Testing WWII Era Terrain Following 'Radar' On R/C Plane 

Heres the glider from this video: www.fmshobby.com/products/fms-2300mm-fox-v2-pnp/?ref=RCTestFlight Use code $10RCTF or RCTestFlight to get $10 off

We all agree that you should continue the Solar Plane series!

Those droneless camera birdview shots of the foam plane were top tier lmao

As usual, fantastic film. Re your vortex shedding imagery, I used to be a scientific photographer at the UK’s MoD Royal Aerospace Establishment, not really what you were trying to do, but in wind tunnels we used to use UV mini tufts on models to view localised flow patterns on the surface of the fuselage. Short lengths of thin string, with a UV fluorescent dye on it, at night with a good UV source and a camera with a high frame rate might give you some lovely images. Keep up the great stuff.

It seems like the feedback loop needs to account for both height above the ground and pitch. A pitched down plane nearing the water needs to pull up, but a pitched up plane near the water will soon be high enough above the water without further pulling up. In other words, the altitude adjustment loop needs to know if it is too low and pitched to go lower, or too low and pitched to go higher, with a weaker or even inverse adjustment in the latter case. Likewise for being too high. This was very apparent with the stick based design, but I suspect would be much easier to implement with the flight controller and ultrasonic sensor design.

OMG that vape car hotboxed scene was hilarious! Actually made me laugh so hard. Thanks for that.

You should measure the lag of the sonar sensor. Any lag in the PID "plant" moves the zeros and poles of the transfer function, which affects oscillations and stability

Flight ontrol systems engineer here. Your videos are a delight, but with a bit of frustration around control design. I am sure that if you invested half as much time in beefing up your control systems engineering skills as you spend with 3d printing and whatnot, you'd be much less often puzzling over what's happening and you'd cut on the trial-and-error stage. The hard part is probably the aerodynamics though. Unless you make a wind tunnel, or you invest in CFD software, you'd have to characterize the plant's response in-situ, which is challenging (but since you seem to be able to always have something that at least flies, it might be sufficient). Anyway, hats off to your dedication.

Wingtip vortices are fascinating things. At Oshkosh one year they had a Sea Fury with wingtip smoke being followed by a Mustang down show center. At the end of the runway the Sea Fury would pull up hard and bank to the right...which turned the smoke to a swirling mess behind it that in a couple seconds all came together in a perfectly round smoke ring...that the Mustang would then fly through. I thought this was the neatest thing I'd ever seen.

I'm flyin low checkin efficiency gains Testin wing shapes on RC planes Deep cords feel stronger ground effect buzz But thin ones might get better results This Fox glider got a long wingspan Should feel ground effect above a meter scan Installed sensors, art pilot too Try fly itself at the right altitude Tried followin the surface below But it kept bouncin, just wouldn't flow Tuned the PID but nothin worked right Still oscillatin out of sight Pontoons I added for water tests Flyin on the lake, flyin my best But the controller still had issues Keepin it steady, raisin fizzles Tried flaps next to make it rise higher Near the water, make the altitude wire But they couldn't stop the jumps The pitch and airspeed just too much pumps Wand concept next, canards it did flex Rotatin surfaces based on checks But responses had to be lessened Then it was too weak, flow now questionin Came up short on solutions galore But problems like these I want more Control systems is beyond me ya'll Hit me up if you can help it's not small Learned thick cords feel it most true But efficiency gain scales are tough to accrue Scale affects it heavy too it's clear Big planes don't feel it, only up close and near So ground effect tests will keep rollin on Till self stabilizin designs are fully gone Appreciate y'all watchin my vids Subscribe if you dig it, peace I bid

Great series! In my experiences with PID controllers, sometimes using x*abs(x) on the output can smooth out oscillations. In other words, square the output of the PID, but keep negative values as negatives. This results in exponentially lower sensitivity the closer you get to zero.

