124 replies to this topic

[Mr.RC-Cam]

Not much to say other than you might want to visit the Quadrocopter web site. A proto photo from the web site is shown below.

DEAD LINK.

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[s2e3s2z2]

I was actually considering building one the minute I came across the website on Engadget (or was it RC Groups?). Anyway, I'm going to figure out what the total cost will be first, then I'll decide. It's a great platform for AP that's for sure.

[Terry]

Funny you should bring this up, I have been thinking about a quad again lately. As it stands the design dose not offer any advantage over a conventional helicopter though. Maybe if it was built with variable pitch props and high speed servo's it could become more stable.

Terry

[Mark Harris]

Seems to me just using a conventional helicopter would be much better. This thing looks like it would drain a lipo in about 3 minutes where a heli could run for 15 mins on it

[Hartwig]

Mark, I think that's right, they can drain a lot of power, but they can carry heavy loads, too.
But the main thing in my opinion is the stability that they offer. There are about 60-70 developers working together on it, and they are very effective.
I saw videos which prove incredible stability. You could just put the RC-Control aside, go to the toilet and return a few minutes after, and the QuadroCopter will still be in the same place and heigth where you left it, even in windy conditions. It's just amazing.

[Mr.RC-Cam]

To be fair about it, a conventional model heli could be as stable and autonous as the Quadrocopter. In fact, there are commercial solutions that demonstrate this. However, given the serious open source effort going into the Quadrocopter, all the hard work is being done for us. It is an impressive project and possibly one of the few R/C open source projects that has not died off.

[Terry]

The reason I have interest in the quad is because it has the possibility of deploying a parrachute upwards from between the rotors. If it could be made to work it would be a winner for me, even with a shorter flight time.

Terry

[ThomasScherrer]

Terry ?!?! that is impossible !
it will be suck into the rotors and eaten up alive.

but if you release it from the bottom, it will be blown away from the heli
and that will work.

[Terry]

Terry ?!?! that is impossible !
it will be suck into the rotors and eaten up alive.

Ha Ha Ha Maybe I should have explained better. The low inertia of the smaller props would allow them to be stopped very quickly compared to a big single rotor. Then the chute would be thrown/fired upwards through the middle well clear or the props, even if they were still tuning slow it would not matter.

A conventional helicopter would as you said need to fire the chute down wasting precious hight or jettison the blades to be sure they were not eaten up.

Terry

[cyber-flyer]

I saw videos which prove incredible stability. You could just put the RC-Control aside, go to the toilet and return a few minutes after, and the QuadroCopter will still be in the same place and heigth where you left it, even in windy conditions.

That must be with position hold autopilot turned on, regular heli will do the same.

But from agility point of view and resistance to wind gusts regular single rotor heli will beat QuadroCopter any time, they are not even in the same category.

[Mark Harris]

mmmm... jettison blades... sounds like explosive bolts and blades flying everwhere... i like where this discussion is going!

[ThomasScherrer]

ahem, stop blades a single sec ?
and how fast will the heli fall and fail ?
dont even think about it, I say.
better just fly hi enought and release it nice and easy from the bottom side.

[Terry]

With the dynamic brake the prop on my plane cuts to zero thrust in an instant and stops completly in about 1/2 second. By the time the chute is deployed the props will not have any effect. The chute should then be fully open with only a 50ft fall ( if my model rocket friend is right ).
Anyway I'm still not convinced a quad copter is worth the trouble, it's still on the 'maybe one day list'

Terry

[Kilrah]

ahem, stop blades a single sec ?
and how fast will the heli fall and fail ?
dont even think about it, I say.
better just fly hi enought and release it nice and easy from the bottom side.

A friend of mine often has some fun with his draganflyer quad, stopping the 4 blades in the air at and starting them again. No problem, he only loses about 10m or less.

[Arthur P.]

Besides the UAVP project (http://www.uavp.de/) there is also the Mikrokopter project (http://www.mikrokopter.de/), both quadrocopters which claim to have airtimes of 10-20 minutes on 2-3A 11.1V LiPos using 2x2 pairs brushless motors with 10x4.7 (counterrotating) props, both capable of lifting up to 2 lbs. Some of the videos on the mikrokopter site are amazing, i.e. flying in a full storm, or position hold with GPS where the thing gets pushed away forcibly and just returns to its position on its own. Also some nice vids and photos on the UAVP site.

Some major differences between the two projects:
* different microcontroler: the Mikrokopter controler wants 4 servo signals multiplexed over a single input port, while the UAVP just accepts separate Rx outputs as input. So the UAVP is usable with almost any Rx.
* the more expensive UAVP kits at least provide partially mounted components on the PCB, while with Mikrokopter you have to order all the electronics separately in addition to the PCB and solder everything on yourself.
* the most expensive UAVP kits even come with very nice high-tech looking precut frames, while with Mikrokopter you are expected to put your own frame together. The frame of course s very simple and can cost as little as USD 5.00 in aluminim tubing from the local DIY.
* UAVP kits come with commercial 30A ESCs while with the Mikrokopter you order PCPs and components for Holger's 20A ESCs. If I understood it correctly the ESCs are a very critical component as they have to be able to switch at very high frequencies to stabilise the craft. Same goes for the gyros. Don't expect to be able to cook your own with just any brand of ESCs and gyros.

