Blackhawk Question
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Blackhawk Question
Hey all,
Got a question, maybe some of you familiar with the H-60 can provide some insight? I'm blazing the trail through training as a Blackhawk Crew Chief and have run into a lot of old salties that talk about the magic behind the Cambered Fairing on the tail, saying that its capable of keeping the bird straight above xx knots without the TR doing anything. I remember reading an article about the initial design of the Hawk wanting a "fly home" capability where it could pull off cruise and a running landing with the TR shot out, but when Nick Lappos and his buds decided to make the little sharks-tooth cutout to help the TR, they gave up on getting tail-rotorless flight.
Despite this info, the guys are still adamant that the camb fairing is a magical device that keeps the bird in the air, and without it, the thing will crash and burn, every time. It's even a question in our flight progression training, "above what airspeed does the camb fairing unload the TR?" I push the issue that the thing probably does no more than the angled vertical fins on other birds (407s and longrangers come to mind) as its not very large or even a very drastic airfoil, though I have nothing to back that up.
Anyone got any idea how much the thing really does?
-Mike
Got a question, maybe some of you familiar with the H-60 can provide some insight? I'm blazing the trail through training as a Blackhawk Crew Chief and have run into a lot of old salties that talk about the magic behind the Cambered Fairing on the tail, saying that its capable of keeping the bird straight above xx knots without the TR doing anything. I remember reading an article about the initial design of the Hawk wanting a "fly home" capability where it could pull off cruise and a running landing with the TR shot out, but when Nick Lappos and his buds decided to make the little sharks-tooth cutout to help the TR, they gave up on getting tail-rotorless flight.
Despite this info, the guys are still adamant that the camb fairing is a magical device that keeps the bird in the air, and without it, the thing will crash and burn, every time. It's even a question in our flight progression training, "above what airspeed does the camb fairing unload the TR?" I push the issue that the thing probably does no more than the angled vertical fins on other birds (407s and longrangers come to mind) as its not very large or even a very drastic airfoil, though I have nothing to back that up.
Anyone got any idea how much the thing really does?
-Mike
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Re: Blackhawk Question
Mike,
If you've not already found it, the Hawkdriver website will be a useful of source of 'been there, done that' info for you.
Good luck with the training.
I/C
If you've not already found it, the Hawkdriver website will be a useful of source of 'been there, done that' info for you.
Good luck with the training.
I/C
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Re: Blackhawk Question
TwinHueyMan,
I flew the early prototypes as one of the test pilots, and was involved with this factor early on.
The vertical fin on a Black Hawk won't support powered flight home, but it can make a powered descent at about 1000 fpm possible, if you feel like being a test pilot during an emergency. The trick is to recognize the anti-torque failure (right yaw, dead pedals, heart in mouth) then get the aircraft under control (down collective, autorotate, pull engine levers if necessary). Once in a real, stable auto descent, then you can try to bring back some power, and side slip - If your copilot and pax agree that the possibility of losing control is preferable to landing into what is below you (freezing sea, 150 foot triple canopy, etc.) The way to do it is to remember that as the collective comes up and the power comes in (use torque as your guide) the aircraft will sideslip to the right, and left bank and nose down will be needed to keep the speed up and the turn stopped. If you let the speed drop, you will spin like a top and ruin your day! Keep the nose down and beady-eye the airspeed, keep it above 110 and preferably 120 KIAS. You should find that some torque can be carried while in the sideslip, and the ROD will be much less than a full auto. This will stretch your glide a bunch. At 6000 feet at 120 Kt (2 NM per minute) and 1000 fpm, you can go almost 12 miles! As you line up the place to land, get over it, then lower the collective, slip back the engine levers and auto into the place.
If you screw up and lose airspeed and the nose slides around to the right sickeningly, drop collective like a rock, cut the levers and lower the nose sharply to gain speed. Follow around the turn with the cyclic and as you pick up speed, stabilize in the auto descent, and dont try to get like Captain Midnight again!
