Physics, Freshmen, Furniture… and a Grant Win!

There hasn’t been a lot of action on this blog site so far this school year—but not because there aren’t things worth writing home about! As you can imagine, I (Mr. Meadth) have been much busier on the ground each day with cleaning and supervision, let alone teaching the engineering class.

But some things are worth documenting and celebrating. So let’s jump in!

1. Four New Freshmen

We took four new engineering students into the freshman class. A big welcome to Hunter, Abby, Teleios, and Eliana. These junior engineers are hitting the ground running, despite all the challenges. They are learning trigonometry before their time, taking baby steps into the world of computer-aided design (CAD), and just generally being awesome. Welcome, freshmen!

Hunter, Teleios, and Abby (Eliana couldn’t make this
photo, but she’s just as much a part of this group!)

2. College-Level Statics… From a Textbook

Despite my propensity to always design my own curriculum from the ground up, I tried something new this year: a textbook! It turns out this was the perfect year in which to do this, as it matched well to the statics studies that we’ve always done anyway. Don’t be led astray by the name—Statics for Dummies—the lighthearted tone helps high schoolers get through those pesky equations. For those engineering parents out there, you’ll find all of the fun you can handle in vector calculations, force couples, and free-body diagrams.

3. Independent Mode

This is a grand experiment, and one that we committed to from the start of the year. Can we commit to a full year of engineering studies in independent mode? Some would say that it’s never been tried, but this is the year to come up with new solutions! Despite the absence of stimulating classroom discussions, this has allowed students to take seven classes plus engineering, and it allows students to watch at their own pace. Students have watched 18 videos so far this year, and responded with written assignments and discussion boards. They are now eagerly discussing their community design project in a shared Google Doc, which brings us to Number 4…

Acceleration sums in three dimension, anyone?

If you can’t find the centroid of a composite area,
you just can’t call yourself an engineer

4. Community Design Project

I’m so happy with how this project is rolling forward! We have two “clients”, Mrs. Christa Jones on the San Roque campus and Mr. Gil Addison at PathPoint, who works with residents in wheelchairs. Our student teams are busily designing an adjustable standing desk for Mrs. Jones and an adjustable computer desk for Mr. Addison. Both of these designs are required to involve electrical/mechanical aspects, such as motorized lifts or built-in LED lighting. Once the student teams finalize their designs, complete with drawings and CAD models, I (Mr. Meadth) will be building their designs myself—in the interest of staying as contact-less as possible.

5. Lots of Publicity

We’ve received a surprising amount of national-level publicity lately. Our students use the CAD platform Onshape, and Onshape reached out to us to record a video and write a blog article. The video has been up for a over a month now, and the blog article will be published soon. Our Academy was also mentioned in another national publication by the American Institute of Aviation and Aeronautics (AIAA), Aerospace America, because we won a $500 grant to help build our remote-controlled aircraft.

6. Major Grant Win

Is it just me that believes in our outstanding Providence engineering program? Is it just the university lecturers who receive our already-highly-trained students? Am I just blowing my own horn over here? Apparently not! The Toshiba America Foundation decided that our second-semester robotics project was something worth funding, and we are pleased to announce that over $4,000 of the very latest in classroom robotics equipment will soon be arriving on campus. This will be put to use in our Mars Rover project, where different student teams will design, build, and code different components of one big vehicle. I’m looking forward to this one. Thanks, Toshiba!

One of the advanced Vex V5 sets: coming soon!

As always, stay posted for more exciting announcements. Our junior engineers are doing something very different, but making the most of it. I’m confident that their skills and experience will remain at the very highest level amongst similar programs in our area. Keep it up, students!

–Mr. Meadth

Designed, Built, Flown!

You can’t choose the hand you’re dealt, but you can play it to win every time.

Along with every one else around the globe, the Providence Engineering Academy was dealt a tough hand in March. Having worked so hard in the lead-up to the major capstone project—to design, build, and fly a powered tethered aircraft—being asked to complete the project from home was not the situation that anyone wanted. But in the spirit of problem-solving, our junior and senior engineers faced up to the challenge. After all, what is engineering all about if not solving problems?

Our last post on this project ended with the four teams designing various aircraft components using professional-grade CAD software. They had sent their designs to Mr. Meadth, who began to 3D print their fuselages and tails, cut their carbon fiber, and CNC mill their wooden wing ribs, all from the comfort (?) of his garage.

The garage workshop: where the magic happens!

Over the course of several weeks, each team’s delivery bag in the garage began to pile higher and higher with these manufactured components, along with advanced electric motors, lightweight lithium batteries, tissue paper, and other bits and pieces. Every last one of these components had been accounted for in duplicate: in a virtual CAD model and a complex spreadsheet. The CAD model held the actual design for manufacture, visualization, assembly guarantee, and mass/center-of-gravity prediction. The spreadsheet calculated wing and tail lift, which in turn yielded a force and moment balance, and also a redundant center-of-gravity prediction. (Redundancy is not a negative word in aircraft engineering!)

Quick science lesson: the center of gravity (c.g.) is where the sum of all weight is located. In other words, it’s the point at which you could balance the aircraft on your finger, or where you could hang it from a string. It is determined by the masses and locations of the individual components, and it was critical that our uncontrolled aircraft had the center of gravity forward of the wing’s lift force. Without going into the deeper explanation, having the center of gravity as close to the nose as possible means that the aircraft will be self-correcting and stable as it flies. Try attaching a paperclip to the nose of your next paper aircraft and note the dramatic improvement! This is why we ran two separate c.g. calculations using two different method—we wanted to absolutely confirm before manufacture.