For the UAVP, and I believe also for the Mikrokopter, you have to set up your transmitter either to heli without any swashplate mixing, or to simple glider/airplane mode. In RC Groups in the VTOL forum there are several successful examples of quadcopters and tricopters using only gyros, v-tail mixers and ESCs, no microcontroler. In those projects the transmitter does the "swashplate mixing". Downside of this approach is that you cannot integrate further sensors such as the accelerometers and air pressure sensor which help futher stabilize the quadrotors and allow a reasonably accurate altitude hold function. Don't believe anybody has integrated GPS in those non-microcontroler qaudrotors either.

[Arthur P.]

The big advantages I see of these quadrotors are:
* small size (either 35x35 or 50x50 cm square depending upon the frame used), and the better frames can be easilly collapsed or partially disassembled making transport a lot easier, and potentially allows the system to be taken along on bussiness or holiday trips
* low cost of parts. Yes you need 4 motors and 4 ESCs, but mechanically these things are extremely simple, with crash repairs usually limited to 1 or 2 new slow-fly props. Compare that with a minor crash with a TRex 450S which still has a larger "footprint" with its 75cm rotor, which cost me a new rotorhead, flybar, main axle, landing gear, tail rotor servo and tailrotorhead (approx. Euro 125.00 in repairs)
* low risk of mechanical failure. Check your props are fixed properly regulary. There isn't much more which moves.
* relatively low risk of electrical failure. The ESCs are relatively highly rated relative to power used so I would hope they wouldn't burn out often.
* no big rotor spinning with high energy. In particular the latter aspect has made me decide to sell my newly build but untested Logo 14 in favour of the UAVP. I just don't feel comfortable flying a thing with 55cm long carbon blades spinning around at 300mph anywhere near people and my primary targets for AP tend to be densely populated with people who want to come and look at the marvels flying overhead (e.g. holiday resorts).

Although the UAVP site advertises an optional parachute system, I haven't seen it offered for sale. I have found other sites on the internet which do offer RC Aircraft parachute systems. The UAVP microcontroler does seem to have an output to deploy such a system. So I guess integrating is an option worth considering. These things have one big downside: if a motor fails (propellor loss being the most frequent cause), they come down like a 1-1.5kg brick. So a parachute system is worth considering if working overhead although the risk of accidental deployment must be weighed against the risk of catastrophic system failure requiring deployment.

The alternative is to build in more reduncy. There are some very interesting examples of hexacopters (3x 2 counterrotating brushless motors) and octocopters (4x 2 cr bl motors), with one video of an octocopter even showing the thing --which I believe can lift 2 kg or so-- take off on 7 motors, and then be attacked by a guy with a branch who manages to trash an additional prop, but it just flies on to a safe controled landing on 6 motors.

Another way to reduce risk if of course to change flight habbits to e.g. go straight up from the LZ, hover and shoot while rotating to get a pano at a given altitude, shut down the throttle for a vertical drop down, going to full throttle a couple of meters above the ground (you can see that being done in some of the videos), move to the next location and repeat the ascent / descent approach, and thus avoid wandering around to widely over the public at altitude.

Besides the lack of autorotation capability, the other big disadvantage is the quick loss of orientation. There is an MD4-200 model for FMS. Try figuring out what is front and back and its horizontal plane after flying it to the end of the runway. Good chance you'll hit the ground before you figure out your orientation.

As indicated I-ve ordered a full blow AUVP D4 kit (with high tech alu frame). They should be in stock again in the first week of June so I-m hoping for delivery in the first or second week of June. Once it's in I-ll start a build thread in the aerial photography forum in RCGroups.

[Terry]

Many thanks for your posts Arthur, fantastic info !
I have a big Vario Heli that I am tempted to use for AP but these things are making me question if I want to use it. I will hold off a bit longer while I look into it

Terry

[ThomasScherrer]

hum,
I have never heard or seen the word Quadrocopter before
when I started to construct my own, several years ago,
http://www.webx.dk/rc/4heli/index.htm

back then I got the idea to call this thing Quadrocopter,
since I could not call it dragon flyer rip off, hehe

I even won a price "new design" for it at a RC model show !
so no one else have seen it before back then..

http://de.wikipedia....ki/Quadrocopter
but today it is common knowledge :-)
and I see now that the word Quadrocopter is not my own invention.

[Arthur P.]

You were way ahead of NASA. They are currently looking at a quadrocopter design for a future Mars explorer !

[cyber-flyer]

http://www.rctoys.co...OMPARE-ALL.html

RC-toys was selling their quadrocopter under the name draganflyer for at least couple of years now. Few heli pilots at the local field bought it, only to sell it back as they were not impressed with their flight chracteristics.
One disadvantage is that their props are fixed pitch and they will have tendency to baloon in the wind gusts.
I watched videos on Mikrokopter site - they look good. The video in the storm shows balooning effect as the model get thrown up and down. But I have to admit - for the model of that size it wasn't bad.