Wow, readers, please do yourselves a favor and watch the linked video in that article! [https://www.youtube.com/watch?v=p8t41avFuCc] though it's slightly WTf-y, it's definitely cool. I'm just wondering - Are heli's better at carrying my Canon DSLR or would the triquad work better for this?? Anyone with experience, please suggest, as I am SO gonna build this tri quad (and integrate it with my Raspberry Pi) :D
A heli carrying a DSLR is big, expensive, hard to fly, dangerous and maintenance intensive. It's good for lifting a DSLR but I would go with a multicopter, the more blades the better. A hexacopter or even an octocopter are very stable, easier to fly, possibly cheaper to build and have a fail-safe, if a motor fails you can land it safely because the other motors take over. You can find a nice video about the subject here:
It demo's a Heli carying a DSLR and afterwards (after the first 7 minutes of video) they talk about this compared to multi-rotors. For the best video results you should probably pick the stable octocopter, you can fly FPV as well with a multicopter, great for live previewing your video.
Though quads are much more trendy in the tech world today, as you can see from that video, plain-old RC helicopters are pretty amazing today. The biggest advance in the hobby IMHO has been the development of very small (~1oz) RC helicopters (e.g. [http://www.bladehelis.com/Products/Default.aspx?ProdID=BLH33...) that include the same fundamental control system (called collective-pitch) that enables these large (~10 lbs) helicopters to be so acrobatic. The size shrink brings huge benefits: Small helis basically don't get damaged in most crashes, they mostly can't hurt you, and they are cheap.
Today's super-stabilized and gps-locked quads are like a modern AAA game: you press "A" over and over and watch them go, and say "Wow!". A micro collective-pitch heli is like an old-school game--you're going to need a lot of restarts, but is great fun and will provide many hours/months of challenge.
Did anyone else watch the linked video of the RC helicopter? It was amazing! I had no idea that those things were so powerful. The only ones I've ever seen are the ones at the mall.
an 18 year old in the NYC area actually was decapitated by one of those hobbytist copters about 2 months ago. Yes, [one of the reports says] Decapitated.
They're already incredibly dangerous. That trick helicopter just needs one uncontrolled bounce and hit a person and someone will have very very unpleasant day.
Quadricopters seem much easier to make safe afaict.
Well, in his case he was an experienced acrobatic RC heli pilot flying in a sanctioned location. Freak accidents happen and when it involves a large scale RC heli, things can go bad very fast. Heck, even medium-large quadrotors can rend flesh quite easily and the small ones can do enough damage to make you respect them afterwards. I have a micro sized quad I fly in my yard because I'm not comfortable flying the larger ones anywhere near people.
EDIT: Also, according to witnesses, the top of his head was 'gone', so while not decapitated I guess, it was basically the same (if not worse).
If we assume symmetric forces, we could assume that the defending force knows of the technology and has developed countermeasures. Yes, an R/C copter flying like this would be difficult(-ish) [1] for a human to shoot down, but for an automated defense system, it would be trivial. They are fragile, and they simply don't move that fast compared to many other weapons. A conventional mortar operated by a well trained crew is more difficult to defend against.
If you're talking about asymmetric forces, then it's a different ballgame, but I'm still not convinced that there aren't innovative defenses. I saw a game show (of sorts) some time ago where engineers competed to develop a solution to a problem given a very limited set of resources. Some of the ideas the contestants came up with blew my mind.
1: And I still don't think it would be all that hard for someone who is talented with a shotgun.
> Its hard for an unalerted human to defend against a fast-moving strike drone flock. Against a civilian - no hope.
So what? It's hard for an unalerted human to defend against a fastpitch baseball to the head too. Because something is deadly doesn't make it practical.
My point is that this is a nonsensical threat (suicide drones) that will not be developed because there are so many effective, and much cheaper methods of neutralizing targets.
I'm not saying weaponized drones aren't a future threat. I'm saying that C4-strapped, wildly-aerobatic weaponized drones are Hollywood threats, not real world threats. The dumb alternatives (bullets, mortars, etc) are too effective and too inexpensive, and the weapons that are high-tech will use more sophisticated attack vectors (like what we're already seeing).
Other techniques are human-attended. Remote drones are very appealing as we've seen for most of a decade now. Anybody can afford them; its anonymous; it comes from above so is hard to anticipate.
