Gyro Warning System

All_In

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PS:
When I hear of new inventions like this I cannot help but think of the future improvements to any device.
Once it is fully tested you could easily couple it to autopilot and take over when the newbie is going to crash.
No more flying behind the power curve you could force her to parallel the runway gaining speed.
Heck, I could program an MCU to take off herself. But where would the fun in that be?
 

fara

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PS:
When I hear of new inventions like this I cannot help but think of the future improvements to any device.
Once it is fully tested you could easily couple it to autopilot and take over when the newbie is going to crash.
No more flying behind the power curve you could force her to parallel the runway gaining speed.
Heck, I could program an MCU to take off herself. But where would the fun in that be?

A human pilot should always be able to over-power and thus override any autopilot or similar device. At the end of the day you want a trained pilot to make the best decision not the machine. This is just another tool to give pilot warning before things go completely far off
 

Mike G

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John (All In)
"you could force her to parallel the runway gaining speed"
think 737 MAX.

If you want RTB training we have to discuss again because the last time you wanted me to train one PRA guy, he makes a video during training and you go on to sell, or give, it to your members. Sorry but no, that would be unfair on all those that have already paid for training.

For the GWS, the work with Abid will be all prototype work and I doubt if Abid will want guys milling around while we do that and I certainly don't. When it's up and running I'm sure Abid will report back here on the forum.

Mike
 

fara

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John (All In)
"you could force her to parallel the runway gaining speed"
think 737 MAX.

If you want RTB training we have to discuss again because the last time you wanted me to train one PRA guy, he makes a video during training and you go on to sell, or give, it to your members. Sorry but no, that would be unfair on all those that have already paid for training.

For the GWS, the work with Abid will be all prototype work and I doubt if Abid will want guys milling around while we do that and I certainly don't. When it's up and running I'm sure Abid will report back here on the forum.

Mike
Yeah we don’t want others while we do installation and testing of GWS the first time.

the idea is to determine its effectiveness and price and see if we make it a part of our platform as standard equipment.
 

Mike G

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I am putting together a presentation for my GWS (Gyro Warning System) and want to illustrate each of the accident scenarios that the GWS covers with a video of a crash. I have reasonable videos for most but does anyone have a decent video of a flapping (blade sailing) crash?

I have found this one:


but seem to remember that there was a discussion about whether it was actually flapping or not so I’m looking for another.

In my attempt to really understand flapping on take off I’d like to know if anyone knows any more about the accident in that video.

Where was it?

What gyro type was involved?

What was the direction of rotation of the rotor ?

and

what was the direction of rotation of the prop?

MikeG
 

Mike G

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Doug

Thanks for the feedback.

My interest in this accident comes from my continual development of the GWS system.

During a discussion with Jean Claude Debreyer, we tried to understand this accident and saw 3 potential causes that were important for the GWS.

  • The pilot simply didn’t pre rotate to a high enough Rrpm. A classic blade flap.
  • The pilot pre-rotated to the correct Rrpm and accelerated with the stick back but did not advance the stick when the nose wheel left the ground. This caused an even higher disc AoA and flapped the rotor to the left.
  • As 2 but the pilot then pushed rapidly on the stick forward, unloaded the rotor and (because the engine was probably at full power) torque rolled to the left. This assumes that the prop rotates clockwise, hence my request for people who actually knew this machine/accident.
In case 1 the GWS would have warned him but in cases 2 and 3 I’m not sure what would happen. I’ve started try to test case 2 but it’s getting a bit hairy.

So I ask again does anyone know anything about this accident or can they identify the gyro type and even the engine?

Mike G
 

Mike G

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During some recent testing I had a reasonably strong cross wind so decided to see if the GWS would detect a X wind take off with the stick fully back and into wind. I know of one accident in France where this was the cause and I think it was discussed here some time ago.


The first TO in this his video shows a X wind take off with the correct pre rotation Rrpm and the stick back and centered. The 2nd TO is again with correct pre rotation and stick fully back but with the stick to the left into the X wind.

You can see and hear that the first TO goes without any problems or warning but in the second TO Jean Claude Debreyer’s prediction algorithm detects within about a second that the airspeed is rising faster than the rotor speed and gives a warning predicting a potential flapping even before the flapping angle indicator starts to indicate a worrying angle. You can see that I centered the stick and reduced power allowing the rotor to catch up and the TO continued safely.

