TBS GEMiNi

-

Letting the cat out of the bag 

The TBS GEMiNi is a small hexrotor that is meant for fpv racing. The frame is based on my Shrediquette GEMiNi that I developed in spring 2013. Team Blacksheep (Trappy, Riscyd and Perna) contacted me a while ago, and we started to modify the design in order to improve it further and to make it more user and crash friendly. After some information had already leaked before the offical release (may it be on purpose or not... ;-D), the new TBS GEMiNi has now been officially announced on fpvlab.com. This means that you can very soon buy the GEMiNi multicopter!

 

Features of the TBS GEMiNi

  • Forward-tilting motors for efficient, high speed flight
  • Built-in FPV camera (TBS ChipChip V2)
  • Optional HD camera (Mobius Action Cam)
  • CORE OSD/power supply with integrated current sensor
  • Ready for long range FPV
  • Custom 4A ESCs with SimonK firmware
  • Custom T-motors
  • 4" propellers
  • Motor distance: ca. 215 mm = 8.5"
  • Taulabs Quanton-based flight control
  • Crash-friendly, yet integrated layout
  • Top speed: About 90 km/h
  • Weight: About 340-370 g
  • Price: Less than 600 USD


The package includes the TBS Gemini main frame + plastic parts, a canopy for race and film, the motors /  ESCs / props, a flight control, a pre-configured CORE PNP25 (optionally upgrade to CORE PRO), a FPV camera, a TBS BOSS 5.8GHz (optionally upgrade to 2.4GHz), a 3S battery and a fancy carrying case. The GEMiNi can be ordered by end of august, and it will be shipped by late september.


What about the tilted propellers and the canopies?

On the GEMiNi hexrotor, the motors are tilted 10 degrees forward in order to decrease the angle of attack of the copters body in forward flight, which decreases the net aerodynamic drag in fast translational flight. Additionally, the canopies help to reduce the drag coefficient of the copter. I measured the effects in a wind tunnel using a two-axes force balance, and the results show that the drag is reduced by something around 30%. See my detailed wind tunnel measurements here.
The handling of the copter is not affected as long as the IMU is aligned parallel to the propellers (you can also rotate the IMU by software via calibration). It seems likely that tilted propellers might become more popular in the future, similar to my 2010 "design invention", the spider frame.

 

What are the differences compared to the Shrediquette GEMiNi?

On the TBS GEMiNi, we don't use my own flight controller (Shrediquette Xmega MPU60X0), but a Taulabs Quanton based controller. In "heading hold" (= angular velocity control), it feels very much like my flight controller. But the Taulabs also has a "stabilize" mode (= angle control), which makes it more suitable for the broader audience and for beginners. Taulabs additionally has a large number of  interesting features that I like a lot.
Furthermore, the TBS version is slightly larger and it has a canopy with a larger volume. This allows for using larger batteries, a broader range of video transmitters and larger receivers (hence people can install the gear they want). TBS selected some very nice and light custom T-motors, these are much better than the cheap turnigy motors I initially used. The ESCs were also developed by TBS epecially for the GEMiNi.

On my balsa/glassfibre sandwich chassis, the motors are mounted with 10 degrees tilt by using some preliminary construction. TBS had the great idea to deform the whole arms in order to get the 10 degrees tilt. After some tests, they however decided not to use a sandwich frame.
There are also no LEDs on the canopy. This is because it is team black sheep that produces the copter and not team christmas tree sheep. But LEDs can easily be added to facilitate LOS flight.
For me, the most important difference is the 4S capability. The ESCs I had to use in the Shrediquette GEMiNi were actually designed for 2S and I was using them at 3S. The custom TBS ESCs allow to use 4S (which I do all the time), that makes the TBS GEMiNi pretty fast.


The most important question: How to convince your wife that you need to get the TBS GEMiNi...

I started working on the GEMiNi while it was clear that I'd soon become father of twins. So I decided to make something beautiful and dedicate it to my gemini girls. The idea was to sell some canopies and invest the money in diapers. Now, I am extremely happy with the result (the girls are just awesome), and each TBS GEMiNi somewhat actively contributes to bringing them up. I am sure that is something your wife would support :-D


GEMiNi girls on my custom longboard
Location: Bremen, Deutschland

Comments

  1. atr0n16 August 2014 at 23:42

    I can't wait! You, site, are a genius.

    ReplyDelete
  2. Anonymous17 August 2014 at 04:04

    I'm not sure my wife will see the benefit of a tbs Gemini hahahhaha

    ReplyDelete
  3. aliyaa19 January 2016 at 14:54

    It is so easy to purchase video testimonials online by consuming less money and time also. This is great services if you believe. ..

    ReplyDelete
  4. Benoit16 August 2018 at 15:47

    Bonjour, je pense que avec une carte de vol omnibus MPU-6000 Il y a une redondance au niveau des moteurs, dans le cas ou 1 moteur s'arrête les 2 moteurs de part et d'autre prennent le relais et stabilisent le rotor hexa?

