March 30, 2017: Scrapped
Well it’s kind of sad to say, but I’ve decided to scrap this project. In an attempt to keep the cross section as small as possible, I had to compromise on strength and it did not survive very long. Truthfully, my heart was never into it because the design just didn’t feel right – I really don’t want to put the time in that is needed to do it right.
However, I did come up with a new design that is a good compromise of strength and cross section. Also, it will probably end up being the next “generation” of projects since it won’t be super-specialized for speed only. I calculated that it should easily hit 140mph with a 5s lipo, only time will tell. There’s that word again, time…
The new project (VX1) is basically a merger of the C series frames and the T150. I hope to have a couple flights by early May.
Update March 12, 2017:
Forecast: cold, cold, and colder. I don’t fare well in this weather (currently fighting a cold). This has been agony waiting for spring to return…
Update February 26, 2017:
I finally put aside the time to assemble the rest of the T150. It’s definitely not pretty or perfect – the workmanship has much to be desired.
Everything checks out and I have throttled up the motors (without props) several times to see how they sound. All motors are extremely smooth and I would even say they are the smoothest motors I have heard. The final weight of the frame is a hefty 358g without the battery and 613g with. Although heavy, weight is a non factor when it comes to speed – it does affect acceleration and maneuverability, but these are not the goal for this build.
I hope to get at least 1 test flight in over the coming week with a 4s. The goal is to fly on a 6s some time in the next two weeks. The only concern I have a the moment is the speed reading on the OSD. The little bit of flying I did (2 minutes on the C2 project) with this GPS/Minim OSD combination didn’t give good results. If there are issues, I can always fall back on the Tarot OSD.
January 26, 2017: I probably won’t post anything significant until I have the first successful test flight. The goal is to hit 150mph. If everything goes according to other speed calculations of my other frames, this should be attainable.
The design is finalized, but I have not settled on a motor yet. My main concern is the RPM and amp draw and I am leaning toward a DYS fire 2300kv or a Cobra CM-2206 2400kv.
I will be using a Nano Tech 1550mah 65-130C lipo and 30a Super Racerbee ESC’s that will be mounted inside the main body. This will allow the arms to be only 4.5mm thick (4.85mm with streamlined cover) and 14mm wide (this includes the wires to the motors).
After a lot of number crunching from motor data found at Mini Quad Test Bench, I decided upon the DYS Fire 2300kv. The key factor that I was looking for is a motor that is efficient while still turning out a relatively high number of RPM’s since RPM’s are the largest factor in speed, not thrust. In addition to this, these motors can handle a 6s lipo.
Pre-test motor issues:
I did get a chance to do a static 6s test on these motors (without props), but not before removing the shaft screw and preload washer. 3 of the 4 motors were noisy, not due to bad bearings, but due to improper bearing preload.
I ended up removing the screws and washers and used button head screws and a 0.25mm washer instead. One of the motors didn’t need a preload washer at all. Once fixed up, all the motors were extremely smooth and quiet.
A slight modification I made to the bearings was to do a quick wash of the motor bearings with some electronics cleaner and then used some high speed bearing oil – its a bit thinner than the stock greased bearings.
I opted to go with some heavy duty voltage regulators from Pololu to power the electronics:
- D24V10F5 5V regulator – max input voltage of 36V and 1A max output (I was worried about the current rating, but it is plenty)
- D24V22F12 12V regulator – max input voltage of 36V and 2.2A max output
For the VTx. I decided to go with the AKK X1 found on Amazon. AKK is a new name (at least to me) and I have been impressed with their quality so far. Features of the AKK X1:
- 40 Channels
- 25mW, 200mW, and 600mW modes
- Small size: 20.5mm x 28.5mm (38mm including antenna mount) x 9mm
The ESC’s are the 30A Super Racer Bees from Ready To Fly Quads. They are a work of art as far as quality goes and can handle a 6s battery.
Since I am going for the least amount of drag possible, I went with an Eachine Okkan EK1119 which I found on Amazon. The lens on this camera is smaller than most (diameter of 10mm vs 14mm).