Quickheads

..... In some areas a sharp corner is desirable and maximum strength isn't required. In these areas a flox corner is used. A simple unsupported glass corner has very poor strength. To strengthen this corner, a triangle of flox is used to bond the glass plies together. The flox corner is done just before one glass surface is applied for a wet bond to one surface. The other glass surface has to be sanded dull in preparation as shown.

HEALTH PRECAUTIONS

SKIN PROTECTION
..... If you work with epoxy on your bare skin, you can develop an allergy to it. This "sensitization" to epoxy is an unpleasant experience and is to be avoided. You generally have to get epoxy on your unprotected skin to become sensitized. If you use a protective barrier skin cream like Ply No.9, or disposable plastic medical examination gloves, the allergy can be avoided. The barrier skin cream also allows you to clean up with soap and water after a layup.
.....The Safe-T-Pox epoxy systems are very low toxicity. However, a few people (about 1 percent) may be sensitive to epoxy. These people can get some help by using doctor prescribed anti-allergy medicines and/or by using elaborate masks/multi-gloves, etc, to reduce exposure. Remember to always use skin protection and never let epoxy come in contact with bare skin, even if you have no reaction to it. Sensitivity is accumulative, such that you may later develop an allergy unless you protect your skin.

DUST PROTECTION
.....Sanding or grinding fiberglass and foams creates dust that can be harmful to your lungs. Use a dust respirator mask for these operations. Disposable dust masks are available at most paint stores.

VENTILATION
.....Mix and work your epoxy in a ventilated area. If your shop is not ventilated, set up a small fan to move a small flow of air in or out. Do not hotwire urethane foam.

HEAT DEFORMATION AND CREEP

..... Several builders have had flying surfaces warp or bend due to being poorly supported until fully cured. Do not hang or support them at each end for long periods as they may "creep" or slowly deform. Store them leading edge down with support in at least three places. Your surfaces can be better protected against "creep" if you post-cure them. Sailplane manufactures do this by putting the entire airplane in an oven at 160°F. You can do it as follows: After you have painted on the black primer put the wing or canard out in the sun. Be sure it is well supported in at least three places along its span. At noon a black surface can reach 140 to 180°F. giving it a relatively good post-cure. After the post-cure, the structure is more stable for warping or creep. If you have a wing or canard that is twisted wrong, apply a twisting force in the opposite direction before and during the post-cure (weights applied to boards,Bondoed or clamped to the surface can be used). Remove the force only after the surface has cooled. A 200 ft-lb torque (50 lb weight on a 4 ft arm) applied twice, once while the top surface is post-cured and once for the bottom, surface, can twist your wing or canard over one degree. The twist correction will be permanent and will stay as long as the surface remains cool (below the postcure temperature). This is generaly referred to as the heat-deformation characteristic of the epoxy. If it is room-temperature cured only, it will soften above 140°F. But if post-cured it will not soften until over 160°F. Heat for post-curing or for intentional deforming can be applied by other means such as heat lamps, hair dryers or electric radiant heaters (house-hold type), however this is generally not recommended, since it is too easy for the homebuilder to get the part too hot and ruin the part. The foam is damaged above 240°F. If you want to use these heat sources, do so by applying the heat very slowly and checking the temperature often by placing your hand on the surface. If you can hold your hand on the surface five seconds without pain, the temperature is okay-three seconds is too hot.

AIRCRAFT MEASUREMENT REFERENCE SYSTEM

.....To ease the engineer's task of defining where things go in these odd-shaped gadgets called aircraft, a fairly standard system of references has been developed. Fortunately the Q2 is so simple that an eleborate measurement system is not necessary. It is, however, convenient to use the standard terminology for reference occasionally and you should be familiar with its meaning.
.....The three basic references are called butt lines, fuselage stations, and water lines. Don't blame us for the absurd names, we didn't set the system up. All three are given in inches from some arbitrarily chosen reference, so, fuselage station 100 is found 100 inches away from fuselage station 0, and similarly for butt lines and waterlines. Being as lazy as anybody else, we abbreviate these as FS, BL, and WL.
.....Fuselage stations (FS) are used to define the location fore and aft on an airplane. To make things easy, fuselage station A is generally located near the nose of an airplane and measurements are made aft. Fuselage stations are the most commonly used of the references and later on you will make a reference mark on your airplane to use as a permanent FS reference point.
.....Waterlines (WL) are used to define vertical locations. Waterline 0 is generally found near the ground and measurements are made up from WL0.
.....Waterlines are utilized in many places to position components or templates relative to each other by leveling reference waterlines with a carpenters level.
.....Butt lines define ,positions inboard and outboard. Butt line 0 is the vertical centerline of the airplane and measurements are taken to the left and right of BL O. Since left and right depends on which way you are facing, it is standard practice to define left and right as the pilot would while seated in the cockpit.
.....Using these three references, any point in an airplane can be described with a fuselage station, butt line, and waterline. Fortunately, your Q2 is so simple that we don't need to locate very many things this way. When you start on your 4/5 scale replica of a B-1 Bomber, this reference system will be real handy.