Fresh off the printer, ready for delivery!
Sam and Josh work on RUBYGEM, papering and
doping the wings

Mr. Meadth delivered each team’s bag directly to their respective homes. Upon arrival, each team worked hard to assemble the aircraft. This involved inserting carbon fiber spars into 3D printed wing boxes, stringing the wooden ribs evenly along the spars, covering the ribs with tissue paper, and then applying dope (a kind of water-based glue) to the paper. The doped paper dries and hardens into a kind of thin shell. The various electronics components were also connected and secured, along with the tail and undercarriage (landing gear).

At the same time, the simple tethering system had to be designed and implemented. The wooden stand sits in the middle of the flight path, and a 3D printed bearing served as an anchor point for the tether line. The tether was then attached to the wingtip. Some of the aircraft needed a little more rigging to ensure that the centripetal force didn’t rip the wingtip loose!

Fast forward to the big day. Mr. Meadth made a final decision to hold the test flights in the gym, instead of outside. The smooth floor would take one more variable out of the equation, and the enclosed space would keep out any stray gusts. When your plane only weighs about 2 pounds and floats on the breeze, a gentle wind can be your worst enemy!
Thanos steps on to the court!
First up to the plate was Nolan and Pedro. Their purple and grey monoplane had a planned weight of 800 grams (less than a liter of water). The wingspan was a fairly standard 1.06 meters (a bit more than 3 ft), with a conventional tail style and taildragger undercarriage. Mr. Meadth tied their aircraft to the tether as the excitement mounted, and Pedro took the first turn at the controls. A gentle increase on the electronic throttle, and the affectionately named Thanos rose up beautifully into the air! Nolan took a turn as well, and the team scored two successful take-offs and two successful landings—the ideal outcome!
Plan view of Thanos, taken from the CAD model
Next up was Madison and Alena. Their Airplane Baby was ready to take its first steps, with Alena at the helm. In various shades of baby blue, the 540 gram winged wonder stretched out at an impressive 1.2 meter span (about 4 ft). Their wing aspect ratio (the ratio of wingspan to chord length) was a very healthy 12, almost double that of some other teams. But would it fly?
Airplane Baby gets ready to roll!

The girls produced a set of plans for their
written report
Without a doubt! Both Madison and Alena toured the gym in a somewhat rollercoaster fashion, the tether line being stretched to its limit. We estimated just a couple of feet clearance between the aircraft and the walls—enough to make any pilot sweat a little! But after a safe landing, all was well.
And now a little math. Replaying the video, it looks like Airplane Baby took about 3.5 seconds to complete a lap. If the diameter of the circle was about equal to that of the basketball court (50 ft), then the radius of the circle was half that: 25 ft. The speed of the aircraft through the air is equal to distance over time; the circumference of the circle divided by the time to get around that circle.
Circumference = 2π × radius = 157 ft
Speed = distance/time = 157/3.5 = 45 ft/s
This was about 36% faster than their design speed of 33 ft/s, which only goes to show that their stable aircraft design works just as well under a variety of situations. (It may also mean that their wings weren’t as effective at generating lift as theorized!)
Sam and Joshua took to the floor after that, with a slender red aircraft tied to the tether: RUBYGEM. With a planned mass of 440 grams (almost exactly one pound), this was the lightest plane on display. Their rectangular wing planform spanned 1.08 meters, and they planned to fly at only 8 meters per second (26 ft/s). A lighter aircraft does not need as much lift to stay in the air, and so for any given wing design, it can fly slower and still generate the force it needs.
RUBYGEM steps out in style
As RUBYGEM gracefully lifted into the air, it was obvious that she indeed favored a slower style of things. Completing each lap in almost 5 seconds, the flight speed can be calculated at 33 ft/s. This is also faster than their design speed, which reinforces the theory that perhaps there is more inefficiency in the design than our theory accounts for. Sounds like real life, all right!
After successful landings, Mr. Meadth made the decision to head outside with the fourth aircraft: Big Wing Boy. And boy, was it big! At over 2 meters (6.5 ft) span, this multi-colored monoplane was just too big to spread its wings indoors. It was also designed to fly a little slower, and was very light for its size: 800 grams.
Big Wing Boy, taken from the design report

There was, however, one significant issue: while the design looked good in the CAD model and spreadsheet, the greater spans and sizes meant the physical attachment of the parts was just that much more difficult. The sheer size tended to stress the wing root joints more, so extra tension lines were strung between wingtips to help hold everything together.
Being outdoors on the grassy field, the decision was also made to give the aircraft a running hand-held start, because the wheels get caught in the grass. Risky? Yes! Mr. Meadth held Big Wing Boy aloft and kicked off his shoes to get the best launch speed possible. Given that an Olympic runner travels at around the 10 m/s mark, finding the necessary design speed of 8 m/s would be a challenge!

