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    Week 11 | Final Proposal – “Scout”


    2010 - 04.08

    Scout

    For my final mechanisms project I would like to build a twin tilt-rotor remote controlled helicopter.  I am calling it “Scout”.  I found that most types of remote control helicopters are very hard to fly for beginners.  Current R/C helicopter design come in two style coaxial rotors and single rotor with a tail rotor.  The coaxial rotors offer very stable flight but are not agile.  The single main rotor design offers great maneuverability but are hard to fly for novice users.  I want to create a hovering aircraft that is easy to fly and very nimble.  I also want the helicopter able to carry loads such as cameras and small payloads.

    I will be building Scout out of LEGO Technic building blocks.  I choose to build Scout out of LEGO bricks for several reasons.  First, LEGO bricks are a great prototyping platform.  I can build and rebuild my ideas very easily.  The cost of materials is cut because I can reuse LEGO bricks.  If I were to use a material such as aluminum once I cut a piece thats it I cannot go back.    Second, LEGO bricks are accessible to everyone.  I want people able to build Scout on there own with minimal amount of tools.  Third, going back to my first point, LEGO bricks offer modularity.  If I decide later that I want to add another battery bay or a camera arm to the helicopter, I can easily snap those parts into the main design.

    I will be using two electric ducted fans (EDF) for the propulsion.  The frame will be made out of LEGO Technic.  I am using several kits to build the helicopter.  I need to use several kits because one kit doesn’t include all the parts I need to build this helicopter.

    Here are the LEGO Technic  kits that I will be using:

    • LEGO 8297 Off Roader
    • Qty. 2 – LEGO 8265 Front Loader
    • LEGO 8258 Crane Truck

    I also acquired various parts such as gears and shocks off of eBay.  The helicopter is essentially two helicopters in one, hence I will need two of everything.  Each EDF will need an electronic speed controller (ESC), and battery.  I will also need a decent radio system.  I choose the Futaba 7C 7-Channel 2.4GHz Heli with 4 S3152 servos.  I choose the 7C because I need to do servo mixing.  Servo mixing is when two or more servo move together with only one joystick movement.  Cheaper radio cannot do this function.   The motors I will be using are 3600kv Outrunner Brushless Motors.  I will be using two 45A Brushless ESC.  The batteries to power Scout are lithium-ion polymer (LiPo) batteries.  I chose two 11.1 volt 2800mAh 30C batteries.

    Scout isn’t cheap but compared to current helicopter in it’s class it is a bargain.  I sourcing the EDF and batteries directly from Hong Kong, China.  I saving over $300 ordering directly from China.  All the electronics parts are made in China.  The US stores order their parts from China.  I am cutting out the middle man by ordering directly from China.  The downsides of ordering from China instead of order from the US is the shipping duration is weeks instead of days.  The other issue is the build quality of parts can be can be hit or miss.  You may order two batteries, one battery may operate perfectly while the other is DOA.  Chinese seller will replace your defective battery but you will have to send them the defective battery and they will not reimburse you for the return shipping cost.  Even with the risk of a DOA parts, it is still cheaper to order directly from China.  Price list of Scout are below.

    Price list:

    • LEGO 8297 Off Roader….$130
    • LEGO 8265 Front Loader….$80  x2
    • LEGO 8258 Crane Truck….$250
    • EDF with Motor and ESC….$48 x2
    • Futaba 7C heli with servos Radio System….$350
    • 11.1v 2800mAh 30C LiPo Battery….$25 x2

    Grand Total $1036

    Schedule:

    March 15 – April 10….Order supplies

    March 20 – April 16….Begin Construction

    April 17 – 20………….Begin testing and setting up the radio

    April 21 – 27………….Test flight and revise

    April 29……………….Present

    Here is my concept design for Scout.  I used Omnigraffle to create the concept design.  I measured the parts and input them into Omnigraffle to get an accurate scale of my design.

    Scout Diagram

    First Prototype of Scout

    Scout Proposal PDF

    The PDF proposal also includes a part list with the weights of each part.  I also calculated the total power to weight ratio of Scout.

    Week 10 – Free Body Diagram | Car Jack


    2010 - 04.01

    This is a free body diagram of a car jack. This free body diagram indicate some of the force that are acting on this car jack when in use.  Fn is the normal force pushing up from the floor.  Fg is gravity pushing down on the car jack. Ft is the torque force being applied by the user.  Fl is the lifting force being generated by Force torque.

    Week 6 – Midterm | Steam Powered Generator


    2010 - 03.23

    For my midterm project in Mechanisms I created a electric generator powered by steam.  For safety concerns with NYU I am using compressed air to power the electric generator.  Currently, this project isn’t finished.  Air leaks out of the top of the tapped pipe.  I tried to patch the leaks with plumbers putty, but air is still escaping.  Also, I need to add a safety valve before I begin to power it by steam.

    Week 5 – Midterm Project Proposal


    2010 - 02.27

    Mechanisms Midterm Project Proposal

    February. 25, 2010

    For my midterm project I would like to make a electric generator using steam. The components that I will need are a heat source, boiler, piping, turbine, electric generator,  and a electrical output.

    The heat source will a propane torch.  This can be purchased at Home Depot for about $45 with propane tank.  I will also use the torch to solder the piping together.  The boiler will either be a found item that can suit the requirements of a boiler or I will make a boiler out of copper piping and caps.   I will need a 2 inch copper pipe with 2 inch copper caps.  The total cost for these parts is $24.  For the turbine I plan to convert an air grinder into a turbine motor.  I am hoping the boiler can build enough pressure to power the air grinder.  The air grinder will cost nothing because I have an air grinder that I can convert.  I plan on using an electric motor for the generator.  I have plenty of motors to choose from and will have to see which one will work best.  I will need a linkage from the air grinder to the electric motor.  I plan on using spare parts that I have to create the linkage.  I then use a light to show the energy being create by the generator.  The total cost for this project will be around $90 half of this is for the propane torch.  I also allowing $21 for fittings and scrap metal.

    Schedule:

    February 25 – March 1…. Order supplies

    March 2 – 4……………….Construct Boiler

    March 5 – 6……………….Pressure test boiler and adjust if needed and construct turbine and motor linkage

    March 7.….……………….Attach Turbine (Air Grinder) to boiler, assemble and attach linkage to turbine and motor

    March 8…………………..Troubleshoot any problems

    March 9…………………..Troubleshooting

    March 10………………….Mount and fix components to base, connect output light

    March 11………………….Present