Frames

The Ov3rQuad

October 8, 20122 Comments

Out of almost nowhere, an opportunity to be one of the first to try a new frame design by Ov3rmind fell into my lap.  Ov3rmind, with help from Johnnycat500, describes the frame as “Open Source FPV Frame for all.  Inspired by numerous DJI arm-based conversion kits.” I’ll agree that it does share some features from a few of the popular frames around today. Similar to the TBS Discovery, the HT-FPV, and the QAV500, the frame is a simple asymmetrical design. It uses DJI flamewheeel 450/550 arms.

One major difference in this design vs. the rest is the addition of two vertical supports that run parallel to each other down the middle of the frame.  The thinking here is rigidity.  When flying it you’ll notice this, combined with the stability due to it’s size.  It’s about 6 inches longer than my HT-FPV, but about the same width (see pic below).  I can’t help but compare it to the HT-FPV since that’s the frame I flew before building this one, and maybe it’s me, but I was never able to tune that frame so that it flew like I wanted.  I was still cursed with the dreaded tail wag that a lot of people have with that one.  But this is not about that one, it’s about the Ov3rQuad!

During my build, and you can see pics of all of it below, everything went together well.  The only thing that was a little weird was that there were things that fit really tight and after assembly I noticed that one arm would hover about 1cm off of the ground.  I loosened up everything and tried again.  Still did it.  Upon further testing, this can be blamed on the DJI and clone DJI arms, seems they aren’t all the same and this could happen.  That’s the bad news… the good news is that it makes no difference when they’re ALL off the ground!

Shortly after my build, I felt great about the maiden so I took it for a road trip.  It flew great in the high altitudes!  I think you can tell by the video that there is still some tuning to do, but wow is this quad a ton of fun to fly!  On our trip, which most of the video is from I accidentally recorded a few flights in 1080, so you’ll see a little jello, but at 720 it’s non-existent, and I’ll get it that way on 1080 too with some tuning and balancing.

So yeah, it flies great, but how’s it crash?  Well, I had a couple of piloting errors and radio foibles where I found out.  The most extreme was a radio cut-out as I had JUST flown over a creek.  Lucky!  When I lost it, I was about a weak failsafe probably cushioned the impact a bit, but I didn’t even break a prop on that one.  Dusted it off and flew some more.  I know that JohnnyCat500 had a break of the G10 near one of the arm on the top plate.  As this is “open source” it’s ever evolving, he’s since strengthened the frame there, but I have the version that might have that problem (or maybe not, who knows?).

My build consisted of:

FC: OpenPilot CC3D
ESC: RCTimer 30 (flashed with SimonK)
Motors: Sunnysky 2212-13 980kv
Batt: 3S 4000Mah nano-tech
Props: I’ve flown with 9″ tri-props from himodel.com and 9″ gemfans — both great!
FPV Stuff: Maineiack 1.3GHz CL/SP/Crosshair, Sony 600TVL Super HAD FPV cam
Video: GoPro 2 on 720p/60

Seems it was common practice to give Ov3rQuad builds a nickname.  Because of the black and blue color scheme, I went with “The Bruiser.”  Seemed appropriate.

To sum it all up this is a great frame!  I highly recommend it.  It’s a great frame that flies like you think it should.  For further reading, there’s a HUGE thread about this frame over on the OpenPilot Forum.  If you’ve heard enough, and you want one for your very own, then order one!

TBS Discovery

October 5, 20120 Comments

Well I ordered my TBS Discovery back in late July and I finally received it a few weeks ago. The demand for the Disco is so high and it takes a while to get it (at least for me it did). And after I opened the box I realized the reason for the high demand. This frame is VERY well built and thought out. And assembly was very easy too! I had a few screws missing from my order, but a quick email to Trappy at TBS solved that – they’re sending the extra hardware free of charge.

To me, the icing on the cake for this copter would have to be the TBS Core. I’ve always flown 4S and when I got into FPV that posed a slight problem because FPV equipment runs off of 12V or 5V and the 14.8V+ from my 4S LiPo’s would most certainly fry them, so I resorted to running a separate 3S battery. In no way did it ever keep me grounded, but it certainly was a thorn in the side – having to deal with the extra batteries, charging them, dealing with excess weight, another thing to plug in and slap a LiPo alarm to, blah! No thank you. With the Core all I have to do is solder a few jumpers (once) and plug in the battery and GO! AND… I now have OSD (On Screen Display). The Core only informs you of battery voltage, current, mAh used, RSSI, and flight time – and really when you’re flying a multicopter, you don’t need anything else.

Here are my built pictures showing each step I took in assembly. I’m very pleased with this quad and I know its going to be my no. 1 quad for a long, long time.

Got DJI arms? Let’s save your motors!

September 12, 20122 Comments

Alright. This post is really for anyone who is a multicopter pilot, but its focused specifically toward those who fly with the affordable and available DJI arms.

As most of us know, the DJI arms seem to break easily and it’s my opinion that they were designed to break that way. Upon impact with the ground post pilot error or mechanical foul up I’m sure I’m not the only one would would want my most expensive items on board to remain intact while the other cheaper items take the brunt of the asphalt assault. After all, I’d rather my $4 DJI arms take the hit and break off than my $75 TBS Discovery frame!

So, to the point of this post, these arms we are using are not alone when they take a hit, they obviously have motors bolted to them, and most times they contain the ESCs, and sometimes a few other gadgets. Now if you do a Google search for “DJI arms crash” you’ll find several images of broken arms from the result of a crash and nearly 100% of the time the arm will break in 1 of 2 spots.

