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

Comments

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

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

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

    ReplyDelete

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