The tail cutout was made during initial development to help the sideward flight at high altitude (45 knots at 8,000 ft DA at max weight) because it reduced the blockage of the tail rotor, but the fin was never able to let you fly home under power, regardless. In fact, I know of no tail rotor helo that can do so, period. The fenestron birds have enough tail feathers to let you fly home if light, at least one USCG dolphin has done so.
I flew the early prototypes as one of the test pilots, and was involved with this factor early on.
The vertical fin on a Black Hawk won't support powered flight home, but it can make a powered descent at about 1000 fpm possible, if you feel like being a test pilot during an emergency. The trick is to recognize the anti-torque failure (right yaw, dead pedals, heart in mouth) then get the aircraft under control (down collective, autorotate, pull engine levers if necessary). Once in a real, stable auto descent, then you can try to bring back some power, and side slip - If your copilot and pax agree that the possibility of losing control is preferable to landing into what is below you (freezing sea, 150 foot triple canopy, etc.) The way to do it is to remember that as the collective comes up and the power comes in (use torque as your guide) the aircraft will sideslip to the right, and left bank and nose down will be needed to keep the speed up and the turn stopped. If you let the speed drop, you will spin like a top and ruin your day! Keep the nose down and beady-eye the airspeed, keep it above 110 and preferably 120 KIAS. You should find that some torque can be carried while in the sideslip, and the ROD will be much less than a full auto. This will stretch your glide a bunch. At 6000 feet at 120 Kt (2 NM per minute) and 1000 fpm, you can go almost 12 miles! As you line up the place to land, get over it, then lower the collective, slip back the engine levers and auto into the place.
If you screw up and lose airspeed and the nose slides around to the right sickeningly, drop collective like a rock, cut the levers and lower the nose sharply to gain speed. Follow around the turn with the cyclic and as you pick up speed, stabilize in the auto descent, and dont try to get like Captain Midnight again!
The tail cutout was made during initial development to help the sideward flight at high altitude (45 knots at 8,000 ft DA at max weight) because it reduced the blockage of the tail rotor, but the fin was never able to let you fly home under power, regardless. In fact, I know of no tail rotor helo that can do so, period. The fenestron birds have enough tail feathers to let you fly home if light, at least one USCG dolphin has done so.
Last edited by NickLappos; 9th Jan 2006 at 02:12.
Re: Blackhawk Question
The way to do it is to remember that as the collective comes up and the power comes in (use torque as your guide) the aircraft will sideslip to the right, and left bank and nose down will be needed to keep the speed up and the turn stopped. If you let the speed drop, you will spin like a top and ruin your day!
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Re: Blackhawk Question
Nick is pretty much spot on here.
We have practiced this EP many times in the Ozzy Black Hawk sim with good results. The S-70 is capable of dumping fuel and ESSS and external load jettisons hence if you can reduce AUW this will also require less power required to maintain level and hence less TQ. At low AUW it is possible in certain circumstances to stretch the glide and manouevre to a position where a flared attitude running landing with PCL chop can be effected. Good Crew coordination and CRM are essential for the termination. If the termination area cannot suppport a flared attitude running landing then a standard auto neds to be flown due obstacles and terrain.
As for magic airspeeds and formulas there are none. Concepts are the key. Airspeed ~ 100 + kts to keep the 1/2 row v2 over the vertical fin and just enough TQ to stretch the glide while reducing AUW, Left and forward cyclic for side slip and descent (shallow descent).
If you have enough training, experience and a suitable termination area then you may be able to send all concerned an e-mail to let us know the secret.
At the point of t/r loss of thrust or drive shaft failure there will also be a vibe felt in the machine, a yaw to the right and a potential pitch up as components of the t/r are lost/fail and C of G changes.
The great thing about the Black Hawk family is the ability of the under carriage to absorb high Rates of descent (typically 2500 ft/min) and keep the fusalage and crew in one piece.
Best of luck.
Np formulas or numbers apply known concepts!
Lasty.
