Quadmula DJInn F25 – sub 250g drone

It has been a long time since I built a new FPV drone. In fact more than 2 years. Why, you might ask: it is challenging with work, family, kids, other hobbies, laziness, you name it.

Than I saw a picture of the Quadmula Djinn F25 somewhere on Instagram and I loved how it looks like. I had immediately the idea to build a new sub 250g mini drone. Why less than 250g ?

The new EU drone regulations start from 1.1.2024 and all privately self-build drones above 250g, will be operated in the A3 category (which means not overfly uninvolved people and maintain a 150m horizontal distance from uninvolved people and urban areas). It is generally OK for most cases for free style flight, but sometimes it could be a challenge.

Therefore, if I manage to build a sub 250g drone with the Quadmula Djinn frame, I can operate from January 2024 in the A1 open category (“may fly over uninvolved people, but should be avoided when possible”). Scrolling through the product page of Quadmula Djinn F25 and checking the maximum take off weight (MTOW), the project seemed to be possible. I needed a day or two more to decide on all of the components, which I will be using for this new mini drone and then I was ready to do the order.

Parts List

  • Quadmula Djinn F25 frame
  • T-Motor F1404 3800kv
  • Aikon F7 Mini flight controller
  • Aikon 35A 4in1 ESC
  • DJI O3 Air Unit
  • HQProp DT63mmX5 Propeller
  • Tattu R-Line 4s 550mAh

The frame does not seem super expensive at first check, but when you start adding front bumpers, arm guards, O3 antenna mount, additional arms and DHL Express, the amount is quite significant. I ended paying 96.40$. Additionally, the frame was shipped from Taiwan, so I needed to pay import tax here in Germany, which were another 23 EUR. The frame was pretty expensive in the end.

Luckily, I had some old Aikon F7 mini flight controller and Aikon 35A 4in1 ESC (both 20x20mm), which I could use for this project. These are great quality, still working perfectly and support latest BetaFlight and BLHeli32. So at least I have saved some money on these parts.

Choosing the right motor was a bit of challenge, as I was not sure if I am gonna build a 4S or 6S setup (due to 250g weight limitation and battery availability). At the end I decided to go for a 4S 550mAh setup, as it was hard or very expensive to find 350mAh 6S batteries available. Therefore, I decided to buy the T-Motor F1404 3800kv version, instead of the 2900kv version. In combination with the 5-blade HQ prop, it would generate enough lift, so the drone will be powerful, but not too much.

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Around a week later after I have ordered everything, all parts arrived and I was ready to start the new build.

Frame Assembly

There is one thing, which I found extremely unacceptable with the Quadmula Djinn F25 frame – there was no assembly manual included. None! This is a No-Go for a frame, which is so expensive. I hope the Quadmula Team, have fixed this or if they read this article, they will fix it asap.

Here is an overview picture of the box and what was inside:

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My assembly manual for the Djinn

First mount the so called “Lock Plate” to the middle plate (the one with the integrated metal nuts) with the long screws (I think these were the M2x22).

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Then take the bottom plate (the shorter one) and mount the M2x25 7075 Standoffs. Attach the arms using M3 screws.

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The next step was quite challenging – putting the middle plate on top of the bottom plate and fixing the arms in the right direction and angle. This step took me I think like 5-10 minutes, because it was quite hard to fix the lock plate inside the arms´ holes. My advice: just be patient!

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As a next step you can attach the other standoffs: M3 in the middle and M2x20 in the rear part. Put some of the transparent tube on the M2 screws in the middle (I cut it too short, so please ignore my way of doing it).

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Mounting the DJI O3 Air Unit was quite easy and straight forward. Remove the air unit´s own bottom screws, so you can mount it to the frame with the longer ones supplied.

You are almost there, where you will need your soldering skills. Mount the 4 motors on the arms and put your 20×20 size 4in1 ESC (as explained I have used the Aikon 35A 6S ESC). Once all parts are fixed, cut the motor cables to the desired length and solder to the ESC pads accordingly.

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Last but not least, you will need to use the two TPU Side Plates for the DJI O3 camera as well as your flight controller / FC. Of course, you will need to connect the DJI O3 Air unit and the 4in1 ESC to the flight controller, but this is easy.

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If you have ordered the extra DJI O3 Antenna Mount, you will need to cut a bit the original plastic tube of the DJI antenna (the hard one, which protects the antenna cables) as it is too long for that small frame.

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The Quadmula Djinn F25 looks super cool and with a 4S 550mAh battery the total weight is about 228g. Here are some cool shots from outside:

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It flies pretty well on 4S and is super stable. I still need to do some tuning and outdoor flight tests, but overall it looks great for 2024 and all the new regulations coming into force.


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