Forums: Skydiving: Incidents:
Premature from a helicopter

 

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billeisele  (A 5643)

Dec 6, 2013, 8:24 PM
Post #101 of 107 (1243 views)
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Re: [onelawndart] Premature from a helicopter [In reply to] Can't Post

onelawndart wrote:
this is what happens when a chopper loses it's tail rotor with no forward airspeed.

http://iloveskydiving.org/...ng-helicopter-crash/


RichM  (D 100226)

Dec 8, 2013, 2:44 PM
Post #102 of 107 (901 views)
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Re: [onelawndart] Premature from a helicopter [In reply to] Can't Post

This possibly should have its own thread? But very interesting all the same. It looked like the rate of yaw remained stable which I wasn't expecting, and the rate of descent also remained stable although the vertical speed looked like an uncomfortable landing speed. I'm not a pilot of any description but am interested to know if that vertical speed could have been reduced without increasing the yaw? Or possibly reduced just before touch down? Thanks in advanec


onelawndart  (No License)

Dec 8, 2013, 3:17 PM
Post #103 of 107 (880 views)
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Re: [RichM] Premature from a helicopter [In reply to] Can't Post

the helicopter is turning (yaw) because of the gyroscopic effect of the spinning main rotor.. the only thing that can stop that turn is enough wind against the vertical stabilizer. it can be extremely difficult to build forward speed once in a spin. there is another situation that may also be playing a role on the rapid descent. a helicopter's blades needs clean air in order to gain lift, once it is falling through it's own dirty "prop wash", it has no air to "grab". the blades are basically caught in it's own "burble". the only way to remedy this situation is to push the cyclic forward and maneuver the heli, and blades back into clean air, which may have been impossible while stuck in the turn. this is why a heli should always have some forward airspeed. in answer to your question about that looking like an uncomfortable landing speed... a heli needs forward speed to land without power, or to make a running landing (no tail rotor)... the pilot must basically "flare" the heli the same as you do your chute... straight down = zero flare.. although you can't see the crash, i am sure it was ugly..


(This post was edited by onelawndart on Dec 8, 2013, 3:30 PM)


vitriol  (C License)

Dec 8, 2013, 8:07 PM
Post #104 of 107 (786 views)
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Re: [onelawndart] Premature from a helicopter [In reply to] Can't Post

I don't know who told you that, but pretty much all your post is nonsense.

And I'm not saying this only to you, but even if this is not the best source of information, dz.com is read by a lot of people, people don't always confirm if what they read here is correct and true. People make choices based on what they read here.

If you don't really know the subject, sometimes it's better not to say anything than to offer nonsense as facts. \rant

onelawndart wrote:
the helicopter is turning (yaw) because of the gyroscopic effect of the spinning main rotor..


The tail rotor helps counter the TORQUE effect from the engine turning the main rotor baldes. The gyroscopic effect is entirely different.

onelawndart wrote:
the only thing that can stop that turn is enough wind against the vertical stabilizer.


Actually it is very easy: you put the engine at idle speed, wich engages the freewheeling unit. The main rotor blades now turn freely and arent engaged to the transmission/engine, thus not producing any torque/yaw.


onelawndart wrote:
it can be extremely difficult to build forward speed once in a spin.
It's pretty easy, student pilots learn to do it.

onelawndart wrote:
a helicopter's blades needs clean air in order to gain lift, once it is falling through it's own dirty "prop wash", it has no air to "grab". the blades are basically caught in it's own "burble". the only way to remedy this situation is to push the cyclic forward and maneuver the heli, and blades back into clean air, which may have been impossible while stuck in the turn.

It's called vortex ring state, and happens when you fly into your own vortex, at the same speed as them. In that case you just have to lower the collective to stop creating vortexes, and move away.


onelawndart wrote:
this is why a heli should always have some forward airspeed.


You do know that helicopters hover don't you??


onelawndart  (No License)

Dec 8, 2013, 8:48 PM
Post #105 of 107 (762 views)
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Re: [vitriol] Premature from a helicopter [In reply to] Can't Post

dude you are so clueless.. i am not sure where to start..

