OK, another one.
I'm thinking about different structural configurations for a landing gear. Up till now I've assumed the properties of the Grove landing gears, instead of endless calculations on a design by myself. Compared to the closest one (the Starduster landing gear), I'm looking at around 65" width, 40" height and a horizontal section of 20-35" and a weight of probably just over 50 lbs (excluding everything else) for a MTOW of 750 kg. I want to conform with the Far/EASA regulations for LG design, though I must admit my calculations are energy-absorption only, don't know static strength.
I've ruled out oleos and pretty much everything that moves or can break. So flat/round springs it'll be.
Low drag is very important to me, so a low-drag airfoil shape is necessary. Almost every normally used landing gear can easily be fitted with a thin glass fairing, so that's no problem, though thinner is better.
After running the numbers I got pretty comparable results for alu (the Grove gears) and flat steel springs. The steel is a bit thinner, but getting hold of it is pretty complicated (bending, heat-threatment).
George wrote a nice how-to about making a composite landing gear. Running my numbers with a carbon gear it came out at just over half the steel/alu weight and a bit better while using Graphlite. A nice advantage is that it can be made pretty flat, such that you have more deflection (less springy) and lower drag.
That got me thinking. A major part of the material, whether it is steel, alu or carbon doesn't do a whole lot, except handling the shear. For the beam a landing gear basically is, you should have most of the material on the outside, not have a massive beam.
Why not make a landing gear a la the Rutan method? Foam airfoil shape, beefy sheer web and spar caps and then wrapping it in a couple of layers of carbon. Any thoughts about this? Does gauge thickness defy this idea?
How about a foam that's wrapped in carbon, so you have a "hollow" tubular carbon gear?
I'm thinking about different structural configurations for a landing gear. Up till now I've assumed the properties of the Grove landing gears, instead of endless calculations on a design by myself. Compared to the closest one (the Starduster landing gear), I'm looking at around 65" width, 40" height and a horizontal section of 20-35" and a weight of probably just over 50 lbs (excluding everything else) for a MTOW of 750 kg. I want to conform with the Far/EASA regulations for LG design, though I must admit my calculations are energy-absorption only, don't know static strength.
I've ruled out oleos and pretty much everything that moves or can break. So flat/round springs it'll be.
Low drag is very important to me, so a low-drag airfoil shape is necessary. Almost every normally used landing gear can easily be fitted with a thin glass fairing, so that's no problem, though thinner is better.
After running the numbers I got pretty comparable results for alu (the Grove gears) and flat steel springs. The steel is a bit thinner, but getting hold of it is pretty complicated (bending, heat-threatment).
George wrote a nice how-to about making a composite landing gear. Running my numbers with a carbon gear it came out at just over half the steel/alu weight and a bit better while using Graphlite. A nice advantage is that it can be made pretty flat, such that you have more deflection (less springy) and lower drag.
That got me thinking. A major part of the material, whether it is steel, alu or carbon doesn't do a whole lot, except handling the shear. For the beam a landing gear basically is, you should have most of the material on the outside, not have a massive beam.
Why not make a landing gear a la the Rutan method? Foam airfoil shape, beefy sheer web and spar caps and then wrapping it in a couple of layers of carbon. Any thoughts about this? Does gauge thickness defy this idea?
How about a foam that's wrapped in carbon, so you have a "hollow" tubular carbon gear?
