PSC
Well-Known Member
- Joined
- Oct 21, 2015
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Hey guys and gals, Ive been lurking for a little while with work and a little side project taking up the majority of my time. Id mentioned my side project in an earlier post (HERE), but didnt give specifics. Now that Ive finished building it and have done some flight testing, Id really like to hear your opinions/constructive feedback/ etc.
So a little background:
Early on in my PPL training (pre-solo) a pilot at my home airport died in what appears to be a classic base-to-final stall/spin accident. I didnt know him personally, but its the same sad story weve seen before 39 yo mid to high time pilot, father of two, president of a construction company, upstanding citizen, flying since he was 17, piloting a late model Cirrus.
Given I was a brand new student pilot and only had a conceptual idea of what exactly happened; I was pretty shaken by the event. My instructor took this as a teaching opportunity for me. What followed was hours and hours of stall training, spin avoidance, and a few spins. He showed me that stalls are a manageable event, even turning stalls. If I reacted with reasonable speed, we lost only maybe 100 feet, usually less. Then he demonstrated the importance of coordination, by purposely spinning the aircraft with a less than extreme amount of cross control. Im paraphrasing, but he said something along the lines of you keep that ball centered, nothing you cant handle will happen. This is the day my obsession with coordination began.
I mean obsession literally my next instructor would routinely get on to me for letting my eyes linger on the instrument panel too long while making my downwind to base and base to final turns. Youre a VFR pilot, keep your eyes outside glance at the instruments and then go right back outside Hed say. It always bothered me that I had a stall horn to warn me 10 +/- knots above a stall, but what I deemed to be equally critical information (the turn coordinator) was lost low on the instrument panel.
Later on in my training, I learned that being uncoordinated caused me to lose airspeed at a faster rate demonstrated by slipping the airplane. This also served as a demonstration of how an uncoordinated aircraft at level flight will loose airspeed much more rapidly than if it were coordinated. If I failed to keep the nose down and pitch for airspeed, I'd loose airspeed quickly and approach stall speed in no time.
Background on my project:
I did some further research into stall/spin accidents and as it turns out, the majority occurred in VFR conditions and most were in airframes that are popular trainers and seem to be pretty docile in a stall. The base to final turn, as we all know, was a major culprit a bad pattern, wind, or other conditions caused the pilot to become unintentionally become cross controlled (uncoordinated) and the disaster was set into motion. Since the aircraft is uncoordinated and not pitched down enough to maintain airspeed, airspeed would bleed off much faster than it normally would on a stabilized approach - so the stall could sneak up on you - and since you're uncoordinated the spin followed quickly behind
I think at the root of the stall/spin problem is a lack of situational awareness. I think most of us can agree on that. Properly trained pilots wouldnt unintentionally become uncoordinated while low and slow if they knew we were doing it (Slips are disregarded here, as theyre an intentional act to burn off a known excess of energy).
While there are plenty of options to help a pilot avoid a stall, from Angle of Attack indicators to the basic stall horn installed on most aircraft, there aren't many supplemental alert options available for avoiding the spin. As you know, purchase price and installation of an AoA indicator is very high. Still, I think theres a place for them in aviation. Certainly if youre frequently operating at low speed or are a back country pilot, its a wise investment. If youre a weekend warrior like me who uses their plane to play around the patch on weekends with a few cross country trips each year, Im not sure the investment is worthwhile. I feel since Ive already got an okay indicator of impending stall (the installed stall horn), and Im rarely flying into a situation where dropping the nose and pouring the power on isnt an option - Im much less worried about the stall. Im more worried about the spin that could accompany an uncoordinated stall a spin that may not be recoverable.
My solution:
I built a device that I think can increase situational awareness, specifically coordination awareness. It can do this by taking coordination information out of the instrument panel and placing it in the field of view of the pilot looking outside. It uses LEDs to mimic the motion of the old ball in fluid indicator and can be placed on the glare shield or adhered to the instrument panel so that the pilot can clearly see coordination information at all times. Why do I think this is important? A picture is worth a thousand words:
Here, I'm riding along with my wife and our instructor on a training flight. What's important to note is where her focus is - on the runway. The turn coordinator is circled in red, low in the instrument panel and for all practical purposes, out of view. She's on a stabilized approach, albeit maybe a slightly early turn to final - but if she was really working to get lined up because of wind, distracted by other traffic, or distracted by making sure she turned on the fuel pump on - that turn coordinator would be almost impossible to notice.
Solution: Move coordination information up and into the line of sight, making it practically impossible to ignore.