@rctestflight I've worked a bit with terrain following systems, and it might help you to aim your transducer more forward instead of straight down. That's generally the biggest flaw that most folks encounter with adverse pitch cycling is that the transducer is looking straight down, which causes the angle to point backwards when the aircraft is in a dive, and causes it to look forwards when it's climbing, and this creates a cyclic failure. However, if you mount the transducer pointing more forward as the aircraft climbs the transducer will not get the necessary feedback, and so it will slowly come back down in pitch which is much more controllable and creates a more expected less chaotic pitch control.

The fog machine in the car. I had a Cheech and Chong flashback moment!

The polite abruptness of "thanks for watching, bye" - is art. Only reason I'm not mad when these videos end.

Great video! As a control engineer, I suggest using MATLAB or similar tools to collect, analyze data and understand how the aircraft behaves. Testing altitude control ideas in the software before trying them out at the lake can help optimize the system. Also, be mindful of potential delay or lag from the sonar system, as ignoring them might cause issues with altitude control. Excited to see your progress!

The Rate in witch you pump out such high quality Videos is just insane!

On hydrofoil sailboats, the wand connects to the foil via two bell cranks and a push rod. The forward bell crank has a screw to adjust the ratio of angle change to pushrod movement (aka the gearing). In heavier seas we up the sensitivity and in flatter water we keep it as low as possible (because any flap movement is increased drag). It would be neat to see a mechanical tuning system for the canard’s instead of just changing their area. Keep up the good work!

The large tall T wing on the purpose built ground effect plane stabilizes it by being further away from the ground effect itself, and losing more lift as the plane climbs, which makes it pitch down slightly. Maybe the same effect would work with a negative stagger tandem wing, or with small fixed canards near the ground.

Something to look at is the airspeed at which the highest efficiency occurs. A simple starting point is stall speed, as this is easily observable. (other measurements will require data collection) Typically ground effect helps lower stall speed, and lowering the speed across the performance curve. Effect feels like flying a lighter aircraft, makes if feel more floaty.

I see one reason for the osillation in the linear actuation of the canards, the controller reaction should be weaker at low and stronger at high altitude. If you want to use a mecanical ground following controller, a possible solution would be to use a crankdisk and connect the controll surface at "top dead center" when the "ground following stick" is at its lowest point, with a second lever at the controllsurface right at 90°. But it would recuire some testing.

As someone who formerly worked in a vape shop in the day of the classic mods. I definitely screwed several together and shoved up to 7 batteries in one stlet of copper tubes before it ignored several batteries and I had to throw it out of the garage door at the shop. It would probably create 1/2 the smoke of your machine only using 4 4680 batteries and a massive 8 coil atomizer with less than .1ohm guitar string colis. It was not in any way vapeble and required an air hose and a cut up 2 liter bottle to funnel air and a bottle of vg to prevent it from overheating immediately and going into flames. I installed the security cameras and my boss was there most of the time so he should have stopped us.

While flying an IS-28B2 Lark sailplane (17 m / 55 feet 9 inch wingspan) on landing approach I was instructed to land long as the gliding operation was moving to the other end of the runway due to the wind direction changing. Fully retracting the air brakes while holding an altitude of about 10 feet and at a speed of 50 miles per hour the glider floated the length of the 2300 foot runway with very gradual speed loss, touching down at about 40 mph with an easy roll out to stop at the end of the runway. That, for me, was a very practical demonstration of ground effect. Thank you for all the analysis of the remarkable phenomenon of ground effect.

Real neat wingtip vortex visualization! I live under the flight path for 12R at KMSP within a mile of the runway. We can often hear airliner vortices interacting with trees on the ground sometimes after a minute or more after the plane has passed. It's really damn cool to hear!

