In my last and first write-up about my paper airplane hobby I had put forth two goals. The first one was to build a small, slow glider that I could control with a smart phone. Sadly, I am not the first person to ever think about this. In doing some research if found PowerUp on kickstarter (check out https://www.kickstarter.com/projects/393053146/powerup-30-smartphone-controlled-paper-airplane or http://www.poweruptoys.com/). These goodies are not quite ready for delivery yet, but I am going to order a set and start preparing for a slightly more audacious set of controls.
A Sample of My Fleet of Paper Airplanes
While I am enheartened and simultaneously a little down that I don’t need to “reinvent this wheel,” the PowerUp 3.0 does save me a bit of work and I can concentrate on the stepping up to the other goal – the 100 mph paper airplane. I have decided that I want to concentrate on a flying wing design, preferably a ducted fan model. So I have been playing around with a number of designs and proof-of-concept ideas leading up to some more serious development over the summer…my kids are about three weeks from being out of school. Flying wings have fascinated me since I read a biography of Jack Northrop (founder of Northrop Grumman Corp), which was spurred on by my families involvement in the B-2 Bomber program during the 1980s and early 1990s. While I have not tried to replicate the B-2 bomber’s design you can see some of the influence in a few of the designs that I have put together. Surprisingly, all of these planes fly, though some much better than others. This sample of aircraft was mainly to identify some construction methods and aerodynamic principals.
Laminated Flying Wing with Cutaway View
Among some of the fun items I have been playing with are: airfoil shaping, leading edge twist, dihedral, sweep, aspect rations, center of gravity and lift, and control surfaces. While this first model that I am showing had horrible CG issues (needing the weight of 2 quarters at the nose to get it close to correct) it shows some of the laminated construction techniques that I will employ as I move on to larger models with and attempt to use specific airfoil designs. It its credit, this design made from 5 sheets of 20, 60, and 100 lb paper and white school glue (with the underside covered with clear packing tape for show) is incredibly stiff.
Rubber-Band Powered Ducted Fan
Another one of my fun efforts was to start designing a rubber band powered ducted fan unit – measuring 4 inches long and 2.5 inches in diameter. This proof of concept did not work all that well because of poor bearing surfaces, but it was not a complete failure. The fan section includes three separate fan components that were inspired by the design of the GE90 bypass fan (the geometry of the GEnx and LEAP 1 were a little too difficult for me to work out without using some advanced CAD features. Each fan has eight blades and are made from two pieces of 60-lb laminated paper and are attached to the an empty ink cartridge from a pen (which also provided the shiny spinner cone on the front). The fan duct is another issue that needs to be improved upon. Getting the paper tube the roll circular proved a bit tricky, but this will be fairly easy to solve the next go around. I think that with some nylon washers, better rubber strands (not bands) I will be able to make a much better second prototype capable to producing more thrust for longer.
To be sure, I have no plans for using paper to build the ducted fan section of my BHAG design, but it provides me a chance to explore some propulsion concepts that I can build upon. Additionally the paper design could provide the powerplant for a number of smaller designs to support replica jet designs. I will post some plans for that when I get them done.
The 3-foot Paper Wing
The last item for this posting is an extension of the flying wing work and showcases some of the design methodology I have developed for the smaller flying wing. The wing span on this design actually measures out at close to 3 feet wide. To help it fly a bit farther the non-powered variety I have scavenged the drive unit from a cheap AirHogs “Zip Wing” kit with a folding prop.
The powered configuration has yet to fly, but in its current form reminds me of some of the pylon and slope soaring sailplanes that I used to read about. I really do not want to have the rear stabilizers on there, but until I have an active way of turning this beast around, it will have to suffice. I am actually concerned that when I let this thing go it could travel a lot farther than I want it to. This side shot also illustrates the airfoil shaping and to a lesser degree the leading edge twist, which is intended to mitigate “tip stall” which flying wings can be prone to. Some other features in this paper airplane wing are the reinforced leading edges and the over-wing skin, which keep it from looking like a K-style airfoil.
I am going to go get some rechargeable AAA batteries and give this thing a go. It it is successful, I may print out some “carbon fiber” paper and make this project look a little more related to the main focus of the blog. Hopefully it won’t land in a neighbor’s backyard…I think the last time I knocked on a neighbors door to retrieve something like this I was about 12 years old.