Dave's Canyon Quadcopter Idea - Page 1
Forum section: electronics / projects

author: EEVblog
author_rank: Unknown
timestamp: August 02, 2011, 11:39:04 am
content: Split off from another thread I didn't mean to hijack.Quote from: RCMR on August 02, 2011, 08:31:54 amThat might actually turn out to be rather desirable?I want the effect of the camera kind of "floating" through the canyon instead of obviously "flying" though with great precision.QuoteYeah, I've seen that. My idea was to just try and eliminate that and make it simpler, because I don't have the same performance requirements as regular quadcopters.I need it to do just one specific task, get one continuous shot through a complex canyon.QuoteYeah, but the devil will be in the detail I'm sure.Canyons are so narrow (several meters to say 30m wide) with a complex terrain that generally drops (via waterfalls), with all sorts of fallen logs and vegetation on the walls etc.No GPS reception at all.I originally thought to just fly a regulator stabilised quadcopter through, but the twisting nature of canyons means you have to "hand-off" control to several people stationed along the way many times as the canyon changes direction and you lose line of sight control. And the complex terrain floor (sometimes with waterfalls you have to jump or abseil, means a single controller following the copter through would not be possible.I'm probably best just experimenting with a regular stabilised video capable quadcopter first (suitably modified for canyon wall impact and water landing protection) and see what problems actually need to be solved first!Anyone got any recommendations for a low-ish cost stable video platform system that could be modified like that?QuoteIt's for "unanticipated" landingsActually the terrain floor could be anything. Water, huge boulder fields, sand, logs etc.QuoteSounds like fun!Dave.

author: Trigger
author_rank: Regular Contributor
timestamp: August 02, 2011, 12:46:23 pm
content: When I was working on UUVs (unmanned underwater vehicles) in the navy we had a similar problem. How does an autonomous vehicle move over unknown bottom contours along a course and not run into anything. We ended up using a high resolution short range sonar system.With an aerial platform weight is an issue so whatever the system is needs to be light and 'good enough' to do the job. Radar would be the typical answer but that's too expensive. I'd try playing with some strategically placed laser rangefinders with an ultrasonic backup for altitude. A small scanning ladar would be ideal but getting it small and light enough will be a problem.

author: RCMR
author_rank: Frequent Contributor
timestamp: August 02, 2011, 07:28:21 pm
content: If I had to solve this problem I'd build *two* quadcopters.One would fly a path above the top of the canyon (where it would have clear GPS and could thus fly a precise path) and the other would fly through the canyon.I'd use a video link from the lower quad to the upper quad and then back to the pilot station. Likewise the RC signal would travel from the pilot station to the upper quad which would relay it to the canyon quad.This way, you could fly FPV (first person view) through the entire canyon without the risk of losing the RC link or the video link necessary for guidance.Also, some prudent use of frequencies would help mitigate the effects of terrain.Dave, I don't know if you've watched this video:it's not canyon flying but not too far off it and shows what can be done with the right gear and skills.

author: Trigger
author_rank: Regular Contributor
timestamp: August 02, 2011, 08:09:56 pm
content: Quote from: RCMR on August 02, 2011, 07:28:21 pmThat would actually be fairly effective. You use one quad copter to relay the control signal and video for the other. The high side would have to be bigger but all it would need to do is keep line of sight with the canyon flier. That saves a lot of money for sensors and lost prototypes testing the autonomous terrain following.There was a presentation at DEFCON last year for a DIY UAV. It would be easy enough to build one that would loiter over and follow the canyon drone.http://youtu.be/Dim2-rEO9j4

author: EEVblog
author_rank: Unknown
timestamp: August 02, 2011, 11:57:49 pm
content: Quote from: RCMR on August 02, 2011, 07:28:21 pmOur sandstone slot canyons in Sydney don't have straight walls and open skies, they often close in above themselves (multiple times curves) like caves.We have major problems using 0.5W UHF walkie talkies in canyons.Maybe some sort of strategic placement of RF repeaters pre-placed throughout the canyon?Dave.

author: Trigger
author_rank: Regular Contributor
timestamp: August 03, 2011, 04:05:02 am
content: Quote from: EEVblog on August 02, 2011, 11:57:49 pmThe problem with too many repeaters is control latency. You have the latency of the video getting to you added to your reaction time plus your control input getting back to the unit. You'll have to test to see how much you can tolerate at the speeds you want to go. A multiple radio mesh network might work, one radio mesh units will likely introduce too much lag.

author: Psi
author_rank: Super Contributor
timestamp: August 03, 2011, 04:16:18 am
content: Just a FYI, in case anyone is pondering buying a Parrot ARDrone, be aware that they had/have some code bugs where they ignore control input and fly up up and away (never to return once they catch the wind).Had a friend who lost his ARDrone this way. It's apparently an issue with them that's more common than they will admit.

author: EEVblog
author_rank: Unknown
timestamp: August 03, 2011, 05:44:04 am
content: Quote from: Trigger on August 03, 2011, 04:05:02 amSpeeds would be very slow, almost walking pace.Ideally I'd use one of those RC helium blimps!But the logistics of lifting a suitable camera is just a tad too high.Dave.

