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Old Mar 18, 2010, 12:45 PM
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Advice for a 30-40 cm size Quadrotor build

All,

I have been reading and posting around here for quite a while, more than long enough to have built several quads by now. I'm sure an experienced quad builder could give me some advice as to frame/motor/prop/ESC/battery combinations that would work for me. Alas, I do not have the inclination, tools, or patience to scratch build, so I would like to buy as much as I can pre-built. I don't even have any r/c equipment or experience. But, I do have a custom controller board that my friend designed: http://www.rcgroups.com/forums/showthread.php?t=1075426

My objective is to have an initial platform that's reasonably capable (I'd like to do some simple aerobatics eventually) for use in developing autonomous and semi-autonomous algorithms.

Here are my requirements/goals:

- Required tools: No sawing, dremeling, or anything else that leaves small particles. Just screwdrivers, pliers, and the like.
- Minimize soldering or eliminate if at all possible
- Desire to have at least twice as much max thrust as weight
- I'm willing to sacrifice flight times for weight savings and/or extra thrust

- Approx 30-40 cm frame (motor to motor)

Candidates that I'm aware of:

30 cm MikrKopter frame
http://www.nghobbies.com/cart/index....roducts_id=322
Recommend motors Roxxy 2815

40 cm MikrKopter frame
http://www.nghobbies.com/cart/index....roducts_id=248
Recommended motors Roxxy 2824-34

NoVa frame (12.6 inch)
http://www.rcgroups.com/forums/showthread.php?t=1203460
Recommended motors - hacker A20 & Hacker clone

- 8 inch propeller
I'm presuming with this size frame I'd want an 8 inch prop, either APC SF 8x3.8 or the EPP equivalent

- Motor
Besides the above,
Tower Pro 2410-09 or KDA 20-22L or Hextronik (1300kv). Has to be compatible with the frame mounting holes and prop

- ESC
Turnigy 10-25 amp, HK SS 18-20 (desire to be capable of 400Hz operation)

- Battery
??

- Radio
At least a 5 channel (4 sticks plus a switch for alternate control response moding). I don't envision having a fleet of RC craft, so I'm tempted to go for a simple relatively inexpensive model

Any help in picking a compatible combination would be greatly appreciated. It doesn't have to be the best or most expensive, but I'd be willing to pay a little more for ease of construction.

- Roy
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Old Mar 19, 2010, 10:44 AM
a little boy's dream come true
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good idea of a thread, smaller quads are not very documented... yet

Quote:
Originally Posted by AntonK View Post
I can say I have heard pretty good things about the 1350 3S batteries from hobbyking
I totally agree with this : 3s - 15c around 1500 - 2200 FlightMax for example

Bob
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Last edited by bob.titus; Mar 19, 2010 at 11:49 AM.
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Old Mar 19, 2010, 11:30 AM
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I cannot comment on the frames as I am a bit biased however this seems like a very fun project and you have started a good list. I can say I have heard pretty good things about the 1350 3S batteries from hobbyking.

AJ
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Old Mar 20, 2010, 09:12 AM
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Quote:
Originally Posted by bob.titus View Post
good idea of a thread, smaller quads are not very documented... yet

Bob
Bob
That's why I'm asking. But it does no good if no one replies

Quote:
Originally Posted by AntonK View Post
I cannot comment on the frames as I am a bit biased however this seems like a very fun project and you have started a good list. I can say I have heard pretty good things about the 1350 3S batteries from hobbyking.

AJ
AJ,
Do any of your customers have a build log or can you or they share their component choices and experience?

I should point out that I'm not really interested in aerial photography or large payloads (though I will probably use one of those keychain "spycams" for the fun of it). I'd rather be doing stuff like this (eventually): http://roboticcircus.blogspot.com/20...ome-flips.html

Thanks
Roy
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Old Mar 20, 2010, 12:06 PM
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Roy,
Great question. Currently all the frames are used for Paparazzi Booz testing. I have made a video showing how the frame goes together, it takes all of about 5 minutes to assemble from the kit. If you are looking for a component breakdown, its really dependent on your flight controller and what you are looking at doing. We have flown 4 different speed controllers(an 18 and 6 amp chinese i2c conversion), a custom 10 amp controller, and the asctec X-BLC controllers. We have flown 2 different hacker clones as well as the hacker A20s provided on the X3d. I have flown 2 different sets of flight controllers however both were Paparazzi related. I have flown the full Booz hardware suite, and on another quad which was built for durability testing we installed a Paparazzi AP board and a commercial IMU.

If you have any other questions feel free to ask. Feedback is always great on a new product like this.

AJ
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Old Mar 20, 2010, 05:04 PM
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Quote:
Originally Posted by AntonK View Post
Roy,
Great question. Currently all the frames are used for Paparazzi Booz testing. I have made a video showing how the frame goes together, it takes all of about 5 minutes to assemble from the kit. If you are looking for a component breakdown, its really dependent on your flight controller and what you are looking at doing. We have flown 4 different speed controllers(an 18 and 6 amp chinese i2c conversion), a custom 10 amp controller, and the asctec X-BLC controllers. We have flown 2 different hacker clones as well as the hacker A20s provided on the X3d. I have flown 2 different sets of flight controllers however both were Paparazzi related. I have flown the full Booz hardware suite, and on another quad which was built for durability testing we installed a Paparazzi AP board and a commercial IMU.

If you have any other questions feel free to ask. Feedback is always great on a new product like this.

AJ
AJ,

My friend's board has provisions for PWM-based ESCs. Can you specify which "chinese" ESCs you used?

