HappyModel Larva X | In-depth Review
HappyModel has done it again. This impressive and quite surprising engineers’ work has exceeded all expectations set for such a small model. The design and performances are quite spectacular, both for indoor and outdoor flight. It’s appropriate for racing and freestyle, as most toothpicks are. Larva X toothpick is small but powerful.
Although the fact that it’s not real 5” craft competition, it can do most of the things one 5” can - only a grade lower. The average mass for this type of quads is 100g and Larva X is much lighter than that - with just 50g. This model comes in a few editions, and all of them are BNF, even with an external receiver. Larva X is unique because the feeling of flight is near identical to 5” crafts.
That feeling surpasses expectations one might have for such a tiny thing - and there’s no difference whether you’re inside or on the race track. It takes only a few minutes of flight for that “bigger craft” feeling to kick in.
In addition to being very practical for pack-and-go, they can withstand crashes with ease. And the best thing of all, because of their size, people think they’re toys so they don’t pay much attention to them. That means you’re free to fly this powerful quad without someone bothering you.
Larva X is 2.5” aircraft made of very light components. The colloquial term for them is “toothpicks”. It’s stable, agile, autonomous and maneuverable; and these are the components which make this possible:
- 100mm motor-to-motor width, 3mm thick, sturdy and robust carbon frame with thin bridged arms
- Crazybee F4 PRO V3 Whoop AIO style flight controller
- 10A 4-in-1 FC integrated ESC, with 4 3-pin motor connectors (1.25mm pitch picoblade)
- EX1103 7000KV brushed motors with 3-holes mount seat design (triangle)
- Runcam Nano 2 customized camera with 1/3” 2.1mm lens
- 25/200mW, 40 channels VTx – HappyModel Diamond VTX
- There are few receivers to choose from - FrSky D8, FrSky R-XSR, FrSky XM+, FlySky, DSM2/X, TBS Crossfire. The price of the model is different for different receiver, HQProp or Emax propellers
- 2S or 3S battery up to 450mAh
We’re testing the craft without an integrated receiver for this review, and as an external receiver, we got FrSky R-XSR.
Components and spare parts
The contents of the box consist of a ready-to-fly quad, pouch with spare propellers, camera canopy, spare screws and nuts, screwdriver and a small 1.5mm hex wrench as well as instructions for the quad and the receiver.
The propellers we got were HQProps and so was the same spare set. HappyModel packs them randomly so you may get different combinations of fitted and spare propellers (Avan Rush or HQProps, but no difference in perfs).
- FC: 9/10
- Frame: 9.5/10
- Motors: 7/10
- Cam: 10/10
- VTX: 8.5/10
- Canopy: 8/10
- Props: 10/10
- Features includes in the box: 10/10
- Flight characteristics: 9.5/10
Crazybee F4 PRO V3 flight controller supports BetaFlight OSD and contains integrated ESC 4-in-1, up to 10A for each motor on the connector. For 1103 7000KV motors, specs are more than enough to withstand the most advanced punches, flips, rolls, low-to-max throttle variations. Considering there’s no need for heavy low ESR electrolytic capacitors, the craft’s mass is significantly reduced by integrating SMD capacitors in the power supply.
100mm (motor-to-motor) carbon frame is quite robust, and, despite its long and thin design - like a toothpick (pun intended), it’s not easy to break it. Unlike other models and frame designs, considering the aircraft's mass, it's sturdy enough to withstand high-speed crashes, i.e. to absorb greater kinetic energy. Arms are bridged with lateral bypasses with two branches. The core of the frame is octagonal and it’s connected via main arm to the lateral side bridges. This system is perfect for absorbing kinetic energy while withstanding hard impact. It’s also efficient when it comes to vibration absorption which comes from motors at high RPMs.
Motor mounts are cut off on the edges so their elongated spikes keep motors safe during an unstable hard landing. When crashing, concentrated forces are being redistributed in 3 sections of each arm and the octagonal core then absorbs them. For a classic Whoop styled flight controller, mount is 2mm, 25x25 diamond hole. Motor mount is drilled for triangle-shaped seats fixed by three screws, but it’s possible to use other 1103 motors with 2 or 4 screws seats as well.
Motors which are already included are HappyModel EX1103 7000KV ones. They support 2S to 4S batteries and weigh 3.7g each. They’re quite good, quiet, efficient and cheap motors which are very well balanced and don’t vibrate too much. Considering their size and the material they’re made of, they are quite fragile, and so are the wires. The frame protects wires so it’s not easy to shatter them, but it’s very likely a small crash would tilt motors, and the reason is already mentioned three-screw system. Original propellers are high-quality and quite strong. Despite that, the screws on the motor seat can’t withstand the impact- the kinetic energy from the propellers which don’t end up breaking transfers to the seat. In the worst scenario - that can cause the whole seat to tilt.
The solution for that is to include motors with 4 screws and M2 thread, regardless of attempts to lower the quad mass. That would minimize the forces which affect directly to the seat, diverting them to the frame arm which wouldn’t suffer due to its design. The frame was already designed for that type of motors so the upgrade would be pretty painless.