More technically, the device utilizes a sensitive accelerometer (like the one youd find in your smart phone) to detect coordination. Logic is powered by an ATMEGA 328p 8 bit micro controller, which powers 11 LEDs that illuminate progressively from green, to yellow, to red from 0 degrees to 10 degrees each side, the same way the old inclinometer installed in your turn coordinator becomes progressively out of center. Its powered by two off the shelf AA batteries, and they seem to last about 40 hours or so. As a portable electronic device, it can be moved from aircraft to aircraft and doesnt require any pesky paperwork. Ive also built in a calibration function, so that it compensate for being placed on an unlevel surface (like a glare shield) place it where you want it, center your ball, and click the calibrate button.
Heres a picture taken during an early test flight:
(Not pictured - snap on base. Also using old style LEDs, which were hard to see)
Status of the project:
Ive got a few built and Ive done some basic flight testing on the device and Im happy to report that it works as expected. Ive got some additional testing planned if it would quit storming every afternoon. Ive learned a few things from flight testing, most importantly that the LEDs I was using, while very bright, werent easily visible from the sides. I swapped those out for LEDs that have a more opaque lens thats dimmer, but easier to see from any angle.
Assembly is pretty tedious work since all the components are surface mounted. If I go into even the smallest production run Im going to have to have a manufacturer assemble them for me. See this picture with the old style LEDs:
Who I think could use it:
First and foremost, Im building this for myself and others like me who maybe take coordination a little too seriously.
Past that, I see this as a great training tool for instructors during stall training. Since it uses LEDs its not subject to the parallax of a regular ball indicator and is accurately viewed from any angle.
Request from the forum:
Id like some general feedback from you guys. If flight tests come out ok, Im planning on doing a Kickstarter to fund the first production run. I know that there are some other solutions out there you could buy a secondary ball indicator like these but even those have to be installed and then you get into a whole other issue being that theyre not certified. That, and theyre kind of expensive for what they are. I've even found some options for purpose built portable electronic inclinometers, but their design is similar to the standard style inclinometer, rather than a progressive scale, which I think is an important feature and they seem to lack a calibration function.
Im planning on an early sales price less than $200, driven mostly by the expense of having the circuit boards printed and assembled in relatively small quantities. If demand grows enough, I can likely drive that cost down a good bit by buying in bulk.
My intent isnt to make the next Stratus as much as it is the novelty of having other pilots use something I built and the additional safety factor it could deliver. Though I guess if people would pay $900 each for them and I could sell them like hot cakes, then my flying budget would be a lot better.
Thoughts?
So a little background:
Early on in my PPL training (pre-solo) a pilot at my home airport died in what appears to be a classic base-to-final stall/spin accident. I didnt know him personally, but its the same sad story weve seen before 39 yo mid to high time pilot, father of two, president of a construction company, upstanding citizen, flying since he was 17, piloting a late model Cirrus.
Given I was a brand new student pilot and only had a conceptual idea of what exactly happened; I was pretty shaken by the event. My instructor took this as a teaching opportunity for me. What followed was hours and hours of stall training, spin avoidance, and a few spins. He showed me that stalls are a manageable event, even turning stalls. If I reacted with reasonable speed, we lost only maybe 100 feet, usually less. Then he demonstrated the importance of coordination, by purposely spinning the aircraft with a less than extreme amount of cross control. Im paraphrasing, but he said something along the lines of you keep that ball centered, nothing you cant handle will happen. This is the day my obsession with coordination began.
I mean obsession literally my next instructor would routinely get on to me for letting my eyes linger on the instrument panel too long while making my downwind to base and base to final turns. Youre a VFR pilot, keep your eyes outside glance at the instruments and then go right back outside Hed say. It always bothered me that I had a stall horn to warn me 10 +/- knots above a stall, but what I deemed to be equally critical information (the turn coordinator) was lost low on the instrument panel.
Later on in my training, I learned that being uncoordinated caused me to lose airspeed at a faster rate demonstrated by slipping the airplane. This also served as a demonstration of how an uncoordinated aircraft at level flight will loose airspeed much more rapidly than if it were coordinated. If I failed to keep the nose down and pitch for airspeed, I'd loose airspeed quickly and approach stall speed in no time.
Background on my project:
I did some further research into stall/spin accidents and as it turns out, the majority occurred in VFR conditions and most were in airframes that are popular trainers and seem to be pretty docile in a stall. The base to final turn, as we all know, was a major culprit a bad pattern, wind, or other conditions caused the pilot to become unintentionally become cross controlled (uncoordinated) and the disaster was set into motion. Since the aircraft is uncoordinated and not pitched down enough to maintain airspeed, airspeed would bleed off much faster than it normally would on a stabilized approach - so the stall could sneak up on you - and since you're uncoordinated the spin followed quickly behind
I think at the root of the stall/spin problem is a lack of situational awareness. I think most of us can agree on that. Properly trained pilots wouldnt unintentionally become uncoordinated while low and slow if they knew we were doing it (Slips are disregarded here, as theyre an intentional act to burn off a known excess of energy).