I like the weight of your frame, but for the price I could buy 2 mikrokopter frames and have 100% spares. How "crash worthy" is your frame? Also, I like the idea of landing skids to keep the rotors further away from ground effect. I know they make such skids for the mikrokopter frames. Have you tried any skids with your Nova?

edit: As long as I'm asking, what is a typical AUW for quads based on this frame.

- Roy
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Old Mar 20, 2010, 05:43 PM
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Hi RoyLB. My latest frame is 40.6 cm motor to motor at 544 grams AUW. I'll try to get some flight times for you to help with the battery selection. I have a 2200 and a 1800 battery I can test and so far the 2200 appears to be doing well.

I'm using the SuperSimple ESC's with no problem. I don't know if these have the best resolution so the Plush 10amp should also work.
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Old Mar 20, 2010, 05:44 PM
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8 inch props should do well with the 1300 KV motors.

My 40$ turborix TX is working fine but it's nice to have digital trim readouts so you can center them, calibrate sensors and stick mid points, then move the trims back to where they were so your quad flys straight.
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Old Mar 21, 2010, 03:38 PM
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Roy,

With regards to speed controllers, Ive used the TowerPro 18A

http://hobbyking.com/hobbyking/store...eed_Controller

And the Turnigy Plush 6A

http://hobbyking.com/hobbyking/store...eed_Controller

As far as the frame price, its really a matter of materials. the MKK frame is square aluminum tubing and fiberglass. The NoVa frame is Carbon fiber plating along with a Carbon-Balsa-Carbon sandwich. This material is much more expensive but also is much stronger than the aluminum and fiberglass. My first prototype frame was very similar to the MKK design and I was constantly bending back the aluminum arms in a vise after mild altercations with the ground. The NoVa frame has a few nylon fasteners that have been placed based on flight testing to help minimize damage due to ground impacts. While I will not make a claim that its indestructable, I have yet to replace a major component in the 200+ flights I have. The only parts I have replaced are the nylon screws that are designed to give way.

Lastly on the subject of AUW. Ive flown my quad from 375-475 grams.

Great questions again

AJ
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Old Jul 05, 2010, 09:58 PM
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New inspiration

Wow - no activity since March! Has it really been that long? Time flies. I'm probably the world's only quad designer who doesn't own a quad

After seeing this video on aggressive quadrotor maneuvering (that I'm sure you've all seen),

Aggressive Maneuvers for Autonomous Quadrotor Flight (1 min 27 sec)


I realized that my quad would be of similar size (not that I expect to be able to perform the same feats that the U Penn guys did - at least not without my own multi-thousand dollar motion capture system). I realized if I could get my quad to have similar specs and/or components as the Astec X-3D, it should be capable of some impressive aerobatics.

So I re-read the designers' original paper (http://www.societyofrobots.com/robot...d_at_1_Khz.pdf), listened to the DIY Drones podcast of Daniel Mellinger, the U Penn PhD student who made the video http://feedproxy.google.com/~r/diydr...isode%2026.mp3, and perused this RCG thread http://www.rcgroups.com/forums/showthread.php?t=950768.

Here's what I found:

The X-3D can certainly be purchased . Daniel said the research version cost around $4000 . There are some lower priced hobby kits, but even they are over $1000. It has custom BLDC motors, props, ESCs, frame, and controller boards, which can also be purchased separately, and are also very expensive (http://www.xufo-shop.de/).

Here are the specs of the X-3D, as near as I can tell (perhaps someone can correct these if I am mistaken). I don't know if the research version has the same specs or not:

Frame:
Size: 32cm without propellers
All-Up Weight: 400-500g with battery
Flight time 30 min (no payload)

Motors:
weight: 27.5 g
Kv: ~1000 RPM/V
thrust: 330g (with custom prop)
Thrust to weight ratio: 2.5x

Propellers (custom):
Size: 19.8cm = almost 8 in

For my quad:

Frame (NoVa)
Size: 12.625 inches = 32 cm
Weight (Frame-only 77g)
All Up Weight: approx 430-500 (depending on details)
Flight time 26-36 min for pure hover (according to MotoCalc).

Props: APC 8x3.8 slowfly

Motors:
The nearest common motor I can find is the Hacker A20-50S (http://www.rctoys.com/rc-toys-and-pa...-HACKER.html):
-29g
-100W
-1088 RPM/Volt
- 2 cell LiPo recommended.

Since I am inexperienced with rc motors and flying, and am writing my own software, I'd like a cheap motor so that if one breaks due to the inevitable crash and/or software bug, I'm not out that much money.

This seems to be the closest clone motor - Keda or KDA20-50S hacker Style Brushless Outrunner 20-50S. Which is available here:
http://www.hobbyking.com/hobbyking/s...idProduct=4699
and here: http://www.nitroplanes.com/a2haoubrmow1.html

Does anyone have any experience with either motor, or dealing with either company? Any performance measurements out there? I assume the HobbyKing version does not have the bullet connectors attached, but its impossible to tell in the picture. At least they provide relevant parameters, so it is possible to use MotoCalc and other such programs for some predictions.

I also found this Turnigy with similar specs: TR2205/50 2205 50turn 1088kv 8A Outrunner
http://hobbyking.com/hobbyking/store...idProduct=5685
However, I couldn't find the no-load current nor resistance, so I couldn't compare via MotoCalc. Does anyone have any data or experience with this motor? How does it compare to the Hacker clone?

I will start an actual build-log thread, once I have the parts.

Thanks
Roy
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Old Jul 06, 2010, 10:18 PM
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Old Aug 01, 2010, 02:20 PM
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I finally started my build log here: http://www.rcgroups.com/forums/showthread.php?t=1284741

- Roy
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