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Old 12-05-2020, 07:18 PM   #1 (permalink)
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Join Date: May 2006
Default My Awesome Oxy 5 (build report)

This build has been a long time coming. I know some of you thought I was unhappy with the build and gave up on it. That could not be further from the truth.

The truth is, I savor the build. I love it from beginning to end and I especially enjoy the wiring. It's the part that you can be a bit creative with, rather than just following the manual. With Covid rearing it's ugly head and no end in sight, I was just not in the right frame of mind to enjoy the build. It's not like I intentionally said I was going to stop, I just never got around to continuing.

Now with multiple vaccines on the horizon with a viable end in sight, and a week off for Thanksgiving, I was in the right frame of mind to continue. I'm still feeling horrible for the people who have lost family and friends, but in my little corner of the world, my outlook has improved.

Heli/Component Selection
What better way to pick a heli and components than listen to the good people of Helifreak. I was looking for a great one battery heli. I wanted to familiarize myself some different manufacturers so this was a chance to bring in lots of change. I posted the question:

Which "one battery" heli should I buy by accident?

After some great input we settled on the following:

SPM 4651T Receiver
I also switched out the DX8 for a DX9 black edition.

Build Goals
My goals when building (Resurrected from a previous build thread)
Component placement is always critical for me so I built off of all the lessons I have learned from previous builds as well as lots of Helifreak input. Here are the rules I generally try to balance while laying out components.

1) Isolate high current noisy components (main battery, ESC, and motor) from low current parts (antenna, battery, gyro, gyro controller, and receiver)
2) Protect all components from crash damage
3) Make heli parts you replace regularly easy to replace (Bottom Plate, Tail boom, belt, tail pulleys, etc)
4) Keep wiring runs relatively short
5) Protect all wiring
6) Allow the motor to be easily disconnected

For this particular build, it was quite easy to follow these with the stock design. The only area I did deviate a little on was I didn't shorten any servo runs. I opted to fold over the excess wire length under the sheathing rather than crimp on new connectors. I did shorten the sat wire since I decided on a placement that required a very short run.

Full size pictures are here if you want more detail:

Chapter 1 Mechanical Build
First thing I noticed was that the heli parts were very well packed. All boxes were well marked and all bags made logical sense and have clear markings. There was no paper manual included but I was able print the online manual, and since it was on-line I was confident that it was right up to date. The manual is well written and contained lots of detail and suggestions for configurations.

The Tail
The tail build went relatively smoothly. I did have some initial problems with the tail slider binding, but Helifreaks were quick to suggest the trick to getting a smooth tail (the ifheli slider adjustment) and it ended up sliding like butter.

I don't, however, love the tail design. If you land a little hard and bust that tail fin you'll have to rebuild the tail. I was tempted to cut off the stock stabilizer and mill a new one that bolts on, but I left it stock for now.

The Boom
On to building the boom. I love the square boom that alleviates the need for boom supports. KISS is strong with this heli. I also found it to be a nice touch that they provided a little plastic insert to put in the heli side of the boom to keep the belt from twisting prior to the boom being installed.

My one nit about the manual is that the black lines that are used to show which hole a screw goes in are sometimes hard to pick out when they are on top of the cross hatched depiction of carbon fiber parts. Case in point is page 20 upper right where they show you the hole for the canopy mount. I initially thought it was pointing to the middle hole in the row of three on top, not realizing yet they were the servo mounting holes. It's actually the hole way off to the left. Worse yet, If you bought mini servos, this is the point where the manual could have said “STOP AND REPLACE THIS WITH THE MINI MOUNTS”. Mine does now.

Bearing Blocks
I did have a little trouble getting the 3 bearing blocks in perfect alignment. It takes some finesse and I left it at “good enough” rather than working really hard to get the shaft to just drop though. Here is the thread I started on the subject:

Page 21: I did end up modding the slider holes on the bottom bearing block just a little as I outline in my manual, but it's been so long now I can't really remember if that was necessary. Don't do it unless you find it necessary. I do know I took advantage of the slide to make it easier to install the main gear and set the bottom bearing placement without shimming.

