North Queensland Gyro accident

[Vance]

Ever try a power failure or power chop at the top of a zoom in a Dom or other “CLT" (LTL) gyro? Probably not - you are still alive! The suddenly reduced nose-up prop thrust will cause the nose of a LTL to tuck badly, and this could cause the rotor to "precess stall" violently – even initiate a buntover! And “chopping power” is exactly what many people presume is the way to avoid a buntover if you think one might happen – reduce power! In a LTL that does not work – it’s dangerous!! Even in a true CLT, that might not work, because the lack of any nose up pitch help from reducing power does not prevent the reducing Gs slowing the rotor, during a “push over” the top of a zoom. (In a HTL, it can be helpful to suddenly reduce power at the top of a zoom because it provides a nose-up pitch reaction that helps to avoid a precession stall and might alleviate some of the reducing rotor load.) The statement that a "CLT or "LTL" cannot buntover is, IMHO, dangerously misleading. And, many people just refer to any "high seater" as CLT! - when they are very likely to be LTL – pitches rapidly nose-down (the destabilizing direction) upon a sudden reduction in power – power chop or engine failure!.

Conversely, a moderately HTL can be made to be just as insensitive to buntovers as “CLT” or LTL might STATICALLY be presumed to be - in a HTL case you would call this a "PPO". (True, a CLT or LTL cannot “PPO” - but that is only terminology semantics – they can still buntover!) What all too many people are presuming – yes including Jean Fourcade - is that only the STATIC moments on a gyro are the determining factors in the ability to buntover – or not! The terminology of a “lever” or “loss of rotor drag with a HTL” are all limiting and often misleading STATIC concepts – easy to describe and visualize, but incomplete! Tim, your links are very good and impressive treatises in STATIC principles. They introduce us to some basic principles involved. But the DYNAMIC properties of the aircraft are also a BIG part of the whole picture – most people do not understand the word “DYNAMIC”, much less allow it might be important to any purely STATIC based presumptions. Limiting our presumptions to just the more readily understood STATIC concepts limits our advances and the acceptance – at least in the U.S. – of higher order concepts that work extremely well too! Any aircraft needs inherent DYNAMIC damping. For a gyro airframe, this can only come from the HS. It is DYNAMIC damping that prevents PIO. It also can prevent buntovers (or “PPO”). It is DYNAMIC damping that softens or slows turbulence so that it is less (or no) problem for the pilot. STATIC moments are only part of the story!

For instance, the Magni is probably somewhat HTL – maybe a lot! Ask Connie how she handled the extreme turbulence on takeoff and landing practice with me last year at Mentone (Rochester). These were terrible gusty winds, even cross winds on landings behind a large cluster of trees on touchdown. We made high speed go arounds and climbs through the rotors behind those trees! Returning back to Mentone in heavy turbulence at higher cruise speeds. From this and all our Magni flight and training experience, I would not readily presume or easily accept that this Australian accident was a buntover or PPO. Connie had no problems doing all the flying (well not every landing!) – and we made it back to Mentone without even elevated adrenaline!

What Fourcade and others are not considering – IMHO – is the buntover and turbulence insensitivity that a very large and far aft mounted HS provides as an airframe pitch “DYNAMIC DAMPER”. The dynamic damper “extends” the static stability range – less prone to buntover. The highly effective airframe “DYNAMIC damper” prevents short period airframe oscillation overshoot that can incite PIO. The DYNAMIC damper provides quick and accurate re-alignment of the airframe pitch attitude to any change in flight path from wind or pilot input – highly stabilizing! - There has never been a reported or confirmed case of buntover (PPO) or PIO in a Magni. (None that I know of reported in ELAs or MT03s either!) There are over 500 Magnis currently flying with most pilots flying over 200 hours a year in some of the worst wind conditions we see anyone fly in! Many Magni gyros regularly cruise at 100+ mph! Lots of ELAs and MT03s also flying!

I have purposefully tried to buntover my Magni M16 – level flight hard forward quick stick jab to a fixed or free stick at 90 mph – flight testing to validate some of the ASTM standard stability requirements. When I jabbed the cyclic forward more than about 2 inches at higher airspeeds, the rotor teeter hits its stops and creates very forceful stick “bumps” that discourage further excessive “jab” – might have to be suicidal to push through that! – it does quickly pitch down and builds airspeeds, and with the stick fixed – wild ride! - then recovers back to level flight itself within about 2 -1/2 phugoid (long-period) cycles. I’m still here. (I don’t propose anyone doing this – we teach people not to do this in any gyro – I hope! Just proving a point! Gee, the Magni is HTL – it must buntover from all these STATIC descriptions!!!!! Why doesn’t it – DYNAMIC DAMPING? - Or did it this time? Let’s see the accident indications.)

