Friday, May 30, 2014

500 Years of Aviation Presentation - Friendship Center

Any chance I can get to talk about aviation and show off flying models I take. Yesterday I gave a 45 minute presentation at the Winona Friendship Center that was an updated version a presentation I had done previously. This time I demonstrated flying small quadcopters and walkalong gliders. For non-flying visual aids I had wood models of Leonardo Da Vinci Aerial Screw and Ornithopter and demonstrated the difference between a electric motor with brushes and a brushless motor. Sort of flying demonstration was the flying ball in an air stream.

The major theme I try to get across in the presentations is how ideas inspire others to expand on and improve concepts. Besides talking about the historic aviators I show the idea of  how the FPG-9 (foam plate glider) can be expanded on. I launch my foam gliders in front of the audience and explain what ideas I incorporated in each design.

Tiny Quadcopter Great for Flying in Small Areas

Rather Small Area to Fly but I Did

To show technology of model aviation has become so sophisticated I show my modern computer radio with audio prompts, downloadable software updates, and model memory for a couple hundred models. I flew the MiniVapor which flies well in small areas. I also flew a free flight mini-stick to show how a free flight airplane can fly in a tiny area also.

Mini Vapor

Hammer Down Foam Glider

Foam Plate and Straw Glider

Foam Jet II Glider

Granted not that many people attended but I have done presentations like this several times so that is understandable. It really inspired some good conversation afterwards for at least 30 minutes, I thought that was the best part. One person saw the possibilities for some kid events based on some of what they had seen.

Bill Kuhl

Related Links

Foam Plate and Straw Gliders
Rubber Powered Foam Airplanes
Hammer Down Foam Catapult Glider
Foam Jet II Glider

Rubber Powered Orntithopter
Progression of Ideas Foam Gliders

Wednesday, May 21, 2014

Free Flight Discus Glider Update

Short update on my progress with the free flight discus launched glider Maxima 30, I am indeed making progress.  The first several flying sessions it would consist of making several flights and then having to repair the glider afterwards.  Last weekend I was able to fly from a somewhat larger field but as the breeze came up I found out the field wasn’t large enough for my DT duration and the glider ended up in the top of a tree at the edge of a field.  Someone that was at the field knew a guy that did tree trimming and I had called him to get it down, luckily it dislodged from the branch and came down saving me some money.

Yesterday was the first day that I can remember this year that the wind was light for the entire day so I left work an hour early to do some flying. This model airplane sure has been a lesson in how making tiny changes can make a big difference. The grass is getting really long again at this field so there would have been some cushion if the glider crashed after launch or because of bad trim but it never did. I fact the landings were always very gentle. 

The trim of the glider seems to change between flying sessions, I am not sure if that is common or if I do not have it dialed in yet, maybe a combination of both. Transition at the top of the launch is getting better but the glider seems to go through some small oscillations and then the glide is good.  More nose weight was added in later flights and the glide improved.  

The DT worked very well yesterday and I see it is possible in low wind conditions to have a glider flying high yet still get it down within the small field most of the time. Now my focus is going to be improving the flight path for better duration.

Unwinding With Free Flight Discus Glider  - about my struggles at the start Bill Kuhl

Short video of stalling glide and DT

Tuesday, May 20, 2014

First RC Glider Contest 2014

Last weekend was the first thermal soaring glider contest this year in Rochester Minnesota. Last month it was too windy so we were slope soaring and it was almost too windy for that. Conditions for the contest were gusty with the wind really low and then gusts of 20 mph. Some strong thermal lift was to be found at times. Before the contest started I was flying my free flight discus launch glider and managed to get it stuck in a tree at the edge of the field, it did blow down which I was very happy about.

Wayne Norrie Arranges Monthly Events

Format of the contest was a ladder of flights starting at 3 minutes and going up at 2 minute intervals. Some people were flying Radian electric gliders and some were using hi-start or electric winch. I brought my Shadow 2 meter glider out after repairing from the last crash. I did a faulty repair job, when the plane was launched someone noticed the canopy fell off on launch. I continued to fly but noticed the wing was not straight when the glider landed, the section of fuselage holding the wing that ripped out on the last crash was coming lose again. 

Supra Landing

Turns out there was another guy at the contest flying a Shadow 2-meter but his wing was built from balsa and covered with plastic covering. This plane only used rudder and elevator control while mine is fullhouse. The owner of the Shadow gave me some good suggestions of how to repair my glider with additional fiberglass which I have since done. The real large glider flying was a Supra which flew amazingly well with the longest flight of the contest at over 18 minutes. Dean, the owner of the Supra suggested to me that I put some ballast in my Gentle Lady glider to fly in the wind. This really did help and I was able to ride some thermals to get in my 3 and 5 minute flights but longer flights were elusive for me. At one point the Gentle Lady might have continued to speck height but it was getting far downwind and I did not want to risk not getting back.  I was told that gliders like the Supra can change wing settings and go 100 mph upwind if needed.

Other Shadow with Balsa Wing

It sure was good to get out and do some thermal soaring with other pilots and the large birds that were flying over the field also.  

My Gliders for the Contest

Free Flight DLG Stuck in Tree

Bill Kuhl

Additional Related Posts

Onewinch   Pully Winch system seen in first picture

Monday, May 12, 2014

Unwinding With a Free Flight Discus Launch Glider

For me the model aviation hobby stays interesting if I take on new types of projects which present new challenges.  This past winter I built a discus launch free flight glider known as the Maxima 30 designed by Len Surtees. I have flown radio controlled DLG gliders before but I found out that it is more of a challenge when you have no control of the glider when it leaves your fingers.  Launching a glider by spinning around while holding one wing tip can give tremendous launch height, but can also result in plane-breaking crashes as the glider hits the ground at high speed. 

Construction of the wing uses solid sections of balsa that require shaping but there are large sections of the wing which use balsa ribs. Carbon fiber strips run the length of the wing both top and bottom and the dihedral breaks are reinforced with fiberglass. Covering was with a material known as Polyspan which worked well and appears to be very tough.

As of yet I had not installed a dethermalizer (DT) in a model plane which presented a new challenge that I have much to learn about. The Smoothie MK III was included with the kit but I have had trouble gluing the arm to the rotary damper part of the timer. I ended up building by own arm out of tubing. In testing using a rubber band pulling on the rotary timer I could not get it to run for more than 30 seconds. If less tension was used it would stop. Switching to tiny springs I had purchased for this purpose worked much better and would give a much longer time before the DT would pop up.

DT Set

DT Popped Up

Learning to launch the Maxima has been more difficult than I expected, even after watching a DVD I purchased from the National Free Flight Society about DLG and Catapult gliders. The crashes normally are because you let go of the glider wrong and it curves the opposite direction it should and crashes shortly after launch or it stalls and does not recover before hitting the ground. Luckily the ground has been fairly soft lately because of all the rain. Still I have broken the glider the glider several times either at the balsa and carbon boom pivot point joint or in the nose where it is cut out for the DT. One time the DT broke free from the nose and was lost in the grass, will have to install a new one.

DT Broke Free and Lost

The last time flying I did not have to make any repairs hopefully my launch technique is improving. Transition at the top of the launch could be better; either it goes downward too fast or into a series of stalls.  There is an adjustment screw under them boom that can be tweaked to adjust the glide. Any type of model free flight glider is more difficult to launch and adjust than one would think because it flies in two entirely different speed modes, high speed for launch and then a slow glide. 

Dive Too Steep

Soaring High

Hopefully I will have a future updated report on this where I can brag of many long flights without crashing.

5/12/2014 Update

Many times tips from someone that has had success can make all the difference. I found this thread on Hip Pocket website that was very helpful "TLG Beginner's Launch Guidance". The one thing I notice was the glider should be launched with very little angle upwards and the glider climbs upwards naturally. I was launching at a rather steep angle. With this knowledge I tried flying again but the recovery at the top of the launch was still poor.

Another idea I had was to give the glider more right turn to help it recover. I increased the  rudder shim with some masking tape wadded up.  This really helped and with a little adjustment of the pitch trim the glide recovery was much better. Too good in fact for the small field in the breeze, it drifted diagonally across the entire field and landed in the road. 

This time I called it enough before I lost the glider. That evening I installed another balsa rudder shim and replaced the DT.  Think I am making some real progress now.

5/12/2014 Update

New post on my progress.

Bill Kuhl

Thursday, May 8, 2014

2 Years 20,000 Miles on Prius Report

The 2011 Toyota Prius I purchased new in 2012 now is just over two years old and has very close to 20,000 miles on it. So far I still think it was a very good decision to purchase a hybrid car. As of yet there have been no problems with this car and the expected fuel mileage has been good. Average for summer driving is slightly above 50 mpg and during winter it dips into low 40 mpg range. It has handled fine for me when driving on slippery roads.

There still seems to be much confusion by most people on how a hybrid car functions. First of all unless you have a plugin hybrid, you do not charge the car from an external electrical source. The batteries are charged by the kinetic energy of the car when coasting or braking or by the gasoline engine. It is rather complicated how this all works but so far it has worked perfectly for me. Some of the time the engine is completely off such as when coasting or while the car is stopped.

This Might be Typical at 70 mph Highway

For the Toyota hybrid system the car can be powered entirely by the electric motor at lower speeds, powered entirely by the internal combustion engine, or a combination of electric and gas, this is controlled by the computer system in the car. Other hybrid systems may work slightly different. Your driving style and route can have much to do with the gas mileage results. The car begins moving first by electric to overcome the inertia, remember Newton's First Law of Motion?

Under Some Conditions Mileage is Really High

The internal engine in the Prius is an efficient design which helps greatly with the gas mileage. There are no belts on the engine for water pump, power steering, etc. The intake cycle of the engine is longer making for an engine than is more thermally efficient, that is more energy is converted from heat to useful mechanical energy. The claim is that this engine is 38% thermally efficient compared to around 20% average for typical gas engine. Without an electric assist for this type of engine the performance would be slow which is why it works well with the hybrid concept.

Other aspects of the car that contribute to efficiency are the transmission which constantly varies for the load. Tires that are designed for higher-mileage with pressure monitoring valve stems.  The design of the body is more aerodynamic than most cars also.

I look forward to when full electrical cars are practical for most people.
Bill Kuhl

Monday, May 5, 2014

Zip Wing Electric Free Flight Plane Available Where Toys are Sold

Passing through the toy isle at a department store I decided to see if there any actual flying model airplanes any longer. Not much of a selection but they did have the Air Hogs Zip Wing electric free flight model. I remember people discussing this on a free flight forum.  The performance is not wonderful but it is about perfect for a school yard or park. Like most toy store model airplanes it is not real stable out of the box.  The electric motor is powered by two AAA dry cell batteries which doesn’t give a rocket-like climb but it is adequate.

What I like about this plane is that it makes it so easy to get repeated flights without having to charge, pump, or wind up the plane before flying again.  The airplane has a built-in timer that cuts the power after about 10 seconds, the propeller folds back for the glide.  Not a real good glide however but for school yard flying that is probably a good thing.

Wing Needs More Dihedral

Like any free flight airplane, some adjustments might be needed to get the airplane to fly correctly. On the first launch of my Zip wing it nosed to the ground, it needed some up trim from the elevator surface. The airplane does not have enough dihedral, the instructional video on the Air Hogs website shows how to bend the wing to create some dihedral which is what I tried to do. I want to try find a better solution, the plane tends to fly one direction and then another.

I ran across a video someone posted on Youtube where they could not get the plane to fly, it always turned to the left and crashed.  This is the challenge and the fun of free flight airplanes, you MUST learn how to do the adjustments to correct the problem. Do not keep launching the airplane when the flight path is wrong. When I got my plane adjusted I was able to give it a fairly hard throw and it gained more altitude. What I did do wrong was not use a decal to hold the vertical fin in place and I lost it; a new fin was created from some foam I had.

Watch for more ideas on how to improve this plane as I try more modifications.

5/16/2014 Update

I added extra dihedral by bending the wing tips up and taping with clear tape. This might be more dihedral than needed for stability but I thought if the tape was removed maybe some of the bend would remain. The airplane did seem more stable in flight but I think maybe the wing was not lifting as well. My next idea is to add foam material to the trailing edge of the wing to increase wing area.

Bill Kuhl

Video of Airplane That Needs Adjustment