Gyro Warning System

[Mike G]

Here is a video I managed to take today that gives an idea of what my Gyro Warning System does. I had an air compressor failure that meant I didn’t have trim, rotor brake or pre rotator so had to use the manual system. It was bl..dy cold and the ceiling was pretty low limiting what I could do.

The first TO is with 150 Rrpm, pre rotator off and WOT. You can hear the warnings « Flapping Risk » followed by « Flapping, Flapping, Flapping »

The second TO is 200 Rrpm but leaving the stick forwards, you can hear the warnings « Flapping Risk » followed by « Flapping, Flapping, Flapping ».

The third TO is done simulating a Hot, Heavy and High TO, it was none of those so I simply took off with less power. You can hear the alarm « Behind the curve ».

You can then see a downwind leg where I pull up on the stick and then push. This gives the warning « low G bunting risk ». If I continued to push it would give the alarm « Bunting Bunting Bunting ». This alarm still needs some work.

You can then see that I make too tight a turn onto base and finals and loose airspeed. The alarm « Behind the curve » sounds followed by « Max power descending » as the speed falls even further.

During the landing there is the inevitable "behind the curve" just before touch down.

Mike G

 

[Vance]

I have a much lower fear threshold than you do Mike G.

That is a very nice demonstration of your device.

I applaud you innovation and tenacity.

What does the number on the device represent?

 

[Abid]

Hi Mike:
Hopefully after this pandemic is under control better you can come over so we can install and develop something for AR-1 with better choice words thrown in. A device like this with proper training incorporated to do the right thing immediately as warning comes on would be a good attack on the problem. Training with usage of this device is a must. The last resort after low G event is pulling a chute if you have 500 feet altitude or more. The chances of full deployment then are high. The additional weight and cost penalty is there but its better than the alternative. I do not subscribe to the idea that once unloaded having differential tail will restart your rotors or save you from the obvious that's coming next in one form or another, rolled or straight

 

[Resasi]

Looks very impressive.

Congratulations on what would seem a big step up in a safety feature.

The only one that will be a distraction is the ‘inevitable’ one on landing.

 

[Abid]

I have a much lower fear threshold than you do Mike G.

That is a very nice demonstration of your device.

I applaud you innovation and tenacity.

What does the number on the device represent?

That number on the device/phone app got to be the measurement of the flapping angle. Obviously that is just for Mike's in-house development I would think. The device is invisible to the user completely. Just plugged into the intercom for warning

 

[JETLAG03]

The only constructive negative I could find is the voice (probably yours) is too soft and without a sense of urgency and as mentioned previously the warning on landing.

I found your video very informative and instructive and look forward to your market ready product.

thank you

phil

 

[XXavier]

That number on the device/phone app got to be the measurement of the flapping angle. Obviously that is just for Mike's in-house development I would think. The device is invisible to the user completely. Just plugged into the intercom for warning

It probably needs some sort of sensor in order to measure the maximum flapping angle at a given moment...
I think it's a very useful invention, and will probably buy one as soon as it becomes available...

I may be wrong, but I think that the angle displayed is the instantaneous flapping angle, measured at intervals of a small fraction of a second. The system is probably looking for the maximum flapping angle of all those measured within a long enough time frame, at least, that for half a turn of the rotor. Apart from the warnings, that are the important thing here, it would be interesting to have an instrument displaying that maximum flapping angle...

 

[Smack]

Mike, does your measurement only look at the flapping angle as measured at the relatively rigid hub bar? It would seem that you might need to measure the RATE of change in that angle as a higher rate would see the more flexible blades making a greater 'angle' (tips flexing lower than the hub bar angle implies).
Lower RRPM (less centripetal force) would also factor into blade flexibility, would it not?
As different blades are more/less flexible than those from other manufactures, would you need to calibrate your device and how?
Good job on developing this warning device !

