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Old 18th May 2017, 01:04   #41 (permalink)
 
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Quote:
Originally Posted by John Eacott View Post
I imagine it says what you posted in post #9?

If you're implying the photo of VH-BKK was me or my company with a 20-30' strop then you're sadly mistaken. I took that photo while flying in company; my ops we either had the Bambi on the hook or on a 100' kevlar line. My reference to 'we' was that in the 90's we were all on a learning curve and shared experiences, pilots do that. Or used to.
I'm not implying anything about you or your previous company.

It's just bad information suggesting that a Bambi flies fine on a short strop as indicated by your pics. Someone new to bucket ops will go and try it out because they read it here.

Sure it might fly just fine 99% of the time but sadly aircraft accidents have proven otherwise.
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Old 18th May 2017, 07:18   #42 (permalink)
 
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Looking at the pix you would need some very sporty handling to get the bucket to hit the tail in the BK example !
I was just curious in how the minimum of 50 ft on a line actually came from, i.e. who did the physics to say that was safe and say 40 ft wasn't !
Nigel, I must have sat behind you at the back of the classroom
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Old 18th May 2017, 12:22   #43 (permalink)
 
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Originally Posted by Hughes500 View Post
I was just curious in how the minimum of 50 ft on a line actually came from
Most likely from flight-testing of the Bambi's, as it is taken from the user manual for the buckets and 50ft has been deemed to be long enough to avoid this problem.

Quote:
need some very sporty handling
Associated with turbulence close to the fire/ground and a bit uncoordinated handling, it is possible as there is not a single factor leading to this. It is not happening every time obviously (was probably not the pilots first bucket either!?), but this thread illustrates that it can happen!

John's pictures seems to be taken in cruise with unknown speed and away from the fire and ground with presumably smoother winds/turbulence (stable flight). The BK's tail is also higher than on the 350 which is the machine in question, so less exposed to the problem. The middel picture seems to be from (close to) hover.....

As for gullibell's ''rule of thumb''. It is not restrictive enough as there is only half the distance of the overall length of the helicopter between the hook and t/r tips, so therefore the total length of the helicopter is irrelevant...
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Old 18th May 2017, 17:06   #44 (permalink)
 
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For those at the back of the class -

Still photos of the bucket in a cruise are NOT what you should be looking at.

Find some youtube material of when the bucket is emptying and that will change your outlook.

As it goes from bag of water to windsock there is an overshoot of the stable windsock attitude towards the tail. The overshoot magnitude is tied to speed.

And with respect to line length - look up what makes a pendulum period longer or shorter - good starting point.
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Old 18th May 2017, 18:50   #45 (permalink)
 
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RVDT

Yup always was at the back of the class, but always like to ask. Done lots of lifting with different lines but was curious how the 50ft length had been derived at, obviously / hopefully not be experimenting with a helicopter ! Done a bit of bucket work, but not much happens here in UK, so would prefer to ask what to some might be the stupid question !
When dumping water have never really seen the bucket fly up that much then I suppose haven't been doing more than about 30 kts and its been on a 50 ft line or to belly hook but nothing in between
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Old 18th May 2017, 19:39   #46 (permalink)
 
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Regardless of line length the fact you have a underslung load means you have to give it the respect it deserves.
Even with a 200 ft line i have heard of guys getting the line over the back of the skids and have seen empty lines very close to TRs when ferrying an empty line.
I have used a Bambi on a 30 ft line with no problem, the 30 ft bit was chain though and gave the overall load extra weight when there was no water in the bucket.
If not treated with the respect it deserves and the helicopter flown accordingly it will bite.
Actually that's flying full stop isn't it
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Old 18th May 2017, 20:48   #47 (permalink)
 
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This is at a relatively slow speed in ideal conditions -

Notice how much it moves towards the tail.