author: Unknown
author_rank: Unknown
timestamp: August 03, 2011, 06:01:04 am
content: Quote from: EEVblog on August 02, 2011, 11:57:49 pmIf you can clamber all over the place surveying and installing RF repeaters then wouldn't you takeyour photos/video while doing that? Why the quadcopter other than the challenge?

author: EEVblog
author_rank: Unknown
timestamp: August 03, 2011, 06:25:15 am
content: Quote from: Uncle Vernon on August 03, 2011, 06:01:04 amA mate and I had the idea one day while in a canyon doing photography and some video:"Wouldn't it be cool to get one continuous video shot flying through the canyon?"Sure, you can hand carry a video camera through the canyon, but it's just wouldn't be the same.To our knowledge no one in the world has ever done it. Very occasionally you'll get a pro film crew in for a doco or something and fly a camera along an installed guideline or something, but it's only one part of the canyon.So yeah, it's the challenge of it, because we can...So anyone got any ideas on what the best platform to start with would be?Given the tight nature of the canyon and obstacles, I'd imagine an enclosed rotor (like on the Parrot AR Drone) would be essential to prevent accidental bumps against the walls or rock or logs etc to not crash the thing.Dave.

author: IanB
author_rank: Super Contributor
timestamp: August 03, 2011, 06:55:03 am
content: I think I would try to rig up some kind of dirigible. You would get longer flying time, greater resilience against crashing and a simpler control and navigation problem as you wouldn't be worrying so much about keeping the aircraft stable and level.

author: EEVblog
author_rank: Unknown
timestamp: August 03, 2011, 07:18:47 am
content: Quote from: IanB on August 03, 2011, 06:55:03 amThat was my first thought, but I calculated, IIRC, you would need roughly a 600mm dia helium balloon to lift 100g.Dave.

author: Trigger
author_rank: Regular Contributor
timestamp: August 03, 2011, 01:08:58 pm
content: Quote from: EEVblog on August 03, 2011, 07:18:47 amNot to mention how much wind would affect it's control. It was also my first thought but they have to be rather large to be a practical platform.The relay system would be the most practical to build. The biggest difficulty would be creating the TCP/IP based control system that would tolerate routing and roaming among access points.

author: KuchateK
author_rank: Regular Contributor
timestamp: August 03, 2011, 03:38:40 pm
content: Quote from: Trigger on August 03, 2011, 01:08:58 pmI've built WiFi networks in very large multi-room warehouses (with thick concrete and sheet metal walls, plenty of signal loss and interferences from neighborhood networks). You can have bunch of access points in the area and clients will jump between them as you move without any big issues (single packets are lost during jump). It is very seamless for the clients. Even though people told that simple won't work, no other fancier methods offered such reliability during testing.I've also worked with city wide WiFi. We decided to drop "repeaters" around. One AP was used as client with highly directional antenna to the base and another provided coverage for the area.Considering UAV based on Paparazzi (linux on beagle board) that would have power to handle TCP/IP and WiFi it should be pretty cheap and easy to build mesh network for large area. Old equipment can be acquired for free (B should be plenty) and it is very easy to get good antennas for it. And you can connect each AP directly to base station to minimize lag.Another idea is to get balloon mentioned earlier or second UAV. It can be sent way up and work as a base station/repeater for much larger area. It can also move together above UAV invisible directly for the operator. If you want to fly below something use local repeater.

author: KuchateK
author_rank: Regular Contributor
timestamp: August 03, 2011, 03:58:09 pm
content: Quote from: EEVblog on August 03, 2011, 07:18:47 amLift goes up much faster than the size of balloon. Going from 2 ft. (~60cm) to 4 ft. (120cm) doubles the diameter, but lift is multiplied almost by 10.Check the table here:http://www.chem.hawaii.edu/uham/lift.html

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: August 03, 2011, 04:06:39 pm
content: Quote from: EEVblog on August 03, 2011, 06:25:15 amIf you can pull it off, and get good quality video, I'd imagine the footage (and making-of) would probably have enough commercial value to at least pay for the gear.Slow definitely feels like the way to go, as it gives you time to react, and reduces constraints on live video bandwidth. Also makes for a wider range of possible playback speeds if you acquire a shitload of frames, and probably makes post-production stabilisation more possible.Helium (or helium asisted) may be a good way to go if you have the width clearance for it, as you save a ton of power for the lifting - assuming wind isn't too much of a problem.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: August 03, 2011, 04:11:28 pm
content: Quote from: EEVblog on August 03, 2011, 07:18:47 amRemember balloons don't need to be spherical. I'd imagine a sausage or blimp shape may give you a better aspect ratio for flying a canyon.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: August 03, 2011, 04:17:57 pm
content: Quote from: mikeselectricstuff on August 03, 2011, 04:11:28 pmRemember balloons don't need to be spherical. I'd imagine a sausage or blimp shape may give you a better aspect ratio for flying a canyon.QuoteFor control you could go way lower in frequency, and with a bimp you'd have plenty of length for an antenna.

author: ejeffrey
author_rank: Super Contributor
timestamp: August 03, 2011, 06:40:52 pm
content: For control maybe, but if you are flying this think RC, don't you need a video feed?

author: EEVblog
author_rank: Unknown
timestamp: August 04, 2011, 01:46:00 am
content: Quote from: ejeffrey on August 03, 2011, 06:40:52 pmyes, I'll need a live FPV video feed to control it, as the canyons twist and turn.With the blimp, it doesn't matter the shape, it's the fact that you have to lift X weight, and you have to transport and inflate on site in remote locations.Winds can be a problem in some canyons.Dave.