    ReplyDelete
  5. Unknown16 April 2020 at 03:31

    Super impressed with the TBS Gemini, I have two :-)
    My only disappointment was real flight simulator didn't have it as a flight model..
    I'll have to figure out Blender and add the model so I can fly it during lock down ;-)

    ReplyDelete

Post a Comment

Popular posts from this blog

My 15 inch long-range setup for 2020 (with CAD files)

-
Image
This is my latest 15 inch ultra-long range setup with 50 minutes flight time: Propellers: 15x5.5" Tarot with custom hub  Motors: T-Motor MN3110 470 kV  Frame: 240g custom carbon structure  Lipo: 2x 4S 4000 mAh SLS 20C (parallel)  Camera: Micro Runcam micro sparrow  Firmware: INAV  FC: Holybro Kakute F7  ESC: Tekko32 F3  GPS: BN-180  Compass: QMC5883L  Receiver: FRSky R9 slim+  Hovering flight time is 50 minutes at 8.5 Amps and 40% throttle. Current goes up to 12 A when flying 50-60 km/h. Flight characteristics are really good when tuned properly (you'll nee a HUGE D-term). Here is the CAD file of the frame. INAV 2.4.0 PID settings:  set mc_p_pitch = 85 set mc_i_pitch = 60 set mc_d_pitch = 150 set mc_p_roll = 85 set mc_i_roll = 60 set mc_d_roll = 150 set mc_p_yaw = 200 set mc_i_yaw = 70 set mc_p_level = 40 set mc_i_level = 10 set max_angle_inclination_rll = 500 set max_angle_inclination_pit = 500 set dterm_...
Read more

Finished I²C to PWM converter and TriGUIDE mini

-
Image
The last nights were a bit shorter for me, since the PCBs I ordered at bilex-lp.com arrived. They look really good and seem to be of high quality (I ordered a different "solder resist" colour, well, I like bright colors, but anyway... ). So I had the opportunity to do my very first SMD solderings. This really seems to be comfortable... I will completely switch to SMD I think. The I²C to PWM converters work! Here are the features: Weight under 1 g Works with (most likely many) standard ESCs (currently tested: HK SS 18-20A, ...) I²C address selectable via solder jumpers (4 standard mikrokopter addresses dec 82, 84, 86, 88) Refresh rate selectable via solder jumpers (417 Hz, 292 Hz, 155 Hz, 49 Hz) Pulse width (I²C 0-255): 990µS - 2010µS Pulse width at startup (3 s): 920µS Motor off when no I²C connection longer than 256ms Motor off when microcontroller crashes (veeeery unlikely) Powered by the BEC of the ESC, or by an external 5V source (prepared as well) Very eas...
Read more

Aerodynamics in racing multirotors!

-
Image
Why future racing copters really should look different. by Dr. William Thielicke aka Willa aka Shrediquette ABSTRACT In this article I try to demonstrate why FPV racing multirotors need to look different. Some small modifications to the frame would (in theory…!) result in 70 % higher top speed! All that needs to be done is to align the arms parallel to the propeller flow, and to tilt the main body of the copter by about 40 degrees. I am presenting a very simple and robust racing copter design that incorporates these ideas. Furthermore, I am calculating the aerodynamic drag of different copter concepts using basic equations. The aim of this article is to make you realize the importance of aerodynamics and to stimulate people to design more innovative racing frames. INTRODUCTION Until recently, multirotors were mainly used as a “hovering device” and the top speed of these copters did hardly matter. Now, multirotor racing has become popular and all competitors are seeking ...
Read more

More propeller tests

-
Image
Recently, I discovered some small counter-rotating propellers that I didn't know before. I ordered some and did some tests. The red 4x4.5" props look really good, nice thin airfoils and a good precision. During the tests, they made the least amount of noise, and are currently my preferred ones. The performance of the 4x2.5" props is even better, but they have a pretty terrible sound and seem to be less balanced. Both propellers outperform the AirAce propellers, but this is not really a surprise because the AirAce have a smaller diameter and more blades. What is also interesting is the weight of the propellers. A propeller with a lower weight potentially has a lower moment of inertia which is beneficial for the control loops: AirAce: 2.1 g 4x2.5": 1.5 g 4x4.5" : 1.3 g So this is an advantage for the 4x4.5" propellers, especially because the weight of this propeller is more concentrated to the center, which should further lower the momentof inertia. ...
Read more

Part 1/3: Side Force Generators (SFGs) in FPV Racing

-
Image
Summary: FPV racing multirotors with side force generators (SFGs), will drift less during turns, making them potentially faster on race tracks  (watch the video comparison here ) . But the SFGs need the be carefully placed and dimensioned, so that aerodynamic centre and centre of mass are at the same position. Otherwise it will not work.  Introduction Recently, I was thinking about how to improve the handling of racing copters. I noticed since quite a long time, that different copters behave quite differently in fast turns: Some drift quite a lot (especially when they carry a larger battery or an action cam), others drift less. I was always preferring copters that drift as little as  possible. That is also why I am trying to reduce the weight of my copters as much as feasible. The amount of drift depends on the weight of the copter and the lift and drag of the fuselage for sideways air streams (side-slip). The larger the lift and drag, the more side force the fusel...
Read more