Why we designed our own retractable landing gear
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- čas přidán 14. 07. 2024
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0:00 - Intro
1:49 - Main Gear Overview
4:04 - Gearbox Design
4:51 - Emergency Extension
6:00 - Gearbox Fabrication
7:12 - Why build our own?
7:57 - Next Steps
In this video, we discuss one of the major tasks we've been focused on lately leading up to flight testing, which is our retract system for the main landing gear.
If you enjoyed this video and would like to see more of this type of content, follow along as we work to create the fastest, longest-range aircraft you can build in your garage!
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Understanding the aero forces is critical. There will be a max airspeed where gear 'freefall' doesn't happen. That'll be part of your ODM. I, like others commenting, also believe the gas strut is not overly sound in terms of reliability. I also concur with a previous comment re unlocking, this needs to be a very robust and simple mechanism. No doubt this is designed with failure modes understood, and likelihood of combined failures etc. but the gas strut sees all the same temp. changes, is exposed, and sees cycles with the gear every time, regardless of when its needed in an emergency. Its preferable to have freefall / emerg. unlock systems designed to not see all that.
I am not a fan of the open exposed 'half gear'. I don't think it would take much from tyre and runway detritus or other debris to maybe give that a problem in normal retract or extend, but especially emerg. extend where its only the gas strut and gear mass doing the work. Go look at how dirty a used aeroplane undercarriage bay can be.
Be very clear and do many many assessments of the effects of aero loads on retract and extend. I have commented before on this here. Airloads will catch up any backlash, and then the system will catch up, then the airloads catch up, ad nauseam. Wears things out quickly. Gear cycles are greatly affected by this even at low air speeds. What are the target times for up and down cycles? These should be derived from airspeed increase / decrease rates on take off / landing. Again, another set of limits that go into an ODM. I am very impressed by the effort and detail of this design, but do also think that some more failure and wear studies / tests are appropriate particularly with the gear. Good luck and keep working hard! (and feel free to contact me any time (42 years in aircraft design, manuf. and maint. of 330kts, +6-3g aeroplanes). I'd enjoy a good discussion, and would love to help you make sure this becomes the best home build light aeroplane.
The problem with what you're proposing about using something that doesn't see wear and tear with the normal landing gear cycles is it would by mechanical default have to be disconndected until it's needed. And that adds complexity and therefore, failure points. Because there's no guarantee your gear will be in an exact position to re-link the emergency option when you actually need it. As for the half gear, I was half paying attention to what was being said and paying a lot of attention to what was being shown. Probably aluminum. I would have to see their gear meshing tolerances before making a judgement. But I'd want it to be a bit beefier and with a proper case. But I can see the design challenges of that case, and if I'm to be honest. Leaving it that open does leave it harder to jam than a case with poor tolerances. The gears should be able to take hits from stuff like gravel and such and still be fine. Maybe double check that the gear teeth don't come within 1/4-1/2 inch of the gearbox housing except for the sides. Give it a slight cover in the areas where something is most likely to land and go into the gears. Should be good. It'll get dirty but the important part is with that kinda stuff it would be very unlikely to jam. Probably fairly easy to wash, too. As for the gas spring things I'd say do regular check ups. Replace after x amount of flights. Seems to be in a very easy to access spot to do just that, so it was probably their intention for a while.
No experience designing aircraft. Just grew up tinkering and pretty familiar with gearbox annoyances and spring wear and tear. I'd like to design my own aircraft at some point though
@@hf117j
I’m looking forward to seeing the plane in the sky! Who is waiting for the plane presentation on Oshkosh?
When's that
That's gonna be awesome. I bet this will be a hit there, for sure.
Very interesting video. Knowing from experience that gear failures are one of the most common failures you get on complex aircraft, failure mode planning and analysis is always of interest to me. With that in mind...gear switch failures are common. What is the failure mode (i.e. the weak link) should an up or down limit switch fail, and the actuator continues to run - does it stop against a physical limit? Does the clutch let go? What causes the drag links to overextend? I don't see a spring in there anywhere. Also, what actuates the up/down lock mechanism, and what is the override to unlock the gear should that mechanism fail in flight?
