Friday, March 25, 2016

Google Trends Might Not Figure Out STEM but Can Spot a Wrecking Ball

Recently I did some web searches using the Google Trends web utility because I was curious what search data might show for terms related to the projects on my website and STEM education in general. My observation from the summer class I have been teaching is that the interest has diminished somewhat over the last few years although the traffic to my website is higher than it has ever been. Increased traffic to the website no doubt can be correlated to adding new material and my social media efforts to relate back to the website.  Locally I have not done any promotion of my website or projects for some time so that could explain some of the local decline.

Data provided by 

To use this free web utility just bring up . I noticed the information Google provides says “a percentage of Google web searches are analyzed”, I wonder how much that might detract from the accuracy?

I started searching for the acronym “STEM” but in the suggestion of search terms it was suggested to
use all the words, Science Technology Engineering and Mathematics. There is a good reason to do that because just entering STEM could give results related to stem cells. I ran into this issue when I typed in “kites” and so many results came up for one month in 2010, turns out there was a movie by that name released around that time which spiked the results.

In demonstrating this utility to a friend I picked out someone with some celebrity status, “Miley Cyrus”. It was interesting to note there was a big spike in August 2013, my friend said that was the time Miley had come out with her song and video “Wrecking Ball”.  To verify this theory I entered “Wrecking Ball” and darn if the spike appeared in the same time segment.

Back to my searches related to STEM and project ideas; STEM spelled out the graph is pretty level until 2011 then it starts going up. September 2013 there is a huge spike and then it goes gradually up. “STEM education” starts a gradual climb upwards in 2007 until a peak the goes up and down until the present.  If anyone has ideas what has caused these trends, leave a comment.

What has been more puzzling to me is searching on the different project areas such as mousetrap cars, syringe hydraulic arms, and water rockets have shown a decline and then leveling off in recent years. As far as a spike in for STEM in 2013 there was a (STEM) Education 5-year Strategic Plan published in May 2013 on the Whitehouse website.

Wednesday, March 23, 2016

Calibration and the Free Flight Model Airplane

In recent months I have been experimenting with the Lego NXT robotics that I had purchased a few years ago. My focus lately has been to learn the different methods in algorithms for following a black line on a white background. Simpler methods work but result in a somewhat jerky path around the black line track.  Then I tried a program that starts with a “self-calibration” before going around the track and the performance was amazing, it followed the path really smooth and much faster.

Lego NXT Following Black Line Around a Track
Quadcopter Must Calibrate to Ground Below

This had me thinking about the definition of “calibration” and all the different places this idea is used. Calibration is adjusting to known or unvarying measure. Quadcopters do this to figure out what is level in relation to the ground below but what about some areas that are not so high tech? How about when you tune your musical instruments by comparing to a few notes on another instrument that is in tune? My mind then started thinking about free flight model airplanes and selecting the launch position and adjusting the power phase of the flight. During this process you are adjusting to the flying conditions at the time, would this be like a calibration process.

Rubber Powered Free Flight Should Drift Away from the Trees

For a free flight model airplane instead of using electronic instruments to record data such as light levels or distance from the ground you most likely will just feel the wind on your face to determine where to launch although contest flyers might use electronic devices for thermal detection. As the model plane normally will drift with the wind you will want to position yourself far upwind in the field boundaries. The velocity is what is important; in the physics definition, velocity is a combination of speed and direction.  Where the free flight airplane lands downwind normally results from the direction the airplane drifts and the speed the wind is blowing. In strong wind the airplane will normally drift farther.

Electric Free Flight Should Land Before Trees in the Background

If it is windy you will position upwind as far as possible but further adjustments might be possible to shorten the length of the flight. For rubber powered models reducing the number of winds should shorten the length of the flight. If it is a glow engine or electric powered model the timer that shuts off the length of the power at a time period is what you adjust.

Until the flight has ended you really do not know what to expect although experience in similar conditions will give you a better idea. I start out adjusting the length of power run to be really short and gradually lengthened as I observe how far down the field the airplane lands.

AMA Maxi Jr Launch

AMA Maxi Jr Path Changed and Landed on this Roof

The real life scenario of flying a free flight model airplanes outdoors is so much more complicated than this in that the air movement can quickly change, velocity (direction and speed) and the airplane can change course and fly a different direction. Thermal air currents cannot only take your airplane much higher but also change the velocity of the wind on the field. For this reason I normally fly my sport free flight model without dethermalizers early morning or evening when thermal activity is less prevalent. 

Indoor Free Flight Launched Close to Wall

Flying a rubber powered free flight indoors hopefully the amount of moving air will be very minimal but still there will be adjustments needed to best utilize the flying space. Based on the minimum width and height of the flying area you will need to adjust the diameter of circle that the airplane flies and have the airplane circle to the inside of that edge.  The maximum height the airplane can obtain will be limited by the ceiling height. If it is a smooth ceiling some bouncing from the ceiling might be alright but if there are rafters that the airplane could be caught in it is preferable to avoid letting the airplane climb over a certain height. Fewer winds can be used in the rubber motor but more common is to use a smaller width rubber strip or a different propeller.  