The text: My current project is building a plane which autonomously flies slowly and roughly low so I can run a waypoint mission and ride along with it on my bike, watching that footage of you flying your plane next to that boat got me hooked even more now. I got inspiration for this when watching your STOL multi-element wing plane flying a mission in that park. So yeah, shots of you chasing your builds are the coolest! 12:12: Shots like these are what makes your Videos special

The ground effect on the lower aspect ratio ("deep chord") vehicle is more noticeable because it starts from a lower point in the efficiency scale, the glider is far more efficient with its high aspect ratio wings, so it seems less noticeable but is definitely there, glider pilots need to pay atention to it when landing. For the "terrain folowing canards" to work I would recomend using a thincker symmetrical airfoil (maybe an NACA 0018) and to limit its actuation to a incidence smaller then the stall angle, what is probably killing the idea is the stall od the surface and non linear response on the canards. For the flaps, it is true that lowering then increases lift, but it also increases pitching momment, so it would be necessary to compensate for that. If you want I'll be glad to help, I belive you come very close to getting it to work

You are a goldden god. Being able to fly from a speeding boat in rough water, and all the ground sensor elevator control, golden.

This is the most visually pleasing video you or any rc video…er er er has ever made 👍 following your plane with the boat and reaching out and giving the wing a 👊 was tool cool. It would be very interesting to see more videos following an rc boat plane as it traverses through you experiments and local terrain. Keep the videos coming 👍👍👍

I haven't felt motion sickness from a video till now. Congrats

I think you should connect the giro to the sonar sensor, so you will be able to compensate for the angle change, and almost fully control the plane based on the giro, but adjust the altitude based on filtered and processed sonar data

I love how you add an autopilot to anything that moves. Very skilled.

Always love your engineering mate! Out of all the RC channels, you use the same principles they use to create real aircrafts.

I'm a mechatronic engineer (control systems are part of that). A physical control loop, a digital one and an analog electronic circuit all follow the same rules and are modeled in the same way. In digital you have P, I and D. P reacts directly to the error, I reacts to the cumulative error over time and D reacts to the rate of change of the error. In a simple physical control loop you have a spring (which provides a proportional response to the error), a mass (which has inertia and doesn't want to change speeds), and a damper (which reacts to the rate of change). Your physical control loop has only a proportional response to the error, so it oscillates like any proportional-only control loop. If you want to add I and D to get a working control loop, you should isolate the probe from the control system with a rubber band, have a gear system so that a flywheel spins up in either direction as the error changes (to provide I) and a brake that rubs on the flywheel (to provide D). To providing tuning of I, you'll need a way to change the rotational moment of inertia of the flywheel, by either changing the mass or moving the mass closer to or further from the centre. To provide tuning of D, you'll just need a spring or rubber band that can have the tension increased to push harder on the flywheel. Probably the easiest way to achieve this would be by screwing weights into an electric scooter brake disc (about 75mm diameter) and mounting the disc to a drill's planetary gearbox (backlash in a 3D printed geartrain will not be kind to you). If you want to learn more about this, look into "spring mass damper" systems and state space modelling.

As always, very fascinating concepts and solutions to your hypotheses! Love your videos Daniel...they always inspire me and provoke much thought!

Use forward sweep to get better ground effect by thinner wing chord, this will also Improve the turning ability with less roll. Forward sweep has a similar flow characteristic as ground effect, therefore it will improve speed , lift and weight

Dude! Another awesome video! A++ all the way around. Content, editing, narrative. You’re nailing bro! Thanks for inspiring my inner engineer to play. RC, micro controllers, 3D design & printing. PID. Checking all my favorite boxes. Love it! 👍

One of the best videos so far. Great explanations, education, great footage, and you used so much cool tech: 3D scanner, power bank, lasers, smoke machines, and much more. Very cool. Also hilarious when colin was driving around in a hot boxed car lmao

Wow flying from your boat looked so much fun with that floater :D

Thanks for sharing! Cool what you do! To learn about those wingtip vórtices and the efficiency of ground effect!