The crafts FPV system is designed almost perfectly. HappyModel chose to install Runcam Nano 2 camera with top 1.3”, 2.1mm lens. That provides amazing FOV when flying, which is very useful for freestyle. The camera makes sure you have a reliable video feedback with minimal noise. The noise doesn't ruin the flight experience, despite 700TVL, which makes feedback quite pixelized.
WDR is pretty good, even when heading towards the Sun- the ground’s shadow is still visible. The light-to-dark transition is fast and efficient. Camera sharpness is high quality- that makes Runcam Nano 2 better than most of the others on the market. HappyModel uses a customized model of this camera- you can see that when you look at the back where the connector is. Latency is fairly low- and that goes for all Runcam cameras.
The camera is mounted to the canopy via central holes. The canopy is already built-in and it’s not just another 3D-printed TPU piece. Just like the other models, it’s made of moulded plastic. This makes the camera aesthetically pleasing. Despite that, the canopy base is not the strongest so that’s where it usually breaks in case of a harder impact.
That’s exactly why you get a spare one. You also have an option to order spare canopies from the HappyModel website. The camera is in the canopy itself and its edges protect the camera while crashing. It’s better to change the canopy instead of a camera, right?
The video transmitter is their Diamond VTX 5.8GHz. Its design is quite clever; it's triangle-shaped and mounted underneath the camera. The canopy which protects the camera also protects the transmitter. Small but powerful transmitter has the power of 25-200mW and its mass is just 3g.
Output resolution is 640x480 (VGA). In addition, it has a built-in DVR with image quality better than the prestigious goggles with integrated DVR-s. DVR's output is 1280x720px @25FPS in a compressed AVI format. It supports SD's up to 32Gb.
Diamond VTX also supports SmartAudio protocol so you can change VTx settings through OSD control. It supports frequencies up to 40 channels. The input voltage is from 4.8V to 5.5V and consumption from 250mA to 510mA. VTx's range is long and the pilot is most likely to outrun the radio signal rather than the video signal if they use SPI integrated receiver.
The noise is minimal, even tree branches aren't problematic for the signal penetration. The antenna has u.FL connector and it sticks out through the canopy holes- that's why it's of the utmost importance to be careful when removing the canopy.
You don't want to damage the connector, do you? This could have been designed so much better. For example, to design the canopy in a way you can secure the antenna. There is a danger of hitting the propeller blades when taking a sudden turn, and the reason is pigtail length.
On the other hand, the pigtail length makes the antenna elastic so it doesn't easily fall out of u.FL connector. This model upgraded by additional insulator TPU spacer printed which protects the frame controller from VTx heat. Previous versions didn’t have this component- it was advised to use foam between FC and VTx or to print included insulator TPU spacer. The quad we got (and every other quad on the market) already has the spacer included.
There are a few different choices for a receiver. Some are integrated into the FC, some are already connected and only need to be binded to the radio station. Although integrated SPI receivers don't weigh as much and use less space, this type of receivers has a shorter range than separate ones. FrSky R-XSR receiver (the one we got for a review), is already connected to FC and configured, so it only needs to be binded and the quad is ready to fly.
Antennas were already tied to a frame but you still have the option to connect the antennas to the zip-ties and protect them with heat shrink tubes. The best thing is- it already comes in a box as an option. Rx is connected via SBUS part to already prepared, inverted SBUS (IRX pad). Unfortunately, considering only two UART ports, there's no room to connect telemetry too via SmartPort which this Rx supports. One port is used for SmartAudioVTx and the other one for inverted Rx receiver. But, when it comes to toothpicks, does anyone really need telemetry?
For Larva X, HappyModel recommends a 2S or 3S long battery up to 450mAh with an XT30 connector. Battery is not included so you have to order it separately. Larva X is pretty fun to fly aircraft for which you'll need a lot of batteries. Why? Because the flight time is average and you'll definitely want more. While reviewing, it was shown that 3S 450mAh batteries are the best for performances. The battery mount is already set to the bottom of the frame.
It's advised not to remove the safety sticker- the foam underneath is adhesive on both sides so the battery will stick to it and you'll have trouble removing it. Battery strap is under the FC's bottom and the frame so it's a bit complicated to get it out, although there's really no need to do that. It's firm and durable, which is good because this model was designed to land on the battery itself. It's a bit too long so you should probably shorten it with scissors so its end wouldn't go near the propeller blades. USB port is on the bottom of the FC, but it's protected by a battery and event the hardest crash won't damage it.
- Propellers: EMAX AVAN Rush 2.5 or HQProp 2.5×2.5×3
- Canopy camera mount
- Flight controller: CrazyBee F4 AIO w/ ESC
- Camera: Runcam Nano 2
- VTx: HappyModel DiamondVTX
- Motors: EX1103 7000KV HappyModel (3 holes mount)
- Frame (with 3 mount motor holes included)
What makes Larva X special are the flight performances. It's very fast, locked in and agile in the air. It's maneuverable, with lesser centrifugal force when sharp-turning and inertia, which is quite important for a racing craft. On the other hand, due to the frame design, it's easy to perform advanced freestyle maneuvres and acrobatics.
