TEST: Happymodel Mantis 85

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INTRODUCTION

The Happymodel Mantis 85 represents a new input in the long list of micro brushless FPV racers. Happymodel is probably a new subdivision of Eachine/RealAcc. It’s at least a compagny working as OEM for major websellers. Here with the Mantis 85, we have a compact 85mm machine equiped of a F4 omnibus with a builtin OSD, some 6A BLheli_S/Dshot600 2S compatible 4-in-1 ESC board (up to 2S) and small 1102/9000Kv motors. For the FPV part, a super classic solution with a 600TVL CMOS 120 deg 48CH/25mW AIO combo. The Mantis 85 is sold in three BNF editions (FrSky D8 w/RSSI on last channel, FlySly AFHDS-2A and Specktrum DSM2/X) and one RTF adopting the FlySky AFHDS-2A solution coupled with a FS-i6 radio. One great argument for the Mantis is its price…Less than 140USD for a full RTF FPV racer … no so bad isn’it ?. Let’s discover this new proposal.

BOX CONTENT

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+ 1 x Happymodel Mantis 85
+ 1 x 2S 400mAh/40C with JST connector
+ 1 x Transmitter FlySky FS-i6 (using 4xAA batteries not included)
+ 4 x Spare props (2 CW, 2 CCW)
+ 1 x Allen key
+ 2 x Rubber bands
+ 2 x velcro straps
+ 6 x Spare hexscrews
+ 1 x Instruction manual (English)

A small bag with the accesories

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OVERVIEW

Let’s check first the main caracteristics of the Mantis: F4 + builtin OSD board not so bad … More the builtin MCU are classic/old MPU6000 with SPI connection… and since there is no softmounting, it’s good news.. Paradoxally the new generation of gyros (working up to 32Khz) ICM 20608 is they are not softmounted will freak out the machine completly (see the SPCmaker 90/110NG catastrophic results)

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It’s confirmed to be a 85mm machine

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with 2mm real 3K carbon lower frame/arms structure

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while the upper is 1mm only linked with aluminimum standoff.

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-FRONT VIEW
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Or with the battery strapped below. Since the battery strap is very thing, it’s hard to keep a perfect horizontal position.

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-SIDE VIEW
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The microUSB port is perfectly available out of the box without requiring to remove props. In the rear side installed up side down, a small buzzer. A very important element for such compact machine.

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All the upper structure is widely open…. so latteral soldering jobs are not super protected from shocks and waters. It’s advise to cover all pads connexion with liquid electrical tape to secure a bit the electronic.

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-REAR VIEW
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Whatever the BNF receiver version you will grab, the 2.4G receiver will be installed in the rear section… with an easy access to the bind button. In the other hand, the 2.4G antenna can also be damaged by rear props. Try to installed it more vertically down to maximize the control range.

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To (re)bind the receiver to the transmitter, you will need to
i) keep the receiver bind pressed while powering the quad (you can use PC USB port, it’s more easy to do both simultaneously) then
ii) press & hold the radio bind button while turning on the radio.

With the flysky AFHD-2A protocol, no RSSI feedback. Only the FrSky solution has.

-UPPER VIEW
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When the receiver is bound, a solid blue light is here.

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-BOTTOM VIEW
The battery strap pre-installed is super thin and don’t secure very well the battery installation beneath

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-WEIGHT
More than 55g with the receiver and the battery strapped installed…

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A total weight of 79g … with the 2S LiPo. It’s light but not ultralight…. Paradoxally not so so far from model with 1104 motors and 3S compatible. Clearly it will impact negatively the general thrust performances.

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Motors and props

It’s not so usual to see 1102 motors instead of 1104. There are weaker in term of thust but lighter. Announced to be 9000Kv, they should be 3S compatible even if ESC are not.

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46mm triblade props 1935 props

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LiPo

A 2S 400mAh/30C LiPo with JST connector. Here is probably the weakest element of the bundle. As you will see in the demo video, the 30C discharge is overated… A huge massive voltrage drop > 1.5V can be observed under load … clearly unacceptable even after few cycles of charge/discharge, the performances improve a bit … The first mod is to install another 400mAh/500mAh model with a true strong discharge rate.

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FPV-Camera module

Another good news, the AIO camera is installed on an orientable molded camera support.

