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Old Apr 29, 2015, 11:50 PM
JulietKiloMike is offline
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Build Log
PeasantCopter; an affordable plywood miniquad

Hi All!
I'm a high school senior over at Menlo School in California. I've been a model flier for a few years now, with some experience in fixed-wing and multicopter LOS and FPV flying. For my senior project, I'm designing and building a 250-size miniquad frame from scratch. This will be my first miniquad build, so I'd like to take some suggestions from more experienced builders about what to aim for, what to avoid, etc. If you're an experienced miniquad pilot, I'd love to hear from you, too! This will be a design completely from scratch, so let me know if you have any favorite features in current designs or gripes about shortfalls with the rigs you've flown, and I'll try to incorporate them into my design.

I have no illusions that this will work perfectly on the first try, but I'm happy to crash and learn a few times before I get to a workable design--that's what the hobby is all about!

For now, my main design goals are as follows (again, please let me know if you think something should be added to this list)
durable frame that can take a beating / the aggressive adventures of an FPV newbie (me) while protecting the expensive electronic goodies inside
small(ish); fits within the footprint of current common miniquads like the blackout / mxp230, etc
easily replaceable parts
convenient access to electronics, batteries, etc
durable
fun to fly
durable

The design process will a bit of a dance between making the frame too heavy and too flimsy, and will be made a little more complex by the fact that I don't have carbon fiber or a CNC mill handy for the build. I do, however, have access to a laser cutter, a 3D printer, and some basic building materials like acrylic, plywood of various thicknesses, and some carbon tubes to stiffen stuff up.

Words of encouragement, constructive criticism, wise anecdotes, funny stories, and popcorn emojis are all greatly appreciated. Fire away, and thanks for stopping by!

-John

Edit: I've changed the thread title to reflect the new name of the miniquad. The miniquad is still in the very early stages of development and is not currently for sale (I don't even know if it's going to work yet ) If you are interested in being a tester for PeasantCopter, PM me or shoot me an email at info@peasantcopter.com Other details can be found at http://peasantcopter.com
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Old May 04, 2015, 04:39 PM
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The parts for the quad came in from Multirotor Superstore earlier last week, so I've started measuring them in preparation for design sketches and CADing.

Attached below is a scaled preliminary sketch of the side profile of the quad, with each grid square corresponding to a square inch of area. One of my main design intents was to move the battery as far forward as possible in order to avoid the tail-heavy CG issues faced by most miniquads; the flight controller and rx are housed in a short area under the battery, allowing the Lipo pack to be placed further forward than on most quads.
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Old May 10, 2015, 07:54 PM
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Built a case for my new transmitter, old transmitter, and FPV stuff!

Build details can be found on my blog post: http://www.rcgroups.com/forums/showthread.php?t=2409989
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Old May 12, 2015, 11:54 PM
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I've made some significant progress in CADing the miniquad, which has since been christened the PeasantCopter. Without fasteners, the CAD program is estimating the frame weight to be around 130g--heavier than a carbon fiber quad, but not too bad. I've attached a dimensioned drawing of the quadcopter as it stands now...I'd love to hear what you guys think!

-John
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Old May 13, 2015, 02:28 AM
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Can your CAD software do rigidity analysis? Adding that to the weight calculation would be a great help. Which CAD software do you use?

I'm currently flying an acrylic frame I cut in a laser at work, 166mm motor to motor. It's a simple one plate design but it flies nicely. For your size, you'd want at 1/4" thickness, maybe thicker. I'm currently trying to figure out if I can improve by going from 3/16" to 1/4" but add more cutouts and be as rigid and lose some weight. The laser is pretty quick and material is cheap ($1.70 scrap bin acrylic), but it'd be nice to iterate in software!

Keep posting, I look forward to seeing more progress!
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Old May 13, 2015, 10:53 AM
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Thanks for dropping by, cdog!

I'm using Autodesk Fusion 360 on my mac; it has curvature analysis but I dont know if it can to rigidity analysis. I cut some arms to test things out the other day and they are very, very rigid, even with the cutouts. I'm hoping the sandwiched plywood plates will add to that. I'll cut some parts out later this week to see how things go!

