This is probably the first system in this airplane that I'm not enthralled with. So much complexity, so many things that all have to work perfectly. I've experienced gear problems before, when you're flying and trying to figure out why your gear is not showing down/locked, you want the simplest system possible, with the smallest number of failure modes, that can be easily overridden and manually actuated. A complex logic sequencing system run over CANBus with many potential points of failure does not instill me with confidence. Those small extend and retract latches, with beautiful tight clearances and tolerances that work so perfectly in your tests - what happens when those are contaminated with grease, or dirt, or bugs, or ice? What happens one of the motor sensors fails or mis-reads, and the logic controller drives the motor to extension at full speed? What happens if any of the logic controllers freezes or fails? What happens if any of the wires going to any of the gear gets pinched, shorted, broken? The answer is: gear-up landing, or worse (partial extension landing). In virtually every retractable aircraft I've flown, the default state of the gear is to be down and locked. That means that in most any failure mode, by design, the gear ends up down and locked. The system operates to keep the gear up, and if something fails, the gear comes down. I don't see this functionality in your design: I see multiple different failure modes in your design that result with the gear up and locked with no way of manually overriding it. You also state that the motor load on extraction is 100 watts - that's fine, but what about when it's extending the gear against relative wind in flight? Lastly, if your "gear up and locked" indication is LEDs off, then you need a "push to test" button next to them to illuminate the LEDs and ensure that they are operational, to rule out a failed LED giving a false indication of retracted gear.
Didn’t they show a purely mechanical cable-actuated fall-back solution which lets the gear drop through gravity (edit: and gas springs) in earlier videos? But I don’t know how that’s going to disengage the motors in a reliable way or make sure the latches lock in the down position.
It seems complex but these systems can be incredibly reliable. Steer by wire is coming to cars sold in the US (eg Lexus RZ450e) in which there is no mechanical link between the steering wheel and the front wheels. These systems are also extremely testable and able to provide lots of instrumented feedback at relatively low cost. Given they have a redundant system for emergency deployment, this is probably quite a bit more reliable (if engineered correctly) than it would appear at first sight.
I don't disagree. the controls are interesting, but I want manual overrides. I want fail-down features. Too many light aircraft experience gear failures.
@@mavigogun literally is a one off.. You just don't see the religious parents with millions of dollars backing this. You notice how crystal clean the work/hangers are? The large metal parts are outsourced. I would like to be proven wrong but after 5 years they are still developing landing gear? Like I said before I wish them all the best but this won't work as a business. Who will buy this "kit"?
On the Lancairs, we have a similar gas piston for emergency deployment of our front gear. The mains will fall and lock by themselves. There is a gas pressure decline over time that results in the gas piston not having enough pressure to push the nose gear against the wind all the way until the over center links lock. If this occurs in an emergency, then there is no way around landing without the front gear being locked, and usually results in a prop strike and a scary landing. Owners are urged to routinely cause a deployment to check for this, however it is still happens way more than it should. Here, you have all 3 gear using this method, opening up the possibility of having more than one cylinder fail and not lock at the same time.
How do you replicate the demand on the landing gear that you'd incur in flight? Will you do wind tunnel testing? What about the icing and humidity challenges that mid level and higher altitudes pose?
I've been following this project for a couple years. I'm always blown away by the quality engineering and workmanship. Best of luck in upcoming test flights. Hope it will do everything you want it to. (It will certainly be fast!).
I operated a Baron on a Part 135 certificate. One of the very important preflight items was checking the the gear down locks for grease. If they werent properly visibly externally greasy, the bare metal to metal part can bind when under an air load. Gear that work just fine on the ground can act differently under an air load. Im sure that you guys are already aware of this potential severe problem, some of your viewers may not. In spite of my knowledge of this problem, I had a gear failure on my Baron. I was able to help the sticky gear to break loose by pulling some negative then positive Gs. At the moment that I reversed from negative to positive Gs I hit the gear switch down and they broke loose. The left main gear torque tube had already twisted into a pretzel because the main gear up lock held even though the torque tube was still spinning trying to put both gear down simultaneously. When I didnt get a green on the left main, I made sure that it wast just an indication problem by doing control tower flyby. Then I went out and did my G loading gear assist procedure. (I was schooled on this procedure at the time of purchase by a highly experienced AI Beechcraft mechanic.) The left main gear fell down hard under G loading and clunked into place. I got 3 green the second time I put the gear down. My AI mechanic saved me from a huge repair bill.
Automotive electrical engineer here w/ experience w/ CAN based networks. Love the innovation. Not to be negative Ned here but I'd highly recommend a DFMEA before first flight. What happens if an ESD event takes out your CAN bus? Its not all that unusual in the automotive realm. May want some type of redundancy here. Sorry to throw a dart, just want to make sure your bases are covered.
2:45 Full disclosure, I paused to post this, so I admit I haven't watched the rest... I have been migrating yachts away from direct circuit control to CAN control for over a decade. I am so satisfied to know that you have chosen this route. If it has been good enough for factory automation since the '80s and good enough for the auto industry since the '90s I'm excited to see the reliability and weight savings being applied to the aviation industry by such a forward-thinking group like yours! Kudos... and I look forward to the rest of the video.
Dear DarkAero crew - Green and Red can still confuse a pilot as to up and down, since those colors are port and starboard. And no light means not working or broken. Please use lighted icon symbols indicating Down/Locked or Up/Locked. Thank you. .
many aircraft have the green and red lights for landing gear and it's no issue. There's no common light inside the cockpit I can think of that relies on green and red to indicate port and starboard, those are only the position lights on the wingtips. Icons are fine, but they need to be very easily recognizable at a glance.