Ben cranked the throttle to a healthy roar, and Mr. Meadth began to dash around the circle. With a final push into the air, B.W.B. lifted up into the great blue yonder where he belonged. All seemed well… and then the unthinkable! Video footage analysis confirms that the carbon fiber stick connecting the wings to the tail tore loose from the aerodynamic loads, and no plane can ever do well without that stabilizing influence. This principle was, in fact, one of the central pillars of the second semester!
The moment of horror as the tail comes loose!
The aircraft wanted to perform, but just couldn’t remain aloft. It plowed into the grassy field after only a few seconds of genuine flight. A quick repair and a repeat attempt was launched shortly thereafter, but another half-lap was achieved with similar results—with more permanent destruction this time! There was no third flight.
At the end of the day, what did we learn?
  1. Challenges are there to be overcome. The project could have modified to be easier, simpler, more virtual, you name it. But that kind of logic doesn’t get you into the history books, and doesn’t give the same kind of satisfaction. Greater levels of determination can turn challenges into victory.
  2. Theory is useful, but doesn’t account for everything. Math and physics equations and computer simulations are incredibly useful, and with high-level manufacturing can be a very good analogy of the intended outcome. But the fact is that our theoretical calculations didn’t account for a great many factors. This makes it all the more important to create robust, stable designs. The aircraft didn’t perform exactly as intended, but they did perform in the real world.
  3. Aircraft need firmly attached tails. You may want to check the welds next time you hop on board your next 737.
Congratulations to our eight aircraft engineers, and many blessings on the four seniors, now alumni: Ben, Todd, Alena, and Madison. You have completed something to be proud of!

Senior Spotlight: Alena Zeni

Alena Zeni is one of the many seniors worldwide whose last year of high school is looking quite different from what they expected. Prom has been canceled; Providence’s iconic “senior presentations” were carried out online; graduation will be a bit creative this year to say the least.

Alena Zeni, Class of 2020
Yet, while noting sadness over missed end-of-high-school memories with friends, Alena’s primary sentiment is excitement for the future—and her future is certainly bright! Alena was chosen to be an intern for NASA this summer, helping the Coast Guard design and build short-range search and rescue drones. This fall, Alena will begin her studies at Embry-Riddle Aeronautical University in Arizona, where she plans to double-major in Astronautical Engineering and Global Security & Intelligence. She hopes to eventually work for a company like NASA or as an intelligence analyst.
Alena (left) helps catch a wayward drone! (It was her
idea to use a sheet to catch it and thereby prevent crash damage.)
A student in the Providence Engineering Academy all four years of high school, it was actually an elective in junior high that cultivated Alena’s love of the subject. She admits, “If not for junior high engineering, I probably wouldn’t be where I am today!” Among her favorite memories of the high school Academy include building a Tensegrity ball (a structure made of beams and ropes in which no beams directly touch one another, but are held together by the tension in the ropes) and a hexacopter drone, affectionately named “Thiccarus” due to its broad dimensions. Alena spoke fondly of the drone, admitting that her class worked so long on the project that they personified the drone as their class “child.”
Madison, Alena, Todd, and Ben:
senior members of the Providence
Engineering Academy
A field trip to the Jet Propulsion Lab in Pasadena earlier this fall is where Alena definitively found her calling. Inspired by the work of JPL, Alena decided to forgo a mechanical engineering degree and pursue astronautical engineering instead.

Alena (upper right group) poses with her class at JPL
Alena’s senior project—a capstone experience required of all graduates of Providence that involves a research paper, professional presentation, and defense of a meaningful topic—is titled “Guy-ence and Men-gineering: Pushing Back Against Cultural Barriers for Women in STEM.” Alena gives credit to a “Women in STEM day” hosted at UCSB during her 9th grade year for raising her awareness of the gender gap in the STEM disciplines. Her interest in researching the reasons behind the divide developed throughout high school and became an obvious choice for her senior project.

Among many contributing factors for the gender gap in STEM fields, Alena cites gender-based micro-aggressions, stereotype threat, explicit and implicit gender-science biases, and the competitive, aggressive atmosphere where performance expectations are not conducive to work-life balance. To combat these challenges for women in STEM fields, Alena encourages companies to consider blind resumes in early hiring procedures, expand skills required to include stereotypical female strengths such as collaboration and teamwork, and actively ensure qualified women get deserved promotions based on merit. Alena brings her Christian worldview to her research, articulating man and woman’s equal ability to image their Creator. As image-bearers, men and women are both called to create solutions for problems that arise in the world.

Alena’s and Madison’s final project for the year

Alena’s design for her aircraft fuselage successfully printed!

As Alena wraps up her senior year, her final project for the Engineering Academy involves designing a powered model aircraft with classmate and good friend Madison Malone. The duo are assembling their aircraft and planning on flight tests toward the end of May. Alena’s love for engineering is undeniably evident as she speaks with excitement to see her creation fly, citing many late nights and Zoom calls to navigate the design process in an unprecedented classroom setting.

Her final advice to younger students interested in studying engineering, math, or science? “Don’t give up on the math. It can get really, really hard… but once you have that moment where it all clicks and falls into place, it is so worth it.”

Design, Build, Fly!

Our students can’t be together in person right now, but nothing is going to stop them finishing the capstone design/build/fly project for the 2019-2020 year. With digital tools in their hands and computer-controlled manufacturing equipment at the other end, our budding engineers, now sheltered in place, are experiencing the reality of a modern workflow. Even before the advent of COVID-19, many companies routinely collaborated from around the globe, producing advanced designs using international teams. Although not our first choice of preference, we’re taking the challenge head-on!

