Flapping warning device

loftus

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I imagine this device would be pretty easy to calibrate for nominal RRPM simply by flying the gyro in a stable configuration or according to specs. I think it could be a great tool. Does not really tell you anything that you can't see on the RRPM gauge but if placed in a prominent position say on the upper panel could be very helpful, sort of like an AOA indicator in a FW. Alternatively a device like this could be incorporated into a digital RRPM meter to provide all the info in one. Pretty straight forward, green light is good, red light, check yourself. Could become a new standard in RRPM gauges. I'd absolutely put one in my next gyro.
 
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WaspAir

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I have a general comment and some questions about functions (2) through (4) in your first post.

The comment is that one needs to be careful about providing too many distinct warnings, or having too much confidence in how the pilot will react to them. In an extreme case, one of the recent 737-MAX reports suggested that crew reaction was not what Boeing or FAA expected, and perhaps that is worth considering here. Granted, one is unlikely to get multiple warnings at once to confuse the issue as can happen in a complicated airliner cockpit, but one must still process which warning it is and what should be done about it. Maybe there is virtue in keeping it simple and not providing too many artificial cues for too many situations in the same device (physical cues being already provided by the aircraft and instruments), for easier and more reliable response by the pilot. I think there may be merit in solving one big problem well without trying to solve them all, from a human factors standpoint.

Now the questions:

As to (2), "behind the power curve" flying, one will be in the region of reversed command whenever slower than minimum power required speed, including slow flight at altitude, vertical sinks, and so forth. It's really only a problem when very close to the ground with the intention to climb, as in the FAA PTS tasks for "liftoff at low airspeed and high angle of attack" (the pilot-candidate is expected to detect the development of that condition and take prompt corrective action). I would find a warning under any other flight regime to be extremely annoying, especially if it seemed to come on too often. Áre you planning any sort of above-ground altitude input for this? Were you planning to address high sink rate conditions at altitude with this as well?

For (3), is this just an aural / warning light addition to the normal function of the lower arc of a g-meter?

As to (4), I question how one would get into a situation with simultaneous high mu and "low" rpm. At retreating blade stall, the rotor rpm will indeed be low relative to the forward speed, but not low in any other sense and should be expected to be noticeably above normal cruise rpm (assuming positive g-load; otherwise we're in one of the other situations). I've never gone all the way to retreating blade stall in a teetering rotor gyroplane (if I interpreted his comments properly, I believe Mr. Beaty has suggested elsewhere that this would amount to a benign stick full-forward situation before any catastrophe ensuses) but in the A&S18A one gets increasingly uncomfortable vibration that provides ample warning, and no sudden departure from controlled flight (helicopters can produce a pitch-up that is a speed-reducing and thus a self-correcting tendency). In short, I don't really perceive a problem needing a cure here. What is believed to have gone wrong in the accident you mentioned?
 

Jazzenjohn

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It is fairly easy to connect devices through bluetooth if needed.
Is the concern the progression of flapping is to great for an inexperienced pilot to be able to handle? That seems to imply an active correction device doesn't it?
 

EI-GYRO

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Ah, re-reading your original post I see you were describing your work in progress rather than seeking opinions/suggestions. Apologies for the misunderstanding.
 

loftus

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Mike, sorry I was referring to the sparxfly device that Alan was referring to. Seems to me that a device that simply notifies in a graphic way (red or green) whether the blade is decelerating or stable or accelerating may be a more practical device and give earlier warning of a problem than a bump device.
 

gyrojake

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Hey Mike, when I designed my analog wireless rotor tach, I put yellow, green, and red indicators on the graph.

100_0004.JPG
 

fara

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"Similarly, having a prerotator system which does not allow the rotor disk to be tilted back while prerotating is inefficient in operation, and
results in a 'bunched' sequence of actions while transitioning from prerotation to takeoff roll....."

Spot on. As far as I'm aware this is not happening on Magnis.
And besides training why would it not happen on Magnis. As far as I can tell from flying a few hours in M16 and checking out M24 this weekend, their system has no centrifugal teeter stops like Commander Wallace gyroplanes or any other device that would stop it. The system in Magni in concept is almost the same as AR-1. Mechanically actuated and can be kept engaged while stick is pulled back. It relies on the pilot to use it correctly.

Am I missing something? I do not see or know of anything in Magni design that stops a pilot from pulling the stick back at 100 RRPM all the way and at the same time accelerate to say 25 mph and that will cause a flap in short order
 

Brian P

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And besides training why would it not happen on Magnis. As far as I can tell from flying a few hours in M16 and checking out M24 this weekend, their system has no centrifugal teeter stops like Commander Wallace gyroplanes or any other device that would stop it. The system in Magni in concept is almost the same as AR-1. Mechanically actuated and can be kept engaged while stick is pulled back. It relies on the pilot to use it correctly.

Am I missing something? I do not see or know of anything in Magni design that stops a pilot from pulling the stick back at 100 RRPM all the way and at the same time accelerate to say 25 mph and that will cause a flap in short order
I doubt that centrifugal stops would stop it. I think they are only for keeping the blades from moving during taxi....and disengage at a fairly low rpm.

