July 24, 2017:
EARLY WRAP UP: Yes, after just one speed run (161.1 mph and 100m opposite direction average of 157.7 mph on 5s), big breakthroughs in frame design has caused me to put all efforts toward project VXR-190 which should be good to go next week (I still might make a flight or 2 more with the VXV).
- VXV: The “Velocity” Derivative of the VX1
- Documentation of Data
- All About the Props
- Frame Bill of Materials
VXV: The “Velocity” Derivative of the VX1
The frame will end up being nearly twice as heavy as the VX1, but it will be well worth it. The goal is to have a very durable and efficient all around flyer that can attain speeds of 180-190mph with a 5s lipo. I always feel way off on the speeds on these projects, but calculations have been very accurate so far and actually put this build at 190+ mph! However, I like to keep predictions conservative.
After all the research, I was able to see how the VX1 was capable of reaching speeds near theoretical prop pitch speed:
- Low drag coefficient = less torque required to fight drag
- Low drag coefficient = more torque for RPMs
- Careful balance between motor kv, prop diameter, and voltage kept prop tips from entering transonic speeds (very important!)
Keeping with the same ideas, drag will be further reduced on the VXV and prop pitch will be increased to 6.
Differences from the VX1:
DYS fire motorsCobra Champion 2207 2450kv motors
- Spedix HV 30a ESCs
6s capable5s lipo (click here for more info on this choice) 8mm motor arms10mm arms reinforced at weak points with 8mm and 12mm carbon fiber tubes
- Use of solid copper wiring for clearance issues (between ESCs)
- More streamlined body
- Thicker walled carbon fiber body tube
- Longer body to increase strength around arm holes
- Longer arms to accommodate APC 5.2 x 6.0 props
Documentation of Data
This time around, I will be addressing another goal I wish I had done with the VX1: video of the frame being fitted with the 5s lipo, flown, and landing (or crashing). Osd video should be much better this time too. Again I will use GPS for recording speeds and distances flown. Much more info will be presented and dissected.
Once again I went with Cobra 2207 2450kv motors from Prop Shop
So far, only on flight day with speed runs. Tuning is still subpar, but I gave it a go anyway. Not posting any super-in-depth analysis yet since I am not done pushing this frame.
- 4s lipo: 131.5 mph opposite direction over 100m, 135.9 mph max
- 5s lipo: 157.7 mph opposite direction over 100m, 161.1 mph max
- 6s lipo: Cancelled to begin work on the VXR
One thought on “VXV”
Finally someone THINK before he made some quadcopter. Flight is not only a matter of calculations but of UNDERSTANDING the phenomena. Congrats. The “z” shape is the right path I assume, but the arms should make a 45 degrees angle with the body, not 90 (only an opinion but you can easy see why). I will follow your progress. Thanks for sharing.
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