Mr. Meadth teaching aircraft stability via Zoom
The first step for our skillful students was to learn the ins and outs of classic aerodynamics. In January, February, and March, the eight juniors and seniors studied airfoil behavior, lift and drag equations, and learned how to use weighted averages to find the center of gravity of a complex system. Our team learned the different parameters of airfoil design, and used virtual wind tunnel tests to predict just how those airfoils would respond in real life.
The virtual wind tunnel program XFoil: a classic
historical aerospace simulation! Note the cambered
airfoil shape at the bottom, with the yellow boundary
layer on top and the blue one below
Even more important was the notion of stability. What makes some physical systems stable, and others unstable? The incredible hexacopter drone that emerged in the first semester was inherently unstable, which means that it will rapidly flip and roll and fall out of the sky if the onboard computer-controlled gyroscopes were to stop doing their job. The gyroscopes sample the position and orientation of the drone dozens of times per second, and send minor corrections to the six motors, all without the pilot on the ground ever knowing it. Stable drone flight is an astounding human accomplishment, powered by calculus and implemented by technology, but it is not inherently physically stable.
On the other hand, the powered fixed-wing aircraft in this project must be physically stable. Tethered to a central post and flying continual circles, the aircraft will have only one remote-control channel controlling the power to the motor. There are no ailerons, elevators, rudder, or flaps. Without moveable control surfaces, the aircraft must be designed to constantly self-correct all by itself. If the nose dips down a little because of a gust of wind, it must automatically seek to find level again. If it rolls a little too much to one side, it needs to roll back again. The principles involved hold true for most common vehicles: cars, bicycles, even the caster wheels on supermarket carts.
Having mastered the physics involved, the students set about the difficult task of starting their design. No kits, no instructions, no fixed starting point! In teams of two, the students created a complicated spreadsheet filled with graphs and tables and physics equations, listing masses and locations and forces and moments. The students also designed a multi-part CAD model according to those numbers using the professional-grade online platform Onshape; ideally, the CAD model, the spreadsheet design, and the manufactured plane itself will end up as three matching representations of the same reality.
Pedro’s and Nolan’s aircraft in its complete form
The same aircraft in an exploded view
Mr. Meadth ordered in the necessary tools and materials for construction: carbon fiber bars and tubes, balsa wood, lithium-ion batteries, electronic speed controllers for the advanced motors, propellers, wheels, and filament for the 3D printer. These materials were fully paid for by a generous grant from AIAA, the American Institute of Aeronautics and Astronautics. AIAA believes strongly in encouraging the work done by K-12 schools in advancing aerospace education, and Providence School has received similar grants in the past.
The delivery of the critical
components arrives!
Through the COVID-19 distance learning experience, the four teams produced their designs without ever meeting in person with each other or the teacher. Because of Zoom lessons, shared spreadsheets, and the powerful collaborative nature of Onshape, this project didn’t skip a beat. Mr. Meadth set up a manufacturing station in his own garage, and busily set to work producing what the students had designed. The CNC (computer numerical control) machine carved out flat balsawood ribs with exact length, thickness and camber dimensions, and the Raise3D 3D printer produced the three-dimensional components such as fuselages and tail.
The Providence Engineering Academy
manufacturing facility!
A completed wing rib from Ben and Todd, with
carbon fiber spar inserted
The vertical tail for Nolan’s and Pedro’s aircraft,
over nine hours in the making!
The huge 30-hour print of the fuselage/
wing box (lots of temporary support
material can still be seen

Ready for clean-up, delivery, and assembly! The
motor and one propeller option are in the background

Where to from here? The Advanced Engineering II students will receive deliveries of their manufactured pieces, to be assembled at home. Test flights, possible redesigns, and the final maiden voyages are scheduled to happen in late May—stay posted for the culmination of this exciting story!

A Tour of JPL

(This is the eighth in a series of blog articles written by the Providence Engineering Academy students. Pedro in 11th grade reflects on his experience at the Jet Propulsion Lab in Pasadena on our class field trip earlier this year.)

“The trip was really inspiring way above expectations. I enjoyed the chance to see where they work, and the 2020 rover was a memory I will never forget.”

“It really re-awoke the third grade Nolan in me. The rover around Saturn replica was cool to see, it was a great experience, and I’m so glad I got the opportunity to go.”

These are the words Josh and Nolan stated about our class trip to the Jet Propulsion Laboratory (JPL). JPL was a fun and interesting experience, and in our tour we got to learn and see things that we’ve never seen before.

First off, we saw a video that was amazing to watch. This video showed us the gigantic size of the whole universe and taught us that most of it hasn’t been explored. It also showed some satellites and spacecraft that were launched into space, and we were able to look at smaller scaled models of these around the room.

Our host shows the various scale models of historical space probes

Next, we got to see the control room, which was full of screens and numbers. This is the room where they gather information from every spacecraft, rover, and satellite. It is also the place from which they controlled the landing of the Mars rover, Curiosity, in 2012—which we learned was a really terrifying seven minutes for these hard workers! 

The control center, from which every robotic space mission
has been monitored
Then, we got to see photos from one of the rovers on Mars. These photos had been taken just hours earlier and we got to see them on a screen!

After that, we got to see the construction of the 2020 Mars rover. Amazing! We learned that anyone that is eighteen or under can get their name applied on the 2020 rover.