I always found it fascinating when studying gear systems, that the design is typically "the ability to retract is optional, but the system will move heaven and earth to extend the gear." In that in any given failure mode, the default is to end up with the gear down and locked. Witness hydraulic systems which utilize continuous pressure to keep the gear retracted - loss in pressure for any reason causes the gear to free fall. Things like a mechanical uplock (obviously required in your design due to the actuator) make me nervous unless I know there is something I can do that will absolutely release that lock in the event of some kind of damage and/or failure.
With that in mind - is there a blow-down or other emergency extension method if there is a mechanical failure of the actuator gearbox? I'd hate to have a gear up landing because of a sheared/jammed pinion tooth.
To piggyback on this comment, gas struts are known failure points, especially in cold temperatures when the seals harden. So I would be somewhat concerned about using a compressed gas strut as the failure extension driver. One other thing, can you discuss what inspections the builder/pilot should perform on the gear retract/extension systems? For example, to confirm that the up- and down- locking latches are not worn out of tolerance?
Piggy backing even further: I would consider a torsion spring rather than a gas strut, to address those failure modes. The metallurgy should be consistent enough that you should be able to calculate a mean cycles to failure, and thus have a flight cycles to replacement spec.
I always love such positive criticism.
The gas strut which handles extension in case of gearbox motor failure is described in the video. If the gearbox mechanically jams, you're doing a belly landing.
5:50 That drag link looks like it will be highly loaded during an emergency braking event.
The transparency that you guys operate with in this design phase definitely helps engender trust for both your designs and brand. It's great to see you operate like this
Its because they arnt doing anything new
@@philipdrew10 yeah you're right mate, other than being a new company and designing a brand new GA aircraft in a mostly aluminium and fibreglass aircraft world. When you look at the smaller features in the aircraft too there are elements of innovation throughout. Maybe this is nothing in comparison to your own achievements and you have ground up designed an aircraft or potentially even have built and flown a kit aircraft but even if you have, I wouldn't belittle their achievements to make yourself feel better about yourself. It's easy to criticise from our armchairs and far harder to do. Three brothers in a newly formed company which appears to be self funded apparently on track to deliver on their promises, this isn't SpaceX mate.
Great work guys to reduce passive weight and make your own solution. However gas struts as a redundant mechanism concern me. You also have no way of checking the gas strut condition after it has been installed, it will always look the same in checks same but how do you know if the preload is still there?
This is one of my questions as well. Even if it was just inspected and found to be serviceable, it will fail at some point, and how will you know on a walk around?…
Your composites course was a 10! Please do a follow-on course on machining and mold-making. You guys are the best, thank you
Thank you for taking the Aerospace Composites Course! We have an in-person Aerospace Mold Making Course, and an online version is coming shortly as well!
The gas spring idea is good because it will help the motor push the gear down against drag while you are coming in for a landing, and the air will help compress the gas spring working with the motor on the way up after taking off. However gas springs are notorious for leaking, and without feeling it by hand with the plane held off the ground I see no way to check the spring force of it to make sure it's still working. If it were to leak and fail, it would cause the electric motor to have to endure much higher load during normal use, potentially causing that to fail as well. I would want a filling port on it or a strain gage on the mounting bracket or some way to verify they are working as part of the pre-flight
Yes. That gas spring could be an issue.... at exactly the wrong time.
I hate gas struts for his exact reason. Have replaced many on various vehicles and campers. If they were on my airplane I would replace them every 6 months or so to ensure they haven’t failed
Yeah as soon as I saw that my head remembered all the times I have wacked it on my trunk hatch because it was not up all the way in cold weather. A mechanical spring of some sort would make me much happier. I would move heaven and earth to avoid that gas shock if I was building this myself.
Looking forward to that nose gear dop test!
Why not do a simple pneumatic actuation system? Replace the gas strut with a double acting cylinder and make the up lock pneumatically actuated. A 14 gram CO2 bottle with a piercing valve would be your emergency blow down. Engine driven or 12v mini compressor, mechanical valve, and some indicator lights would be all you need.
I like the emergency blow down idea, but I feel like there needs to be a way to manually pump the gear down as well. Adding a small pump with a lever arm would only add minimal weight.
