A New Way to Fly, Part 2: Real Flight Test & Review

The Magic of Integrating the Camera, Gimbal, Goggles, Air Unit, and Flight Controller.

The interaction of these components is the key to the system's success. The camera in the gimbal provides the raw image. The Gimbal 3 stabilizes it in real-time. The Air Unit receives the stabilized image from the gimbal, compresses it, and sends it digitally to the Goggles L. At the same time, the Air Unit receives data from the aircraft's flight controller via the serial interface (UART). This data – such as flight attitude, speed, altitude, rate of climb, battery voltage, etc. – is processed and integrated into the image as an OSD overlay before it is sent to the goggles. The Goggles L receive the digital signal, decode it, and display the image including the OSD on the screens. The head tracking data is captured by the sensors in the Goggles L, transmitted back to the Air Unit via radio, which in turn forwards it to the Gimbal 3, which then pans the camera according to the head movement.

This architecture enables a highly integrated system where image stabilization, head movement control, and relevant flight data converge into a single, digital stream. The complexity of the individual components becomes virtually invisible to the pilot due to the seamless integration.

I tested this test platform in three worlds to put the Walksnail Gimbal 3 and the Goggles L through their paces under realistic and very different conditions. For this, I deliberately chose three different types of aircraft:

● The well-known MPX Twin Star (as a light trainer). This model is known for its docile flight characteristics, moderate speed, and low vibrations from the electric motors. An ideal platform for the first contact with the system, to assess the basic stabilization performance and head tracking in a calm environment and to test the installation on a simpler model, which results in a weight of 1.37kg.

● A large combustion engine machine (70cc engine, approx. 16 kg): The exact model is secondary here; what's important are the extreme conditions such a plane imposes on the technology. A 70cc gasoline engine generates significant vibrations over a wide RPM range, placing high demands on the gimbal mechanics and stabilization algorithms. Are there perhaps areas of natural frequencies that the gimbal cannot compensate for? Due to the high weight and inertia of the model, the pilot often has to secure the flight path in all directions. Here it will be seen whether the gimbal can deliver a steady image even under adverse conditions and how the system behaves in such a model. The sheer size also offers an impressive FPV perspective.

● Finally, the new variant of the TwinStar, the vertically launching TriStar, the VTOL variant (Vertical Take-Off and Landing) with a weight of 1.56kg. A VTOL combines the characteristics of a multicopter in hover with those of a fixed-wing model in forward flight. This places special demands on the image orientation, as the model has completely different visibility requirements in hover compared to horizontal flight. Head tracking in hover to look around, during landing to ensure the model does not pose a danger to anyone. Or in fast flight, for example, to properly assess the flight corridor or to keep another model that one is following in view, are some particularly interesting use cases.

The FPV platform fits perfectly on the TwinStar as if it were designed for this task.

Similar Installation with Detail Differences

The installation of the test platform with the gimbal and the Air Unit was principally similar on all platforms, but differed greatly in detail. It was easiest on the Twin Star. The platform was mounted on the nose instead of the canopy, so the Air Unit always gets enough cooling. Cooling is a general problem with all digital Air Units, not just from Walksnail; there is now also a fan that should really always be installed. Without airflow, the unit would otherwise heat up to over 100°C! In my case, with electric models, the power supply was always via the balance connector of the flight battery. 

The small size and the low system weight of the platform are not a factor for the flight performance on any of the models. With the combustion engine machine, the challenge was significantly greater. The 70cc engine generates vibrations that are transmitted directly to the fuselage. A careful selection of the mounting location for the gimbal is crucial, but since the test model has no cabin, I chose a rather unfavorable position on the fuselage in the propeller wash. The Air Unit is mounted vibration-dampened in the design. To simulate the worst-case scenario, no further damping was installed. The power supply in the combustion model is provided by a separate small LiPo to minimize interference from the engine's ignition. The weight of the system with the additional battery was hardly noticeable on a 16 kg model.