We have low time Magni people flying a lot in really gusty winds at high speeds all the time! I have been flying with a non-pilot introductory student (he was doing the flying) when struck by a thunderstorm gust front – very severe drops and rises. Very noticeable sudden nose drops and rises. My arm flew every which way, so it was the student who flew through this - first reactively gripping the cyclic, and then letting go (I think I do remember him screaming!) Afterwards, I told him to let me do the flying and let’s get further away from the storm! You would have a hard time convincing me, and any other Magni flier that I know, that the cause of this Australian accident would be turbulence! This accident has no confirmation of what caused it yet. I would ask people not to assume it was a buntover when they automatically presume that any HTL will buntover.

What can buntover any gyro MIGHT be a “push over the top of a zoom”. We should be teaching people to not do this – I hope! Any gyro, HTL, CLT, LTL, and maybe even strongly DYNAMICALLY damped gyros might buntover from the top of a zoom!!! I have not wanted to try that in a Magni either! But, I doubt any experienced gyro flier would do that either!

Gyros can hit the ground violently for any number of reasons. I don’t want to vilify any instructors, but are all gyro pilots respecting the HV (Height Velocity) curve? Slow gyro flight has especially surprising height loss upon sudden engine loss or even temporary power reduction. A steep nose-up full power and slow climb out is much worse. The sudden slowing airspeed and the pilot reaction to shove the nose forward upon a sudden power reduction rapidly loses rotor RPM – RRPM that does not easily recover when full load is restored on the rotor immediately thereafter – too much sudden air volume for the RRPM. Worst case, this can be an in-flight “rotor flap”. Best case is the gyro drops like a rock until the rotor can recover its normal 1G RRPM. If the ground is too close, the pilot might not be able to raise the nose to prevent a steep impact with the ground. If the pilot is able to raise the nose to level attitude, the rotor might still not be able to slow the rapid descent and the gyro hits hard flat! I know from experience that even a sudden but short engine chop at lower heights from a steep full power and slow climb can so suddenly slow the gyro and rotor as to make it drop long and hard like a rock. (I had a student who loved to pull the nose up and climb steeply just after leaving the ground – my admonitions about engine failure did not deter him from trying it to see if I was right. He zoom climbed after lift-off, chopped power – I jammed power back in and the nose forward and down - and was just able to get the gyro level and somewhat slowed vertically before we hit flat – even at full power! Luckily we suffered only a little prop tip damage! (I also washed out that student right there!) (This was the only “push over the top of a zoom” that I will ever do again – not even at altitude!)

I don’t disagree that turbulence would readily cause loss of control in the Magni – just have never seen any Magni flier even think they were even close to scary loss of control on landing or at any time! - at least if they had been properly taught to land in those conditions and worked up to the worse conditions. My newest, and lowest time new Magni flier (maybe 100 hours now) just told me yesterday how much fun he had practicing landings in 15-25 mph turbulence the other day!!! – his worse winds so far. I can’t imagine a high time Magni flier getting into trouble in the wind – but this Australian pilot did have a wind gust roll-over on the ground once – Is training complete – holding some airspeed safety margin in wind conditions? Expecting rotors behind obstacles, etc.? Respecting the HV curve?

Mechanical failure could cause a loss of control – this gyro had major repairs last year – were those properly supervised and inspected by someone who is familiar with the assembly of the Magni? [This is one advantage I see in our American practice of building kits! – repairs and maintenance are done per original Assembly procedures! – or at least they know enough to ask! There was a Magni fatality in South Africa a few years back and (I believe) the CAA there reported improper assembly (controls) of a “parts” kit the owner had purchased used – without proper factory supervision of the re-assembly!]

Things happen, but let’s see if ASRA can determine a cause – then we may all learn something – yes, including me or Jean Fourcade or all of us! Yes, I am defending the Magni - I didn’t want to have to, but misleading presumptions that HTL is all bad and CLT (and especially LTL) is only good, are, IMHO, dangerously misleading and stifle safer understanding, practices and advancements in gyroplane safety. I am really wanting to expand our understanding, practices; and, sometimes mis-placed confidences beyond the simplistic STATIC realm. But, for now, let’s just let ASRA do its job.

Thanks, Greg Gremminger – U.S. Magni Gyro srl representative. But, in no way are my comments to be construed as the comments of Magni Gyro srl. I think Magni would just want to leave its safety record make the stability points.

Hello Greg,

I practice engine outs regularly on climb out with my low thrust line gyroplane and it is a non event. I will try to recognize what it is you are trying to describe. I recognize that survival a few hundred times is not an indication of safety.

I am an NTSB enthusiast and I am not able to find an example of this reducing power in a Dominator and ending up dead.