Almost every aircraft on the planet has green and red gear indication lights. The only place you see green and red lights indicating port and starboard in aviation is on the navigation lights on the exterior of the aircraft.
As you work through the design, consider ice. Any number of planes have taken off from wet runways and had the water freeze the gear in the up position as the plane climbed to colder conditions. Just something to consider.
The gearbox assembly appears to be sealed, so it's unlikely icing would affect that part of it. The linkages look like they might have the potential to be exposed to some icing, but given how it looks like the linkages nest and articulate, as long as they design it with enough torque, I'd think it could probably break through ice fairly easily (at least on extension if nothing else, retraction might be more problematic in icy conditions). Still, definitely something worth testing.
"Any number of planes have taken off from wet runways and had the water freeze the gear in the up position as the plane climbed to colder conditions." Source?
In general I don't like having the "LED-OFF" state as being the indication is a valid system state. It doesn't allow for the possibility of a malfunction. I think it would be better to have a different color for each position -- 1) up and locked, 2) down and locked, and 3) in-between. With your current system you don't reliably know if a gear is up, or there is a malfunction somewhere. Yes, with LEDs having practically unlimited life, there's little danger of burning one out. However, with your existing indicator system you won't know if the gear is up, or you have a bad LED, or a broken wire, or a bad switch, etc, in your indicator circuitry. You're obviously using Red/Green bi-color LEDs. Why not use Yellow (both on) to indicate one of the states? That might let you get away without any rewiring. Though Red/Green/Blue LEDs would probably look more polished, since Yellow is often an indication of caution. Like you said, "Make your landing gear smarter!" :)) Just my 2-bits...
Not a pilot or engineer, but doesn't preflight checklist cover checking all instruments? I assume the LED's would go through their sequence when starting up (like in a car dashboard). Additionally, if the lights are constantly on while the gears are retracted it'll be super distracting, especially when flying at night. I like their implementation because I'm sure you'd feel/hear the drag if the wheels aren't fully retracted (equivalent to the LED being out as you've mentioned). It's not just the LED that has to malfunction, but also the system. All this is to say that I like their approach; there are indications of what's happening when it's needed, without distractions when not needed.
As someone who specialized on landing gear and flight controls for over a decade, I agree that an off led gives to little information. Maybe look into: Green=down Alternating G/R=gear in transition Red=up LED's are reliable, but not infallible.
@@brois841 Just thinking aloud here, a pre-flight check wouldn't indicate an in-flight system failure. I think the 3-color, never-off concept makes good sense.
@@s14slide I'm definitely not experienced in aircraft, but I really like the idea of a flashing LED indicating movement between valid states. Great idea, and also only changes the software. No additional hardware/wiring required.
It’s amazing how complex some of the systems these guys have built. Pretty amazing to see some highly motivated people working towards the finish of the plane they imagined.
I like the idea of electric power over hydraulic retracts especially on smaller home builts. For one reason, the smaller hydraulic pumps now are almost impossible to get repaired if something goes wrong since Parker decided to condemn their use on aircraft. Also hydraulic systems can get messy at times and in general are more difficult to install compared to wires. Not sure of the eventual cost of this system electric system will be, but if they it is about the same as hydraulic, I would go with the electric, as long as it was adequately tested. And as far as testing is concerned, one thing that caught my attention was the mention of how fast the gear came down due to gravity, compared to how fast it went up. That will be the opposite during flight. The gear will take much more power to come down than it does to go up in this configuration due to drag forces. Your main gear legs have much more drag then say like the Cessna Cardinal RG main gear legs have, which have the same gear swing as your system or Lancair aircraft. There's a reason why many of these RG systems have single tube main gear as opposed to bulkier gear designs like your gear. Two reasons really, weight and air drag. More the drag, the more the power requirement. Your main gear look nice and beefy, but at least 3 times the width of single tube design such as used on a lot of home builts with hyd RG.
One small adjustment I'd recommend from a software/hardware point of view is to have successfully stowed be an illuminated color maybe red. And then in transit be yellow and successfully deployed be green.With this system the pilot can tell the difference between complete gears software/hardware failure(no power) and successful retraction. If this failure were to happen in flight the pilot would have more time to prepare and troubleshoot which could save lives. Great work guys!
The light color logic they're using is standard throughout the GA industry. Green for down, red for somewhere in-between and off for fully retracted. Two colors keeps it simple plus they are easily visually differentiated to know the condition. Adding a yellow would be potentially too close to green and if there is a partial deployment the pilot may mistake the yellow for green, especially if flying with sunglasses or the sun in their eyes, and land with the gear not fully down.
3:19 Rather than autodeploying, it might be preferable to issue an audio warning. At low altitude and airspeed, a sudden change in drag or pitching moment is not always a welcome surprise. Furthermore, each time it autodeploys (especially without warning the pilot), it trains the pilot to forget gear-extension in retractable-gear aircraft.
The light bulb @6:14 is not "100 watt" by any measure. It appears to be an LED lamp, so it doesn't use 100 watts of power; no "100 watt" bulb produces 100 watts of light. I understand the use of a light bulb for the comparison, but to make any sense it has to be an old incandescent bulb that actually uses 100 watts. Since those are generally not used any more, it's not the useful example that it once was.
