My son and I are fairly new to FPV and have been flying for a few months with a GepRC smart35HD.  We've been having a blast and wanted to try our hand at building something from scratch.  What better way then to build a tiny whoop that we could use to play around in the yard, or in the house on rainy days/winter months.

After watching some videos and doing a little research we settled on replicating one of Dax's mobigital 7 builds that Nick Burns has also posted build info on.

The main idea is to build something from scratch and learn a more about how to setup/tune quads from scratch. I still need to order the Vista, but aside from that we have everything else.  

Components: 

• Mobula 7 v3 Frame
  
• Happymodel EX1102 10000kv motors
  
• HQ tri-blade props (40mm, 1.5mm shaft)
  
• Jhemcu GSF405A AIO flight controller
  
• Naked Vista (still need to order)
  
• Dax's canopy and camera mount (still need to print this)
  
• Tattu 2s 450mah batteries
  

I love a good whoop build.

If I can make a suggestion based on the components you already it will be to get a tooth pick frame instead of the cockroach whoop frame.

A few reasons for this are:

- The motor wires need to go through the frame / under the ducts and onto the board which after soldering will be a pain to swap fames
- The motor pads on that FC/AIO are fairly small and on the underside of the AIO board. A cockroach whoop frame will cramp the space around it making it uncomfortable to solder.

Based on my experience building a few quads I recommend that the first build anyone attempts is a 5" quad since there is plenty of room for routing wires and mounting components.

On micros we need to be very creative with the limited space and be mindful of the weight especially if we have dreams for fitting in a digital FPV system.

(07-Jul-2022, 06:53 AM)kafie1980 Wrote: If I can make a suggestion based on the components you already it will be to get a tooth pick frame instead of the cockroach whoop frame.

A few reasons for this are:

- The motor wires need to go through the frame / under the ducts and onto the board which after soldering will be a pain to swap fames  
- The motor pads on that FC/AIO are fairly small and on the underside of the AIO board. A cockroach whoop frame will cramp the space around it making it uncomfortable to solder.

Based on my experience building a few quads I recommend that the first build anyone attempts is a 5" quad since there is plenty of room for routing wires and mounting components.

On micros we need to be very creative with the limited space and be mindful of the weight especially if we have dreams for fitting in a digital FPV system.

I'm always open to suggestions!

Id love to build a 5" one day, but unfortunately we are in Canada.  I really don't see us moving out of the sub 250g category any time soon. The hoops we would have to jump through just to fly anything 250+ outweighs the fun we would have imo.  

I completely agree, building something bigger with more space to work on, for a first time build would probably be a wiser choice.  The problem is that both my son (10 years old) and I are going to be flying the tiny whoop.  For the safety of everyone in our house, and the drywall, we opted for a frame with prop guards. If you have a link to something that may be better suited, it would be greatly appreciated. 

To help make things easier to solder, I bought one of those little third hands with a magnifying glasses. I do have previous soldering experience, but I agree, this little tiny whoop is going to be a challenge.

Sounds like an interesting whoop build. I have been "eyeing" that JHEMCU GSF405
AIO board for a tiny build. I am anxious to see how it works out and what you think
about it.

(09-Jul-2022, 01:06 AM)iFly4rotors Wrote: Sounds like an interesting whoop build. I have been "eyeing" that JHEMCU GSF405
AIO board for a tiny build. I am anxious to see how it works out and what you think
about it.

Once we stop crashing and breaking the 3.5", ill be getting back to building this one  

I still need to order the naked vista but right now its not holding me up.  I can get the motor wires cut and soldered in place, the cap and battery wires run etc.  

Time is the only thing holding the build back currently.

The vista finally showed up for the tiny whoop build and I have some time tonight to get started on the build.

I have a couple "noob" questions for you guys:

1) Motor wires, how do you know which wire goes to which pad on the FC? My initial thought was it doesn't matter since there isn't any markings?
2)The vista didn't come with an antenna like I thought it would. I have some antenna's from a few external ELRS receiver's I bought, will these work?