The VTOL would have been its own challenge, as the gimbal should be mounted so that it has a clear view in both hover and horizontal flight. This required positioning it on the nose, which must simultaneously ensure the view in hover as well as in horizontal flight. However, attaching the platform was very easy, as the TriStar has the same fuselage as the trainer. The vibrations here are moderate and not comparable to the combustion engine. The rapid attitude changes that might be possible in drone mode could pose a special load for the gimbal.

The initial setup of the Goggles L and binding to the Air Unit went smoothly as is typical for Walksnail. An update to the latest software versions was not necessary; everything was already up to date. Calibrating the head tracking is a simple process carried out in the goggles: put on the goggles, look straight ahead in a relaxed manner, and start the calibration by quickly pressing the button next to the 5-way menu button three times. It is important to do this in the head position that you will later adopt in flight.

All test flights are again taking place at the airfield of the MFSV Ettlinger e.V., with its 200m runway and, even more importantly in this weather, the large, shade-providing, cooling oak trees.

Flight Test 1: Relaxed Circling with the Twin Star

The old Twin Star can be handed over to the element of air with a simple push and half throttle, even with the additional weight. The advantage of the gimbal became obvious in the very first turn. Whereas with a fixed camera the horizon would tilt in the display, with the Gimbal 3 it remained almost level in the image. The stabilization worked very effectively and delivered a smooth, stable picture, even in turbulence. It felt like looking out of the cockpit window of a large airplane. The light foam plane, in particular, is quickly thrown from left to right by turbulence, which sometimes makes an FPV flight with a rigidly mounted camera unpleasant.

Flyover of the 200m runway, while the gaze naturally wanders slowly from front to side.

The head tracking in the Twin Star was a revelation for relaxed flying. You could look around, view the landscape, without having to put the model itself into a different attitude. Especially in turns, it was helpful to direct the gaze into the turn to better estimate the radius. The gimbal's response to head movements was direct and precise, with no noticeable delay. You quickly forget that you are actually controlling a camera – it felt like naturally looking around.

The OSD provided all important data clearly in the image. The artificial horizon, speed, and climb/descent rate were clearly legible and did not obstruct the view. For a trainer, this data is useful, but perhaps not absolutely vital. Nevertheless, it is comfortable to have all the information at a glance.

Flight Test 2: FPV Experience with the Combustion Engine Machine

Here I was particularly curious to see how the gimbal would cope with the vibrations of the 70cc engine. Please try FPV first with small machines that you have mastered perfectly. A combustion engine model like this is significantly faster, and you might leave your flight zone just as quickly. Never fly without an additional person who can also intervene!

Due to the system design, the camera on the single-engine machine looks through the propeller arc and is hit with the full propeller wash. However, this is not a problem for the gimbal; it has enough power to overcome the wind resistance. The propeller artifacts in the image are very annoying at first, but after a few minutes, you get used to them. The model used has an onboard starter for emergencies.

After starting at idle, the gimbal doesn't manage to keep all vibrations away from the camera. There is still a noticeable shake, but it's no comparison to a camera without stabilization.

Takeoff of the large machine in FPV, the runway is clear and the hot sun doesn't interfere much with the view, only the propeller artifacts in front of the camera are a bit distracting.

This gets much better after applying throttle, and once the plane is in the air and I reduce the engine speed to 'cruise throttle,' the surprise was a positive one. The gimbal did an impressive job of compensating for the engine vibrations. The image was not quite as silky smooth as with the Twin Star, but the worst vibrations were effectively filtered out. Only at certain RPMs in the lower range did resonances occur, and a slight restlessness was visible in the image, but far less than I had feared.

In turns, you naturally look in the direction you want to steer, to see if the airspace there is 'clear.' Here is the MFSV Ettlingen field from above.

Flying the large machine via FPV was an incomparable experience. The view from the "cockpit" perspective, stable and with the ability to look around, created a deep sense of immersion. You had the feeling of actually sitting in this huge model. Head tracking was extremely useful here. During a flyover of the runway, I could simply turn my head to aim at the runway and check the alignment for the next approach. When flying slowly over objects on the ground, you could follow them with your gaze. The inertia of the large model was compensated for by the agility of the camera view.

