Thursday, August 28, 2014

Tiny Bubbles for Finding Thermals

Forecast the other day was for afternoon wind speed of only a couple of miles per hour; I just had to take vacation and do some model airplanes flying. Besides I had a new toy to try, a Bubble Shooter. My hope was to release a barrage of soap bubbles and I would see the bubbles quickly rising in thermal air currents, not a new idea for sure but something that I had not tried yet.

Tiny Bubbles Find a Thermal for Me

Sky condition was partly overcast much of the time but the sun would peak out also, the wind was indeed light. I was launching my efficient radio control sailplane the Allegro Lite from a short hi-start and I just couldn’t find much for lift. It sure gave me a lot of practice launching and landing but thermal lift strong enough to climb in seemed rather elusive. After a couple of hours of flying only a couple of times there were flights where there glider was climbing in thermal lift. The last time I tried to video with my GoPro camera and started to go into a dive. Flying and holding a camera doesn’t always work so well.

Launching Soap Bubbles

Bubble Shooter

Launching the bubbles I was not detecting much thermal action either, most bubbles would just travel horizontally along the ground with only a couple of bubbles actually starting to rise very high at all. The true masters of the thermal were having trouble, I spotted a turkey vulture that would only make one circle and have to start flapping it’s wings.

Holding Allegro Lite Sailplane

Wind Speed was Low

To test the air further I had brought along a couple of simple rubber powered free flight models. One of these planes is kind of a cross between a Denny Dart and a Squirrel. Tail was Denny Dart but the wing was flat with ribs curved in a form and winglets for stability, it is a good flying plane but the covering was ripped in places.  I wound in some turns and launched this plane, it started to climb like crazy, it had found one of the elusive thermal air currents. 

Rubber Model Found

Model Traveled From Way Back

Spotted on Top of Weeds

Flying With the Birds

Tried to take video of the plane probably about the time the rubber wound down but it was much too far away to see anything on the video. The video recorded for slightly longer than one minute so I am guessing the flight was around 1 ½ minutes. I chased the plane across a good distance of tall weeds but it was easy to find.  Tried the rubber model three more times to see if it would again find thermal lift but the flights were shorter; 52 seconds, 45 seconds, and 36 seconds. On one flight a bunch of birds joined it in flight.

Bill Kuhl

Tuesday, August 26, 2014

UMX Radian for Thermal Flying

After dinging up my UMX Radian from slope flying from a concrete wall with iron posts I decided I would purchase another UMX Radian to use just for thermal flying and try to keep it in near perfect condition. After picking the new glider up last week and quickly sliding the wing in, I went out flying. Lately I have been on a quest to find more types of places that I can fly this glider from.  There was a small park on top of a large hill that came to mind but there was no parking close by.  Not far from there was an empty lot in an area of new construction, it was on the edge of a hill so I thought maybe thermals would come up the hill or there would be slope lift farther out.

New UMX Radian

Flying at One Edge of the Vacant Lot

The highlight of flying there was that the little Radian caught a thermal low right in front of me that I was able to keep the glider in for the perfect corkscrew path upwards to a climb that was fairly high for a small glider.  As it was drifting over trees near an area of active construction I headed the glider back for a hand catch landing. With some time left I decided to try flying from a school yard that was at a lower elevation to see how the lift was there.

UMX Radian Gliding High

Looking Down the Hill

Dense Trees and Construction on Behind Me

At the schoolyard I found some good lift also but wasn’t able to get the glider to climb from such a low altitude.  I had flown the old javelin launch RC gliders from this site before but really not room for much larger gliders.  One flight I hit lift up fairly high but when the glider is already high letting it climb much higher it is soon a tiny speck.  To me the thrill with the UMX Radian is finding as many thermals as possible and climbing for a relatively short time before finding another.

Flying Out of Schoolyard

There was a young boy at the playground carrying around a non-flying model of what looked like a B-17. His mother was not far away working in a garden plot so I thought it was alright to talk to him when he came over.  It is not very often that I find young kids – guessing maybe 8 years old that are interested in airplanes. He said he had a model drone that was broken; I wish I would have had a free flight foam glider to have given him.  I patiently answered all the questions he had many were about all the switches on my transmitter and what are they used for.