The order of motor wires doesn't matter. Just connect them so the wires are all parallel / flat with none of them crossed over each other. Then if any of the motors aren't spinning in the correct direction use BLHeliSuite to reverse their direction, or if using Betaflight 4.3.x you can just use the motor mapping wizard in the configurator to do that.

The ELRS receiver antennas you have will be no use for the Vista because they are tuned for the 2.4GHz frequency and they won't be polarised. You need a 5.8GHz antenna that is LHCP polarised.

(03-Aug-2022, 02:55 AM)SnowLeopardFPV Wrote: The order of motor wires doesn't matter. Just connect them so the wires are all parallel / flat with none of them crossed over each other. Then if any of the motors aren't spinning in the correct direction use BLHeliSuite to reverse their direction, or if using Betaflight 4.3.x you can just use the motor mapping wizard in the configurator to do that.

The ELRS receiver antennas you have will be no use for the Vista because they are tuned for the 2.4GHz frequency and they won't be polarised. You need a 5.8GHz antenna that is LHCP polarised.

Ok, thanks Snow, I'll have to get an antenna ordered.  Is there any problem firing up the vista without one just to get everything setup and confirmed working?

Don’t ever power up a video transmitter without an antenna attached!

(03-Aug-2022, 03:44 AM)Lemonyleprosy Wrote: Don’t ever power up a video transmitter without an antenna attached!

Ok good to know!  What's the reason for this?

I'm also wondering if maybe I should power up this flight controller once I have the battery leads hooked up.  Make sure betaflight and ELRS flash ok before I worry about soldering in the motors/VTX.

Powering up the fc to test (without vtx) is a good idea.
Keep in mind you won’t hear any beeps with the motors unattached unless you wire in a buzzer.

Regarding powering up a vtx without an antenna: you’re generating a whole bunch of rf signal with nowhere to go except turn into heat. If I recall correctly the signal will basically flow to the point where the antenna should be and reflect back, creating standing waves. It’s a real good way to very quickly destroy a vtx.

If it’s not already, you should add “checking to make sure vtx antenna is attached and not visibly damaged” to your preflight safety and function checklist prior to each flight (or at least prior to the first flight of the day as well as after any hard landing or crash).

(03-Aug-2022, 04:08 AM)Lemonyleprosy Wrote: Powering up the fc to test (without vtx) is a good idea.
Keep in mind you won’t hear any beeps with the motors unattached unless you wire in a buzzer.

Regarding powering up a vtx without an antenna: you’re generating a whole bunch of rf signal with nowhere to go except turn into heat. If I recall correctly the signal will basically flow to the point where the antenna should be and reflect back, creating standing waves. It’s a real good way to very quickly destroy a vtx.

If it’s not already, you should add “checking to make sure vtx antenna is attached and not visibly damaged” to your preflight safety and function checklist prior to each flight (or at least prior to the first flight of the day as well as after any hard landing or crash).

Ok, thanks for the explanation, great info.  

I called it quits for tonight, but tomorrow I plan to wire in the motors.  I'll power up the FC, get ELRS and BF updated and if everything checks out, then wire in the VTX.

These little guys are tough to work on that's for sure.  I got the frame drilled out, spaced the FC where I wanted it and wired in the power leads/capacitor.  I also drilled a small hole in the back of the frame to hold the ELRS antenna.  Doesn't look like much but its a step in the right direction.

Tiny little whoops can definitely be tough to work on, sometimes you have to get creative. I do hope you’re enjoying the build though- I love building just as much as I love flying.

I see significant progress from your last pics.

One thing I should note that no one has really mentioned in any of the videos ive watched. I had to drill out the mounting holes in the Vista to get them to fit the M2 screws that Dax uses. I watched his video a few times and it looks like he did as well, but nothing has been mentioned of it.