COORDINATOR: TBD

PILOT MEETING: 10:00 AM

LOCATION: Sod Farm

The quest for new membership has been going on for some time. We are constantly looking for the ways to attract the youth, competing with little league, TV, MTV, video games, the mall, and girls. It was bad enough when we just had girls to worry about.

Maybe we are fishing in the wrong spot. If we look back over the recent past and ask where the new members we have attracted have come from, we find that they are the Seasoned Citizens. Many have not built a model plane since they were a kid. Many never built one, but through a friend were introduced to Radio Control and soon became hooked.

Consider the demographics, millions of baby boomers reaching retirement age in the next few years with time on their hands and cash to play with and a mind set that lets them indulge themselves and a driving need to do something different.

What will they be looking for, now that the job career is behind them?

They will be looking for social interchange, their minds will be looking for new challenges, they have an inherent interest in the past (aviation history that they grew up with and a chance to relive some of it with models of the vintage planes the vaguely remember hearing about), they will be looking for something fun to do, something that can consume the energy they brought from their jobs.

I talked with some new club members (most of which come from the Senior ranks), those that have just started in model aviation and what attracted them. It was in most cases through a friend who brought them to the field or they happened to wander into his work shop or saw him loading planes in his car. Once they joined the group they were hooked, the frequent get-togethers at the field, the mutual support on building projects, the travel to fly-ins and the general feeling that they were more than a couch potato and doing something just a bit more challenging than could be handled by the average bear. They were doing something fun, interesting and physically and mentally stimulating, yet something that they could do as the infirmities of age crept up on them. While golf scores may start to ebb, model building skills seem to flourish with age. Something for nice weather and something for those cold rainy days. Something they could look upon with pride of accomplishment. Yes and maybe even a break from the regiment of golf everyday, something they could do if, when and where they felt like it, in the solitude of their workshop or in the social whirl at a busy day at the field. Something that could totally consume them.

So we bring in the rare 14-year old and then loose him in a couple of years to college, job, family—for maybe a half century before he has the time and money to "get involved" in R/C again. Let’s look to those that have passed that half century and have the time, inclination, resources and interest once they discover the hobby. Most of them will be good for at least another 20 years or more to enjoy the hobby with us.....and there are a lot more coming along behind them.
At our mall shows in the past the only real interest was shown by those OUTSIDE of the age range 6 to 60. How about a great article in AARP magazine? Stop by your local Senior Citizen center for a show and tell on Radio Control. I know the old-timers have taken over the hobby, (have you looked at the local golf course lately) but we have a steady supply of them well into the next century.....and they do have the time to keep the grass mowed and facilities in top shape and raging hormones won't distract them (well most of them). Even today's teenagers will grow older someday and find that the boob tube just doesn't hack it any longer and Betty Lou is getting a bit long of tooth.

We have the right bait, we just have to fish in the right hole.

IMAA 18939

by Clay Ramskill

We finally master our high wing trainer—or trash it, whichever comes first. Maybe then we build a shoulder wing plane.
Only after we are somewhat competent at flying do we try flying a low wing plane, and then with white knuckles and shaky knees. WHY? Just what is it about low wingers that make them “tougher” to fly? Are they faster? No! All other things being equal, there’s virtually no difference in drag, or therefore top speed. The illusion comes from designers’ choice—they tend to put faster airfoil sections and lower aspect ratios on low wing planes, making them speedier.

Low wing planes do have several characteristics, compared to high wingers that make them more suitable for higher performance aircraft.

1. “Nicer” (and quicker) roll response. This comes from the relative placement of the Center of Gravity, being closer to the natural roll center of the wing. The CG will be at or only slightly above the roll center of a low wing, but well below that of a high wing. Assuming at least a little dihedral, the roll center of the wing will be slightly above the center of the wing.

In a roll, the wing (providing the “power”) wants to roll about its own roll center. The rest of the plane (the “resistance”) wants to roll about the CG. The wider the distance between roll center and CG, the funnier-looking is the roll (i.e., “non-axial”).

2. The low wing lends itself to a less stable stabilizer position, leading to more pitch maneuverability. With a high wing, it's simple, and natural, to have the stabilizer well below the wing. When the nose is pulled up, the stab drops down well below the wing’s downwash, and becomes increasingly resistant to further AOA increases. This is great for stability, and makes stalls less likely.

The opposite is true for the low winger—or a pull-up, the higher stab drops into the wing’s downwash, making further AOA increases easier, and the plane more maneuverable.