Interested in other attack vectors..what did you mean by that?
> Other techniques are human-attended. Remote drones are very appealing as we've seen for most of a decade now. Anybody can afford them; its anonymous; it comes from above so is hard to anticipate.
How is a drone swarm not human-attended in a way that is distinct from existing drone weapon systems? More specifically, what advantages does a drone swarm have over existing drone weapon systems?
I still think you're missing the reason why this is a non-starter. It's not that they're ineffective (although I'd argue that they are of limited effectiveness), it's that there are too many better alternatives.
> Anybody can afford them; its anonymous; it comes from above so is hard to anticipate.
Russian 50mm mortars are inexpensive and readily available on the arms market. You can drag it through mud, drop it, and shoot it with small arms, and it will still work.
It's anonymous, because the high trajectory allows you to fire from an enclosed position, then simply walk away when you're done; remember they're cheap and available.
When you fire a mortar, it travels a long distance and comes from above, so it's hard to anticipate.
Guerilla forces love mortars. They use them all the time. They get the job done.
The SciFi-fantasty drone swarm is far too cumbersome and expensive for guerrilla forces, and it's too much of a blunt instrument for 1st-world powers.
First-world powers don't need kamikaze drones, because they can field larger, more sophisticated drones that are mounted with more advanced sensors and traditional munitions. They can fire on many targets in succession with terribly effective weaponry like a 20mm cannon. They can fire from altitude where you don't even see them. They can fly in-theater, autonomously until the time that they're needed. They can return to base, be reloaded with cheap ammunition, then return to the theater of operation.
There are some very limited scenarios where the weapon system you're proposing makes sense, but it's a tiny niche. There are too many simpler, effective options to acheive the same result. The only thing this concept has going for it is the cool factor, which doesn't count for much.
Ok you can be deliberately dense if you like. Its pretty apparent to me that a maneuverable drone that can navigate urban environments, hover, identify a target then decide to act is quite different from the blunt-instrument mortars and million-dollar airplane drones we use now.
Science-fiction? You just watched the video, and you dismiss it somehow as fantasy?
For instance, for assassination, intimidation, even spying (look in a 30th-floor window, relay audio and video) a rotored drone has no equal.
It'll be amusing to see the expression on your face the first time a quad-rotor drone peers in your window. "Hey! That can't be! It's impractical in the scenarios I've imagined!"
You just expressed several views with which I have no disagreement. Your original statement was:
> However, that helicopter seems ideal for antipersonnel rapid assault. Add an ounce of C4 and how could you defend against it?
I asked some pretty pointed questions about that hypothetical, and you haven't offered any rebuttal. I've also tried to explore their utility from the viewpoint of a guerrilla soldiers and a nation state.
Yes, I believe that small drones will be utilized. Yes, I believe they will be weaponized. Yes, I believe we really should do something about it! I just don't think the small ones will be weaponized in the way you're suggesting (strap on an ounce of C4 and send them in swarms). That's all.
Also, the one in the video doing the tricks is probably optimized to be very lightweight. I guess adding any kind of useful armor would slow it down considerably.
What is your basis for disagreement here? OP pointed to something which literally uses the word "decapitation" what leads you to believe that it's an erroneous use?
Because the article quotes someone who has a misunderstanding of the word "decapitation":
> “I was playing at the park and we came into the clearing and we just saw a body on the floor,” said Maria Delgado, 13. “He was just decapitated — the whole top of his head was gone,”
This is the only quote from those two news articles that contains "decapitation", and indeed the only instance of the word:
> “I was playing at the park and we came into the clearing and we just saw a body on the floor,” said Maria Delgado, 13. “He was just decapitated — the whole top of his head was gone,”
There were pictures on /r/morbidreality (better don't go there) which are said to be from this incident. It was no decapitation but a severe head trauma.
Searching those two pages yielded one instance of "decapitation":
> “I was playing at the park and we came into the clearing and we just saw a body on the floor,” said Maria Delgado, 13. “He was just decapitated — the whole top of his head was gone,”
So I think it's safe to say that a witness report from a 13-year-old who misuses the word "decapitation" doesn't make for a good source.
I dunno, the payload capacity of these things is shocking until you get to Trex 600 size or above, even at that point it's only "ok", definitely not "good".
At that point (& cost) there are cheaper, more effective (what a cold term) and just down right more terrifying ways, to induce terror.
