Dynamic rollover (almost)

choppergabor

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I was taught a 2 step technique. Slowly up on the collective applying pedal correction till light on the skids. Hold it there for a moment again checking pedal correction. Then continue slow up collective applying rudder correction.
Exactly Chuck!!! Right on!!! Until you have a light skid and the pedals are holding the heading there is no picking up. Thank you for that post. :)
 

Ken_Shea

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Chopper, no need to call me Sir, Karl is just fine.

Yeah, that was my thinking as well, every time someone calls me sir, that isn't just out of the military it indicates some underlying sarcasm.

There is little obvious in a couple seconds, while I certainly agree he should have never got into that attitude in the first place that ship has lots of power, he reacted and pulled it off, and likely learned something as well in the process. Who here will admit to having never been on a similiar edge.

Ken
 
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choppergabor

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Yeah, that was my thinking as well, every time someone calls me sir, that isn't just out of the military it indicates some underlying sarcasm.
Ken
Ken you obviously don't know me. When I want to be sarcastic I do have my way with words to do so. Don't read anything into my way of showing respect Sir! I do appreciate it. We can still add something positive to this thread if we concentrated on the content, and not trying to figure out "underlying" mystical messages and meanings. I am much simpler creature than that.:puke:
 

Ken_Shea

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Ken you obviously don't know me. When I want to be sarcastic I do have my way with words to do so. Don't read anything into my way of showing respect Sir! I do appreciate it. We can still add something positive to this thread if we concentrated on the content, and not trying to figure out "underlying" mystical messages and meanings. I am much simpler creature than that.:puke:

Don't need to know you, have seen hundreds just like you, BTW, I guess that decision would be up to me how I perceive what you say.
I would not be all proud of "When I want to be sarcastic I do have my way with words to do so."
I'll stick to my first ideas on your use of the word "Sir".
And
You might practice what you preach SIR, or is this forum like so many others, outsiders with only a couple post are to have no opinions that doesn't mesh with the high count posters.

Personally, I have had my fill of this forum already, way too many smart ass's, and I think you are one of them, SIR!

Now I am done, will move on, and good bye!
 

choppergabor

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Thank you for the valuable information and the wealth of knowledge you have contributed to my thread. We have learned so much from it. Please come back periodically and post again, just spread the knowledge so we can learn more. (Didn't take ya long to call me names now did it? I am still waiting for the refute of the content of my post rather than getting hung up on the fact I was using the word Sir....... It is quite a custom to do amongst real pilots addressing each other Captain or Sir when they communicate..... But you wouldn't know about that would you?..... Gee being polite gets me in trouble..... Wow you have really told me off..... I think I'll just stay inside today and won't go out in public I don't want them to see me like this!) So again I personally appreciate your contribution to my thread. It was really great to hear from you.
Cheers
the"one of the smart ass's"
 
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StanFoster

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Ken and Gabor- Hey....may I suggest tuning into the Olympics. There are some real exciting Curling competitions going on. Especially the Norwegians with the diamond patterned clown pants on.

My wife Barbara and I have actually enjoyed watching curling...instead of our heated dynamic rollover discussions that we get into everynight over supper.



Stan
 

choppergabor

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LOL Stan when I saw the Norwegian team come out I thought for a second it was half time in the Circus and time for the Clowns to entertain...... :)
 

Chuck Roberg

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This forum is sort of like the Olympics. Only the strong survive. :rolleyes:
 

dennisu

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RotoPlane

The throttle twist grip controls the FADEC as a fly-by-wire operation. The FADEC will hold the turbine at rated RPM until you change the twist grip setting. The collective only controls the collective.
 

Steve McGowan

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ThankYou,,,,,

ThankYou,,,,,

Thats the most intelligent statement I've read on the forum in a long time Chuck.. and Yes it's worth paying for

So many Pro's on the Forum that I'm just humbled to be allowed to
view and make a comment..

But in the real world,, They just need to stay they're asses on the porch.
 

Heron

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Now I am done, will move on, and good bye!
Make that a good bye . . . Sir! :D
Hey! just be a good number, we are not asking much of you!
Heron
 

helipaddy

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Any of you guys take off without the SAS engaged? flew a 222A that behaved really weird with the 2 helipilots off, was in a bit of a rush forgot to engage the helipilots and almost rolled it into a S61
 

brett s

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One of my CH-47 assignments in the Army was at the Maintenance Test Pilot course - we used to intentionally create various faults for the students to diagnose.

Among other things, we'd switch #1 & #2 AFCS/SAS (depending on C or D model) cannon plugs & unplug one system so it would really be "off" when they thought it was "on" per the switch position & master caution panel. That could be interesting with a student who was on the slow side...

The one that always got them every time was shutting off fuel on one engine right at touchdown - they'd never notice until they started to time the N1 spooldown per the checklist & it was already at zero.
 

Arnie Madsen

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Looking at the video I think its less than 2 seconds from when it would be apparent there was a problem and when the aircraft pulled free.

As he was already pulling collective before the problem was apparent, he would have had to be very quick to realise what was happening, and react to it before it pulled free.

