Apparently links in the description don't work on RU-vid any more, so don't click on the link below. You'll have to copy and paste it into your browser address bar manually: bit.ly/2X3YXmG
Very nice work. A good exploration of the KFm2 airfoil. I invented this airfoil concept back in 1964 using a paper airplane. It has been a very interesting journey and a big kick to see the concept being used all around the world. ~ Dick Kline
Great Build Chris its funny how the simpler design wings function so well I have a pioneer III plank wing with ailerons and rudder and elevators glides forever keep these videos coming Happy New Years
Takes me back to the days when we used to make control line planes out of pine softdrink cases.......foamboard sort of returning to that era but now nice and light. We would overcome the weight problem those days by having a bigger chunk of aluminium up the front (5cc glow :)) AND 7 strand control lines. Good to see you use lube, similar here only xxxx gold.
I see some nicely engineered flying wing as well as a heavily modified fsi6... Gotta love it lol my first set up was something quite like that... But then I found some good deals on ebay for used taranis x9d plus. Bought it and honestly an improvement we can't put into words. God bless you brother.
Thats a beauty - really smooth. Love wings - yank and bank. My homebuilt wings are finless and I fly them without a gyro and no expo or TX machinations. They waggle a bit on takeoff and during slow flight but at speed are very stable and I dont lose fins on landing or during transport.
I love how you were sure to test the durability first with a precision ramming of the only substantial tree within 1000 miles! Btw, what an amazing place to fly! I need to move!
Would love to see you do a long range video through the hills out there, it's just beautiful landscape with the rolling hills. I don't have that here in Texas ☹️... It's just flat in DFW.
Count your blessings. I live in the midlands in the UK. There is nowhere I can fly legally without paying membership to a club to fly in a small farmers field. 99% of land is privately or local government owned here. Flying in all parks is prohibited with heavy fines possible. I am extremely jealous of the wide open HUGE spaces you have in the USA.
It's very interesting that you are testing this now. I was just thinking the other night about building the Vamp from the old PC game Total Annihilation and was wondering about putting split ailerons on it like the A-10 or B-2.
Isn't he just incredible? I just love your videos as you know, (And I hope someday to move to Australia and live in your shed) but he just absolutely blows me away. Happy New Year Andrew!
Oh the irony all the work that went into previous elaborate airframes that only flew OKish. Enter the cut and shut throwaway and it flys a peach. It was not all waste effort I suspect, by doing multiple scratch builds you have learned a lot along the way especially for some of the off beat designs. +1 for that.
very cool! I'm playing with an rc boat concept that uses a hydrofoil without rudders and instead uses elevons and drag brakes from small rearward wings, basically an underwater version of your setup so far! Thanks! : ) PS Love KFM foils too!
This is an excellent video. I am so interested in drag rudder now. Although I am building a drug rudder airplane, I could get a lot of knowledge in terms of setting up a drug rudder. Thank you.
MMTT or 2M2T Board for Much more than that board, and I think it flies really nice. I can't get that landscape out my mind I swear I see a big earthquake wave frozen into the land. Beautiful land but scarred, wish we had plane finding goats or sheep or something around here. Nice job flying and always love the commentary.
Very nice plane, I like it. The constant nick movement is a typical reaction to a CG that is too far forward. Put it a bit more back and then you need less uptrimm. The up/down wobble will most likely stop and the KFM wing becomes more effective. But you might encounter some tendency to undercut (dive down suddenly with little down elevator). You should bevel the nose of the airfoil on the lower side a bit more, too, to counter that. The rudder function is interesting. But I guess the wing will fly without it also. Since a KFM airfoil gains considerable drag when flying faster, they usually don´t need airbrakes to slow it down. Nose down dives decelerate very quick once the nose is lifted up again. But the reward is a very stable flight wich makes those wings fantastic camera platforms.