3. The low wing reacts more neutrally to power changes. Our old high wing trainer, with the thrust line very low, will respond by pitching nose up when power is added, nose down if power is reduced. This contributes to stability, with the nose going the way we want it to on a trainer. On the other hand, the low winger will be more neutrally stable, without much pitch reaction to power changes. The low winger will also be more wind “resistant” on the ground, a function of wing height above the wheels. The high winger will naturally be more “tipsy,” reacting to wind while taxiing and during takeoff and landing.

We must all understand that we're only talking of tendencies here. There are many other variables that have an impact on the characteristics involved—the designer can juggle these around to get the desired handling. But wing placement is definitely one of the biggies when it comes to establishing how a plane is going to handle.

from Clay's Newsletter Editor Helper
courtesy of Clay Ramskill, Arlington TX
Seven Towers RC Club

from the Net, by Joe Wagner

Contrary to common belief, ammonia doesn’t really make balsa easier to bend. True, ammonia has long been used by industrial “wood formers” to soften hardwood for forming tennis racket frames, chair seats, and that sort of thing. However, (1) the ammonia is in concentrated gaseous form, so strong that one breath of it would sear your lungs; and (2) it works by temporarily plasticizing the lignin “binder” in the wood.

Household ammonia doesn’t really help in forming balsa because (1) it’s merely a weak solution of ammonia gas and (2) balsa contains practically no lignin anyway. (That’s one reason it’s so light.)
Household ammonia appears to soften balsa. That’s because its detergent action makes its water content soak into the wood fast. Few modelers realize how slowly plain water penetrates balsa. It wets the outer surfaces fast, all right—but in doing so, the wood cells swell up and produce a barrier against further moisture penetration. At Veco in the 1950s, we used a wet process for die-cutting that eliminated nearly all “die-crunching” problems. But to make it work we found that the wood had to be soaked all the way through. For 1/8” x 3” x 36” medium-hard balsa sheets, that took at least 24 hours.

We tried an ammonia/water solution to expedite the soak-through. That worked! However, we also found that ammonia makes an excellent fertilizer for various molds, mildews, and fungi. They thrived gloriously between many of the wet sheets of balsa—which, as you might suspect, took about as long to dry out as they had to become saturated in the first place. One further detriment to the use of household ammonia for model-building purposes is that some if not all brands you can buy at your supermarket contain other “ingredients” besides NH3 and H2O. Bobrick’s Cloudy Ammonia (for example) has detergents and stabilizers added, which cause polyvinyl type cements (e.g., white glue and “aliphatic resin” glue) to curdle rather than cure.

Plain water seems the only sage “bending enhancing” fluid for balsa. True, it takes a long time to thoroughly penetrate the wood. Hot water works faster, but even that requires about four hours to truly saturate 1/16” sheet balsa. But when balsa is really soaked, you can just about tie knots in it without its breaking or splitting. I’ve formed severe compound curves with it—such as a one-piece fuselage top for a 3/4” = 1 ft. scale Lockheed 10A “Electra”—that would have required strip-by-strip planking by conventional construction methods.

True, there’s a drawback to working with soaking wet balsa. It expands when wet and shrinks back again as it dries. For medium-weight wood, the lengthwise expansion of saturated balsa is about 3/4 of one percent. That’s not enough to make trouble, at least in the size models I build. But across the grain can be a different story! There the expansion can be as much as ten percent.

That’s more than enough to cause problems. I once made the mistake of sheeting the leading edge of a big control line stunter with sopping wet 1/16” x 3” balsa sheet. When it dried out, the shrinkage produced “scallops” between the ribs, almost as bad as if I’d covered the wing with wet Silkspan.

All this goes to show that model building is an art form, requiring knowledge, patience, finesse, and even a modicum of good luck. But to me that’s the fascinating part of the activity. (I’d rather spend time constructing my own models than cash buying craft built by others. As far as I can see, there’s nothing educational in spending money . . .)

from SAM 8 Speaks
Ted Katsanis, editor
Bellevue WA

by Bob Smith Industries
This article is originally from the Sky Corral RC Club Newsletter, Pueblo, Colorado, Peter Illick, Editor.

A: Several factors can affect the curing of epoxies. Not mixing equal parts is the first suspected cause of problems, but since the 50-50 ratio has a plus or minus tolerance of about 10%, this is rarely a problem. Sometimes modelers will intentionally mix in extra hardener. This is not recommended! The improper ratio can result in brittleness and/or loss of strength in the cured epoxy. Incomplete mixing of the two parts will also cause problems. Spend at least one minute to thoroughly mix the two components.