While there are plenty of options to help a pilot avoid a stall, from Angle of Attack indicators to the basic stall horn installed on most aircraft, there aren't many supplemental alert options available for avoiding the spin. As you know, purchase price and installation of an AoA indicator is very high. Still, I think theres a place for them in aviation. Certainly if youre frequently operating at low speed or are a back country pilot, its a wise investment. If youre a weekend warrior like me who uses their plane to play around the patch on weekends with a few cross country trips each year, Im not sure the investment is worthwhile. I feel since Ive already got an okay indicator of impending stall (the installed stall horn), and Im rarely flying into a situation where dropping the nose and pouring the power on isnt an option - Im much less worried about the stall. Im more worried about the spin that could accompany an uncoordinated stall a spin that may not be recoverable.
My solution:
I built a device that I think can increase situational awareness, specifically coordination awareness. It can do this by taking coordination information out of the instrument panel and placing it in the field of view of the pilot looking outside. It uses LEDs to mimic the motion of the old ball in fluid indicator and can be placed on the glare shield or adhered to the instrument panel so that the pilot can clearly see coordination information at all times. Why do I think this is important? A picture is worth a thousand words:
Here, I'm riding along with my wife and our instructor on a training flight. What's important to note is where her focus is - on the runway. The turn coordinator is circled in red, low in the instrument panel and for all practical purposes, out of view. She's on a stabilized approach, albeit maybe a slightly early turn to final - but if she was really working to get lined up because of wind, distracted by other traffic, or distracted by making sure she turned on the fuel pump on - that turn coordinator would be almost impossible to notice.
Solution: Move coordination information up and into the line of sight, making it practically impossible to ignore.
More technically, the device utilizes a sensitive accelerometer (like the one youd find in your smart phone) to detect coordination. Logic is powered by an ATMEGA 328p 8 bit micro controller, which powers 11 LEDs that illuminate progressively from green, to yellow, to red from 0 degrees to 10 degrees each side, the same way the old inclinometer installed in your turn coordinator becomes progressively out of center. Its powered by two off the shelf AA batteries, and they seem to last about 40 hours or so. As a portable electronic device, it can be moved from aircraft to aircraft and doesnt require any pesky paperwork. Ive also built in a calibration function, so that it compensate for being placed on an unlevel surface (like a glare shield) place it where you want it, center your ball, and click the calibrate button.
Heres a picture taken during an early test flight:
(Not pictured - snap on base. Also using old style LEDs, which were hard to see)
Status of the project:
Ive got a few built and Ive done some basic flight testing on the device and Im happy to report that it works as expected. Ive got some additional testing planned if it would quit storming every afternoon. Ive learned a few things from flight testing, most importantly that the LEDs I was using, while very bright, werent easily visible from the sides. I swapped those out for LEDs that have a more opaque lens thats dimmer, but easier to see from any angle.
Assembly is pretty tedious work since all the components are surface mounted. If I go into even the smallest production run Im going to have to have a manufacturer assemble them for me. See this picture with the old style LEDs:
Who I think could use it:
First and foremost, Im building this for myself and others like me who maybe take coordination a little too seriously.
Past that, I see this as a great training tool for instructors during stall training. Since it uses LEDs its not subject to the parallax of a regular ball indicator and is accurately viewed from any angle.
Request from the forum:
Id like some general feedback from you guys. If flight tests come out ok, Im planning on doing a Kickstarter to fund the first production run. I know that there are some other solutions out there you could buy a secondary ball indicator like these but even those have to be installed and then you get into a whole other issue being that theyre not certified. That, and theyre kind of expensive for what they are. I've even found some options for purpose built portable electronic inclinometers, but their design is similar to the standard style inclinometer, rather than a progressive scale, which I think is an important feature and they seem to lack a calibration function.
Im planning on an early sales price less than $200, driven mostly by the expense of having the circuit boards printed and assembled in relatively small quantities. If demand grows enough, I can likely drive that cost down a good bit by buying in bulk.
My intent isnt to make the next Stratus as much as it is the novelty of having other pilots use something I built and the additional safety factor it could deliver. Though I guess if people would pay $900 each for them and I could sell them like hot cakes, then my flying budget would be a lot better.
Thoughts?