The small UAVs are destined mainly for aerial photography; they are awesome at that, no question.
Ya, if my mission was to weaponize one of these (full disclosure: I've done sw for military UAVs and theater of war information sharing) I'd have it hover/dart above the theater to generate intel and coordinates for conventional weapons.
Is it possible to scale one of those up to Predator-size? Would the limiting factor be that the power requirements wouldn't scale linearly? Are there properties of the atmosphere that model-scale aircraft can take advantage of that larger-scale ones cannot?
Yes. It would be called a helicopter. Full sized ones can have fuel engines, which can carry more energy per weight and can go further. On the other hand, they are heavier and not as durable because of that weight. They cannot change directions like this mid flight.
Mass increases with the cube of scale, while structural material cross-section area increases only with the square of scale. So insects can have miniscule legs, while elephants have tree trunks, proportionally.
Think about it. Ants can carry six times their weight, while larger creatures could never accomplish that. I don't know the physics behind it, but it's not hard to see that small things can have greater strength per mass than large things.
I should say, a weapons equipped version. I can imagine these things being both agile enough to perform in urban environments and fast enough to perform in rural, open environments.
Imagine a dozen of these swarming an objective in Afghanistan, expiring their batteries over the course of a 30 minute attack, disappearing, and just when the combatants thought it was safe, another dozen show up because there is a drone acting as a recharging hive for dozens of these things and it's is doing slow circles around the objective.
That's sci-fi sounding and yet seemingly plausible.
Oh sure, I don't mean to validate the dehumanizing language of the military, it's just how I wrote it. At least I didn't refer to these things as being instruments of kinetic operations.
Not that the machines care much about that, though.
Wow, I didn't know about that. That's ridiculous. I remember watching this comedy bit from Chris Rock about the end of the 'innocent bystander', and I never thought it would actually happen one day.
Of course there is, why else.Obama would explode the 67 year old grandma with a direct hit while she was at.home with her grandchildren while enjoying her flower garden? ( and yes, this actually happened )
Agreed. I was impressed by the RC pilot's skill, and noted the craft's behavior was, at times, very insect-like. Or hummingbird.
... and I couldn't help but think, if a life-size helicopter were even capable of such maneuvers, its human occupants would likely die from the G forces.
Clearly such maneuvers seem only possible in an unmanned craft.
A cursory glance around the internet suggests that these things are capable of 20G manoeuvres (!), far in excess of the human maximum of 5-10G (depending on axis of acceleration).
It varies hugely depending on the axis of acceleration, so given the manoeuvres in the video I opted for the lower end of the spectrum, which is probably a more realistic estimate than 20Gs.
The mall is more "consumer friendly" ;) The video is from someone who lives RC.
I've only seen one live demo of a "pro" RC pilot doing his thing and saying it was awe-inspiring is a massive understatement. These are folks that eat, drink and breath RC and the amount of time and enthusiasm spent is really astonishing. If anyone can find a way around the laws of physics, it's those in the RC community.
How does this perform cross wind compared to a traditional micro quad?
That main rotor will act like an umbrella does in a gust of wind. The micro quads don't suffer the same problem.
I'm not sure of the physics involved (and if anyone knows i'd love to learn more!) but just from hands-on piloting both micro quads and larger helis, the micro quads are some of the least susceptible to cross winds i've ever flown.
Accelerometers are bound to detect such adverse effects. Correcting roll and pitch automatically shouldn't be hard. Also, I would guess that the higher the main rotor (compared to the centre of mass), the more susceptible the device. So, if you build the main rotor as close to possible as the centre of mass, you should have a more neutral design.
While we're at it, I've flown a little toy with two main rotors, rotating in opposite directions, controlling power and yaw, while the tail rotor controlled pitch (the whole thing was auto-stable, so there was no need for roll control). It worked like a charm. So, if we're willing to suffer the complexity of an actual swashplate[1], we could try a design with 2 main rotors, one above, and one below, hereby getting a neutral, manoeuvrable, and (hopefully) efficient design.
AIUI there's all sorts of considerations & trade-offs. E.g. the motors have a limit to how quickly they can change output (up to around 400Hz today).
Because there's no swashplate on the upper rotor of those wee co-axial rotor designs, they're really ineffective in cross wind. You can't apply the required corrective input when the top rotor gets blown off axis.