All of my instructors taught not to do zoom climbs.

My lessons had to wait until we had wind conditions below 10kts so I could separate environmental inputs from pilot input.

My instructors never ran me into a thunderstorm. They taught me about weather conditions and how to find out what is going on.

I feel it is not best practice to do something dangerous and suggest that survival indicates that it was actually safe.

I appreciate all you have done in an attempt to make gyroplanes safer and clearly Magni makes a good gyroplane.

I am not able to imagine the compelling reason the Magni pilots you describe as flying in terrible conditions have for not waiting for better weather.

I would be grateful if you would back your fervor for high thrust line gyroplanes down enough so you do not feel compelled to make things up about how bad other designs are.

Thank you, Vance

 

[gyrogreg]

Choice A or B

Choice A or B

Greg, our atmosphere is an ocean of air that is but rarely still. Gusts or wind shears can come from any direction; horizontal, vertical and anywhere in between.

Imagine you encountered a gust so severe that airspeed momentarily dropped to zero. Airliners on approach have stalled and crashed in severe wind shear.

Which gyro would you rather be in during such a hypothetical situation?

(A) A HTL gyro with mammoth horizontal stabilizer mounted below the propeller slipstream.

(B) A true CLT gyro with barely adequate horizontal stabilizer.

The above is meant in no way to be speculation about the Oz crash.

Chuck - my choice would be (A):

I had flown a LTL Dominator in turbulent conditions often. It flew very comfortably through strong wind turbulence low over the Missouri hills at 90 - 100 mph. Hands on and hands off it took care of the turbulence without a care! BUT, when I would reduce power to start a decent to the airport at that same airspeed, it got very uncomfortable. So much so that, at lower power, where the nose is not held so artificially high - CG so far forward of the RTV - I would cruise flight to over the airport at cruise power without descending, and then reduce power to idle for a vertical descent. What I learned is that the higher airspeed presented so much nose down STATICALLY destabilizing airframe moment that the reduced LTL prop thrust did not compensate – hold the nose up to be statically stable. The Dom was much more stable at lower airspeeds - where the nose-down aerodynamic moments did not statically destabilize it so much, or at high power where the LTL overpowered the airframe aerodynamic static destabilizing moments - even at high airspeeds. But, for a LTL, low power at high airspeeds is less statically stable – and possibly even statically unstable at higher airspeeds with all the airframe nose-down aerodynamic moments. And the short moment arm on the HS did not provide much adequate pitch damping to make it comfortable. At high airspeed and low power, the LTL config can get marginally dynamically stable – indicating approaching static instability – little or no static restoring CG-RTV moment.

I also experimented with sudden power reductions - at 70 mph level flight, upon sudden power reduction to idle dropped the nose quickly and radically - I estimated about 15 degrees. I believe it was only my experienced sudden aft stick reaction that prevented a precession stall - spindle was not allowed tilt forward the full 15 degrees with the airframe. This was a shocker, because like many, I believed at the time that the Dom configuration had no faults. I almost ate the runway!!! Never reduced power that quickly in the Dom before - and I stopped flying over 70 mph also - afraid the engine might quit - uncommanded! I think any Dom pilot would confirm that when you make power changes you have to make a cyclic pitch adjustment – if you don’t want the nose to raise or drop quickly. Even if a gyro does have a severe pitch attitude reaction to power change, it is very helpful if it is damped to prevent it from being so fast that it could excite the pilot into over-control, or precess tall the rotor. About 1 year later, after getting much abuse from many about my concerns with sudden power reductions on an LTL – the Adler accident happened in Colorado. This was before I ever even considered flying a Magni – they looked too HTL to me!!!! Maybe the jury is still out on the Adler accident, maybe it was mediation, but the accident debris indicated a buntover or precession stall. I remember your words back then, Chuck. To Carl Schneider’s concern about promoting LTL, you replied to Carl – “Carl, I love ya, but too much of a good thing is not good!”. Carl and I had previously discussed my concerns with a large power reduction at high airspeed. I asked him if he had ever chopped his throttle at high airspeed in his tall “skeeter”. He said he never did that because the nose dropped so severely it did not feel good. Of course, if you never chop the power or the engine never quits, this concern with LTL might be mute.

I also have over 1500 hours in my High Command - which was not so severely LTL, but still had the similar but lesser flight characteristics. In both the Dom and my "High Command", I learned not to fly at high airspeed at low power in turbulence. I learned to be ready for a sudden uncommanded power stoppage.