A long coil-over spring with an oil/gas damper might help to alleviate concerns with the gas spring leaking or failing with age. I know they make similar springs for automotive lift gates that are basically the same geometry as your gas strut, but have a coil over spring around it. Stabilus makes them!
what about aerodynamic forces when in flight and extending the gear, would you test that at some point (I see you're adding gas struts which would make sense to aid against air flow over the gear, would be interesting to see what the power draw is in a simulated in flight extension).
They've already addressed this 100 times. The gas struts are enough to fully extend the landing gear with no motors. That means the power draw when extending gear in flight will be ~nothing.
Killer info and demo! One thing, as per electric vs. hydraulic retract gear system...large passenger jets use almost always hydraulics, except the Boeing 787 which is all electric/electronic.
Any concerns with having radar interfere with the CAN bus? Some cars had to implement extra things for wake-up control due to car batteries going flat at airport parking…
How do you plan for the increased wattage / power requirement to overcome drag when in use real world? Ie. do you know roughly what the additional power requirement would be? Very cool video, thanks for sharing.
Another interesting update! I have zero experience in avionics or aircraft systems but I was suprised at 3:25 when you mentioned _automatically_ extending the gear instead of sounding an alarm and leaving the pilot fully in control. Is that standard, or a departure from what you'd normally expect in a light aircraft?
There have been a few aircraft types that featured interlocking systems extending the gear automatically at full flaps. Personally, I like the idea of an intelligently automated system. It should be better and more flexible than a fixed connection.
I don't want my machine to ever make a configuration change without my input. A warning to the pilot is sufficient. Gear up landings are never a safety problem, but unexpected uncommanded configuration changes have crashed a lot of aircraft over the years. Including airliners.
@@chester8420 would you like a copilot to make saving inputs, if you as PIC happen to miss them? The configuration change could be announced with an option to abort. It doesn't have to be man vs machine.
I want to see the speed of retraction a little faster because this plane is going to accelerate so quickly, it needs to get the gear up out of the wind forces into the wheel wells very quickly. Let’s also see the gear extending with simulated “wind loads” against them, I’m not convinced those little motors can overcome wind stresses over hundred mph, manual emergency extension under wind loads also. Then I’ll be impressed.
Your solution is cool :+ ) Retraction-only motors would be another interesting option; you could solve the soft-extension problem with mechanical design. Couple the retracting motor with a clutch/dog coupling and a ratchet, and you'll have the option to extend the gear during electrical failure. Torque limiters are another elegant way to prevent damage from overdriving an assembly like this; it won't look as graceful as the computer control option, but also doesn't have to involve sensitive electronics of any sort, nor software correctness (take it from a software guy... betting on the correctness of software is a fool's errand), just crude electric limit switches.
Have you given any thoughts about designing a circuit which will allow the landing gear lights perform a flashing mode during transitioning or an unsafe condition?
Will you require any type of ‘weight on wheels’ sensor into the logic unit to prevent any possibility of retraction when on the ground. Looking forward to seeing if the latches used in the locking mechanism require any sort of actuator. Looking really neat. Good luck from the UK
there's actually a move toward full-electric actuation, from what I've seen, as there are no issues with leaking hydraulics, or leaks from incoming fire/shrapnel, and it's easier to use distributed control and monitoring. BTW, I think I'd prefer, personally, that you had amber lights during correct extend/retract cycles, only going to red if a fault is detected... over-current, under-speed, locked /stuck, sensor/feedback failures. Funnily, I was thinking of how simple one could make the functions that you are using a computer to control, with relays (solid-state or not), resistors/potentiometers, switches...a bit more complicated wiring, but operation that anyone with basic electro-mechanical understanding could make work, while still providing the feature set that you have... but, CANbus works fine in cars, and quite robust systems can be designed with CAN/LIN, smart drivers and actuators. Looks good.
Indicator lights off when retracted is a bit of a concern to me. There's no way to distinguish between an indication of normal retracted status and a complete lack of display functionality, since both correspond to lights off. Another colour of each indicator would provide a positive indication of system functionality. The locks are not currently installed. What happens to the indications if a gear extends or retracts all the way, but the lock doesn't engage? Are the locks monitored by position switches?
Do you guys plan on using a weight on wheels switch to prevent pilots from accidentally raising the gear on the ground? I've really enjoyed the aircraft I've flown where this is a feature and its also included an aural tone that alerts the pilot when the gear isn't down after crossing an AoA or Airspeed threshold. That way if the pilot is trying to maneuver the aircraft in a way that would appear to be landing configuration but actually isn't, the gear wouldn't auto-extend and risk being oversped when the pilot completed the maneuver and recovered.
Did you consider pneumatic actuators? Extremely reliable, high forces, relatively small actuators, flexible hoses that are easy to route, push-to-connect fittings, off-the-shelf components, easy to add redundancy, etc.
I just recently saw that a mini turboprop had received or was about to receive certification. Is that something you guys would consider on V2 or V?? Obviously they burn more fuel, but they are crazy light. Wonder if there is some sweet spot with a feather weight plane and power plant. Can't wait to see it fly. You guys are great ambassadors for engineers.
Is "off" as an indicator of closed a good safety option as there's no way to tell the difference between a light circuit malfunction and closed landing gear? I know there have been several industrial accidents stemming from the use of "off" as an indicator, so I'm surprised that it's allowed in aircraft.
For such a small aircraft, a simple pneumatic system is good enough. I think your electric system is too complicated and heavy compared to the pneumatic. What is about free fall system?
