Drone delays Westpac helicopter rescue
Good job Luke, plenty here don't understand the process of SAR.
However, you have made the error of introducing facts into the speculation which won't impress some posters...........
However, you have made the error of introducing facts into the speculation which won't impress some posters...........
wanna talk about those batteries?
sure, they're a subject mass and the energy transfer would do some damage, but hardly catastophic. they aren't solid by any means. Most lithium batteries aren't.
and they only weigh under 500grams.
sure, they're a subject mass and the energy transfer would do some damage, but hardly catastophic. they aren't solid by any means. Most lithium batteries aren't.
and they only weigh under 500grams.
Get someone to throw one at your head and then tell me they aren't solid..............................
Back of a fag packet calculation would give Kinetic Energy of a 500g battery at 500kts (257 m/s) as 16,500 Joules - still think that won't hurt a Bell blade?
Back of a fag packet calculation would give Kinetic Energy of a 500g battery at 500kts (257 m/s) as 16,500 Joules - still think that won't hurt a Bell blade?
Out of curiosity, are birdstrikes whilst maneuvering slowly or hovering in a helicopter common?
I can understand how a bird and a 150kt aircraft may meet before the bird has had time to get out of the way, but am guessing a goose or swan or for that matter a blue-tit will keep out of the way of a hovering helicopter? I suspect that in this mode of flight a drone is far likely to collide if they're anywhere near each other (i.e. filming or assisting at the same event).
I can understand how a bird and a 150kt aircraft may meet before the bird has had time to get out of the way, but am guessing a goose or swan or for that matter a blue-tit will keep out of the way of a hovering helicopter? I suspect that in this mode of flight a drone is far likely to collide if they're anywhere near each other (i.e. filming or assisting at the same event).
However, I will agree that your argument about the density/compressibility of a typical LiIon battery has some merit. It would be interesting to see a more definitive study of the relative dangers of greater mass vs. higher density vs windscreens, rotor blades, etc.
https://www.gov.uk/government/publications/drones-and-manned-aircraft-collisions-test-results
Non-birdstrike Certified Helicopter Windscreens
5.2 The non-birdstrike certified helicopter windscreen proved to have a low resistance to
all the classes of drones tested, with penetration through the windscreen shown to
occur at speeds well below the normal cruising speed of a helicopter of that type. For
the fixed-wing drone, which is itself capable of a significant speed in flight, it was
found that the drone could penetrate a helicopter windscreen of this type even if the
helicopter was stationary.
5.3 As general aviation (GA) aircraft do not have a requirement for birdstrike certification,
the result from the non-birdstrike certified helicopter could be read across to GA
aircraft with comparative severity in the result of a collision.
Birdstrike Certified Helicopter Windscreens
5.4 The birdstrike certified helicopter windscreen was found to be much more resistant,
but it was found that the quadcopter drones could penetrate these windscreens when
the closing speed was similar to the helicopter’s typical cruising speed. The speed
the fixed-wing drone can itself reach meant that it could penetrate the windscreen if
the helicopter was moving at a speed significantly below the normal cruising speed.
When the helicopter was stationary, however, it was shown that a fixed-wing drone,
when flying at its maximum speed, was unlikely to penetrate this windscreen.
Helicopter Tail Rotors
5.5 The modelling of helicopter tail rotors showed that they would be vulnerable to
impacts with all types of drones. Due to the very high speed of a rotating tail rotor
blade, it could be critically damaged by an impact with any drone.
5.6 Again, it should be noted that although the most accurate properties available were
used, the helicopter tail rotor results were based on modelling only, with no live
testing to calibrate the model.
Out of curiosity, are birdstrikes whilst maneuvering slowly or hovering in a helicopter common?
Some of the worst are the big soaring birds which tend to be less easy to see as they can be almost stationary and then suddenly get very big in the windscreen - there are plenty of stories about them ending up in the cockpit, some still alive and quite pi**ed off.
Two of my innumerable birds strikes of note.
Germany, mid seventies, low level over Germany. A flock of starling or sparrows erupt from some trees and I go IFR in birds. Lots of banging and crashing so I decide to proceed to the nearest RAFG airfield to, if nothing else, clean the blood off the windscreens.
The base is a Harrier base and as soon as I told them I had had a birdstrike they went into full emergency mode because it was a Harrier base and apparently they are allergic to birds. On shutdown I had a lot of important people surveying the damage. I took the most important up to the top deck, opened the intake and pointed out the mass of feathers and bits attached to intake struts and compressor with the normal statement that the Turmo IIIC merely converts birds to fuel. Meanwhile my crewman was levering out carcasses from the rotor head assembly.
We washed the windscreens, fired it up and punched off back to base.
The other was in China where I ran into a cormorant flying illegal IFR at 2.500 metres. It collected the radar radome and dented in so badly that it jammed the scanner which was quite inconvenient because I was dodging cu-nimbs at the time. However we survived and landed safely.
The cost of a new radome was horrendous and would have taken a couple of days to arrive.
The local car repair shop had it as new in an afternoon.