author: EEVblog
author_rank: Unknown
timestamp: August 04, 2011, 01:53:46 am
content: Quote from: KuchateK on August 03, 2011, 03:58:09 pmBased on these practical one you can buy:http://www.southernballoonworks.com/rc-blimps/remote-control-blimps.html?gclid=CKuC5cXDtKoCFYIlpAodAkij5AA 2.4m long helium RC blimp can only lift 170g!Dave.

author: KuchateK
author_rank: Regular Contributor
timestamp: August 04, 2011, 02:51:05 am
content: Quote from: EEVblog on August 04, 2011, 01:53:46 amThis might be the bad example. They are probably made from heavy material to last transportation between events and technical skills of marketing department6ft. (1.8m) weather balloon weights 600 grams and has nominal lift of 3.8 lbs (1.7kg) and maximum of 12 lbs (5.4kg).10ft. (3.0m) weather balloon weights 1.2kg, nominal lift 7.6 lbs (3.4kg) and maximum 15 lbs (6.8kg).They want weather balloons to ascent rather fast (several hundred meters per minute), so nominal lift is probably specified for that.http://www.amazon.com/10ft-dia-Professional-Weather-Balloon/dp/B00513FWQI/ref=pd_sim_sbs_hi_1http://www.amazon.com/dia-Professional-Weather-Balloon/dp/B004RK2RAUConsidering that 6 ft. balloon is 1.4 cubic meters (50 cubic ft.) and 10 ft. twice that (2.8 m^3) then those blimps that you showed must be very heavy. With 2.6 m^3 of gas they only lift 170 grams and with 3 m^3 a little over 300g.

author: RCMR
author_rank: Frequent Contributor
timestamp: August 04, 2011, 04:37:53 am
content: For the controller I'd be tempted to use the OpenPilot solution (seehttp://www.openpilot.org/).The hardware and software is opensource and it's doing a brilliant job.Here's a video I posted the other day showing the OpenPilot controller in action:As for the platform itself, these are a piece of cake to build from scratch. I'll be posting a "quadcopter build" video in the next week or so, showing the whole design/build process and how the OpenPilot board is installed and configured.

author: EEVblog
author_rank: Unknown
timestamp: August 04, 2011, 05:12:01 am
content: Thanks, didn't know about that one, will check it out.I was going to go with the ArduCopter, as it seems to have the most support out there?Dave.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: August 04, 2011, 09:04:27 am
content: Quote from: ejeffrey on August 03, 2011, 06:40:52 pmYes, but if it's a slow-moving blimp, you don't need high framerates - a medium-res monochrome feed at, say, 10fps with compression wouldn't need much bandwidth - certainly doable over VHF.

author: Trigger
author_rank: Regular Contributor
timestamp: August 04, 2011, 03:32:16 pm
content: Quote from: EEVblog on August 04, 2011, 05:12:01 amIf you're going the remote control route that'll be perfect.I'd be interested to try one of those PIC32 Arduino compatible boards. You could strap your flying pig to it

author: philbx1
author_rank: Regular Contributor
timestamp: August 08, 2011, 09:40:01 am
content: Now this is an interesting subject which I've thought about for a while now.What if the balloon wasn't spherical but more a foldable 'flat-pack'?Maybe we could come up with a low profile balloon to solve the problem ofside winds, although I guess there are not many air currents (especially in canyons)which are predominately on the horizontal plane.That pretty much discounts my idea. Maybe I'm wrong...

author: EEVblog
author_rank: Unknown
timestamp: August 08, 2011, 12:38:17 pm
content: I'm pretty sure the blimp idea won't work.Apart from the size required to lift a decent camera(s) + control gear, the winds (draft?) can be all over the shop due to the dynamic twisting and turning nature of the canyon.Often it is just dead still, but if the winds do pick up, then forget it. Especially at the end of the canyon where it may open into a valley, it can get very windy there.Dave.

author: djsb
author_rank: Super Contributor
timestamp: August 13, 2011, 09:46:04 am
content: Pity you can't just fly a camera equipped bird through the canyon, at least as a first step (do you know of any hawk/falcon handlers-Or a friendly wildlife cameraperson). Then you'd have some idea of what to expect. I know, the whole challenge is in building a contraption and flying it through under your own control. Camera's that fit on birds are surely light enough!Just a thought.David.P.S Take a look at this

author: Jimmy
author_rank: Regular Contributor
timestamp: August 23, 2011, 10:25:18 pm
content: Why limit yourself to 4 rotors?http://shrediquette.blogspot.com/p/shrediquette-mm6.html

author: RCMR
author_rank: Frequent Contributor
timestamp: August 23, 2011, 11:17:54 pm
content: Quote from: Jimmy on August 23, 2011, 10:25:18 pmWhy limit yourself to six rotors?

author: EEVblog
author_rank: Unknown
timestamp: August 24, 2011, 12:09:50 am
content: I've seen 6 rotors carry a DSLR, so that's good enough for me!Is 8 rotors potentially more stable than 6 rotors I wonder?Dave.