In the Magni, we regularly fly at any power level at any allowed airspeed - Vne: 115 mph. Me or a student can suddenly change power with not near as much airframe attitude change - and the change is not sudden - large "DYNAMIC DAMPER". What it does do is roll a bit quickly with power (torque) change - but pitch changes are slow and not severe - not nearly as severe as on the Dom or High Command. I believe the difference is the HS DYNAMIC stabilizer. The Magni HS is large, aerodynamically efficient, and on a long moment arm. The Dom and High Command both had a Dom "T" - Tail. (The Dom and High Command did not roll so much on a power change - a benefit of the tall tail that I do respect, but it sure did allow the airframe to pitch rapidly - very little pitch DYNAMIC damping - especially without the full blast of propwash upon reduced engine power.)

So - Hmmmmm - Yes I choose (A) above. But, I do also say that the Dom LTL was an important learning element, and did improve gyroplane stability safety and appreciation greatly. But, it still has stability issues in a high speed glide and with sudden power changes.

Choice (B) CLT does not assure it doesn't have statically destabilizing - nose-down - aerodynamic moments at higher airspeeds - so its CG-RTV moment might not be a RESTORING static moment. CLT doesn’t count for much is something else is causing the gyro to fly with the RTV forward of the CG. If the CG-RTV static moment might be a divergent - nose-down - moment, you would certainly need a HS to add adequate DYNAMIC damping to prevent a tendency to buntover. So, what we don't really know on Choice (B) is how destabilizing are the static aerodynamic airframe moments, and how good of a DYNAMIC damper the HS is. But, even a statically barely "adequate" HS might be a good dynamic damper if it is located on a long tail arm. It might then “extend” the static margin to help avoid buntovers too!

The STATIC balancing effect of a HS is proportional to the length of the tail moment arm (from CG). The DYNAMIC damping effect of the same size HS is proportional to the square of the moment arm. So, even moving the same HS back further could compensate for some destabilizing airframe moments (prop thrustline or airframe, windscreen, wheels, etc. Even statically, the whole picture is not just HTL or CLT or LTL - the whole static picture includes the other aerodynamic moments on the airframe that become very significant at higher airspeeds. Since almost all gyros have destabilizing, nose-down aerodynamic moments at higher airspeeds, it probably takes a decent nose-lifting HS to even statically compensate somewhat.

I would not go so far as to say that any gyro could withstand such severe gusts, vertical or horizontal, as you suggest are out there. But, the configuration, A or B above, I would rather be in would be (A). That is not to say I might not prefer a pure CLT with the same Dynamic stab as a Magni – but I don’t know it would be any safer or fly better in severe turbulence. I do believe that in such sever turbulence I would rather have more dynamic damping than a small, barely “adequate” HS might provide. But, move that small HS way back, and I might re-consider.

Chuck, I don’t think you have ever flown in a Magni. My invite is still available – if we can get together. I hope it would be a very gusty day – that’s when the Magni really shines! A couple of us are thinking of flying down to Bensen Days – maybe then?

- Thanks, Greg Gremminger

 

[All_In]

Now I'm getting confused!
I'm used to having a formula that at least come close to real life = for any aircraft.
This is starting to sound like personal basis is getting in the way.
I guess the only way for me to know is experience flying all of these with a parachute at altitude? Is there no other way to really no the effects of HTL, CLT, LTL all of the time?

 

[gyrogreg]

Hi Vance, I don’t dispute much of what you say below – we keep learning and I’m not always proud of the flying I’ve done - Greg

Hello Greg,
I practice engine outs regularly on climb out with my low thrust line gyroplane and it is a non event. I will try to recognize what it is you are trying to describe. I recognize that survival a few hundred times is not an indication of safety.

Good for you – practice makes perfect. How about the newbie that hasn’t honed the skill to adjust the cyclic pitch with power changes. How about a sudden unexpected, uncommanded power loss. What you are practicing is essential, but I bet you don’t chop power in a hard, nose-high, full power slow climb out too close to the runway. You’ve leaned better. But think about the newbies that read this. - Greg

I am an NTSB enthusiast and I am not able to find an example of this reducing power in a Dominator and ending up dead.

I commend what the Dominator and Earnie have done to improve stability awareness and understanding. The Dom configuration certainly reduces the chances of a buntover – because it might only happen upon a sudden engine stoppage at high airspeed. It certainly is more likely for a HTL without a good HS to buntover – it is almost always in the precarious condition. I’m just pointing out it can happen. The NTSB report on the Adler accident may suggest medication impairment – but the debris still suggested a buntover or precessions stall. - Greg

All of my instructors taught not to do zoom climbs.

Great! - Greg

My lessons had to wait until we had wind conditions below 10kts so I could separate environmental inputs from pilot input. .

