Weight for packing tape to cover wing
Iíd like to present some data for weight added to wings by packing tape covering. Jackerbes likes to use tape to cover wings, and recently posted his tape hinging technique
The wing Iíve covered that way recently spans 46 inches and has a chord of 7.2 inches with trailing edge stock attached. It was made from blue foam wire cut cores for a Thermal Panther glider from Steelhead. It has a flat 23 inch center section and raised tips. At 2.3 sq feet, itís a bit smaller than the KFm3 wing in the BB42 design. I covered it for practice before I cover the 48 inch wing for my BluBaby 42. I recently showed a picture of my dihedral joint for that wing.
After the spar was installed in the 46 inch wing, it weighed 140 grams. Putting a balsa trailing edge and some thin plywood at the wing center added 8 grams. Putting a strip of fiberglass strapping tape along the leading edge and covering the trailing edge with newsprint and WBPU lacquer added 20 more. Finally, putting the packing tape on top and bottom added 27 grams, for a total of 195 grams or 6.9 ounces. The packing tape weighed less than 14% of the total.
The 48 inch wing weighed 146 grams at the spar only stage, and will have an 8 inch chord with trailing edges attached. Since that makes it 2.7 sq feet, covering it with packing tape should add about 32 grams. The total covered weight should be 7.5 ounces. With only one dihedral joint, itís a little lighter per unit area than the flat center wing. The area for the KFm3 wing in the original plan is only slightly larger than for my 48 inch wire cut wing, so Iíd expect covering weights to be very close.
Sir Clive, what is your wing weight and all up weight (with battery)? Nice job of shifting weight forward.