author: kaptain_zero
author_rank: Regular Contributor
timestamp: August 24, 2011, 01:32:29 am
content: Here's a video of a 6 motor unit running with 5 props.... seems it's capable of good stability!http://www.rcmovie.de/video/6773c9932fa54a952bb5/Q4-Y6-500-Testflug-mit-5-Props-statt-6

author: shadowless
author_rank: Regular Contributor
timestamp: August 24, 2011, 03:39:32 am
content: Flight time will you the main issue. How long do you plan to fly it? Lipo powered? Check out eagletree for FPV ideas.U can consider a small gilder to take advantage of thermal.

author: EEVblog
author_rank: Unknown
timestamp: August 24, 2011, 04:05:16 am
content: Quote from: shadowless on August 24, 2011, 03:39:32 amCanyons slots are typically a few hundred meters long at best, so only a few minutes flight time are needed for one stretch, maybe 10min tops.A bigger worry will be the remote area and recharging within the canyon.[quoteU can consider a small gilder to take advantage of thermal.Might be a tad hard to navigate a glider through a canyon slot a few meters wide that twists and turns. Our slot canyons ain't like the Grand Canyon!Dave.

author: ivan747
author_rank: Super Contributor
timestamp: August 26, 2011, 02:21:35 am
content: If you want to control the speed on every single motor, maybe lowering the RPM on certain motors is better than increasing it on the opposite motor. If a motor halts, this control will halt the motor on the oposite sidde, effectively balancing the copter. If there is more weight in the bottom of the copter, there's a good chance it will just descent rapidly to the ground, but in a stable way and with the floats down and all the equipment in place.Ivan

author: kaptain_zero
author_rank: Regular Contributor
timestamp: August 26, 2011, 03:08:51 am
content: Run one quad copter as the repeater, fpv style, keeping view of the canyon. Second FPV quad copter can now be controlled via the repeater in the first quad copter and fly up and down the canyon as required. Better yet, a flying wing powered glider (compact size) would be able to circle around, using much less energy, while still being able to carry the repeater payload. FPV on the repeater may not be necessary, it only needs to be "line of sight" with the quad in the canyon, distance isn't a big issue in such a case. Quads fly great, but they are power hungry.If you're planning on charging batteries.... bring lots of big solar cells, or be prepared to lug a gasoline powered generator around. Then again, more battery packs might just be lighter, easier and cheaper!Plan B: Why not find a different hobby? I hear electronics engineering is fun, if you do a video blog about it?!?!RegardsKaptain "Tongue firmly in cheek" Zero

author: EEVblog
author_rank: Unknown
timestamp: August 26, 2011, 05:58:49 am
content: Quote from: kaptain_zero on August 26, 2011, 03:08:51 amOur slot canyons are sometimes only several meters wide, and up to 50m or so tall, and often close in like a cave. So I doubt a repeater above would work, even if it was spot on above.We have trouble using 0.5W UHF walkie talkies from the top of the slot to the bottom.Dave.