I post this to show that the GWS development is continuing and to perhaps help ex FW pilots to abandon the practice of into wind stick on TO.

Mike G
 
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fara

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During some recent testing I had a reasonably strong cross wind so decided to see if the GWS would detect a X wind take off with the stick fully back and into wind. I know of one accident in France where this was the cause and I think it was discussed here some time ago.


The first TO in this his video shows a X wind take off with the correct pre rotation Rrpm and the stick back and centered. The 2nd TO is again with correct pre rotation and stick fully back but with the stick to the left into the X wind.

You can see and hear that the first TO goes without any problems or warning but in the second TO Jean Claude Debreyer’s prediction algorithm detects within about a second that the airspeed is rising faster than the rotor speed and gives a warning predicting a potential flapping even before the flapping angle indicator starts to indicate a worrying angle. You can see that I centered the stick and reduced power allowing the rotor to catch up and the TO continued safely.

I post this to show that the GWS development is continuing and to perhaps help ex FW pilots to abandon the practice of into wind stick on TO.

Mike G

Interesting. That was a very quick warning.
I am assuming this takeoff is basically a version of cross control on initial takeoff run where you are accelerating forward on the ground like you would normally with all 3 wheels on the ground.
I am curious as to what this would indicate if you were already balanced on mains meaning the rotor already was starting to load up.
I actually do takeoffs where I will use slight into the wind stick after my front wheel has left the ground but the mains are light but not quite completely clean off the ground. It seems to me that a slight cross control there helps me not to drift off the center line in crosswinds. It seems to work fine but am I putting myself in a flapping risk. It doesn't seem to me that I am because I am watching the rotor RPM gauge and making sure my trend on it is positive; otherwise, I pull the power and bring the stick smoothly back and abort the takeoff. Yes I know this requires a rotor RPM gauge and I know the old schoolers will tell me you have to feel the rotor and rotor RPM gauge is not needed. Ok but I'll stick with my rotor RPM gauge if I have one.
 

Vance

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During some recent testing I had a reasonably strong cross wind so decided to see if the GWS would detect a X wind take off with the stick fully back and into wind. I know of one accident in France where this was the cause and I think it was discussed here some time ago.


The first TO in this his video shows a X wind take off with the correct pre rotation Rrpm and the stick back and centered. The 2nd TO is again with correct pre rotation and stick fully back but with the stick to the left into the X wind.

You can see and hear that the first TO goes without any problems or warning but in the second TO Jean Claude Debreyer’s prediction algorithm detects within about a second that the airspeed is rising faster than the rotor speed and gives a warning predicting a potential flapping even before the flapping angle indicator starts to indicate a worrying angle. You can see that I centered the stick and reduced power allowing the rotor to catch up and the TO continued safely.

I post this to show that the GWS development is continuing and to perhaps help ex FW pilots to abandon the practice of into wind stick on TO.

Mike G
That is simply brilliant MikeG and a wonderfully clear demonstration of the value of the device.

I have been criticized more than once for advocating beginning the takeoff roll with the cyclic centered in a strong cross wind takeoff (10kts+ cross wind component) and using less throttle for a longer takeoff roll.

I would love to have that device to aid in instructing in my aircraft although I am not sure where I could put the display.

Just the audio would be a wonderful training aid because I could demonstrate the less desirable procedure with less risk.

It appears it is counterintuitive for some gyroplane pilots.

Thank you for all your effort and creativity.
 

Burrengyro

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Hi Mike,
Really interesting video. In the first takeoff, the rotor rpm did not seem to drop from the initial pre-rotation rpm of 200. In the second takeoff, if I understand correctly, you took off with the stick to some extent into the crosswind. By how much? The rotor rpm did look like it dropped to about 180 rrpm when the GWS sounded. You seemed to change your stick attitude to correct the danger of flapping. Could I ask which direction was the crosswind coming from? Would a port side crosswind be more useful than a starboard side crosswind for rotors which turn normally anticlockwise if one brings the stick back fully straight for the normal takeoff, but slightly into the crosswind in such a crosswind takeoff?