The design I was thinking about puts the lowest rotor below the gravity centre. First, it would lower the highest rotor, and second, crosswind would have the opposite effect on the low rotor. I really expect such a design to be neutral.
The conventional wisdom is that rc quads are _more_ susceptible to winds than rc acrobatic helicopters (and have lower max speeds) largely because they usually have a "cupped" shape to their props (to maximize efficient static thrust) which can catch catch a cross wind. In contrast an acrobatic rc heli has perfectly straight/flat blades that change pitch to create lift and are quite "invisible" from the side.
That said, in this design, having two different types of rotors mounted non-symmetrically seems bound to induce some yaw from winds.
I always wondered why there are no "real life" sized quadcopters in use for manned flight. From what I understand the design is simpler and requires less maintenance compared to "normal" helicopters.
Are there any reasons why we're not flying quadcopters around instead?
> I always wondered why there are no "real life" sized quadcopters in use for manned flight.
The explanation is simple: quadrotor physics do not scale up. The rotational inertia of the rotors is proportional to the length of the rotor blade to the fifth power. Double the rotor blade length and the inertia of that rotor goes up by a factor of 32.
High inertia rotors are not suitable for quadrocopter because fast changes in the rotation of the rotors required for maneuvering them.
Having one big rotor for lift and three (or more) small ones for control is a very good idea. Another idea that is being researched is having multiple quadrotor copters flying in co-operation.
Mass is not linearly proportional to length, because a longer rotor needs to be a lot heavier to be structurally sound. A uniform rod is not a good analog for a rotor blade. It's not a far fetched idea to think that the mass is cubically or at least quadratically proportional to the length of the rotor.
Unfortunately I can't remember the source where I saw the 5th power figure.
In addition, the aerodynamics of a rotor don't scale up linearly either.
Your assumption is way too simple. Mass increases with the cube of the scale, while cross section area increases with the square of the scale. The cross section will need to increase to cope with the extra mass, and that in turn will increase the mass itself, and this mass is specifically the rotating mass.
There was some crazy man/scammer building a manned flying thing with six snowmobile engines powering six rotors. I remember this because I was working for Ray Ozzie at the time and he was telling people in the office about it because he had invested in it.
I'm by no way an expert on this topic. I just skimmed over the wikipedia article[1] where I read the following:
> First, quadcopters do not require mechanical linkages to vary the rotor blade pitch angle as they spin. This simplifies the design and maintenance of the vehicle.
As already mentioned I'm blatantly ignorant about this topic so it would be nice if someone who knows this stuff could chime in :)
small quadcopters basically speed up and slow down the motor itself to control how much lift is generated. As the size and weight of the blade increase, inertia makes that impractical, so you have to go to variable pitch for control.
For the hobby sized quads, it's simple enough to swap a motor. It is definitely easier to maintain since a spare is only 20 bucks and attaches in minutes with zip ties.
I really like this, because it shows that quadrotor (and flying vessel in general) research is far from "done".
Most people would tell you that you'd be insane to try to design new types of aircraft, because we already know how to do that. This research proves otherwise.
One might almost say that anybody knowing basics of Newtonian mechanics would say maximizing your blade swept area reduces power needed to stay aloft. Then there's stuff like tip vortices etc. So just one big rotor is great.
The problem becomes control. With many small rotors you don't need to control blade pitch, as the electric motors have high torque and the blades are light, so you can control with quick engine thrust changes. And it's that what makes the quad rotor system much more attractive than a normal helo. The traditional helicopter pitch control system is complex and requires precise high stress components that are well built and maintained.
But it's a very inelegant brute force system in my opinion. The pitch control could be improved a lot as well if you have powerful electromagnetics with very precise control.
You still need a tail rotor though.
The real helicopter is seeing some real progress at the moment as well, all in the name of higher speeds. There's Sikorsky's X2 and AVX's modified Kiowa. They have coaxial main rotors with a pushing tail rotor and two pushing fans respectively.
Then there's tilt rotors by Bell and Boeing, IIRC. These were, at least at some point, all part of a US scout helicopter competition.
And then there's the Eurocopter X3, with no tail rotor but twin pulling rotors like a twin prop airplane. X2 and X3 have flown.