author: Nerobro
author_rank: Contributor
timestamp: October 26, 2011, 06:24:27 am
content: To bring some discussion off of twitter.Frist, Dave, good on actually getting the airframe in. :-) I can't wait to see what you do with it.Second, lets discuss N-rotor versus penny farthing or even coaxial helicopters. I'm just going to call them quad rotors instead of N-rotors for now. The only reason for more rotors is for more power, and if you've got good software, you might even see redundancy.Here's how I see it. Quad rotors were made because, more or less, they could. The concept was tried at the start of the helicopters development, and discarded. It was even revisited again in the 60's and discarded. (http://en.wikipedia.org/wiki/Piasecki_PA-97)I am going to start with what I see as advantages with Quad Rotors. First, quad rotors have only four moving parts. They usually have brushless so your prop is directly attached to the outrunner frame. They have no pivot points. They are pretty simple. A frame could be as simple as two paint stirrers.I see simple as good. Very good. But simple to control, I think trumps that. We'll get back to thatNow quadrotors are completely unflyable. At least by people. They are utterly dependent on a multi axis gyro, and a fast acting microprocessor to stay in flight. The "stability" comes entirely from the fact you've got a microprocessor or four going nutty trying to keep the thing airbore. In todays electronic world, it's not a crippling thing. But you also are completely out of luck if anything goes wrong. I know of a couple people who have issues with the outrunner style motors losing sync. When a brushless motor unstarts, the CPU doesn't know about it. Then the helicopter crashes.Okey, so we know we have mostly reliable electronics. And sensored motors fixes the unstart issues. Woo! What about the airframe itself, and power-train choices. To talk about that we'll need to discuss the comparison between the aircraft.A quadrotor has four, high speed propellers. This is not a very efficient method of moving air. You've got tiny little wings, moving very quickly. Each propeller tip making it's own little wake and wasting energy. Shorter propellers have more losses due to vorticies, and I can't imagine the interaction between the propellers does it any good either. The "thump thump thump" you hear from a real helicopter is the interaction between the rotor wash and the tail rotor wash!With a quad rotor, you're blowing on the frame with every propeller. And you've got the frame up close behind the rotor, which doesn't help the aerodynamics of the blade itself. Also the motors are fairly large, causing large dead space at the center of each rotor. (it's the least effective part of the prop, but it's worth mentioning) You also need to consider the downwash of the whole plane is going to interact with the chassis in the middle. As you can see with the dyson air multipliers, the effects of airflow aren't very well constrained to the path of the prop. You've got the huge, unfaired, chassis in the way of your downwash.So that's a problem that can be taken care of with horsepower. Horsepower means bigger motors, bigger batteries, bigger speed controls. Big horsepower means fast response too. ;-) So there are some upsides to flying with the "big stick" method.A penny farthing (read: conventional) helicopter, while still a brutal machine, is much less a "club the air into submission" vehicle. Now, the rotor head of a helicopter is pretty complex. At minimum you need hinges on the blades, and a way of controlling pitch and roll. You'll also want collective. (provided you want the full aerobatic capabilities of a quadrotor...) Which is a third servo.Now, here's a video from six years ago:That was state of the art then. That heli would carry anything you'd ask it to. And there are lots of electric models that are just as capable now. The advantage i see with using servos, is that they self recover, and require little power to operate. While a quadrotor needs lots of surge power available to make it's rotor speed adjustments. Servos also tend to fail in a progressive manner. They start to glitch long before they completely fail. The heli will still fly with glitching servos! (this is experience talking *grins*)So the helicopter can be flown by a human, with human response times. And can fly in amazing directions, I'll even venture to say it's agile enough to keep up with those silly princeton quadrotors. Because they're somewhat stable they also make decent camera platforms. Even without computers handling everything.Conventional helicopters are also available in a wide range of sizes to accommodate almost any payload. Way back when, it was common for film crews to have a man on call with a .90 size heli so they could fly cameras into unusual places. If you watch old tv shows on special effects, you'll see someone with a r/c heli.http://www.diyphotography.net/introduction-to-radio-controlled-helicopter-aerial-photographyhere's a fairly recent article on the subject. Evidently an eflite 400 is capable of carrying a significant camera aloft. (I own an eflite MCX, a Novus FP, and some larger 280 sized chinese heli)Conventional helicopters also only have two rotors to mess about with. The main rotor has long blades with high aspect ratios providing smaller tip vorticies. You also have only one big motor to power, which means a savings in speed control weight. On most medium to large helicopters the tail rotor is powered off the main rotor, meaning that the tail rotor cant' lose control so long as the gearbox stays intact.The bodies on conventional helicopters are narrow, and usually have a fairing, providing an aerodynamic advantage over quadrotors. The tails are frequently smaller than the support struts on a quadrotor, and are tubular, so should have less drag as well. This means you can carry a greater payload, and use a smaller powerplant to do it. Also it means a given battery will take you further.I suppose I could have taken this rant down to "well in the 80's they did it with conventional helis, the quadrotors are a new thing" and been done with it. :-)I will say, quadrotors are neat.Now, for flying down a canyon, I think a single rotor has a big advantage. You only need one frame to protect the rotor from the canyon walls, and typically the rotor blades are hinged, so brushing against something may not be a critical failure. (I do that with my helis all the time...)I can't wait to see how your project turns out dave!

author: sonicj
author_rank: Frequent Contributor
timestamp: October 26, 2011, 07:04:21 am
content: have you seen the stuff put out by trappy & team blacksheep? high speed, long range, low altitude, HD, fun stuff.*edit - doh! RCMR already posted this one on the first page. anywho, heres hisvimeo channel.another guy you might be interested in checking out ispeter glukhov, aka fmkit. he does long range, dare devil type fpv with hacked up wii controllers and cheap FRS radios.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: October 26, 2011, 08:21:09 am
content: I don't know much about the aerodynamic stuff but it seems to me that a potential advantage of a quad is that all your motors are actually providing power, whearas on a conventional heli some are just actuators not contributing to lift. I can see that having to use high speed has issues, as well as having to use a wide range of speeds means the motors & props will often be operating outside their optimal speed range. I wonder if there is any mileage in a quad with 2 big and 2 small motors, the big ones for thrust and the small for stabilisation - the different time constants may be fun to compensate for though...I think the main reason that quads are popular is that the lack of moving parts makes them cheap to make in smaller quantities due to much fewer parts to tool up for. Not to mention they look unusual and hence inherently cool.For a video platform it seems to me that a platfom which is inherently stable is better than one that is dynamically stabilised, as the latter has to move in order for the gyro to detect the movement and correct it.

author: sonicj
author_rank: Frequent Contributor
timestamp: October 26, 2011, 10:32:03 am
content: Quote from: mikeselectricstuff on October 26, 2011, 08:21:09 amthe servos pull very little current when compared to the main motor. for instance, the servos on my 450 pull around .5A each at full load while my main motor pulls around 14 amps at hover and can pull as high as 45 or so under full load. there are efficiency differences between the motors in the servos vs the large BL motors, but with the servo consumption being so comparatively low, wouldn't let that be the deciding factor in airframe choice.Quote from: mikeselectricstuff on October 26, 2011, 08:21:09 amlookup thesikorsky x2. fastest helicopter on the planet. coaxial rotors for lift, prop driven thrust. biggest leap in heli technology in like 50 years.Quote from: mikeselectricstuff on October 26, 2011, 08:21:09 amits not really a cost thing... 450 heli's are cheap! (well.. some, not all) personally, i think the popularity is due to the instant gratification factor. its MUCH easier/faster to get in the air with a quad than it is with a CCPM helicopter. setup and maintenance is alot easier as well. CCPM has a very steep (expensive) learning curve. the quads are cool looking!Quote from: mikeselectricstuff on October 26, 2011, 08:21:09 amthey are pretty much the same in this regard. with the traditional helicopter, the tail rotor pitch is mechanically trimmed to counteract the torque in the direction of rotation of the main blades. a gyro is used to sense drift and compensate via the tail servo. on a quadcopter, a yaw gyro is also required to keep the heli in a heading hold orientation but instead of adjusting a servo, the computer changes the pulse width to the motors.(except for some tri-copters. shrediquette for example) both are VERY fast and imperceivable if properly setup. the quads do have a gyroscopic advantage with the counter rotating blades.both will suffer from vibration issues if rotating parts are not precisely balanced.-sj