Good Lord Chris! Bite off a few MORE advanced concepts at once why don't ya! 🤣🤣🤣 1) Rudder on a delta wing 2) SBUS Mixer - What the #$%K? Did you design some kind of FC with JLCPCB? 3) Ditch the Vertical Stabilizers and get great results 4) What was that Python-looking piece of software with the dependencies and...😖...Geez ...(I'm so lost) 🤣🤣 Can't wait till you explain what you are working on with that "SBUS Mixer" - but that is exactly why your vids are so awesome - you are light years ahead of the viewer and we all are just trying to catch up to that Einsteinian brain of yours, hoping that at some point in the video we understand everything that's going on LOL. You are just amazing man. It's also just way too funny to me cuz I just scratch built a new delta wing (Cuz everybody's flaunting their new AR Wing PRO's) and I was like - "Bill, Just freakin' MAKE one..." So I did, and I'm happy to say I employed techniques I LEARNED FROM YOU (washout, etc) to make it fly nice and slow and fun to fly. It turned out really well. As usual, cant wait to see what's next. Happy New year, Man!!! ✈🚀 PS Almost forgot - CG: With my scratch build wings I find that I'm getting a decent flying aircraft at 18% (which blows me away - because everything I read says 30%) - and I use the flying wing calculators online. Where did yours end up when it was flying nicely? (as a percent)
Yes the SBUS mixer is done by JLCPCB for now. It's more like a generic arduino replacement than a flight controller, although there are a lot of RC specific features. That browser based interface is how you 'program' it. Will be great for people who want to make their own customized stuff without writing source code. The CG is right at the rear edge of the battery, not sure what percent that is. Usually the 25-30% number is a percentage of the mean aerodynamic chord, which for a rectangular wing with no sweep is also x% from the leading edge. For a swept wing it's not so easy to calculate. Placing the CG further forward will also work fine, as you've discovered, but the plane will likely be more nose heavy than necessary.
The acceleration of a hand launch is sensed by the accelerometer as a climb - and then auto-level makes the plane dive. You can sense and detect this acceleration by Pythagoras on the fore-aft and up-down accelerometer axes: this comes to 1g when the plane is just climbing or diving, but 2g or more during the throw. You can use this acceleration value to correct the pitch angle calculated from the accelerometer readings, or (simpler) just detect that a launch is in progress and add a fixed amount of up elevator for a couple of seconds.
I've built one of those kfm wings years ago, they cost nothing to make and they fly like a dream. Once you've flown one, everything else feels over engineered!
hey, you may be able to understand this. if you have a flying wing, you still have two parasitic losses, tip vortex and reflex area. soooo, if you put on tip fences/rudders you cut down the tip vortex. if you then make each rudder into a t tail and make the surface all moving and extend the rudder rearwards enough, you now have full lifting wing (profile). now you can delete all surfaces off the wing to drop hinge drag. and rudder control is done as drag from differential across the t tail on one side or the other
Very impressive little flight test program. A great inspiration! :) Would have been interesting to have seen a camera view looking out and back along a wing (or both) for the various tests. Am curious how control surfaces where reacting with oscillations when fins where attached.
I think you see that the pitch flutter is greater at higher airspeed, which makes complete sense because the amount of deflection you want to achieve a given rotational moment decreases with airspeed. I don't know how much you are able to code it into your FC, but it would be great to factor airspeed into the control. You can get actual airspeed with a pitot tube. You can also model it very crudely with throttle alone or much better with power + rise/descent. I personally am very interested in this.
