Chris Lord October 31, 2018

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In all the gyroplanes I have flown the rotor rpm takes care of itself once I am airborne and unless I am performing a flight maneuver that unloads the rotor;
the rotor will maintain flight rpm.
Sure, and if one has normal control of the rotor disc angle of attack, rrpm can be maintained in level flight with steady power. We all know this.

However, I don't believe that N198LT was flying normally in its last moments.
If the rotor disc had been flattened out (or nearly so) as I suspect, then level flight was very difficult at best, if not impossible.

I'd say that N198LT was in an involuntary descent, as Chris certainly wouldn't have have chosen to pleasure fly below legal minimum altitude over congestion.
While N198LT was in descent, flight rrpm was maintained (even with rotor braking), but at some point Chris could not safely descend further.
He may have hesitated at that altitude (i.e., 150 feet) by hauling back on the stick, and unloaded the rotor beyond the ability to restart it.


If I was fighting to keep the cyclic from going full forward as you postulate I don't know how I would slow down.

In my opinion I would not slow down by reducing power.
If the rotorhead was firmly forward as Phil described because of the trim reversal, what else is left but to reduce power?
That's what Phil had to do.

Regards,
Kolibri
 
Kolibri;n1141771 said:
Sure, and if one has normal control of the rotor disc angle of attack, rrpm can be maintained in level flight with steady power. We all know this.

However, I don't believe that N198LT was flying normally in its last moments.
If the rotor disc had been flattened out as I suspect, then level flight was very difficult at best, if not impossible.

I'd say that N198LT was in an involuntary descent, as Chris certainly wouldn't have have chosen to pleasure fly below legal minimum altitude over congestion.
While N198LT was in descent, flight rrpm was maintained (even with rotor braking), but at some point Chris could not safely descend further.
He may have hesitated at that altitude (i.e., 150 feet) by hauling back on the stick, and unloaded the rotor beyond the ability to restart it.



If the rotorhead was firmly forward as Phil described because of the trim reversal, what else is left but to reduce power?
That's what Phil had to do.

Regards,
Kolibri

In a Cavalon Rotor RPM takes care of itself unless I do something to unload the rotor. I do not need to do anything to maintain Rotor RPM.

In a Cavalon "hauling back on the stick" (aft cyclic?) in a descent will load the rotor and increase rotor RPM rather than decrease it.

If the cyclic was trimmed full forward as you postulate because somehow the trim inputs were reversed and there was so much pressure in the system that the two of them could not manage enough back stick to stay below VNE and Chris had not figured out how to correct the problem he would have flown into the ground at high speed. In my opinion the throttle would only control the rate of descent and not the indicated air speed or rotor RPM in your scenario.
 
HighAltitude;n1141763 said:
I just completed my MTO 2017 build on Monday and I took the time to run through some scenarios:

1. You cannot pre rotate in brake mode. There is a micro switch on the control shaft that prevents the prerotator from engaging until you move the stick back. The prerotator only engages when the stick is within range. Too far back or forward and prerotation stops. There is also a pressure switch to prevent prerotation with any pressure in the system. You must have the stick in the correct position AND no pressure in the system so you cannot prerotate in brake mode. You can learn it with engine off and key on. I don't understand the comment that it is not understood and involves guessing.


2. Switching to brake on takeoff roll. The pressure switch is set at about 2 bars. It will allow pre rotation at 2 bars or less but at that low pressure there is no braking pressure and the stick is easily pulled back. This is likely what happened to Phil. The PIC may have put it in brake mode but didn't build pressure. If he was trimming on climb out, it was poor technique.

2. Nothing happens immediately and suddenly when you engage brake mode in flight. The "Brake" position is really "Brake Armed". You have to take a second action to apply the brake. Rather than asking "Can you prerotate in brake mode?" the question should be "If a student engaged brake mode in flight, what would happen?". You do not fall out of the sky, nor does the stick go full forward with maximum force. Absolutely nothing happens. You would never know it was in brake mode if you never needed aft trim during your flight. Until you take the second step and build pressure use the trim switch, you wouldn't know the switch was in brake mode. If and when you trim aft in flight you will start to feel forward stick pressure when trimming aft. Again, with the engine off, it can easily be simulated. I imagine that if I pulsed aft trim in flight and the result was more forward pressure instead of less, I would notice it and probably bump the trim again. It would get slightly heavier and responding the opposite of what I intended so I imagine that I would try forward trim. I hope I would not panic and hold the aft trim button until stick forces required two hands but I can see how that scenario would cause confusion. However, a student could/should be taught not to mess with any trims during take off. Level off and then set trim. I will practice today in the hanger with engine off by switching to brake mode and then applying aft trim to get a feel for it and practice switching back to flight mode to feel the instant release of forward stick forces.

I have a brand new MTO sitting here that I know very well having just built it so if anyone wants me to test other scenarios that I may have not covered above, I would be happy to run through them in an effort to keep us all safer. I encourage everyone with an autogyro to sit in the seat, flip on power without starting the engine, and run through the scenarios that I did. I have a much better understanding of what to expect. We are all here to learn and help each other.

