Helicopter Tree Sawing In The MD 500 - Page 1
Forum section: electronics / general

author: Wan Huang Luo
author_rank: Regular Contributor
timestamp: December 13, 2018, 01:00:31 am
content: When there’s an easement, there’s a way

author: xrunner
author_rank: Super Contributor
timestamp: December 13, 2018, 01:05:13 am
content: And if it gets tangled up and can't be released ... what happens exactly?

author: beanflying
author_rank: Super Contributor
timestamp: December 13, 2018, 01:21:23 am
content: That's so last Century. And Because Christmas is coming here she is .....https://youtu.be/rF1vfMM3W08

author: Red Squirrel
author_rank: Super Contributor
timestamp: December 13, 2018, 09:37:22 pm
content: Quote from: xrunner on December 13, 2018, 01:05:13 amI would assume they can detach it. Hopefully it would also turn it off in the process.The piloting skills for this are pretty good, helicopters are hard enough to fly as is, a weight like this must make things interesting.

author: Wan Huang Luo
author_rank: Regular Contributor
timestamp: December 13, 2018, 10:21:12 pm
content: Quote from: Red Squirrel on December 13, 2018, 09:37:22 pmDefinitely takes a lot of training and experience to wrangle one of these around. Speaking from a physics perspective, there's a lot of forces at work here.

author: cdev
author_rank: Super Contributor
timestamp: December 14, 2018, 02:14:25 am
content: I'm sure the high tension wires are farther away than they look...

author: xrunner
author_rank: Super Contributor
timestamp: December 14, 2018, 03:24:39 am
content: Quote from: cdev on December 14, 2018, 02:14:25 amNothing can go wrong ...

author: beanflying
author_rank: Super Contributor
timestamp: December 14, 2018, 03:31:24 am
content: The pendulum effects of the system would make flying horrid. There is a reason Helicopters try and get their mass close to the rotors.Interesting additional info here and some pilot comments on flying one of them.https://www.waldwissen.net/technik/holzernte/maschinen/wsl_helikoptersaege/index_ENAnd Christmas Jones was the worst and most unbelievable character in any Bond Movie EVER.

author: Ducttape
author_rank: Regular Contributor
timestamp: December 14, 2018, 03:47:59 pm
content: I guess they just assume that any nature lover strolling along nearby would run in terror away from the danger zone, assuming they're not hearing impaired.

author: Wan Huang Luo
author_rank: Regular Contributor
timestamp: December 14, 2018, 11:51:20 pm
content: Quote from: Ducttape on December 14, 2018, 03:47:59 pmany nature lover in the flight path of those blades would be trespassing on the power company’s right of way.

author: KL27x
author_rank: Super Contributor
timestamp: December 15, 2018, 12:25:23 am
content: QuoteExplosive bolts?QuoteHelicopters are used to carry tanks and such. And they always seem to use a really long cable/net when carrying stuff. The cargo is always danging way below the copter. I imagine it's to make it safer to take off and land.

author: beanflying
author_rank: Super Contributor
timestamp: December 15, 2018, 12:42:58 am
content: Generally not 20-30m below a light chopperIf you look at the sky crane or any of the twin rotor heavy lift choppers they are a very different beast to the ones used with these saws even then loads under flight are kept as close as possible to the heli then winched down when needed.I have flown one of my model choppers (3kg) with a cord suspended load under it (sub 1000g) getting going in any direction was fine it was the slowing down and stopping/reversing direction where it all got a bit hairy the load overshot then reversed before you had a chance to catch up if you were doing any sort of speed or were rough on the sticks (low speed was the key).If you are travelling a bit hard with 500kg of saw under you and you need to stop in a hurry or get stopped in a hurry it's going to get ugly no matter how good the pilot is. These guys btw have amazing skills

author: KL27x
author_rank: Super Contributor
timestamp: December 15, 2018, 12:55:34 am
content: I wonder though, if the cable is too short, the load might swing around in a greater arc. And certainly at a greater frequency with a shorter period. And stopping fast would do no good at all if the load and the rotors met paths or otherwise this made it difficult to control the aircraft? If you are radio controlling from the ground, that's a bit different than being in a vehicle that is rocking around because the shorter pendulum is swinging around more quickly?If the load is hanging far down, at least it is easy to go up - the opposite direction from the ground! Maybe?Since the beginning of time, seeing helicopters on TV carry stuff hanging way below, I figured there was something to it. There has to be some good reason for the danger I always imagined of forgetting what you're carrying and dragging the cargo into a tree or a power line.

author: beanflying
author_rank: Super Contributor
timestamp: December 15, 2018, 01:20:49 am
content: Shorter arc does get you a faster pendulum but also a lower potential energy. It's the KE = 0.5 x mass x Velocity^2that seems to be the issue to bring back into balance or change direction.Another part of the issue is the ratio of the suspended mass to the chopper weight. Traditional pendulums have a fixed pivot point and in the case of a light heli this won't be the case as it will get maneuvered (relative to the ground) by it's load on change in speed or direction. Controlling or damping the response is the key.