The rover being constructed inside a “clean room”
Our final stop was the gift shop, which sold “space” ice cream, sweaters, and some cool toys for your kids. Overall, JPL was a fun and really cool experience for all of us.

Private vs. Government Space Programs

(This is the seventh in a series of blog articles written by the Providence Engineering Academy students. In this article, 12th-grade student Todd shares why privately-funded organizations may be a better choice for space exploration.)

Space travel. It’s been around since 1961 when the Soviets launched Yuri Gagarin into space. But who has been sending people into space here in the United States? For the longest time, the National Aeronautics and Space Administration (NASA) and Jet Propulsion Laboratories (JPL) were the sole authorities on spaceflight. That all changed when SpaceX, the first private space agency in the United States, was founded by Elon Musk in 2002. Since then, there have been 76 launches by SpaceX, and 26 launches by NASA.

But what is the difference between these two agencies? NASA is a public, government-owned organization and SpaceX is a private company that has not yet launched an IPO. So which organization takes a better approach?

Although NASA has a bigger history in the space travel industry, the real facts lie in the fundamentally different ways the two organizations are run. NASA is entirely funded by the government, so it gets its money from taxes and loans the government takes out. SpaceX is completely private, so its only money comes from its own profits and money from investors.

In my opinion, privately funded space organizations are the way to go because of the way they are funded. At the time of this writing, the United States national debt is around $22.8 trillion, and we have spent around $601 billion dollars on NASA so far. This money should be spent on other things such as working on shrinking the national deficit.

On the other hand, SpaceX has not gone public yet, so we do not know their current revenue and value. Though we do not know the numbers yet, we can say for sure that SpaceX does not contribute to the national debt, which is a very good thing.

One additional factor that sets the two groups apart is the ability to reuse rockets. SpaceX’s flagship rockets are the Falcon Heavys. The company boasts the ability to reuse its rockets after they have been recovered. This is a smart, cost-saving strategy that further proves that space travel should be privatized.

Regardless of the organization, one thing is for sure: space travel is here to stay, and the opportunities are ripe like never before.

Major Project: Hexacopter Drone

(The fifth in our student blog series, written by Sam in 11th Grade, is followed by the teacher’s two updates on the project, so please read all the way down! Flight tests were finally successful, as students and teacher alike learned the hard realities of “going back to the drawing board!”)

While we don’t plan on taking him to the sun, Icarus was the name we selected for our massive hexacopter drone. With a 31-inch diameter, and the theoretical ability to lift almost two pounds on top of its own five-pound weight, it is operating at the higher end of recreational drone constraints. Most commercially available drones today feature only four propellers, and a mass of around one pound.

Early sketches of the design, with design priorities listed on the side

When we were designing “Thiccarus” we decided to push the boundaries with the materials we had available. A hexacopter design, as opposed to a more common quadcopter (a standard recreational design with four propellers), gave us more lift power and stability with a trade off on speed and maneuverability. To reduce weight and maintain strength Thiccarus would be constructed with 3D printed body parts and carbon fiber struts connecting them. However, when we were brainstorming, we decided that our drone’s primary function would be cargo delivery (despite my suggestions to make it into a fishing drone or a laser-toting drone with a search and destroy mission).

Pedro, Nolan, and Joshua tear apart
old quadcopter drones from two years
ago–fare thee well!

We came up with our design, then our constraints and requirements. After this, we split into design teams, each headed by ”captains.” After the protective shrouds around each propeller and control center base were decided upon, we set to starting a joint Onshape project. Onshape is our 3D design platform of choice for this project. Each team member was assigned one component of Thiccarus to design, and it came together well in a collaborative fashion. Each member of the design team is able to see in real time how their part will integrate with the other parts, which is incredibly helpful.

The eight students work concurrently on the drone CAD model,
with each one instantly able to see how their component fits into
the broader scope

The hexacopter design emerges!

The largest and most difficult piece to print: the central electronics
platform; five or six attempts at printing were required

Icarus is currently in the printing stage, and when it is fully constructed, it will be mounted with two cameras feeding to a battery powered LCD screen. Steered by the controller, it will be capable of flying high and low to deliver small payloads.

(Sam’s article was written in early October. After a delay in printing production due to some technical difficulties, the entire drone was finally fully assembled and taken for some early test flights. And now the update—which gets a little technical…)
After many hours of printing and assembly…

Sam, Ben, and Todd carefully attach
the motors and batteries and other
electronic components

The 8th Period engineering class proudly marched their huge drone out to the Providence soccer pitch. Gentle (and safe!) power-ups in the classroom had proved troublesome, with erratic behavior being immediately apparent. The drone was very touchy, and tended to spin around and roll to one side. Cutting the throttle from even six inches of altitude caused the aircraft to fall with a ungraceful “thump”, with small 3D-printed pieces occasionally breaking off.

Alena gave an insightful suggestion that we could take it outside and stretch out a big sheet of fabric to catch the drone as it fell. This would allow us to try to gain more altitude—and more time to evaluate its behavior and get it under manual control. The soft fall into the fabric would certainly keep both drone and students completely safe! As an added bonus, we would look comically like cartoon fire-fighters.

The group heads outside to try an initial flight: safety goggles on!