An acrylic quad sounds like fun...what's your AUW?

-John
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Old May 13, 2015, 01:37 PM
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http://PeasantCopter.com is live! Just finished coding it last night
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Old May 13, 2015, 10:42 PM
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The first prototype frame has been cut and assembled! Now to work out some of the kinks and install electronics
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Old May 14, 2015, 08:34 AM
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Impressive work so far! I'm a sucker for wood quads... I'd like to take that thing, stain it, and clear and sand it about a hundred times until it was beautiful. Weight be damned

Looking forward to the finished product... I'm impressed this is the work of a high schooler, maybe there is hope for the future after all.
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Old May 14, 2015, 11:03 AM
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Thanks BuffaloJustin! I'll be sure to keep you guys posted--I'm working on installing the electronics right now. Let's see how she flies!

-John
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Old May 15, 2015, 12:24 AM
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Motors, ESCs, PDB, and Naze32 installed (well, almost...).

The slots for the motor screws are TIGHT, but I'll have trouble making them any larger without making the walls too thin. Installation is a little tricky but it makes for some extremely solid motor mounts.

It seems like the extended battery shelf design does help with CG. The quad was able to balance OK with a 4S 3300 mAh battery pretty well, but I forgot to velcro the battery in and it slipped off and landed on some tools on my workbench Now it's got a suspicious-looking puncture in the plasctic shrink-wrap and I can't remember if it was there before. I'm treating the battery with caution for now, as I'm not sure if the actual battery cells have been punctured or are leaking. Hopefully things are OK (that battery is $70 ). If there are no signs of leaking I'll take a closer look at the opening and might make a very cautious attempt to charge the battery in a fireproof container sometime soon.
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Old May 18, 2015, 03:30 AM
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Motors have been installed and wiring is almost done, but I just found out that one of the CCW Sunnysky X2204's from banggood was defective. It's only got around half the torque of the other motors, reaches a lower RPM, and occasionally makes weird noises when spooling up. My hunch is that one of its phases is shorted or disconnected in some way...I've ordered another motor from BuddyRC in case I can't fix the current one, and that should be here sometime next week.

In the meantime, I've been revising the current design to make PeasantCopter 2.0 I've fixed some of the issues I've experienced with the arms (added clearance for flight controller mounting screws, widened screw holes to provide clearance for M3 screws), and I've also added slight "bulbs" to the end of the arms. I noticed that the edges of the sunnysky motor bell housings protrude slightly over the edges of the arms on PeasantCopter 1.0, so hopefully the arm modification on 2.0 provides a bit of a bumper to protect the motor in case of a crash.

I also changed the side plating up front to provide a small "underpass" for ESC power wiring. This way I can avoid having to pass the wires through the closed holes on the side plates, and can just sandwich them between the side plate and the main bottom plate of the frame, which should save some soldering work in the future

Additionally, I moved the FPV antenna mount to the side and changed the cutout pattern on the front top plate to allow space for mounting a Mobius actioncam (woot!). I don't have one, but some of the people who I'll be sending the frame to do have actioncams, so hopefully this will help them out a bit.

Oh, and I also added a cutout of the frame's name to the top back plate for lolz. I've attached an image of the updated frame; modified parts are shown in gray, while plywood parts are the same as the previous revision.
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Old May 18, 2015, 06:35 AM
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This is a pretty cool project, and all the more so coming from a high schooler - I've always loved wood quads - bluesky rc is one of my favorite frame makers - their laser cutting is the best I've ever seen - the parts go together so well you almost don't need to glue the joints.
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Old May 18, 2015, 10:27 AM
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Thanks joe_crash! I'll be sure to check out blueskyRC. It's a long shot, but maybe they might be willing to help me cut some frames

-John
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Old May 18, 2015, 09:39 PM
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John what software are you using to design this? I would like to design my own, but I don't know what software to use...Google Sketchup maybe?
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