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Old 19th May 2017, 00:44   #48 (permalink)
 
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The comments about the stability of the Bambi following a drop are, of course, quite correct. It may be worth noting that the lines we used back in the 90s were steel and very heavy, which influenced not only the flight characteristics but also the length of the line. 30ft (we weren't much into metrics) was about the limit of steel cable that could be handled by a pilot, especially when we started adding not just the household cable to run power to the solenoid but also a hose for the feed from the Sacksafoam! With the introduction of kevlar lines this restriction disappeared overnight and 100ft became the norm of what could be handled by one man.
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Old 22nd May 2017, 20:02   #49 (permalink)
 
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Quote:
Originally Posted by John Eacott View Post
The comments about the stability of the Bambi following a drop are, of course, quite correct. It may be worth noting that the lines we used back in the 90s were steel and very heavy, which influenced not only the flight characteristics but also the length of the line. 30ft (we weren't much into metrics) was about the limit of steel cable that could be handled by a pilot, especially when we started adding not just the household cable to run power to the solenoid but also a hose for the feed from the Sacksafoam! With the introduction of kevlar lines this restriction disappeared overnight and 100ft became the norm of what could be handled by one man.
Interesting Discussion. I don't do bucket work, but I did a similar risk assessment for powerline work years back and did a study on this very hazard. at the time I found 12 such incidents in the US alone between 1983 and 2007 where a longline or load on a longline (or directly on the belly hook) contacted the tail rotor. Two of the 12 resulted in fatalities.

Below are the accident report #s
ATL83LA294 SEA87LA092 ANC92FA040 LAX94LA241 SEA98LA017 ANC98LA003 SEA00LA028 DEN01LA145 DEN03LA041 LAX03LA160 LAX04LA116 SEA07CA200
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Old 23rd May 2017, 07:59   #50 (permalink)
 
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For interest look up the "hairy rope trick" of long lining with a fixed wing.

It used to be done with fixed wings (Tiger Moth) so is pre-interweb days so may be difficult to find information.

Basically pay out a long "hairy" line and enter a turn and the end can be controlled via bank angle to place it on the ground.

There are stories of a certain chap long line / bucketing with a Cresco ag plane in NZ if you can believe that.

Was used in the 1950's - more information here and relevant to the issue for information purposes.
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Old 23rd May 2017, 21:05   #51 (permalink)
 
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"In NZ"... totally believable...

The Kiwi's poineered the 2 helicopter lift.... probably

Commercial operations | Southern Lakes Helicopters, Fiordland, New Zealand

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Old 23rd May 2017, 22:10   #52 (permalink)
 
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Originally Posted by BigMike View Post
"In NZ"... totally believable...

The Kiwi's poineered the 2 helicopter lift.... probably

Commercial operations | Southern Lakes Helicopters, Fiordland, New Zealand

What could possibly go wrong.....
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Old 24th May 2017, 00:29   #53 (permalink)
 
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This will give me nightmares. Make the image go away!
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Old 24th May 2017, 10:26   #54 (permalink)
 
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[quote=krypton_john;9780458]This will give me nightmares. Make the image go away![/quote

One of the dumbest things I've ever seen

Last edited by rottenjohn; 24th May 2017 at 10:51.
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Old 24th May 2017, 11:13   #55 (permalink)
 
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Would love to see the risk assessment of this and the safety management system !
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Old 24th May 2017, 15:28   #56 (permalink)
 
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That has got to be a photoshop job, surely?!
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Old 24th May 2017, 20:56   #57 (permalink)
 
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Originally Posted by Nubian View Post
What could possibly go wrong.....


People never cease to amaze me when it comes to efforts they put into suicide attempts.
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Old 24th May 2017, 21:10   #58 (permalink)
 
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I remember this being done years ago in NZ at an airshow, or somewhere similar, by 2 500's with longlines. 200ft? They were lifting a hut then if I remember rightly.
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Old 24th May 2017, 21:13   #59 (permalink)
 
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Originally Posted by jimcarler View Post
That has got to be a photoshop job, surely?!
You wouldn't be blamed for assuming that but I've seen the video, its genuine, spreader bar was apparently built for use by 2 500s and then extended for the Squirrels,
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Old 24th May 2017, 21:21   #60 (permalink)
 
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No this is real.
The other option would be getting the RNZAF and their NH90. As per another thread on here.
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