The OSD on this model, which is normally only ever flown by line of sight, was not just a welcome addition, it is a MUST. The artificial horizon always provides clarity about the machine's true orientation, even in complex flight attitudes or during the landing approach while looking at the runway. The most important information on such a large bird is the speed, to hit the correct approach speed, and the climb/descent rate helped in assessing vertical performance or maintaining a descent. While landing the TwinStar is a simple matter, with such a large machine you really break a sweat; all the data in the OSD is important!

No more GPS sensor on the platform for speeds or position; it vibrated off. Unfortunately, the artificial horizon cannot be saved.

After several test approaches, the GPS sensor vibrated off the test platform, and I then flew without position data, sink rate, altitude, and speed. I had to land again without goggles and 'normally' by line of sight. The initial conclusion is very positive, and I will install the gimbal on a large machine again, but next time on a twin-engine one without having to look through a propeller.

Or you could build a small nacelle under a wing with a clear view forward; the small offset from the model's center doesn't matter in the air and during takeoff/landing. Additionally, during landing, you might be able to better see the distance between the ground and the landing gear from the side.

Flight Test 3: Overview with the TriStar VTOL

The TriStar took off vertically, and the gimbal immediately showed its strength in hover. While the model "stood" gently in the air, I could look around freely thanks to head tracking – looking down to see the take-off zone, looking to the side to spot obstacles. With an airplane, you have the 'advantage' of always flying in one direction, without major possible changes. A VTOL in hover is a multicopter, which can move in any direction at any time, and the wind tries to do the same. Here, the movable camera allows for a quick turn into the new direction of movement to always maintain an overview. The head is very much in motion until the transition to horizontal flight, which I thought would be an exciting thing.

The TriStar shortly after liftoff and hovering to the starting position before switching to vertical 'normal' flight.

But since the TriStar only pitches slightly during the transition without losing altitude, it was no real challenge for the stabilization. The front motors tilt from a vertical to a horizontal position, but without a significant change in attitude in the camera. In the goggles, you don't notice the switch at all, only the speed has increased. The gimbal precisely counters the movement and kept the image stable on the original point of alignment. In head tracking, the camera smoothly followed the movements desired by the pilot, regardless of the model's orientation, just like with the other models.

In horizontal flight, the system behaved similarly to the Twin Star, with very effective stabilization even at higher speeds and turning maneuvers. The ability to direct the gaze into the turn or to look at the ground below during a flyover was also of great advantage here for orientation and the feeling of flight. Head tracking allowed for quick glances in every direction, which is particularly useful with an agile model like the VTOL to quickly scan the surroundings.

Even when landed in tall grass, you still have an overview with head tracking to possibly take off again.

The OSD data became important again with the VTOL during landing. The exact speed, the climb/descent rate (especially in hover and during transition), and the artificial horizon, which shows the actual flight attitude (as opposed to the gimbal's camera orientation, which by design has nothing to do with the fuselage inclination), were indispensable information for a safe and precise landing. Unlike a gliding landing with the TwinStar.

I am dedicating a separate conclusion to head tracking as a new dimension of gimbal control, as it was one of the most formative features of this system for me. It is amazing how quickly you get used to simply directing your gaze to where you want to look, and especially where you want to fly. The integration with the Goggles L and the Gimbal 3 was excellent. The latency between head movement and camera reaction was minimal, which provided a very natural feeling. Only when you pan your gaze between objects in close proximity, for example when taxiing to take off through a fence gap, is a delay noticeable. A correct calibration of the orientation is crucial, but always easy to perform.

The sensitivity of the head tracking can be adjusted in the goggles, which is useful. Too high a sensitivity can lead to small head movements causing hectic camera pans, which can be irritating. A moderate setting, where a slight head turn causes a proportionally larger camera pan, proved to be ideal for me. However, this depends on whether you want to fly close to objects like trees or quietly enjoy the view from above.

The Possible Applications Are Diverse:

● Orientation: Looking around during the flight to explore the surroundings, look for landmarks, or check your position.

● Landing: Directing the gaze onto the runway, even if the model is laterally offset on approach or has a significant angle of attack.

● Monitoring: Keeping the gaze fixed on objects or areas when flying over them.

