.
Sea Vixen also in the air - wow!
Sea Vixen also in the air - wow!
Announcer said that its the titanium head and disengaging the computer control systems. The displaying Navy Lynxes can apparently do this but because they're training aircraft in their day jobs they don't like to stress the airframe, although it was an ex-RAF commentator
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Thanks for the info guys!
Thanks too to the Typhoon team for their dual vertical departure from Dunsfold. A very effective (and loud!) demonstration of the sheer grunt available to the RAF again at long last!
Thanks too to the Typhoon team for their dual vertical departure from Dunsfold. A very effective (and loud!) demonstration of the sheer grunt available to the RAF again at long last!
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The Navy aircraft, although physically and aerodynamically capable of the same maneuver do not have the engine inverted oil baffles fitted. Unless positive G were held throughout the maneuver then there is the possibility of oil loss from the engines.
A fair few Navy Lynx have been barrel rolled though!
I also seem to remember that Westlands did not endorse the structural integrity of the display airframe during these maneuvers stating that it was outside of the tested flight envelope. I couldn't confirm if that came direct from Westlands though.
What is interesting to note though is that even though the Navy Lynx operate in one of the most aviation component hostile environments on the planet the AAC have a far higher AOG rate than the RN. Coincidence or just handling differences?
A fair few Navy Lynx have been barrel rolled though!
I also seem to remember that Westlands did not endorse the structural integrity of the display airframe during these maneuvers stating that it was outside of the tested flight envelope. I couldn't confirm if that came direct from Westlands though.
What is interesting to note though is that even though the Navy Lynx operate in one of the most aviation component hostile environments on the planet the AAC have a far higher AOG rate than the RN. Coincidence or just handling differences?
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Used to see them flight testing Lynx(es?) and other stuff when I worked at Westlands at Weston on the Mud. Occasionally used to stop us gliding on summer courses when they wanted to test something. Pretty impressive stuff
This was back in the early 80s
Seem to remember the Lynx could do backward loops
and it certainly had the speed record for flying backwards at some point.
This was back in the early 80s
Seem to remember the Lynx could do backward loops
and it certainly had the speed record for flying backwards at some point.
Below the Glidepath - not correcting
Anorak and tartan flask alert
Although the baffles prevent oil starvation and donk failures when inverted, the aerodynamic handling qualities of the Lynx are due to the rigid rotor. Most helicopter blades are attached to the Main Rotor head via physical horizontal and vertical hinges, the horizontal hinges (fwd and aft movement of the blade from the extension arm) have a drag damper to control the movement, but the vertical movement (up and down movement) of the blade is a function of aerodynamic forces, other than a droop stop stopping it going down too far. The Lynx, by comparison, achieves this with a rigid Titanium extension arm that holds the blades in place, and all vertical and horizontal movement of the blade is a function of the flexing action of the titanium. The reaction of the controls input is far more rapid with a rigid head (and is actually damped out by the AFCS), but when inverted, the blades can not "clap hands" as they can with a conventional head when negative G is encountered, because the titanium head holds then in place. The secret of rolling or looping in conventional helicopter is holding positive G, so the aerodynamic force on the blade (which would force the blades to "cone" up into a V, relative to the fuselage) is countered by centifugal/centripetal force and gravity. Failure to maintain positive G usually results in the rotor cutting off some fairly important bits down the back end and a guaranteed seat (posthumously) at the BOI.
For spotters, when parked on the dispersal, blades on conventional heads always droop down, blades on rigid rotors stay erect.
Wobble2plank:
One word - Spares.
For spotters, when parked on the dispersal, blades on conventional heads always droop down, blades on rigid rotors stay erect.
Wobble2plank:
What is interesting to note though is that even though the Navy Lynx operate in one of the most aviation component hostile environments on the planet the AAC have a far higher AOG rate than the RN. Coincidence or just handling differences?
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Two's in,
I would love to agree with you on the spares issue but, unfortunately, it's the other way round.
After the AAC tail rotor drive shaft failure all Lynx aircraft were to have their tail rotor drive shafts re-shimmed and aligned. I could not find any shim packs for the tail shafts due to the fact that they were all at Middle Wallop. Same goes for the rotor heads, AAC had priority after a Netherlands Lynx threw a blade during a ground run caused by scratching of the titanium head. My nice rotor head, with more than a few thousand hours left on it became AOG over night. Where did all the new bolted ones go? Correct AAC. Engines, Heads, gearboxes and dog bones (Tie bars) all head MW first.