@@joetroyner Yes that is an option. The Piper Aztec I've worked on is hydraulic off one engine, hydro hand pump backup, and an emergency CO2 blow down bottle as a last resort. To keep weight to a minimum just a CO2 bottle and primary system should be adequate if properly designed. On something like the Aztec the backup hand pump can also lower the flaps and raise the gear if needed during single engine operation.
also those gas struts might be fine in the lower 48 but i've never seen one of those gas struts last more then a year at < -20F here in alaska, the cold just wrecks the seals and lets the gas out every winter. i'd imagine you could potentially have the same problem at cold temps at altitude even in areas with much higher ground temps. at cold temps even when they do have some gas left in them the pressure is so low that the piston looses all its force. by -40F they have no force at all or the seals shrink so much the gas is gone.
when i finaly have enough money saved up to build a dark aero i will have to come up with my own solution for here in the north. i dont see a reason a simple spring piston instead of a gas piston wouldn't work. it would weigh a bit more but the gas cant leak out of a spring.
Reliability and simplicity should be design criteria.
I’m not keen on increasing the number of systems that are not testable.
I like flaps controlled by a simple mechanical lever. Lever position = flaps position.
If I had to pull a lever to drop gear and pump it three times to ratchet the gear into place for every landing, I’d be fine with that, especially if I didn’t have to move my head. Electric retraction is great as long as the lever always drops and extends; but for such lightweight gear, I don’t know that it’s necessary.
Thanks for the update. The aircraft is developing nicely.
Thanks for the update, guys. That's really smart and elegant solution! Excellent work, gentlemen.
That landing gear has been a beast for you guy’s. It’s inspiring to see you take on these challenges with such positive innovative persistence.
Looking forward to seeing your continued progress!
Why did you not use the mechanical advantage of driving the locking strut to move the gear rather than the main arm?
I thought about that too, but it actually has a pretty bad advantage in the fully retracted state.
The force being applied on the pinion teeth must be pretty large.
Gas springs have a very high failure rate. Is there a higher quality gas spring type you are using for emergency gear lock?
That gearbox looks amazing 🤩 cheers guys! I love this project !!!
Another awesome solution to a complex problem. You guys really rock!
Very exciting, guys. I wonder if you guys ever went over to Boeing Surplus in Kent near South Center Mall area? It's not there anymore but back in the day you could buy sheets of titanium and nose cones from B-52s and rows of old passenger plane seats from 707s and even older Boeing builds. The 10x10' bin of used drill bits sold by the pound was also great and I still have some of em which were used like twice before the tolerances were shaved down and all are made of cobalt or titanium which i think i got for like 10 bucks for a couple pounds of em! I have a Rand-McNally world map they had in war rooms from WWII and a metal desk that weighs like 2 tons! Its no longer there but you could have likely sourced half those parts right in bins there what an amazing resource that place was
Thank you TRUE AMERICAN
@@stevefisher2553 Thanks LOL all from a schpiel about used boeing parts (i'll take it!) carry on, good citizen!
Great review guys! Good to see the progress.
Details, details, details. Keep pushing! You're getting closer to first flight!
I’ve been waiting for this vid!
Thanks for the update. Appreciate the in-depth explanations.
Great content guys! And I cannot wait to see your beautiful aircraft up in the sky!!
Really, all of the most beautiful and sleek and simple aspects of a small plane all into one on this. And lightweight carbon fiber. Two seater. Nice space for cargo. Great engine. Tricycle landing gear. This plane is so awesome.
Well done ..thank you for sharing
I love that they are using a neo550 and versa planetary, it's kind of weird to see it in this application.
wait are you planning on using a spark max controller or something like a vesc. In either case why do you want to be using a sensored motor, I would think with having endstops you could just use a simple esc and ignore the sensored aspect to reduce complexity and cost.
@@shuki546 they are using a bldc? Yikes. It seems like they should just use a brushed motor. I agree with you about ignoring sensors.
Excellent stuff bro
Excellent presentation style, and really interesting problem solving. Keep up the good work boys!
I'm intrigued that the landing gear retract towards the tail. Given the limited space there really isn't another way, but for emergency gear release, in most planes the gear retract forward so that when they are dropped with gravity they are assisted by drag rather than prevented or the drag resisting the gear dropping. But I like the simple solution
More amazing work guys!
How do you know if a gas strut for emergency extension goes bad and leaks out all the pressure? How about operation in cold weather?
Inspections
@@9HighFlyer9 should be something you can verify on a walk around no?
@@9HighFlyer9 but how do you inspect the struts, without removing one end? That's possible, but not something that I would want to do for every flight.