1. even if you throw the transmission into idle the gyroscopic force of the BLADES will keep you spinning. who told you otherwise? as a matter of fact, the engine is turning in a whole other direction.
2.
Quote:
Actually it is very easy: you put the engine at idle speed, wich engages the freewheeling unit. The main rotor blades now turn freely and arent engaged to the transmission/engine, thus not producing any torque/yaw.
this is asinine.. are you suggesting just dropping the collective? then what? spin into the ground? spin into the jumpers under you? the emergency procedure for loss of a tail rotor is to gain or (preferably) maintain enough speed to help straighten the craft and perform a "running" landing.
3. helicopter students definitely do NOT practice gaining speed while in a spin. loss of tail rotor procedures are done at a few feet off the ground. how far are you going to go in 7 feet?
4. helicopters only hover for landing in most cases. when possible we make a running takeoff just in case there is a problem, we have the forward speed to flare and land safely. when we come in to land we never come straight down.. Google "helicopter height/velocity diagram", maybe wikipedia can explain it to you.

I agree with you that
Quote:
If you don't really know the subject, sometimes it's better not to say anything than to offer nonsense as facts. \rant
Have you considered taking your own advice?


vitriol  (C License)

Dec 10, 2013, 9:40 PM
Post #106 of 107 (540 views)
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Re: [onelawndart] Premature from a helicopter [In reply to] Can't Post

onelawndart wrote:
dude you are so clueless.. i am not sure where to start..

1. even if you throw the transmission into idle the gyroscopic force of the BLADES will keep you spinning. who told you otherwise? as a matter of fact, the engine is turning in a whole other direction.

As I explained before the gyroscopic force is irrelevent in this case. My instructors told me otherwise, I've experienced it myself many times, and if that's not enough, Manufacturers flight manuals tell me otherwise. Here's a direct quote:

Bell 206 Jet Ranger HB-XYA
Version 21.09.2012 7/16

BELL 206 B III - EMERGENCY PROCEDURES


TAIL ROTOR CONTROL FAILURE
 Complete Loss of Thrust
- Close throttle
- Enter autorotation
- Maintain minimum airspeed 50 knots (58 mph)

onelawndart wrote:
2.
Quote:
Actually it is very easy: you put the engine at idle speed, wich engages the freewheeling unit. The main rotor blades now turn freely and arent engaged to the transmission/engine, thus not producing any torque/yaw.
this is asinine.. are you suggesting just dropping the collective? then what? spin into the ground? spin into the jumpers under you? the emergency procedure for loss of a tail rotor is to gain or (preferably) maintain enough speed to help straighten the craft and perform a "running" landing.

I'm suggesting to put the engine to idle or just put the collective down, thus regaining control of the helicopter, autorotate, then land. You might be assuming a fixed pitch failure, but it's clearly not the case here.

onelawndart wrote:
3. helicopter students definitely do NOT practice gaining speed while in a spin. loss of tail rotor procedures are done at a few feet off the ground. how far are you going to go in 7 feet?


Actually from 7 feet you should be able to land right on the spot after a t/r failure if you follow the procedure. And if you have a good formation you do practice recovering from a spin as a student. The first few times from altitude, and them from a few feet.


onelawndart wrote:
4. helicopters only hover for landing in most cases. when possible we make a running takeoff just in case there is a problem, we have the forward speed to flare and land safely. when we come in to land we never come straight down.. Google "helicopter height/velocity diagram", maybe wikipedia can explain it to you.


Helicopters are used for many different kind of jobs. Often, you do take off or land vertically, and sometimes to do the job you do have to hover for many hours in a day. For skydiving operations it is often possible to have the jumpers exit from a hover. Its fun, and it's not dangerous if the helicopter has the performance to do it.

onelawndart wrote:
I agree with you that
Quote:
If you don't really know the subject, sometimes it's better not to say anything than to offer nonsense as facts. \rant
Have you considered taking your own advice?

Well, if you are actually flying helicopters, and believe all you wrote, I strongly advise you to talk to a competent instructor before you fly again. If you don't have anyone to ask I'd be happy to talk to you by PM. Seriously, if you actually fly helicopters you show a serious and dangerous lack of comprehension of many very basic principles. I'm not bragging, but I've been working as a pilot for many years and have teached this many times, I do know what I'm talking about.

Enough hijacking this thread, but again, you can contact me by pm if you want to discuss this further.


onelawndart  (No License)

Dec 11, 2013, 9:28 AM
Post #107 of 107 (443 views)
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Re: [vitriol] Premature from a helicopter [In reply to] Can't Post

dude.. if you are an instructor.. find a new job. you are liable to hurt someone. none of your "replies" validates anything you are trying to say. are you actually licensed? i find it hard to believe. i'm done here. pm me if you want.


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