How will you be simulating Air Loads on the Gear to validate reliability and function? In the automotive applications, CAN/BUS systems are not user serviceable without OBD type readers. What Service Units will be applicable to this aircraft? While Electro/Servo seems simplest, Electro/Hydraulic may be needed with air Loads. Will watch for development with interest.
Hello guys, Are you intended to use any kind of steering system? Or the turning will be made using differential brake and propulsion? great work, guys! keep it on!
Very cool! Chuckled when you said 100w bulb and then showed an LED! I assume you'll be testing repetitive cycling of gear? What if system fails to deploy...is there any manual action if motors aren't working?
Hydraulics were used because precise control with electric motors had been unreachable until high power MOSFET and IGBT were developed. CAN bus control further reduces weight of electrical drive.
Quick question about your use of OnShape, have they added ITAR/EAR compliance to their systems or if not how are you able to use it for aerospace design?
So what happens when you add in the aerodynamic loads of the plane at approach and landing speeds? It would seem that added load of moving through the air would have a significant force on the components.
How do you test for the wind resistance when lowering the gear at 100 knots let's say? Will the system use a lot more power to overcome the forces of the head wind when lowering the gear during flight?
What redundancy exists in the system in the event of a CAN bus, logic module, or electric motor failure? Will it be possible to manually lower the gear or release the up locks and have them lower by gravity?
Excellent questions. With the depth these lads have plummed in this design we can have confidence that they thought of this, however NONE of that is addressed in this video. They could know their audience better and that we would have these questions.
I like to see simplicity in aircraft. I'm a pilot and the first thing I look at is, what if it does not work? Jammed motor, jammed gear, or no electricity. How will that gear extend and be safe to land? I love new engineering, and also a great critic and available for consulting.
In an earlier video, there's a clutch that disengages a failed motor/gearbox, and a gas strut that pushes the gear down. That part isn't installed in this test series. I expect the gas strut will require regular checks to ensure it hasn't failed.
When the switch is operated, I think I hear two clicks, so it seems like a three-position switch. Is that correct? If so, why is it a three-position switch?
This is a very smart system. I have one question. How much additional power will be required to push against the airflow at maximum landing gear deployment speed?
Yeah, they really need two lights per landing gear. All lights off? Landing gear is up. One (left) light on? In motion. Both lights on? Fully extended, ready to land. (And to +1 other comments, a separate push-and-hold button to verify that the LEDs aren't actually burnt out, as well as piping heat from the engine to the landing gear bays to combat icing-related failures. This is one area of the plane where over-engineering for failure is money/weight well spent. If it were my build, I'd also add cameras to the landing gear bays so I could see what the hell was going on down there in flight.)
This is great to see! Can I ask what kind of system yu are using for the CAN bus? Which CAN bus protocol etc, and do you make your own controllers? In addition, I noticed that the left main landing gear was slower than the right landing gear in both retracting and extending motion, what's the reason for that?
This is probably the first system in this airplane that I'm not enthralled with. So much complexity, so many things that all have to work perfectly. I've experienced gear problems before, when you're flying and trying to figure out why your gear is not showing down/locked, you want the simplest system possible, with the smallest number of failure modes, that can be easily overridden and manually actuated. A complex logic sequencing system run over CANBus with many potential points of failure does not instill me with confidence. Those small extend and retract latches, with beautiful tight clearances and tolerances that work so perfectly in your tests - what happens when those are contaminated with grease, or dirt, or bugs, or ice? What happens one of the motor sensors fails or mis-reads, and the logic controller drives the motor to extension at full speed? What happens if any of the logic controllers freezes or fails? What happens if any of the wires going to any of the gear gets pinched, shorted, broken? The answer is: gear-up landing, or worse (partial extension landing).
In virtually every retractable aircraft I've flown, the default state of the gear is to be down and locked. That means that in most any failure mode, by design, the gear ends up down and locked. The system operates to keep the gear up, and if something fails, the gear comes down. I don't see this functionality in your design: I see multiple different failure modes in your design that result with the gear up and locked with no way of manually overriding it.
You also state that the motor load on extraction is 100 watts - that's fine, but what about when it's extending the gear against relative wind in flight?
Lastly, if your "gear up and locked" indication is LEDs off, then you need a "push to test" button next to them to illuminate the LEDs and ensure that they are operational, to rule out a failed LED giving a false indication of retracted gear.
Didn’t they show a purely mechanical cable-actuated fall-back solution which lets the gear drop through gravity (edit: and gas springs) in earlier videos? But I don’t know how that’s going to disengage the motors in a reliable way or make sure the latches lock in the down position.
It seems complex but these systems can be incredibly reliable. Steer by wire is coming to cars sold in the US (eg Lexus RZ450e) in which there is no mechanical link between the steering wheel and the front wheels. These systems are also extremely testable and able to provide lots of instrumented feedback at relatively low cost. Given they have a redundant system for emergency deployment, this is probably quite a bit more reliable (if engineered correctly) than it would appear at first sight.
@@Mike-oz4cv Hmm. And gas springs are unreliable.
I don't disagree. the controls are interesting, but I want manual overrides. I want fail-down features. Too many light aircraft experience gear failures.
You must have missed the video where they show that the gear motors can be disconnected, and the gear will free-fall with the help of gas struts.
Wish I'd had the fearless ambition of these lads back in the day. This project is truly exceptional.
I'm sure they've had exactly their share of fear. "Courageous ambition", more apt, me thinks.
I wish I was 1/10th as smart as these kids!
Not to be a negative energy but its 5 years and no flight.
@@tbrowniscool this ain't a one-off- progress has been well paced.
