Tuesday, December 31, 2013

Path to Learning Physics

2013 has been an interesting year with my science guy activities but for 2014 I want to concentrate further on the educational aspects related to the projects on my website. I have been going through a process of trying to re-educate myself on much of what I might have learned in school in math or physics courses. Besides reading books there are so many educational tutorials on the Internet that are really helpful, a resource not available when I was in school.

An outline on how to approach learning physics and math which are so interrelated seemed to be a good first step for me.  To me it starts out with working to get the basic understanding and then work with the sample problems to be become more comfortable. I am finding some of the model aviation books that were rather technical in aerodynamics are now making more sense to me.

My Outline for Learning Physics includes becoming comfortable with the following:

  • The vocabulary
  • The symbols used in equations
  • Units of measure especially the metric system
  • Working easily with the trig functions
  • Working with and interpretation of graphs and working with data
  • Force diagrams

Feel free to comment or add to my outline items.

Happy New Year,

Bill Kuhl

Friday, December 27, 2013

Leonardo Da Vinci Ornithopter Kit

After building the Leonardo Da Vinci Pathfinder kit for the Aerial Screw I decided I just had to build the other flying kit, the ornithopter or flapping wing.  Leonardo was truly an amazing man but I do not think I will get a tattoo of a Leonardo sketch just because Miley Cyrus did.  Working over the Christmas holiday I had the kit assembled in a couple of days, the fit of the parts was good. My plan is to use both of these models in another aviation history presentation.

Completed Kit

Like the Aerial Screw it appears that no prototype was ever actually built by Leonardo, just the same the thought that was put into this is really amazing for the time period.  Model ornithopters are fairly common and I have built or bought a couple.

The Parts

Pilot Cable System Pulls Down Wings

Crank Mechanism Pulls Shaft Back and Forth 
Wings Levers Pull Down and Wings Go Up

The gears that were used in both kits made from wooden dowels and wood circles were of interest to me also, this type of gearing was typical for Leonardo's ideas. To find articles of this on the Internet I had to turn to my model airplane friends on the Internet to point me to the correct terminology. This type of gearing is known as "peg and cage"; the cage gear can also be known as a "lantern gear". The gearing part was just for model operation, if full-scale version the idea was the pilot would be pulling the wing halves down by a cable system as can be seen in the model.

Peg and Cage Gears

I find it interesting that it was not until 2006 that a man carrying flapping wing flying machine flew successfully. This was with the help of a model jet engine providing 60 pounds of thrust and the flight was only for 14 seconds.  Another flapping wing airplane without an engine was also tried but this was towed aloft.  Human powered propeller driven airplanes carrying humans have flown for many miles.

Bill Kuhl

Tuesday, December 17, 2013

Understanding Seconds Squared

In dealing with any physics problem of acceleration you will run across the notation of meters per second squared  m/s² often.  It has been established that the acceleration due to gravity is 9.8 m/s² whether a young Sir Isaac Newton was really hit on the head with an apple and came up with the theory of gravity is questionable.   The square of a number means multiplying it by itself 4² would be 4 x 4 = 16.  It is easy to visualize units of distance squared but the idea of time squared just did n’t make sense to me.  With a quick Internet search I found I was not alone, many people have been asking to have this clarified, and the following are parts of the most understandable explanations for me.

Distance Squared easy to visualize
Think of it Like This

One way of thinking of this is by wording it meter per second per second or as the velocity per second. This can be written out as   velocity  (meters per second) / time (per second).  If you look up the rules for division of fractions you multiply the divisor by the reciprocal.  In other words the numerator and divisor are flipped around the same can be done with the m/s² notation.

Bill Kuhl

Monday, December 16, 2013

Leonardo Da Vinci's Aerial Screw

Completed Kit Leonardo Da Vinci Aerial Screw
Always on the lookout for possible visual aids for aviation history presentations I came across a kit for an “Aerial Screw”, a design that Leonardo Da Vinci had drawn up but never built.  Leonardo was a man of many talents especially for such famous paintings as the Mona Lisa and the Last Supper. Born in 1452 his idea for a helicopter was way ahead of its time considering the first successful man carrying helicopters did not fly until the 1940’s.

