RC Aircraft

Pico Goblin FPV

Completed Model

Wanted to try to build the FT Nano Goblin, which is the Flite Test foamboard version of the Strix Nano Goblin FPV drone. However, I wanted something slightly smaller, and found in the forums people were printing the plans out at 75% size with good success. So I reduced the original plans to 75%, but then realized that this doesn't take into account the foamboard itself is still going to be 100% size, so I had to make some adjustments. When doing the fuselage cover, it didn't fit right, so looked and found other plans online and decided to just print out that. However, the size was off. Apparently I ended up printing it at like 66% size, not 75%. So I just figured it out and created the new cover that would work. This thing is really, really small - 50 cm wingspan. Since the foamboard size was going to affect the curvature of the wing airfoil, I didn't know if this thing would even fly. There is hardly enough room for all the hardware, the battery just fits in the canopy area diagonally, and as such doesn't require securing. There's no way to make it any smaller than this.

Was able to find a cheap video transmitter that would work with FPV goggles. I wanted to just have a standalone VTX and not have to run it through any sort of flight controller (there's no room for one anyhow). From the product page, it described it as being able to manually change the band/channel, which is what I would need to do to run it without a flight controller. After opening the package, it didn't come with any instructions on how to set the band/channel/wattage manually, so after searching, even the product website didn't have the information. Finally, after finding a product page on a Russian website, I was able to get the information I needed.

Tight Space Construction (4 images)

For attaching the camera and the antenna, I used some plastic card around the screw holes for reinforcement, since just the paper and foam is way too soft. For the first test flights, I decided to remove the antenna and just tape a weight of the same weight in place instead so if it crashed, it wouldn't destroy the foam where it was attached.

I have an ELRS receiver and a PWM module that I was thinking about using with this, but honestly, it doesn't make much sense to do so given how small the battery is, which means I have to run the VTX at it's lowest setting just so I can get a good five minutes or so of flight time. I'll save that for my next fixed wing FPV, the Heewing.

Pico Goblin 2.0

After finding out about the Tiny-Whoop VTX and Camera combos you can buy separately (see /rcair/microbat for details), I decided I wanted to use it in the Pico Goblin, and pull out the existing camera, VTX, and lollipop antenna to use in another plane. It's honestly too much transmitter power going to waste for this little "almost disposable" foam board plane that isn't using a flight controller or even an ELRS reciever, so it isn't meant to go all that far out anyhow. I found out by doing so, I was saving a whopping 18 grams of weight, and because of this, would require a bit more weight in the nose, so I just increased the battery size from 500mah to 700mah to make up the difference, resulting in longer flight times. I re-did the fuselage so now installing the camera/VTX/antenna was easier and I had way more room in the cockpit area.

I also added a 25v 1000uF electrolytic capacitor to reduce video noise. I also added a small heat sink to the back of the VTX as well as put some small holes on both sides of the cockpit to allow some cooling, as the board becomes too hot to touch on even the lowest setting of 25mW.

Camera, VTX, and antenna replacement (4 images)

I could probably git away with using the same 1306 motor and prop combo like I used in the Mini Chiroptera, which would lower the tail weight and allow the use of a 500mah battery again, but I really enjoy the speed of the 1507 on this thing.

Pretty Clouds

  • The Dreaded Two-Second Maiden
  • Second Try
  • Third Try
  • Fourth Try
  • Good Take-offs and Landings
  • FPV Flights
  • FPV Maiden
  • Prairie Hill
  • Dos Arboles Crash
  • Dos Arboles Windy
  • Pretty Clouds
  • Perfect Landing
  • Tree Gates
The maiden flight did not go so well. After watching the video, I determined I had the aileron rates set way too high. You can see I roll one way, then try to roll the other way to compensate, it over-rotates, I try to correct and over-rotate again, and then crash, all in the span of two seconds. Some hot glue was all that was necessary to repair it.
The second flight went better, but it was pitching down too much to be able to trim and fly it without crashing at the same time, so I had to bail early. Only slight damage again, just needed some more hot glue.
The third flight went even better, but still needed some elevator uptrim. It flew well, but the wind was gusting to around 20 mph, which was just too much for something this small to deal with. I was happy I was able to get it to fly without too much damage.
The next day it was calm out, so I decided to push it to see what it could do. The first crash in the video was from me losing plane orientation. The second was from me trying to do a roll, but didn't realize I had the rates so low. I open up the throttle close to full a little over halfway through the video. This thing is really fast. Amazingly it's still not completely dead, a bit more hot glue should give a few more flights. Can't wait to try this with FPV goggles.
A retention pond near the local tech school. Some Herons come here to feed, and I was lucky to be able to fly around a bit with a few of them.
The sun was already down, but I really wanted to try to fly this FPV for the first time. I knew that the CADDX cameras are amazing in low light, so I wasn't worried. My biggest concern was the transition between launching and putting on the FPV goggles. It was a little strange but I didn't crash, so was pretty happy to actually fly it around. I honestly had very little faith this thing would fly, much less FPV, given that I made the mistake of making it smaller that it was supposed to be. The hardest part was tracking it with my head while flying so I would get a good signal, since it has to be flying at a good clip to keep aloft, unlike a drone, which can slow down as needed.
The next FPV outing was in better light, before the sun went down. The transition to goggles was easier, however, I forgot to put the lanyard around my neck so it was on top of the thumbsticks as I was starting out which was completely messing me up, but I was able to finally get it out of the way without crashing. Got a bit too close to one of the trees, I definitely need to fly this in a larger area.
Was able to get out to Dos Arboles airfield. The first flight went well, however, I'm not sure if crashed because I lost battery power, or because there was a strong wind behind me. Without a flight controller I have no telemetry and so I don't know exactly what speed I'm going, which makes it interesting.
My next flight, as windy as it was, I was able to go the same amount of time and more, and land just fine, so I don't think it was the battery being underpowered. However, it was a different battery, so I could still have one that is starting to fail, I'll have to keep an eye out.
Started recording after I got the goggles on. There was a little wind so I didn't do anything too fancy. Sky was very pretty with the scattered clouds, was interesting to see the shadows they made on the ground below being higher up. I think I found the edge of the radio range; at one point I almost lost control when turning back.
Had to shoot through the trees a few times given this was the first time flying this plane where there was hardly any wind, allowing me better control.

Plans

Parts List

VTX Instructions

JMEMCU Tran-3016W Video Transmitter

Support 7-26V (2-6S) voltage input

Operating instructions: 1.Short press is to adjust the channel (corresponding to the blue light, 1-8, a total of 8 times); 2.Long press 2 seconds is to adjust the group (corresponding to the green light, A, B, E, F, R, a total of 5 times); 3.Long press for 5 seconds to adjust the power (corresponding to red light, 25,200,400,800,1600MW, 5 times); 4.Long press for more than 10 seconds is to open 11 prohibited USA channels; The default does not output prohibited USA channels: 5705, 5685, 5665, 5885, 5905, 5880, 5658, 5695, 5732, 5880, 5917

About the use of the keys (while referring to the frequency table in the later picture, the flight control needs to be configured with the JSON file we provide in order to achieve OSD tuning reference)

The new video transmitter comes with locked frequencies and bands! To unlock it, turn on the power, wait a few seconds until the video transmitter starts, briefly press the button (as for channel selection), release it, and then press and hold it for about 15 seconds until the red, blue, and green indicators light up simultaneously. After rebooting, the video transmitter will be fully unlocked!