And look like cartoon fire-fighters we did! The plan worked rather well, except for Ben slipping accidentally in a mud patch on the field in his zeal for saving the drone. With the extra flight altitude and time, we learned that the machine wanted to spin on its vertical axis—absolutely out of control. Where it should have lifted gingerly into the air and hovered obediently, it was a veritable whirling dervish, and the group could not even agree on their recollection of whether it had spun clockwise or counter-clockwise!

It may look like the class is flinging it into the air—we promise
it is actually flying!

In a typical situation like this, the pilot should be able to add in some “yaw” trim. This means that the controller is set to always provide a little bit extra of yaw control, intended to counteract whatever is naturally happening and make everything balance out again. But adding yaw trim in either direction just didn’t change anything, and after one particularly wild spin the drone fell outside of the fabric and broke one of its 3D-printed propeller shrouds.

See that tilt to one side? About three seconds later Thiccarus
successfully escaped our circle of friendship!
Back to the drawing board…

  1. It is possible that the flight controller—the 1-inch small box that houses gyroscopes and inputs and outputs and magnetometers and so on—is just misbehaving or badly calibrated. But after several recalibrations and trying an alternate one that we had in stock, there was no improvement. Check.
  2. Is Thiccarus just way too “thicc”? Maybe. We could have designed more aggressively, and perhaps brought him down to 2 kg even (4.4 lb). But the specs say that each motor should be able to create up to 550 grams of thrust. With six motors in total, that’s 3.3 kg of thrust available (7.3 lb). And it’s definitely getting off the ground, even with the thrust output turned down for safety. So: check.
  3. It is possible that one or more motors are just misbehaving or getting bad signals. Tiny, threadlike wires carry the commands between the different components, and we have run into problems of this nature before. But replacing one bad cable fixed that, and simple individual motor bench tests show snappy, responsive motors that will blow your papers away from across the room.

When all else fails, Google it. Apparently, when your drone experiences untrimmable yaw, it is likely the result of not having set all motors perfectly level. In other words, one or more propellers might not be perfectly flat relative to the ground, but tilted slightly to one side. And yes, this is quite noticeable on poor old Thiccarus once you look for it. Fortunately, it can be easily solved by readjusting the four screws that hold each motor down, and putting a little “shim” on one side to nudge it up to level.

This is actually an interesting application of standard high school trigonometry. If a thrust vector is pointing straight up to sky, well and good. This is what the flight controller is banking on for its power distribution calculations. But if a motor is tipped to one side by even two or three degrees (barely perceptible to the eye), the aircraft will experience a mysterious lateral force equal to the thrust times the sine of the angle. If the motor is generating a healthy 500 grams of thrust (a little over a pound), three degrees of tilt creates 26 grams of sideways thrust (500sin3°). Small but significant—and the flight controller is not accounting for it.

Maddening: yes. Fixable: absolutely. The motors will be checked and adjusted, and Thiccarus will be bandaged up and flown again. It is also very likely that a Mark II design will surface in the second semester, with higher tolerances for motor angles accounted for from the very beginning and a lighter airframe. Less airframe weight means longer flight times, a more responsive drone, and a greater possible payload.

Providence Engineering Academy: carry on!

(Our final update for this story on the 19th of November.  Spoiler alert: it’s a happy ending!)

As promised, the motors were checked and adjusted. Ben and Mr. Meadth stayed after school and carefully placed pieces of card under this or that side of the motors to shim them up, bringing them as close as possible to vertical. Three motors were in need of adjustment, but none of them were out of line by more than about two or three degrees.

The drone was powered up, with high hopes… but the end result was exactly the same. Thiccarus wanted to flip over to the side and rotate faster and faster, and nothing could persuade him otherwise. Forget flying too close to the sun—Thiccarus couldn’t even get off the ground!

And then…

And then

Mr. Meadth had his flash of inspiration, and it all came down to this image:

The source of all problems.

This diagram shows the initial wiring and setup instructions from the flight controller. A certain teacher thought he had carefully followed the diagram; unfortunately, he had set the actual propeller directions all opposite. For example, propeller 1 was supposed to be rotating clockwise, but it had been set up to be counter-clockwise.

What’s the big deal, you ask? Well, while having everything opposite would still be balanced to some degree, the flight controller uses the spinning propellers to control its yaw. Say the craft wants to yaw to the left, it chooses a propeller to spin faster to the right (like propeller 1), and Newton’s Law of Reactions takes over. If it wants to yaw to the right, it might choose a left-spinning propeller to do that (like propeller 2). But since each and every one was backwards, the corrective actions it tried to take were in every case making the situation worse. If it started drifting left, it would end up spinning more left—a classic vicious circle if ever there was one.

A quick click of a checkbox in the computer and that was solved. All propellers: backwards. Oops.

Propellers… spinning the correct way!

You know you’re doing something
right when you’re looking at the bottom
of the drone

This portable outdoor screen receives
video input from two onboard cameras

Today marks another successful series of flights. We currently get about ten minutes of air time with two fully charged batteries. Three students plus teacher have been brave enough to fly around a little bit. No major accidents—perhaps a leg snapping off here or there with a rough landing!

