Fix it right. If you are at the field, and accidentally pierce the wing covering (or covering anywhere else for that matter), then I would agree, a light packing tape (not masking tape, duct tape, or that tape with fiberglass string in it, just that thin layer packing tape available at such places as The UPS Store and so on) would be a good TEMPORARY FIELD fix. This is so you can continue flying.

After you are done, and head home, remove the tape and FIX IT RIGHT.

Get a roll of ultracoat or monocoat or whatever.. that either matches the covering or is a contrast to the covering on the wing. Cut a patch out that is slightly bigger (perhaps a half inch) than the hole OR cut a patch in the shape of a stripe or a star, a design, in other words.

Trim off the fray covering within the hole area, clean the area to be patched with alcohol and let it dry. Make sure that the area is oil free (oil from the engine exhaust), then place the covering over the hole and carefully iron it on. If done right, it can look better or become invisible (if the covering matches).

As far as the fuel is concerned, hey, get what your local hobby store has in stock. 10%, 15%.. will all work just fine. A more critical issue with the fuel is the oil-blend content. Most oils are a blend of castor oil and some other type of oil. Make sure that this oil is at least 18% oil. The blend is not that critical, but it should have some castor oil, but the overall percentage should be at least 18%. Most are 20%. The fuels that have more oil blend is usually for helicopters, and often has a higher nitro content. So, 10 to 15 % nitro plus 18% minimum oil is a good choice. You will be paying around 11 to 14 dollars per gallon for this.

CGr.