Page 24: I did make some notes on this page hoping to alleviate confusion for people. Here are my notes in case it helps.

Chapter 2 Mechanical Build (Continued)
Boom Installation (This is where I started back in after a 9 month break. Happy Thanksgiving)
Nothing to note. Loosen the screws and it slides right in. It's easy to adjust belt tightness.

Main Gear
This went fine. Nothing worth mentioning and I like the belt system design.

Main Shaft

It said “The side have groove go into head”. I don't know about yours, but I didn't see any groove on my shaft. The side with the shorter distance from the hole to the end goes toward the head. This gives more clearance for the feathering shaft on top and more shaft into the bearing block on the bottom.

The Swash/Head
This, is a thing of beauty. It's solid as a rock. I can't wait to fly it. The included tool for centering the swash in its travel and leveling it during construction is awesome. Same tool serves a similar purpose for the tail slider. I love when heli manufacturers take the time to add a tool like this to simplify setup. It didn't stop me from using a swash leveler during final tuning, but it made initial setup painless.

I had some initial problems getting the links to line up, but they just went away when I took it apart and put it together again. Something had not seated correctly first time.

Page 38 and 39
Another manual nit. The pictures show the motor installed when motor installation does not happen till page 42. No biggie, I just like a sequence that hangs together.

Servo Installation
Solid as a rock for all four. No notes. Love it.

Motor installation
Again, solid as a rock and easily adjusted. Nice design. I just noticed they measured the distance for you to the top of the pinion. I didn't notice that while building and figured it out by hand.

Chapter 3: Electrical Build (My favorite part)

The Fan
The HobbyWing ESC comes with a fan. Interestingly enough, it comes with a J style connector rather than something that could get power directly from its self contained BEC. I considering running an extra wire clear down to the Brain but that would have tied up a slot and didn't seem to make much sense. Instead, I wired a j male slot connector into the BEC output lines. I'm not sure the fan is even necessary but I figured it would be too painful to have to wire in later. If I choose to not use the fan I can just unplug it.

The Motor
I considered hiding the motor wires, but I traditionally like to have an easy way to disable the motor while working on the heli. Shifting the wires out the left side proved to be an easy solution. They hang there fine when being used and any of them can easily be pulled out to keep it safe while working on the heli.

EDIT: Turns out there is a J connector tucked under the capacitors on the ESC so I did not have to add one.

The FBL Controller
I chose to place the Brain2 under the boom block since in was a convenient place to collect up all the connections and be able to hide the birds nest. I sheathed all the wires and and hid any excess wire under the sheathing. I chose to run them outside the heli mostly to assure clearance from the main gear and make them easily accessible for maintenance. Since the ESC used a single wire to bring the RPM signal down to the FBM unit, I took advantage of the unused power connections as a place to connect the anti-brownout capacitor. Once again, I'm not sure if it was need on this suite of hardware but it was easy enough to be safe rather than sorry.

The Brain2 was very easy to configure. I missed that they didn't provide a hard copy of the manual or a printable version, but it was easy enough to get information from their configuration app. Here is a hard copy of the wiring diagram from page 4 if anyone cares.

EDIT: Another option, and a cleaner one would have been to combine the yellow RPM sensor and the Red/Brown BEC output on the same connector (even though they come separated). The capacitor could have remained alone on its own connector.

I initially configured it for my receiver wrong. The nice graphical selection screen drew my eyes to the the lower right knowing I had satellites, and then to the SRXL button to the right of them knowing I had telemetry too. I realized later that the catchall button with SRXL2 in it was actually the right choice off to the left.

