Just as RedBull can't literally give you wings and make you fly, I'll admit that the Indestructible Goby 180 is not truly, 100%, literally indestructible. If you run this quad over with a car, hit it with a sledgehammer, or drop it in the ocean, it'll probably break and you can't really blame me for it. But crashing it normally - into trees, fences, the ground - it'll happily bounce back for more. Now with the marketing/legal disclaimer out of the way, I'll go in-depth on all the component, design, and build choices that I undertook to make the quad as indestructible as it can get.
I could go on and on about my personal experience on how many props I've broken or how many frames I've shattered to illustrated the importance of the reinforcements I did. But I'm only one person and therefore, one data point. So in the interest of not sounding like a self-serving asshole, I did a survey on pilots of the r/Multicopter community to see what other people break during crashes and what their experiences were. The promise of a chance to win free DAL props enticed 138 pilots to donate their time for science. In the chart below you can see what sort of damages are destroying people's hopes and dreams.
As you can see from above, props are unsurprisingly the #1 casualty, follow by antennas, VTX, motor, frame arms, and then to much smaller extent, smaller bits and pieces such as FPV cam and flight controllers.
As for component #3, I can't promise that my reinforcements will save your loss of dignity from bad crashes. But I can promise that your bank account (or wife/husband) will thank you for not throwing all your disposable income at those replacement parts. Here's how they work:
- "Unbreakable" DAL Props - These polycarbonate composite props are very well known in the RC community for their toughness. They have some flex in them so they can absorb most crashes. On bad crashes they will bend, but can be easily bent back. I still remember the days when everybody was still running those stiff but brittle GemFans and HQ props and sometimes breaking all 4 props in one crash. If you're were a high roller swinging HQ 5x4x3 props, that'll be $4 gone in the wind per crash.
- 3mm Carbon Top Plate - Most frames will come with 1.5mm or 2mm thick top plates, which should suffice for most people. However if you prefer landing Australia style - upside down that is - those thin top plates will eventually give out. The RMRC Goby 180 originally comes with a 1.5mm top plate, but I upgraded it to 3mm so you don't have to deal with this.
- Motor Protectors - The motors are usually the most expensive component. The Emax RS2205 retail for about $80 a set so protecting them with a $2 protector has more ROI than Apple stocks before Tim Cook took over. They also prevent dirt and sand getting into the motor bells. That's a win-win in my book.
- 8mm Aluminum Socket Screws - This is a minor point, but these are a bit longer and stronger than the standard 6mm button head screws you get in most frames. The extra length grabs the standoffs better and prevents them from bending. The larger diameter socket cap head is also way more resistant to stripping than the standard button head screws. Size matters yo.
- Battery Skid Plate - One thing that wasn't included in the survey but was pointed out by many participants was how often they damaged batteries during crashes - both physically denting them and getting it tossed around and chopped up by the props. This carbon battery skid plate + rubberized battery strap will hold the battery in place and prevent punctures in crashes. Just watch how the lipo survived multiple 40ft+ drops and slid across asphalt in this torture test.
- Protected RX Antenna - This is a tried and true ziptie + heatshrink tubing trick that gives the RX antenna the best reception and prevents it from getting chopped up by props during crashes. I painted it red here to, you know, make it go faster.
- 4mm Carbon Arms - I chose the RMRC Goby frame for this build mainly because of the compact yet sturdy 4mm bottom plate. The shorter 4in arms can already withstand much more stress than 5in arms. So beefing it up to 4mm thick makes me have the confidence to slap my "indestructible" sticker on it. From what I've gathered on the RCGroups thread on this frame, no one has managed to break the arms in a crash yet. But if you somehow manage to be the first to do that, RMRC, and by extension, I, will offer you a replacement bottom plate for free, and I will personally arrange a live AMA session for you on r/Multicopter titled "I crashed fast and hard enough to break a Goby 180 arm, AMA".
- Reinforced Molex connectors - This is another common build trick to protect those fragile pin-style connectors on the FPV and VTX. A little dab of hot glue will go a long way here. It's not visible in this picture but you can see it better here in a picture taken from the build blog.
- Angled Battery Connector - This is another build feature that was inspired by people getting their battery leads chopped up during crashes. I made it pointing down so it's away and safe from the props and easy to access for the bottom mounted battery. The copious amount of hot glue is also quite strong so it won't wear out like heat shrink tubes. The lead is also secured to the frame via ziptie so it actually has some wiggle room.
- Angled SMA Pigtail Connector - Besides props, this is statistically the 2nd most damaged part, due to fact that all the forces acting on the antenna are transferred to the solder joints of the SMA connector on the VTX. In the old days your $80 ImmersionRC VTX often looked like this. Then people got smarter and started to ziptie the antenna to the top plate like this. But it was a pain in the butt if you ever want to change out the antenna. So pig-tailed antenna connector like the Hawkeye or the Quanum Q48 I'm using here + the SMA thru-hole on the 3mm top plate probably provide the most robust solution I can think of.
- "Unbreakable" Foxeer Antenna - Once the SMA connector is reinforced, the strength of the antenna itself becomes even more important. The white "magic mushroom" antennas included in the Quanum VTX did not pass my crash testing, so I'm now using the much more robust Foxeer Antenna. The testing done here tell a pretty clear picture of how tough it is. I'm running the v2 version of the antenna, just as tough, but shinier.
- "Redshift Red" Paint - Everybody knows that red things go faster, as evident by the Redshift phenomenon of cosmological objects moving rapidly away from us, and the apparent increase in a bull's speed in the presence of a red-flag-waving matador. How does this make the quad more indestructible you ask? I dunno, maybe I'll make the next release purple.