Propeller with propellers

[JasonDorie]

In my design, the rotors are paired like this:· (CW = ClockWise, CCW = CounterClockWise)

CW    CCW
  \   /
   \ /
    X
   / \
  /   \
CCW    CW

If all rotors rotate at the same speed, the sum of the motor torque is zero.· To move left, the left pair slows down and the right pair speeds up, resulting again in a net torque of zero.

To change heading, one diagonal pair speeds up and the other diagonal pair slows down, resulting in a non-zero net torque, but identical net thrust.· I believe this is the same as the DragonFlyer.· Most quadrotors I've seen are arranged like a '+' instead of 'X', which seems odd since the '+'·layout produces some yaw torque when doing pitch or roll moves.

Jason
·

[Timothy D. Swieter]

Thank you for the details. I hadn't realized your layout was more of an X than a +. I will have to read more on that.

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Timothy D. Swieter, E.I.

www.brilldea.com·- Prop Blade, LED Painter, RGB LEDs, uOLED-IOC, eProto fo SunSPOT, BitScope
www.sxmicro.com - a blog·exploring the SX micro
www.tdswieter.com

[Timothy D. Swieter]

Thank you for the details. I hadn't realized your layout was more of an X than a +. I will have to read more on that.

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Timothy D. Swieter, E.I.

www.brilldea.com·- Prop Blade, LED Painter, RGB LEDs, uOLED-IOC, eProto fo SunSPOT, BitScope
www.sxmicro.com - a blog·exploring the SX micro
www.tdswieter.com

[jcpole]

Hi Jason...

Awesome job with hovering - where did you get those motors? I've been looking high and low for something strong enough (read as: generating enough lift) to lift a few batteries, controller hardware, and a camera into hover. Constant-speed (variable propeller blade pitch) props would be incredible, but I don't think anyone can shrink the mechanism down far enough to use in "hobby" engines. I've been experimenting with vectored thrust systems, which might be more stable than an anti-torque approach.

I'm a pilot, and this all seems so simple from inside the cockpit - most likely because I've never had to build my own aircraft from scratch.

Thanks!

Jamie

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--
Jamie C. Pole
Principal Consultant
J.C. Pole & Associates, Inc.
http://www.jcpa.com/

[JasonDorie]

Jamie,

It all depends on how much you plan to lift.· The one shown in the video pulled about 35A, and would probably lift 7 or 8 lbs, including itself (it weighs 3), but would only fly for 6 minutes on those packs, and produced more air speed than required.· The current version (all I changed was the props) will lift less weight (5 or 6 lbs) but will fly for 12 minutes on the same packs.· Going to lower RPM/Volt motors turning larger props would generate less thrust speed, but more overall lifting power.

I bought the motors from http://hobbycity.com, but there are lots of places that sell hobby motors with the kind of power you're looking for.· There are also variable-pitch systems available, though they tend to be for small planes.· I've considered using tail assemblies for a model helicopter to see if that would work, but I suspect the paddle-style props aren't as efficient as what I'm using now.· The servo to drive the pitch would add weight, but would make the thing more responsive, and able to fly inverted.

For inexpensive stuff, I usually look at HobbyCity, NitroPlanes, or BPHobbies.· For better quality, but higher prices, check out Hobby-lobby, HorizonHobby, Tower Hobbies, or plenty of other online places.
I'm planning to augment the anti-torque thing with movable motor pods.· That will give me both forward flight, and far faster rudder response in a hover.· The left/right motors will tilt fwd/back to spin in place, or all tilt forward for normal flight.
Jason
·

[jcpole]

Thanks Jason...

Jamie

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--
Jamie C. Pole
Principal Consultant
J.C. Pole & Associates, Inc.
http://www.jcpa.com/

[JasonDorie]

I got video of the latest version today.· The software has been tweaked a little, and I switched to lighter, lower-pitch props to allow the motors to run more efficiently.· I now get ~12 minutes of flight on 4Ah.

http://jasondorie.com/WordPress/?cat=3

Jason
·

[Timothy D. Swieter]

Way cool!

Jason, you really should put these videos on YouTube so others can be inspired by what you are creating.

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Timothy D. Swieter, E.I.

www.brilldea.com·- Prop Blade, LED Painter, RGB LEDs, uOLED-IOC, eProto fo SunSPOT, BitScope
www.sxmicro.com - a blog·exploring the SX micro
www.tdswieter.com

[JasonDorie]

Done - Just for you. :)

[Cluso99]

@Jason
Love the Youtube video :-)

I am building an EPP Delta Wing and bought my gear from Hobby City. Shipped to Australia in 5 days.

You have just wet my appetite - maybe when I get this wing working (read: learn to fly) I might try something like yours. Would be a great use for my propeller too. Always wanted to play with gyros, accelerometers, etc.