The Receiver
Part of choosing where the Brain2 would go was choosing where the SRL2 receiver with telemetry would go. I put it directly over the boom where the existing cable would reach. None of these choices were that unique to me because looking at pictures most other builders made the same decisions on placement. I just had to put a J connector on one end to allow it to plug into the FBL unit.

I knew I wanted to get a nice 90 degree angle on the antennas and I didn't have anything on hand to do that so I milled a part to do the job. I'm pretty happy with how it turned out.

I agonized over whether to use two satellites or one and where to place them. I was tempted to put one toward the front of the heli, but going back to my guidelines, I hate to put receiver hardware near high current motor hardware. I considered lots of places down under the battery on the bottom tray but was not happy with the lack of symmetry with how they looked. I finally opted to just put one hanging down from the back 90 degrees delta from the main 2. It's more antennae congregated around one general location then I wanted, but I traditionally have not had receiver problems so I'm going to start like this. If I start having dropouts its easy enough to add a satellite or move this one. You can just barely see it in this picture hanging from the tail. You can see it better in the previous fan picture and the brain picture. In real life the antennae is further from the carbon fiber than it would appear here.

The Battery Tray
The battery trays are a thing of beauty. I had custom made slide in battery mounts for my Logo 600 running on 12S because it was two much of a pain tying down both batteries separately. Although I don't love the fact that the trays can't lay flat when out of the heli, I do love the way they snap into place. The procedure to install them perfectly aligns them and has worked flawlessly for me so far. If I ever shift to 12S they will even become more important, but I'm doubting I'll ever need to go that way.

I spent some time moving the battery around on the slide to get the center of balance (COB) correct. For those that have never done that, you hold the heli sideways by the head and let the main shaft serve as a balance point. You want it to not swing down on its own either on the head or tail side. Realize the OWB will keep it from turning one way so you have to flip the heli over and try both ways. You can see from the picture where my battery ended up.

The Canopy
I have to admit, I was not in love with the look of the canopy when I saw it in pictures. I'm pleased to say that the pictures did NOT do it justice. It is thinner than all my other cans because they have placed it just above the main gear. This give it a slimmer look and hopefully it will not make it noisier. The holes above the ESC are well placed and I'm pretty sure they will provide enough cooling that I probably would not even need the fan. The canopy goes on easily thanks to the front guides and the stock hold downs are easy to use. They have a little slop in them but I doubt that will ever be a problem.

Blade Installation went smoothly. The provided plastic shims were a nice touch if you have small rooted blades. I didn't need them on my main blades but did use the on the tail blades. They were a bit fiddly to install, but if you put the plastic shims in first then slipped the blades between them it was not difficult.

If you have never balanced blades before, Bob does a good job of explaining it here:

Final Swash Leveling
For the Oxy5, the anti rotation guide gets in the way of measuring the rear servo link. I chopped off a 10 mm Zip Tool just after the third hole to allow it to clear the bracket. With it like this, the tool can be used over or under the swash. I installed a screw in the third (outside) hole for use when measuring from the top, and a second screw in the first (inside) hole for use when measuring from the bottom. Sorry for the ESC fan noise. These videos show using it from under the swash and over the swash so that it can be leveled at both ends of it's range of travel. Watch the screw head as it is in line with each of the three servo connection points.

Swash Leveling videos for OXY5 from over and under the swash (10mm Tool):
RDLohr's Swash Leveling Zip Tool over swash on OXY5 (0 min 27 sec)

RDLohr's Swash Leveling Zip tool under the swash on OXY5 (0 min 45 sec)

Overall all, I really like the Oxy5 design. Other then the few minor gripes I have mentioned here, the overall design of the heli appears to not only be sound, but definitely a newer generation of design with solid function. I like it and can't wait to fly it. Given winter has set in in New England, that may be a while.

Hope you enjoyed this and hope I made someone else's build a bit easier with my ramblings.

If you like my build and want to see any of my other builds, check the links in my signature.
Thanks for reading!

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Last edited by rdlohr; 12-06-2020 at 09:48 PM..
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