@@mavigogun literally is a one off.. You just don't see the religious parents with millions of dollars backing this. You notice how crystal clean the work/hangers are? The large metal parts are outsourced. I would like to be proven wrong but after 5 years they are still developing landing gear?
Like I said before I wish them all the best but this won't work as a business. Who will buy this "kit"?
It's been a while. You guys must be crazy busy, thank you for sharing this journey with us. One of the YT video series I look forward to most!
On the Lancairs, we have a similar gas piston for emergency deployment of our front gear. The mains will fall and lock by themselves. There is a gas pressure decline over time that results in the gas piston not having enough pressure to push the nose gear against the wind all the way until the over center links lock. If this occurs in an emergency, then there is no way around landing without the front gear being locked, and usually results in a prop strike and a scary landing. Owners are urged to routinely cause a deployment to check for this, however it is still happens way more than it should. Here, you have all 3 gear using this method, opening up the possibility of having more than one cylinder fail and not lock at the same time.
How do you replicate the demand on the landing gear that you'd incur in flight? Will you do wind tunnel testing? What about the icing and humidity challenges that mid level and higher altitudes pose?
I've been following this project for a couple years. I'm always blown away by the quality engineering and workmanship. Best of luck in upcoming test flights. Hope it will do everything you want it to. (It will certainly be fast!).
I operated a Baron on a Part 135 certificate. One of the very important preflight items was checking the the gear down locks for grease. If they werent properly visibly externally greasy, the bare metal to metal part can bind when under an air load. Gear that work just fine on the ground can act differently under an air load. Im sure that you guys are already aware of this potential severe problem, some of your viewers may not. In spite of my knowledge of this problem, I had a gear failure on my Baron. I was able to help the sticky gear to break loose by pulling some negative then positive Gs. At the moment that I reversed from negative to positive Gs I hit the gear switch down and they broke loose. The left main gear torque tube had already twisted into a pretzel because the main gear up lock held even though the torque tube was still spinning trying to put both gear down simultaneously. When I didnt get a green on the left main, I made sure that it wast just an indication problem by doing control tower flyby. Then I went out and did my G loading gear assist procedure. (I was schooled on this procedure at the time of purchase by a highly experienced AI Beechcraft mechanic.) The left main gear fell down hard under G loading and clunked into place. I got 3 green the second time I put the gear down. My AI mechanic saved me from a huge repair bill.
Might consider making the service stands and any unique specialty tools / equipment, available to purchasers, once y’all get into production.
Automotive electrical engineer here w/ experience w/ CAN based networks. Love the innovation. Not to be negative Ned here but I'd highly recommend a DFMEA before first flight. What happens if an ESD event takes out your CAN bus? Its not all that unusual in the automotive realm. May want some type of redundancy here. Sorry to throw a dart, just want to make sure your bases are covered.
2:45 Full disclosure, I paused to post this, so I admit I haven't watched the rest...
I have been migrating yachts away from direct circuit control to CAN control for over a decade. I am so satisfied to know that you have chosen this route.
If it has been good enough for factory automation since the '80s and good enough for the auto industry since the '90s I'm excited to see the reliability and weight savings being applied to the aviation industry by such a forward-thinking group like yours!
Kudos... and I look forward to the rest of the video.
Another great video guys! Well done so far and we are all (of course) excited to see the upcoming maiden!
Dear DarkAero crew - Green and Red can still confuse a pilot as to up and down, since those colors are port and starboard. And no light means not working or broken. Please use lighted icon symbols indicating Down/Locked or Up/Locked. Thank you. .
I'd assume you can easily customise that to your taste, no biggie
@@josephc.9520 Some will forget that -> will be a biggie.
Better to make it fool proof by DA
many aircraft have the green and red lights for landing gear and it's no issue. There's no common light inside the cockpit I can think of that relies on green and red to indicate port and starboard, those are only the position lights on the wingtips. Icons are fine, but they need to be very easily recognizable at a glance.
Almost every aircraft on the planet has green and red gear indication lights. The only place you see green and red lights indicating port and starboard in aviation is on the navigation lights on the exterior of the aircraft.
As you work through the design, consider ice. Any number of planes have taken off from wet runways and had the water freeze the gear in the up position as the plane climbed to colder conditions. Just something to consider.
The gearbox assembly appears to be sealed, so it's unlikely icing would affect that part of it. The linkages look like they might have the potential to be exposed to some icing, but given how it looks like the linkages nest and articulate, as long as they design it with enough torque, I'd think it could probably break through ice fairly easily (at least on extension if nothing else, retraction might be more problematic in icy conditions). Still, definitely something worth testing.
Wow good call @marcericdavis. Totally didn't even think of that.
"Any number of planes have taken off from wet runways and had the water freeze the gear in the up position as the plane climbed to colder conditions."
Source?
I can't wait to see this thing fly! I hope you live stream it!
In general I don't like having the "LED-OFF" state as being the indication is a valid system state. It doesn't allow for the possibility of a malfunction. I think it would be better to have a different color for each position -- 1) up and locked, 2) down and locked, and 3) in-between. With your current system you don't reliably know if a gear is up, or there is a malfunction somewhere.
Yes, with LEDs having practically unlimited life, there's little danger of burning one out. However, with your existing indicator system you won't know if the gear is up, or you have a bad LED, or a broken wire, or a bad switch, etc, in your indicator circuitry. You're obviously using Red/Green bi-color LEDs. Why not use Yellow (both on) to indicate one of the states? That might let you get away without any rewiring. Though Red/Green/Blue LEDs would probably look more polished, since Yellow is often an indication of caution.
