We are making plans for an online extension to our training program, using the RealFlight software.

RealFlight is a longtime recommendation for beginners to develop their skills. But it also enables you to join online sessions along with others at our virtual Marymoor field.

To join in, start RealFlight, choose Multiplayer from the menu, click Join, and if we have a server currently running you can select the Mar_C-field.  You will be almost instantly transported to our beautiful location, currently hosted in Chris Randall’s basement, to fly whatever plane you select.

Wouldn’t it be great to be able to meet an instructor there, and take a class in advanced or 3D skills along with a few fellow students? You could watch demonstrations by your instructor, see others fly under instruction, then take your turn to have the instructor give you running commentary and advice on your performance.

That’s what we’re thinking. Sessions could be recorded for later review, and for others not yet ready to take part to see what’s involved and to benefit from reviewing classes from some of our most accomplished pilots.

Of course, there’s no substitute for real-life stick time. But where else could you get to fly boutique planes, with a pilot who has decades of experience at your side, without fear of the whole affair going sideways in an explosion of carbon fiber and monokote? There’s no judgement and no shame at the virtual field.

But in case you fear there is, the only chance of embarrassment occurs in the brief moment between crashing and hitting the reset button.

Check out the field whenever you can. It may not always be available, but we do our best. Also, it isn’t available on other flight simulator platforms. For the best experience, you should try a headset with a mic (an inexpensive USB gaming version works well).

We’ll have more info on the virtual training program as plans firm up, and though we clearly can’t provide tech support, we will curate setup and configuration instructions to help get people up and running quickly.

Go on – sign in and crash something *expensive*!

Rob McConaghy is an engineer’s engineer. He solves mechanical and electrical engineering problems, designs and scratch-builds solutions, and is always ready to recognize the experience and contributions of his colleagues. And Rob’s longstanding project – some may say obsession – with Stirling Cycle engines is testament to his dogged pursuit of optimal solutions.

Low noise, zero emission

He’s also remarkably patient with those who are fascinated by this work, yet totally unfamiliar with the technology. An engine that appears to need no fuel. Just hot air. When you see it run, you can’t help thinking it’s kind of magical. “Well, it kind of is!”, Rob says with a smile.

He explains that Stirling engines alternately heat and cool air to create expansion and contraction that drives one or more pistons. It’s a closed system with no intake or exhaust and runs very quietly – it’s sometimes referred to as a silent engine.  The air inside the engine may or may not be under pressure. The principle was invented by Rob’s namesake Robert Stirling in 1816, and subsequently developed by the Philips company as part of the war effort. These are the first engines that could genuinely be called ‘zero emission’.

A mower, a young man, and the start of a mission

The May 1964 edition of Popular Science featured a Stirling-powered lawn mower, and sparked highschooler Rob’s interest. He would go on to design and build the first of many of his own Stirling engines as he pursued a degree in Mechanical Engineering – the early stages of what was to become a career-long preoccupation. Fast-forward to June 24^th, 1987 when Rob, his family and friends visit 60 Acres Park in Kirkland for the maiden flight of his scratch-built plane, powered by a scratch-built Stirling engine of his own design.

1987: world’s first Stirling-powered airplane

It was a unique experiment: the first airplane ever to be powered by hot air. Not so unusual – certainly for RC plane enthusiasts – was the result. The first few flights ended in crashes, “Not because of engineering problems,” Rob’s quick to point out. “Entirely down to pilot error.” But after a few more flights, the required piloting skills developed and the model rose to 50 or 60 feet, to fly for 15 minutes. “There’s something special,” says Rob, “About seeing the engine actually fly an airplane. To me, it was deeply satisfying.”

The engine produced some 20 watts of power, which Rob says is about the minimum required to support a plane. The air inside the cylinders can be at current atmospheric pressure, but in this case, it was initially pressurized using a bicycle pump; increased pressure in these engines provides for increased power at the expense of slightly less smooth operation.  Propane brought the heat, and air passing across exposed coils circling the body of the engine acted as the coolant.

Research, development, and publication

Since that time, Rob has continued to experiment with different designs, materials, and alternative gases to plain hot air. Prestigious publications such as the IEEE Energy Conversion Engineering Conference, and Model Engineer magazine have published the results of Rob’s work as he has continued to evaluate, build, and refine. In one such article Rob says, “I can’t tell you how much time I have spent pondering the ideal engine layout for use in a model.” At that time, he also predicted the eventual ubiquity of electric motors. Like his Stirling engines, they represented a  “..quiet, clean, easy to start power plant.” And Rob correctly predicted that people would eventually be prepared to pay the price in added weight for that convenience.

In common with the fundamental principle of his engines, Rob says the development and progress of related energy conversion technologies seems also to be cyclic in nature. The pursuit of diverse designs for energy conversion has led to the proliferation of options we have today, but some technologies – such as steam, solar, and even hot air – persist, returning in evolved forms to drive new solutions. Steam engines return as nuclear-powered steam turbines, and the oldest source of energy, the sun, can now be harnessed to power a huge variety of devices including trains, planes, automobiles – and even space stations.

From the Northwest to NASA

And, just to prove there is nothing new under that sun, NASA announced in March 2020 a Stirling Cycle engine at its Glenn Research Center that has been running continuously and without any maintenance now for over 14 years.

Today, Rob maintains his interest in Stirling Cycle technology, though recognizes how broadly his electric motor predictions in the ‘80s have, in fact, materialized.