Have you thought about·using 4 EDFs (fan engines)?? Thinking about something along the lines of a flying saucer (UFO).

I'll keep a look out for your updates.

[Timothy D. Swieter]

A long time ago I ran across this video and web site:

http://hk.youtube.com/watch?v=Y4jtguSF0n4

http://www.microdrones.com/index.html

Those sites inspired me to build my own, but that particualr project hasn't gotten off the ground.· Perhaps when I return to the States some day and I have a real workshop to build things.· I remember doing research and found some college student projects with papers that were interesting to read.

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Timothy D. Swieter, E.I.

www.brilldea.com·- Prop Blade, LED Painter, RGB LEDs, uOLED-IOC, eProto fo SunSPOT, BitScope
www.sxmicro.com - a blog·exploring the SX micro
www.tdswieter.com

[JasonDorie]

Tim: That's really cool. I think I've seen a video of one of those before (the big loops under the arms look familiar). I'm thinking I might have to build two of these - One to play with autonomous flight (self levelling, compass & GPS, camera, etc) and another one to be the Wolf Spyder project that I originally started this for. Both are compelling to me, and while they're quite similar, I never really intended the Spyder to be 'self piloting', but it's a cool challenge. I haven't decided yet.

Off topic, I write a video processing app for a friend of mine who runs a night club. (http://midivid.jasondorie.com) I really liked your DMX living room lights. :)

Cluso - Yeah, I've pretty seriously considered using EDFs for this thing, and still might try it. They're less efficient than props, but will produce much more speed when I'm in forward flight, and have the added bonus of the protective casing around the props. I'm not sure how responsive they'll be, but I've been itching to try it. Just the thought of that high pitched jet-like whine makes me smile. :)

Jason

Post Edited (JasonDorie) : 10/27/2008 8:28:57 PM GMT

[Cluso99]

@Tim: Great links. I love one of them!!!

[simonl]

JasonDorie said...
I've pretty seriously considered using EDFs for this thing

I've drooled over that thought to, but then I couldn't find anywhere that had CW & CCW fans :-( If you know of any...

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Cheers,
Simon
-------------------------------

www.norfolkhelicopterclub.com

You'll always have as many take-offs as landings, the trick is to be sure you can take-off again
BTW: I type as I'm thinking, so please don't take any offence at my writing style

[JasonDorie]

Simon,

My final design will include 'mobile' props (like an Osprey), and in that case it's trivial to use vectoring for yaw control. If I made one with EDFs it wouldn't behave any differently, though it'd probably always have a slight amount of yaw dialled in to compensate for the higher rotational torque.

Jason

[mikediv]

Hey Jason I ordered all the parts and built my subframe, Thaks for the info by the way, one more thing. What do you use for a remote control unit I have a few Futaba's for some monster trucks nothing serious the whole kit cost me under 150 bucks
·· Could use any info on which one you recommend. I also bought that 6 channel Ar controller basically I ordered everything we discussed I am also not clear on wether I need to order any extra stuff to mount the propellors
I ended up buying a few differant sizes becuase I went with bigger motors but nothing in the doc says anyhting about mounting the propellors??
Thanks man I will post it when I am done.
·

[JasonDorie]

Hey Mike,

Sorry I didn't see this before - To mount the propellers to the motors you usually need a prop adaptor, but it depends on the motor (some come with them) so it's hard to say for sure.·· For the receiver, I just used whatever was around - The code I use doesn't require a specific receiver, as long as it has normal servo outputs you're good.· Keep the antenna wire away from the motors.· :)

I've started modelling the final structure, and now have to work out how to build the thing, and mount the directional propellers:· http://www.facebook.com/photo.php?pi...7&id=671403972

Jason

[cgates]

mikediv said...
Hey Jason I ordered all the parts and built my subframe, Thaks for the info by the way, one more thing. What do you use for a remote control unit I have a few Futaba's for some monster trucks nothing serious the whole kit cost me under 150 bucks

Do NOT use a ground radio for any type of aircraft, it is against FCC rules.

Also, if someone with a ground based vehicle see's you in the air and figures,
"heck he has an aircraft, I'm safe to switch on without checking"...well, let's say
everyone could be ducking for cover if he's on the same channel as you.

Jason, nice job!

[hinv]

Very impressive! I saw some multi thousand dollar carbon fiber quad propeller thing and thought it would be really nice to have, even to make money with(building inspections). But yours, built for a few hundred dollars! Very nice.
How high have you flown it?

Thanks,
Doug

[JasonDorie]

I haven't flown it terribly high yet (maybe 15 to 20 feet) but I don't have a yaw gyro on it yet, and have almost no indication of where the front is, so I'm not as confident with it as I should be. I've gathered all the parts I need to make version 3 of the hardware, so I should have a new version soonish.

Jason