You make just such high quality content and explain everything perfectly

Wow what a great channel, so pleased I've found it. Can't wait to see what the next couple of years brings!

As always I leave your videos feeling more motivated to finish my projects and try new ideas. Super interesting video.

I love these technical videos of yours. I cannot tell you how refreshing it is to have a real long form video to watch rather than some clickbait BS.

Oh my dear, i love your experiments, thoughts and your efforts. You should be a teacher, but not in school (is boring) but in a free class for all those children (and adults) who are willing to learn for their life and have fun! Thank you so much for sharing!! 🥰😘

I'm so impressed with the quality of your videos, thank you for making such interesting stuff without getting stuck in gimmick territory.

Daniels channel is the most interesting RU-vid channel there is. I even watch his ads. LOL! Seriously, this channel always is interesting. Even when he was a kid.

Very interesting, love watching the videos, it’s fun hearing the results from your experiments.

Love your videos. They are always educational and fun. Keep up the good work.

9:00 That's not a vape, it's a Füm held next to something else LOL

Cool progress in the ground effect experiments. Those fog shots of tip vortices is really cool.

FMS are making some gorgeous aircraft lately. I've got the Moa 1500mm. Love it to bits!

Such good filming. Good science, too. Thanks for sharing!

This is so interesting! Thanks for sharing your experiments with us.

Fascinating! And i certainly admire your determination!!

This is very cool, don't give up! It reminds me of hydrofoiling sailboats like the Moth that use a "wand" going down to the water to control flaps on the front wing

One thing you could try is making the rods of more flexible material. Even more so you could have them of greatest flexibility at the point and gradually decrease flexibility down the length if the rod. This could be done in part by varying the width of a given material

Double-check the barometer and right around where the barometer hole is. This behavior the fox glider had where it just moves up and down a couple feet randomly sounds like a problem I had where a little tiny piece of tape was being blown into and out of the little bay where the FC was, and it was changing something about how the pressure would change in there, and making the quadcopter bounce up and down a foot at random times.

I love this channel. Always something interesting and I love seeing the scientific process in action. 👌🏼

you cant tie the altitude error directly to the elevator. pitch controls vertical speed, which in turn controls altitude. so the altitude error must be used to generate a vertical speed command, which in turn generates an elevator command. i spent a fair bit of time myself dinking around with altitude control loops for uavs, getting a balance of stability and responsiveness is for sure challenging

I LOVE your videos!! Keep them coming! A Close Coupled Canard may be better for ground effect. IGE pressure under the wing increases which causes an upwash at the leading edge which will increase the lift of the close coupled canard, causing a pitch up away from the "ground". Also a swept wing pitches down less IGE than a straight wing because of less center of pressure shift. In fact 25⁰ to 45⁰ swept wings with a tall OGE T tail will also work!

In the sonar code try adding a smoothing code RNGFND1_WSP_MEDF: Moving Median Filter = 0-255 unless you’re using a custom code in a ardupilot. I think some of the oscillation is the waves Sets the window size for the real-time median filter. When MEDF is greater than 0 the median filter is active

You packed some incredible shots into this video! 💚

the air to air thrown camera shots were great man

The moment u started to throw the camera I scrolled down and tried to sub, yet I've been a sub for ages and u deserve more dude. Creatively your content is unique. Honestly lad keep up the good work, ya made us proud son.

I really enjoy your videos, they are very interesting and informative. Also, the sponsored links and review came in very handy, as I am in the market for a battery backup system for power outages. I will definitely be using your discount code. Thanks!

Magnificently thought provoking yet again. Cool man.

Your smoke setup at night is almost a PIV setup! With the right software you might be able to calculate actual energy in the tip-vortexes and from that perhaps you can say something about efficiency?

As you said at the end scale seems to be the biggest success factor. Go big.

