HeliTrak Collective Pull-Down for R-22
Thread Starter
HeliTrak Collective Pull-Down for R-22
This company is local to me, and the missus is looking to perhaps apply as a software engineer - I'd never heard of them:
http://www.helitrak.com
They appear to have a single product only recently introduced and not yet ready for prime time, which is aimed rather squarely at the R-22 (initially). This device is an automatic reaction to the low rotor RPM warning in the Robbie, literally yanking the collective down to re-establish rotor RPM.
It's a brilliantly simple package from all appearances and seems to address a common low-inertia problem. What I don't know yet is whether it offers a graduated response (lowering the collective only enough to satisfy RPM requirements, or if it simply slams the collective to the stops) nor how quickly it releases the collective back to the pilot's control.
It's a bit more than a stick shaker, obviously. On first blush it seems like a great idea... but depending on the operating parameters it also sounds like a potential fright.
I'm curious as to the opinions of the group.
Disclaimer: I have no ties to nor interest in the company in question and am only interested in the device as it pertains to helo safety. Unless the missus ends up working there at some point, anyway...
http://www.helitrak.com
They appear to have a single product only recently introduced and not yet ready for prime time, which is aimed rather squarely at the R-22 (initially). This device is an automatic reaction to the low rotor RPM warning in the Robbie, literally yanking the collective down to re-establish rotor RPM.
It's a brilliantly simple package from all appearances and seems to address a common low-inertia problem. What I don't know yet is whether it offers a graduated response (lowering the collective only enough to satisfy RPM requirements, or if it simply slams the collective to the stops) nor how quickly it releases the collective back to the pilot's control.
It's a bit more than a stick shaker, obviously. On first blush it seems like a great idea... but depending on the operating parameters it also sounds like a potential fright.
I'm curious as to the opinions of the group.
Disclaimer: I have no ties to nor interest in the company in question and am only interested in the device as it pertains to helo safety. Unless the missus ends up working there at some point, anyway...
Last edited by Hedge36; 5th May 2015 at 15:52. Reason: Clarified URL
Sometimes you don't want the collective to be pulled down, e.g. in an engine failure in the hover or hover taxi.
Also, and critically I think with the R22, if the horn comes on due to overpitching, obviously a more gradual reduction in rotor RPM than a flat out engine failure, the throttle must be rolled on at the same time as the collective is lowered, otherwise the compensator will close the throttle and worsen the situation.
At first glance my feeling is the benefits of it might not outweigh the drawbacks.
Also, and critically I think with the R22, if the horn comes on due to overpitching, obviously a more gradual reduction in rotor RPM than a flat out engine failure, the throttle must be rolled on at the same time as the collective is lowered, otherwise the compensator will close the throttle and worsen the situation.
At first glance my feeling is the benefits of it might not outweigh the drawbacks.
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"I thought the pilot was supposed to do that"
Yes he was/is but he was also meant to keep the needles in the green but then they developed a governor. Anything which helps safety especially on the R22 shouldn't be mocked but as Arm Out stated it's often not as simple as just dropping the lever. I doubt if that's all this product does that it will make it to market.
Yes he was/is but he was also meant to keep the needles in the green but then they developed a governor. Anything which helps safety especially on the R22 shouldn't be mocked but as Arm Out stated it's often not as simple as just dropping the lever. I doubt if that's all this product does that it will make it to market.
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I wonder what it does in the marginal situation of the low RRPM warning just triggering intermittently which is not an uncommon event for a fully loaded robbie and its narrow power bandwidth.
One could save themselves a few dollars and learn to simply lead all manoeuvres with the RRPM, even a more powerful engine would help if the rubber bands can handle it, however because the robbie has become a popular helicopter I'm sure this device will save the lives of those that are more about show than substance.
One could save themselves a few dollars and learn to simply lead all manoeuvres with the RRPM, even a more powerful engine would help if the rubber bands can handle it, however because the robbie has become a popular helicopter I'm sure this device will save the lives of those that are more about show than substance.
