Landing Gear Design Part 2: Parts and Mechanisms
Updated: May 20, 2020
Now that we know what types of landing gear, brakes, and suspension that we are using, it is time to draft out the mechanisms by which they work, as well as selecting the manufacturers and exact parts to use.
Originally, we had decided on using cub style landing gear; however, we encountered some serious issues. At this point, we had already started drafting up our landing gear, but we had a serious concern: our wheel was so far forward that we had it well in front of the leading edge of our wing/front column of our fuselage. Here’s why this problem came up: in order to determine where the wheel should go, we needed to know the fore and aft CG limits. There was no way to calculate these at this stage in the process, but we did know one thing: our actual CG, which should align perfectly with our center of lift, or ¼ chord. That means that we can draw the two lines (at 25 and 15 degrees for aft and fore CGs respectively) from points equidistant from the ¼ chord, and then move them in and out by the same amount until they touch in a realistic spot to put or wheel. This caused our initial drawings to look like the screenshot below:
The reason this was a huge concern is because when landing or at rest, the weight of the plane is creating a strong torsional force at the brackets holding the landing gear on, which is unacceptable, as it will likely break the brackets or landing gear. The ideal layout would put the axle directly under the leading edge/front column of the fuselage, as this would put all the forces directly up into a very strong joint. We decided to go ahead with this form (see below, taken from the Affordaplane) as the wheels will still be in front of the CG, so the gear should still work.
After all this fuss, we started questioning whether suspension was really necessary and if we were approaching design the right way. We decided to reach out to our friends at the HomeBuiltAirplanes forum to see if they had any advice. We got two main takeaways from the forum: try out Wittman style and read Landing Gear Design for Light Aircraft by Ladislao Pazmany. After reading the whole textbook and taking notes, we met again to discuss new possibilities. We ruled out cub style gear, as they would be overcomplicated and weren’t at all necessary. Our favorite options at the time were Wittman style with carbon fiber, a sort of cub style gear without any suspension, as seen in the Affordaplane, and an amalgamation inspired by the Affordaplane’s gear, but with bungees near the axle, as seen in the Nieuport 11. We eliminated the Wittman style, as there was just too much that could go wrong with only single bars of material holding on the gear. We decided to create gear similar to the Nieuport 11’s, as they are basically the same as the Affordaplane’s but with about ½ lbs extra weight and $20 more of material, with the benefits being actually having suspension.
For our main wheel we settled on a Black Max brake kit, as it came with everything except the ATF. For our tail wheels we used pneumatic tail wheels from MatcoMFG. We will connect our tail wheel to the tail of our plane using spring steel. Our tail wheel will be lockable during takeoff and landing with a pin, so as to avoid most ground loop tendency. Our tail wheel will also be connected to the rudder with springs so that it can be steered during taxiing.
*Editors' note: the thought processes and design choices presented in this article don't necessarily represent those implemented into the final design and are subject to change. Flight Club Aerospace is a group of amateur students with no formal education in any fields of engineering. We present this information for educational purposes only, with the understanding that it is not to be re-created without adequate professional oversight and mentorship. For our latest designs and updates, please see our most recent blog posts.