 

[Mike G]

This warning system has 2 levels of alarm. The first is a pre-alert that is warning the pilot that the prediction is that, based on the current rate of progression of different parameters, he is likely to get the second alarm. It’s really to prepare him mentally to be ready to carry out the appropriate corrective action if the second alarm is activated.

For the flapping warning alarm this graph

shows the first TO in the video. The flapping “angle” and “state” (these are the different alarms) are on the secondary Y axis. There are 2 pre alarms that give the same message; these are alarms 1 & 3. Number 3 alarm is a predictive alarm using a logic/algorithm by Jean Claude Debreyer. Number 1 alarm uses real-time data in case there is a sudden change in one parameter that would be missed by the predictive logic such as a sudden gust of wind increasing the airspeed nearly instantaneously and flapping the rotor.

The second alarm is the Number 2 alarm it uses real-time data and the rate of change of different parameters to tell the pilot that if he continues at the current rate of progress he is very likely to flap the rotors within about 2 seconds and it’s time to carry out the appropriate corrective action that, thanks to the pre alarm, he should be mentally prepared to do

You can see from the graph that the number 3 predictive alarm goes off first giving a “flapping risk” warning. This is followed by a number 1 alarm giving the same message, followed by a number 2 alarm “flapping, flapping, flapping”. This N°2 alarm starts at about 17.2 secs and you can see that the flapping angle is increasing at such a rate that it would hit the 8° flapping angle at about 19.5 secs. 8° is when my rotor hits the flapping stops.

You can also see that from releasing the pre rotator to 8° flapping angle is about 6.5 seconds, things happen very fast.

This graph shows the data that would be available for any post crash investigation (assuming the SD card wasn’t destroyed in the crash). If this ever gets to a production stage we’ll be looking at some sort of fire protection. The only data that would not be recorded would be the flapping angle that is recorded on a separate device for my testing. We are considering adding engine rpm and there is an external switch for something like the canopy lock.

You can see the flapping angle on my telephone on the instrument panel. Knowing the flapping angle is important for me because that is what allows me to approach flapping with some degree of confidence. In my opinion it would be of little or no value to most pilots because it happens so quickly that by the time you saw it, it would be too late. That is why we use Jean Claude’s predictive logic/algorithm.

The voice on this prototype GWS is that of Mark Burton. For the production model (if we ever get there) the owner/pilot can record whatever message he thinks will generate the appropriate corrective action in whatever language he needs. If he thinks his wife’s voice saying “shut the f..ing throttle” will do the trick that’s fine.

The “inevitable” “behind the curve” warning as you flare is no different to the stall warning on most aircraft. In fact I’ve found it a good indicator that I’m not landing too fast. If I start to flare and don’t get that message I know something’s wrong. Also the GWS includes a volume controller (you can’t turn it down below a certain level) and a push button to stop the message for a set time period (actually at 20 seconds but adjustable).

For training there is an instructor push button to allow him to simulate the different alarms.

At the moment our thinking is that this would only be sold to manufacturers because it requires some serious flight testing to establish the different parameters for each gyro/rotor combination. Each manufacturer would have to decide where he wanted to put the limits for his machine. For example the bunting alarm at the moment is set with my personal G limits but a manufacturer may decide that they are too risky or too conservative, that must be his call.

Once they have established their parameters and created an installation kit they could offer it as a retro fit for existing customers if they wanted to.

Mike G

 

[JETLAG03]

@Mike G quote "If he thinks his wife’s voice saying “shut the f..ing throttle” will do the trick that’s fine."

That made me laugh out loud

phil

 

[XXavier]

Mike, does your measurement only look at the flapping angle as measured at the relatively rigid hub bar? It would seem that you might need to measure the RATE of change in that angle as a higher rate would see the more flexible blades making a greater 'angle' (tips flexing lower than the hub bar angle implies).
Lower RRPM (less centripetal force) would also factor into blade flexibility, would it not?
As different blades are more/less flexible than those from other manufactures, would you need to calibrate your device and how?
Good job on developing this warning device !