Fun afternoon but it was time for supper.

Bill Kuhl

Related Articles

UMX Radian Initial Impressions

Slope Soaring UMX Radian and Mobbing of an Eagle

Small Gliders - Small Slopes

30 Second Film Festival - Winona

Recently I was part of a local film festival featuring videos that were only 30 seconds long. This is something new to our area as far as I know but there are events around the world that feature videos of varying short lengths. Festival director Crystal Hegge had attended an event with 10 second videos which really seems short to me. Unfortunately I did not get a chance to create a video this year but I was part of the Kids Entertainment before the video viewing.  Videos were shown on a large video screen in the band shell which provided for a good number of bench seats although most appeared to be filled. In the large grassy area behind the band shell I demonstrated model airplanes and water rockets.

Hammer Down Catapult Gliders

To start out my demonstration I flew a Radian Pro electric glider which has a 2-meter wingspan, this was the largest model I flew but it was easy visible thought out the park. Some adults had questions about the glider but I switched to the water rocket launching so the kids could be part of the activity. I also gave out some of my foam Hammer Down Catapult gliders to interested people. I finished off by flying some smaller radio control airplanes including the Guillow’s DHC-2 Beaver that was built for electric radio control.

Radian Pro Electric RC Glider

Volunteer to Pump Up Rockets

Blast Off Leaves Water Vapor

With my toys put away I headed over to view the 30 second videos. I was impressed by the number of entries by young people and the quality of what they had done. It seems like in more technical endeavors; Winona is really lacking for outlets for young people to develop their skills. The help that Jade Fang had given many people in creating videos to showcase their unique talents was also a standout to me. Having FREE events in some of Winona’s public area such as this event and Live @ The Levee should be a good start in building community spirit.

Good Crowd for Videos

Videos are Starting

Bill Kuhl

Related Links and Videos

Frozen River Film Festival 30 Second Film Update

Every Frame Counts Frozen River to Debut - Winona Daily News

Commercial-length art: FRFF's '30 Seconds in Winona' mini-film fest set for Saturday - Winona Daily News

Visit Winona Videos by Cynthya Porter

Visit Winona I
Visit Winona II

Video Production Jade Fang

Jade Fang 
Live @ The Levee
Joe Kafer
Redhorse Gallery
Jamie Harper
Julie Johnston
Mary Lee Eichen

Monday, August 25, 2014

Fortunatas Coffee Roasting/Shop

I had the opportunity this weekend to experience a fairly new coffee shop in the Winona area that is part of what makes living in a river town such a fun experience. The proprietor of the coffee house Joe Libra I have known for several years and had purchased a beautiful wood kayak from him when he was building kayaks. Joe is a man of many talents and he has done a wonderful job creating a look to the building that is really unique including the front end Volkswagon bus from the early 60’s that extends out on the deck. Looking up to the ceiling you can find just about anything including Santa Claus on a surfboard or a large model airplane on pontoons.

If you can’t make the trip to Fountain City Wisconsin a town of almost 1000 a few miles from Winona you could order Joe’s coffee products online through this link   The beans are fair trade and organic beans from around the world.  The coffee roasting/shop was named after Joe’s maternal grandmother, Fortunata Pintaudi, a 100% Italian woman.

Kayak Built by Joe Libra

Sunday mornings there is often live music, Noah Hittner performed this Sunday on acoustic guitar with amplification.  I enjoyed the music very much and it wasn’t too loud that we couldn’t continue to chat. Noah is very talented writing music and books, be sure to check out his website to learn more.

On the big deck I found people I knew and others that I would soon get to know. There was a retired farmer that is a regular there that told me he came because there were a lot of smart people that come to the coffee house.  I knew a family there that drove hybrid cars and we started talking about the latest in energy efficient vehicles and it wasn’t long and other people were joining to the conversation. 