That is a good idea. Even in the Magni the learning curve progresses quicker if we can start in milder wind conditions. But, many of my students have done a lot of their initial training in bad winds. Even in moderate turbulent conditions, new students, even those who have never flown anything, will be flying the Magni well within ½ hour – not landing, but flying at any airspeed! But, its easier to teach in light winds. - Greg

My instructors never ran me into a thunderstorm. They taught me about weather conditions and how to find out what is going on.

I do not like my decision making in this instance either. The student came to town specifically to see how it handled the winds. The thunderstorm was small and there was no anvil. We were at least 5 miles away and we were just looking for a bit more turbulence than the afternoon presented. We were surprised by the gust – and thought better of our decision immediately! Approaching the thunderstorm presented a lot of opportunity to talk about such things too! - Greg

I feel it is not best practice to do something dangerous and suggest that survival indicates that it was actually safe.

Screwed up on the T storm thing. Was over confident in the Dom when I chopped power – I call it ignorance of such things at that time. The buntover attempts were approached slowly with lesser and slower cyclic inputs – first without a fixed stick condition, and then to fixed stick – I was watching for the limits carefully. - Greg

I appreciate all you have done in an attempt to make gyroplanes safer and clearly Magni makes a good gyroplane. I am not able to imagine the compelling reason the Magni pilots you describe as flying in terrible conditions have for not waiting for better weather.

If it is safe, why not – turbulence , especially for heavier gyros like the Magni, should not be a big issue. - Greg

I would be grateful if you would back your fervor for high thrust line gyroplanes down enough so you do not feel compelled to make things up about how bad other designs are.

My fervor is for safer gyros too. Just pointing out technical misrepresentations that prevent even safer gyros. I wonder how a gyro with real CLT and CLD would perform with the other attributes of a Magni – big long tail, heavy efficient rotor, etc. Just pointing out that just the appearance of HTL does not mean a gyro is dangerous – the Magni is good proof of the opposite! Magni and some other European producers are expanding the safety and utility of gyros. I am just trying to get the U.S. to move in an improving direction too – I’m tired of unnecessary accidents and behind the power curve thinking that is limiting us – HTL is just a harmful paradigm. Not all of what I promote is just Magni. Magni also fervently requires good training as an essential element – even with the safest gyro in the world! - Greg

Thank you, Vance[/QUOTE]

 

[barnstorm2]

If you replace the word bunt with PPO,....

.

Yes, that is correct. A properly designed gyro that is CLT - LTL or with proper stablization can not PPO.

Boy Tim, I hate to jump in here before we have any indication of what the cause of this tragedy really was! I did expect that someone would jump to a premature presumption of PPO! .

Greg, I was not as clear in my post as I should have been. I was in NO WAY commenting on this accident. I was commenting on the post concerning 'bunt-overs' and gyroplane stability.

But, Tim, I cannot disagree more with your statement (presentation inference also) that a "CLT" or LTL cannot buntover. .....Ever try a power failure or power chop at the top of a zoom in a Dom or other “CLT" (LTL) gyro? Probably not - you are still alive! The suddenly reduced nose-up prop thrust will cause the nose of a LTL to tuck badly, and this could cause the rotor to "precess stall" violently – even initiate a buntover! And “chopping power” is exactly what many people presume is the way to avoid a buntover if you think one might happen – reduce power! ..... Tim, your links are very good and impressive treatises in STATIC principles. They introduce us to some basic principles involved. But the DYNAMIC properties of the aircraft are also a BIG part of the whole picture – ...... STATIC moments are only part of the story!

For instance, the Magni is probably somewhat HTL – maybe a lot! Ask Connie how she handled the extreme turbulence on takeoff and landing practice with me last year at Mentone (Rochester).....– and we made it back to Mentone without even elevated adrenaline!

.....- There has never been a reported or confirmed case of buntover (PPO) or PIO in a Magni. .

Greg, You might have missed my first post in this thread. I wanted to make it perfectly clear that what I was discussing was a Power Push Over and not any other kind of Bunt over.

I am strictly talking PPO not the other forms of bunt-overs such as the kind you described that involve cutting power and unloading the blades.

Please also note that I indicated that properly designed CLT - LTL gyros are not the only means to achieve PPO resistant designs but also properly designed stable machines (which in my mind means dynamically stable) but I did not wish to get into any further detail but rather use general statements.

I find it a challenge to educate a general audience in static stability and to try to fully explain both static and dynamic concepts often is too much to swallow. That why I put the link at the end of the presentation to the Google Video so that those interested in pursuing the topic could go on to a more detailed explanation that included both static and dynamic demonstrations.

When I was first making the presentation I had planned to add some dynamic stability concepts. Bassically, I was thinking about using your yard-stick visual example that you give during your Mentone Forum presentations* but as I worked on the presentation I found that it was getting too large with even what I had in it.

I will let Chuck talk about any references to his article that I posted.