Lessons learned:

  1. Persistence pays off. If this is a thing that can be done, then you can do it. Just get out there and keep troubleshooting until you work it out.
  2. This is a new era of high school education. To collaborate on a CAD model, 3D print it, order the electronics, and create a hovering 2.2 kg monstrosity in the space of three months is just not something a school could have done in-house ten years ago. Truly these are amazing times!
  3. These students are capable. With the right leadership and direction, they know how to think and problem solve and calculate and design. They will go far.
The story ends here, but keep an eye out for Mark II! We just can’t resist. There are already so many things that could be optimized (chiefly, stronger airframe and lighter weight). Lighter weight means more air time, so bring it on! Look out for Son of Thiccarus in the second semester, and until then, stay posted.

Gliders Launched!

There was a mixture of feelings in the Advanced Engineering II class last week, as they put the finishing touches on their gliders. These thirteen students had conceived, planned, and brought forth finely-tuned creations over the past nine months. The thought of now—literally—throwing them to the wind was somewhat concerning, to say the least.

Aaron throws his team’s glider from the roof to the field

Aaron, Caleb, and Megan had worked on a design with the shortest length from nose to tail, which resulted in the lowest weight of all four teams: 281 grams (a bit more than half a pound). They pulled cellophane over 3D printed ribs to create an aerodynamic lifting wing, and they opted for a balsa tail and body, connected by two carbon-fiber rods. Their team was also the only one to decide against undercarriage, relying instead on the rounded fuselage itself to land safely on the grassy field.

In total, this smooth sailplane made about four throws, with some repairs along the way! Sporting flashy silver and gold control surfaces, they reached a maximum distance of 68 ft. It also bears mentioning that the cumulative report with the conceptual and detailed design, plus appendices, came out to a whopping 23 pages. Well done!

Megan, Aaron, and Caleb standing proudly

Kylie, Luke, and Josh had the great honor of building the largest plane, dubbed by some The Spruce Goose. Click here for some serious aviation history behind that name! With a wingspan of 100 cm, a chord length of 22 cm, and a total nose to tail length of over 80 cm, it took to the air for an historic maiden voyage, with Luke at the helm.
Unfortunately, things did not fare so well for this 502 gram glider (a little more than 1 lb), which only made it 17 ft out into the field. Mr Meadth also tried his hand at throwing this one, but this was hampered by some sticky undercarriage. The good news is that the egg onboard was well protected!
Kylie proudly holds the Goose aloft

Luke, showing some signs of stress before the big throw

Left to right: Colby, Mikaela, Tys, Victor, Luke, Kylie, and Josh
Next in line was the Banana Grinder, so named in honor of some typographical errors early on in the design process. Tys, Mikaela, Victor, and Colby also chose to pull cellophane over printed ribs, but decided to rely heavily on the CAD skills of Tys and Colby to construct many other components of the aircraft, resulting in a high construction precision.
Colby and Tys did great work on matching the CAD model
to the real thing

The team worked powerfully together to build a sleek-looking machine. Others commented on the slender, low profile, the extensive use of carbon-fiber rods in wings, tail, and body, and Mikaela’s cover page artwork! The Grinder’s best launch took it an impressive 60 feet.

Colby waits for the wind to pass before making the throw

Our final team boasted several different features not seen on any other glider. Blue Wonder was the only glider to have a dihedral angle (where the wings slope upwards), it was the only one with a T-tail instead of conventional, and it had the longest wingspan of 120 cm, resulting in the highest aspect ratio. Aspect ratio is a comparison of the wingspan to the wing chord. The students had been taught in class that a high aspect ratio would lower the induced drag. Other teams had aspect ratios around the 4 to 8 mark; Blue Wonder was 12.6.

Eva, Gabe, and Claire also made extensive use of 3D printing and carbon fiber, much like Banana Grinder. Finally, they chose to skin the wing with tissue paper soaked in dope (a kind of glue that dries hard and pulls the paper tight). This resulted in a smoother, tougher lifting surface compared to the cellophane. Click here for the CAD model of their components.
The completed 120 cm wing and T-tail (not yet skinned), connected
by a carbon-fiber rod
It is an unfortunate fact of history that the maiden voyage of this aerial acrobat was a complete disaster. After several successful short-range tests, Gabe hurled the machine into the air… only to have it bank around to port and crash violently into a row of bleachers! With a total distance of only 4 ft and a broken tail, Claire brought out the masking tape to get it ready for another flight.

Gabe hefting the Blue Wonder down on the ground

A second throw left the crowd speechless, as the Wonder curved gracefully into the breeze. After gaining a dozen feet of altitude, it swooped down across the field, showing none of its port-side tendencies, and landed smoothly at 97 ft! Gabe and Mr. Meadth were both able to make a few more flights just as successfully before a few rough landings left it crippled and grounded like the others.
At the close of the experiments, Victor commented that he would never look at an aircraft the same way again; he now sees the c.g. and the balance and all of the work that went into it. And needless to say, Eva and Gabe and Claire were glowing with pride.
So—what was learned?

  1. It is better to have high accuracy construction, which 3D printing perfectly lends itself to.
  2. A dihedral wing angle really does promote roll stability.
  3. The planes’ distances were directly linked to their wing aspect ratios (how slender they were).
  4.  Lighter planes flew further and better.
  5. The doped tissue paper seemed to lower the drag compared to the cellophane.
  6. Carbon fiber really is as awesome as it sounds.
With only a few weeks of school left, the students are now turning their attention to a special project, funded by a grant awarded by the EnergyPartners Fund. Broken out into five new teams, they are assembling electronic components for a quadcopter drone. They will design and 3D print the body of the drone, holding all the pieces together. More to come!