Nice! Also, your initial plane mod (before the prop offset) made it look incredibly photogenic, no wonder the seagulls were envious

Brilliant video, you're so clever and inventive. I'm building a full scale wing in ground effect flying boat. Hoping to experience the effect first hand and learn more about it.

The Kasperwing U/L utilized a single surface airfoil between it's floats, it was very effective in shortening water takeoffs. Ground Effect was also noticeable with the wing between the floats, it might be worth a try on your R/C float plane.

You may wish to notice that PID works well only when there are no other hidden integrators in the system. Integrating twice produces a nice oscillator. Hidden integrators may come in form of inertia of any kind. Things to do about it is either turning off the I component of a regulator, or shifting its frequency window a full order of magnitude away from the existing hidden integrator.

I was laughing hysterically at the vaping/smoke machine in the car combo. Great idea. I would love to see the reaction of a vape store owner when you pull up in front of his shop looking like that.

Speaking as a pilot, I can say that when I went from low-wing aircraft to flying a high-wing Cessna, I definitely made some rough landings at first, because of the reduced strength of the ground effect. When I was learning to fly, getting a good flare was one of the hardest things, exactly because of the ground effect. When the aircraft almost touches down, the efficiency of the wings increases dramatically, which means that even a slight movement of the elevators might pull the nose up too high ("ballooning"), exiting the ground effect again, losing a lot of airspeed and coming down hard.

Mechatronics engineer here! Click read more for some slightly nerdy control advice! I'd love to see this project developed further. Im lead to believe that the oscillation problem may also be a result of the senor range. If the controller always has an accurate height measurement using a range of sensors (like IR and sonar fused with some form of Bayes filter), then the PID gains can be dynamically allocated. An airspeed measurement would also be useful to scale the gains, as the controll authority dramatically increases with airspeed. I like this approach because you don't need a perfect plant model, but you do need a half decent starting guess. A motion model is easy enough to find insitu for the bayes filter, though changing wind speeds/ direction might make for a new headache. So with just height and airspeed measurements, the controller should have enough information to fly without oscillation at any altitude. Pitch sensors may not be needed as sinkrate is arguably more important for stable flight at ANY airspeed. The only other useful information would be the terrain height AHEAD of the aircraft, similar to the terrain warning in real aircraft. this could just be a simple IR senor with a 5-10m range in this case. I think I still have the code to do this from a similar robotics assignment from Uni. Id be happy to dig it out for anyone interested. Loving the ground effect series! I look forwards to your next idea! Thanks for listening to my TEDtalk :)

Awesome video. I love your inquisitiveness and quest for answers. I wondered if the wands that stick down might be touching too far back. But what do I know...not a whole lot.

Definitely more difficult in smaller scale. Nice work.

Never cease to amaze me on how cleaver you are Well done and very enjoyable

In full size aircrafts that are aerodynamically stable one always talk about ”pitch changes speed and throttle changes altitude”, atleast throttle changes vertical speed. Have you tought about connecting the hight measurement to throttle more than to pitch? Might work or might completely fail, might be something to try out as well😊 and as always, great video! Much fun to watch and learn from

I think maybe with the rolls on the water surface it might help to add dwell time to the surface indicated position as you would for temperature or water pressure. Those examples can take time to stabilizes as does the water level with a rolling surface. Up In Smoke has nothing on you and yes the license is on the back of the car.

The mechanical control system on a foiling Moth (similar to the sailboat you showed), relies on what we call a "fast point", where you have maximum control input (rate) at the desired height, with diminishing sensitivity (rate of control surface change for a given unit of wand rotation) the further you get from the desired height. This is key to preventing the porpoising and oscillation you're seeing.

A commercially available gyro would fix all your problems, definitely worth a go, nice work,

Really liked this video. Nicely done!

I really enjoy your experiments! On the topic of water surface skimming vehicles, I'd like to challenge your thinking here a little: perhaps the optimal foils for this application are hydrofoils rather than airfoils. Smaller foils, and the control loop being more naturally stable n simple to control... I suppose that makes it a watercraft not an aircraft, but those are just words. Keep being excellent!