Hay Chris Happy New Year Mate.....funny you should post this...I keep going back to your Skywalker falcon video and this shape reminds me of the skywalker, Do you think the efficiency is down because of the foil ? "if2d smix controller" Cheers Brett
You can make your own PU foam board if you are so inclined Chris. Might not be as homogeneous, but do-able. Just make a mold and use low expansion gap filling polyurethane foam. Btw, can't kfm be achieved with foam core alone? That's the way I was introduced to it if I recall correctly :) Happy New Year
Sure, I guess it could have been all made with XPS. The foamboard was a convenient 5mm already, and has a tough paper skin, easier to make control surface hinges with. ah, you mean made only with foamboard? Yeah I guess so. The XPS is more rigid and can sand down easier, and only needed one layer instead of another 3-4 layers of foamboard it would have required at this scale. XPS is also way cheaper here. One sheet of 30x20 inch foamboard is about US$5, while a 1200x600x30mm XPS is about US$10. In this particular case, the enormous 2500x1200x75mm sheet only cost me $7. It's possible the store made a mistake pricing it that cheap, but like I say they were trying to get rid of unpopular stock, so perhaps it was correct. Either way I wasn't asking questions :)
Hi Christ, how about performance of this plane compared with your latest Home Sliced ? I meant which plane consume less energy? I really want to know is flying wing better than "non" flying wing in term of energy usage with same speed? Tks
I made a glider over 30 years ago that was just a wing! It was 72", 6" inter, 3" outer with -3 degree, 10 degrees dihedral, and fully symmetrical. I can not remember what chords it had, but the outer was 10 miles slower than the inter. It used flapperons. It was too fast! I used to catch the gliders went they flew over. I could not with this thing. It was made out of pink OwnensCorring insulation.
Nice to see. Looking at your beer, are you in Nelson? I’m in Blenheim. I used to get polystyrene from Expol and hot wire an airfoil for my Jazz/Yagi. Ive just discovered Flite test and built an aircraft based on a paper Freeby. Using the A power pack. Jut ordered some gear to build the Shadow robe and a Prandtl wing, like what NASA were doing. I don’t have any fancy gyro gear. You in the Horten fb group?
Excellent project to take on holiday. Just take a paper template, a hot glue gun, four servos, a receiver, transmitter, motor/esc and a battery. Check in, find some carboard in the nearest rubbish bin and make a plane for the holidays! With a suitable slope you can skip the motor/esc.
I'm using Invensense's 'DMP' which offloads the sensor fusion work onto the MPU6050. Apart from not having to write that code myself, it runs at 200Hz internally while my own main loop can only do 50Hz, and it handles the calibration as well. Somehow it handles the problem of prolonged exposure to non-gravity acceleration without hopelessly losing track of real gravity, but there is a deadband of sorts. For example if I place the board on the corner of an office chair and spin it around quickly, although the reported angle will quickly deviate from the actual angle, the deviation never grows above 4-5 degrees or so. When the spinning stops, it recovers to the real angle over about 10 seconds. So I think that's what we were seeing in the onboard video, except I'm puzzled about why it was more like 10 degrees off rather than 5 degrees off.
@@iforce2d thats pretty cool, i've been using the MPU6050 in some of my projects but haven't looked into the DMP feature that invensense offers. The larger deviation in flight could be due to lower predictability of flight conditions if they have some form of probabilistic state estimator implemented like a kalman filter. I would imagine that, spinning offset in a chair with fairly consistent conditions, the kalman filter would converge to a closer solution than in free flight where there are more deviations and disturbances that feed into the measurments. But that depends on what they actually have implemented, I can't find any good documemtation on DMP that isn't blocked behind an account requirememt. Thanks for the great content!
I could also just be that my spinning chair didn't actually cause as much lateral acceleration as I thought it did, and the plane in flight was about twice as effective at disrupting it. I'll have to try some FPV flights to have a better view during the testing. Yes, I would expect it's probably some kind of Kalman filter.
If it's within the weight and number of servos budget, I think you might get better yaw response if you split the outer control surfaces in half. Use the servos on each wingtip in concert (both up/down) for roll and in opposition (one up and one down) for yaw. That way the inner control surfaces can just be used for pitch control. . Afterthought, actually the outermost control surface on each wing should be just a little bit smaller than the next one in since it would have better "leverage" to affect the plane.