We have practiced this EP many times in the Ozzy Black Hawk sim with good results. The S-70 is capable of dumping fuel and ESSS and external load jettisons hence if you can reduce AUW this will also require less power required to maintain level and hence less TQ. At low AUW it is possible in certain circumstances to stretch the glide and manouevre to a position where a flared attitude running landing with PCL chop can be effected. Good Crew coordination and CRM are essential for the termination. If the termination area cannot suppport a flared attitude running landing then a standard auto neds to be flown due obstacles and terrain.
As for magic airspeeds and formulas there are none. Concepts are the key. Airspeed ~ 100 + kts to keep the 1/2 row v2 over the vertical fin and just enough TQ to stretch the glide while reducing AUW, Left and forward cyclic for side slip and descent (shallow descent).
If you have enough training, experience and a suitable termination area then you may be able to send all concerned an e-mail to let us know the secret.
At the point of t/r loss of thrust or drive shaft failure there will also be a vibe felt in the machine, a yaw to the right and a potential pitch up as components of the t/r are lost/fail and C of G changes.
The great thing about the Black Hawk family is the ability of the under carriage to absorb high Rates of descent (typically 2500 ft/min) and keep the fusalage and crew in one piece.
Best of luck.
Np formulas or numbers apply known concepts!
Lasty.
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Re: Blackhawk Question
Thanks for the details guys! Some additional comments:
1) The stuff I describe was not tested in flight, it was studied using the research simulators at Sikorsky.
2) NEVER believe a training simulator for these kind of screwy emergencies, it wasn't built to do it right, and it will lie to you, usually making the emergency seem easier. I have set up perhaps 5 training sims, and they are never validated in regimes outside of the normal envelope, yet I have seen pilots try to autorotate at 70% Nr, or sideslip without a tail rotor and climb, and declare these things somehow do-able. The only simulation that can be used for screwy, out of the envelope flight are the research sims that the company's engineers set up specifically to look at the problem, and even then we use a grain of salt with the data. The training sim will give you the hang of it, though, so it is great for practice, just don't count on the aircraft to do what the sim does. The WPB Flight Safety S-76 Sim will allow you to fly out of a TR failure in a high hover (!!!)
1) The stuff I describe was not tested in flight, it was studied using the research simulators at Sikorsky.
2) NEVER believe a training simulator for these kind of screwy emergencies, it wasn't built to do it right, and it will lie to you, usually making the emergency seem easier. I have set up perhaps 5 training sims, and they are never validated in regimes outside of the normal envelope, yet I have seen pilots try to autorotate at 70% Nr, or sideslip without a tail rotor and climb, and declare these things somehow do-able. The only simulation that can be used for screwy, out of the envelope flight are the research sims that the company's engineers set up specifically to look at the problem, and even then we use a grain of salt with the data. The training sim will give you the hang of it, though, so it is great for practice, just don't count on the aircraft to do what the sim does. The WPB Flight Safety S-76 Sim will allow you to fly out of a TR failure in a high hover (!!!)
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Re: Blackhawk Question
SIMS are only as good as the flight model that supports them-agreed. Real data is hard to come by as there would be few QTP's that would volunteer to collect test data points for this EP real time.
As discussed a knowledge of concepts is required. As for letting the NR get to 70% holy S - - T Bat Man, sounds like a death wish not to mention undervoltage protection kicking in below 85% NR, which now means dealing with the EP with no AFCS, Stabilator, generators and inside indications of actaul rortor speed at this point (unless APU start). At 70% NR the blades fold up do a clap and you glide like the titanic.
Food for thought.
Lasty.
As discussed a knowledge of concepts is required. As for letting the NR get to 70% holy S - - T Bat Man, sounds like a death wish not to mention undervoltage protection kicking in below 85% NR, which now means dealing with the EP with no AFCS, Stabilator, generators and inside indications of actaul rortor speed at this point (unless APU start). At 70% NR the blades fold up do a clap and you glide like the titanic.
Food for thought.
Lasty.