As far as the Magni goes, I hold the gyroplane in the highest regard and would be highly surprised if one would PPO unless someone was extremely dead-set on doing so (pardon the pun). I always referr to the Magni as a highly stable and well designed gyroplane. If you search some of my posts to nubees on my recommendations for a safe, stable gyroplane I always try to include the Magni.

.
*The presentation you give shows divergence concepts I wanted to add as well.

 

[Murray Barker]

Gentlemen,(And Ladies) We seemed to have gone from a post advising of the death of one of our colleagues, to Magni bashing. Whilst I am the first to admit I am not a big fan of ANY HTL gyro this was certainly not the cause of Michael Howards death in his Magni two days ago.

As ASRA President I have been briefed on the outcome of the investigation and the main area of concern is a design characteristic that is also found on ELA gyro's.

As ASRA is not the only party involved in the investigation it is not possible for me to forward more information. Obviously we will advise of the outcome ASAP.

I know I am stating the obvious here but I implore all of you to thoroughly preflight your gyro before every flight and by that I mean EVERY SINGLE NUT AND BOLT.

 

[barnstorm2]

Gentlemen,(And Ladies) We seemed to have gone from a post advising of the death of one of our colleagues to Magni bashing. Whilst I am the first to admit I am not a big fan of ANY HTL gyro this was certainly not the cause of Michael Howards death in his Magni two days ago.
.

Murray,

I may be mis-reading something or may have missed something but I don't see any Magni-bashing here.

Things have certainly gotten a bit off topic here and I am partially to blame since I failed to express in my first posts that I was talking about general design styles and misconceptions and NOT THE ACCIDENT.

The Magni Autogyros are well designed machines with a fantastic safety record.

.

 

[bones]

As ASRA President I have been briefed on the outcome of the investigation and the main area of concern is a design characteristic that is also found on ELA gyro's.

The Ela I inspected in the hangar here has a "normal" set up in the area of concern, it appears it is only the Magni's

I know I am stating the obvious here but I implore all of you to thoroughly preflight your gyro before every flight and by that I mean EVERY SINGLE NUT AND BOLT.

 

[Gyro_Kai]

The Ela I inspected in the hangar here has a "normal" set up in the area of concern, it appears it is only the Magni's

Can you specify a bit more the "area of concern"?

Kai.

 

[Vance]

Hi Vance, I don’t dispute much of what you say below – we keep learning and I’m not always proud of the flying I’ve done - Greg

Hello Greg,

I am sorry you missed my point.

Good for you – practice makes perfect. How about the newbie that hasn’t honed the skill to adjust the cyclic pitch with power changes. How about a sudden unexpected, uncommanded power loss. What you are practicing is essential, but I bet you don’t chop power in a hard, nose-high, full power slow climb out too close to the runway. You’ve leaned better. But think about the newbies that read this. - Greg

I am a newbie Greg. I have less than 500 hours in rotorcraft.

I don’t climb out at slow airspeeds. I was taught to respect the height velocity curve. I do climb out at full power until I am about 300 feet agl. When I am practicing engine outs on takeoff I do cut the power gently most of the time to take it easier on the engine. Sometimes I just chop the power to get a more realistic representation of an engine out. I practice at all altitudes, even 10 feet off the runway.


I commend what the Dominator and Earnie have done to improve stability awareness and understanding. The Dom configuration certainly reduces the chances of a buntover – because it might only happen upon a sudden engine stoppage at high airspeed. It certainly is more likely for a HTL without a good HS to buntover – it is almost always in the precarious condition. I’m just pointing out it can happen. The NTSB report on the Adler accident may suggest medication impairment – but the debris still suggested a buntover or precessions stall. - Greg

It is my understanding that the worst thing you can do is reduce airspeed in a low altitude full power engine out. To suggest that having the nose come up is a good thing does not fit into my understanding of best practice for an engine out on takeoff. I feel I need airspeed to flair, why would I want to waste altitude slowing down and then speeding up again when the engine goes quiet?

I feel like you are really reaching here Greg, if the Dominator was as dangerous as you suggest they would litter the landscape. That is not how I read the reports. Great! - Greg

That is a good idea. Even in the Magni the learning curve progresses quicker if we can start in milder wind conditions. But, many of my students have done a lot of their initial training in bad winds. Even in moderate turbulent conditions, new students, even those who have never flown anything, will be flying the Magni well within ½ hour – not landing, but flying at any airspeed! But, its easier to teach in light winds. - Greg

Greg, Edna learned to fly my low thrust line gyroplane straight and level in ten minutes.