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The minimum angle is about +15degrees

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while the maximum can be set up to 40-45 degrees

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As many eachine AIO FPV combo, two buttons can be found and are very easy to access from the top part.

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The more front select the NTSC/PAL systems if long pressed (mirror image if short pressed) and the read one select the Vfreq is short pressed (inside the eight Vfreq in the current selected Vband) and cycle between the six Vbands if long pressed.

The complet list of supported channels

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Transmitter

The classic FlySky FS-i6 comes with the RTF bundle. Here we have three 2-way switches and one 3-way plus two rotative dials.

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The firmware is the old 1.1

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So unfortunatly only 6 channels can be controlled. If you want to control 10CH, you will need to update the builtin Firmware.

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The first top left 2-way switch arms/disarms the machine while the 3-way selects the flight mode: in upper position for acro, middle for angle (6-axis stabilized) and the down position for acro + airmode

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Maybe the order should a but different since to boot completly the radio, you need first all switches in upper position. In mean a beginner who forgot that can be in acro directly.

UNBOXING, ANALYSIS, CONFIGURATION AND DEMO FLIGHT

The RTF version comes pre-bound and first good news especially with a flysky cheap solution, the failsafe is working perfectly… the motors are stopped within the first second. That’s great. The F4 board is flashed with betaflight 3.2.0 and seems to (almost) perfectly tuned at least in term of receiver/ports/flight mode. OSD part is pre-configured but maybe some elements can be removed from screen. The receiver is connected via iBUS protocol via a serial link on the UART1. DShot 600 is here by default and board & gyro pushed up to 8Khz for a total CPU usage around 5%… I am pleased to see that for a cheap machine, at least they spent some time to optimize a bit the machine. PIDs are default one but you will see in practice they are working pretty well. One small regret… that there is no a seven channel available in order to control the buzzer from a switch. A work around is to assign the AUX1 initially for the arming to the buzzer… You will need to arm with the throttle stick.

Even before to take-off, the voltage reading don’t show perfectly 8.4V… so some voltage reading ajustement must be done… and as soon as you take off (from 55% of throttle), the buzzer start to emit and the voltage drop around and below 7V!!!! so we have a huge/massive voltage drop at least for the voltage reading. Even wih the full charged battery, the punchout are not impressive…. clearly a better battery is required…. even if I already said, the battery performances will improve a bit vs multiple charging processes. Actually, you peform flips and rolls but powerloop are really risky… In another hand, thanks to the F4 board and 8Khz the machine flies beautifully… In angle mode, almost no drift are observed versus time… despite the absence of any softmounting solution. In acro, it flies really well… even after a hard tun, no collapse.. or bounce back… Almost no jello are observed in the FPV feedback. The camera perfomances do the job, not among the best actually but no major problems with…. The FPV range is also pretty good for a 25mW model. 100m and more can be obtained. Since there is no correct voltage reading, it’s hard to understand when you reach the real LVC alarm… but IMHO, flight time are limited to 2min30 (max 3min)…. It’s short … too short IMHO. In term of durability, no major problem can be revealed…. even props can resist to moderate crashes.

CONCLUSIONS

Except the weak battery element, the Mantis 85mm is good machine well designed despite its agressive price. The F4 board do a fantastic job and even if it’s a monster powerfull acro machine, it’s a super fun machine to fly in acro. As soon as you will upgrade the battery, performances wil be boosted. One good point, the machine (in RTF edition) work flawless out of the box. You can charge your LiPo/AA batteries and go in the field and fly FPV !!! . No bad for a first entry FPV brushless micro racer product.

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PROS

+ Good flyer
+ Work flawless out of the box (no extra tuning required)
+ F4 w/ betaflightOSD
+ Working failsafe with the flysky receiver
+ Good instruction manual
+ Cheap RTF solution

CONS

– Weak battery with overated discharge rate
– 6A only 4-in-1 ESC board
– Battery voltage reading not accurate (need ajustement)
– 2min30 of flight time
– Underpowered machine for crazy acro flight applications
– Battery strap too thin to secure very well the battery beneath

This quadcopter have been courtesy provided by Banggood in order to make a fair and not biased review. I would like to thank them for this attitude.
You can find it actually for 137USD at https://www.banggood.com/Happymodel-Mantis85-85mm-FPV-Racing-Drone-RTF-w-Supers_F4-6A-BLHELI_S-5_8G-25MW-48CH-600TVL-p-1221699.html

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