I think that seagulls are the answer to wing aspect ratio and efficiency in flight related questions. Seagulls as of now are a final product of evolution and a time proven BEST construction ever!:)))

I think the camera shots in this video proved that aviation is so beautiful whether it be RC or full scale

I would LOVE to see a build video. I love the behind the scenes-how it works- type videos. Yours would rock. If it's not too much trouble.

The ultra sonic sensor is picking up the wave height difference which is causing isolation. There should be a 2 second sensor delay once level on the water this will cause a less speratic data pickup. Then just adjust elevator sensitivity adjustments and should flow more evenly. The main issue is climate adjustment. To overcome this a larger heavier aircraft will be more efficient since even at a sensitive elevator rate the mass still requires more effort to elevate reducing the amount of oscillation.

The plane with a crutch! What a mad idea!

The shot of the plane next to the boat with the seagull in the background is cool.

To apply the flaps to the controll loop is the right step. You create lift without loosing energy for pitch motion of the entire aircraft. The flaps need to be much bigger though, at least by factor 5! The canards are different, because of their leverage to the centre of gravity and it's coupled feadback loop with two different sets of time constants for the same prameters. The surest way to figure out a stable parameter loop is to keep the number of degres for freadom as los as posible. For instance, for ground effect mode - freeze the pich attitude and work only with flaps and rudder. The pich should be controlled by a gyro, but still keept fixed, when flying in the ground effect mode.

That analogue altitude control worked so well!

I think the sonar sensors would work better if there were more than one on the nose. Or if the airplane's pitch was accurately factored into the feedback loop. If it's nosediving into the ground then it needs to pull way up and fast. If it's just gently descending then it can take its time and think about pulling up. The wands would need a linkage that doesn't yank the stick back every time the ends graze the surface.

Very good testing process!

Thank you for this informative technical video.

After seeing what the plane did with the stick/lever mechanism, I had this thought: apply the stick mechanism to a ‘normally’ shaped ground effect vehicle/plane but instead of thinking of control surfaces for an airplane consider it to be more like pressure control valves. If each side of the vehicle had a few sticks that linked to aileron like ‘vent’ flaps, as that side/area of the wing chord came up to a wave/high spot the stick/lever would open the vent in that area reducing the air pressure in that same area keeping the wing level. It shouldn’t take a very large vent flap to reduce the pressure. The same principle, of multiple small vents along the trailing edge of each side of the wing to reduce pressure, should be able to be applied to an electrical/radar/servo arm mechanism also. Great video as always.

Such a picturesque scene with the plane on the water in the fog!

After watching this fly I have a suggestion. Go back to the canard; this was on the right track. The problem is not the canard, it's the surface following wand. The wand is so stiff it is acting almost like a 2 position switch. As soon as it contacts the water, it's all or nothing deflection of the canard. Rather than using a rigid pole, try using a thin piece of stainless steel fishing wire. The wire should be thin enough to deflect at least 90 Deg with minimal deflection of the canard when force is applied to the tip of the wand. You want the canard to deflect more and more as the wand goes deeper and deeper in the water. It should be at full deflection only when the wand is substantially submerged. To achieve this balance, you may also need to increase tension on the rubber bands you are using to return the canard to a neutral position. By making the wand much more flexible, you are in effect adding mechanical dampening to the system.

The issue is the input from your "sensors" and the output from your plane. Because the input from your "sensors" gets more intense the closer to the ground, and they seem to get way more intense before the plane has time to correct. So being able to adjust the sensitivity, or a delay or something along those lines would be the path forward.

You really need to take some classes in control engineering. Cutting down the canards didn't only reduce the p-gain, it also lowered the saturation limit. A better solution would have been to lower the gear ratio.

Thank you, nice demo! 👍💪✌