Vespa

Vespa - Stretched X racing quadcopter (November 2017)

Trade offs are unavoidable

  Vespa is a second racing quadcopter I built following Wazowski. The name Vespa comes from the scientific name of Hornet, one of the largest type of Wasps. The drone visually is sleek, relatively large for having 5 inch propellers. Hence the name Vespa. Vespa was originally designed to be my primary racing drone, taking Wazowski's place. 

The goal of this project is to build a racing drone focused on:

• aerodynamics (streamlined canopy)
• structural integrity
• high thrust to weight ratio

Parts I used for the build are:

Frame	QAV-XS Stretch-X with PC shell
Motors	Racerstar BR2306 2700KV
Flight Controller/ESC	Racerstar StarF3S 30A
Receiver	Frsky XM+
Beeper	Super Loud 5V active alarm beeper 9*5.5mm
Camera	RunCam Micro Swift 600TVL
Video Transmitter	EWRF-e7082TM
Battery	Infinity 4cell 1500mah 70C
Propeller	DAL T5045 V2
Connector	XT60U
Capacitor	Panasonic 1000uF 25V electrolytic capacitor radial

Mid assembly

  I am using an all-in-one flight controller that includes 4 ESCs, OSD, 5V BEC, etc. It is amazing how drone technology advanced within the last few years. This allows very clean and low profile build and all the components should fit into the canopy's limited space.

Soldering complete

  Vespa is based on stretched-X frame, which is a variation of the traditional X shaped frame. The frame is stretched in length wise so that there is more space between the front propellers and the rear propellers. The idea is that as the quadcopter advances forward, the front propellers create turbulence and the rear propellers end up taking those disturbed air. Giving more distance between the front and back props will reduce this effect thus making cleaner flight characteristics.

Camera mount was designed using solidworks and then 3D printed with PLA plastic

Close view of the internal electronics

   Capacitor is added next to the battery connector. It is common way to reduce electrical noise. More effective way of doing so would be adding capacitors as close as possible to the motor (source of electrical noise) but that would add more weight and since there is limited space inside the canopy, I used only one.

  Also, the video transmitter I am using has smart audio feature. That is, I can adjust the video transmitter's power output and frequency through OSD and radio transmitter without doing so manually. This is a very nice feature to have especially when you are flying with multiple drone racers and have to switch VTX setup frequently.

Build complete, Side view

   Motor wires are covered with electrical tape to protect the wires from external objects such as tree branches.

Front view

Rear view

Georgia Tech Unmanned Flying Club

  Vespa improved on every aspect I found flaws from the previous racing quad I built. The frame is a lot stronger (never broke an arm), canopy is aerodynamic, motor is more powerful. However, those improvements brought problems that weren't present in the previous quad.
  Vespa weighs 305 grams and that is 74 grams heavier than Wazowski. 74 grams may not seem a lot but it affects the flight characteristics significantly. Because of that, Vespa is less agile in flight, which is not a problem when going fast in a straight line, but it is bad when flying in race course that has frequent turns.

  Also, the PC shell canopy wasn't as tough as it should be. The front part of the shell broke off easily from mild crash and long crack lines were starting to form (that's what I get for buying the cheap chinese frame off from ebay for 1/4 of the original price).

Canopy damaged, cracks forming...

  The video transmitter I used for this build had good features (smart audio, light weight), but the video it was transmitting wasn't clean enough for flying comfortablely. Edit: turns out I had the antenna too close to the main power wires. EMI was distorting the video quality and after re-positioning the vtx, the video quality was much cleaner.

  I didn't like the problems above (especially the 74 grams heavier aspect) so Wazowski still remains to be my primary racing drone. Vespa is still a great, reliable quad so I'll be using this primarily for free style flying or as a backup to Wazowski for racing.

  From this build, I learned the importance of minimizing weight and how it can affect the flight characteristics. Every gram counts in the world of quadcopters!

For improvements on future build:

• sub 200 gram racing drone (not including battery)