I check the stunt forums every day, read each issue of Stunt News, virtually cover to cover, and keep an eye out for other possible sources of usable information. last fall I noticed a number of comments to the effect that disabling Rabe Rudders seemed to help the performance of some stunt ships, particularly those using reverse rotating motors.
It seemed time to try again to make gyroscopic precessional effects and the use of a Rabe rudder more understandable. I started another article to clarify, not only gyroscopic effects on our airplanes but to illustrate how a simple rudder linkage might minimize the sometimes negative effects of gyros on our maneuvers.
Our stunt ships are pulled through the air by propellers. These propellers exhibit the physical characteristics of gyroscopes and are subject to precession when the prop disk is pitched or yawed. Gyroscopic precession is poorly understood by many modelers and the existence of these effects seems doubted by others. An example of gyroscopic precessional forces can be experienced by picking up your airplane with the engine running. Point the nose rapidly up and down. Left and right yaws should be apparent as the airplane's pitch attitude is changed. This is a hazardous experiment. If you must, at least use extreme care. This experiment can also be performed using a fairly large prop on a strong hand drill.
Typically, we experience gyroscopic precession each time we make a high rate, nose down pitch in our outside maneuvers and lose a bit of line tension as our airplanes yaw slightly inward. Gyroscopic yaw is also present in our inside squares creating a bit more tension with outward yaw, but it's typically unnoticed. In short, elevators pitch our stunt ships and create gyroscopic yaw. If the elevators are connected to the rudder by a simple pushrod, gyroscopic yaw can then be balanced by deflecting the rudder whenever the elevators move.
This works well enough unless the engine/motor and prop rotation are reversed. With reverse rotation, a typical Rabe rudder linkage would magnify gyroscopic effects instead of minimizing them. This erroneous linkage could make these stunt ships with reverse rotation virtually unflyable.
Over the years, I have written a number of articles on gyroscopic precession in our stunt ships, and a practical way of minimizing related negative effects to outside maneuvers. This latest Rabe Rudder and Reverse Rotation article is my current effort to be enlightening, and, hopefully interesting. It contains a total of about 4300 words and 50 photos. It's too big to fit comfortably into either Stunthangar or Stuka Stunt forums. I was also sure that it wouldn't be much fun trying to "shoehorn" it down a manageable size for either forum. Also, I didn't want to offer it to Stunt News. I'm not comfortable there since Tom Morris left. The easy decision would be to tack it onto the contents of the "Al's Models 3" disk.
The five years old "Al's Models 3" disk, already contains 153,485 words, 1300 pages of text and photos and a half hour of video. It's a combination of two previously sold Al's Models disks. The first disk sold was "Al's Models" which, in this collection, is now "Book 1". The second disk sold was "Al's Models 2" which, in this collection, is now "Book 2".
Material already on "Al's Models 3" includes a 53,662 word Snaggletooth Mustang building tutorial and a 25,047 word autobiography published in Control line World magazine eight years ago.
"Book 2" led off with the 1973 Sea Fury article "Go For Broke", the 1978 Mustang article "Evolution of a Thoroughbred" and a large Mustunt IV tutorial. Most would consider these to be significant classics justifying new exposure to our current crop of stunt flyers. The rest of Book 2 is mostly a collection of my files of Stuka Stunt postings, some dating back more than twenty years. In fact, most of the material on these disks is copied from a number of publications. Whatever the sources, copied or original to these disks, it is all written and photographed by me. Book 2 also contains a photo gallery and a half hour of video.
The "Book 3" addition to the "Al's Models 4" disk began with the Rabe Rudder article, a building tutorial on the construction of the Classic legal Mustunt II and an article containing descriptions, photos and plans of all of my airplanes. Once again, I also searched my files to find useful, and hopefully interesting information accumulated in the eight years since "Al's Models 3".
The new total for "Al's Models 4" is 187,426 words and 1601 pages of text and photos. I gathered the contents of these three books as a resource, an unmatched collection of information containing a half century of control line stunt design, building and flying while employed in an airline career.
Somewhere, during the writing and compiling of Book 3, I created a flaw in the text with a broken or corrupted entry. I completed Book 3 but it wouldn't copy. It appeared in the first few "Al's Models 4" disk contents as:
~$'s Models Disk 3.
Attempts to copy Book 3 kept meeting with Microsoft comments about Book 3 causing serious error, and Microsoft would recover the document if I didn't mind losing my formatting and 300 pictures. My computer skills were inadequate to fix the problem so I added a new Book 3 copy, in addition to the corrupted Book 3, to the contents which would play, if a bit slow to load.
Al's Models Book 3
While looking for help with the problem and seeking comment, I sent out 20 copies of the new "Al's Models 4" with both Book 3 entries in the contents. The computer problem was solved with help from friends and appears no more. To improve downloading, book 3 joined books 1 and 2 in PDF format. Now, all three books download instantly. If anyone has one of those first 20 disks which included both copies of Book 3 which fail to load properly, contact me for a replacement.
With problems solved, Al's Models 4 is available for purchase. See Classifieds for address and price.
Al
Topic: Gyroscopic precession and Al's Models 4 DVD (Read 9284 times)