@@jdomarsh yeah, I mean a walk around is just a mostly visual inspection. As long as the strut doesn't have any obvious damage, not leaking oil or sagging I'd say that's an adequate inspection.
@@9HighFlyer9 they could be completely inop without any visual indicators. Considering theres 3 possible failure points for the fear system ie the gear motor, gear box and the electrical system itself it would probably be good to have something you can check before each flight. Maybe if they had an external pressure gauge that could be verified or just a hand crank for a manual extension in emergency purposes that would make more sense to me. Just my 2 cents
Good work lads. Keep it up
Awesome project!! You guys are doing this right!! Make haste slowly!!
I look everyday for your videos. Awesome
Very nice work!
this is such an awesome plane. i want one.
Looks great guys! Question on the back up gas spring: it’s fully passive as is, would it not be better to have a pneumatic cyl that you can hand pump from the cockpit? Pilots like to be in control. 😂
That’s an interesting idea. The advantage there would be the drive motor wouldn’t have to work against the gas spring. The pneumatic cylinder would be along for the ride until you need it. The disadvantage would be the increased part count and plumbing associated with the system. 🤔
@@DarkAeroInc Im an aero eng with a habit of throwing ideas everywhere and seeing what sticks. HAHAHA and I LOVE the plane! You guys are knocking it out of the park! I will be visiting when I get more money for sure.
@@DarkAeroInc Armchair expert here. Would it be feasible to have a cable attached to the drag link to pull it up towards the gear pivot. That cable could somehow be hand actuated in the cockpit in an emergency. An issue I can foresee with that is how do you make a cable not interfere with normal gear operation. Would it possible to sideslip and rock the gear into the down and locked position? If not would an aerodynamic feature on the gear be able assist a sideslip extension.
What a fun engineering challenge you guys have.
Would driving the drag link instead of the strut reduce the force required from the actuator? This build series is one of the best on CZcams. I can’t get enough your detailed explanations. Great work!
no, it won't
Soo...how are you going to ensure that the gas strut seals haven't blown out?
I mean, practically, how are you going to pre-flight verify that they'll work?
You could replace them at annual or find a rebuildable/rechargeable alternative I suppose.
I have a boat with a power bimini roof using a very similar actuator. I needed to wire a special fuse that pops and resets the actuators.
The projects just keeps getting more interesting. Can't wait for the first flight, but a lot of it depends on the performance of the landing gear. Hopefully, the drop tests, taxing, and post flight reveal that you came up a with a good design. I can imagine a few tweaks here and there, but great job regardless.
Excellent!
The landing gear system is nearly the same movement as a garage door. I would use a garage door spring to deploy the landing gear when unpowered and help fight aero drag.
I think both side of the landing gear could be mechanicly linked and have one actuator, there is no point having one side work but not the other in case of failure.
Suspension doesn't look like it has much travel.
Great job 👍🏻
Great design....but, if I may suggest an alternative idea for the Emergency system;
The use of the "Emergency compressed gas piston" is going to add a lot of stress on the gear motor, especially when it gets towards the end of the "gear up" cycle for 2 reasons;
1 maximum amount of compression thusly increased pressure
2 loss of aerodynamic advantage. At the beginning of the up cycle w/ all of that aerodynamic force, it's easy for the motor to move gear (even when the piston pushing the gear) but at the top of cycle, you lose the aerodynamic pressure and you're fighting the gas compression- putting a lot of stress on the motor & gear teeth. Not saying the motor can't deal with the forces, just saying the intentionally lightweight components are going to be working in a "max effort" configuration.
AN ALTERNATIVE solution might be to pull the gear in an emergency. We understand that the disengaged clutch and the release of the mechanical up lock will allow gear free fall; all we need to do is extend gear pass the point of aerodynamic resistance, right? This is where Emer Proc is crucial; free fall of gear requires speed reduction to X before attempting. At this reduced speed (thus reduced force) the gear could be "pulled" forward by cable or worm gear from the cockpit by manual crank or electric motor.
The gas compressed strut is an elegant solution but I fear the added stress on the gear motor and gears might result in a long-term maintenance issue.
I love watching your videos, wish I was there! How rewarding it must be to design novel answers for a true 21st Century Aircraft.