No. Try a cheap quadcopter without any auto stabilization. it takes more than 10 minutes. Maybe 8-12 hours of flying time to become proficient enough to, say, risk mounting something breakable (like a camera) onto it.
Less time than a normal helicopter though, so I get your point.
He probably means "stabilized using gyro and accelerometer" (ie, release sticks = evens itself out) as opposed to "just stabilized by gyros" (ie, release sticks, copter stops any rotation but keeps pitched/rolled position).
Sure, learning to hover in one general spot is doable in 10 minutes. I wouldn't call that "learning to fly".
What about very basic maneuvers like landings (no bouncing around, no dropping from too high, and at the spot where you wanted to land) or circles/eights, dealing with ambiguous orientations when your copter is high enough (~ 6m ?), nose-in flying / dealing with control reversal and recovering from orientation loss?
"The researchers explained that the standard "control" quadrotor had an optimized design, while the triquad was not optimized at all (because its design was constrained to keep it as similar as possible to the control quadrotor). This gave the control aircraft an advantage in power of about 9 percent."
I wonder what the optimized "triquad" would have looked like?
This is really cool, and probably a better solution than quadcopters for many applications. However, what we would ideally want in the end, would be a tilt-rotor of some sort which incorporates wings. Fixed wings are a lot more efficient than active lift, and is necessary if you want to squeeze more speed and range out of your UAV.
That's kinda stupid garage-scienticism to be honest.
- TFA does not mention the stability issue. Guess why people and drones fly tri, quads, etc and not regular helis. Yeah. (a simplification: stand on one leg. Now stand on 2, and use your 2 hands as well. 4 legs. Stable heh?)
- Yes single large prop is more efficient than many tiny props. But put many large props and the difference isn't so big. Let's take a $1000 ultra efficient quad: www.youtube.com/watch?v=t0SR5bzuFq4 yeah thats 100min of flight time for something smaller than the Align Trex of the video. And it's cheaper too.. The trex flies 5 to 10minutes (6S 5000mah). At equivalent batteries, the trex flies 25min (hint: the trex is not made for efficiency, it's made for 3D). An average camera-less quad flies 10 to 15min (3S 3000mah).
- TFA compares a $5000 Align Trex 700 with a bunch of expensive upgrades - the top of the top - with one very good pilot with decades of training... to a $200 toy.
- Taking cheap shots about their measures of efficiency is hypocritical. TFA says that the researchers did investigate the efficiency and calculated a 25% gain. Presumably their calculations will be in their research paper. You on the other hand have just given a YouTube video and battery capacities as your 'proof'. Heck, the researchers went as far as constructing a device to test their efficiency claims.
- The stability might be an issue for completely manual flight (but then, people fly ordinary helicopters just fine...) but with computer-assisted balancing, the problem can be much reduced. Even existing quad copters often have computer-aided stability.
I investigated and I say this is wrong. No backup either.
= The point.
Now then again, I actually fly every of these so I pretty much know what the efficiency is.
YES they gain 25% efficiency with the tricopter that has a huge prop in the middle, I TRUST that. But the test is meaningless:
If you change the 3 props instead and put big props, with corresponding motors. Guess what. Efficiency is probably higher than the 25% difference. I actually design my own. In fact, I also design my own control boards (the software that is)
Quadcopters use accelerometers, barometers, gyroscopes and magnetometers (and GPS) to ensure stability.
Guess what. Measurement from these devices isn't 0ms. Actuating the motor control isn't 0ms.
On regular 1 rotor head heli it isn't either. In fact, it's longer.
Result? it's more stable with 4 props than one prop. It has more inherent stability., even if it wasn't "computer assisted". Timecop did a fully gyro stabilized quad copter recently that shows exactly that, if any "actual proof" was needed. Gyro stabilized can be made with no computer whatsoever (like helicopters are/used to be - that's why they're very, very hard to pilot, real ones and RC ones).
The physics makes sense. larger rotors are more efficient because they have lower disk loading. At really low loadings you can lift a human with their own power.
Not to mention simplicity. I suppose it wouldn't matter as much for commercially manufactured rigs, but for hobbyists this thing is a lot more complicated.
Maybe there is something more complicated going on with helicopters that I am not aware of, but a helicopter would not be an inherently stable system due to it "hanging" from the rotor because the direction the rotors are providing thrust changes (all other things being equal), when the helicopter starts to tip one direction.