● Immersion: The feeling of actually sitting in the model and being able to look around freely enhances the flight experience enormously.

For scale models or larger fixed-wing models, where you often fly wide circles or cover longer distances, head tracking is a real game-changer. It is also extremely practical for VTOLs in hover. Only in very fast, agile maneuvers or aerobatics might it be more sensible to align the camera rigidly forward or to control it manually, as fast head movements combined with fast model movements can take some getting used to at first. I was told that my first FPV loops and rolls looked terrible, and the video confirms this.

The elements in the OSD can be individually selected in the FC's INAV menu and placed on the image.

The display of OSD data from the flight controller in the Walksnail image works reliably and offers a decisive added value, especially with more complex models or flights where precise information about the flight parameters is needed. The artificial horizon, speed, and climb/descent rate are just a few of the many data points that a modern flight controller can provide. The display in the Goggles L was clear, sharp, and can be individually positioned where you want it in the image, so that the data does not interfere with the main field of view but is immediately readable when needed. The Walksnail software allows for further customization of the displayed elements and their positioning in the goggles, so that every pilot can design their individual OSD.

For the scale pilot who needs to keep an eye on their approach speed, or the VTOL pilot controlling the vertical rate in hover, this data is indispensable. Even for the trainer pilot, who might be gaining their first experiences with FPV and flight controllers, the OSD provides valuable feedback on flight behavior or the currently active mode.

Conclusion and Outlook

The CaddxFPV Gimbal 3, in combination with the Goggles L and Avatar HD Kit V2, is more than just another FPV system – it is a step towards a more immersive, intuitive, and informative FPV flight experience, especially for fixed-wing models. The effective stabilization delivers a steady image that largely cancels out the model's flight movements. This reduces fatigue and significantly increases flight comfort.

For me, the head tracking is the highlight of the system. It gives FPV flying a new dimension of interaction and orientation that fully unfolds its benefits, especially with large models. I can also imagine it being very useful in sailplanes or in the hover flight of VTOLs. You feel less like a remote control pilot and more like the pilot in the cockpit.

The Goggles L are impressive with their good comfort, their simple, no-frills design, and the consistently excellent image quality of the Walksnail system. The integration of head tracking works flawlessly. Moreover, the price is currently unbeatable at $200, costing less than half of its 'big brother' at $460.

To do head tracking with the big brother, an additional gyro box and extra cables are required, and of course, due to the size, this no longer fits in the box.

The OSD integration from the flight controller is reliable and delivers all necessary flight data directly into the field of view, which significantly improves situational awareness and is essential for complex flight profiles or larger models.

Of course, there are also challenges. The installation of the gimbal requires care, especially on vibration-intensive platforms like combustion engine models (secure the GPS better). The additional weight and complexity of the system may need to be considered when designing the model. The advantages over a simple, fixed-mounted camera clearly outweigh this. For ambitious fixed-wing pilots, scale flyers, and VTOL enthusiasts looking for the ultimate FPV experience, the Walksnail Gimbal 3 together with the Goggles L offers an outstanding combination of image quality, stabilization, immersion through head tracking, and comprehensive flight data.

Who Is This System for?

The  CaddxFPV Gimbal 3 with Goggles L is aimed not only at the advanced FPV pilot and model flyer but at anyone seeking the best possible flight experience and willing to invest in high-quality technology.

In conjunction with an FC, it is ideal for scale flyers who want a realistic cockpit perspective, also for pilots of larger fixed-wing models where stabilization and OSD are advantageous, and for VTOL enthusiasts who want to fully utilize the versatility of their model in FPV.

For pure freestyle or racing pilots on multirotors, a gimbal is usually less relevant, but for all other areas of FPV flying with fixed-wing aircraft, this is a very exciting and promising development.

This system shows where FPV with fixed-wing models can evolve: away from the rigid nose camera, towards a dynamic, interactive view from the virtual cockpit that elevates the feeling of flying to a whole new level. I am excited to see what further innovations Walksnail will present in this area. Many are still waiting for the 3D goggles with 2 coupled cameras….

The age of stabilized, immersive FPV flying with fixed-wing models has only just truly begun.

Oliver