MD500 Tow Defender Build Page 11
Flybarless Electronics and Two to Five Blade Rotor Head Setup:
For this project I am going to try the lastest craze used around my flying field, the MicroBeast flybarless controller. I also get at the field and LHS support with this one which does help from time to time. Although I am the only guy in my club doing multi bladed heads, so support for that is none. Anyway, for the first phase of the FBL setup I will be using a two blade head. I figured I might as well simplify where I can. After I get a good feel for the two blade head I will move onto the five. Once I decide to move to the five blade head I will also need to swap out the original 1220Kv motor with the 670Kv, remove the Align ESC and connect the Castle ESC, and stop using the 6S lipo and connect my home made 10S A123 pack. So you can see that the switch to the five blade head involves a bit more work the the two blade.
With the two blade setup I will run the heli just as it came. When I switch to the five blade I will need to make a test bed setup as I will have no where on the original mechanics to put the 10S battery pack. I alos have to cut the side frames to fit the X-era motor in. It's just a bit larger than the stock one. I saw a guy on HeliFreak do the same thing and he added some custom made aluminum brackets to replace the material he cut away. I plan to do the same thing.
As stated above, here is the two bladed head installed and ready for blades. Thank you Mike B. for letting me use
this Outrage head. This way I didn't have to go buy something that would end up sitting around after a few flight tests.
Just another photo of the head with blades mounted.
Here I have masked off the area where I will cut out the side frames to make room for the larger motor.
I just used a cutoff disc on a dremel tool and it worked great. Quick and clean. I did put the shop vac undereneath
to suck the fibers and dust away.
Here you can see the side frame cut out. I still need to make the stiffeners
to span one side of the motro to the other.
Original motor next to new motor. Only a few millimeters difference, but that all it takes.
The new motor also has a built in fan which I hope will help keep it cool.
Here is the clip-board test bed. The CC ESC has been mounted using it's mounting tabs.
The two A123 packs will be secured with tie wraps and foam. The flight pack with rubber and tie wraps.
The main motor batteries are wired in series to form the 10S pack. You will see later how they are mounted.
Main motor packs are mounted and ready to go.
Here it is ready for it's maiden flight test. It aint pretty, but it will fly.
So, I have put 6 - 8 flights on the above setup and it is working great. It flies very smooth accross the sky. I did not notice any porposing or other strange flight
characteristics. It would just fly great. I did not try any real hard banked turns, rolls, or any other stunts with it. Just what I thought would be correct for the scale heli it is.
I did end up putting larger tail rotor blades on after installing the mechanices back into the fuselage. I went from stock Trex600ESP blades (about 94mm) to some
larger 115mm blades. This corrected the problem of just as it would lift off it would rotate hard to the left.
One problem I had was trying to get the blade tracking to be perfect. I just figured out part of the problem the other night while moving it around my shop. Two of the
five blades have sloppy blade grips that allow the blade to move up and down about 1/4 inch at the tip. A third blade moves about 1/16 inch or so the same way. I have
now replaced the two worst blade grips and await a test flight to see how it works. Hopefully this should reduce some vibs overall. I don't have a third spare blade grip,
so for now I will just have to see what the two do for it.
The next thing I really need to address is the motor power. I did not know the A123 batteries would drop so much voltage under the 25 - 30 amp load the motor is pulling.
I may end up removing them and going to Lipos along the frames. Probably two 5S packs in series. I am hoping to learn more while down at the Kansas City, MO. first scale
fun fly. I hope to meet with the more experenced scale builders and learn from them.