Ailerons and Engines
Yanking and banking soon possible
If you have good health, consider yourself lucky. I have had some health challenges of late and am far behind schedule, but enough about me.
We have ailerons and engines. Before the doom and gloom set in, and after my last post I made a set of ailerons and they are quite handsome, if I do say so myself. The construction method is somewhat similar to the wing ribs, foam rib cores with sheetmetal capstrips. A 1.5” tube is the spar and a ½” tube for the trailing edge with sheet metal to make a pointy edge. I designed the ailerons on Solidworks and had a full size template printed out. I glued this to a hollow core door to build on, just like my RC modeling days. I made rib locators out of blocks of 2 x 4 and glued them in place. This holds all parts in location and all that is necessary is to drill the rivet holes and pop them in place. The ailerons are very strong in torsion, more so than I expected, without using triangular gussets like on the Lazair. In the pictures the trailing edge sheetmetal is only sitting in place, it is not permanently fastened yet. You can see the end caps, which also are not finished, they need trimming and riveting. A unique aspect of these ailerons is they are symmetric so both LH and RH ailerons can be built on the same jig. To move from one side or the other all you do is install the control horns (not pictured) on the top or bottom of the spar tube to get the alignment to match the aileron control rod, which will exit the top of the wing on the Mark IV.
This symmetric construction required a different pivot setup than the original Lazair. If you will notice the pivot is in the center of the spar tube, via a bushing and stud setup. You will also notice a “pillow block” type bearing on the stud. This gives an illustration of how the aileron pivots. A bearing is installed on the inboard (#6) rib and the outboard tip rib. The inboard stud will float in the bearing. That is it is free to slide inboard/outboard because the stud is considerably longer than need be and will actually penetrate into the inboard rib about an inch, a hole in the rib allows for this by design. The outboard rib will constrain the aileron as it will have a bolt as a stud and will capture the aileron inboard/outboard motion. This end is covered by the wingtip and will not be seen except during maintenance. To install the aileron you will slide the inboard stud into the bearing at an angle until the aileron will fit in the aileron gap of the wing. Lift the aileron into place and align the outboard bearing. Install the bolt and safety. Install the wingtip, connect the aileron control rod, repeat for the other side.
Engines, The Heartbeat of the Bird
I think I posted some time ago that I had intentions of using Hirth F-36 engines on this first Mark IV prototype. However fortune has smiled on me and I have been able to acquire two brand new, in the box, Evolution 7 cylinder 260cc four stroke engines. They are sitting in my closet right now and every now and again I have to open the door to look at the boxes and smile. These engines are an incredible work of art in metal. Check out the website and youtube video links below:
I expect to be the first ultralight with twin radial engines. Maybe a world record? Probably not but really cool never the less. I am making a test stand to break these engines in. I plan to post videos of them running as soon as possible.
Propellers are a beast of another color and have proven to be more troublesome than you might think. I could certainly get propellers for these engines from the RC world, but I think they look out of place on the Lazair, too thin. The problem of what pitch to use is also problematic. I don’t want to buy a dozen props to figure out which pitch is right, that’s expensive research. I really wanted a ground adjustable prop and in particular a three bladed adjustable prop. After many years of research there was only one choice, Solo Props.
More next time,