The only person who truly knows what happend and what decisions were made is the guy who was on the controls. Its always easy to pull a pilot to pieces for his actions from the comfort of your computer chair with no knowledge of what was really happening.

Give the guy a break it was a 2 second event in someones life and it ended with no damage. It could easily happen to any of us, if and when it does I hope we are all lucky enough to have a similar outcome.
Karl.

My thinking was along the same line as yours. I have never flown a Cobra like the guy in the video . I also will never be a pilot for the Red Bull helicopter show.

That leaves me as a bystander trying to figure out what the pilot was doing at the time. Here is my best guess and in my own words:

Most of the Red Bull Show helicopters use a multi blade articulated rotor and if things go funny on light skids or wheels it can be a precursor to ground resonance and the best thing to do is pull collective and get off the ground.

I have no idea if that is what went through the pilots mind in that split second but I am willing to allow him that.

If he was a multi blade heli pilot his instinctive training would be to pull abrupt collective.

If he was a high time bush pilot accustomed to snagging skids on stumps he did the wrong thing.

My guess is he is a high time multi rotor pilot who thought he was entering ground resonance. Ground resonance cannot occur in the 2 blade Bell Cobras but that is beside the point.

I completely understood your post Karl. Thank you.

Arnie.
 

GyroDoug

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This forum is sort of like the Olympics. Only the strong survive. :rolleyes:
Amen to that!!! It's really too bad that so many people get offended so easily and get sidetracked so quickly. We seem to have a hard time staying on topic and let little "perceived" insults and "innuendo" take over and start battles. Most of the time people are not trying to offend other but those with thinner skins sure see offense, even when none was intended.

It does seem to be true, only those with a strong commitment to this sport are able to stay with it long enough to actually make it work for them. The good news is anyone can be that strong. It really is just a decision within each of us. Here's to being Strong!!!
 

Arnie Madsen

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A Hughes 269 on a perfect asphalt runway or a smooth grass turf could end up in a situation where down collective is wrong and up collective is correct if things go funny on lift-off.

Some folks think the suspension on the Hughes 269 was so that it could handle the abuses of the student pilot. That is only partly true.

Another reason for the shock absorbing suspension is to reduce the ground resonance tendencies of a three or more blade rotor system.

Do a study of Ground resonance and it will become clear.

Back to the original video in this thread. If the helicopter was a Hughes 269 / 300 and for whatever reason , the right rear skid remained solid on the ground when the heli was "light on the skids" things could go wrong pretty quick.

A fully articulated rotor allows each blade to hunt for the exact position it (the blade) wants to be most comfortable at. If one corner of one skid is on the ground and the other three points of the skid are off the ground the three blades will hunt for a position that will put them out of phase which puts the rotor system out of balance and the helicopter will self-destruct faster than dynamic roll over could ever do.

Soft suspension (Hughes 269) is designed to accommodate the possibility of the weight being on only one point of one skid and part of the design is to retard the onset of ground resonance. Especially as a trainer.

Bell 47's and Hiller12 trainers did not design any suspension into the landing gear because they are 2 blade rotors and ground resonance is not an issue.

When things do not feel right at light skids on a two blade rotor , down collective is usually correct.

If things do not feel right at light skids on a muliti blade rotor , up collective is usually correct.

A guy just has to remember what he is flying during the split second when things feel funny on liftoff. The Cobra pilot pulled collective in his split second decision. Pulled up some grass turf and was ok in the end.

Now everybody go back and watch the video again and notice how absolutely smooth that heli was once it was free of the ground. This was not a pilot who did not know how to stay in control after a wild 2 seconds.

Either fully on the ground or fully off the ground is best in any helicopter , to add to that remember how many blades are on the helicopter you are flying at that moment. Sometimes that moment is less than one second , so think fast.
 

choppergabor

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Arnie I have to disagree with your statement of "If things do not feel right at light skids on a multi blade rotor , up collective is usually correct" Up collective is never correct. You do not get into ground resonance on take off. It happens rather on landings due to bumping the heal of the skid sending a shock wave through the frame to the head. The multi bladed rotors do not have the wobbly movement of the two bladed rotor, that is why not prone to dynamic rollover. That lift of the advancing blade comes at only every 180 degrees so in between the next lift there is a lot of sinking and lifting again and that will tip the machine while 3 bladed Hughes will have 120 degrees between lifting pressure and makes it much less wobbly. We do fly the cabin on the 300 we still have the skid on the ground and the cabin is already hovering. Anything funny at that point roll off the throttle and lower the collective, according to the manufactures manual. The only time you pick up when at landing you do go into ground resonance. IF you still have the rotor RPM sufficient enough to pick up, if not roll off the throttle and lower collective. The ground resonance will seize if you disconnect the source of either forces. It's a wild ride tough. The skid dug into the asphalt and we felt like we were just riding the freaking mechanical bull after way too many beers :)
 

RotoPlane

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RotoPlane

The throttle twist grip controls the FADEC as a fly-by-wire operation. The FADEC will hold the turbine at rated RPM until you change the twist grip setting. The collective only controls the collective.
This new high-tech stuff is scary for me…..there is just something disquieting about circuits replacing mechanical…….you know….old school stuff ;). Thanks Dennis!
 
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