I'm sorry but this post is both confused, misleading and ultimately contradictory.

You absolutely CAN pre-rotate in brake mode and you say so yourself having told everyone in point 1 that you can't! That is misleading, in the context of what we are trying to explain dangerous and proves the point I was trying to make initially. People are confused on the issue.

SO TO BE CLEAR YOU CAN PRE-ROTATE IN BRAKE MODE.

The point I was making had nothing to do with the stick position - and therefore the micro switch has no effect on the issue I was describing.

Your own point 2 contradicts your point 1.

Regards point 3. Is nothing about selecting the BRAKE mode in flight and everything to do with the fact you think you are in FLIGHT mode because the switch has been selected incorrectly from take off.

The confusion comes like this....

You have just built a brand new MTO 2017 and at some point you perhaps do some flying with an instructor or maybe you read these forums. The question is made about the BRAKE / FLIGHT switch and the answer is given "no you can not pre-rotate in brake mode". So now for ever and a day you are flying around in the belief that you can not do what you absolutely can do! So when it happens why do you look? You didn't even think it could happen never mind what the function of it happening actually are!!

YOU CAN PRE-ROTATE in BRAKE mode. 100% I've been sat in an aircraft that has done just that. Am I dumb I didn't figure it out in the air? Perhaps. Was that where my thinking was? No because when I did a check ride for the aircraft it was never mentioned. The POH didn't mention and in my case [perhaps in this accident too??] I was a passenger until it got too much for the pilot flying. So you get handed a poor situation. Yes you can fix as you describe by simply dumping trim pressure BUT that is not what your brain is telling you is wrong. You expectation is that it is something else causing an issue and you want to get on the ground. That working out well depends on where and how you fly i.e. airmanship not flying over congested areas etc.

Once again to be clear. Pilots are generally casual with the BRAKE/FLIGHT switch. In so far that they are happy to switch from one mode to the next without it being part of a planned "checklist" style action or point. Indeed you can find YouTube footage of the accident pilot and his use of this switch and it is clear that it is not part of a lining up or departure fixed process.

The issue I had was [in my opinion] was caused because the pilot had flicked modes prior to lining up, got delayed and went into "auto-pilot" and flicked the switch again without actually reading or focused on what he was doing. With system pressure low - because it is very common with many Auto-Gyro Calidus and Calavon pilots to relieve stick forces to trim fully forward [i.e. dump any rearward trim pressure] once they go to FLIGHT mode. The problem is if distracted and they end up back in BRAKE mode you can pre-rotate.

Is it a problem? Well with good awareness arguably no more than having retractable undercarriage. BUT like all systems it is good to understand them and people in general believe you can not do something I know [and the system knows] is possible. Worse in a Cavalon both the switch and the pressure gauge are located in a position where the leg covers both so neither are visible with a casual scan.

Do I think it is relevant to the accident? Whilst I do not know what has caused the accident and will wait for the report I do feel it has the potential to have been a factor and I highlight to you guys here because of the confusion over what happens etc in the scenario.

Ultimately aircraft do not end in a fatal accident with experienced crew without reason and if you look at the time from take off to accident then something went wrong that wasn't engine related if you read the interim NTSB report so this is one possible control issue, which due to the unknown nature and my experience when it happened the only thing that stopped us from a similar situation was we were not flying over wires or a congested area. At 100ft AGL we still had not figured out our issues and had power lines been in our path we would have possibly hit them too.

Regards Rotor RPM as you all may know the rotor is in auto rotation and so RRPM is a function of loading. I closed the throttle in order to descend and maintain best glide speed and keep the disc loaded. Vance has explained the point well. I have a YouTube set of videos on gyroplane technique under my flying school name The Gyrocopter Flying Club for general flying stuff.

Any issue I would have had in the landing phase - had it come to that - would have been the fact it would have been a downwind landing and in a field. Turns were not going to be accurate and we had few options with the initial height. It is likely had we had to land the aircraft may have been damaged but I was confident we would likely have walked away. However in the grand scheme I was happy to take that given the situation moments before.

Please don't get confused with the issue. The BRAKE/FLIGHT mode is not something that causes RRPM to decay because of the mode being BRAKE (other than if you genuinely do bunt and then its low g and not the rotor brake that is causal). Stick force is the issue and the fact the aircraft is in a state that has maximum forward stick and you are not only working as if there was no trimmer but also against the pneumatic system pressure forcing it the other way. All this while stressed and trying to figure what is happening. Its ok for a minute but as you get tired the stress increases for obvious reasons.

Ultimately regardless of its application to this accident it is worth knowing - fore warned etc.
 
Vance, you're the one repeatedly mentioning excessive speed and Vne, not me.
As I've consistently written, Chris's issue was trying to maintain altitude, and his speeds were not reported to be high.
He was not witnessed to have dived into the ground at anywhere near Vne.