PS my comment is the result of a 32 year flying career including Army Black Hawks, Turbo props, Regional Jets and retiring (at 55) off the 767, so my approach definitely comes from a pilot's mentality more than an engineers. 🍻
It looks like you have several spur gear reductions in a row. Can you say why you didn't go with a simpler high-reduction-ratio system like a compound cycloidal? These are usually more compact, and are used in industrial robots which require very high torque from very compact gearboxes.
That said, I think most RC servos have spur gear reductions as well, and don't use compound cycloidals. Is it a tolerance problem?
Wooow is amizing 😮
Nice design 👌
You could run a mechanical hand crank line from the cockpit to the landing gear locking arm to get it to lock out incase of electrical failure. The gas strut is going to add to the stress of the actuator by a fair margin.
Also gas struts wear over time and are tempermental in different weather circumstances.
Instead of limit switches you should do a Hall Effect sensor on the actuator and use the teeth of the landing gear to determine position. It’d let you show % open and it’d cut to one sensor rather than 2 switches. Less likely to wear over time too.
Magnetic reed switches are fantastic things. The RV-12 uses them for the spar pin warning system, never had a failure. One up, one down, one in the middle if you so desire.
Very cool.
Great video. Can you show some more details on sequencing logic and explain how the landing gear locks are released?
The landing gear locks use a solenoid to trigger their release. The locks have "fully open" and "fully locked" limit switches so that we ensure the lock has cleared before driving the motor. Sequence is: drive the lock solenoid, wait for the lock to "fully open", drive the motor.
Carrying that plane around like it's nothing and hauling around in a uhaul truck hahaha.
Crazy how light it is. Love seeing the progression of this project
Cool ideas here but the complexity of the gear design in both manufacturing and operation would be my concern. Not sure about the carbon leg or gas strut in very cold temps. How does electrical/ mechanical failure of the motors, clutches affect emergency lowering? Seems like the suspension shock/strut is quite heavy. Titanium spring leg would probably be lighter and certainly more reliable plus zero maintenance and likely cheaper to produce.
Recommend you do the gear drop tests at -40 to see how the carbon reacts. There are also known long term effects on CF strength from moisture, temperature and impact exposure within the matrix.
I think they have done amazing work this far. Reading the comments though, I thought I was the only one concerned about the carbon reinforced plastic landing gear. Landing can result in such a variety of shock loads in many environmental conditions. I'm not sure this is the best application for carbon. Bugatti for instance x rays the carbon chassis at specific service intervals to make sure there aren't any stress fractures. Landing seems far more rigorous than what most Bugattis see.
Also the gearbox which is a work of art honestly, while it works well now, I'd be concerned about dirt or moisture affecting the movements, the small diameters on gears seem a little concerning. Given the space constraints, perhaps a worm gear setup would be simpler?
Amazing. You guys are so smart! Have you considered the fact that the gas struts might fail too? Maybe use two, one on each side for redundancy. (older cars with gas strut assisted hood opening mechanisms commonly fail, this is why I ask)
Very cool project, the landing gear design is pretty neat. Would it be an option to incorporate a turboprob engine like a Turbotec TP-R90 in the future? Those modern regenerative turbines are roughly as efficient as piston engines.
Turbines can be pretty good at cruise. They can be pretty bad while sitting on the ramp waiting for a clearance.
@@rnordquest I had not heard of Turbotec until now, but it does sound intriguing and fuel efficient. They are only 130 hp so not super powerful. The intriguing part is fuel burn is 5 gallons per hour and they only weigh 170 lbs and TBO is 3,000 hrs. This is from their website:
“Turbotech designed the regenerative turbine from scratch and it combines all the advantages of a turbine engine with very low fuel consumption. A regenerative turbine is a turbine engine equipped with a heat exchanger, capable of recovering the heat normally wasted in exhaust gases and reinjecting it into the combustion chamber, leading to a dramatic fuel burn reduction.
The idea of using a heat exchanger in turbines is not new, but the real challenge was to apply it to the aviation industry sector and its need for a very light, compact and reliable heat exchanger. Turbotech has managed to develop an exceptionally performant microtube heat exchanger, thanks to 10 years of research & development.”
yeah!
Why did you settle on a compound spur-pass design over a coaxial geartrain like a planetary or harmonic drive? The large exposed spur gear on the main pivot shaft seems risky from a lubrication/contamination perspective. Also, what engineering and environmental factors do you design to on a mechanism like this for an experimental aircraft? I've worked on and designed several mechanisms compliant with NASA STD-5017, curious if there are any equivalent FAA requirements or guidelines you use for things like friction factors, torque margins, or fault tolerance.
