Any Color You Like So Long As It's Black

I have a couple of race wings and a twin boom pusher and few other airframes in the hanger.  What i was looking for was what I call a 'Sport Cruiser'  A sport cruiser is a wing that can be used as a mid to long range cruiser but is still agile enough to do some proximity and aerobatics with.  Let's breakdown the requirements.  

Flight Time

My first consideration was cruising.  I wanted a wing that I could use to do some exploring with.  Something that I could rig with a long range system and use for extended flights.  My flight time goal was 30 - 45 minutes at a reasonable cruising speed.  This is actually a very complicated requirement, it governs a lot of aspects of the design.  One of the most important factors governing flight time is fuel, in this case, mAh.  Battery capacity will dictate the weight of the wing and thus the amount of lift needed.  This will be a big part of the design.

Wingspan

I wanted to have a sizable wing.  A larger wing will make it easier to carry more weight and will tend to be smoother in the air.  I have a few 36" wings so I wanted something larger than that.  I intended to build the wing out of EPP foam so I also wanted to make sure that the wing components could be efficiently cut from a standard size of EPP.  This will keep the materials economical.

Speed

I wanted the wing to have a wide speed envelope.  I wanted a cruising speed of 35-40 mph and play speed the 60 - 65 mph. This will have a lot bearing on airfoil selection and wing structure, not to mention motor selection.  


HD Video

I really wanted the wing to able to carry a GoPro camera or at least a GoPro Session.  This is very important because most flights are shorter than you would want and it's great to be able to replay the video.  Plus its hard to share the FPV experience with others without good HD footage.

These were my basic set of requirements.  As I progressed through the design I came up with additional 'wishes' that helped guide the design.  With these requirements in hand I set out to design my wing.  There are several ways to do this.  I spent a lot of time researching designs by other manufactures, however I realized that I wanted to know why they made the decisions they did.   As an Engineer I would never by satisfied using aspects of other designs without understanding why it was designed that way.  This meant a crash course in aerodynamics.  

Another friend, FPV pilot and mechanical engineer  Adam Proulx suggested and eventually found a copy of a text book he used in college.  Basics of RC Model Aircraft Design by Andy Lennon is a tremendous reference and is full of RC model design information.  This is important not all the principals of aeronautical design scale well to the model size.  If you are considering designing a model aircraft I woulds highly recommend you get a copy of this book.  It is hard to find but the Internet is a big place and you should be able to find a cop somewhere.

With all of the this out of the way my next post will start the design process.






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