While N198LT was in descent, flight rrpm was maintained (even with rotor braking), but at some point Chris could not safely descend further.
He may have hesitated at that altitude (i.e., 150 feet) by hauling back on the stick, and unloaded the rotor beyond the ability to restart it.
In a Cavalon "hauling back on the stick" (aft cyclic?) in a descent will load the rotor and increase rotor RPM rather than decrease it.

Yes, but only a little bit, and only momentarily.
The context of my description was that he "may have hesitated at that altitude" -- meaning somewhat arrested his descent, thus slowing his airspeed.
That would have unloaded his rotor, perhaps critically.


If the cyclic was trimmed full forward as you postulate because somehow the trim inputs were reversed and there was so much pressure in the system that the two of them could not manage enough back stick to stay below VNE and Chris had not figured out how to correct the problem he would have flown into the ground at high speed.
I disagree. His involuntary descent did not have to reach anywhere near Vne.
A control-induced descent into terrain could happen at many angles and speeds.
For example, one could mimic a locked cyclic at any descent angle, and fly it into the ground at any 50mph or Vne or anything in between.
The Cavalon which Phil described here nearly did so at Vg.


In my opinion the throttle would only control the rate of descent and not the indicated air speed or rotor RPM in your scenario.
Throttle does not affect airspeed? Never heard that one before.


______
Phil, thanks for your continued comments about all this.
Your experience may have been eerily similar to that of N198LT.
It is good for AutoGyro owners to be aware this issue, which can be much more than merely "
disquieting".

Assuming your student had not at the last moment noticed the BRAKE position and switched to FLIGHT:
Do you think you could have rounded out and flared for a normal landing, or would you have pancaked in at Vg?
It seems more like the latter, but I don't want to misread your account.


______
Agreed: In a descent, the rotor is loaded.
Agreed: Increasing angle of attack sufficiently for a vertical descent will load the rotor.
Agreed: In level flight with power, the rotor is loaded.

HOWEVER, where I think Chris got to was the rotor disk just below level flight AoA, and with the rotor brake actuated through reversed aft trim.
He had apparently slowed his descent with some aft cyclic, but hadn't enough to either vertically descend or mush in with power.

The witness report bears this out: very little airspeed at 300 feet, followed by a nose down fall at 150 feet.
Sounds like rotor rpm decay to me, via a combination of unloading the rotor while braking it.

Remember, with the rotorhead trimmed full forward, the brake is actuated.
Pulling back on the stick only forces the rear of the torque tube even harder against the rotor brake pad.

I think it an unwise design for a system to possibly allow the cyclic to act as a rotor brake.

Regards,
Kolibri
 
"Remember, with the rotorhead trimmed full forward, the brake is actuated.
Pulling back on the stick only forces the rear of the torque tube even harder against the rotor brake pad."


Kolibri, you are incorrect on the operation of the Autogyro rotor brake system! Pulling back on the stick simply moves the trim cylinder and removes the front brake pad from the system. Believe me, when we were doing tracking and balancing, I would have loved to be able to increase brake pressure by moving the stick. I don't take any comments on the net as gospel. I cross check for myself.

One brake pad is on the front of the rotor head and one is on the back. (Assuming that Chris was flying the current rotor head). Building pressure in the cylinder engages the rear pad and pushes the rotor forward to engage the front pad. Even the slightest rear pull on the stick pulls the rotor away front the front brake pad, cutting the brake force in half. Phil already verified through his experience that the rotor brake would not cause the RRPM to decay.


In the spirit of providing facts, I just did another test. I put it in brake mode and built pressure to 8 bars. Then I attached a scale to the stick and pulled it back. Anyone wanna guess what stick force is needed to oppose the rotor pressure? It's only adding 23 pounds to normal stick forces. (I say adding 23 pounds because someone here will undoubtedly try to tell me the forces in flight are different). DUH, but the full "runaway" trim adds 23 pounds to whatever normal in flight forces are there.

Any other tests that you guys want me to run?

stick pull 2.jpg
 

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Kolibri;n1141778 said:
Throttle does not affect airspeed? Never heard that one before.

As Langewiesche succinctly put it, "The stick is the speed control" and "The real elevator is your throttle".
"If you hold the stick in a certain position, forward or backward, you thereby force the airplane to fly at a certain speed; a correctly behaved airplane with then fly at that certain speed regardless of the amount of power used. If you feed it a lot of power, it will climb at that speed; if you feed it less power, it will fly level at that speed. If you cut the power entirely, it will glide at that speed."
 
HighAltitude;n1141782 said:
"Remember, with the rotorhead trimmed full forward, the brake is actuated.
Pulling back on the stick only forces the rear of the torque tube even harder against the rotor brake pad."


Kolibri, you are incorrect on the operation of the Autogyro rotor brake system! Pulling back on the stick simply moves the trim cylinder and removes the front brake pad from the system. Believe me, when we were doing tracking and balancing, I would have loved to be able to increase brake pressure by moving the stick. I don't take any comments on the net as gospel. I cross check for myself.

