Randy Sonnicksen's Blog (13)

Changing Direction

Well, the day finally has come when I am ready to give up on this endeavor. My goal was to build a manned, internal combustion quad copter.  I will not say the project was a failure because I learned so much on my journey, but I just see other avenues which seem more promising.

Of note, from the project I did successfully build a variable pitch,…

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Added by Randy Sonnicksen on November 13, 2018 at 5:30am — 2 Comments

Bearingless Rotor - Update

Test Video

I was finally able to perform a test of the new drive test stand.  The previous test stand used a 4-stroke engine and a less rigid test frame.  This test stand consists of a 6.5 HP, 2-stroke DuraForce engine coupled to a V-Belt centrifugal clutch with a…

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Added by Randy Sonnicksen on June 12, 2018 at 8:48am — No Comments

Servo Redundancy

I continue to develop my "full scale" gas powered, variable pitch quad-copter.

After watching the video below at 

Amazing DIY Projects

I realized (more vividly) how vulnerable a quad is to any fault in the control system.

Then I saw his video…

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Added by Randy Sonnicksen on March 14, 2018 at 7:12am — 11 Comments

Bearingless Rotor for Variable Pitch Quadrotor

This video shows the fabrication of a prototype bearingless rotor hub/blade design.

The rotor diameter is 93 cm (36.6 in) and will operate at 1,410 rpm generating 2,000 g's of acceleration at the rotor tip, and developing 1,600 Lbs of tension in the flexelem rod due to centrifugal force.  The blade (pair) is designed to generate 104 Lbs of lift with a power consumption…

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Added by Randy Sonnicksen on March 28, 2017 at 8:12am — 3 Comments

Multi-Rotor Scalability

This is an analysis of the variables which affect the ability to control a multi-rotor as the size is scaled up.

This will show why at some point, variable pitch must be introduced.

I hope to follow this with another article which includes Phase Margin and Gain Margin, but right now I'm trying to refresh my memory from 30 years ago on Laplace…

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Added by Randy Sonnicksen on April 22, 2016 at 3:41pm — 23 Comments

Full Scale Quad - I Frame Design

Here is a concept shot of what is a continual evolution of designs.  This is way off in the future, but is the end goal of what I'm working towards.  Now that I'm starting to acquire actual parts and pieces I'm a bit concerned about the weight.  But first things first, and one step at a time.  I still have yet to build even one good rotor blade, but I do have a…

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Added by Randy Sonnicksen on March 31, 2016 at 8:17am — 19 Comments

Full Scale Quad - Composite Rotor Blade

Here are some photos of my progress on the rotors for my full scale quad.  This quad design targets a 200 kg gross wt with 4 rotors of 2.5m diameter.  It's mot much progress, but if you're interested here are the pics.

Rotor Tip Weights

Rotor Tip Weight against leading edge (fiberglass) rod.…

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Added by Randy Sonnicksen on March 4, 2016 at 10:07am — 7 Comments

Bonding Parts: More Area not always the answer-Joint Design CRITICAL

This is a picture of an assembly that is part of my full scale (human size) quad-copter rotor blade.

For background, the FlexElement is the structural member that will connect the rotor blade to the rotor hub or head. (shaft). The leading edge rod is an internal structure to give the leading edge of the rotor blade airfoil durability for small impacts.…

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Added by Randy Sonnicksen on March 3, 2016 at 12:41pm — 9 Comments

Sand Casting Rotor Tip Weights

This is an "exploded" view of my rotor design.  Leading and trailing edge foam cores moved out of position to show internal details.

This design features a cylindrical bearingless rotor root, with droop stop.  Airfoil shaped pieces on inboard and outboard ends of rotor airfoil provide an equidistant path for fiberglass cloth layup, to minimize…

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Added by Randy Sonnicksen on February 9, 2016 at 8:00am — 1 Comment

Composite Bearingless Hub Part 1

Picture above is first prototype of fiberglass bearingless hub design.  The idea of this design is to allow flapping and twisting (pitching) of the rotor, but have limited flex in lead/lag. 

This rotor hub is 24" long and 4" wide in the center.  Was made with Qty 10 - 24" x 2" strips of 6 oz plain weave fiberglass cloth.  Bonded with Fiberglast…

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Added by Randy Sonnicksen on November 26, 2015 at 10:34am — 5 Comments

Bearingless Rotor

My rotor hub design continues to evolve as I learn more about the complex forces and motions of a rotor system.

One of my goals of this project was to keep it simple.  Ideally as simple mechanically as a small electric quad, but as discussed in a previous post, that is not the desired approach, so I'm designing a "collective only" variable pitch rotor head, not unlike…

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Added by Randy Sonnicksen on September 22, 2015 at 12:00pm — 15 Comments

Composite Rotor Blade: Spar Construction

As mentioned before, I'm basing my full scale quad design around a 4m rotor diameter. That makes each rotor blade 2 m long. I've decided on a NACA0012 airfoil which is commonly used for full scale helo's. This is a symmetrical airfoil with a glide ratio of about 60:1. I'm planning to build the rotors of composites with E-glass fiberglass cloth, epoxy resin and…

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Added by Randy Sonnicksen on September 9, 2015 at 1:30pm — 2 Comments

Full Scale Quad

A few months ago, I read the Wright Brothers biography by David McCullough. It inspired me to create. I have always been interested in flight and have enjoyed RC airplanes in the past. The widespread popularity of the quad-copter has sparked a new interest for me.

I am a mechanical engineer, and work in the process control industry. Part of my job…

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Added by Randy Sonnicksen on September 9, 2015 at 1:30pm — 4 Comments

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Season Two of the Trust Time Trial (T3) Contest 
A list of all T3 contests is here. The current round, the Vertical Horizontal one, is here

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