WIP Quadcopter

[Brazz]

I've had my Rostock Max V2 since late november. It was my first 3D printer and I have been dabbling in quadcoptery since mid-2013 (although I was deployed for most of 2014). Flash forward to yesterday when I reassembled my quadcopter with new parts that I printed myself and I can honestly say that I'm amazed at my printer. I've had maybe one bolt loosen since I assembled it at the beginning of December.

As for 3D printing quadcopters, I highly suggest including carbon fiber tubes in your arms. Makes for what I assume is a lighter part. Less you have to print at least!

You'll see my design here as a work in progress. I read Chunwe's long-flight quadcopter thread on rcgroups and decided it was time to take my old ideafly to the next level. Here you can see my freshly slapped together quadcopter with new 17" props, 490kv motors, and some 3d printed body parts and motor mounts that incorporate carbon fiber tubes from hobbyking. I'll be printing revisions to it throughout the next month and trimming all of those wires. You can see I'm taking the piece-by-piece approach to design instead of creating a frame from the ground up.

-Brazz

[img]http://i228.photobucket.com/albums/ee44/Brazzle88/Quadcopter/20150616_200652_zpsbrv7ojdi.jpg[/img]

[nrbelk]

That is pretty cool! I bought my printer (still assembling it) mainly to print parts and frames for quadcopters I want to tinker with (and also parts for a reef tank).

The first thing I plan to to is to try to print all the parts for a 350 or 400 size frame. I'll be using the Navio+ as well as a DJI motor kit thing.

[626Pilot]

490KV motors with 17" blades is an interesting choice. Nearly 4x as much sweep area as a 9" prop. I'm guessing that produces a lot more lift, and 490KV is more than enough rotational speed considering that. What's the useful payload?

[Jimustanguitar]

Nice looking quad! I'm working on a little one right now, and am thinking about a big one after that.

I've been at InfoComm this week (the tradeshow for the AV industry) and there are several large quads to oogle here. A lot of places just have Phantoms and painful looking knockoffs, but a few places have some interesting things to see. The biggest one I saw was from XFold, and it had 30" props and was tested to lift a 250lb payload!

[img]http://i.imgur.com/wtMqary.png[/img]
[img]http://i.imgur.com/4t007W7.png[/img]
[img]http://i.imgur.com/BP1bitt.png[/img]
[img]http://i.imgur.com/RWmmhwf.png[/img]

[Brazz]

@626: I'm staying in the gopro with stabilizing gimbal range of 1-2kg. When I had 10" props and 850 kv motors, I had approximately 8 minutes with a battery-less weight of 1.2kg. It didn't fly until 70+ percent throttle and when the motors heated up it would actually be closer to 85 which is almost unflyable. I want to do 20-30 minutes with a heavier camera on a 3d printed gimbal, so I figured step one was increasing my thrust-to-weight ratio.

@Jimustanguitar: at first I thought that first picture was your posting a pic of something you printed and I was like..... Thanks for the cool pics of quadcopters!

A progress note: I shortened up my ESC wires yesterday but have been having print-fails on my top and bottom plate (for the body). 1st print fail was a (I shit you not) a knot in the abs reel, which resulted in ghost printing and a messy ....(filament tensioner up top thingy). The 2nd was about 5am this morning (ie just now) finding that within the last 30 minutes of the 9 hour print the tube going down to the printer head had unscrewed under the tension and 10' of ABS was feeding onto my desk. So in the future, tighten that thing with more than your finger tips because it can result in "ghost print". That said....all fixable problems! (outside of random knots in ABS reels...)

[626Pilot]

Design of aircraft is so tricky. Anything you want more of is going to throw other things off. If you want more payload, you need more lift. If you need more lift, have to increase output somehow, which usually means bigger batteries, which means some of the payload you gained is gone. And then, to handle the extra weight, you have to use stiffer, heavier landing gear... etc. As they say, the five aerodynamic forces are thrust, lift, weight, drag, and money! There is even a fictitious currency talked about by pilots called an Aviation Monetary Unit, or AMU. 1 AMU = $1,000 US.

One thing I've noticed is that a lot of these UAVs are designed to be optimal for constant hovering, but never forward flight. Amazon's mockup is just a regular old quad copter with an underslung load. I wonder why they don't use a wing? However efficient the props and motors are, those things will be expected to fly miles through outside air at altitude. If they run into even a 5-knot headwind component, which they will (and worse) on a regular basis, it will require that much more energy consumption.