Germany, mid seventies, low level over Germany. A flock of starling or sparrows erupt from some trees and I go IFR in birds. Lots of banging and crashing so I decide to proceed to the nearest RAFG airfield to, if nothing else, clean the blood off the windscreens.
The base is a Harrier base and as soon as I told them I had had a birdstrike they went into full emergency mode because it was a Harrier base and apparently they are allergic to birds. On shutdown I had a lot of important people surveying the damage. I took the most important up to the top deck, opened the intake and pointed out the mass of feathers and bits attached to intake struts and compressor with the normal statement that the Turmo IIIC merely converts birds to fuel. Meanwhile my crewman was levering out carcasses from the rotor head assembly.
We washed the windscreens, fired it up and punched off back to base.
The other was in China where I ran into a cormorant flying illegal IFR at 2.500 metres. It collected the radar radome and dented in so badly that it jammed the scanner which was quite inconvenient because I was dodging cu-nimbs at the time. However we survived and landed safely.
The cost of a new radome was horrendous and would have taken a couple of days to arrive.
The local car repair shop had it as new in an afternoon.
Last edited by Fareastdriver; 7th Oct 2018 at 09:00.
As a student engineer I was told a (probably apocryphal) story about British Rail borrowing a "chicken cannon" normally used to test jet engines, to test the windshield of a high speed train. A chook was shot at the train, and not only penetrated the windshield, but the rear wall of the driver's cabin, doing quite a bit of damage to the machinery behind.
Upon discussing this unexpected result with the supplier of the cannon, the famous words were uttered:
"You did thaw the chicken, didn't you??"
Mass alone, momentum (mass x velocity), and even kinetic energy (1/2mv^2), is not the whole story; hardness is very relevant.
Upon discussing this unexpected result with the supplier of the cannon, the famous words were uttered:
"You did thaw the chicken, didn't you??"
Mass alone, momentum (mass x velocity), and even kinetic energy (1/2mv^2), is not the whole story; hardness is very relevant.
Originally Posted by [email protected]
Get someone to throw one at your head and then tell me they aren't solid..............................
Back of a fag packet calculation would give Kinetic Energy of a 500g battery at 500kts (257 m/s) as 16,500 Joules - still think that won't hurt a Bell blade?
Back of a fag packet calculation would give Kinetic Energy of a 500g battery at 500kts (257 m/s) as 16,500 Joules - still think that won't hurt a Bell blade?
Not as much as you think it would. I'm not denying damage, i'm disputing catastrophic damage. practice your reading comprehension
I'm not denying damage, i'm disputing catastrophic damage.
Avoid imitations
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I've known birds come through the windscreen and hit the front seat occupants in the upper body/head, causing injuries. If a drone did so, and hard parts hit the pilot in the face, I doubt he would survive.
I've also known birds come through and hit the engine levers, shutting down the engines.
I've also had a sea eagle take great objection to the helicopter I was hovering in "his" territory (SAR training with a winchman out on the cable) and he circled us a few times before attempting to attack us and almost flew through the disc. Those birds are very big..... so we cleared off! It wouldn't have been so easy if it had been a real rescue.
Seagulls don't seem to see helicopters as a threat to themselves. They don't have airborne predators and if you watch a large flock of them they often bump into each other in flight. I've had a few fly lazily into the rotor disc over the years, they made no effort to avoid us.
During a rescue there is enough to concentrate on without having to worry about some idiot flying a drone in close proximity.
I've also known birds come through and hit the engine levers, shutting down the engines.
I've also had a sea eagle take great objection to the helicopter I was hovering in "his" territory (SAR training with a winchman out on the cable) and he circled us a few times before attempting to attack us and almost flew through the disc. Those birds are very big..... so we cleared off! It wouldn't have been so easy if it had been a real rescue.
Seagulls don't seem to see helicopters as a threat to themselves. They don't have airborne predators and if you watch a large flock of them they often bump into each other in flight. I've had a few fly lazily into the rotor disc over the years, they made no effort to avoid us.
During a rescue there is enough to concentrate on without having to worry about some idiot flying a drone in close proximity.
They don't have airborne predators and if you watch a large flock of them they often bump into each other in flight.
Mass alone, momentum (mass x velocity), and even kinetic energy (1/2mv^2), is not the whole story; hardness is very relevant.
Crab, Here I thought you were splitting hairs commenting on a big bell blade cutting trees yet being so disturbed structurally hitting a meagre 500g multi packed lithium battery encased in plastic.
Lemme take my camping hatchet to the tree and then the battery and see which one takes more force to get thru.
Lemme take my camping hatchet to the tree and then the battery and see which one takes more force to get thru.
Crab, Here I thought you were splitting hairs commenting on a big bell blade cutting trees yet being so disturbed structurally hitting a meagre 500g multi packed lithium battery encased in plastic.
Lemme take my camping hatchet to the tree and then the battery and see which one takes more force to get thru.
Lemme take my camping hatchet to the tree and then the battery and see which one takes more force to get thru.