Presenting the Riptide 5" Stretch!

This is an on going project to design a multipurpose quad for the 2017.

Frame Design goals:

• Light weight design
• X and stretch configurations
• Side/rear plates
• Modular arms
• Compact electronics stack
• Clean GoPro mounting solutions

Build goals:

• High power setup
• BLHeli_S 30A 6S ESCs to future proof
• Betaflight OSD use instead of MWOSD
• F4 FC

Summary:

My last design (the Shockwave) was great and satisfied my needs for the 2016 season. But there were a few more things for my next frame that I wanted, mainly a lighter design, and a smarter integration of my own custom PCBs. This is a clean and compact build, but that comes at the cost of less friendly maintenance. So far this has not proved to be huge issue, especially when every component is coated in liquid tape. The frame was centered around two components: the TBS Unify Pro V2 and the Omnibus F4 FC.

For questions on this frame, you can contact me at klee106@gmail . com. I will respond when I can.

PDB: Starting at the stack, there are two custom PCBs that I designed for this frame. The PDB (2oz copper) includes two spots for Pololu 1A regulators. I chose components that are all 5V compatible so both of these Pololu regulators are 5V 1A regs. I could have gone with 12V for the FPV components, but the TBS Unify Pro V2 (5V only) is extremely small and best of all, it has a flat bottom with solder pads on the sides! This takes us to the second custom PCB of the stack.

VTX/RX: The Unify Pro V2 has some really useful solder pads located on the sides. This allowed me to design a PCB that integrated the VTX and receiver on to one board to allow for a clean mounting solution.

Flight Controller: The Flip32 Omnibus F4 board with its integrated OSD is extremely useful. I've been using OSD for years now and they're a pain to set up and quite fragile. I chose this board over the later "pro" versions because I don't need the micro SD slot or current sensing. The SD slot adds height to the stack and I mainly fly 2 to 2.5 minutes a pack anyways. I might consider using the current sensing at a later point but for now, it's just not on the list of needs.

Back plate/LEDs: The back plate is one of my favorite aspects of this frame. I designed it to have serial addressable LEDs, a hard mounted XT60, and a VTX button extension. The XT60 is hard mounted to prevent the battery lead from getting cut up in the props. If the leads are rigid, they can't move. Thankfully the design of the frame also includes multiple zip tie points if a pigtail is used. One in the back and two on the bottom. There are also 4 extra zip tie slots located on the sides of the back plate to secure antenna tubes.

The VTX button is also an amazing feature! No more poking around with a driver to press the button. It allows the stack to remain buried inside the frame without worry. On top of that, SmartAudio is now live on Betaflight 3.1 so I can control the Unify with my OSD.
The last thing is that it has two extra holes on both sides of the SMA mount which are for the TBS Unify extensions. A 6mm M3 button head can be used to bolt the SMA connection to the back plate where it is secure and easy to remove.

Also hard mounting the XT60 has not failed so far. The XT60 is soldered to the back plate but still has wires which connect it to the PDB.

Top plate/GoPro Mount: The top plate has two carbon fiber parts to it: the top plate and the HD mount. The top plate is like a normal top plate. It includes slots that are spaced 0.5" from each other. I like to drill holes in my CreativeDex mounts and use bolts to secure them to the top of the frame. This is a much better way than using zip ties which break in crashes.
It also has another carbon fiber plate that is used to secure a seat for a GoPro. I liked this method better because it allows me to use cheap and durable GoPro mounts that my friends (Untitled3D) can print for me. There is also another TBS Unify mounting point on the end of the tail of the top plate with zip tie slots. This is to allow for vertical antenna mounting.
The tail was originally to help shield the antenna base from impacts. But the compact design also means that the antenna remains shielded from most direct impacts due to other things (arms, GoPro, props) sticking out farther than the antenna does. I have yet to do any noticeable damage to my Triumph. It hasn't even bent into the props during a crash.

Antenna Tubes: I was pretty tired of using zip ties to hold my antennas in place on my last design. It's ugly, fragile in crashes, and provides very little protection from your props. Instead on this frame, I added two holes on the top plate for the antenna tubes (I used Forever Tubes from Great 3D) to slide through. These tubes are secured to the back plate using 2 zip ties for each tube. By attaching the tubes to the back plate, I no longer have to worry about threading the antennas back into the tubes every time I remove the top plate. The top plate slides right off and easily goes right back on. Those tubes can also be heated up and bent to give it their "V" shape for better signal. Also having the GoPro sitting near those antenna tubes probably does add to their durability. They can't really get crushed in a crash. But we'll see when race season starts and the GoPro starts coming off more often.

Side Plates: Incorporating more side plates into a frame design does a few things. First, it increases the durability of the frame by providing lateral impact resistance. This means less bent standoffs and bolts in crashes. Second, it provides more protection for your components. There have been a few instances where some branches pulled a wire or two from inside my quad. By enclosing the stack on all sides, every component is now heavily protected. Last, I can add more LEDs to the quad if I choose to design a LED side plate like my last frame. Believe it or not, DRL wasn't the inspiration for that idea.

Arms: The modular design of this frame was to allow for a single fuselage design and multiple arm configurations. The 5" arm designs include a true X, stretch, and extended stretch configuration. The plane for 6" is to have only a true X and stretch configuration. With longer arms comes decreased durability so I would like to limit how stretched the quad is.
The slots on the tips of the arms are for the motor wires when the ESCs are bottom mounted. The little bump on the leading edge of the arm is to help with motor impacts which a majority of those happen in forward flight. The footprint around the motor is kept small because there is little that can be done to protect the motor bell from direct strikes.
Each arm also has a "hinge" around the stack bolt head. This is to allow for the arm to be removed without having to remove the bolts from the stack while still allowing for the bolt to add some support to the arm. Two more bolts are threaded through the bottom plate to hold the arm secure to the frame.

Bumpers/Motor Wire Protectors: There are currently two designs for bumpers for this frame. The first (1, 2, 3) includes a slot to allow for protection of the motor wires. The second is a partial bumper for when the optional arm braces are used. These don't have a motor wire slot because the bumpers would make the wires protrude out farther and expose them to danger. It is advised that for bottom mounted ESCs in this case, the motor wires are routed off the side of the arm (motor wires coming out of the motor facing the body like when top mounting the ESCs and then wrapping around the side of the arm to the bottom).
Each bumper requires an 8mm bolt instead of a 6mm one.