Andy G
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Lego Technic aircraft engine and landing gear prototype
Andy G replied to Andy G's topic in LEGO Technic, Mindstorms, Model Team and Scale Modeling
I I've been slowly working away on this model aircraft shown below since 2011, but one thing I have been stuck on was how to control the variable pitch propellers remotely. Remote control is required so that only the minimal weight is placed on the wings as a four engine turboprop with a pneumatic gear already has a lot of weight (each wing is 1 kg). I tried using closed loop pneumatics but the compressibility of air meant there was no fine control. Linear actuators would be impractical due to the long drive trains. Closed loop hydraulics is much better-very fine control with really quick response. Also, because no angular loads are placed on the hydraulic master and slave cylinders there is very little leakage of air in or water out once the system has been bled of air-hence the system stays “rigged” for a long period of time. I am thinking of attaching a rotation sensor of some type to the motor as a mindstorms sensor. Then, by hooking up a mindstorms motor to the pitch control master cylinder I will be able to produce a fully governable aircraft motor that has similar operational control modes as a real one (reverse, cruise, taxi etc) Anyway-one day it will be finished! -
Aircraft Nose Landing Gear-new design
Andy G replied to Andy G's topic in LEGO Technic, Mindstorms, Model Team and Scale Modeling
I posted a few videos a while back showing the main gear.- 10 replies
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- lego technic
- nose landing gear
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Aircraft Nose Landing Gear-new design
Andy G replied to Andy G's topic in LEGO Technic, Mindstorms, Model Team and Scale Modeling
Ah it currently has variable pitch propellers with each engine powered by two medium motors, ailerons and a large fowler flap that tucks away nicely. Also has a cabin door with folding stairs. The landing gear is by far the most complicated system-it has a pneumatically sequenced locking brace that replicates a real aircraft. All gears have suspension. I havent built the tail yet but I will get there! Need to finish the controls to the wings, hence my other post showing control system ideas.- 10 replies
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- lego technic
- nose landing gear
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Aircraft Cable Control Systems
Andy G replied to Andy G's topic in LEGO Technic, Mindstorms, Model Team and Scale Modeling
Nice-yeah I think the system has lots of advantages-but the best is it replicates the real thing. -
Aircraft Nose Landing Gear-new design
Andy G replied to Andy G's topic in LEGO Technic, Mindstorms, Model Team and Scale Modeling
Yeah I like the jacks. They use a lot of parts but it looks good when raising the whole aircraft with pneumatics. Very realistic.- 10 replies
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- lego technic
- nose landing gear
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[JFAIR] Simple Prop Plane (WIP)
Andy G replied to D3K's topic in LEGO Technic, Mindstorms, Model Team and Scale Modeling
Very cool! -
Aircraft Nose Landing Gear-new design
Andy G posted a topic in LEGO Technic, Mindstorms, Model Team and Scale Modeling
Hi folks, Here are a few videos showing a new nose gear design for a four engine lego technic aircraft I'm working on.- 10 replies
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- lego technic
- nose landing gear
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Aircraft Cable Control Systems
Andy G replied to Andy G's topic in LEGO Technic, Mindstorms, Model Team and Scale Modeling
Small aircraft use the cable systems to drive the flight controls directly, larger aircraft use the cables to move a hydraulic selector valve near the flight control. The twin otter project is amazing. But did he use push pull cables or string? -
Aircraft Cable Control Systems
Andy G posted a topic in LEGO Technic, Mindstorms, Model Team and Scale Modeling
Hi folks, I've been working on a cable control system for a large technic aircraft I've been building for the last few years. I'm interested to know if his kind of thing has been done before. The prototype replicates the real cable control systems of most non fly by wire commercial aircraft. The main advantage is it has very low friction, low backlash and can be finely adjusted. The video thumbnail shows adjusting rig pins in red. These lock all moving parts in their correct relative positions so the cables can be tensioned. This is how cables are adjusted on real aircraft to ensure the control systems are properly set. The video is here -
Variable Pitch Propeller
Andy G replied to Sariel's topic in LEGO Technic, Mindstorms, Model Team and Scale Modeling
I made something like this a year ago. The problem is the blades aren't very aerodynamically efficient. It does produce some thrust but not enough to be useful. I even geared my prop up using 4 medium motors and had that prop turning at a scary speed but still it wouldn't pull much load. -
Hey folks, Just testing the retractable langing gear system with the engine operating. The propeller pitch control isnt hooked up so I manually change the pitch. havent posted for ages as I had to completely rebuid the wing structure. Really tough to support the nacelle weight. The centre wing box/fuse area needs to be very strong and this took some work, specially given the dihedral angle Its been hard to build the landing gear perpendicular to the ground given the wing dihedral, but it seems okay now. Gear system is the same as my last video pretty much, but it folds up neater with the downlock actuators on the drag brace. Andy
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Great Australian Ute
Andy G replied to Aussie BJ's topic in LEGO Technic, Mindstorms, Model Team and Scale Modeling
Nice suicide door..good to see an aussie contingent here. Maybe we could get together and lament the postal fees for bricklink packages from o/s -
New technic main landing gear design
Andy G replied to Andy G's topic in LEGO Technic, Mindstorms, Model Team and Scale Modeling
the two small pistons attach to the secondary locking brace. Yeah its a pain that they are on the back of the leg I admit. Its just the first design so hopefully Ill make it more compact. The difficulty is the geometry of the locking system. It gets quite complicated in the movement of the gear which limits the placement of the locking actuators. The sequence of the gear is 1. select up-gear doors open and secondary brace unlocks, gear retracts-doors close and secondary brace locks gear up. 2 same process in reverse. Its the exact same system that operates my jet MLG and the NLG on youtube, I just havent put any doors on this current prototype This sequence is much more complicated than a system where the doors close on retraction and stay open on extension. Because of this a traditional four way valve in tandem with the sequence valve is required. Lego dont make a 4 way valve, so I used 4 valves linked together to replicate one. The fifth valve is the retract actuator valve. They are all connected for a single up or down position selection. The combined valve is big, but it works and can be hidden in the airframe. I wanted to make this video to show the operation of the secondary locking brace as this is how pretty much all aircraft landing gears work. without it the gear is relying on a pneumatic or linear actuator alone. Some small aircraft do this, but not larger ones. The principle of overcentre locks like this one are everywhere in aircraft (such as door locking mechanisms, latches etc) Nice to hear from you as always. I think its a shame more people arent working on this large technic aircraft theme as there is so much more to be done! -
New technic main landing gear design
Andy G posted a topic in LEGO Technic, Mindstorms, Model Team and Scale Modeling
Hey folks, Ive been testing a new main landing gear design for an aircraft Im building. Its a variation of my previous desings but I think its kinda neat. Check it out -
new variable pitch propeller design
Andy G replied to Andy G's topic in LEGO Technic, Mindstorms, Model Team and Scale Modeling
Here is a close up photo Thanks for that, ah the model has a 15cm diameter fuselage so yeah its quite a monster. Just taking a long time to develop due to its size. This propeller design has been holding up the wing development so hopefully things can speed up a bit now