Free Flight: Duration
A quick recap of the two main types of carbon fiber used for wing construction: woven cloth and unidirectional strip. Woven carbon cloth is similar to fiberglass cloth but is, of course, black in color. Unfortunately, the available weights and weaves of carbon fiber cloth are much more limited. Perhaps the most useful for Free Flight purposes is 2.9-ounce plain-weave cloth. Lighter carbon cloths are available, but they can be very, very expensive. Like fiberglass cloth, carbon-fiber cloth is limp and pliable; it is always used in combination with epoxy resin and a form to produce a rigid molded shell, such as a D-box. The cloth can be cut easily with sharp scissors. Unidirectional strip is a rigid sheet or strip of carbon fiber. Carbon-fiber strip is available, like balsa, in various thicknesses, widths, and lengths. Thicknesses range from .001-.060 inch. The thinner strips (.001-.003) are used primarily for rib capstrips. Thicker strips (.007-.042) are used for spar caps. The thickest strips (.030-.060) are used for trailing edges.
Free Flight: Duration
FOR THE LAST FEW months I've talked about the uses for carbon fiber and how to get started with "high-tech" construction. If you have any questions or comments about building with carbon fiber, please drop me a line. A stamped, self-addressed envelope included with your letter will be appreciated (and you'll get your letter answered that day, not the next time I happen by the post office). One of the best uses for carbon fiber is for fuselages and tail booms. The early "skinny" booms were often remnants of fiberglass or carbon fiber fishing rods; they were usually too heavy and never exactly the right size. Then modelers around the world began to try their hands at making carbon-fiber tailbooms and fuselages. The big breakthrough came when modelers discovered that the thin aluminum sheet popular for F1C wing skins could be combined with unidirectional carbon fiber to make a strong, light, and stiff boom. These were much better than anything that you could make using traditional modeling materials.
Free Flight: Duration
CO2: MY YOUTHFUL memories of CO2 motors is somewhat limited. I do remember seeing one or two around, but I don't ever remember seeing one in the air. (I do, however, remember the Monogram CO2-powered rocket - it looked like a V-2. These didn't use a motor; just a CO2 cartridge stuck in the back of a solid balsa model. The rocket ran horizontally along a wire, guided by a couple of eye hooks in the body. Lots of fun.) During the last few years I've been noticing a considerable number of articles about CO2 motors and models in several newsletters, in the NFFS Digest, and in Vol Libre. Many of these articles are the work of one man: Fritz Mueller of Columbus, Georgia. The articles have covered the fine points of loading the tank to get the maximum amount of liquid CO2 into the tank, complete with pressure-versus-temperature graphs.
Free Flight: Duration
FREE FLIGHT FORUM 1997: Don't let the date mislead you - this is the latest edition of the British equivalent of our NFFS (National Free Flight Society) Sympos. What the British do is have a formal presentation of each of the papers, usually in early January (1997 in this case). Then the papers are published, usually late in the same year. The 1997 Forum, edited by Bryan Spooner and Martin Dilly, includes a broad range of papers - most with a practical (rather than theoretical) bent. Here's a rundown of the articles: ( Dave Clarkson, back flying Free Flight after a long turn at Team Racing, gives his personal thoughts on building and flying Slow Open Power. Known as SLOP in the United Kingdom, this is very similar to our Nostalgia Gas events, but without the requirements to use a pre-1955 design. Basically, the SLOP rules call for a plain-bearing engine (3.5cc maximum size), running on suction (no pressure or pacifier fuel systems). Gadgets such as auto surfaces or engine brakes are banned. This article should be of interest to anyone flying our Nostalgia events.
Free Flight: Duration
TIMERS: The first gas model I built, back in the mid-1950s, was a 1/2A Zeek. Although I can't remember which of the Atwoods I used, I well remember the eyedropper tank. Back then, there weren't many options to limit engine run. Eyedroppers or coils of clear fuel tubing allowed at least some indication of the amount of fuel. You'd start the model, adjust the needle valve, refill the eyedropper, and watch `til the level got down to a predetermined mark (often predetermined not by test runs but by "that looks about right"). Then you'd launch the model and hope the engine ran long enough to get the model up high enough, but not too long to rate a dreaded overrun. It wasn't very accurate, but the engine run was 15 seconds handlaunched or 20 seconds ROG (Rise Off Ground), so a few seconds less than that wasn't that bad.