I believe that the flapping he measures is the real flapping angle, i.e. the angle of the hub bar w. r. to the rotor head, that varies periodically to compensate for the difference of lift between the advancing and retreating blade... The blades themselves may also flap a little, due to their elasticity, but that's very little, I think...

 

[Mike G]

Here you can just see part of the GWS behind the panel.

Here you can see the flapping angle sensor and Bluetooth transmitter.
As I said before it's if little value to the average pilot, more a distraction.
Mike G

 

[Abid]

I believe that the flapping he measures is the real flapping angle, i.e. the angle of the hub bar w. r. to the rotor head, that varies periodically to compensate for the difference of lift between the advancing and retreating blade... The blades themselves may also flap a little, due to their elasticity, but that's very little, I think...

yes the elastic nature of blades would very difficult to account for. But since the purpose of a system like GWS is pre warning hopefully enough centrifugal force is present to be able to ignore the elastic nature for the pre warning to be useful.

 

[NJpilot]

Couldn't a flapping warning be done by calculating blade velocity using rrpm and airspeed?

 

[Abid]

Couldn't a flapping warning be done by calculating blade velocity using rrpm and airspeed?

I believe that is how its being done. The flapping angle measurement is just for development. There should not be a flapping angle measurement in the actual system

 

[Mike G]

NJpilot
Rrpm and IAS are two of the "parameters" I talk about above. However as I tried to explain if you rely only on those parameters you get the warning either very (even too) late or you end up with a lot of spurious early warnings.
"been there done that".

Regarding the blade flexibility, as Fara points out, this is only an issue at very low Rrpm and flapping at those rpms is usually controllable by the pilot.
"been there done that"
I have a video somewhere of my early trials getting the rotor to flap in a strong wind to see if the GWS picked it up. I ended up touching the prop with the rotor but it was controllable and only marked the paint on the rotor.

Guys please don't get carried away by my flapping angle measurement, it is a prototype that Smart Avionics made for me, it's awkward to use and has nothing to do with the GWS. It simply allows me to overlay the actual flapping angle onto the GWS data recorded graph (see poste#9) to see how close I was to making a fool out of myself. You can see from the video that the values change very rapidly and it's not easy to follow what's happening. Mark Burton has no intention of making it available.

Mike G

 

[Abid]

NJpilot
Rrpm and IAS are two of the "parameters" I talk about above. However as I tried to explain if you rely only on those parameters you get the warning either very (even too) late or you end up with a lot of spurious early warnings.
"been there done that".

Regarding the blade flexibility, as Fara points out, this is only an issue at very low Rrpm and flapping at those rpms is usually controllable by the pilot.
"been there done that"
I have a video somewhere of my early trials getting the rotor to flap in a strong wind to see if the GWS picked it up. I ended up touching the prop with the rotor but it was controllable and only marked the paint on the rotor.

Guys please don't get carried away by my flapping angle measurement, it is a prototype that Smart Avionics made for me, it's awkward to use and has nothing to do with the GWS. It simply allows me to overlay the actual flapping angle onto the GWS data recorded graph (see poste#9) to see how close I was to making a fool out of myself. You can see from the video that the values change very rapidly and it's not easy to follow what's happening. Mark Burton has no intention of making it available.

Mike G

Hi Mike
I actually may like the flapping angle measurement for myself just to experiment.

 

[XXavier]

Hi Mike
I actually may like the flapping angle measurement for myself just to experiment.

I may like it too...

 

[Gyro_Kai]

Very impressive, indeed.

Kai.

 

[Jean Claude]

The flapping angle measurement is just for development. There should not be a flapping angle measurement in the actual system

Yes, Fara
Mike needed to know the proximity to the flapping divergence during his tests thanks to these flapping measures in live, but it should required a good mental interpretation to know whether it is the aerodynamic flapping or the flapping due to the delay relatively to stick movements. So it cannot be used for the flight itself
He consciously took risks to observe these margins and we can thanks him