How to Build a Gremlin | Flite Test

by FliteTest | May 1, 2017 | (6) Posted in How To


We are so thankful for your support and excitement about our newest design: the FT Gremlin! Without your passion for the RC hobby, we wouldn't be able to make these designs possible! Last week, we listed it online and your response was incredible! In this build video, TJ takes you step-by-step to create your own FT Gremlin!



Beau_LunaWolf on May 2, 2017
Would love to see more closeup pictures of all the designs so folks can see how theirs will go together.
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Huffheinz on May 2, 2017
Great video! Nicely done, TJ (and FT team). I ordered my gremlin with the TJ frame last week as my first quad build. I have to admit that I was a little nervous about the tiny size and programming the FC but, after watching this video, I am confident that I can play along with the home game and get this sucker to fly.
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First JT great Quad design and how to video! When sauldering i used both top and botom posts every other since it was so small, made for an easer build proses for my fat fingers.
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Kevinjt4 on May 3, 2017
Would the Lemon Rx DSM2 Compatible Satellite Receiver (found here: work in place of the Spektrum Rx TJ is using in the video?
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Michael763 on May 22, 2017
I am getting ready to find out. I was wondering also.
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Michael763 on May 23, 2017
This page shows the settings are same as the Spektrum Rx TJ uses in the video.
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dr_nick on May 3, 2017
are these gonna available in europe??? I WANT ONE "for my son" ;)
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davereap on May 4, 2017
search for emax f3 femto , that's the controller board used, its sold on its own and in the emax pack with esc's motors, props.. but no frame and no RX, that for you to add
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davereap on May 29, 2017
and if you want a small frame look at the tarot 120 , its a good match to the size we need for the gremlin build
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davereap on May 29, 2017
flitetest plans now out for download on Sponz's plans list
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webbhm on May 5, 2017
Betaflight is a Chrome application. Load it from the Chrome web store. This is not a download from Github (though that is where they store the hex files).
This was not clear, and it took me a while to find the app. Betaflight was already flashed on my F3 Femto when I received it with the Gremlin.
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Bromego on May 6, 2017
I modeled my own frame after the QAV210, and call is the QAV-M (Mirco) 110. Check it out on thingiverse.

I made the model work with both the EMAX power pack micro system motors or the a standard 9mm 1104 motor mount
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JimCR120 on May 8, 2017
EMax Connection Problem
1st, let me say thank you for your desire to make this hobby as accessible as possible.
2nd, I'm confident this will get worked out though a bit frustrated I haven't figured out the problem.
3rd, the problem is I can't get the board to be recognized on my Mac. My tricopter is recognized no problem in both CF and BF but the F3 Femto neither. Tried various cables and ports, no joy. Any guidance would be appreciated.
Lastly, you guys rock. I thoroughly enjoy how you all support the idea of family. God bless you all.
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JimCR120 on May 9, 2017
Update, Today I got connected! It was the USB cable. I had tried 4 others (2 each of 2 types that I believe came with some blue tooth peripheral devices) and decided I needed to try an entirely different cable. I found one in the basement that once plugged in, everything acted differently. Phew!

Suggestion: Mark your USB cables to distinguish the ones that accompany devices for charging purposes or at least mark one as a good one for actual data use.
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russj48 on May 12, 2017
Hi all, I also had problems getting the flight controller connected. My problem was also the cable and I tried about five or six before finally getting it to work. You must have a data cable, not just a charge cable.

Even after getting it to connect to beep when plugging it into the computer, I still had problems getting the drivers set up. I finally found this youtube video that explains everything very clearly. After following along and getting the drivers set up everything worked. Hope this link will help others having problems.

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marc71 on May 19, 2017
Where do i find the downloadable versions plans?Im very new in this hobby.
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davereap on June 7, 2017
On sponz's plans thread towards the bottom
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bthurgood on May 23, 2017
Interesting to note that TJ set the ESC protocol to OneShot125 in Betaflight not the supported DShot series of protocols that these new ESC's support. It is unfortunate that the Emax Femto F3 FC does not natively support DShot (motor four will not work) protocol and you have to resort to a remapping exercise.
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Scott594 on November 20, 2017
Same problem here. Thank! Almost changed out ESC 4.

Note to FT Guys, a heads up on this in the FC envelope would be a nice touch!
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davereap on June 7, 2017
Thank you... by following the video I managed to build my version of the gremlin, using a cheap vortex 120 size frame, so many thanks for the detailed build video.. the quad is working..
I did run into problems at the end when I could not get the blheli suite to recognise the quad at all , no connection at all.. however there is a newer blheli configurator app that runs through chrome.. This app worked perfectly , connecting straight away, and using the app, I was able to flash the latest bl firmware and set the correct motor directions very easily, the chrome app is much easier than the blheli suite method..
The blheli configurator app and the betaflight can be run at the same time, and by disconnecting from one you can then connect to the other, swapping back and forward is easy.. which saves time..
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Ran D. St. Clair on July 13, 2017
I recently completed the build of the Gremlin Power Pack G with the TJ Williams frame. Actually, I let Flite Test do the physical build, but I still needed to set it up with my DX9 transmitter etc. , so I picked up the build video at about 58:26. From that point onward, the build video is quite poor, mostly due to being incomplete.

I did not need to flash the firmware myself, but at 5:54 TJ claims the programming was successful, but the video clearly says, “No response from the bootloader, programming FAILED”. This is the sort of thing that will drive a new user insane….

Here is a list of some of the critical information that I consider to be missing:

1. What kind of USB cable do you need?
2. Where do you get Betaflight, including the user documentation?
3. How do you install it on your computer?
4. Where do you get the special driver that it needs and how do you install it?
5. Where do you get the BLHeli Suite, including the user documentation?
6. How do you install it on your computer?

At the very least, links need to be provided to the locations where this information can be found. Poking around on the internet among all the mis-information and malware is not a good option.

The Transmitter setup is poorly described. There is no mention of using trims or sub trims to center the controls and prevent gyro drift. There is no mention of the endpoint or travel settings required. This is especially important for throttle as the stock 100% throttle travel is insufficient to allow the flight controller to arm. It requires 120% minimum.

There is no mention of AutoLevel calibration in Betaflight. Mine was way off. Between this and the improper trim settings the Gremlin would be unflyable for a beginner.

You really need to slow down when working on the computer. Even with pause and rewind it is difficult to see what you are doing.

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Ran D. St. Clair on July 15, 2017
The Gremlin page in your web store lists the battery option as "BABYHAWK PARTS - 2S 300MAH 35C BATTERY", and the "Includes:" section states "4x Bullet 6A BLHeli_S ESC (1s-2S Support)", but the "To Fly You Will Need:" section calls for "Battery: Hyperion 450mAh 3s 50c". So will the Gremlin support the use of 3S batteries or not? Please fix your web store listing.
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Gebomb on August 17, 2017
Does anyone know what size heat shrink tubing I need to cover the ESCs? Thanks!
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FireFlyer on December 17, 2017
Can you tell me where to find dimensions for the motor mounting holes? also a general idea of the overall dimension of the Gremlin, I would like to design and build my own frame this would be great starting info thanks
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How to Build a Gremlin | Flite Test