Splitting the surfaces like that was actually my plan for the last year or so while I was daydreaming about it. I might try it sometime but for now this was the quickest way to get something made instead of daydreaming more :)
1:02 ho ho ho I see it imo sweep is what matters most without active stabilizing the control surfaces seem interesting too, would think want largest deflection near tips for pitch
Very interesting.👍 Is the beer your RC TX in disguise? I had an e-conversation with Dr Mark Drela one day about flying wings vs the conventional configuration. What you gain in drag by getting rid of the tail is more or less lost with the detoriation in performance of the reflex airfoil. You need to trim the model by reflexing the airfoil (pitching up the trailing edge) because the CoG must lie ahead of the aerodynamic center (to keep the airplane stable). Nonetheless flying wings are cool.
Flies good for a kfm.....Such a nice simple wing...it's bobbing in pitch....FPV it and it will be easier to adjust the pitch gain...The rudder idea doesn't really work, but an interesting wing...🤔🤔🇬🇧🇬🇧🇬🇧🇬🇧
Unless your'e hung up on caressing sexy airfoils, why spend all that time and effort, when this just seems to work sooo well in every respect. Another really interesting video, thanks Chris.
I've already downloaded the plnas and start making this plane, but what size is the motor, kv and propeller? Huge thank you for all of your work! Happy New year!
@@iforce2d Thank you for your reply, really appreciate it! I don't have such motors in hand but I will try 2826 1400kv with 8 by 6 prop. Hope will be fine.
Seems like yaw incorporated into a wing without vertical stabilizers for rudder installation requires use of elevons which are needed to counter act the roll affects of yaw changes usually brought on by wind. Since you're using your elevons to manipulate yaw they can't also be used for roll manipulation as well?
So the way it's currently setup you can do coordinated turns like in a tail plane? Where you initiate the turn with yaw and counter act with roll. It looked like as you try and yaw left it rolls right, which is opposite of what you'd expect.
@@jamesordwayultralightpilot When the surfaces on the same side split in opposite directions to provide yaw, for now they both move by the same angle. But since they are different distances away from the CG their effect on roll is not neutral. That's what I was talking about at 9:33 and why the surfaces are different sizes. Unfortunately it seems like the inboard surface (which swings downward) is still a bit too large, so to fix this I would need to reduce the travel on those servos. When the auto-level is on, the roll is automatically corrected and we see mostly yaw only 19:36 But yes, you can do coordinated turns. I was having trouble lining it up directly at me because it's so thin I couldn't see which way it was facing.
The issue with launching in auto level is as you throw the plane pitching up, it's trying to pull the nose back down to level. Do you get a pitch down from the elevons as it leaves your hand
hmm.... seems like I might be able to make a special order. Wouldn't be surprised if there is a minimum purchase quantity, but I will look into it anyway.
Hey can u help me its irrelevant to this video i m using inav but my quad has magnetometer problem it detects and calibrate but gets red icon randomly with buzzer beeps tried every setting in config itself but doesn't help , i m using omnibus f4pro v2 exactly u used in ur video with gps neo 8n ublox it has magnetometer inside its an l883 gps seems to work great but not the magnetometer can u help me
@@iforce2d i tried arducopter with omnibus f4 pro but for some reason roll axis horizon is reversed and cat get to fix it any tips and i m using neo8n gps and also it say ekf error something like that and also cant get the magnetometer to calibrate no live calibration options showing up :(
Unless you're using this same system, the settings will not be meaningful. Looking at how it functions as I showed in the video is probably more helpful. This wing glides pretty poorly, I would not recommend for soaring unless you build it very light. It seems like these kfm2 airfoils are mainly best under powered flight.
Where can I read about your "s-bus mixer" it's software and gyro? I want to start playing around with stabilization, flight controllers etc but i don't know where to start. I used to have an Arduino nano and mpu6050 accelerometer i got wii pilot working on it but i accidentally toasted the Arduino before i got to fly with it 😂 Very nice plane! Surprised it works really well too!
