K-1: Introduction and Preliminary Design



          I am creating this blog to document the building of my first full-scale unmanned aerial system. As an aspiring aerospace engineer, I am seeking a practical, hands-on building experience that surpasses kit-model building and multicopter work that I have done in the past. It is my hope that this project will provide insight into every facet of the engineering process, from inception through a maiden flight. As a project, the K-1 is intended to bridge the gap between my experience in RC model/multicopter building and flying, and my fascination with commercial/military unmanned aerial systems. The K-1 will be a low/medium altitude, low airspeed, and high endurance unmanned aerial system as a prototype for surveillance, security, and surveying (in theory).

To be consistent with the convention of naming aircraft after birds of prey, I am naming this UAV the Kite (all the cooler names [falcon, raptor, etc.] were taken).

So far, I've purchased a 33cc gas motor and associated accessories as well as bulk epoxy (West Systems 105), carbon fiber cloth, CF tubes and sheets. 

The wings will be 5.5 ft long each, with a 25% taper on the outer third of each wing and a 2° dihedral angle. They will be 3D printed, covered in carbon fiber/epoxy and supported from the inside by CF tubing. See above.

The K-1's airframe and performance specifications are heavily based on, and inspired by The UAV Factory's Penguin C and UMS Skildar's F-330 UAS, with the following speci


  • Wingspan: 11 ft
  • MTOW:30 lbs.~44 lbs. (pending fuel consumption rate calculations)
  • Cruise Airspeed: ~20 m/s
  • Endurance: (pending fuel consumption rate calculations)
  • Takeoff/Recovery: Runway (working on parachute recovery)
  • Powerplant: 33cc Gas Engine

(I'm still working on these)

Besides the aforementioned corporations, Gisela and Joe Noci's blog has been quite helpful in determining my airfoil choice (S7075 [as an improvement over the Clark-Y]) and wing construction methodology. 

Since it is my first build, the K-1 will be far from optimized, but I've got the whole summer to build the K-2 and K-3. It'll be the proverbial first pancake that is always burnt. 

Alex Frye

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Comment by MarioSpeedwagon on April 24, 2016 at 7:25pm

Thanks for posting, Alex! Looking forward to your progress. Also, glad to see you're following Gisela & Joe's work...their tail boom co-ax prop is a work of art. Good luck! 

Comment by Gisela & Joe Noci on April 25, 2016 at 3:25am

Hi Alex,

Note that the S7075 should be used with a turbulator....Also, I have since moved from the S7075 to Martin Heppeler's MH115 - this has proven very hard to beat for Reynolds numbers around 150K to 300K. It has been a very worthwhile change. Good luck! Pain mixed with lots of pleasure await you..




Comment by Alex Frye on April 25, 2016 at 8:33am


So far, I'm getting a Reynolds number that is just a bit over 150,000 – I'll switch to the MH115. Thanks for the advice!



Comment by Tiziano Fiorenzani on April 29, 2016 at 6:42am

Sounds like fun... Good Luck!


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