Like you said, "Make your landing gear smarter!" :)) Just my 2-bits...
Agreed. LED off should only indicate a failure or power-off state. Red/Yellow/Green has been a standard for decades for a reason.
Not a pilot or engineer, but doesn't preflight checklist cover checking all instruments? I assume the LED's would go through their sequence when starting up (like in a car dashboard). Additionally, if the lights are constantly on while the gears are retracted it'll be super distracting, especially when flying at night. I like their implementation because I'm sure you'd feel/hear the drag if the wheels aren't fully retracted (equivalent to the LED being out as you've mentioned). It's not just the LED that has to malfunction, but also the system.
All this is to say that I like their approach; there are indications of what's happening when it's needed, without distractions when not needed.
As someone who specialized on landing gear and flight controls for over a decade, I agree that an off led gives to little information. Maybe look into:
Green=down
Alternating G/R=gear in transition
Red=up
LED's are reliable, but not infallible.
@@brois841 Just thinking aloud here, a pre-flight check wouldn't indicate an in-flight system failure. I think the 3-color, never-off concept makes good sense.
@@s14slide I'm definitely not experienced in aircraft, but I really like the idea of a flashing LED indicating movement between valid states. Great idea, and also only changes the software. No additional hardware/wiring required.
It’s amazing how complex some of the systems these guys have built. Pretty amazing to see some highly motivated people working towards the finish of the plane they imagined.
I recognize those CIM style motors/Gearbox anywhere lol (We used them a lot in FRC) 0:01
I like the idea of electric power over hydraulic retracts especially on smaller home builts. For one reason, the smaller hydraulic pumps now are almost impossible to get repaired if something goes wrong since Parker decided to condemn their use on aircraft. Also hydraulic systems can get messy at times and in general are more difficult to install compared to wires. Not sure of the eventual cost of this system electric system will be, but if they it is about the same as hydraulic, I would go with the electric, as long as it was adequately tested. And as far as testing is concerned, one thing that caught my attention was the mention of how fast the gear came down due to gravity, compared to how fast it went up. That will be the opposite during flight. The gear will take much more power to come down than it does to go up in this configuration due to drag forces. Your main gear legs have much more drag then say like the Cessna Cardinal RG main gear legs have, which have the same gear swing as your system or Lancair aircraft. There's a reason why many of these RG systems have single tube main gear as opposed to bulkier gear designs like your gear. Two reasons really, weight and air drag. More the drag, the more the power requirement. Your main gear look nice and beefy, but at least 3 times the width of single tube design such as used on a lot of home builts with hyd RG.
This project looks so good in white. Well done boys.
One small adjustment I'd recommend from a software/hardware point of view is to have successfully stowed be an illuminated color maybe red. And then in transit be yellow and successfully deployed be green.With this system the pilot can tell the difference between complete gears software/hardware failure(no power) and successful retraction. If this failure were to happen in flight the pilot would have more time to prepare and troubleshoot which could save lives. Great work guys!
The light color logic they're using is standard throughout the GA industry. Green for down, red for somewhere in-between and off for fully retracted. Two colors keeps it simple plus they are easily visually differentiated to know the condition. Adding a yellow would be potentially too close to green and if there is a partial deployment the pilot may mistake the yellow for green, especially if flying with sunglasses or the sun in their eyes, and land with the gear not fully down.
100k subs
congrats !
Just curious but why didn't you guys use a tail-dragger design for the landing gear? Wouldn't it be lighter and simpler?
3:19 Rather than autodeploying, it might be preferable to issue an audio warning. At low altitude and airspeed, a sudden change in drag or pitching moment is not always a welcome surprise. Furthermore, each time it autodeploys (especially without warning the pilot), it trains the pilot to forget gear-extension in retractable-gear aircraft.
Will you eventually add fairings/doors to cover the landing gear while retracted?
Yeah they did make some in an earlier episode
The light bulb @6:14 is not "100 watt" by any measure. It appears to be an LED lamp, so it doesn't use 100 watts of power; no "100 watt" bulb produces 100 watts of light. I understand the use of a light bulb for the comparison, but to make any sense it has to be an old incandescent bulb that actually uses 100 watts. Since those are generally not used any more, it's not the useful example that it once was.
How far aft does the CG move when the gear retracts?
Nice work.
Try to avoid "off" LED's as you do not know whether the LED is broken, without power or in the stored position.
I agree- a color to indicate retracted would be ideal
A long coil-over spring with an oil/gas damper might help to alleviate concerns with the gas spring leaking or failing with age. I know they make similar springs for automotive lift gates that are basically the same geometry as your gas strut, but have a coil over spring around it. Stabilus makes them!
what about aerodynamic forces when in flight and extending the gear, would you test that at some point (I see you're adding gas struts which would make sense to aid against air flow over the gear, would be interesting to see what the power draw is in a simulated in flight extension).
They've already addressed this 100 times. The gas struts are enough to fully extend the landing gear with no motors. That means the power draw when extending gear in flight will be ~nothing.
@@JH-tc3yu what's the rating on the struts? (it was probably mentioned but I missed those 100 vids where it was explained)
We are huge fans of this crew.
What is your back up for a failed motor or electrical system?
Awesome system! Thanks for sharing
Killer info and demo! One thing, as per electric vs. hydraulic retract gear system...large passenger jets use almost always hydraulics, except the Boeing 787 which is all electric/electronic.