One brake pad is on the front of the rotor head and one is on the back. (Assuming that Chris was flying the current rotor head). Building pressure in the cylinder engages the rear pad and pushes the rotor forward to engage the front pad. Even the slightest rear pull on the stick pulls the rotor away front the front brake pad, cutting the brake force in half. Phil already verified through his experience that the rotor brake would not cause the RRPM to decay.


In the spirit of providing facts, I just did another test. I put it in brake mode and built pressure to 8 bars. Then I attached a scale to the stick and pulled it back. Anyone wanna guess what stick force is needed to oppose the rotor pressure? It's only adding 23 pounds to normal stick forces. (I say adding 23 pounds because someone here will undoubtedly try to tell me the forces in flight are different). DUH, but the full "runaway" trim adds 23 pounds to whatever normal in flight forces are there.



Thank you for taking the time and making the effort to quantify the force Tim.

I feel it is useful to quantify force required and facts are more useful than fantasy.

I am not able to see in the picture how far aft you were pulling the stick.

I was wondering if the force increased as the cyclic is moved full aft at full pressure.

Have fun my friend.

Hope to fly with you again.
 
So we accept that you can pre-rotate with the aircraft in brake mode. Regarding stick force it would need to be rotors running, per g and of course in a Cavalon.

yes you could round out to land and the rotor brake element is not relevant.
 
Kolibri;n1141778 said:
Vance, you're the one repeatedly mentioning excessive speed and Vne, not me.
As I've consistently written, Chris's issue was trying to maintain altitude, and his speeds were not reported to be high.



I disagree. His involuntary descent did not have to reach anywhere near Vne.
A control-induced descent into terrain could happen at many angles and speeds.
For example, one could mimic a locked cyclic at any descent angle, and fly it into the ground at any 50mph or Vne or anything in between.
The Cavalon which Phil described here nearly did so at Vg.



Throttle does not affect airspeed? Never heard that one before.

Agreed: In a descent, the rotor is loaded.
Agreed: Increasing angle of attack sufficiently for a vertical descent will load the rotor.
Agreed: In level flight with power, the rotor is loaded.

HOWEVER, where I think Chris got to was the rotor disk just below level flight AoA, and with the rotor brake actuated through reversed aft trim.
He had apparently slowed his descent with some aft cyclic, but hadn't enough to either vertically descend or mush in with power.

The witness report bears this out: very little airspeed at 300 feet, followed by a nose down fall at 150 feet.
Sounds like rotor rpm decay to me, via a combination of unloading the rotor while braking it.

Remember, with the rotorhead trimmed full forward, the brake is actuated.
Pulling back on the stick only forces the rear of the torque tube even harder against the rotor brake pad.

I think it an unwise design for a system to possibly allow the cyclic to act as a rotor brake.

Regards,
Kolibri

In my opinion if the cyclic in a Cavalon was jammed full forward the aircraft would exceed VNE at any throttle setting.

In my opinion Kolibri's hypothesis that you can slow a Cavalon down with the cyclic jammed full forward by reducing the throttle is demonstrative of his lack of understanding of how a gyroplane flies.

I feel Kolibri's understanding of managing rotor rpm is sufficiently divergent to preclude communication.

I was reluctant to let this go because of a concern for this misinformation causing a safety issue.

I see now it gives Kolibri an opportunity to expand the misunderstandings as though it was an actual discussion.
 
As Langewiesche succinctly put it, "If you hold the stick in a certain position, forward or backward, you thereby force the airplane to fly at a certain speed; a correctly behaved airplane with then fly at that certain speed regardless of the amount of power used. If you feed it a lot of power, it will climb at that speed; if you feed it less power, it will fly level at that speed. If you cut the power entirely, it will glide at that speed."
Yep, true, Tyger, and I've read his book often.
Langewiesche is speaking of a
"correctly behaved airplane" which N198LT arguably was not.

If Chris could have remained level from a flattened (or nearly so) rotor disk (i.e., without sufficient AoA for level flight) by simply adding power, he'd have done so.
Conversely, he may have been more concerned with bunting over by adding power. (Phil mentioned this as his concern.)



___________
Kolibri, you are incorrect on the operation of the Autogyro rotor brake system! Pulling back on the stick simply moves the trim cylinder and removes the front brake pad from the system. Believe me, when we were doing tracking and balancing, I would have loved to be able to increase brake pressure by moving the stick. I don't take any comments on the net as gospel. I cross check for myself.

One brake pad is on the front of the rotor head and one is on the back. (Assuming that Chris was flying the current rotor head). Building pressure in the cylinder engages the rear pad and pushes the rotor forward to engage the front pad. Even the slightest rear pull on the stick pulls the rotor away [from] the front brake pad, cutting the brake force in half.
High Altitude, I don't know if N198LT had the 1 or 2 pad rotor brake.
On the older single rear pad system, when the pitch trim arm moves up, it pushes the rotorhead forward while simultaneously engaging the rotor brake. This is indisputable.
It does so even in the 2 pad rotor brake (for the rear pad).