Why not a wing?

Moderately sized wings, with a lifting body design (where the fuselage itself generates lift), and an internal cargo bay. For lift, hover and landing, several ducted fans would be hidden in the wings. For forward flight, a couple of ducted fans would scoop air from the nose and expel it out the back. (Or, servos could be used to rotate the two rear fan themselves, or whatever.) The exhausts would be placed close to each other, so that single-engine operation would be more stable; in calm wind, it might do to cruise on only one. The internal frame would be carbon fiber, or perhaps something like Howard Huges' balsa composite. The wings and fuselage would be skinned with fabric, like the old Bellanca airplanes. This would be very lightweight, and polyester wing fabric is extremely durable. It will likely outlast the drone it's applied to.

Instead of dragging the payload through the wind and getting it covered in dead bugs, dirt and smog, they could have a cargo bay inside the fuselage. The cargo itself would be sitting on a shock-absorbing pallet. When the drone arrives, it uses servos or solenoids to detach the pallet, and it falls to the customer's lawn or front porch. The drone, with an empty cargo bay visible underneath, returns to the hangar.

Because the cargo is inside the aircraft, and because the whole frame is covered with airplane fabric rather than just a bunch of draggy stuff sticking out in the wind, and because the vehicle can fly forward like an airplane, I think it would be far more feasible for a delivery service. I don't see them making a more hat rack-looking design (typical quad copter) work unless they want to put little two-stroke gas engines in there. The environmental impact, and impossibility of operating a two-stroke engine in California (possibly other states), would make that rather burdensome.

[Polygonhell]

There are a few hybrid wing designs, but the transition in and out of hover is apparently difficult to manage and sticking a decent sized payload in it probably wouldn't help.
I tend to agree the Amazon design looks like a brute force solution, having said that if what I was told about there performance is accurate, they are a lot more capable than I would have predicted.
The benefit of the multi rotor design is simplicity and robustness, you can lose props and as long as you have enough power and more than 4 left in reasonable positions, the flight controller will usually accomodate.

[IMBoring25]

Yeah, their brute-force octocopter seems more about making news than making something that would work in more than a few very specialized cases.

My thought on the matter would be a hybrid airship operating on hot air, with two envelopes and a small on-board burner (or resistance heater) for fine buoyancy adjustments. Launch slightly heavier-than-air, fly to the destination, land. Vent the outer envelope (to a point slightly lighter-than-air when unladen) and drop the payload. When out of the drop zone, vent a little more air and return to base slightly heavier-than-air. I want royalties.

[626Pilot]

The transition between forward flight and hover probably has to do with slowing down for hovering in a controlled, reasonably quick manner, without having to coordinate a super awkward flare maneuver. (The other option is to simply cut aft thrust, and wait for the aircraft to start losing lift before activating the lift fans. That's harder to coordinate because it takes awhile to bleed off airspeed.)

A ducted fan design could accommodate the right maneuvers. Each of the fans would have a servo axis that will let it tilt from down-forward (for slowing down to hover), through down (hover), down-backwards (for accelerating from hover to level flight), and backwards (for level flight). The underside of the fuselage is recessed to allow the gimbals to rotate freely. The aircraft would then have thrust vectoring, and could transition between hovering and forward flight like a Harrier or an X-35. The landing struts would be fixed (non-retractable). This will dirty up the aerodynamics a little, helping us to slow down more quickly.

I want royalties, too.

[Jimustanguitar]

VTOL winged crafts are definitely the future of many drones. There are certainly applications for both, but the long haul and payload stuff has got to figure out how to add wings or they'll never have a useful range.

[teoman]

Or use a completely new technology of batteries. The aluminum based ones look promising.

[Polygonhell]

VTOL winged crafts are definitely the future of many drones. There are certainly applications for both, but the long haul and payload stuff has got to figure out how to add wings or they'll never have a useful range.

FWIW if the specs of the current prototypes that were conveyed to me second hand are accurate then the range is viable today with current battery technology.

[626Pilot]

VTOL winged crafts are definitely the future of many drones. There are certainly applications for both, but the long haul and payload stuff has got to figure out how to add wings or they'll never have a useful range.