I have to admit I only occassionally watch the rrpm gauge on takeoff as I prefer eyes out and down the runway. The GWS looks to be a really useful warning system and audio warning is method is excellent. Best regards, John H.
 

Mike G

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Abid

You must remember that none of my flying over the last year or so has been according to the POH because I’m constantly teasing the GWS to see where its limits are and trying to develop the algorithms to reduce the number of unnecessary alarms.

The TOs in the video show:

Because I only have a 100 HP 912 I keep the gyro light and go to WOT the moment I release the pre-rotator and bring the stick back all in one movement. This give me the max acceleration I can get to push the GWS. Typically, the nose wheel leaves the ground after about 6 seconds and the mains leave the ground a second or two later. This is what you can see in the videos. I simply don’t have the time to “balance on the mains”.

So I’d guess that if you are “balancing on the mains” when you move the stick into wind, you are probably not at WOT but doing a correct TO with a gradual/steady/partial opening of the throttle, otherwise with your 914/915 power I imagine that your acceleration would be much higher than mine. If you’re leaning the stick into wind after your nose wheel is off the ground, I imagine that you’ve already moved the stick forwards and hence the flapping risk is greatly reduced. So, I’d say your technique isn’t problematic, there is much more flapping risk while the stick is fully back.

The only comment I’d make is that you’re creating different TO procedures for the cross wind and into wind and since those pilots that are flapping on take-off have already lost the plot with the standard into wind TO procedure, asking them to remember and apply a different one (that IMHO has little to no real advantage except perhaps to maintain alignment with the runway) simply increases the probability that they’ll f..k it up.

It’s important to understand the philosophy behind the GWS alarms. If you fly by the POH you should never hear the GWS except as you round out on touchdown and go “behind the curve”, like the stall warning on a FW.

There are two levels of alarm:

Amber & Red.

Amber is a “heads up” alarm that is telling you that this is not a “normal POH” situation but you still have some margin to react.

If you are taken by surprise by the amber alarm, it suggests that you’ve unwittingly allowed yourself to operate outside the POH limits. If this is during a TO the best action is to abort the TO and try to understand what you did.

If you are not taken by surprise, it suggests that you knew that you were operating on the limit and the amber alarm is simply telling you what you expected and that you should carry out the appropriate corrective action and prepare yourself for a red alarm. In the video I centred the stick and reduced power and the problem went away, there was no red alarm and I continued the TO.

If you then get a red alarm this would be telling you that it’s time to get your head out of your ass, you’re about 2-3 seconds from disaster and you really must react correctly.

I’d hoped to be able to get you up to speed on all this by visiting you earlier but covid has got in the way. We’re looking at sending you an earlier prototype for installation and perhaps some setup to get you up to speed while we’re waiting for me to be able to come over. It’ll be a pain to do over the internet but if we don’t, we’ll never move forwards.

Vance

If I had the choice, you would be my first test instructor because you are well respected and vocal on social media. You also appear to enjoy reporting on what you do and could be relied upon to feedback comments, criticisms and ideas. Unfortunately, this is unlikely to happen because the installation of the GWS requires quite a bit of calibration for the particular model, hence our decision to work only with manufacturers. Once we’ve trained them and setup the GWS for each of their models we’ve finished. To do that with your Predator would mean me flying half way around the world to carry out a unique installation. If you were here in France (or me in California) you’d already be operating one of our few prototypes.

By the way there is no display, the flapping angle display you see on the video is only for testing and initial setup. The installation only has a warning light, a combined volume controller/mute button and a connection to your intercom. As an instructor you could also have a push button to set off different alarms when you wanted.

A French instructor upon seeing the GWS admitted to me that he’d never demonstrated flapping on take-off to his pupils because he didn’t know where the limits were. He said it would be great for him, he would be able to demonstrate a bad take-off because he could approach the limits with confidence knowing that the GWS would effectively tell him when to reduce power.

John

The standard ASI and rotor tacho are notoriously inaccurate.

From the GWS “black box” recording:

In the first TO with stick fully back and centred, the Rrpm fell from 207 to 197 rpm before it started to rise again. At the same time the airspeed rose from 0 to 50 kph in 3 seconds.

