Well, it's spring and Sun-n-Fun is almost here. I'm planning to go again but since it is the week after Easter, I'll get there a little later, hopefully at our usual spot on the south side of the pond. All the Sun-n-Fun details can be found at Sun-n-Fun.org.

Alvin brought John Sheridan, the builder of the overweight Rag Wing Special ultralite to our last meeting. I've gone back into my directory issues of Kitplanes to find the airplane. They show the empty weight at 278# either with a Kawasaki or the later 2Si engine. The phrase "ultralite replica of the 40's" is used in the description. Obviously misleading, not an ultralite. But John is about 60# heavier.

Three possibilities are: 1) John added things to the airplane that weren't on the original, 2) he intentionally or unintentionally built it heavier, or 3) the original airplane built according to the plans weighed more than 278#. I believe all three are true. The first is obvious, the second is a little harder. Wood is the most difficult building material to use to duplicate a specific weight. And, of course, the designers never tell you what each part should weigh so you don't know whether your wing or other part is too heavy until your done, by which time you can't do anything. Wood density (and strength) vary by 10% or more between trees and boards. Add to that the effects of grain and the question of which way should the grain run in different pieces and we naturally tend to make the pieces just a little bigger. This "compensation" adds up fast with the smallest pieces having the largest gain. For instance, if you are cutting 1/4 in sq rib stock and cut 1/32 in oversize, the weight will be increased by 26%. Douglas Fir is significantly heavier than Sitka Spruce as is birch rather than mahogany plywood. Larger gussets and excess glue not scraped off are significant. Varnish is non-structural and heavy. It does NOT prevent moisture absorption; it only slows it down. Old Forest Products Laboratory data on moisture transmission through coatings showed that while there were differences between resins, the major effect came when non-moisture transmitting pigments such as aluminum powder were added which effectively reduced the resin volume in the coating which could transport water through it . So we would be better off painting our propellers with aluminum paint; and that was often done before WWII. Covering can get heavy really fast since the areas are large. Weight and convenience are why most ultralites were covered with sailcloth. If using dope, I would go with a light thinned first coat and put aluminum in the next. Quit there if you can store it inside, otherwise add another coat of aluminum.

All designers tend to exaggerate the numbers a bit so the 278# may be unrealistic. When this aircraft was designed, many people felt that the ultralite weight limit would be raised. However, most ultralites were powered by the Rotax 277. John said that his Kawasaki engine weighed 78#. The Rotax 277 weighs a bit less than 50# so substitution onto a 278# airplane would make a legal ultralite. But that is not an option as John's airplane is way too heavy.

Speaking of ultralites, in January, Tim Perkins told us of his efforts to put an airstrip on his farm. Thinking about it, since ultralites aren't aircraft, they don't need airports, so he should be legally able to fly an ultralite off his farm; just as his neighbors can run around in their ATV's, which aren't cars.

Other stuff:    www.learn-to-fly.biz    good general information on aviation.

                      www.lmaeronautics.com     manuals on F-16 aircraft now on line

                      www.usafa.af.mil/wing/34og/94fts.index.html  for information on the soaring program that Steve is in.