…congrats on 100K…Please, accept this virtual “high-five” 🖐🏻
Glad to see you got rid of the gas struts. Really impressed with the progress!!
Congrats on 100k!
Any concerns with having radar interfere with the CAN bus? Some cars had to implement extra things for wake-up control due to car batteries going flat at airport parking…
Related to airport parking or just general long term parking? 🤔
@@TheStuartstardust airport parking. The radar pulse would wake up the CAN bus.
100K! Congrats
this is quite possibly the most challenging part of the whole build executed like industry experts.
How do you plan for the increased wattage / power requirement to overcome drag when in use real world? Ie. do you know roughly what the additional power requirement would be? Very cool video, thanks for sharing.
Bravo Dark Aero Team, bravo
Another interesting update! I have zero experience in avionics or aircraft systems but I was suprised at 3:25 when you mentioned _automatically_ extending the gear instead of sounding an alarm and leaving the pilot fully in control. Is that standard, or a departure from what you'd normally expect in a light aircraft?
There have been a few aircraft types that featured interlocking systems extending the gear automatically at full flaps.
Personally, I like the idea of an intelligently automated system. It should be better and more flexible than a fixed connection.
I don't want my machine to ever make a configuration change without my input. A warning to the pilot is sufficient. Gear up landings are never a safety problem, but unexpected uncommanded configuration changes have crashed a lot of aircraft over the years. Including airliners.
@@chester8420 would you like a copilot to make saving inputs, if you as PIC happen to miss them?
The configuration change could be announced with an option to abort. It doesn't have to be man vs machine.
Good lord I can't wait for this beast to fly!
What's the airspeed where the electrical actuators can't achieve deployment against the airflow?
I want to see the speed of retraction a little faster because this plane is going to accelerate so quickly, it needs to get the gear up out of the wind forces into the wheel wells very quickly. Let’s also see the gear extending with simulated “wind loads” against them, I’m not convinced those little motors can overcome wind stresses over hundred mph, manual emergency extension under wind loads also. Then I’ll be impressed.
Your solution is cool :+ )
Retraction-only motors would be another interesting option; you could solve the soft-extension problem with mechanical design. Couple the retracting motor with a clutch/dog coupling and a ratchet, and you'll have the option to extend the gear during electrical failure. Torque limiters are another elegant way to prevent damage from overdriving an assembly like this; it won't look as graceful as the computer control option, but also doesn't have to involve sensitive electronics of any sort, nor software correctness (take it from a software guy... betting on the correctness of software is a fool's errand), just crude electric limit switches.
Have you given any thoughts about designing a circuit which will allow the landing gear lights perform a flashing mode during transitioning or an unsafe condition?
Happy 100k!!!!!🥳🍾🎊🎉🍻
Thanks for another well produced and really informative/interesting video. You guys amaze me.
Will you require any type of ‘weight on wheels’ sensor into the logic unit to prevent any possibility of retraction when on the ground. Looking forward to seeing if the latches used in the locking mechanism require any sort of actuator. Looking really neat. Good luck from the UK
Unbelievable what you have achieved so far.
Speaking from personal experience with hydro. One less system to cover in hydro is a win. If the electric motor is reliable I say go for it.
I can't wait for this to fly in 2047!
It's actually much more common to find the landing gear in model planes driven by pneumatics.
there's actually a move toward full-electric actuation, from what I've seen, as there are no issues with leaking hydraulics, or leaks from incoming fire/shrapnel, and it's easier to use distributed control and monitoring.
BTW, I think I'd prefer, personally, that you had amber lights during correct extend/retract cycles, only going to red if a fault is detected... over-current, under-speed, locked /stuck, sensor/feedback failures.
Funnily, I was thinking of how simple one could make the functions that you are using a computer to control, with relays (solid-state or not), resistors/potentiometers, switches...a bit more complicated wiring, but operation that anyone with basic electro-mechanical understanding could make work, while still providing the feature set that you have... but, CANbus works fine in cars, and quite robust systems can be designed with CAN/LIN, smart drivers and actuators.
Looks good.
CAN/Bus is also extensively used in commercial aircraft, I think in many military aircraft as well.
Indicator lights off when retracted is a bit of a concern to me. There's no way to distinguish between an indication of normal retracted status and a complete lack of display functionality, since both correspond to lights off. Another colour of each indicator would provide a positive indication of system functionality.
The locks are not currently installed. What happens to the indications if a gear extends or retracts all the way, but the lock doesn't engage? Are the locks monitored by position switches?
Do you guys plan on using a weight on wheels switch to prevent pilots from accidentally raising the gear on the ground? I've really enjoyed the aircraft I've flown where this is a feature and its also included an aural tone that alerts the pilot when the gear isn't down after crossing an AoA or Airspeed threshold. That way if the pilot is trying to maneuver the aircraft in a way that would appear to be landing configuration but actually isn't, the gear wouldn't auto-extend and risk being oversped when the pilot completed the maneuver and recovered.
Did you consider pneumatic actuators? Extremely reliable, high forces, relatively small actuators, flexible hoses that are easy to route, push-to-connect fittings, off-the-shelf components, easy to add redundancy, etc.
I just recently saw that a mini turboprop had received or was about to receive certification. Is that something you guys would consider on V2 or V?? Obviously they burn more fuel, but they are crazy light. Wonder if there is some sweet spot with a feather weight plane and power plant. Can't wait to see it fly. You guys are great ambassadors for engineers.
Is "off" as an indicator of closed a good safety option as there's no way to tell the difference between a light circuit malfunction and closed landing gear? I know there have been several industrial accidents stemming from the use of "off" as an indicator, so I'm surprised that it's allowed in aircraft.