Sky Bunny Almost Landed in the Lake

Calling the launching of free flight model airplanes calibration might really be a stretch in that values are not normally measured and the values can vary a great deal. Yet I think my general point of the article is valid in that before launching a model airplane that flies completely with no control from the ground it is important to think about the factors that could influence the flight and adjust accordingly. With practice hopefully your human algorithms will be refined.

Bill Kuhl

Related Links

Basic Quadcopters   - my webpage

AMA Maxa Jr Perfect from the Start

Pushing the Edge with Small Field Free Flight

Monday, March 14, 2016

Good Flying for Winter Build FF Gliders

This winter I decided I would build free flight gliders instead of the stick and tissue rubber powered free flight air planes that I had built other years. I started off with a simple kit the Mini Flash, I had built one before but converted it to catapult launch. To try something different I covered the wing with Monocote which was mentioned on the plans for ding resistance. Another hand launch glider was the Boweevil a larger glider, this one I wiped on spar varnish and then spray painted the tips for visibility.

Scout CLG and Dynomite TLG Stan Buddenbohm


The other two gliders I built were the Scout CLG and a tip launched glider Dynomite both kits from Stan Buddenbohm. Before winter really started I flew the Scout Catapult Launch Glider without finishing it, I was amazed for such a simple design how well it flew. Both of these gliders are featured in a DVD available from the National Free Flight Society, “ How to Build and Fly Catapult and Tip Launch Gliders” .  I plan to write about each glider in future blog posts.

Boweevil HL 

Last Saturday was relatively warm for March in Minnesota and the wind was light. Further adjustments are needed on the Dynomite and the wing broke loose from hitting the ground after a stall. I started launching the Boweevil and after a few throws it connected with a thermal, it kept circling while slowly moving across the field. Thought this might be the last time I saw this glider but it came out of the thermal before getting to the edge of the field.

As I walked upwind I noticed a father and two kids were trying to fly kites. As there was little wind, it was not going well for them. Remembering I had a Fantastic Foam Flyer airplane in my car so I gave it to the father and gave them a quick lesson on the basics. The kids were having so much fun with the airplane but I think the father was having more fun with the rubber powered model airplane.

Mini Flash HL

After they left I made some flights on the Mini Flash hand launch glider. With the Monocote covered wing this glider is a little heavy but it sure launches nice. A few good throws and the tiny glider was bouncing around in a thermal. The more circles it made the faster it went and before reaching the edge of the field it went into a steep spiral dive that stuck it into the soft ground. After pushing my luck so many times without losing a glider I thought giving the Scout a wimpy catapult launch it would be too low to be captured by a thermal. Wrong it started circling higher also but popped out of the thermal.

Mini Flash Survived High Speed Dive

At this point I really, really had pushed my luck and decided to take my winter glider fleet home. 

Bill Kuhl

Related Links

Fantastic Foam Flyer - Rubber Powered Free Flight Airplane

Thursday, March 10, 2016

Variety in Model Aviation Hobby

“Variety is the spice of life” is a popular idiom and is how I pursue my model aviation hobby. Many people tend to limit the hobby to just radio control model airplanes or just free flight models or possibly a narrow subset such of either type.  My start in model flying was control line glow powered models which I would like to try again with electric power someday.

Diving RC Slope Glider Over a Windy Ridge is Fun Now

Some people probably limit the type of model airplanes just because that is where their interest lies.  There could be a huge number of other reasons also for limiting the type of model airplanes they fly such as flying sites, time available, help available, vehicle to transport, or money.  If competition is your main focus in model aviation then most people will probably achieve greater success if their effort is more focused.

Gas Powered Airplane Would not fit in my Small Car Now

I have tried many types of model airplanes over the years and currently do not fly many of those types of models at all.  After becoming fairly competent at flying glow powered radio control trainer aircraft I took up pylon racing with glow powered engines of the .15 cu in and later .049 because the club I belonged to hosted these events. Later my father and me designed and built large gasoline engine powered models.

RC Thermal Soaring Contest

After taking off ten years from the model aviation hobby when I started flying again I wanted to try something different so I looked into RC soaring which is my primary focus now. At the same time I built a simple rubber powered free flight which lead me to find another local modeler that was an expert in indoor free flight which I pursued also.

Flying an Indoor Free Flight

100" Span Balsa Glider

I have to believe that an exposure to a variety of model aviation activities can help you develop skills that can be helpful in completely different areas of model aircraft. For example after building delicate indoor free flight models you get a feel for handling delicate structure without breaking it.  When I built a 100” span balsa RC glider last year handling the larger balsa pieces was really easy.  Flying RC gliders from small slopes has really shown me the differences extra drag can make and the need for flying smooth. Using minimal control movement is equally important when thermal soaring RC gliders but flying close to yourself on the slope it is much easier to see what the glider is doing.

Lately I have been giving more thought to how I would like to divide the time and effort I put into my model aviation hobby

*  RC thermal soaring – many people in my area fly this and hold contests
*  RC slope soaring – great for windy weather and group trips
*  Free flight sport flying – great for flying in the evening when wind is really low
*  Promoting simple free flight models – I have been most active in promoting models constructed primarily from foam plates for kids.

Building E36 Electric Free Flight

For the future I would like to pursue outdoor free flight competition more and try electric powered control line.

Bill Kuhl