Noah Hittner

View of River From the Deck

Normal business hours are 7:00 am to 2 p.m. – closed on Monday. If I didn’t work in Winona no doubt I would be at Fortunatas often.

Bill Kuhl

30 Second Video by Jade Fang

Tuesday, August 19, 2014

Allegro Lite Sailplane - Finished and Flying

At least ten years ago I heard of free plans for a 2-meter radio control sailplane that was about the ultimate in performance for a glider of this size at the time. Dr. Mark Drela famous for so many innovations in model aviation and Professor of Fluid Dynamics in the Department of Aeronautics and Astronautics at MIT designed this glider. It is interesting to note that the human powered airplane Daedalus that his team built set the human-powered flight record of 72.44 miles in just under 4 hours in 1988 has the same rather unconventional rudder and stabilizer layout as the Allegro Lite glider. Dr. Drela also set a record for the fastest human powered water vehicle, has shared record breaking free flight indoor glider model design, and developed subsonic airfoil program known as XFOIL.

Finished Allegro Lite RC Sailplane

Allegro in Flight

With the all the plans and instructions downloaded from the Charles Rivers website I started the construction of the Allegro Lite on a glass surface using bags of bird shot for weight as recommended. Building the wing was an overwhelming task for me, it is a combination of balsa and composite materials. Spar construction consists of end grain balsa sandwiched between carbon fiber strips. This is wrapped with Kevlar tow (loose fibers) and then painted with a slow curing epoxy. The design objective for this sailplane was for it to be able to withstand any flying load including full-pedal winch launches. A friend of mine did manage to break the tailboom on a particularly brutal launch with his Allegro Lite.

Wing Spar and Tip

Another View of Spar After Sheeting 

Obtaining the special components needed for this project was somewhat easier in that I obtained a partial kit that had those composite components and laser-cut ribs. Building the wing was such a task that at some point I felt like if I finished this plane and it crashed it I would be devastated. It sat for years at about 90% complete and then I started slowly working on it again last winter. Just within the last couple of weeks have I started flying the glider. It flies very well but somewhat faster than I had anticipated. Still nervous flying my pride and joy I have only made thermal flights of no more than 5 minutes by making big circles over the field. 

Hatch Held With Magnets

If more nose weight could be crammed in the tiny nose pod it would be good to try because the CG is slightly behind the recommended spot and it seems to be close to tip-stalling occasionally. I used powerful tiny magnets to hold on the nose hatch this has worked very well.

What a feeling of accomplishment I have from building this model airplane.

Bill Kuhl

Additional Resources

Charles River RC Article and Plans for Allegro Lite

Dr. Mark Drela MIT

XFOIL Airfoil Program

Daedalus Human-powered Record Setting Airplane

Download Plans for Rubber Power Free Flight Corsair Designed by Mark Drela

Human Powered Speed Record Set on Water - Decavitator

Wednesday, August 13, 2014

Trying to Add More Zip to Zip Wing Model Airplane

Original Zip Wing Airplane
For me some of the most fun I have with the model aviation hobby is trying to improve the performance of a model airplane. Often just minor tweaks are needed but other times a more radical approach is needed. In the blog post Zip Wing Electric Free Flight Plane I described trying to fly this electric free flight airplane available where toys are sold. Dry cell batteries power the electric motor and it has an electronic timer that shuts off the motor after a few seconds. Out the box the airplane lacks stability because the wing is so flat lacking dihedral. By bending the wings up I was able to improve the stability some but the flights never got very high and it came down fast.

Zip Wing Plane With Tissue Covered Wing

Large Wing and Tailboom Added

First attempt at improving the performance was just to add additional wing area to the wing by taping on foam material to the trailing edge of the wing.  If this worked it would be an easy fix anyone could do but it appeared to just make the airplane fly slower. From a previous flight one of the propeller blades had come off when it hit a curb, my epoxy fix did not hold.