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Given that this could operate in any attitude / during any manoeuvre, is there not also a risk that this could create a 'negative g' situation for the unfortunate pilot?
What about trying to stretch an auto; horn sounds and the lever drops automatically?
Started with "not sure I want one of these" and got to "pretty sure I don't want one of these" in very little time at all.
What about trying to stretch an auto; horn sounds and the lever drops automatically?
Started with "not sure I want one of these" and got to "pretty sure I don't want one of these" in very little time at all.
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Hmmm...
The trouble I see with the Robinson governor is its kind of reactive, rather than pro-active.
I would have thought that a better option would be to change the software (if its not simply analogue) in the R22 governor to implement a proper PID (Proportional, Integral, Deferential) routine, when the rate of RRPM change and positional change of the collective would determine the increased (or decreased) rate of throttle opening, you could monitor the RRPM drop and direction and acceleration of collective travel and pre-empt the throttle to full before the horn sounded... Its a common technique in software, use it here on stuff I make (gritters and snow ploughs) Plus its kind of what I do in the 47.
Mind you if its an analogue governor, which having flown a 44 I suspect it is then its not so simple to do.
Cheers all
Kev.
The trouble I see with the Robinson governor is its kind of reactive, rather than pro-active.
I would have thought that a better option would be to change the software (if its not simply analogue) in the R22 governor to implement a proper PID (Proportional, Integral, Deferential) routine, when the rate of RRPM change and positional change of the collective would determine the increased (or decreased) rate of throttle opening, you could monitor the RRPM drop and direction and acceleration of collective travel and pre-empt the throttle to full before the horn sounded... Its a common technique in software, use it here on stuff I make (gritters and snow ploughs) Plus its kind of what I do in the 47.
Mind you if its an analogue governor, which having flown a 44 I suspect it is then its not so simple to do.
Cheers all
Kev.
Thread Starter
Each of your reactions touches on issues which cropped up in my own mind as I eyeballed the product.
Also, I wonder if this isn't a cure in search of a problem - how many low-RPM accidents have there actually been in Robbies, anyway?
I told the missus that if she really wanted to develop a money-maker and life-saver, she needed to develop a simple bolt-on control assist which reloaded the rotor whenever a Robbie went zero-g. Hell, you could drive it with iPhone accelerometers, those things are in everybody's pockets already.
Also, I wonder if this isn't a cure in search of a problem - how many low-RPM accidents have there actually been in Robbies, anyway?
I told the missus that if she really wanted to develop a money-maker and life-saver, she needed to develop a simple bolt-on control assist which reloaded the rotor whenever a Robbie went zero-g. Hell, you could drive it with iPhone accelerometers, those things are in everybody's pockets already.
There's a sobering clip of a 44 (I think) falling out of the sky with stalled blades somewhere in England where they might have been helped by a collective pull-down system, but again I reckon the benefits of this one would be outweighed by the negatives.
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Notice the web site shows features and benefits, but no mention of cons or price.
A lot of bashing here on something no one seems to know much about. I don't have tons of time in the 22 but fly them occasionally for maintenance or ferry. Recently had to fly a beta 2 from the bottom of the south island in New Zealand up to Auckland. Around 9 hrs cross country - I would have been glad to have something like this installed. I like to think I have quick reflexes but everyone knows how quickly the RRPM decays in a 22. Midway through a long day of boring cross country flying I am sure that having something help get the collective down quickly in an emergency would be a welcome addition and could probably save a few lives.
I have heard that it takes about 0.9 seconds for the RRPM to be unrecoverable after a power failure at high power settings in the 22, and about 1.0 seconds for the average human to react. that doesn't leave much of a margin to get the lever down....
I imagine that this would be completely pilot "over ridable" in a similar way to the governor is. I would be interested in seeing one in action for sure.
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That point, raised a few posts up, would be of interest to anyone interested in this proposed "fix" to a primary flight control.
Question number two: how does one account for and filter out "false positive" signals to command this gadget to pull down when it isn't really needed? Threshold RPM looks to be 97% Nr from the technical description.
For those interested, the patent description is available http://www.google.com/patents/US8651425:
