Thursday, May 30, 2013

Floyd Richards - Mentor / Friend

In past blog posts I have mentioned one individual that taught me more about model aviation than anyone else and also was a big inspiration for me to teach others what I had learned. His name was Floyd Richards. In my post about indoor free flight I had mentioned how someone had given me Floyd's name to contact after they had seen me flying a rubber free flight airplane at the local radio control field. We would not only fly indoor free flight, indoor radio control, and radio control soaring together but would also have lunch together on occasion. When I needed a little help on some model airplane problem he would invite me over to his shop and I helped him with computer problems.

Floyd Richards Surrounded

AMA Cub Scout Event

Floyd was a retired engineer when I met him; he was very detail-oriented as well as a perfectionist. Sometimes his was manner could be seen as slightly odd, but I embraced his brilliance. The only picture I could find of Floyd was him helping at an AMA Cub build for a group of cub scouts.  Floyd was good at helping kids but it was really not his deal. He would was wonderful with helping me to a point but expected that I would follow through and complete the task, as it should be.

Floyd's Gentle Lady Sailplane in Flight

Floyd got the use of the local armory for indoor flying and at one time had modelers from surrounding cities coming to fly in Winona. Even though most were flying indoor RC airplanes he would convince them to build a certain free flight rubber plane for an informal contest.

Floyd Sold me Camera Plane

When Floyd moved away to be closer to family we continued to email on a regular basis. He always wanted me to come and visit but I always felt I was too busy with something. And then it was too late.

Sailplane Floyd Sold me to Get me Started 
Floyd Appears in this rather poor quality video and almost gets hit by a landing airplane:

Related Blog Posts

Bill Kuhl

Tuesday, May 28, 2013

Magnetic Switch Motor Kit

Having struggled to design and build my own 2-pole electric motor I purchased four motor kits from Kelvin. The first motor I constructed was one that used a magnetic switch, there are no brushes used in this motor. Also somewhat different is that there are four magnets mounted to a disk that the motor shaft goes through in the center, two coils are outside of this. To connect and disconnect the electrical connection is a tiny magnetic switch. The magnetism of the permanent magnets closes the magnetic switch as it comes near. A tiny arc of electricity is visible as in the center of the switch as the motor runs. It sounds good in theory but I wondered why five of the magnetic switches were included, the first one only lasted a few minutes of running so now I know why.

What impressed me with this kit was that it was created from thick plastic, this makes for a good bearing surface for the motor shaft to run through and the structure is very rigid. Plastic parts are glued together but the instructions did not specify the type of glue to use. I used CA and then an accelerator spray to set the bond which made a mess of the motor appearance.

Motor is Running

One thing I learned is that in the 2-pole motor I had built most likely I did not wind anywhere near enough wire on the coils.  When I unwound the wire in the kit I had wire strung out all over the house, what a mess. The total wire length must have been at least 50 feet. I had also been trying to find a "soft iron" core but this motor uses a couple of small bolts for the core.

Magnetic Switch

Directions for the motor could be better but I did get it working. The magnetic switch is on a slider plate so you can adjust the position for best performance. Sometimes the motor would quit running and sometimes it took a few tries to get it started. Then it would not start at all so I replaced the magnetic switch. I do not see this motor listed on the Kelvin website today, so not sure what that means.

Look forward to more reports on the other motors I purchased.

Bill Kuhl

Friday, May 24, 2013

The Evolution of My Mousetrap Car Design

If there is a kit available for a project, to me it is worth it to purchase the kit. Buying the first Doc Fizzix mousetrap car gave me a familiarity with a working design and something to guage the performance of the mousetrap cars I would design. For my first design I tried some rather different ideas in that the car was constructed from bamboo skewers and used cottage cheese container lids for wheels. This car worked pretty well but the lids can warp from heat and the bamboo structure required additional bracing because the car was twisting. It was my determination that this design would not be ideal for students to build for their first mousetrap car.

My Start with Doc Fizzix Basic Kit

My First Mousetrap Car Design

Current Design I Use for Classes

My next series of mousetrap cars were constructed in a more conventional way from balsa wood and using four CD wheels with faucet washer hubs. This car was used for a College for Kids class and worked pretty well except the lever arm constructed from balsa glued to form a T-structure was not strong enough for kids to handle. Also the faucet washers I had bought in a hardware store did not fit the hole in the CD tight enough.

Balsa Car Used for College for Kids
Balsa Lever Arm Broke for Students

For the next year I used a heavy dowel for the lever arm and I came up with the idea of cutting chunks from tarp straps for the wheel hub. The dowel lever arms did not break but the students had trouble attaching the lever arm to the wire on the mousetrap with hot glue and string. For this summer's class I have the lever arm already attached. Hot glue takes sometime to setup solid, for impatient kids this is a problem. Since last year's class I have also created the chassis for the car from foam cut with a hotwire.

Hub Created from Tarp Strap

Much can be learned from struggling with a design but for a class where there is limited time and no one to help assist the students I find it better to refine the project.  It is my hope that the students will be inspired to create their own mousetrap cars if the first one was a good experience.

Axles Cut from Coat Hanger - cheap

Screw Eye Idea Came from PITSCO Solar Car Kit


Doc Fizzix Website
My Mousetrap Car Article
Quicky Mousetrap Constructions Article

Bill Kuhl

My Experiments With Air Rockets

My article on Air Rockets probably has more value in demonstrating how a simple idea can be experimented with in so many ways than the construction portion of the article.  Like many of my projects I find inspiration in a purchased item and then try to figure out how I might be able to build something like that inexpensively.

Inspiration to Build Air Rocket

First Air Rocket Prototype

An air rocket uses only a blast of air to propel it skyward, no water is used.  On the simple systems, there is an air bladder that you step on real hard and this supplies the blast of air. My biggest challenge was finding a bladder that would not crush or burst when stepped on. Many people use a 2 liter plastic bottle but I found that crushed too easily.  I also tried to construct my own bladder using spongy foam wrapped in plastic. This worked for awhile but eventually with enough jumping on it, a holes would would develop in the plastic.  Another idea was to use a plastic plunger that had a fairly large air chamber, this just did not supply enough force to launch the rocket very high.

Crushed 2 Liter Bottle

Heavy Plastic Bag Blew Out Easily

Building Air Bladder with Foam

Rocket & Bladder I Built

A science teacher friend suggested a boat fender, the plastic thing that goes on the side of a boat to keep it from scratching on the dock.  This cost a few bucks but worked perfectly, it would not burst and had the elasticity to come back to shape after every launch.

Plunger from Hardware Store

Drilled Hole in Waste Basket to Hold Plunger

Boat Fender Air Bladder

I still wanted to get higher launches so I took a new approach in constructing rockets, instead of the foam tube for pipe insulation I built rockets out of heavy paper. The resulting rocket was much lighter and had a smaller diameter tube. Paper rockets were quick and cheap to build so when a rocket looked shabby, it was easily replaced.

Paper Air Rockets

Bill Kuhl

Thursday, May 23, 2013

Yet Another Water Rocket Parachute Fail

If you have been reading my blog or website you might have noticed that I do not give up real easy when faced with an engineering challenge. Getting reliable parachute deployment has been an issue for many people that experiment with water rockets. I would like to find a simpler method than using a windup mechanism but I do not know what it would be. Some people have gone to electronic devices but I sure would like a simpler and cheaper solution.

Large Plunger on Rocket to Push Nose Off

After some success with my first rocket that used the windup mechanism that held back a compression spring and pushed a rod upwards to push the nose off, I thought that idea could still work with modification. My thought was if the push upwards of the nose cone had a longer stroke and more force behind it the nose would have to come off.

Two Tension Springs Pull Pushrod Upwards 

Two accomplish this I used two springs under tension that pulled a rod up from inside the cottage cheese container that was part of my rocket. To make sure this great thrust upwards would always be pushing on the nose cone I created a round disk and then four dowels attached to the disk pushed against a ring inside the nose cone. The windup mechanism pulled a short string connected to a catch mechanism that held back the springs. Worked great on the ground.

Disk Removed to Show Mechanics

My theory of why it did not work in a real launch is; I believe that even though the nose cone was forced off, the force of the air at such high speed was pushing the nose back down. It almost impossible to know because everything happens so fast and the rocket is so far away at apogee. Examing the rocket after it crashed was of little help because it was broken so badly.

Four Dowels Push Against Ring

After three prototypes of the push off nose I decided it was time for a whole new approach which started my experiments with the side deploy parachute. To me this is rather ugly but it has been reliable after several test launches.