I tended to agree with Fergus that the rushed procedure of disengage pre spin.. stick back and full throttle could lead to mistakes but if your machines are spun up stick back and it is still happening maybe not.
 

fara

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What does your POH say about stick position during pre rotation I can't remember from when I flew the AR1 with Greg?
I agree with Brian I don't see how those centrifugal flap stops would help during pre rotation but useful during taxiing.
Mike
Currently the POH states that pre-rotation should be started in forward position and at 140 to 160, the cyclic can be brought back and brakes released to start a slow movement forward.

I am going to change it to dis-engage pre-rotator at 180 to 220 RRPM in forward position and bring the stick back and then increase power to cruise power till nose starts to lift and rotor RPM is increasing, forward pressure on cyclic to maintain attitude so nose wheel is just off the ground a little and then go to full power, accelerating to safe climb speed and allowing the gyroplane to leave ground effect and climbing up. Seems simpler and reduces ground roll. I have been using it personally, testing it against the other procedure and see longer ground roll with other methods. One could also keep pre-rotator engaged while stick is pulled back for shortening the ground roll further if really needed but safe climb speed still has to be reached in ground effect before climb out begins

The last incident, the pilot moved the stick back at 100 RRPM and tried to accelerate faster because he was worried about a plane given clearance to land by the tower behind him that was on final. So he flapped the rotor by outrunning the rotor with his faster acceleration at too low Rotor RPM
 
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Brent Drake

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I don't think a sensor is needed. I believe that more training is needed. It's not rocket science. Just pay attention to details.
 

dinoa

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Putting max torque through prerotor u-joints at aft stick probably shortens their useful life
 

EI-GYRO

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Currently the POH states that pre-rotation should be started in forward position and at 140 to 160, the cyclic can be brought back and brakes released to start a slow movement forward.

I am going to change it to dis-engage pre-rotator at 180 to 220 RRPM
Please don't change it. Your current POH is much better. If you change it you will put yourself in the same position as the others.
And your 100 rpm guy didn't follow your current POH, either.
Some things you can't prevent.
 

Vance

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I don't know what ATC is like in Florida.

In California several towers have specifically requested that I not stop on the runway to spool up.

In AutoGyro products I always follow the procedure in the POH and stop in the middle of the runway to pre-rotate.

With a primary student it may take a while and I always tell the tower of the expected delay so they can schedule arrivals.

One of the things I like about the AR is being able to pre-rotate on the fly.
 

fara

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Putting max torque through prerotor u-joints at aft stick probably shortens their useful life
That's correct. That is why you should use it when you really need to and not for normal operations. The cost of the U-joint is $65 from us for our customers and changing it out is simply one bolt out and in. Its not that bad. Its only the top U-joint that gets an angle.
 
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fara

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I don't know what ATC is like in Florida.

In California several towers have specifically requested that I not stop on the runway to spool up.

In AutoGyro products I always follow the procedure in the POH and stop in the middle of the runway to pre-rotate.

With a primary student it may take a while and I always tell the tower of the expected delay so they can schedule arrivals.

One of the things I like about the AR is being able to pre-rotate on the fly.
I go line up on the runway and then pre-rotate. It can be done the other way also but I always take the runway announcing delayed departure for pre-rotation. Its exactly 40 seconds from zero to 180 RRPM. Not sure how much of those 40 seconds will I save doing it the other way. May be 20 or 25 seconds at most. I'll have to check. So far I have had no one ask me not to line up and pre-rotate but I would be courteous on a busy tower. I won't get rushed though. I would rather deny clearance for immediate departure and wait than flap the rotors.
 
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fara

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Please don't change it. Your current POH is much better. If you change it you will put yourself in the same position as the others.
And your 100 rpm guy didn't follow your current POH, either.
Some things you can't prevent.
But may the others had the same kind of things happen too and just put the rotor RPM so high to try and reduce the chance of a flap? That didn't help either I think. You are right you can't do much about people making bad judgments
 

Housedr

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Mike- I follow your logic quite well. Perfectly understood that at any time , distractions can cause a deviation in procedure and a warning that you have deviated might well wake you up before it’s too late.
Airliners use a stall warning just for that purpose.
Most times you don’t need it but when work load goes up- it might save your bacon.
In my following exampleA I see how this would work well.
Short field grass takeoff. 60 ft object nill wind.
Pilot in command calculates a go no go sequence and sets his parameters for wheels up.
He starts his prerotation and moves along- approaching quickly his wheels up mark presses on just a bit too much to make the mark- alarm goes off.
If he had more runway- he could easily just back off a bit- Stabilize and press on.
In our 60 DT object short field scenario he could just abort and turn around and try again.
 

PW_Plack

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You could have a mechanical warning device where, if the blades were flapping too much they would hit stops, sending a pulsing signal through the stick that would get stronger and stronger if the problem wasn't immediately corrected.
Teeter stops for the teeter stops?

I guess you could position little spring-loaded plungers poking through holes in the teeter stops, with an electronic sensor to detect plunger movement, and use it to fire a warning light if things got too close.

We could program a PIC to compare airspeed and rotor RPM through a lookup table, and trigger a warning if the ratio between the two values got out of whack.
 
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