Phil already verified through his experience that the rotor brake would not cause the RRPM to decay.
Not quite. What he wrote was:

On the BRAKE/FLIGHT point. Rotor RPMs were not significantly affected but that would be an impression rather than an absolute recollection.
Since he checked the bearing rotor bearing temp (RBT) gauge, it seems he had at least a subconscious cue to reduced rotor rpm.

Ultimately the friction material and surface area are insignificant verse the aerodynamic forces at play.
And I agreed with this, as he was then in a sufficiently steep descent which would have maintained flight rrpm even with the brake engaged.
However, with what little aft cyclic one can muster, descent would have been retarded, and thus airspeed, and thus rrpm.
At that point, the engage rotor brake would have more noticeably slowed down rrpm.


In the spirit of providing facts, I just did another test. I put it in brake mode and built pressure to 8 bars. Then I attached a scale to the stick and pulled it back. Anyone wanna guess what stick force is needed to oppose the rotor pressure? It's only adding 23 pounds to normal stick forces. (I say adding 23 pounds because someone here will undoubtedly try to tell me the forces in flight are different). DUH, but the full "runaway" trim adds 23 pounds to whatever normal in flight forces are there.
You may want to ask Phil if the two-handed stick effort required to keep him from bunting over felt like only 23 pounds.
Things are different in the air with a live rotor system.
Meanwhile, I applaud your spirit of inquiry and experimentation.

Regards,
Kolibri
 
In my opinion if the cyclic in a Cavalon was jammed full forward the aircraft would exceed VNE at any throttle setting.
With a high enough beginning altitude, I'd agree.
But, he did not start that high, and from witness reports we know that he did not make a continuous dive into the ground, much less at Vne.


In my opinion Kolibri's hypothesis that you can slow a Cavalon down with the cyclic jammed full forward by reducing the throttle is demonstrative of his lack of understanding of how a gyroplane flies.
Selective reading of my posts, Vance. As I stipulated, Chris seemed to have some aft cyclic ability, although not enough:

HOWEVER, where I think Chris got to was the rotor disk just below level flight AoA, and with the rotor brake actuated through reversed aft trim.
He had apparently slowed his descent with some aft cyclic, but hadn't enough to either vertically descend or mush in with power.

I feel Kolibri's understanding of managing rotor rpm is sufficiently divergent to preclude communication.

I was reluctant to let this go because of a concern for this misinformation causing a safety issue.

I see now it gives Kolibri an opportunity to expand the misunderstandings as though it was an actual discussion.
You have the oddest mental "lens" with me, apparently configured to assume that I must be incorrect in something that I post.
You readily misunderstand me, and then use that as a straw man to accuse me of error. I should start a file with excerpts.


However, you are the one who pooh-poohed my theory from page 1, and countered with your claim that forward trim forces would be easily overcome in BRAKE mode.
As Phil described, they were very difficult to resist even with both hands on the cyclic.
 
As Langewiesche succinctly put it, "The stick is the speed control" and "The real elevator is your throttle".


Adding throttle adds wind to an airfoil which results in lift.

A good example is a powered parachute which flies at a constant speed regardless of throttle position.

At full throttle, it climbs at approx 26 mph and at closed throttle, it glides down at approx 26 mph.
 
Mac, as I wrote, "If Chris could have remained level from a flattened (or nearly so) rotor disk (i.e., without sufficient AoA for level flight) by simply adding power, he'd have done so."


________
Speaking of AutoGyro rotor rpms, the MTO2017 Manual lists "Normal Range/Green Arc" as 200-550 rrpm.
200 rrpm seems very low for flight rrpm. Shouldn't it be something like 300 rrpm?
I've never heard of a 2-place gyro with 8.4m or 8.8m (27.6' or 28.9') rotor diameters being continuously flown <275rrpm, and certainly not at 200.



M2017 rrpms.png
 
If AutoGyro is sticking with their FLIGHT/BRAKE system, I think it'd be a good idea to concentrate together all rotor related gauges and switches for an easy scan.

Currently they are spread about the panel, and some are not readily visible (as Phil mentioned):


Worse in a Cavalon both the switch and the pressure gauge are located in a position where the leg covers both so neither are visible with a casual scan.





Cavalon panel.png



Cavalon panel list.png
 
"So we accept that you can pre-rotate with the aircraft in brake mode." My definition of brake mode is gyro is sitting with 8 bars clamping the brake and forward pressure on the stick. My definition of parked with the brake applied to the rotor was the basis of my comment regarding not being able to prerotate in brake mode.

Phil, Yes, there is another possibility that a pilot could switch to flight mode and back to brake mode before starting the rotors spinning. I hadn't thought of that and wonder why anyone would do it but that is absolutely possibility. I couldn't figure out why you were so passionate about it by putting it in caps. I am thinking through the checklist while idling on the numbers: hold stick forward - switch to flight mode - bring the stick back slightly to engage the micro switch - push the prerotate button - etc - etc. It seems foreign to me how switching back to brake mode would ever work its way into that sequence but it is absolutely possible. I would imagine that it could occur if the sequence was interrupted by a distraction. Thanks for adding a scenario that I never imagined. I learn every day and thank you for opening my eyes to another scenario. I think I will edit my checklist to check flight mode before releasing the brake to begin my roll.