Re: Blackhawk Question
Ni Nick,
You said,
I think the Eurocopter AS350 can sustain cruise with a completley stopped tailrotor. I saw a video once of a AS350 landing on a runway in the southern states a few years back at about 80 miles an hour. I was told he even managed to do a couple approaches.
Does anyone have that video??
Later,
bb
You said,
Originally Posted by NickLappos
....In fact, I know of no tail rotor helo that can do so, period. The fenestron birds have enough tail feathers to let you fly home if light, at least one USCG dolphin has done so.
Does anyone have that video??
Later,
bb
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Re: Blackhawk Question
bb in ca,
Sounds interesting, could be true, does anyone have an approximate date? This is the only NTSB record that comes close, and it sounds like the occurrence, which was a bad pitch link and vibration, the TR failed in the hover upon landing, it was not a fly home without a TR:
http://www.ntsb.gov/ntsb/brief.asp?e...12X20041&key=1
NTSB Identification: NYC00LA021 .
The docket is stored in the Docket Management System (DMS). Please contact Records Management Division
14 CFR Part 91: General Aviation
Accident occurred Wednesday, October 27, 1999 in WESTBURY, NY
Probable Cause Approval Date: 11/30/2000
Aircraft: Eurocopter AS-350-BA, registration: N350SL
Injuries: 1 Uninjured.
While in cruise flight, the pilot detected a severe vibration and initially elected to return to his departure airport, and then elected to perform a precautionary landing. When the pilot brought the helicopter to a hover, the helicopter rotated nose left. The pilot then landed, shut down the engine, and noticed the tail rotor gear box and vertical fin had separated from the helicopter. One of the tail rotor pitch link control rods was found to have failed. Metallurgical examination of the failed components, found evidence of fatigue on the failed tail rotor pitch link control rod. The manufacturer specified an after last flight of the day (ALF) inspection, as a detailed inspection of the helicopter that could be performed by pilots or maintenance personnel. The Director of Maintenance for the operator reported pilots were responsible for all daily checks. The pilot had not been trained to conduct this inspection, and the FAA check airman who conducted the pilot's initial FAR 135 checkride was not aware of the specifics of the ALF inspection. In addition, the checklist found in the helicopter had not been updated with the latest, more detailed ALF inspection.
The National Transportation Safety Board determines the probable cause(s) of this accident as follows:
the failure of the operator to ensure the pilot was adequately trained to conduct all inspections required by the flight manual, which resulted in the pilot's inadequate preflight and subsequent failure of the tail rotor pitch change rod. Factors were the inadequate preflight by the pilot, and the failure of the FAA to detect the deficiency in the pilot's training, and ensure that the operator used the most current checklist available.
Sounds interesting, could be true, does anyone have an approximate date? This is the only NTSB record that comes close, and it sounds like the occurrence, which was a bad pitch link and vibration, the TR failed in the hover upon landing, it was not a fly home without a TR:
http://www.ntsb.gov/ntsb/brief.asp?e...12X20041&key=1
NTSB Identification: NYC00LA021 .
The docket is stored in the Docket Management System (DMS). Please contact Records Management Division
14 CFR Part 91: General Aviation
Accident occurred Wednesday, October 27, 1999 in WESTBURY, NY
Probable Cause Approval Date: 11/30/2000
Aircraft: Eurocopter AS-350-BA, registration: N350SL
Injuries: 1 Uninjured.
While in cruise flight, the pilot detected a severe vibration and initially elected to return to his departure airport, and then elected to perform a precautionary landing. When the pilot brought the helicopter to a hover, the helicopter rotated nose left. The pilot then landed, shut down the engine, and noticed the tail rotor gear box and vertical fin had separated from the helicopter. One of the tail rotor pitch link control rods was found to have failed. Metallurgical examination of the failed components, found evidence of fatigue on the failed tail rotor pitch link control rod. The manufacturer specified an after last flight of the day (ALF) inspection, as a detailed inspection of the helicopter that could be performed by pilots or maintenance personnel. The Director of Maintenance for the operator reported pilots were responsible for all daily checks. The pilot had not been trained to conduct this inspection, and the FAA check airman who conducted the pilot's initial FAR 135 checkride was not aware of the specifics of the ALF inspection. In addition, the checklist found in the helicopter had not been updated with the latest, more detailed ALF inspection.