 “My son has a Tesla,” he says. “Though I haven’t driven it.” After speaking with him for a while about his work you realize that, among all the impressive features of his son’s Tesla, perhaps the least interesting for Rob would be the driving part.

Flight video

George Washington noted that, “Perseverance and spirit have done wonders in all ages.” Click here for home video of Rob’s perseverance at 60 Acres.

Click here if you’re impatient enough to jump straight to his record-making successful flight.

Select references

McConaghy (January and February 1996), “A Hot Aero Engine”, parts 1 and 2, Model Engineer magazine

McConaghy (1986), “Design of a Stirling Engine for Model Aircraft Propulsion”. IECEC: 490–493

Image credits: Wikimedia Commons; Popular Science archive; Rob McConaghy. Photography, video transfer: Chris Randall. Text: Richard Machin

Corey Kelmel left the room in awe of his giant scale Taylor Craft scratch build at the March 20th club meeting. Apart from the technical, mathematical, and materials skills involved it was a tour de force in project management as he described the logistics involved in curating the experience of fellow builders, international parts sourcing, and working with specialist suppliers.

He makes his own laser-cut parts. He modifies plans to suit features of full-size planes he’s tracked down. His garage resembles a 70’s discoteque as he shoots lasers to ensure 3-d alignment. And virtuoso Excel skills help manage all that complexity and track progress.

Corey also designs and creates presentations professionally, so that too helped create a particularly entertaining and informative evening.

Check out his presentation here.

This post is designed to capture how our trainer eqpt works, as we sometimes get confusion when we have a problem in the field. So it’s not so much entertaining this time as it is purely instructional. Enjoy (as much as is possible).

Wired Tx/Rx setup

Our wired trainers (DX7/DX7S Txs) are already set up as follows:

• The Master Tx is bound to a plane as normal.
• On the MASTER Tx, turn on while holding down the roller button. (Other radios may have a seperate Trainer menu under System Settings). Select Trainer, then select Pilot Link Master
• On the STUDENT Tx, enter the Trainer menu as above then select Slave. Turn off the student Tx

Notes:

• Warning: never turn on STUDENT Tx once Master/Student is set up per above! (If you do, turn it off again before following ‘To turn on’ below).
• Info: trainer configurations can also be used with the simulator

To turn on:

1. Plug wire into STUDENT Tx
2. Plug wire into INSTRUCTOR Tx
3. Turn on INSTRUCTOR Tx

To turn off:

• Turn off INSTRUCTOR Tx AND unplug both TXs

WirelessTx/Rx setup

Notes:

• Warning: our DX7 Txs cannot operate as wireless Master
• Info: any Spektrum TX can be used as wireless Student

The Master radio must be a Generation 2 or later Spektrum transmitter. This includes: DX6e, DX6G2, DX6G3, DX7G2, DX8E, DX8G2, DX9, DX18, iXn, NXn. (Also the DXe retail version but not the DXeA that comes with RTF models).

1. The Master Tx is bound to the plane as normal.
2. In the Master Tx, go to Trainer under the System Setup menu. Choose Wireless Trainer, then select Pilot Link Master. (This will give you the basic Wireless Trainer setup, with only the first four channels (Throttle, Aileron, Elevator, Rudder) controllable by the student). Select Bind.
3. Turn on the Student radio in bind mode. This generally involves holding the bind button or switch while turning it on, or select Bind from the setup menu. Continue to hold the bind switch on the Student radio until the Master radio indicates “Bind complete”.

Watching extreme aerobatics at the field performed by accomplished MaR/C 3D flyers is always a pleasure. But it can also be intimidating, even discouraging. The maneuvers seem so crazy they are out of reach to the majority of us. You might think there must be computers involved. That new AI stuff perhaps. Or maybe black magic. But pilot Ken Threedee says no, it just comes down to practice. Practice, practice, and a little extra practice.

Also, he says, you need to keep your focus on some fundamentals, especially when you try your first, oh, inverted flat spin. These are an airplane’s four fundamental controls: elevator, rudder, ailerons, and throttle. When you see these guys at the field throwing their planes around the sky, twisting and spiraling tail over prop inches from the ground, everything stems from those four inputs; they’re all they have. Ken says you must remember that each control only and always performs its one crucial function. The rudder turns the plane laterally around its vertical axis. It doesn’t change its direction. Ailerons do the same, around the plane’s front-back axis. They don’t change its direction. The elevator, around the wing tip to tip axis. It doesn’t…well, you get the idea. Finally, the throttle makes the plane go forward.

You already knew all that, right? But when you see those complex 3D patterns you forget what you know, throw up your hands and return to the whole black magic thing. But Ken’s point is, remember that even the most complex sequence of patterns, the most violent change in speed or direction, can only be performed by setting up combinations of those four, simple, single-purpose controls. He refers to those controls being used to “add energy”. For example, energy imparted by a little more throttle and a touch of opposite aileron that converts that inverted flat spin from a graceful if unremarkable descent, into wild tail-out commotion.

So next time you’re at the field taking a break and watching Ken defy gravity and whatever it is that holds his planes together, think about how even when things seem most mind-bogglingly complex he’s only using those simple controls to rotate the plane around each axis x, y, and z – combined with more or less throttle. That’s how you can begin to understand what you’re seeing, and build your own collection of 3D skills.

And that’s all there is to it.