Parts for the Kit

The kit is produced by the Pathfinders company in Canada along with many other wood kits. I was really impressed how well the parts were cut out from wood with a smooth finish and no sanding marks or laser burns.  For me the instructions were pretty good but dimensions are in centimeters so a ruler with metric scale is needed.  Working over the Thanksgiving holiday I had the kit assembled within three days using the white glue that is provided with the kit.

Turning a crank the upper screw part of the model turns.  Leonardo thought that four men could be turning cranks to produce enough thrust to lift a full-size Aerial Screw. We know now that would be possible.

Very short video of cranking the Aerial Screw:

Bill Kuhl

Tuesday, December 3, 2013

Computer Programming in My Past

I ran across a brochure from Watkins Agri the other day that had a graphic representing the output from a computer program I had written many years ago.  Watkins Products based in Winona Minnesota best known for consumer products such as their vanilla also had an agricultural division for many years.  When I worked there as a computer programmer/operator I wrote a program in Turbo Pascal language to create a graph representing milk production in relation to feed additives that Watkins sold.  This would seem to be a good application for a spreadsheet program like Excel but there must have been a reason for not going that route at that time. It was later converted to run through a spreadsheet.

Not Actual Output from Computer

Another project I had was converting the ration balancing program from running on a terminal to running on a smaller system.  The original plan was to convert to a small Unix system, in fact another person and myself went to Unix training.  For whatever reason that I cannot remember now I ended up converting it to run on a personal computer.  The program was written in COBOL and I transferred it to a pc-based COBOL language with no understanding of how the program really worked.  Amazingly it ran faster on a pc even back over 20 years ago.

Ration Balancing Program Ran on CRT

There was another picture of the computer room in the brochure which I worked in also as an operator, never really liked that part of the job.  In the picture there is a punch card reader that was used for doing a certain type of correction but was later phased out.  To the left were the big removable disk packs that were used for some storage and in the background you can see the big tape drives.   Computers sure have come a long ways.


Computer Room

Agri Lab Test

Bill Kuhl

Monday, December 2, 2013

Phantom Flash - Learning From My Mistake

Just completed a Phantom Flash rubber powered free flight from a kit sold by Volare Products with laser-cut parts. The kit is excellent but I think I lost the wing hold down rubber band and substituted a different rubber band. The Phantom Flash is a classic 1937 design by Joe Konefes and was a Comet Kit at one time, the plans can be easily found on the Internet for download. It was my introduction to indoor rubber power flying, my friend Floyd Richards gave me a copy of the plans and had me order really light balsa. The plane flew very well but I had trouble with ground looping for ROG take off.
Missing a Landing Gear Leg

Too Much Climb on this Flight

Landing Gear Intact

Shim in Front Rubber Band Wedged in Rear

Laser-cut Kit Includes Everything even LIGHT Tissue

It was fairly warm this past weekend for late November so I did test flight on my newly completed Phantom Flash. At times the wind was gusty and the ground was very hard but the chance to try out a new plane is always a thrill to me. First flight started fine but plane turned too much to the right and went into the ground rather hard. The plane appeared to be constructed straight so I was puzzled to why there was so much turn, the climb was rather erratic also. Sometimes too much up and other times not enough, on closer inspection I noticed the wing was angled too much one way. The rubber band I had used was not holding it down with enough force allowing the wing to shift which is why the plane would change trim. This was my fault in that I had lost the rubber band that came with the kit and substituted another one, I do not think this one had enough tension.

The plane also needed the wing ahead slightly farther for center of gravity balance but moving it ahead too far the motor stick was angled down which created less positive incidence. For a temporary fix I shimmed up the front wing support and I wedged part of the rubber band into the rear wing support.  Now I was getting good flights but the balsa landing gear had taken a heavy toll, I just kept flying. If I had the wing fastened securely from the start flights would have been better and the landing gear might have been fine. On the other hand maybe using all wire landing gear is a better idea but then that would destroy the nostalgic look.

Important Note: 
It has been suggested the balsa landing gear be reinforced by covering with tissue. Some people have used thin carbon strips for reinforcement also. Another suggestion is to make wire loop in the landing gear to absorb the shock.

Bill Kuhl
Embrace the Challenge