Thursday, December 10, 2009

My second scale fuselage (MD500E Huges)

I saw someone selling off a 250-sized MD500E fuselage on for an attractive price and decided to buy it.
The photo below is the completed assembly.


I am using a Trex250 sized rc helicopter to fit into this fuselage. It's a bit of a challenge in the following areas:

1) Rudder servo size - First of all, I have to use a smaller servo for rudder. Prior to that, I was using a Align 502 digital servo for rudder but the size of this servo is too big and it would obstruct the boom insertion into the fuselage. In the end, I used an Align 402 servo which is smaller.

2) Rudder servo position - The next challenge is that I need to move the tail servo all the way back until it is literally touching the end of the boom clamp. This was required in order for the boom to complete extend itself out of the fuselage. Also, I had to find a new position for the servo to a somewhat awkward position (and yet functional)that the rudder controls are not affected.


3) Position of Electronic Speed Controller (ESC) and Receiver - As the helicopter is mounted onto the fuselage skeleton interior, the only available space to mount the ESC and the receiver will be at the side of the heli frame. (Remember, this is a 250 size frame, so the esc and receiver is most unlikely to fit inside the frame).

4) Securing tail boom inside fuselage - I also found out that there is a need to 'secure' the boom once it is inserted through the fuselage. By 'secured', I meant a way to prevent the boom from moving about (due to vibration) inside the fuselage as this would affect rudder and gyro readout a great deal. To overcome this, I simply cut a piece of thick sponge to slightly larger than the fuselage boom dimension. Then I cut a hold for the boom to be inserted through the sponge and pushed the sponge into the fuselage. (Like a ring thru a finger). This way, the sponge will absorb the vibration while keeping the heli boom in place! :-)


5) Tail Heavy - Like the other fuselage I assembled (with the 450 sized heli), the final assembly tends to be tail heavy. Even this assembly was no different. I need to put additional weight, up to 45grams of weight pieces in the front in order to balance the heli perfectly.


Well, I must say that I am damn proud of this fuselage. The final looks of it was really satisfying! It flies ok but due to the additional weight, the overall flight time had to be reduced down to abt 3.5 - 4 mins (previously abt 5.5 mins). The good side of it is that I can now use a larger size 1000mah lipo instead of the previous 800mah batt. This is due to the additional space available in the front of the fuselage. (The MD500 has a big 'head'! :))

Hope you like this and find it informative!

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