Vance, my hand holding the scale is just out of the picture. The pressure rises from 8 bar to 9 bar at full aft stick. I was alone so I had to pull back the stick and take a photo. I am a student as you know. I do these tests to build knowledge of possible scenarios I might encounter in my gyro. If I could just command that damn string better and let go of my "step on the ball" FW training I would a happy pilot. I seem to be "stepping on the string" frequently.
 
Cavalon panel-4.jpeg


Circled in yellow are all the rotor and trim gauges. The bottom two are obscured by pilot and passenger legs.
Who does that make sense to?
In my opinion, these related and important instruments should all be clumped together.



___________
If I could just command that damn string better and let go of my "step on the ball" FW training I would a happy pilot. I seem to be "stepping on the string" frequently.
High Altitude, perhaps try "stepping on the head of the snake" (which is pointing at the correct foot of rudder pedal).
/ requires left rudder.
\ requires right rudder.

And, as I posted earlier, I applaud your spirit of inquiry and experimentation.



___________
Is it [the FLIGHT/BRAKE switch] a problem? Well with good awareness arguably no more than having retractable undercarriage.
Phil, I must respectfully disagree with what I see as your over-simplistic and inaccurate analogy.
It's not as if the AutoGyro's rotor brake system is activated by a stand-alone switch, like a retrac switch -- not connected to anything else.
Unfortunately, it's connected with and integral to the trim system, both electrically and mechanically.
I've not seen anything like this in aviation.

It's akin to an airplane's retrac gear operation being slaved to the flaps switch, with the same motor operating both systems.

Regards,
Kolibri
 
Just to be clear on the accident itself I'm not trying to pre judge events, I'm sure the NTSB will report when ready. I just wanted to highlight the facts around the BRAKE/FLIGHT switch because there was/is clearly confusion or assumption where I had some experience / facts. Take all of it or none of it as you see fit but being in the wrong mode is easily done and assuming human nature in the USA isn't going to vary too much from human nature in the UK and it is certain that once you guys fly Auto-Gyro product more you guys will find the same issues sooner or later. The process around the use of the BRAKE/FLIGHT switch is very poor and I include myself in that until I had the issue I described and now I am very disciplined only to switch once lined up and the next step is pre-rotating.

Indeed here are some YouTube clips of the accident pilot at Oskosh 2013 in a Calidus and you can see how experienced pilots have inconsistency with the use of the BRAKE/FLIGHT mode. In this clip he is lined up on the active and the time from switching to flight to pre-rotation is what? 5 seconds. But in clip 2 he is waiting off the active runway and it takes around 30 seconds in flight mode before pre-rotation. I've done the same thing and for sure it is one area that can snag you.

1 -
https://youtu.be/5LEEGKpP0wk

2-
https://youtu.be/V3lC0Y1QBro

Again to reiterate I'm not suggesting this is any definitive cause but it is a potential snag and having a good process with that Brake/flight switch will keep you safe.

One of the biggest snags with gyroplanes is the widely held belief that some how you "fly like a gyro pilot". How many times have you heard that? It is utter nonsense. You fly like a pilot of an aircraft and usually the "fly like a gyro pilot" usually involves some short cut or other flight mode that ignores the decades of good airmanship other forms of aviation have built on the accidents of others. I hate that phrase and usually anyone using it has limited aviation experience outside of a gyroplane. There are no new ways to get hurt in an aircraft.

To pick up on some points raised. Kolibri you have mentioned rotor RPM quite a few times so I want to clarify my own point. When I answered your question about did RRPMs change I was being too absolute. I don't know if they moved the odd 10, 20 RRPMs and so I gave the answer I did. However they did not fall significantly that I was worried falling RRPMs would be our downfall. The rotor brake is insignificant in its force verse the aero forces so I think you can move on from the rotor brake being a cause of any accident IMO.

If this played any factor then it will be simply a combination of confusion about what the issues are, a very uncomfortable feeling to continue the flight with the stick forces [and they are significant to be troubling] and then the rest is down to terrain / area and available place to put down. It would not have been an issue to have made some form of round out. If you believe that control restriction is such to have even prevented that then my No.1 place to look would as per my photo I attached initially.

On the ergonomics / cockpit layout. Yes I think it is an issue worthy of some attention but this isn't an Auto-Gyro bashing session. I think they make some decent aircraft on the whole and if you are aware of the snags [rear seat and rear stick in a 2017 Sport? That is a definite gotcha at some point] then for the most part they are solid aircraft.

If there is a wider issue then it is very often aligned to the general sport aviation market place and some of the people that exploit that market. If some of these issues are not discussed its because nobody wants to be the one to stick a head above the wall and make a comment that some way down the line means they miss out on ten bucks worth of business. In a way its pitiful but for sure that is the way it is.
 