It's not the AAC's doings its the Navys crap ordering.
Enjoy.
I would love to agree with you on the spares issue but, unfortunately, it's the other way round.
After the AAC tail rotor drive shaft failure all Lynx aircraft were to have their tail rotor drive shafts re-shimmed and aligned. I could not find any shim packs for the tail shafts due to the fact that they were all at Middle Wallop. Same goes for the rotor heads, AAC had priority after a Netherlands Lynx threw a blade during a ground run caused by scratching of the titanium head. My nice rotor head, with more than a few thousand hours left on it became AOG over night. Where did all the new bolted ones go? Correct AAC. Engines, Heads, gearboxes and dog bones (Tie bars) all head MW first.
It's not the AAC's doings its the Navys crap ordering.
Enjoy.
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Seem to remember Ch&* Cha(*&s saying to me 'don't do this when you get to 847!' on my Lynx Conversion. I thought I was going to die!! Never had the bottle to do it myself though!! Timex might have??
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Lynx Aerobatics
The first rolls with Lynx were done in August 1972 by Roy Moxam in one of the prototype aircraft (XW837) and John Morton in the Naval prototype (XX 469). Both aircraft were fully instrumented to measure stress.
Loops came shortly after.
The reason the AFCS was disengaged was because it tries to do its job and fly the aircraft, making handling difficult and adding some stress inputs.
The engine manufacturer did'nt like it because it played havoc with the oil system, which was never designed for inverted flight.
The only purpose of the exercise was to demonstrate the control power available from the semi-rigid head.
There isn't much justification for a fully aerobatic helicopter, yes I know its fun!
BERP blades did improve the situation, and the manoeuvre programme was carried out to fully understand the limitations but the whole thing really starts with the rotor head.
Retired Westland Flight Test Engineer
Loops came shortly after.
The reason the AFCS was disengaged was because it tries to do its job and fly the aircraft, making handling difficult and adding some stress inputs.
The engine manufacturer did'nt like it because it played havoc with the oil system, which was never designed for inverted flight.
The only purpose of the exercise was to demonstrate the control power available from the semi-rigid head.
There isn't much justification for a fully aerobatic helicopter, yes I know its fun!
BERP blades did improve the situation, and the manoeuvre programme was carried out to fully understand the limitations but the whole thing really starts with the rotor head.
Retired Westland Flight Test Engineer
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Blimey, this reminds me (pull a sandbag etc) of a couple of days 'interesting' flying near Stonehenge. Assymetric heavy load (not including me as FTO) doing full vibe and stress for RTS reccs.
Thoroughly enjoyed that one
And we didn't break the frame, allegedly it fell off a boat into the deep blue sea somewhere else.
Thoroughly enjoyed that one
And we didn't break the frame, allegedly it fell off a boat into the deep blue sea somewhere else.
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wobble2plank,
Lift off from boat, S&L across ogsplosh, sit in hover, S&L back to boat, land on boat, wash it down, shove it in hangar.
or
Tactical flying/sandy environment/lifting blokes/sandy environment/cab at MAUM/cab sat in the sun day in, day out/sandy environment.
Or you could look at is as the Admirals staff car compared to a WMIK.
Stop whinging at the AAC then poindexter! Sounds like sour grapes because we can have fun with our cabs. 
As an aside, there is usually only a couple of aircraft at Wallop that are in the Eagle 1 role. These are fitted with G meters and are thoroughly checked. Its not as if the rest of the AAC are routinely doing backflips, barrel rolls and loops (well, not since S Armagh got binned any way....)
What is interesting to note though is that even though the Navy Lynx operate in one of the most aviation component hostile environments on the planet the AAC have a far higher AOG rate than the RN. Coincidence or just handling differences?
or
Tactical flying/sandy environment/lifting blokes/sandy environment/cab at MAUM/cab sat in the sun day in, day out/sandy environment.
Or you could look at is as the Admirals staff car compared to a WMIK.
It's not the AAC's doings its the Navys crap ordering.
As an aside, there is usually only a couple of aircraft at Wallop that are in the Eagle 1 role. These are fitted with G meters and are thoroughly checked. Its not as if the rest of the AAC are routinely doing backflips, barrel rolls and loops (well, not since S Armagh got binned any way....)