So when is the fixed gear version being made? Gas strut for the emergency gear extension? Those things barely work when cold soaked.
How much does CG move back when the gears retract?
They appear lightweight. Probably less than 5% of the maximum weight. Or 1500x0.05 = 75lb. About half of that wt. actually swings aft. It would be like putting 35-40lbs in your baggage area.
Trying to understand why the rear landing gear was engineered to over travel so far passed the natural 90 degrees from horizontal? I worry those shocks may weaken over time and not have the necessary force to push forward to lock the arm in the event of the gear motor failure.
Maybe the intention is if the lock mechanism fails for any reason, won't collapse due to the aircraft weight on landing.
The wheels need to be positioned relative to the Cg of the plane and not an arbitrary 90 degrees from the swivel.
@@mattym8 Well that makes sense. I just fear the wheels not going forward far enough against the drag if the shocks get weak. Maybe they add some type of manuel crank as a back up.
@@rotaryperfection I saw a shaft connected to one of the gearboxes in a few frames. I think this shaft is a manual crank. I agree with you that it's necessary.
The CG shift when the gear retracts is concerning to me. Still, a very cool design all the way around. Well done.
I was thinking of the Cessna mlg retracts at first. Your comment does make me question the cg also as this design has a lot of weight on the strut. It looks really expensive either way.
@@9HighFlyer9 The high wing Cessnas with retractable gear have a fairly wide CG range and tail surfaces large enough (tail volume) to handle the CG shift. The DarkAero bird has (I'm guessing) a fairly narrow CG range but the low mass of the carbon fiber gear may not cause enough of a CG shift to cause problems. I'm sure all of this has been considered by the designers/engineers. 😎
Stepper motor would be nice to set limits and travel speeds. Like slowing it down when it gets close to travel limit or as it’s latching. Then have limit switches also as a back up.
Excellent as always guys, but I’m not quite liking that gas spring idea. I don’t know enough about the entire gear system, but I have built things using gas springs and I know the failure rate of them. Tell more about this spring. Thanks
Yeh l have to agree
I don’t know how significant this will be but my concern with the retracting configuration is that there will be an aft movement in the centre of gravity when the gear is retracted and a forward movement when the gear is lowered. How much movement will there be, and to what extent will this affect longitudinal static stability, pitch control, and stick forces during take off and landing. I assume that during gear up flight you will want the CoG close to the CoP in order to have light stick forces.
I would also be interested to hear more about FAA involvement and certification.
Extension under failure mode: what about a clock spring type solution around the gear pivot point? Does that place too much stress on the motors? Or too much weight?
I really hope you guys build a 4-6 seater as well
Great video. You guys seem to be making great progress. May I ask what make of Hydraulic power pack you were looking at initially?
Thank you! We looked at a couple hydraulic power units, but the one we showed in the video is made by Parker.
It’s interesting - it seems like a super high angle of attach for the gear, especially in a flare. Any comment regarding this?
Thanks as always guys!
The angle that's important is between the trailing link and horizontal, which is probably okay.
All u need is a hand crank and cable for emergency attached a cable and pully to the pivot points and have a hand crank somwhere in the cockpit to use similar to the cessna 310r
Great video , thank you, I say limit switches are prone to failure in addition to the hardware overhead, I would recommend to actually add some sensitive current sensors (its already required) to the DC motor to monitor when it reached its limits, I understand that the aerodynamics force resistance might make it a little bit more difficult to decide on when we reached limits, but I am positive it is very doable.
For reliability I would hope that they do not use mechanical limit switches, but a current-based backup would still be appropriate.
Reed or hall switches could work for this, as they are not subject to contamination.
Can't wait to see it pushed to its limits.
That gear box setup looks similar to the 4wd actuators used on trucks. They are very reliable.
IMO hope you're using brushless motors. Brushes in my electric chainsaw have failed twice. What if something on one gear fails?
Brushes are simple and can be inexpensively replaced, they also take a loooong time to wear out if engineered correctly, my Honda Civic starter lasted nearly 2 decades before the brushes needed replacement.
Thats really cool. Just wondering if you could use load sensing on the motors incase your end of travel switch failed the motor would sense over current and stop driving?