I do not like my decision making in this instance either. The student came to town specifically to see how it handled the winds. The thunderstorm was small and there was no anvil. We were at least 5 miles away and we were just looking for a bit more turbulence than the afternoon presented. We were surprised by the gust – and thought better of our decision immediately! Approaching the thunderstorm presented a lot of opportunity to talk about such things too! - Greg

Screwed up on the T storm thing. Was over confident in the Dom when I chopped power – I call it ignorance of such things at that time. The buntover attempts were approached slowly with lesser and slower cyclic inputs – first without a fixed stick condition, and then to fixed stick – I was watching for the limits carefully. - Greg

If it is safe, why not – turbulence , especially for heavier gyros like the Magni, should not be a big issue. - Greg

That is just my point Greg, in my opinion it is never safe to fly any aircraft in high wind conditions.

My fervor is for safer gyros too. Just pointing out technical misrepresentations that prevent even safer gyros. I wonder how a gyro with real CLT and CLD would perform with the other attributes of a Magni – big long tail, heavy efficient rotor, etc. Just pointing out that just the appearance of HTL does not mean a gyro is dangerous – the Magni is good proof of the opposite! Magni and some other European producers are expanding the safety and utility of gyros. I am just trying to get the U.S. to move in an improving direction too – I’m tired of unnecessary accidents and behind the power curve thinking that is limiting us – HTL is just a harmful paradigm. Not all of what I promote is just Magni. Magni also fervently requires good training as an essential element – even with the safest gyro in the world! - Greg

Thank you, Vance

[/QUOTE]

A gyroplane has crashed and a pilot is dead, I feel we need to learn as much as we can about it.

Saying things are safe does not make it so.

Saying other things are dangerous whether or not they are is not productive.

I do not want to enter a debate. I do not have the skill set for that.

Thank you, Vance

 

[Monk]

Always sad to hear the pasing of a fellow rotorhead.

 

[Tex~N~Oz]

I feel that perhaps I'm a bit of a culprit in this... I'm the one who immediately made statements about bunt-overs, etc... I honestly wasn't trying to lead the discussion into this as factual cause and didn't intend it taken that way. Nor did I intend to highlight the deficiencies of any manufacturers gyro.

My only goal was to gain information and I have done that. Following Tim O's gyrowiki I've come across some techinical writings by Chuck Beaty and I have to say this man is genius and I'd hand over a left arm to have just a touch of this man's knowledge in this field. All of this time I thought that rotor collapse was caused by a decreased rotor speed and lack of inertia. Now I understand it's a result of precession stall.
All this time I felt the problem could be countered by maintaining rotor RPM but obviously that's not the case at all.. I have to admit it's all a bit confusing.

 

[Chopper Reid]

Gents, a bit more patience is required before the findings can be released and they will be released ASAP.
The advice of "I know I am stating the obvious here but I implore all of you to thoroughly preflight your gyro before every flight and by that I mean EVERY SINGLE NUT AND BOLT. " says all that can be said at this point in time.

Please show patience !!

 

[Chopper Reid]

I feel that perhaps I'm a bit of a culprit in this... I'm the one who immediately made statements about bunt-overs, etc... I honestly wasn't trying to lead the discussion into this as factual cause and didn't intend it taken that way. Nor did I intend to highlight the deficiencies of any manufacturers gyro.

My only goal was to gain information and I have done that. Following Tim O's gyrowiki I've come across some techinical writings by Chuck Beaty and I have to say this man is genius and I'd hand over a left arm to have just a touch of this man's knowledge in this field. All of this time I thought that rotor collapse was caused by a decreased rotor speed and lack of inertia. Now I understand it's a result of precession stall.
All this time I felt the problem could be countered by maintaining rotor RPM but obviously that's not the case at all.. I have to admit it's all a bit confusing.

I'm not sure who Murray was alluding too but we all ask questions and learn, being a FW pilot you have a bit of catching up to do in the reading department as gyros are fairly complex due to different designs, different thrust heights and a plethora of other variables and probably, this topic is not the place to have this discussion due to a the tragic death thats taken place.

 

[gyrogreg]

ASRA on the case

ASRA on the case

Murray,

Thank you for your post. It is comforting to know that ASRA is involved so quickly, and that the organization has the resources and experience to do such an investigation. I think we are all over-anxious to find a cause of this accident - to help avoid any such in the future. A thorough and definitive root cause determination will be very constructive to safety in the world of gyroplanes. We always say we hope such a tragedy will not go in vain - we need to accept the one gift our deceased fellow aviator can still give ot all of us - improved knowledge that will keep us all safer.

If I can be of any help, please contact me. I probably have as much experience with Magni construction and flying as anyone outside of the Magni factory.