Bill Kuhl

Wednesday, May 22, 2013

STEPS for Girls Summer Program 2006

I was reading a small article in Model Aviation magazine in 2006 that described a summer program for girls 12 years old at UW Stout in Menomonee Wisconsin that was based on building radio control sailplanes as a manufacturing process. I was very interested in radio control sailplanes at the time and the idea of using model planes in an educational setting was even more interesting to me.  Stout is about 70 miles from where I lived so I emailed the director of the program Pete Heimdahl and he invited me to come over for a day to observe.
Starting Small Engine on Completed Glider

Cutting Foam Wing with Hotwire

Picture of Shop Area
Finished Gliders

On arrival I was given a tour of the facility where the model airplanes were manufactured.  The process was not like how model planes were normally constructed but consisted of a bunch of stations for each small process need to complete a model sailplane.  Each girl would travel through all the stations to build the sailplane like on an assembly line except that the builder would learn all the different station operations and not just one operation.

CAD Class

Flight Simulators

Robotics Class

The glider was constructed mainly from the foam board that is sold in art stores and the wing was cut using a hotwire. There were many jigs setup for the construction, every plane should be the same as all the rest. An entire glider was built in a day and then all the gliders were flown in one evening, I stuck around for the flying which appeared to be a real thrill for the girls. I also went to classes that were also part of the program like robotics, computers, and CAD design.

Launching Another Glider

Flying the Glider

I also created a video that explains this better. The program has been held at other universities such as St. Thomas in Minnesota. At Stout the focus has changed from the model airplane to a model boat and this summer it will be building a robot.  The fall of that year I would return to show people at Stout the idea I had for an electric powered airplane that had the electronics in a removable pod like the gliders they were building. In this way many airplanes can be flown using a few radio control units.

Radio Pod Switched Between Gliders

Most impressive to me is that this program continues after many years and data has been collected proving that when entering college the girls that went through STEPS were much more likely to study in a science area than the general population of females.  The video explains this in more detail.

Bill Kuhl

STEPS at UW Stout
STEPS at St. Thomas

Tuesday, May 21, 2013

Simple Catamaran Sailboat Model

One project I never did create a construction article for was a simple model catamaran constructed from foam, craft sticks, wood dowel, a plastic bag and pop can material. I had started building a Dumas catamaran kit that I thought was really difficult to construct; it would be fun to build a simple catamaran model. No doubt it would not be as efficient but it still would be fun to experiment with. The boat has worked well but I have been hesitant to publish a construction article because of the dangers of water and small children.

Simple Model Catamaran Sailboat

To build this boat I started by cutting out the pontoons from foam in a teardrop shape and fastened them together a few inches apart with the big craft sticks that look like tongue depresses. I used hot glue which holds up to water for awhile but after some dunking it did come apart in places.  The sail was just plastic cut from a plastic bag.

Rudders from Pop Can Material

The first test run I attached a fishing line to it but there were no rudders on the boat. Like I had thought it would not sail in a straight line and would move every direction. For the next time out I created rudders from pop can material cut and flattened in a rudder shape. Paperclip wire fastened a rudder to each pontoon.  This was a big help and the boat would sail straight with just a slight breeze. With the fishing pole I could let it out and reel it back .

Sailing Free on Lake Winona

Sailing on Backwater of Mississippi River

On a couple of occasions I took the model catamaran with me in my kayak and let it sail without the line attached. One of these sessions the wind was fairly strong and little sailboat was moving pretty fast. It did tip over once when it caught a strong gust. There was no ballast in the bottom of the pontoons which might help.

Gust Caught It

Bill Kuhl

Monday, May 20, 2013

Water Rocket Pendulum Parachute Recovery Idea Fail

Yet another idea I tried for parachute deployment that didn’t work for me. The theory I had was that with enough weight hanging down on a pendulum it could keep a shaft holding stationary but as the rocket begins turning horizontal at the apogee a catch that was holding back a vertical piece from the shaft would release as the catch position changed. Hopefully the pictures I provide will explain this a little better.  There was a spring over the horizontal shaft that pushed the shaft to one side which released the nose of the rocket that had tension on the opposite side from rubber bands.

It was another one of those prototypes that appeared to work fine in a slow motion test on the ground but not so well in a high speed launch.  One good thing, I really got a nice picture of the liftoff of this rocket. The parachute did come out, trouble was it was only about 35 feet high when the parachute deployed.  How the parachute deployed was the forces at launch caused the mechanism to rip out where it was fastened and this pulled in the pin that was holding the nose on the rocket.

Mechanism to release pin holding down rocket nose

At first I was tempted to try to repair the damaged parts but the more I thought about the idea I thought there must be a reason I had never seen anyone else try this method.  The amount of weight that I had on the pendulum was more than I had thought I would need also.  With less weight it would not activate and retract the pin holding the nose down.
Ended up with so much weight on pendulum

Yes, another failure but I still think I learned something and had fun trying.

Rocket came down fine

This video explains why the idea could not work:

Bill Kuhl