Most often is at the very end of the arm just before the motor. And, again, most of the time people will ziptie their motor leads to the other side of that break… showing here:

And as you can see, the leads for the motor have been ripped out – leaving this person with a worthless DJI motor. So what I suggest is to zip-tie those motor leads to the outer most part of the leg and use 3.5mm bullet connectors so in the unlikely event that we’ll crash, that part of the arm will break off, taking the motor and zip-tied leads with it, and “hopefully” the bullet connectors will do their job and allow the leads to slip out once they are pulled on. Illustration:

So, anywho, that’s my little tip. I hope it helps.

 

Building the DJI 550 Flame Wheel Hex with NAZA-M and GPS

September 3, 20120 Comments

With most of the parts finally delivered, my DJI 550 Flame Wheel hex build has begun. There is something very gratifying about having all the necessary components spread out on your work bench before assembly commences. Before I did anything I spent a great amount of time doing research and probably spent more money than I needed to but in my opinion this hex will be made up from “the right stuff”.

The frame is a DJI product and is made from high-quality components. The 550 Flame Wheel is nearly indestructible and based on the way I usually “fly” that feature will surely come in handy.

The ESCs are Hobby King 20 amp UBEC flashed with SimonK firmware and soldered directly to the bottom frame plate. The 550 Flame Wheel bottom plate has circuit board traces built in resulting in tidy wiring. I trimmed the ESC wires to the exact length required in an effort to keep the total weight down and also making for a cleaner appearance. The signal wires are braided wherever possible to avoid unnecessary RF noise which could potentially interfere with control system, video transmission, and GPS module.

Once assembled the frame has very little flex which is an important factor as I will be flying with 6 powerful 900kv 210 watt Tiger Motors. Each of the high-strength polymer arms are held in place by 6 aircraft-quality hex screws. The Dragon Link long-range system which will eventually be installed down the road.

Initially I had purchased six custom made G-10 landing gear legs which bolt directly below the motors without needing to drill any holes. It sure makes the hex mean looking!

The 6 landing gear legs have since been replaced with AeroXCraft’s fantastic DJI 550 landing gear and GoPro gimbal which attaches to the frame using existing holes. This lightweight landing gear is very well designed and allows for super easy CG balancing by sliding the battery carrier and gimbal back and forth on black anodized aluminum rails. Assembly took a couple of hours but I can’t say enough about how clear the included instruction booklet is. This is certainly a well thought out product.

I assembled the AeroXCraft 2-axis camera gimbal with HiTek high-speed metal gear mini-servos. Both axises rotate on flanged bearings and is super smooth. Rubber grommets hold the G-10 gimbal in place on aluminum rail mounts and combined with the foam padded lining on the inside of the camera box, the camera gimbal should dramatically reduce in-flight video “jello”. Again, assembly took some time but the included instruction booklet is excellent.

My mini FPV camera is placed directly above it between the mounting rails.

FPV is transmitted using a 900mHz 500mW transmitter mounted directly below the propeller tip on one of the arms for optimal cooling as video transmitters typically generate a fair amount of heat. To avoid RF interference, an in-line low-pass filter is installed where the antenna comes out of the transmitter.

The 900mHz dipole antenna for video transmission is mounted below the lipo battery carrier keeping it well away from the GPS module, thus reducing the potential for GPS interference.

The on-screen display is handled by an early version of the EasyOSD which is mounted on a different arm. The EasyOSD comes with a small GPS antenna (not plugged in here) which gives compass headings in the display but I haven’t tested it yet to see if it will interfere with the NAZA GPS module.

EasyOSD’s in-line current monitor module is conveniently mounted behind the battery carrier.

The NAZA GPS module comes with upper and lower aluminum mounting brackets and a CF post. There are several ways to assemble the GPS post including epoxy glues and velcro but it is important to retain the ability to rotate the module for slight magnetic declination adjustments based on where on the planet you might find yourself flying. I chose to drill and tap 2 set screw holes in each bracket (top and bottom) which do a great job of holding the CF post in place yet still allows for any adjustments if needed. I mounted the GPS module as far away from the camera gimbal as possible because it is known that GoPro cameras are guilty of being super noisy when it comes to RF interference. At some point in the near future I may look into building a thin copper-clad G-10 lining around the GoPro to shield any potential RF interference leaks.

The all-important NAZA V-SEN unit with built-in BEC and status LED is temporarily mounted on the back of the battery carrier. I intend to mount it in a more unobstructed area where it can easily be viewed from the ground no matter what direction the hex is flying. The V-SEN unit also has a USB port which enables programming by the Assistant Software I installed on a cheap little PC notebook.

And finally, the heartbeat of the beast: the NAZA-M flight controller. It is mounted in the center of the frame as close to the CG as possible. This unfortunately makes access to the ports a bit tedious but with long-nose pliers the job gets done. It certainly is well protected in there!

One of the early flights after the GPS module was installed. The hex did a pretty darn good job at pirouetting during an altitude hold, all without any fine tuning! Needless to say I was pretty impressed. Now for the fun stuff: tweaking! Stay tuned…

New frame coming soon from Team-BlackSheep

July 20, 20120 Comments

From the makers of the Discovery frame (Team-BlackSheep) There should be a prototype coming in a few weeks according to Trappy’s post here on FPVlab.com.

This frame should address many of the issues people have with the Discovery, including the tune-ability of an asymmetric frame, and a possible fix to the vibrations that the arms seem to attenuate.

I was saving up for a Discovery frame, but now that I see this post, I’m gonna have to wait at least to see what they are talking about.

And according to Trappy’s post here, again on FPVlab.com, he considers the frame complete and not in need of any modifications or updates. So that tells me that this new prototype is not an updated Discovery frame like I originally assumed, but an entirely new frame design. But who really knows. We’ll just have to wait and see. Here are some more shots of the beautiful TBS Discovery:

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