Thanks, Greg Gremminger

 

[geirove]

Boy Tim, I hate to jump in here before we have any indication of what the cause of this tragedy really was! I did expect that someone would jump to a premature presumption of PPO! But, Tim, I cannot disagree more with your statement (presentation inference also) that a "CLT" or LTL cannot buntover.

Greg:
I do not understand how you can endure all this CTL = Stable Gyro oversimplified "hammering". But please keep up the education, even though it does not seem to help. Problem probably is that most people here does not have the knowledge to understand the whole picture, but can relate to the oversimplified HTL, CTL, LTL "theory".

I said something about all this in another old thread here:

http://www.rotaryforum.com/forum/showthread.php?p=274938#post274938

Again Greg: Keep up the good work !


Pilot of HTL ELA 07.

Geir Ove
Norway.

 

[barnstorm2]

CTL = Stable Gyro oversimplified "hammering".
Geir Ove
Norway.

Geir, I am not sure what post(s) you are referring to but I don't see anyone saying that a CLT design is inherently stable nor people saying that a HTL machine is necessarily not stable.

Apples and oranges.

You can have an unstable CLT machine and a very stable HTL machine.

What I have seen is recommendations that people buy and fly stable gyroplanes and I certainly think that is good advise.

Any gyroplane that I would consider well designed would be static and dynamically stable and that includes HTL, CLT and LTL machines.

-> If you think that an unstable (static or dynamically) gyroplane design is good or provides some advantage I would certainly like to hear your 'theory' but you may want to start a new thread for it.


---------------------------------------------

Speaking of education. I think it can cause confusion to use the general term 'bunt'. Bunt includes PPO (power push over) and other forms of tip-overs (as described in Greg's post). However, when you cut out Gregs' description of non PPO bunts like you did in your quote you might mislead some people into thinking that a CLT gyroplane can PPO and that is not the case.

There is a great deal of information on how PPO can be prevented and CLT is only one method. HTL machines can be made 'virtually' PPO proof as well if a system is designed to counter act the thrust line offset.

References:



http://gyrowiki.com/GyroWiki/Common Terms.aspx

http://gyrowiki.com/Shared Document...CTID=0x0120001B8A4E515AAA624FBDD3EA16F1078C39

http://gyrowiki.com/GyroWiki/Glossary.aspx
Bunt-Over: Bunt

A sudden uncontrolled forward tumble about the pitch axis in a gyro; unrecoverable fatal. A bunt-over is a self-sustaining divergent nose-down pitching motion, accelerated and propagated by rapidly changing or diminishing balancing moments on the airframe. Typically, when the nose-down pitch of the airframe and/ or rotor disk reaches a certain point, the nose-down pitching self-perpetuates and accelerates (positive feedback) to result in a full forward tumble. “Power Push-Over is one form of a “Bunt-Over”, but not necessarily the only form of a bunt-over. A “Bunt-Over” is not necessarily a Power Push-Over. Without adequate gyroplane configuration design, a bunt-over can be initiated by wind gust, pilot over-reaction, or sudden power changes. See also PPO Power Push Over


.

 

[mceagle]

This accident thread has gone off topic and has degenerated into non-related discussion on PPO.
I will start a new thread under the Theory of Flight (Aerodynamics) heading.

 

[gyromike]

Good idea Tim (McClure).

Let's keep this one on topic, or even better let's wait for the ASRA report.

 

[Murray Barker]

Hello All, We are at the point of publishing an Airworthiness Directive in Australia for Magni gyro's. Thank you all for being patient but as you would expect we had to be sure of our facts.

The Magni is unique in a few area's of construction,one being the use of right AND left hand thread rod ends used in the control system vertical rods.
This system is also used in some brands of helicopters.
The main reason for this design I believe is ease of adjustment.

On the recent accident gyro it was found that one of the control rods was completely dislodged from the upper and lower rod end. No evidence of damage to the threads on either the rod end or the insert was found.The control rod was found loose at the impact site.

It was obvious to the investigators that the rod had unscrewed in flight rendering the gyro uncontrollable.

Obviously once the rod ends/lock nuts were loose and with the apparent lack of any locking type compound on the threads there was nothing to stop the control rod from completely unscrewing.

This is of course different when two right hand threads are used where if the control rod does become loose it will never detach if at least half the thread of each rod end is screwed into the control rod insert.

All Magni gyro's in Australia are now grounded pending the owner fitting a positive locking device on the control rods/rod ends.

We fully appreciate the excellent safety record of this brand of gyro and admit there are extenuating circumstances with the rod ends on the aircraft that crashed.

I will publish the AD on a separate thread and we will advise the Magni factory of our findings.

In the meantime I would appreciate if anyone you know that may not read this to be informed and make the inspection of this area of their gyro a priority at preflight.

Thanks,
Murray Barker,
Australian Sport Rotorcraft Association.