The vast majority of problems with epoxies are temperature related. Most epoxies need an environment that exceeds 70 degrees Fahrenheit while they are curing. Heating the epoxy hours after mixing will not solve the problem of improper curing. The temperature must be correct during the initial curing time. Maintaining proper temperature control in your workshop will solve most epoxy problems, however, since the majority of workshops are garages where work is mostly done at night when temperatures are low, temperature control can be impractical. In this case there are two options. First, the two epoxy components can be preheated before mixing. We have found that heating heating epoxy bottles without their tops in the microwave oven to be the quickest method. The bottles should be heated to where they are only slightly warm to the touch, which usually takes 10-20 seconds, with the resin (black top) taking less time. Do not mix components that have been overheated because the cure time will be greatly reduced.

Q: My 30 Minute Epoxy cures in only 10-20 minutes. Did I get mis-marked bottles?

A: The minute designations on our epoxies are the amount of time one has before the components start to cure to a taffy-like consistency when mixed on a flat surface (such as the flexible plastic top to a coffee can). higher temperatures will reduce the working time. As epoxies cure, heat is created. If a larger amount of epoxy (1 oz. or more) is mixed up in a cup, a mini-reactor is created which concentrates the heat of curing which causes the epoxy components to kick-off faster which creates more heat which further speeds the curing, creating more heat and so on and so on. on warm days you can end up with a smoking blob. lay down parallel, equal lengths of each component before mixing them to get consistent results. The 20 minute designation of our finish-cure takes into account its being mixed in larger quantities in a cup.

by Clay Ramskill

This subject is tough, assuming we want to stay clear of complexity. To get into the nitty-gritty of drag reduction, we need a wind tunnel, some heavy computations, and a whole bunch of witchcraft!

So we'll stick to some more basic principles, and leave the name dropping and number crunching to someone more learned than we are! We do, however, have to make one distinction: drag due to lift. That is pretty much separate from the rest, because it's strictly a function of lift. The more lift we need, the higher the angle of attack our wing must operate at, the more lift drag we have. And once our wing area, shape, and airfoil are established, there's really only one control we have, and that is the weight of the plane.

Put simply, the heavier the plane, the more this form of drag will degrade performance. Having gotten past that, there are several other drag components to look at: Cross-sectional area, form drag, skin friction, interference drag, and projections.

Cross-sectional area is easy. The more air you have to push aside as you go through it, the more drag. So we need to keep fuselages reasonably slender, and airfoils reasonably thin. But the size is not nearly as important as shape.
Form Drag: Good streamlining is an area where we can really see some results. What we'd like to see is every component of the plane shaped like a good symmetrical airfoil, or drop tank as seen on jet aircraft. At the speeds we're interested in, a really sharp point in the front is not necessary (that's what you see on supersonic planes!). What is desirable is a nice smooth curvature. Where we do want the pointiness is at the rear. A good, smooth, continually tapering curve ending at a relatively sharp trailing edge or point. The main thing to avoid is abrupt or angular changes in the airflow.
Retracts: The worst contributor to drag is the landing gear. Fixed gear drag can be reduced by wheel pants and cuffs on struts, but retracting gear is the obvious solution. There are, however, weight, complexity, and expense penalties.

Skin Friction: First, the less skin, the less friction! Rounding corners not only cuts form drag, it cuts the skin area. Round forms enclose the most interior volume with the least skin area. A smooth skin cuts drag. Dirt, rough covering overlaps, and covering wrinkles all increase drag. You won't do much better than good sanding and covering! We should point out that sharp corners, even when aligned with the airflow, will tend to increase turbulence and produce more drag. A rounded fuselage is less draggy than a square fuselage. The same goes for wingtips.
Interference Drag: We did a nice little wind tunnel experiment in school. We measured the drag of a fuselage, and then the wing. Then we put in the wing and fuselage attached together. The combination had extra drag beyond the sum of the components!
The interference caused by projecting objects (like wings, landing gear, gear struts, stabs, etc.) can usually be reduced by the use of fillets. These were quite pronounced on WWII fighter wings, as on the Spitfire and P40 with the interior square corners rounded off, carrying the rounding well aft of the wing. You'll see these on pattern and racing planes.
Projections: The best solution to projections is to get rid of them! Retract the landing gear, hide the control horns, enclose the radio antenna, countersink the bolt heads, etc. Cowl in the engine, and use an enclosed muffler. Look at a competitive pattern plane. You'll see all of these features.
Drag reduction involves many details, all of which add up in achieving your goal. If you want to go fast, get out the sandpaper. But remember, we need both a smooth skin and a smooth form!

from Clay Ramskill
7 Towers RC Club