Tuesday, June 20, 2017

Mountain Lion Mark II – Laser-cut Planes

Teaching a summer projects building class at local university (College for Kids) for many years I have tried a wide variety of science related projects; originally it was all model airplanes. In the later years it has been a wide variety of projects such as model solar cars, water rockets, simple electric motor, mousetrap cars, syringe hydraulic arm, and model airplanes.  Often the projects were construction article on my Ideas-Inspire.com website and this was a way to test out how the projects worked out when students constructed them. The down side to using what was on my website was I created my own kits which took so much time, it did save money however. If a shop environment were available with more tools, students could do more of the work.

Mountain Lion Mk II

For this years’ class I decided I was going to purchase most of the kits using some of the money made from advertising on my website. What I learn should be helpful for teachers that would not have the time to create kits for even larger groups of students. The vendors I used were smaller companies that I like to support. 

This year I wanted to add a balsa and tissue covered airplane to the list of projects and was looking for a design where no sharp blades were needed. Doing an online search I came across Laser-cut Planes and the Mountain Lion Mark II which fit the requirements and was a reasonable price when purchased in bulk. A rather unique feature in the construction was that most pieces were temporarily held together with stickers, building boards or pins were not needed.

Other than glue, everything is included to build the airplanes including tissue for covering and rubber strip for motors.  For my sample plane I used Sigment model cement and CA for final assembly, tissue was adhered with glue stick.  Included are pattern sheets to assemble wing and stabilizer over but one set of complete instructions for the teacher.

I pressed the parts out of the laser cut sheets without using a knife at all, and I did no sanding. When placing the stickers over the joints I used one hand to push the joints together as tight as possible and put the sticker on with the other hand.  Out on the tips of the wing and stabilizer because of the direction of the grain it is rather fragile.

Note: 6-21-2017

For each wingtip there is a balsa doubler included to reinforce the weak spot because of the grain direction.

Bill Kuhl

Related Links

http://www.lasercutplanes.com/  - Mountain Lion Mk II and other kits

http://www.docfizzix.com - using mousetrap car kits from Doc Fizzix

http://www.everythinghobby.com - purchased rubber powered helicopters from local hobby shop

Thursday, June 15, 2017

E36 Free Flight 2017 Progress – Sometimes I go Backwards

If it was too easy it wouldn’t be so darn fun; at least that is how I feel about my faster climbing free flight models.  Adjusting somewhat slower climbing models like my e20 Sky Demon and the electric Sniffer provided me with some challenges but both are adjusted pretty well now but I am still adjusting the power pattern on the e36 Starduster. 

BMJR e36 Starduster

Last weekend I thought the climb looked really good and it was consistent, my attempt at setting 5 second DT did not do as well and the plane hit the ground hard enough to break the fuselage in half. It was a quick repair and it was still climbing in a consistent power pattern. I had originally put a lot of stab tilt in the stab mount thinking it was needed to get left glide. It turns out there was too much left glide so I kept putting shims under the low side. What I had not thought of was this was shimming the front of the stabilizer on both sides creating more positive incidence which gave the plane less climb which is what was needed.

E36 Starduster

With all the shims to get the stab level, the stab platform was only supporting the bottom of the stab in a couple of small spots.  So in my fix up for the next flying session I cut off all the shims and re-glued the stab platform level; it looked much better. I also made a magnetic hatch for the battery compartment.

Stab Tilt Diagram

Shimming to Make Level Again Created Positive Incidence

Stab Level Took Out Positive Incidence

I am slowly learning with any change, start with very short motor run and quick DT.  That is what I did and a good thing, the airplane was doing half a loop after launch and the turn was more to the right.  I tried launching more to the left but it was obvious it was going up too much. I had other things to do but I went flying again later and started shimming the front of the stab, the power pattern was getting better. Finally it dawned on me what was happening and I continued to add more shims. The flights were now very consistent. 

Magnetic Battery Cover

When I got home I put in a permanent shim and also a small shim for the motor. The glide has plenty of left; it is only in power phase that it wants to go right. Next time I will proceed very carefully with the new changes.  The more flying I do with these free flight models the more comfortable I am making trim adjustments and interpreting the  results.  

Bill Kuhl

http://www.bmjrmodels.com/free-flight/e-36/Starduster-E-36  BMJR Models Starduster e36

http://www.texastimers.com/  Texas Timers  eMAX timer and accessories

Thursday, June 8, 2017

Fishing Success and the Opportunity

My fishing success this year has really been a mix of good results and going home without catching a single fished; “skunked” is a common way of describing it.  Fishing for trout early in the season which is normally productive had me leaving without a single fish two times in a row, fishing at spots that I had caught fish before. It had me thinking about what had changed and what I could do to correct it.