The National Transportation Safety Board determines the probable cause(s) of this accident as follows:
the failure of the operator to ensure the pilot was adequately trained to conduct all inspections required by the flight manual, which resulted in the pilot's inadequate preflight and subsequent failure of the tail rotor pitch change rod. Factors were the inadequate preflight by the pilot, and the failure of the FAA to detect the deficiency in the pilot's training, and ensure that the operator used the most current checklist available.
Re: Blackhawk Question
I too had heard of of a 80 MPH run-on by an AStar. My recollection hints at a control problem from failed hydraulics (that toothed belt let go), not a stopped tail-rotor.
From my time in simulators, I've noticed a wide variance in simulator reproductions of emergencies - some you can land with a blown off tailrotor (flightsafety), some you can't (CAE) for the same aircraft. Modelling in a sim is supposed to be within a percent of actual or so, but nobody fails a tailrotor as part of the sim data collection. However, with all the FDR/HUMS systems now part of helicopters, it should be standard practice for sims to update their modelling after new data from a crash is made available.
From my time in simulators, I've noticed a wide variance in simulator reproductions of emergencies - some you can land with a blown off tailrotor (flightsafety), some you can't (CAE) for the same aircraft. Modelling in a sim is supposed to be within a percent of actual or so, but nobody fails a tailrotor as part of the sim data collection. However, with all the FDR/HUMS systems now part of helicopters, it should be standard practice for sims to update their modelling after new data from a crash is made available.
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Re: Blackhawk Question
Don't for a second believe the training sim on how it behaves in a TR failure, except after you enter the autorotation. The problem is that there is no real data to validate the sim with, and the complex cross couplings (yaw to roll, yaw to pitch interactions) and near stall behaviors are WAY beyond what training sims are designed to do. It fools everybody, because the cockpit looks great, the instruments all work, and the thing behaves sort of like it should, but it is flat wrong to believe it if you are out of the normal flight envelope.
Trust me on this, I have been the test pilot who gathered the flight data and then tried to make the training sims behave like the aircraft. It is hard enough making it look real within the envelope. Outside, it is no better than a guess, and any similarity between what the sim does and what the aircraft does is luck. To write an emergency procedure for an extreme maneuver based on a training sim, and then hope it will work in the real world is a recipe for disaster.
Trust me on this, I have been the test pilot who gathered the flight data and then tried to make the training sims behave like the aircraft. It is hard enough making it look real within the envelope. Outside, it is no better than a guess, and any similarity between what the sim does and what the aircraft does is luck. To write an emergency procedure for an extreme maneuver based on a training sim, and then hope it will work in the real world is a recipe for disaster.
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Re: Blackhawk Question
If you can access the archives @ Ft. Rucker, AL, USA, I'm sure you'll find an amazing video of a flight of 3 Hawks . Number 2 (stag.rt) T/R is completely stopped and continues flight for quite some time. The crew were oblivious to the malfunction. When we went through the AQC this film was part of the Malfunction Analysis course . Also, in the flight sim, it's possible to keep continued flight up, but it's directly dependent on the G/W and of course the pilots abilities. The chord on the fin is pretty powerful, just the way Igor wanted it to be. Sikorsky had so much faith in it's ability to help you out in case of a T/R problem, they even describe the airspeeds and techniques in the Emergency procedures. The Mixing Unit has a certain part to play, but then that is related to the overall G/W.
Did I mention the T/R produces 2.5% of the overall lift. Would this have an effect too???
Did I mention the T/R produces 2.5% of the overall lift. Would this have an effect too???
Re: Blackhawk Question
I think the Eurocopter AS350 can sustain cruise with a completley stopped tailrotor. I saw a video once of a AS350 landing