I don't know if they moved the odd 10, 20 RRPMs and so I gave the answer I did.
However they did not fall significantly that I was worried falling RRPMs would be our downfall.

Right, and since you were in constant descent for an urgent landing, I'd concur that the rotor brake hadn't been an RRPM issue for you.

The rotor brake is insignificant in its force verse the aero forces so I think you can move on from the rotor brake being a cause of any accident IMO.
I'll have to differ here with you in regards to N198LT, which was not in a constant, steady descent (which would have maintained RRPM).
A witness reported that he had very little airspeed, and may have nearly ceased forward flight at 150 feet. The aero forces would have been less then.
At that moment, rotor braking may have been enough to slow RRPM below flight minimums, say 275-300 RRPM.
He did nose over then, which I cannot easily imagine without unloaded rotor. It may have even been a bunt over (power push over, PPO).

Finally, I wonder if something electrical malfunctioned in the trim system.
If the FLIGHT/BRAKE switch shorted out, it may have been rapidly going back and forth from FLIGHT to BRAKE, etc.
That would have been too much of a bizarre problem to chase down in a minute or two over population.



One of the biggest snags with gyroplanes is the widely held belief that some how you "fly like a gyro pilot". How many times have you heard that? It is utter nonsense. You fly like a pilot of an aircraft and usually the "fly like a gyro pilot" usually involves some short cut or other flight mode that ignores the decades of good airmanship other forms of aviation have built on the accidents of others. I hate that phrase and usually anyone using it has limited aviation experience outside of a gyroplane. There are no new ways to get hurt in an aircraft.
Indeed, Hear, Hear!

Thanks for your comments, Phil, safe flying!

Regards,
Kolibri
 
Philbennett;n1141818 said:
Just to be clear on the accident itself I'm not trying to pre judge events, I'm sure the NTSB will report when ready. I just wanted to highlight the facts around the BRAKE/FLIGHT switch because there was/is clearly confusion or assumption where I had some experience / facts. Take all of it or none of it as you see fit but being in the wrong mode is easily done and assuming human nature in the USA isn't going to vary too much from human nature in the UK and it is certain that once you guys fly Auto-Gyro product more you guys will find the same issues sooner or later. The process around the use of the BRAKE/FLIGHT switch is very poor and I include myself in that until I had the issue I described and now I am very disciplined only to switch once lined up and the next step is pre-rotating.
Indeed here are some YouTube clips of the accident pilot at Oskosh 2013 in a Calidus and you can see how experienced pilots have inconsistency with the use of the BRAKE/FLIGHT mode. In this clip he is lined up on the active and the time from switching to flight to pre-rotation is what? 5 seconds. But in clip 2 he is waiting off the active runway and it takes around 30 seconds in flight mode before pre-rotation. I've done the same thing and for sure it is one area that can snag you.
1 -
https://youtu.be/5LEEGKpP0wk
2-
https://youtu.be/V3lC0Y1QBro
Again to reiterate I'm not suggesting this is any definitive cause but it is a potential snag and having a good process with that Brake/flight switch will keep you safe.


One of the biggest snags with gyroplanes is the widely held belief that some how you "fly like a gyro pilot". How many times have you heard that? It is utter nonsense. You fly like a pilot of an aircraft and usually the "fly like a gyro pilot" usually involves some short cut or other flight mode that ignores the decades of good airmanship other forms of aviation have built on the accidents of others. I hate that phrase and usually anyone using it has limited aviation experience outside of a gyroplane. There are no new ways to get hurt in an aircraft.

To pick up on some points raised. Kolibri you have mentioned rotor RPM quite a few times so I want to clarify my own point. When I answered your question about did RRPMs change I was being too absolute. I don't know if they moved the odd 10, 20 RRPMs and so I gave the answer I did. However they did not fall significantly that I was worried falling RRPMs would be our downfall. The rotor brake is insignificant in its force verse the aero forces so I think you can move on from the rotor brake being a cause of any accident IMO.

If this played any factor then it will be simply a combination of confusion about what the issues are, a very uncomfortable feeling to continue the flight with the stick forces [and they are significant to be troubling] and then the rest is down to terrain / area and available place to put down. It would not have been an issue to have made some form of round out. If you believe that control restriction is such to have even prevented that then my No.1 place to look would as per my photo I attached initially.

If there is a wider issue then it is very often aligned to the general sport aviation market place and some of the people that exploit that market. If some of these issues are not discussed its because nobody wants to be the one to stick a head above the wall and make a comment that some way down the line means they miss out on ten bucks worth of business. In a way its pitiful but for sure that is the way it is.

Thank you for your thoughtful input Phil.

As a flight instructor you have experienced more pilot errors than most people can make in a lifetime or even imagine.

As a flight instructor when I say "fly like a gyroplane pilot" I am trying to communicate that a gyroplane may not respond well to fixed wing habits and protocol.

I typical fixed wing pilot lands at more than 50kts of indicated air speed.