FWIW if the specs of the current prototypes that were conveyed to me second hand are accurate then the range is viable today with current battery technology.

But is that a regular Li-Po battery, or some scary thing they only make 100 of a year and it's ten grand for five minutes of capacity? (Like all those $580 wrenches the gov't buys.)

[KAS]

(Like all those $580 wrenches the gov't buys.)

That's sorta sad and true to some extent. Snap-on actually gives us a 50% off MSRP discount with free shipping and obviously tax exempt. Probably why you'll mostly see that brand in the military.

[barry99705]

(Like all those $580 wrenches the gov't buys.)

That's sorta sad and true to some extent. Snap-on actually gives us a 50% off MSRP discount with free shipping and obviously tax exempt. Probably why you'll mostly see that brand in the military.

My unit stopped using snap-on. They wouldn't warrant their tools anymore. I've never seen a $500 wrench, but I have seen $500 springs the size of a quarter. The reason they cost so much is you can't buy them by themselves. You have to buy the whole handle assembly. Then it takes 5 minutes to pull it out of the new part and 5 minutes to put it in the existing handle. Or you can do what the manufacurer wants you to do and take the aircraft off the flight line for a day to replace the whole damn thing.

[KAS]

(Like all those $580 wrenches the gov't buys.)

That's sorta sad and true to some extent. Snap-on actually gives us a 50% off MSRP discount with free shipping and obviously tax exempt. Probably why you'll mostly see that brand in the military.

My unit stopped using snap-on. They wouldn't warrant their tools anymore. I've never seen a $500 wrench, but I have seen $500 springs the size of a quarter. The reason they cost so much is you can't buy them by themselves. You have to buy the whole handle assembly. Then it takes 5 minutes to pull it out of the new part and 5 minutes to put it in the existing handle. Or you can do what the manufacurer wants you to do and take the aircraft off the flight line for a day to replace the whole damn thing.

I do see that a lot in the AF. Everything is module based on the munitions side. They require us to remove and replace whole sections/modules of a component vs repairing it on site. Then we send it back to the manufacture for simple circuit repair, and get charged out the a$$ for it. We've never had an issue with Snap-on, but then again we don't typically see a person beating the pi$$ out of tools while working on live munitions.

[barry99705]

I do see that a lot in the AF. Everything is module based on the munitions side. They require us to remove and replace whole sections/modules of a component vs repairing it on site. Then we send it back to the manufacture for simple circuit repair, and get charged out the a$$ for it. We've never had an issue with Snap-on, but then again we don't typically see a person beating the pi$$ out of tools while working on live munitions.

I'll never forget the sound of a nitrogen tank for an AIM-9 bouncing down the flightline!

[Brazz]

Hey guys, here's an update. I love my Rostock Max V2 because I can leave it alone for 2 weeks with the glue still on the plate, fire it up, and print quadcopter parts. Here's my progress
[img]http://i228.photobucket.com/albums/ee44/Brazzle88/Quadcopter/20150929_162607_zps7kypwt4v.jpg[/img]

A little hint for those wanting to secure carbon fiber tubes (mine are square): you want to clamp them so make sure you design "clamping" into the specs. You'll notice the gaps in my body support towers.

Also, my leg design sucks and needs some redesigning. I'll post up when I have the new ones printed out.

-Brazz

[Khalid Khattak]

Dear please if you mention the total weight.

[Brazz]

Dear please if you mention the total weight.

Khalid, sorry that I don't have a proper means of giving an accurate craft weight. I only have a scale that reads accurately up to 1kg. Maybe I should get that hanging scale I've been meaning to buy from HobbyKing...

However, I modeled my design and specs off of the data that I gleamed from reading hundreds of pages of "long flight" quadcopter threads over on RCGroups. My ballpark weight with Gimbal, gopro, and 2x5200Mah 3S multistar batteries is 2.8 kg. The 17.5" props pared with either 490kv or 390kv work magic when pared with 3S and 4S batteries respectively. I went from having barely any thrust ratio to work with when flying with my gopro to flying with a gopro below %50 throttle and also being able to load a bit more payload onto the craft Screw buying 10" props on 850-1100 kv motors, or any quadcopter derived from that setup. Low KV motor and huge prop is the way to go....let's see if any manufacturers catch up in the years to come! (laughing at all the out-of-the-box quadcopters that are tiny) ((though I guess they're a bit easier to transport))