.049 enigine wing loading weight ??

I'm only aware of two Guillow P-40 kits, the 400 series with a 28" span and the 500 series kit with a 16.5" span.

To calculate wing loading, you need two values: the all up flying weight (AUW) of the model measured in ounces and the wing area measured in square feet. The P-40 wing is a single taper planform, so the area can be roughly calculated by breaking the wing into a rectangular portion and a triangular portion. Calculate the total area in square inches and divide this by 144 --- this gives the area in square feet. Divide the AUW by the wing area to get wing loading, i.e., ounces per square foot. A model that is heavy (has a high wing loading) can be difficult to fly, may have a tendency to snap roll (aggrevated by a tapered wing planform) and will not glide very well at all.

Guillow kits have a reputation of being heavy due to the construction techniques employed and the heavy wood that is included. This can be helped somewhat by substituting lighter wood purchased from the hobby shop and being very careful in the use of glue and paint. Something in the 12.5 to 14 ounce/sq. ft. loading will be flyable. You can get by with a slightly higher loading if used for controlline, but performance will be impacted.

There is a thread in RC Groups on converting Guillow kits to electric --- .

While building a P-40 is certainly appealing, for a first plane with engine, I would be inclined to choose a different model to start and save the Warhawk for a later date.