author: Nerobro
author_rank: Contributor
timestamp: October 27, 2011, 02:57:01 am
content: Coaxials and quadrotors have an advantage over single rotor craft. As your airspeed goes up, you start having "leading/retreating" blade issues. The blade going forward has higher airspeed, the retreating is lower.A rigid hub coaxial solves the issue handily. quadrotors are by definition rigid hub.

author: sonicj
author_rank: Frequent Contributor
timestamp: October 27, 2011, 06:53:35 am
content: Quote from: Nerobro on October 27, 2011, 02:57:01 amthe phenomenon is called dissymmetry of lift. rc helicopters have dampers in the head block to help compensate. the effect is tunable by changing the damper material &/or durometer. blade flex is another tunable parameter that affects dissymmetry. also, this is purpose for leaving the blades slightly loose in the grips; the blades are free to lead/lag as needed.a well tuned heli should experience no noticeable ill effects of dissymmetry of lift.-sj

author: Nerobro
author_rank: Contributor
timestamp: October 27, 2011, 07:09:02 pm
content: For any reasonable airspeed that is. :-) And we can define reasonable as less than 100mph.

author: EEVblog
author_rank: Unknown
timestamp: October 27, 2011, 09:34:56 pm
content: Quote from: Nerobro on October 27, 2011, 07:09:02 pmWe only need 5kmh or so :->Dave.

author: Nerobro
author_rank: Contributor
timestamp: October 27, 2011, 10:09:55 pm
content: So dave, what electronics package are you using? What airframe?I am going to try to measure the lift capability of my helis tonight.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: October 27, 2011, 11:58:21 pm
content: Something else that may be worth considering - if you were to record all the gyro/acceleromoeter data alongside the video (maybe use the audio track), this data could be helpful in correcting any motion semi-automatically in post-production.

author: sonicj
author_rank: Frequent Contributor
timestamp: October 28, 2011, 01:58:33 am
content: Quote from: Nerobro on October 27, 2011, 07:09:02 pmindeed. i actually had a comment about VNE (velocity never exceed) typed out, but deleted it prior to posting for the sake of simplicity. so yea... don't fly too fast in a helicopter.-sj

author: Zad
author_rank: Super Contributor
timestamp: October 28, 2011, 03:16:17 am
content: Does the multi-rotor benefit from translational lift? I would imagine those helis with shrouded rotors don't, and will have to work harder. With conventional rotors, any forwards motion considerably reduces the engine power needed. Using a separate propeller for thrust or anti-torque is nothing new. The Rotodyne had 2 conventional turboprop engines and vented compressed air through rotor tips.As usual with our government funded research, a lack of money killed it when it was 95% of the way there.

author: Nerobro
author_rank: Contributor
timestamp: October 28, 2011, 05:39:47 am
content: Yes, all powered lift devices have a problem with reingesting their own rotorwash. Or jetwash, as the case may be. Moving (in any given direction) gets you out of your own wash. And it will help quad rotors as well.Shrouds do the whole multiplication effect, but hurt when you're trying to go forward.

author: Zad
author_rank: Super Contributor
timestamp: October 28, 2011, 04:02:38 pm
content: This is known as Vortex Ring, and is a problem with full sized helicopters as well as models. It manifests itself in urban man made "canyons" as well as natural ones. Basically what happens is that the rotor downwash circulates out, up the canyon wall, and then back down again. This downward moving air obviously reduces the effective lift available, and has the result of pushing the aircraft down and into the canyon wall. In most instances the "canyon" is a building wall on just one side, but the effect is the same, and just as expensive.It can also manifest itself if the helicopter is in hover or descending vertically, where a toroid of air movement is created around the rotor disc, sucking the helicopter downwards.http://en.wikipedia.org/wiki/Vortex_ring_stateNote the comment on tandem rotor helicopters. Quad etc rotor machines cannot slide out of vortex ring, and it could potentially be a big problem if not identified early enough.

author: Nerobro
author_rank: Contributor
timestamp: October 31, 2011, 05:23:20 pm
content: Not directly related, other than I'm going to put a camera on it... But here's what I've been working on this weekend:

author: sonicj
author_rank: Frequent Contributor
timestamp: October 31, 2011, 11:52:31 pm
content: balsa? thats retro!i crash too much to fly something made out of wood... is it a kit or scratch build? AP camera or FPV?-sj

author: Psi
author_rank: Super Contributor
timestamp: November 02, 2011, 02:02:58 am
content: Forget camera + FPVdo this

author: sonicj
author_rank: Frequent Contributor
timestamp: November 02, 2011, 04:51:33 am
content: Quote from: Psi on November 02, 2011, 02:02:58 amim surprised the thing got airborne with those heavy steel balls on board.did you see his seatbelt? lol!no d**n way i'd get on that thing and fly around, but i would probably fly this after many hours of sim time.

