[OpenRelief Developer] Awesome news: someone just donated an open source airframe design

Shane Coughlan shane at openrelief.org
Fri Jul 6 10:51:42 BST 2012

That someone is Edward Strickland, a gentleman with a degree in aeronautical engineering, experience with Open Source Auto Pilots and 7 years experience with QinetiQ and UK MoD. He is now working on a commercial Vertical Take Off and Landing (VTOL) airframe, and kindly decided to release his existing Conventional Take Off and Landing (CTOL) airframe via OpenRelief.

This is obviously a significant step forward for us, providing a pretty impressive platform to test flight systems with, and delivering what I believe is the first genuine Open Source Airframe for our community. Eddie has licensed it under the TAPR Open Hardware License 1.0 (http://www.tapr.org/OHL)

You can download the CAD schematics and the bill of materials here:

As soon as possible everything will be uploaded to a website location to fit into our normal hardware release structure. This will mean people can view most of the details online and/or download the detailed files as required. As we move forward with this design, we will use GIT or a similar system to record changes. In the meantime, please record any changes in the README file.

Here is an overview of the specs:
 * Length 1.4 meters
 * Wing span 1.8 meters
 * Chord 30cm
 * Uses counter-rotating motors (redundancy, speed, balance, no torque)
 * Uses remote servos (wing flaperons, the tail surface) for more storage and ease of repair
 * Empty weight 3kg
 * Thrust is 12kgs
 * Max load 12kg (lift at 100mph/160kph is approx 12kg)
 * Endurance is between 1 to 4 hours with existing specifications
 * Wings can be repositioned to change CoG for large payloads
 * Stringers located on the fuselage to carry the wing, landing gear and other items (modules)
 * These channels also hold internal items like the motor via bulkhead rings, for quick changes
 * Fuselage can carry liquids (same diameter as 2L bottle of cola)
 * Can be launched by rail and use parachute recovery
 * Can be fitted with front wheels for conventional landing in rough fields

 * CAD files are from Solidworks

Eddie mentioned that he may be able to obtain some student time to assist with further development after September, and he also provided a few notes about the airframe and development recommendations. 

The first point is that the problem of small scale aerodynamics which produce large drag components at low speed will continually limit range. It's just a fact of this scale of device. The second is that we should not getting bogged down in airframe details, but rather focusing on sorting out essentially modules for our purpose, and then scale/refine the airframe to fit them perfectly. Finally, we should also be careful about lifetime on airframes, with his testing showing that as few as 2 to 3 flights can take a real toil at this scale.

Please note that the propellors are located at the front of the plane, which allows for a simple build and flight quickly, but does introduce the potential issue of damage on landing. There are various ways around this, including parachute, landing gear, flying into a net, even rods which stop the propellor at 3pm position. We will probably plumb for landing gear to start with and see what happens.

Spread the word, ladies and gentlemen. We just took a giant leap forward.



PS: Naturally this does not replace our DragonFly airframe project. We always expected to build a collection of airframe designs. However, Eddie's donation puts us way ahead of where we expected to be. Big kudos.

Shane Coughlan
e: shane at openrelief.org           
p: +81 (0) 80 4035 8083              
w: www.openrelief.org

Professional profile: http://www.linkedin.com/in/shanecoughlan

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