@@iforce2d very interested in it myself. You're a clever man. Wish I knew how to use a solder gun as well as you my man. Happy new years from palmerston north
Interesting airfoil there. I didn't know about the kfm stepped designs before now. But I think you have far too blunt (flat) of a leading edge. One of my early scratch built planes had a flat one bc I forgot to sand it round and it had very similar high speed stall behavior as yours. I think that's what happened on your first semi balanced flight test when it suddenly got unstable. At high speeds, the flat leading edge causes major turbulence in the airflow over the wing. A quick change in angle of attack can create a vortex where air rolls back in on itself is n the worst possible spot, after bouncing off the blunt leading edge. This has same effect as ice buildup on full size planes and that vortex tends to self sustain once it's going and is often unrecoverable spin. The original kfm2 has quite a sharp/rounded/aerodynamic leading edge. You should try sanding it to a point or fitting a cover of some type over it so it can allow smooth airflow at all angles of attack. When I did that to mine, the improvement was quite drastic.
@@iforce2d it seems to me like it would reduce the yaw stability by making it subject to the turbulent ram air drag force on the leading edge. Yaw stability doesn't normally result from airstream drag. If it did, I would expect flaps, slats and air brakes to have a huge effect on yaw stability. But, as a lisensed pilot with time logged on most types and sizes of aircraft, I can assure you the effect is minimal, if it exists at all. Your two vertical stabilizers should work quite well to do that anyway. But since you have very turbulent vortexes of chaos spraying off the flat leading edge, it's hard to predict what kind of forces they are dealing with. Imagine a water hose stream being sliced by a sharp knife. You can really control the stream by tilting the knife without much splashing. Now, turn the knife sideways, at right angle to the stream and it's just going to make a big mess and not give much control because it just turns the laminar stream into spray (turbulence). That's what the airflow over your wing looks like I bet. Also, if u sharpen them really well, I bet your speed would almost double. some airbus air brakes work just by flattening the leading edge during landing and let me tell you, they are very effective brakes!
Have you tried flaps, slats, and airbrakes on any planes without a vertical stabilizer though? :) I thought it was a pretty well accepted concept that sweep in a wing is helpful for yaw stability. If the plane yaws one way, the wing on the other side now presents more area to the air stream and therefore higher drag which counters the yaw movement. The more drag the wing has to begin with, should increase this effect. The only reason a flattened knife in a water hose causes splashing is because it's a dense narrow stream surrounded by lighter air, so I don't think that analogy is really applicable. In a larger field of fluid all at the same density, you don't get vortexes of chaos spraying off the leading edge. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-dUhiDctsyfs.html
@@iforce2d I not logged any time on a v.stab-less full-size aircraft because, outside the military, none exist afaik. You're right about the sweep. But, I'm not suggesting anything related to that. I'm saying the thick,flat,blunt-ness of the wings leading edge is the problem, not it's sweep angle. It seems like the very thickest part of your airfoil is the first part the oncoming airstream hits, likely leading to a unclean separation of the flow over/under the wing. I imagine the effect would look similar to the high angle-of-attack disruptions you see on the wind tunnel video you linked. But in your case, I think the flat leading edge could cause that to happen even in straight level flight, depending heavily on the airspeed. Also, while yawing, it's the differential in drag between opposing wings that causes an inherent yaw correction with swept wings. But, I don't see how starting with an increased baseline drag on both wings would increase this effect? it's usually the case that ALL drag has a negative effect on aerodynamic performance and should always be minimised unless your coming in "hot" (too fast) to land, in which case you want to be "dirty" (intentional side slip, gear, flaps, slats, airbrakes deployed) to slow it down. Of course, this is all just my speculation coming from an interest in your project. I don't mean to be critical as you've done a great job here. You make a fair point about my waterhose analogy. When I get some time, maybe Ill try to model it in solidworks and run a fluid dynamics simulation so we can graphically visualize the airflow. I've always wanted to try that.
Links in the description don’t work?? ODD just watched a few others and they had links to Banggood Ali Express and Amazon. Hope all is well with you. Mark.
Yeah for me it is never a direct process where it goes to Google with RU-vid redirect back to the video the back to the RU-vid redirect then on to the next redirection and then possibly to the site or there is another redirect to an app
Try copying this manually into your browser address bar: bit.ly/2X3YXmG I have no fucking idea why RU-vid can't just let us put links in the description any more.
