Tuesday, March 20, 2018

I Think I’ll Just Wing It. Pt.4

Let's talk Fuselage.

When building the Fuselage for an airframe you have a few things to consider or at least I did when designing this. First off how will it land? Sailplanes and gliders usually do not have any landing gear with the exception of a nose roller to help it slide. In the RC world, a lot of aircraft are called "belly landers" They might be somewhat scale planes, or profile scale but no gear. Why? Well for one it saves weight but another issue is the punishment landing gear goes through on RC aircraft. One hard landing on some planes tears into the fuselage from the way it is designed. Even in a perfect landing long grass can be a real challenge not to nose the plane over breaking props, motor mounts etc. Imagine in scale, you are landing in a 10' high cornfield. So when there is no gear you hand launch, which can take a bit of practice and when hand launching pusher prop types it takes a bit of a dance to keep from getting bit. This all depends on where you have available to fly, I am using a landing gear since I have a few hard surfaces available I can take off and land from.



The next thing to consider is where your gear will go since I am doing this from scratch I have no point of reference as to where the weight of gear should go, the center of gravity etc. So I need to not only allow room for gear but have some latitude to move it around to achieve a proper center of gravity balance.



I used a basswood stick 6mm x 610mm as the rear fuselage, the foam I add is only to lessen drag a bit and give me a wing mount. I used some lightweight plywood for my motor mount/firewall. The stick is basically the datum line of the aircraft.



The landing gear is .039 music wire bent to give some shock absorption to my gear. I used some scrap light ply to make a reinforcement to sandwich wire to main stick. I grooved stick slightly to allow the wood plate to fit flat. I used regular Titebond 2 wood glue. Keep in mind using only glue you need, it is amazing how much gratuitous use of glue can add, and we want as little weight as possible added.








I could put a small section of bent music wire in the tail to make a taildragger but sometimes trying to steer on the ground can be a challenge when all you have is the rudder and prop wash to steer. I will show later how I make the tail steerable.

Lastly, how will the main wing mount? Wings have incidence which is the angle of attack it has, higher on the leading edge with a 4-7 degree drop at the trailing edge of the main wing. I am going to use foam board sides of the fuselage to create the wing mount and its incidence which I am going to go with 5 degrees.

Next will be the Tail Surfaces...

-Hobby Dude

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