I am doing mainly catch and release

Talking to other people I found that some people have had good success but also talking to land owner next to the water I had been fishing he told me lately he never sees anyone leaving with fish. From talking to people that know about the habitat that trout prefer I found out that some stream areas were filling in with sand which is bad for the eco system. When I tried fishing in stream areas that had a rocky bottom I started to catch fish again.

Brown Trout

When bass fishing season opened I tried casting a couple of times from shore of the small lake  a few blocks from my house just before sunset and again was skunked, same results from a pond that I normally catch bass in too.  Fishing there later into the evening at the pond I did have some luck. 

I find that success in many endeavors in life is dependent on finding the better opportunities. Google definition is “a set of circumstances that makes it possible to do something”.  A few days ago I was again fishing for largemouth bass in the evening at a lake close to my house with no luck at all. At the point when I was feeling a little frustrated I was about ready to go home but saw a young man fishing in the same general area and inquired about his fishing success. He told me it had been slow today but a few days ago he had caught a 5 pound bass in another area of the lake. I decided to try spots along the way to the area he had mentioned.

Big Bass

When I arrived at the mentioned spot I noticed a bunch of movement in the water just below the surface, I had never seen the fish this active before. Just down from this I noticed I noticed a blue heron in the water, no doubt doing some fishing also. I threw out my HooDoo lure just purchased from Hogline Baitshop and caught a fish on the first cast. Next cast and my drag is slipping like crazy, I knew I had a really large fish on. Besides the fish there was a bunch of weeds covering but I got it up on shore and pulled the weeds off. It was the biggest largemouth bass I had ever caught, my guess around 5 pounds. After taking a picture I released it and caught a few more slightly smaller fish until it was completely dark.

Blue Heron

Realizing I had possibly found a good opportunity from knowing the best time and place to fish I went back the next evening and caught another bass the same size and a few more.  I missed a day but when I tried same spot again I noticed very little ripples in the water and no blue heron fishing. The bass I caught were much smaller and less frequent. 

RC Sailplane Flying

In my model aviation hobby I watch the weather forecasts and look for predictions of cool morning temperatures that rise rapidly during the day which should be conducive to good thermal air current production for RC sailplanes or free flight models. If you are an investor in the stock market, finding the right opportunities is really important but often not easy.

When it comes to leisure activities finding the best opportunity isn’t everything, it is often just nice to just have the opportunity to do an activity you enjoy.

Bill Kuhl

Tuesday, June 6, 2017

Sniffer Electric Free Flight Report

In my hobby interests I try to use “adaptability” to enjoy what I have available to me in the local area. Locally we do not have an abundance of open area to fly free flight model airplanes. In the past I have flown small rubber powered models or gliders that if I lost it would not be too upsetting to me.  Somewhat larger free flight models to me can be more fun to build and challenging to get adjusted properly.

In my Build Report for the BMJR Sniffer I described the Sniffer kit that originally I was going to power with a Cox PeeWee .020 engine but decided to use a brushless electric motor and radio control for control of motor speed and dethermalizing (DT). I had thought it would be easy to connect the servo for rudder control but so far I am having more fun with an airplane that is almost free flight.

When I started flying the plane it flew right under power but changed to left for the glide but not always consistently so.  I added a rudder trim tab and forced the plane to fly to the left under power while maintaining a left glide. My concern was the plane might glide too much left but that does not appear to be a problem. The transition from power to glide is pretty smooth. When making trim adjustments it is so nice to be able to shut the motor down immediately or trip the DT to bring the plane down safely if it looks like a crash is likely.

Where I often fly there are many obstacles and if it looks like the glide will go over a building or tree I use the DT to bring it down before reaching the obstacle. This works pretty well except one time it came down into a chain link fence after the DT, no damage however.  If it is close to calm I will leave the power on until the Sniffer is pretty darn high. Most times it circles in the general area without drifting too much. When calm you can fly it around at reduced power and it will just circle around at like 30 feet high.

From my observation I think the propeller freewheeling in the glide has a rather detrimental effect on the glide, it also appears to cause the glide to be left. I say that as when I removed the propeller and did some test glides from a small hill the plane went straight. Spinning the propeller in the glide turns the motor which has a fair amount of friction. I know for better glide performance in P30 rubber power event people try to reduce that friction with their freewheel mechanisms.  I am going to look for a folding propeller for my motor.

This has been a fun project and gives me ideas for other sport models I could use RC DT on. Maybe a rubber powered model. 

Bill Kuhl