After only a few minutes, it's hard to believe you're flying something so small. Larva X's performances are so similar so a 5“ quad you won't notice the difference if you're used to the latter. When talking about the Larva X's cons, one is exactly what makes it so interesting; the mass. Due to a lesser mass, it's not wind-resistant and it's wise not to fly if the weather forecast mentiones wind.
Great punch and launching can also be considered a con when indoor flying, due to a 3S battery. In those circumstances, it's better to use a 2S battery. Still, beginners will feel more secure when flying with a 2S because their quads won't end up shattered and propellerless after crashing into a nearby wall. For more experienced pilots, the 2S battery for Larva X is kind of meh. Flight time, when flying with 3S 450mAh battery, is above average, despite the battery's mass.
While testing, we realized one could slow hover this craft for up to 7 minutes. It's 4 minutes if the flight consisted of hard-core racing. Larva X, when it comes to flight experience, stands out among most 3“ models and 2.5“ ones of the same price range. This one might not spark hardcore race pilots' interest, but surely will entertain you when flying in the park and indoors in normal flight conditions.
Latest model revisions come with pre-installed BetaFlight firmware 4.04. PID settings are custom-tuned, seemingly for a 2S. If using a 3S, you need to do some work in PID gains and filtering to reach the craft's optimal performance.
450mAh 3S battery is too heavy for quad's size, and factory PID gains are terribly set up. If making shown below changes, you get a top-performance aircraft that is swift and dynamic- much better than factory preprogramed for a 2S on 1102 or 1103 motors.
When flying with 2S, throttle resolution is good, and that is usually the weak spot on other models' batteries. The control level is pretty nice so the factory settings don't need to be altered there. Considering the battery mass, it's possible to gently fly for up to 5 or 6 minutes.
Quality and construction
Although the frame is robust, sturdy and hard to break, all other components are exposed to impacts and damage.
The first component to take the toll is the canopy. Considering it's mounted to the FC stack on a thin base, it can easily break if crashing. Luckily, there's a spare one so you can replace it. Despite the aesthetics and quality, it's fragile when it comes to hard crashes.
Three basic screws that hold the complete stack including the canopy, are M2 and are made of metal, while the forth is plastic. On the plastic one is mounted the FC's front and it's much lighter than the other ones. Despite the choice of material, it doesn't interfere with stability and stack hardness. M2 nuts are plastic as well, but they're top-quality and don't really unscrew and fly away due to vibration.
While spinning after a crash, it's easy for the antenna to detach from the connector, which can be fatal for VTx- especially if it's set to 200mW. It's also possible for antenna top to get to propellers' area and that means they'll cut it from the pigtail.
Silicone grommets on which the whole mount stack is based are sturdy and good for filtrating high-frequency motor vibrations. Their height is well-calculated so they protect the USB connector inside of the frame. The connector, because of that protection, is not exposed to external conditions.
Battery strap's quality is also very good, but it's a bit too long so you should probably shorten it. After that, the strap does its job perfectly. Direct soldering on PCB is used for everything but motors so the soldering job is done a bit wonky for some wires. That doesn't mean the quality doesn't satisfy QC and QA standards, it just has a certain effect on the aesthetic. The perfect example of that is the soldering joint of the main battery connector.
When you order an external receiver, it's connected to a frame using a tie and a double-adhesive foam.
The main concern here is the antennas; they are tied to the frame but are prone to getting too close to propeller blades, which means the blades will badly damage them. It's advised to remove those ties, take the ones you got in the box separately, tie them to the frame, insert them with antennas into the thermal shrinking tube and shrink everything using heat.
You should do that in the middle of the bridge so the antennas can't reach the propellers' area.
Motors are silent, without substantial vibrations and oscillations. Because of their mass, they belong in a middle-class, but that also means the seats are quite fragile. When flying at a higher speed and crashing, this type of frame starts spinning. Propellers are hard and nothing will happen to them but, because of that, motors are at risk of damage. A good solution would be 4 screws in a mount, no matter the fact that that would make the quad heavier.
As their other models, Larva X also goes along with HappyModel philosophy: performance, agility, endurance, maneuverability, and efficiency- all together for a small price. More powerful motors, configurable VTx with built-in high-resolution DVR, top-quality camera and powerful ECSs are significant improvements when comparing to older models.
Larva X certainly holds its place in a toothpick world with its price range and quality. Considering the quality of VTx and camera feedback, it's better to get the external receiver model because it has a longer range than the model with the internal one. Naturally, the external receiver is a better choice for outdoor flying- the pilot has more freedom.
Larva X should be fun for experienced pilots who just want to fly without a lot of stress as well as for beginners who are entering the FPV world. The size makes it very practical for spur-of-the-moment flying, but despite it, you shouldn't be fooled by it. Toothpicks are much more powerful than they look like and can do more than you'd expect from such small crafts.
HappyModel has, with this model, proved they listen to their consumers and their demands and wishes. We believe Larva X is not their last top-quality model and we can expect something similar in the future.
Author: Davor Kustec