author: EEVblog
author_rank: Unknown
timestamp: November 09, 2011, 05:38:45 am
content: Looking to get a suitable low cost radio controller for the ArduCopter, any suggestions? (and available in Oz if possible)Plus recommended big 3 cell battery and charger?And what do people do about re-charging in the field?Thanks.Dave.

author: Joker94
author_rank: Contributor
timestamp: November 09, 2011, 10:06:34 am
content: For a transmitter I would recommend Spektrum. They have a cheap 6 channel radio (dx6i) for about $200 Australian from your local hobby shop. They will have all the mixing function that you need, it is easy to use, good bang for your buck and a quality product that you can trust the quadcopter with. (depending on how many rc people are on this forum it could turn into a similar argument as PIC or AVR only with Specktrum/ JR, Futaba or Hitec.)Well for charging out at the feild I have a charger that can plug straight into a 12v lead acid.(mine is a smaller one not a car battery). Almost all rc 'smart chargers' will have the 12v battery supply option, for many cheaper ones this is the only option. I myself like the thunder power charger my particular model being this onehttp://thunderpowerrc.com/html/TP610CACDC.html. all the options you need for any type of bettery.(i chose this one so i know i can trust it when i charger my larger gas models.) Hobby king also sell battery chargers for a lot cheaper and still do the job fine.For batteries Hobby king is as good a place as any, brands such as Turnigy, turnigy nano-tech and Rhino are all good brands and widely used. The major advantage of buying from a place such as hobby king is the price. For a large 3 cell battery(i assume lipo) the prices can be less than half that as a local hobby shop.CheersJoker94

author: Psi
author_rank: Super Contributor
timestamp: November 09, 2011, 10:37:36 am
content: It's not local but i've heard thathttp://hobbyking.comhave really good and well priced RC stuff.

author: firewalker
author_rank: Super Contributor
timestamp: November 09, 2011, 11:23:07 am
content: Quote from: EEVblog on November 09, 2011, 05:38:45 amAs for the charging. A friend of mine has a remote control toy-boat with Li-io batteries. He bought a Lead-acid 12v battery and a small solar panel. He charges the battery at home and hooks it on the solar panel charger a the field. Can't say though that the solar panel will make any big difference for short time usage.Something like that:Or something like...Alexander.

author: Flavour Flave
author_rank: Regular Contributor
timestamp: November 09, 2011, 01:40:18 pm
content: Quote from: EEVblog on November 09, 2011, 05:38:45 amYou should check this radio out. Cheap, loads of channels.http://www.hobbyking.com/hobbyking/store/%5F%5F8992%5F%5FTurnigy%5F9X%5F9Ch%5FTransmitter%5Fw%5FModule%5F8ch%5FReceiver%5FMode%5F2%5Fv2%5FFirmware%5F.html?gclid=COm1k6rQqawCFUtC4QodVg2A7AReview done by Bruce of RCmodelreviews. Posts on this forum as RCMR.

author: kaptain_zero
author_rank: Regular Contributor
timestamp: November 10, 2011, 03:24:19 am
content: For the record, HobbyKing does have an AUS warehouse. They stock plenty of Turnigy Lipo packs, chargers and the Turnigy 9x radio... The 9x is a nice, cheap radio.... I have three but I've been installing FrSky hack modules in them as I prefer FrSky receivers and of course I've switched to custom firmware etc. etc. Dave, I'm sure you are aware of Bruce's site... as in RCMODELREVIEWS.com and from what I understand, the 9x is pretty popular at the Tokoroa airfield in NZ. His Xjet channel on youtube is another source of entertainment for me.RegardsChristian

author: RCMR
author_rank: Frequent Contributor
timestamp: November 10, 2011, 04:22:11 am
content: Quote from: EEVblog on November 09, 2011, 05:38:45 amThis is my area of expertiseThe best value system on the market at the moment is the Turnigy 9X radio from HobbyKing (they have an Australian warehouse).This is an incredibly elegant (from an EE perspective) bit of kit that uses an Atmel processor and, thanks to the hard work of others, also offers the option of a completely open-source firmware version called ER9X. The circuit diagram for this radio has also been published so "modding" it is a piece of cake -- if you want to add some extra hardware or software functionality.The stock RF system is "okay" (far better than Spektrum's DSM2 for instance) but if you want some extra resilience you can also fit the FrSky FHSS 2.4GHz system which has the benefits of offering telemetry (two voltages and a serial data back-channel) plus user-definable failsafe.Another bonus of this system is that it uses an RF module so, if you want potentially better performance outside "line of sight" (which 2.4GHz isn't so good for) you can fit a 35MHz FM or PCM module and use a matching receiver.QuoteThe Turnigy Accucel 6 is about the best value "4-button charger" on the market. It will charge the whole range of battery chemistries (Li-Ion, Lipoly, LiFePO4, Nicad, NiMH and Pb) with a power out put of up to 6A or 60W (whichever is the lower).QuoteThese 4-button chargers will recharge a decent lipo pack in about 30 minutes (from flat) and a 50% discharged pack in about 15mins.They have a boost-buck converter so you can charge up to 6-cell packs from a 11V-18V source. Most people use their car-battery for this or, if you need truly portable recharge, one of those little 2-stroke generators with a 12V output will do the job.The reality is that with a decent 3-cell 2200mAH lipoly battery pack costing around $14, it's just as easy to take half a dozen pre-charged batteries with you and swap them in/out as needed.Feel free to drop me a line if you want more info or checkmy Youtube channelorRCModelReviews website.