The second TO with the stick fully back and into wind (from the left), the Rrpm fell from 204 to 192 (so you could say that the second TO had a slight Rrpm disadvantage). During that period the airspeed went from 0 to 50 in 2 seconds and that is the key. The GWS recognised that the airspeed was climbing too fast and gave an amber warning. I can’t see from the video but I’m pretty sure that muscle memory made me centre the stick as soon as the alarm went off. Now that I’ve been able to download the data and see how much margin I had I intend to do this test again and hold the stick into wind to see if I get to a red alarm state.

What this shows is how little time we have for the GWS to decide if there should be an alarm or not, all this has to happen within the first few seconds of gyro acceleration.

For your question about most useful X wind direction, I don’t know the answer, I’d say that it makes no difference but await the comments oof more knowledgeable members.

Mike G
 

Jean Claude

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John,
There is a slight asymmetry between the left crosswind and the right crosswind:
The non-uniformity of the induced speed produces a transversal flapping angle and, in case of divergence, the impacts against the flapping stop will not occur exactly at the back point, (relative to the relative wind) but after an little additional rotation.
Sans titre.png
Unfortunately this does not change the disaster caused by these impacts.
 

Burrengyro

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John,
There is a slight asymmetry between the left crosswind and the right crosswind:
The non-uniformity of the induced speed produces a transversal flapping angle and, in case of divergence, the impacts against the flapping stop will not occur exactly at the back point, (relative to the relative wind) but after an little additional rotation.
View attachment 1153715
Unfortunately this does not change the disaster caused by these impacts.
Hi Jean Claude,
Thank you! For my ELA07S, the max crosswind limitation is 16 kt. I can land without any problems across our grass runway for crosswinds of 16 kt.

Which is better: a takeoff with crosswind directly from the left; or a takeoff with a crosswind directly from the right for safety and to avoid flapping? We have only one runway and crosswinds happen regularly.

There may not be much of a difference between these two options if you can turn into wind when best climb airspeed is reached. However, if you are required to maintain runway direction for obstacle avoidance, any technique which gives an advantage is worth learning. Any pilot can make a mistake and Mike's GWS could help prevent disaster once the pilot takes the correct action. Many thanks to you and Mike and to the forum members who contribute to this good work. John H.
 

fara

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Hi Jean Claude,
Thank you! For my ELA07S, the max crosswind limitation is 16 kt. I can land without any problems across our grass runway for crosswinds of 16 kt.

Which is better: a takeoff with crosswind directly from the left; or a takeoff with a crosswind directly from the right for safety and to avoid flapping? We have only one runway and crosswinds happen regularly.

There may not be much of a difference between these two options if you can turn into wind when best climb airspeed is reached. However, if you are required to maintain runway direction for obstacle avoidance, any technique which gives an advantage is worth learning. Any pilot can make a mistake and Mike's GWS could help prevent disaster once the pilot takes the correct action. Many thanks to you and Mike and to the forum members who contribute to this good work. John H.

I don't know from the perspective of flapping but to me since the torque and p-factor on takeoff (breaking ground) usually require left stick and right rudder (Rotax 91x series engines, Yamaha and 582 etc. will be opposite) crosswind from the left is always preferable.
 
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All_In

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Way to make it happen, Mike!
Thank you, if there is anything I can do to help, let me know.
 

Burrengyro

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Hi Abid,
The presence of ruts and rough ground requires us to get out of the grass as quickly as possible with the attendant risks of jolting the rotor or overspeeding at the initial takeoff phase. Wet weather affects our grass runway surface a lot during the winter. We follow your method using WOT as soon as possible. Thanks for your comment on the left side crosswind preference! John H.
 

All_In

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After a rain the pyrotechnic club would leave ruts like that next to the runway where many taxi back, off runway, at PRA's convention fireworks show.
In the contract, we required them to resort it.
Had them rent a huge roller machine and they flatten the grass back to smother that it was originally. That is the only real solution once rutted each new rut makes it worse over time.
 

Mike G

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Here's a bit of video showing the mute button working. The amber alarm "behind the curve" is behind the DRAG curve and the red alarm "Max power descending" is behind the POWER curve.
You can see that by pressing the mute button the warning stops for 20 seconds, this time delay is adjustable.
You can also see that the alarm light (just to the right of the mute/volume controller) is flashing all the time
The owner can record what ever message he wants.
Mike G
 
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