For such a small aircraft, a simple pneumatic system is good enough. I think your electric system is too complicated and heavy compared to the pneumatic.
What is about free fall system?
What controllers are you using for the CAN BUS system?
Are you using vexpro aluminum gears?
How will you be simulating Air Loads on the Gear to validate reliability and function?
In the automotive applications, CAN/BUS systems are not user serviceable without OBD type readers.
What Service Units will be applicable to this aircraft?
While Electro/Servo seems simplest, Electro/Hydraulic may be needed with air Loads.
Will watch for development with interest.
How much does the cg move when the gear is retracted?
I'm getting Cessna 337 vibes from the rears 😀
Hello guys,
Are you intended to use any kind of steering system? Or the turning will be made using differential brake and propulsion?
great work, guys! keep it on!
how do you make sure that off lights don't mean the light is broken? wouldn't a blue color be more useful when the gear is retracted?
Many aircraft have a push-to-test button than illuminates all annunciators on the panel to check for burned-out bulbs. Maybe they'll incorporate one?
Needs ground proximity sensor …. How does the panel know if altitude at any runway or off runway excursions… ref. Emergency extend / retract
Very cool! Chuckled when you said 100w bulb and then showed an LED! I assume you'll be testing repetitive cycling of gear? What if system fails to deploy...is there any manual action if motors aren't working?
thanks to the shout out to the ole 727 landing gear.
The nice thing about fixed gear is there always locked down and higher than ten thousand feet not that much drag!
Whats the maximum gear extension retraction speed?
Hydraulics were used because precise control with electric motors had been unreachable until high power MOSFET and IGBT were developed. CAN bus control further reduces weight of electrical drive.
How do you test that there is enough power in the gear extension mechanism to overcome the wind resistance in flight?
Are you using a absolute encoder at the main gear arm for feedback? What kind of feedback control are you using for the speed control? PID?
Is there a sensor to only allow retract when the plane is sitting on the ground? I didn't see it in the wiring diagram. Maybe it will come later.
so the "Drag Link" in the main gear is in tension?
Will you have wheel bay doors that close to aid aerodynamic flow?
have you done a with and balance with the wheels up, and down ? , as it looks like? it may? shift the c/g ,
did you use CANaero protocol or CANbus ?
Thinking from a systems safety/failure modes analysis: How is “off” an indication of anything other than an open circuit?
I hope the mains the way they deploy, I hope it has a STRONG locking mechanism
Quick question about your use of OnShape, have they added ITAR/EAR compliance to their systems or if not how are you able to use it for aerospace design?
Was that a vex pro gearbox?
Because that looks like a versa-planetary gearbox powered by a BAG Motor
Bravo.Go Ahead
Landing gear is a Garmin wacume cleaner piston back wards?
Es perfecto ..felicidades ..
Exelente trabajo
So what happens when you add in the aerodynamic loads of the plane at approach and landing speeds? It would seem that added load of moving through the air would have a significant force on the components.
Awesome stuff!!
May I ask what is the weight of the main wheel-tire-shock absorber and the front wheel-tire-shock absorber?
Are the linear motors stock? It's a nice and smooth running system.
Is it possible to build such a landing gear with CAN BUS control?
Will the landing gear have doors which close around the retracted landing gear in flight to reduce drag ?
How do you test for the wind resistance when lowering the gear at 100 knots let's say? Will the system use a lot more power to overcome the forces of the head wind when lowering the gear during flight?
What redundancy exists in the system in the event of a CAN bus, logic module, or electric motor failure? Will it be possible to manually lower the gear or release the up locks and have them lower by gravity?
Excellent questions. With the depth these lads have plummed in this design we can have confidence that they thought of this, however NONE of that is addressed in this video. They could know their audience better and that we would have these questions.
They literally mentioned their emergency extend system in the video.
I like to see simplicity in aircraft. I'm a pilot and the first thing I look at is, what if it does not work? Jammed motor, jammed gear, or no electricity. How will that gear extend and be safe to land? I love new engineering, and also a great critic and available for consulting.
In an earlier video, there's a clutch that disengages a failed motor/gearbox, and a gas strut that pushes the gear down. That part isn't installed in this test series. I expect the gas strut will require regular checks to ensure it hasn't failed.
Under what G-loading (positive and negative) does the gear-retract/extend system work reliably?
When the switch is operated, I think I hear two clicks, so it seems like a three-position switch. Is that correct? If so, why is it a three-position switch?
This is a very smart system. I have one question. How much additional power will be required to push against the airflow at maximum landing gear deployment speed?
Very elegant! I'm not red/green colorblind, but I'm curious if the red/green landing gear LEDs offer enough color differentiation for those that are?
Yeah, they really need two lights per landing gear. All lights off? Landing gear is up. One (left) light on? In motion. Both lights on? Fully extended, ready to land. (And to +1 other comments, a separate push-and-hold button to verify that the LEDs aren't actually burnt out, as well as piping heat from the engine to the landing gear bays to combat icing-related failures. This is one area of the plane where over-engineering for failure is money/weight well spent. If it were my build, I'd also add cameras to the landing gear bays so I could see what the hell was going on down there in flight.)
This is great to see! Can I ask what kind of system yu are using for the CAN bus? Which CAN bus protocol etc, and do you make your own controllers?
In addition, I noticed that the left main landing gear was slower than the right landing gear in both retracting and extending motion, what's the reason for that?