ZAGI 400 X ELECTRIC, Инструкция по сборке

Страница: 20 / 22

page 19
MODS
The challenge of making any modifications on flying wings is the trade-off between the
advantage and the penalty. Structural modifications made to the airframe should be made
with caution. Since most mods involve adding weight, and more than likely behind the
CG, mods should be avoided. If care is taken in the building process, the weight will be
right on the manufacturers listed weight. Mods made to save weight are the best approach
to building. Having said that, Here’s a few mods that will work in a positive way.
One way to save weight is to use as little of the adhesives and tapes as possible. Instead of
thinking a little more tape or glue will make the airplane better, think how little of each will
it take to make it as strong as it needs to be. Epoxy makes a heavy wing joint and the spar
adhesive. The 3M Super #77 Spray Adhesive will make an adequate bond. Remember,
you’re only bonding to one pound foam. The foam will usually fail before the bond will.
Saving weight on the elevons will reduce the need for nose weight. Some balsa elevons
are heavier than others. Elevon weight can be reduced by shaping. If the elevons seem
heavy replace the elevons supplied with the kit with extra light weight contest grade balsa.
Winglets made of meat tray styrofoam are lighter than the stock material although not
nearly as strong.
Covering materials like Ora Cover or Ultra Kote are heavier than tape. The lighter materi-
als like Solar Film are light but not as strong as tape. There are some problems using iron-
on covering materials. Heat shrink materials can distort the geometry of the wing. Designs
can be made with the color tape by alternating colors in a variety of patterns without add-
ing weight.
Changing the propeller to a different pitch or diameter will require a prop adapter. Once
again that the dorky little white Gunther prop supplied with the kit tested better on the
Zagi-400 motor than all other props available but you have to remember to reverse the
hub. The Zagi-400 and the X are supplied with a balanced power system. Changing the
prop will change the load on the ESC and the battery. The Zagi-20 ESC is rated at 20 amps
continuous. The Zagi-400X with a 1700 mAh battery and the stock prop draw 12.5 amps
at full throttle. So if the prop diameter or pitch is increased, the load could exceed the
range of the 20 amp ESC. Trial and error can get expensive. The way to prop electrics is
with the use of a watt meter. Astro Flight makes a “Super Whattmeter for outdoor R/C
models” for $55.00 from Trick R/C. This device will keep the smoke from escaping from
the speed control. Another useful tool is a tachometer. Cermark makes a good tach for
cheap. A simple thrust meter can be made with a small postal scale calibrated in ounces. A
test stand setup with a wattmeter, a scale and a tach will take the guesswork out of balanc-
ing electric components.