Most gyroplane pilots don't do well touching down at 50kts.

In a takeoff roll in a fixed wing the controls are often centered and the takeoff roll is started.

A gyroplane pilot likes to have some rotor rpm before commencing the takeoff roll.

In my experience most fixed wing pilots rotate at some specific airspeed and command the rotation.

In my opinion a good gyroplane pilot allows the gyroplane fly when it is ready at some combination of indicated airspeed and rotor rpm and commanding it to fly is in my opinion poor airmanship.

In the USA a gyroplane pilot is specifically instructed to avoid the flow of fixed wing traffic.

I feel a gyroplane pilot needs to be more aware of fixed wing traffic because of the speed differential and because fixed wing pilot are looking for wings and find rotorcraft difficult to see.

I have not attached the negative connotation to "fly like a gyroplane pilot" that you have Phil. To me being considered a gyroplane pilot is a high honor.

I watched both videos and did not see any confusion or inconsistencies about switching from brake to flight and back to brake again.

Chris is flying in a very chaotic environment and needs to be ready to go when he hears from the air boss.
What am I missing Phil?

I don't know any flight instructors in the USA who would not make people aware of what they thought was a problem because of a fear of missing ten dollars down the road. Several CFIs in the USA have been very vocal about what they feel are issues.

I feel you may be confusing professional behavior with greed.

I have flown and instructed in many different makes and models of gyroplanes and they all have strengths and weaknesses. I don’t see the value in focusing on the negative. I do not see a particular manufacturer currently over represented in gyroplane accidents and the majority of accidents in the USA are pilot error.

Most of my clients will be taking their proficiency check ride in a gyroplane different than what I trained them in. I do not find a challenge transitioning them into the check ride aircraft. When they use the appropriate check lists the transition has been relatively easy.
 
What I got out of Phil's comment was that some gyro pilots seem to believe that they are less vulnerable or nearly immune to certain flight aspects.
As I mentioned in another thread regarding how to make a gyro approach during very energetic winds/turbulence, it's not like gyroplanes reinvented aeronautics.
I had recommended adding half the gust factor to one's short final airspeed, and was thus accused of flying my gyro like a FW by someone who was
trying to defend his making a nearly vertical descent landing during variable winds of 30G38 with ground rotors off the hangars.



___________
If you believe that control restriction is such to have even prevented that then my No.1 place to look would as per my photo I attached initially.
Thanks, Phil, and I'd like to understand that area better. I've saved your photo and rotated it to try comprehend its proper orientation.
Could you please explain "which way is up" in it, and also post a couple of other photos of the various cable brackets?
I want to correctly envision how the parts move inside the cockpit. Thank you for more photos when you've the time.



___________
Regarding the MTO2017 hangar test of trim air pressure and stick forces, I think the disparity between what Phil experienced
(having to fight with both hands
"troubling" forces) and High Altitude's 23.4 lbs can easily be explained by the strong aerodynamic force
of Phil's nearly tucking rotor. Once he had added full "aft" trim, level flight was no longer possible, and he was in an uncontrolled descent.
Fighting that and avoiding a bunt over (even at engine idle!) naturally required more than 23.4 pounds of stick force.

In fact, the experience was so dicey that Phil discouraged the experimentation of it.


Back to High Altitude's test, here was the sequence as I understand it:


BRAKE mode on, trim pressure now reversed
pitch trim cylinder fully pressurized by max AFT trim (which moves the rotorhead in reverse, i.e., forward) reaching 8 bar on the gauge
pulling cyclic fully back (which increases trim pressure from 8 bar to 9 bar)

My point here is that aft physical force on the cyclic invariably adds pressure to the trim cylinder, which forces the actuator even harder
against the rotorhead and the brake. Thus, aft cyclic in that mode acts like a rotor handbrake.
While such may not be significant while in descent, I think it would definitely become an issue between the roundout and flare.

Jim Vanek told me that he once tried the experiment of pulling the M912 rotor brake on short final.
He described the descent as immediately steepening in pitch, and the roundout and flare barely possible.
And, the Sport Copter M912 rotor brake is not as effective as even AutoGyro's single pad system.

After such confusing involuntary loss of altitude, I suspect that Chris Lord had essentially "rounded out" at that 150 feet in hesitation over congestion.
If so, then his aft cyclic force would have then created max rotor braking pressure, simultaneously with a reduction in airspeed to overcome rotor braking.


Show me any aircraft, past or present, where flipping a switch in-flight reverses the pitch trim.
AutoGyro only designed it that way to "cleverly" have the air trim perform double-duty as the rotor brake.
Those systems must be separated and kept independent of each other, both electrically and mechanically.

For the sake of gyro safety, I strongly urge AutoGyro GmbH to redesign their air trim and rotor brake system to avoid the possibility -- by a pilot merely flipping
a single switch to the wrong position -- of such a dangerous trim force reversal. That such a wonky system exists in a type certified aircraft is inexcusable.

Regards,
Kolibri
 
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