Hello out there.
This is a side development that came out of a previous article of mine "One Sheet No Waste Flying Wing..." This idea came to me after trying to fly an Old Speedster that was made per plans inside the local school gym. It was my frst flight after 15 years off and I was a little rusty. The main problem, hawever was that my fingers DID remember. I had never flown with two chanel, rudder and elevator controls. My instincts took over and I was trying to bank and turn with up elevator. Well that does not work as well without ailerons. I ended up doing a hammerhaed stall and nosing in hard when I did not have enough room or time to recover. The Old Speedster got banged up enough to end my session so I went home. As usual I started working on the repair before I sat down. As part of the repair session I decided to add ailerons to the Old Speedster. I have not flown it again but I have every confidence that I will be OK with the change. It looks like this:
In the mean time I decided to try flying a Nutball in the gym. I am working with the Physics teacher who is adding a RC module to his Phisics classes. We are planning to use the three-plane kits (Nutball, Delta and Flyer) as the basis of the class. I wanted to see if it was practical to have students try to fly in the gym. I had previously built a Nutball per plans and decided to convert it to elevons for the purpose. That worked out great. The plane flew fine and I was able to make a couple of circles before I ran into a wall, my rusty reaction time catching up with me. As it turns out the space is too small to be practical.
The Nutball flew so well that it caught my attention. At that time I was working on the series of flying wings that used one or two full sheets with no waste. I ended up with four designs that are given in the other article. I decided to try a One-Sheet No-Waste version of the Nutball. This is the result:
I simply disconnected the rudder horn and stuck a scewer in it to "fix" it in place. I then split the elevator into two equal parts and reattached the push rod to that side. I reset the radio to "elevons" and it was ready to go.
The Nutball flew so well that it caught my interest. At the time I was working on another article that included four flying wing designs based on the "One-Sheet No Waste or Two-Sheet No-Waste" concept.
The thought occurred to me that I could make a larger version along the lines of the "One-Sheet No-Waste" concept. I laid out the largest half circle that would fit on each end of the 20 X 30 sheet and then connected the two with straight lines. I left 3/16" trimming room all around so my length is actually 19 5/8" instead of 20" (which is the same size as the original Nutball). My overall width is 1 1/2 times the Nutball or 29 5/8". I used the same percentage of the width for the dihedral folds as the original design. The orignial ones were about 4 5/8 " which made mine (X 1.5) 7". I reduced the width of the elevators from 3" to 2 3/4" since they are not curved in as much on the ends. I split them in half and made elevons as I had done on the original Nutball modification. I used all the same center layout for the pod slots and servos. In keeping with the no-waste concept I used the corner cup-offs for the tails. I just did square cuts where the radiuses went to 1" wide and a small angle cut to allow for the elevon throw. I also did small angled back cuts where the tails meet the fuselage. Because the original circle layout was pretty accurate the 4 tail pieces were pretty uniform. I used the FT Delta tail template (about 15 degrees) to set the inner pair and a 30 degree triangle to set the outer two. They are each 4" apart. I fabricated a tail skid using a scrap of foam board and bent a piece of flag wire to make a spring skid. I am using the same pod and landing gear that I used on the original Nutball.
Here is what I ended up with:
Here is the spring skid:
The skewer is making the hole for the bent part of the wire. There is also a generous "V" slot along the bottom edge to glue the wire into.
Here is the expensive high tech protractor I used for my circle layout:
Super Nutball now has retracts:
This is a proof of concept installation and still needs some refinement. I also have to work out tricycle gear which most or my models will need.
The only problem I found with this was that it tended to over-rotate with the weight of the plane. The servo gears and arms are plastic and tend to flex under load. I fixed that problem by adding a pair of wooden wedges behind the lug on the gear. Like so:
They are small pieces of 1/8" lite- ply cut to match the angle of the wire at full extension and glued down with hot glue. They prevent the wire gear from over-rotating. The proof of concept installation is now fully functional.
Look for a separate article "Wire Hanger Retracts" in the near future.
I am developing two methods, one with the wooden wedges and one with a more complicated set of wire bends to accomplish the same effect without the wedges.
I hope to have it submitted by 2-28-14. It may take a few days to get approved and posted.