Preliminary Sizing

Using the information on the engine, for 75% power cruise fuel burn. The previously discussed payload weight and that weight range as a starting guess, we can then use the fuel fraction method as outlined in the Roskam text.  Plus using Breguet's range equation, the total weight of fuel can be estimated to be 271.2 Lbs.  This includes 45 mins reserve.  

 From this we can estimate empty weight.  As the text explains a liner relationship between log of the empty weight and the log of the take-off weight, using the regression line constants for multi engine aeroplanes of composite construction, we can find an allowable value for empty weight.  Comparison of these two methods, showed they matched within 0.04%.  Thus with some confidence I can say the following;

W take-off    =    1984 Lbs   900 kgs

W empty      =    1152 Lbs   522 kgs

W fuel          =     272 Lbs    123 kgs 

Why choose an aircraft of composite construction?  Well....  I think I have found my base model single engine aeroplane for conversion into a twin.  More about that later in the next post.