Gliders: In Production!

A quick update on our Advanced Engineering II glider project: the students are currently hard at work translating their theoretical calculations into hand-made reality. The problem is at first daunting; how do you create the various parts of a flying machine, according to a specific design? There are dozens of materials that might be chosen for each component, and the production needs to be accurate enough and cheap enough and quick enough and repeatable enough!

Aaron lines his twenty ribs carefully
in place, ready to glue

All teams have settled on a 3D-printed rib-and-spar design for the wings, although the exact rib profile varies in size and shape. All teams are using carbon fiber square tubes for the spars (the long beams that run through from wing tip to wing tip). Some teams are planning on skinning their wing with cellophane, and others are planning on tissue paper and dope (a kind of glue that tightens and hardens the paper).

Kylie and Josh and Luke are producing
the largest, thickest ribs of all teams
(sounds delicious, in fact)

To see some interactive CAD models that Tys and Mikaela and Colby and Victor are working on, click here.

Other components, such as the undercarriage and fuselage and tail, are being made from 3D-printed parts, balsa sheets, more carbon fiber, and even colorful pipe cleaners.

Victor, Colby, and Mikaela go over the particulars of their CAD
model with Dr. Nathan Gates, retired aerospace engineer

Megan and Caleb receive valuable
advice from our classroom mentor

To help with the design process, we asked retired aerospace engineer Dr. Nathan Gates to visit our classroom. Dr. Gates moved around the different teams to consult with them. Each team explained their design, and received valuable feedback as to their construction plans. Dr. Gates’ area of expertise was structural mechanics; he was doubtlessly overqualified for this role!

Proud Providence alumna Willow looks over Gabe’s and Eva’s
wing design

To further sweeten the deal, we also asked Willow Brown, Providence alumna (2015), to come by on the same day. Willow’s sister, Kylie, is on a team with Luke and Josh. Willow is currently studying mechanical engineering at Loyola Marymount University. Did this give Kylie and her team an unfair advantage? Only time will tell.

The maiden voyage is fast approaching, so watch this space. There’s more coming up later this year, too—students will design, print, and build quadcopter drones. Stay posted, and thank you to Dr. Gates and Willow!

In the Steps of Orville and Wilbur

The Advanced Engineering II group has a unique and challenging task in front of them. In fact, it is quite possible that none of the students has ever undertaken something quite like this: a group project that lasts from September to March—designing and building a model glider!

The students have been hard at work learning the fundamentals of aerodynamics, as applied to conventional aircraft. They understand Bernoulli’s principle, the momentum shift theory of lift, what induced drag is, and why most modern aircraft have those little turned-up ends on their wings. They know the value of the theoretical lift curve slope, and how much lift an uncambered airfoil produces at a zero angle of attack, and they can check it all in a virtual wind tunnel test! Impressed yet?!

Luke (11th) and Kylie (12th) consult their extensive course notes
as they work on the detailed design spreadsheet

Divided up into four teams, the students have just put the finishing touches on their complex design spreadsheet, which describes in precise detail the various features of the glider they are going to build. Each glider will be thrown from the top of the science lab building onto our field, carrying a single (unboiled!) egg to safety as far downfield as possible. The plane that successfully flies the farthest and lands safely wins!

Tys (12th), Victor (11th), Colby (11th), and Mikaela (12th) happily
nearing the end of their design calculations after several weeks

The students will be using a variety of materials and techniques; we are currently amassing a stockpile of carbon fiber tubes, balsa wood pieces, tissue paper, cellophane, lead weights, aluminum wire, and other bits and pieces. The teams are creating CAD models of their wing cross-sections, intending to 3D print them in the coming weeks. Most of the gliders are about three feet across the wingspan, about two feet long, and weigh a bit more than half a pound. (By the way, all of our work is done in metric units, to be in keeping with international physics standards!)

In order to get a real hands-on feel for the work, the group also took a special visit up to the Santa Ynez Airport, where they were shown a variety of gliders and powered aircraft. This was the perfect chance to connect theory to practice, and it no doubt helped inspire the students as they move into the manufacturing phase.

Josh and Gabe look at the cockpit
of an older glider

Dave and Colby, employees of the airport, graciously showed us around the couple of dozen light aircraft sitting on the runway, answering student questions about wing design, gliding techniques, and the pilot license process.

Megan and Caleb dreaming big as they stand by another one of
the gliders
The students look on as Colby describes the sleek and elegant
Cirrus light aircraft

As more airplanes took off and landed around them, the students got up close views of a shiny Cirrus, many older Cessnas, and an unusual-looking Long-EZ. Colby described to us the great thrill of flying, being in perfect solitude up in the sky; he is working towards his powered pilot license.

Is it a spaceship of some sort? The Long-EZ design is not
recommended for the students to imitate for their glider design

The class’s six seniors from left to right: Tys, Mikaela, Caleb, Megan,
Aaron, and Kylie; our guide Colby on the right
With plenty to fill their heads about glide paths, turbulent flow, night navigation, wing construction, parachutes, and fuel pods, the students took one final pose on an aircraft they were allowed to sit in! Thanks very much to Dave and Colby and all of the crew up at Santa Ynez—perhaps we’ll see you again sometime soon! Airport Day is coming up on Saturday, May 20th, and all are welcome.