author: EEVblog
author_rank: Unknown
timestamp: November 10, 2011, 07:27:58 am
content: Quote from: RCMR on November 10, 2011, 04:22:11 amAwesome, the Turning 9X it is!Out of stock in the Oz warehouse though.QuoteSounds like a good option worth trying once we start to tweak the range.QuoteYes, I suspect that is the best way. Waiting down in a wet canyon for batteries to charge is not fun, nor a productive use of time.ThanksDave.

author: IanJ
author_rank: Unknown
timestamp: November 10, 2011, 07:38:25 am
content: Hi,Forget traditional RC Tx control, this is how I control my own QuadCopter. For me the Quad is much easier to fly with a proper joystick.Home made, Arduino powered.PS. Not shown is the strap I wear to keep in comfortable.

author: SgtRock
author_rank: Unknown
timestamp: November 10, 2011, 07:50:48 am
content: Dear Dave:--You may want to patent this one. When its finished you may be able to sell it to the military."I have had my results for a long time: but I do not yet now how I am to arrive at them."Carl Friedrich Gauss 1777 1855Best RegardsClear Ether

author: ChrisKiwi
author_rank: Contributor
timestamp: November 10, 2011, 10:44:43 am
content: Here is a guy doing it for a living in New Zealandhttp://youtu.be/xXuXFGwzw0UThis is another great You tube channelhttp://youtu.be/nMxzL7E3Z7s

author: sonicj
author_rank: Frequent Contributor
timestamp: November 10, 2011, 07:04:27 pm
content: i get something like 32 hours on a 11.1V lipo in my modified Spektrum DX7.ianj, i never did get my version of your joystick project working 100% correctly.... i did fly with it though and its a blast! i think i may know where i messed up in the code now that its had a year or so to simmer.-sj

author: ivan747
author_rank: Super Contributor
timestamp: November 10, 2011, 10:28:55 pm
content: Quote from: IanJ on November 10, 2011, 07:38:25 amDo you have a page with info on this? It seems quite interesting.FOUND IT:http://www.ianjohnston.com/content/index.php?option=com_content&view=article&id=32:project-rc-joystick-tx&catid=3:hobbies&Itemid=8

author: philbx1
author_rank: Regular Contributor
timestamp: December 11, 2011, 08:09:00 am
content: QuoteNice informative posting by RCMR and I may just get one of these transmitters also.Haven't searched that much myself for Quadcopters but this guy does great reviews - almostas good as Dave's

author: EEVblog
author_rank: Unknown
timestamp: December 11, 2011, 08:19:37 am
content: Quote from: hissyfet on December 11, 2011, 08:09:00 am"this guy" IS our forums very own RCMR!Dave.

author: philbx1
author_rank: Regular Contributor
timestamp: December 11, 2011, 08:47:47 am
content: QuoteHaha! So I just figured that out after watching another of his FPV videos.Sorry Bruce, apologies. your reviews are as good as Dave's areAnd Dave, your attention to detail and the forum is great!

author: Unknown
author_rank: Unknown
timestamp: December 11, 2011, 11:36:59 am
content: Watching the videos I think that a little bit ofdihedralcan do wonders to the stability of this thing.BTW dihedral is the thing where they bend the wings of an aircraft up in order to bring the center of lift force up and the center of gravity down.Like this:Another thought, if the vertical sticks of the landing gear are brought beneath each motor, the landing footprint can be enlarged making for much safer landings. This also makes the sleds of the landing gear unnecessary saving some weight.actually this one made use of both of these concepts

author: RCMR
author_rank: Frequent Contributor
timestamp: December 11, 2011, 06:03:29 pm
content: I've got a series of quadcopter/multi-rotor reviews lined up for this summer.There's the OpenPilot board, the PIPO board and fist-full of Chinese-made "no-name" boards and some other alternatives.The Chinese are also knocking out RC multi-rotor hardware at an alarming rate and you can pick up some really good parts for give-away prices these days.

author: robrenz
author_rank: Super Contributor
timestamp: January 07, 2012, 04:17:13 am
content: Forget the unmanned quadcopter go for this:http://www.engineeringontheedge.com/2011/11/man-flies-electric-multicopter-thanks-to-sensor-technology/

author: firewalker
author_rank: Super Contributor
timestamp: June 04, 2012, 08:59:39 am
content: Another Idea!http://au.news.yahoo.com/world/a/-/world/13861471/the-orville-copter-takes-flight/

author: firewalker
author_rank: Super Contributor
timestamp: December 10, 2012, 11:31:01 am
content: Nice one.

author: phamuc
author_rank: Contributor
timestamp: November 07, 2013, 01:05:22 pm
content: Hey Dave look for a stable flying platform? Take a look at this:Hexacopter als ServierhilfeHere is a real example of the platform at work:both filmed in Badgastein, Austria