The flying monkeys got me...

Helis and fixed wing

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Tuesday, December 21, 2010

EXI 450 Project: Well... all done but the hanging of crepe...

I finished the 450 build early this evening. Then I took it apart and started over...

I didn't like the pain in the butt position of the receiver. It works well for an experienced builder/pilot. but for me, who expects to change out a few servos before all's said and done, and who will make significant trims in the programming, it was such a pain to access the plugs and nearly impossible to get the bind plug in to rebind.  So I pulled the receiver, and after looking online for alternative positions, decided to put it under the tail servo. The aileron and pitch servo leads barely made it back there. It looks good, is pretty clean, certainly ain't going anywhere and the middle of the heli isn't threatening to end up in the main gear.

Here's a "prototype" photo!  It lacks the grommets as I learned how to shear them in half with fishing line not quite getting how to use it to get the grommets on. I think I have that figured out. And I want to replace one of the ball links that I took from a Blade 400 kit  to allow me to set up the CCPM mixing (its too small by a smidge).

The hardest part of this build, which isn't really over until I fine tune it and hover it for the first time, was the CCPM mixing. It shouldn't have been... but my flybar cage has been sticky since I opened the box. I rebuilt the bearings etc, and it was still sticky. I redid it today as one of my complete start overs (the other being the receiver mod), and its much better. Under spin it won't be a problem. It was frustrating watching Bob's CCPM part 2 and seeing his bubble stay centered, and his flybar not move a hair, while mine tilted with swash movement (better now).   I do think I have the swash set up pretty darn clean though, and am proud of that. I think there is some fine tuning that will need to be done. Right now I have it set up -8 to +8 for pitch in Idle Up. Its -2 to +8 or so in Normal mode.

There as still some things I am still not too sure about. I am not sure the tail setup is spot on.  I have it centered well, but I couldn't figure out how to set the end limits of travel with the gyro, my MKS GY292. Its not one of Bob's gyro vids. So I did the best I could.  I did the tail mod changing to following edge control, and that seems to look good, but we'll see. The DSP75 servos make a lot of noise just sitting there. Its not a buried servo sort of sound, just a hi-pitched buzz, like it jogging in place just waiting to take off. Nothing is moving, and it sounds solid when the servos get input. Its just noisier than I expected.  I'm using metal gear EXI servos on my 250.  I wish I had more confidence in my build, but I know I barely knew what I was doing.

The proof of the heli is in the hover. If I had a good heli builder around here that I knew, I would really like to have them look it over before I fly it, but I am all alone, with you vicarious minions, whose hopes alone I bring with me for that first spin up!  for now, I am scared to plug in the motor leads!

Thanks for your help!  Stay tuned for maiden flight pics/video. I hope it does not end with the hanging of black crepe...

After the new Year I should have my Dynam E-Razor 450 flight ready, and then I will start on my CopterX 250 build.

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