Normally I do not give up easily and I remembered having a much larger tissue-covered balsa wing that worked well on some simple radio control airplanes. The wing was on a plane that my friend Floyd Richards had built for the Twin Turbo thrust vectoring radio we used on our early indoor RC airplanes. The plane flew well outdoors too when it was calm and I installed the RC to this plane from an Air Hog Aero Ace airplane. It flew amazingly well yet it was much heavier and larger than the Air Hog plane it came from.

Wing on RC Plane Flew Easily With the Power in Small Plane

My next thought was to put this wing on the Zip Wing plane hoping it would climb higher and glide longer. With the big wing attached the airplane looked really short so I extended the tailboom with a carbon rod, found a 3-bladed propeller to replace the broken one.

Foam Added to Wing from Plates

Test flights show the highly modified airplane flies different, much slower and the flight was more stable. With the electric motor that only runs maybe 10 seconds, it still doesn’t get very high. Competition free flight electric airplanes like the E36 have a high power to weight ratio and the airplane climbs very high in those few seconds.  My modified airplane lumbers along in a gradual climb which only gets it maybe 40 feet high.  

Lumbering Along

Still I do not feel like I wasted my time, it was fun and I have a great airplane to fly in a ball field.

Bill Kuhl

Related Blog Posts 

Tuesday, August 12, 2014

Small Gliders - Small Slopes

UMX ASK21 and UMX Radian

With the ever shrinking possibilities for electronics it has made it possible to purchase radio control airplanes off the shelf at local hobby shops that were not available a few years ago. Many of these planes power the radio control equipment and possibly the electric motor powering the airplane from a single lithium polymer cell battery 3.7 volts 160 mah. Based on the standard of this battery I have several airplanes and several batteries that I can swap between any of the airplanes. These batteries typically sell for under $10 and you can purchase a charger that will charge two or more batteries at a time. With several batteries charged a good amount of flying can be done without having to recharge a battery.


UMX Radian

4 160 Mah Batteries and Charger

My primary interest in radio control flying is sailplanes and I have two model sailplanes that I purchased off the shelf at local hobby shop Everything Hobby; UMX ASK 21 and UMX Radian that come complete with everything but the transmitter.  I had given a short review of these gliders in previous blog posts; in this post I wanted to convey the fun of flying the small gliders off smaller slopes, this is slope soaring. In slope soaring the wind is deflected up the face of a hill giving vertical component that can lift the glider faster than it is coming down the glide slope. 

It is possible to fly a larger glider from a small slope and probably more efficient; what I find is these small gliders look more in scale with the hill size and take more abuse because of less kinetic energy. With less available lift much of the time on the small slope it requires constant attention to flying as smooth as possible and finding the spots on the hill that provide the greatest lift. There will be times when the glider is flying within a couple feet of the hill and other times when the glider might be 75 feet above the hill. This is very interactive model flying that requires constant attention by the pilot; I find it fun because it is challenging.

Typical Small Slope

Last weekend I flew both the UMX ASK21 and the UMX Radian from the same hill. It appeared to me that the Radian could float on less lift but the ASK21 was more maneuverable with the addition of aileron control. The scale looks of the ASK21 are just so cool to see cruising by on the slope but the ability to use the electric motor on the Radian can often save you from having to walk on a steep hill to retrieve a glider on the ground. Some people have put ballast on these gliders but I have not flown in wind greater than 15 mph unballasted.

Guillow's DHC2 Beaver Uses 160 Mah Battery


I slope soared the UMX Radian off the levee wall fairly successfully but did hit the railing one time breaking the tail. It should have been a minor repair but the "foam safe CA" I used started to eat away the foam. I noticed on the bottle it says for most foams. 

This Wall Was the Slope

Sloping the Wall

This CA Attacked the Foam

One flight was really pretty good lasting several minutes, it is challenging for sure staying in small lift zone and not hitting anything solid.

Bill Kuhl

Be Sure to Check Out My:  Small Slope RC Soaring Webpage

Related Blog Posts

UMX ASK21 Sailplane
Slope Soaring UMX Radian and Mobbing

DHC-2 Beaver RC Conversion

Guillows DHC2 Beaver Flies