HORUS HARPY

DESIGN BRIEF

History & naming

At the end of the 2015 racing season we saw the resurgence of the X-frame. I say resurgence because for many, the X-frame geometry was where this all started. Due to a confluence of uneducated tuners using X-frame configs in their flight controllers on H-geometry airframes and the innovative work by Warpquad, the X became the new black. This frustrated me to no end. Instead of exploring the new, we were backtracking to safe territory and this was called innovative. At the last race of the 2015 IDRA California Cup I decided I would design something that would not only show VTails could be built the same way, but be competitive. This was the genesis of the Harpy. 

Named after the ancient Greek mythological beasts, with beautiful feminine faces and the body of a predatory bird. The Harpies were known to be vicious, cruel and the personification of the destructive nature of the Wind. It is from this legend, that the Horus Harpy draws its inspiration. 

Design

To show the true force of the VTail, the decision was made from early on that the hardware and software must be in sync. Therefore, the geometry was matched 1:1 with the Cleanflight VTail mixer. This immediately changed the responsiveness versus the Kestrel. Yaw was even faster and the the frame, even more acrobatic.

From there, the goal was strength and a lightweight chassis the likes of which had never been seen before in a VTail. All three arms, the front two and the tail, all butt against one-another, similarly to what you have seen with X-frames, but employs a unique 'V' shape which allows each component to arm to displace stress to the other two. This has never been done in a VTail and provides incredible levels of rigidity. The shortened tail over the Kestrel eliminates any tail-torsion and camera mount provides a strong crash-resistant front end while allowing for camera angles up to 90 degrees! 

The arms employ 4mm carbon and are individually bolted to allow you to swap to different arm lengths (future development) and make repairs easy. These are bolted to a 2mm plate giving you and effective 6mm structure at the core. At each step efforts were taken to reduce hardware and add lightness, the result being the lightest 250mm VTail to date with the ability to run up to 6in props! Finally, there is a VTail racer capable of holding it's own in Dubai in 2017. All said, the Harpy is probably our favorite frame design yet. 


FEATURES x included parts

  • Designed in the USA
  • Unique Arm/Tail interlocking design
  • 2 Available CG Orientations
  • Up to 90 Degrees of Camera Tilt
  • 2.1mm Lens Compatible
  • 4MM 3K Carbon Fiber Arms
  • 2MM & 1.5MM 3K Carbon Fiber Plates
  • 2 Engineering Grade 3D Printed VBlocks
  • Titanium Screws / Aluminum Locknuts
  • 40mm and 30mm Aluminum Standoffs 
  • Free part files so you can print replacement parts
  • PIDs available online
  • Front & Rear Motor Bumpers
  • Future Accessory releases to customize your own

HARPY GALLERY

HOW ARE VTAILS DIFFERENT TO FLY?

VTails can best be described as a hybrid of an airplane and a quad. It still has all of the flight mechanics of a quad but it definitely likes to be flown on the nose with the tail in the air. It likes the CG to be a bit forward and your turns to be coordinated (because of this, when you throttle up it likes to push forward so you may have to pull back on the elevator). Roll tends to self level a bit due to the degree of the rear feathers, allowing the pitch axis to really lock in. Yaw, as you can imagine is huge. Its a very interactive frame, needing you to be always on the sticks, tweaking and adjusting it. Overall it is challenging but in a good way. It actually pushes you to be very committed and to always fly fast,... in fact it demands that of you.

STYLE & AERO

Continuing with the tradition of the Kestrel, the Harpy was styled to be as aggressive as possible without sacrificing strength or rigidity. The introduction of the Eye of Horus detail was something I've wanted to do for quite some time and gives quite a character to the overall design. Every opening is designed to break-up airflow that would otherwise be caught and add drag. The 'body' within the top and bottom plates was designed to be as narrow as possible while providing enough rigidity for the VTail and helping the Harpy slice through the air. 

TWO CENTERS OF GRAVITY, ONE FRAME

With each Horus Harpy, there are two sets of standoffs. One set of 40mm standoffs and one set of 30mm standoffs. While this is atypical, there is logic behind it. With the 40mm standoffs, the top-mounted battery allows the CG to sit above the thrust line, making roll transitions faster and the airframe twitchier as a whole. With the 30mm standoffs, the CG point drops below the thrust line, slowing down the roll moment and making a tamer craft. While the trend has been towards lower-profile builds, this is purely aesthetic, as dropping the CG too low will numb the responses of the airframe. In this case, the higher CG is the more exciting bird to fly. 

 

ENGINEERING GRADE 3D PRINTED PARTS & Accessories

Horus employs a unique blend of P.E.T. designed for engineering functional designs, rendering our parts stronger, more durable and functional than temperature sensitive PLA and flexible ABS. 

However, if you own a 3D printer, you can download replacement part files to create your own crash kits. We provide this to you for free because we don't believe in gouging our customers.

We are continually developing new parts and accessories to improve the dynamics, add features and personalize the style of your Harpy. 

 

RECYCLABLE 3D PARTS

Since crashing is the norm in FPV racing, we create a lot of waste from broken parts. Every single 3D printed part on the Harpy is therefore recyclable, capable of being ground and reused at a later time. Not only is our material strong, but it helps us reduce the impact of our sport on the environment.

 
Horus Harpy
150.00
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