Please make sure the gas spring fill is accessible with sufficient clearance for regular pressure checks using a shock inflation pressure gauge
One question mark the gas strut for emergency extend. They do make custom gas struts for aircraft but it would be expensive. Mfgs don't list prices, only available by quote. Consumer grade struts (pickup tonneau cover) have no quantifiable engineering specs, service life/cycles, etc.
I love how much detail you're willing to show. Impressive design, love to see it!
Cool cool
Only thing with gas spring is it's much less effective when it's cold. Why not use something with a reservoir like a high end nitrogen shock? Works for off-road applications. (It's probably a dumb idea, I know. But maybe it's partially not?)
As I've mentioned before. I've been a aerospace manufacturing engineer for 30 years ( no you tube arm chair warrior here) and I'm just always so impressed with your work, logic and innovations. Pro all the way. You guys work the same way I do, and let me tell ya, its rare. Would love to meet you guys one day. Keep up the fantastic work guys.
Keep it Up guys.
If possible Put non Stick paint on the Outer Surfaces.
Nice engineering! How about exploring an aerodynamic solution to deploy/retract landing gear? Using some of the air pressure from flight to move the landing gear by use of winglets and maybe duct work to generate force where needed to assist the landing gear movement. I obviously haven't calculated what kind of volume of air would be needed, but it might be possible if OK with slower landing gear movement in return for lighter, cheaper solution?
Very Forward thinking. I can't help but wonder about the Gear box integrity over time. Given air loads on cycling.
Good Luck on the project.
I wonder if those gas struts will still output the same force required to lock the gear out through the varying temperature ranges it'll see during regular use
They won't. Almost certainly.
Can you set up to use main gear as a speed brake into a partial extension to come down fast? I would still love to see turbocharging for high density altitudes and high altitude cruise.
ULpower has now a turbo normalised version of the engine used in the darkaero. gives a litlle higher power output but its weight is a little higher too
Are these ever going to go into commercial production? Really cool plane too!
The design is intended to be produced as a kit. More info at: darkaero.com/aircraft
Very similar to an rc retract with a small motor driving the ststem via pinion and gear. On rhose systems i believe its timed to operate a certain number of seconds to complete a cycle.
I wonder using a tension spring to default to its naturally gear down position and use a compact hydraulic actuator power pack like on a Boeing 787 spoiler to push against the sping into the retracted lock position. Emergency deployment would be fairly straightforward by releasing the gear locks using a cable system. BTW, I love your work
G,day Riley, River and Keagen from Sydney Australia. The Dark arrow is looking areospace category.
Landing gear extend
Emergency extension to the down and locked position, (automotive gas struts) they wear out if forced over their design capacity. Example
Rear station wagon door.
Q1. Will the strut motor and gears place pulling force on the gas strut?
💡😎
You can also not install the gas spring and the pilot use load factor to push the gear into the lock position.
Will there be some rubber boot or housing to prevent the gear from kicking up a pebble into those gears?
Great video as always
Up in Michigan the gearwell would be full of sand and snow after a few landings.
Yes! We are working on a cover for the exposed gear segment. Thank you for checking out the video. :)
At 2.11, why is the lower shock mount not in the same plane as the trailing arm, that bushing does not look like it would allow enough flex for the amount of travel, seems as there will be binding. Anyway awesome stuff, good day
Ah ha, Watched it on a bigger screen and now can see that the lower shock mount itself is bushed. If you milled the trailing arm with the lower shock mount in phase with the trailing arm pivot, that would simplify and lower wearable parts count. Anyway congrats, going to look sweet in the air.
good work. to what extent are the cog wheels in the gear box hardened? Did you also consider a worm screw?
You guys have been busy!
Muito boas as soluções que os Senhores apresentaram, na qual parecem simples mas ... parábens !
"Yap yap yap yap". Fly the plane. 😂
Great video! I do have a question: the gear on the landing leg seems quite exposed, will there be some kind of cover? I can imagine that this could get quite dirty (especially on grass fields). Anything in between the landing-leg gear and the gearbox pinion gear (e.g. small stone, other hard debris stuck in grease) would not only disable the electrical retract/extend but potentially also the emergency extend.
If battery and electric engine technology gets lightweight enough would you consider trying to convert this aircraft or make a version of it that uses those systems?
Can we get a tandem tailwheel version? 👀