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New technic main landing gear design

aircraft main landing gear

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#1 Andy G

Andy G

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Posted 07 November 2012 - 12:37 PM

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


#2 Tadej


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Posted 07 November 2012 - 02:08 PM

Very nice, the aircraft that would use this landing gear would have to be huge.

#3 Carsten Svendsen

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Posted 07 November 2012 - 02:59 PM

I don't understand what the little cylinder does, but I assume it's connected to the squence valve and controls the locking brace. If so, couldn't this be done mechanically on the right side of the boom instead of using a cylinder on the outside? This also reminds me that I have to make a proper sequence valve placement, because where it's located now, it causes too much stress on the landing gear cylinder (too hard to switch), and sometimes it'll come off.
What are you planning to attach to you 5-step valve system? For this, I assume you would only need 1valve.
I can also see you don't like to make proper hose connection. Those you have made are probably only temporarily, but in any regard, they'll very easily pop off with little pressure.
My current project: Antonov AN-140 which is a 1:15,65 scaled airplane

#4 Andy G

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Posted 08 November 2012 - 11:29 AM

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!

#5 Jeroen Ottens

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Posted 08 November 2012 - 06:35 PM

Cool mechanism.
But as Tadej said, the aircraft must be quite big to accomodate such a large landing gear... What are you planning to build?

You're not the only one building big aircrafts though :) Wait for the upcoming Hispabricks magazine for the premiere of my latest technic aircraft (90 cm long :)

Keep up the good work. In my experience with building planes the landing gears & bay doors are the most challenging parts of the plane, so getting that to work is half the job :)

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