My Recent Scale Heli Project...

[Super-Hornet]

Test hover MT with 4 bladed head with BeastX or Microbeast in living room today.
This hover is to test:
1. The feel and behavior of Microbeast on multibladed head. Recently bought Microbeast and this is the 1st time hovering it with this device.
2. Finding the preference RPM required.
3. Testing the Hitec HS-A5076 for tail control.

Result:
So far so good. Microbeast can handle multibladed and to my flying characteristics..but I only test hover in living room so not sure how it perform in forward flight.

Due to Microbeast P.C. software haven't release yet, that mean there is no way to implement phase offset. Therefore, to use it in this heli and to have close to straight linkages on the rotor head, I need to do phase offset by switching around the channel going to the cyclic servo.

In eCCPM120 degree, in MT configuration, the swash plate connection to cycli servos are arrange in 2oclock, 6oclock and 10oclock position. So, I connect Ch1 of Microbeast to right/2oclock servo, Ch2 to center/6oclock servo and Ch3 to left/10oclock. Instead. But by doing so, I need to reverse the direction of the right servo instead. To do this, I program the Hitec HS5065 servo directly using Hitec HPP21. In MB point of view, it is like normal servo but it rotate CCW direction instead. That is the good thing I prefer Hitec digital servo over normal "unbranded" digital servo.

This hover test also verify that HS-A5076 actually can be use for tail servo. The tail hold pretty good.

One thing I a concern is that, the Scorpion HKS2221-1630KV motor is hot. It may not able to handle the load well..especially when include with fuselage. Thus, i might need to replace the motor also.

SH

[JYZoom]

cool....

what blade are you using ? May be shorter blade and your motor will still be good.

Jonathan

[Adrianli]

cool....

what blade are you using ? May be shorter blade and your motor will still be good.

Jonathan

He need more lift for his heavy fuselage. I suggest go with a 500size motor with an adapter mounting plate for 450size motor.

And why the MB is mounted on top of the servo???

[Super-Hornet]

....what blade are you using ? May be shorter blade and your motor will still be good.

The blades is just a normal Align white plastic blades (but painted black). It is just for testing.
I have 360mm blades (2pairs) that is going to be use for this scale...but I cannot use it in this "barebone" test because tail boom too short that the 360mm blades will hit tail blades. But when in fuselage, it is just nice.

..And why the MB is mounted on top of the servo???

That is because I want it be as close as possible to the center of the axis. Just a personal preference.

SH

[Adrianli]

That is because I want it be as close as possible to the center of the axis. Just a personal preference.

SH

Then mount it directly under the main gear upside down lah. Confirm centre of the axis if ur CG is zhun zhun.

[JYZoom]

Then mount it directly under the main gear upside down lah. Confirm centre of the axis if ur CG is zhun zhun.

Good location.....

[Super-Hornet]

I just do some weight measurement on my Pave Hawk.
Fuselage itself is around 810grams!
MT without battery = 860grams!

Adding 1 pairs of 3S1P of 2250mAH battery, it exceed the measurable value my weighting scale can read/handle.

I haven't count in tail blades and main blades weight yet. Overall, the whole thing I believe could be around 2.4kg!!

Looks like I have no choice but to replace the motor to use 500 size motor instead

SH

[Super-Hornet]

Got my 500 size motor today. It is Scorpion HK3026-1400KV.
The MT's motor mounting bracket already have screw holes for 500 size motor actually. Thus, no need to modify the motor bracket.

Bummer part is that, 500 size motor is 4.98 mm (according to the website). There is no pinion for MT's main gear type that is 5mm shaft....that that within 15Teeth count. (Not that I know of)

Therefore, I need to grind down the main shaft to 3.17mm (or close to it) in order to use MT/TRex450 pinion.

Since the motor shaft is 4.98mm or should be compatible to TRex450 main shaft, so instead of grinding down the motor shaft, I cut and grind down TRex450Pro main shaft instead. Why use TRex450Pro main shaft is because it has a "ring" like shape at the middle of the shaft. Scorpion motor is using "C Clip" to hold the shaft into place, So, the TRex450Pro main shaft "Ring" should be able to replace the usage of the "C Clip".

Just completed the grinding. It is tedious because it required a lot of time, drill to hold the shaft and spin at the same time and a dremel to grind it down. The spinning of the main shaft by drill will help to reduce the diameter equally (Think of it like a poor man's lath machine )

I haven't put the new shaft into motor and see how but will do it when have time.

SH

[Super-Hornet]

Even using 16Teeth pinion, the motor is very very close to the antirotation bracket. I tried to grind/dremel down the antirotation braket it order to have some space in between...but the top part of the motor still touches the antirotation. As u can see in the photo, the top corner part of the motor get grind by the antirotation.

I should have chosen a lower KV motor instead because when using lower KV, I can use pinion of teeth more than 17teeth and thus, should have some gap allowance between motor and antirotation braket.

Test spin up and notice the it has very high pitch type. Maybe the pinion not good or the teeth count not suitable.

Decided to drop to 15Teeth pinion instead
I modify the antirotation to mount at the rear instead. With that, I can now drop the pinion teeth count to 15Teeth.

Adjust ESC to spin at 1900RPM (governor). Two piece of 3S1P 2350mAH to form 6S power supply. Place a 4S1P 3700mAH just for the weight purpose. The whole test heli weight at 1848grams!

Test hover in living and to my surprise! It can take off and hover pretty well. The tail however, can hear that it is in higher pitch (2 bladed tail).

EDIT: Oh.. using 15Teeth pinion (from MT), it do not have the high pitch noise compare to the 16Teeth! Sound is much like normal

SH

[Super-Hornet]

Put MT into the fuselage (half fuselage only) for testing the tail drive. Ground spin test (without main rotor) for 1900RPM and with 2 tail blades connected and apply some tail pitch.

After spinning like 1 minutes or so, the "reversal gearbox" fail! It is the tail bevel gear give way. It is like melted away.

The flexible cable looks ok. Hand feel the temperature and the flexible cable at the aluminium as slight warm but the reversal gearbox is warmest of all.

Time repair the reversal gearbox and maybe this time, use the actual tail pulley and maybe apply some translucent grease onto it as well.

[Super-Hornet]

On further diagnose the gearbox, notice some white powdering plastics on MT gearbox (both frontal and the reversal gearbox..except the Tarod tailbox).

Replaced the damage "reversal gearbox" and apply translucent grease on all bevel gears. Same test spin up and so far so good. Gearbox has slightly warm and it is cooler than the aluminium tubing at the rear.

Thus, for those of u who use shaft driven tail, u might want to take note of the gearbox to see any abnormal wear. Maybe apply some lubricant might help.

Anyway, the is the overall mechanical part in the fuselage..part of it. Notice that I use landing skids instead? That is just for temporary. Just an extra support during tuning and assembly.

SH

[Super-Hornet]

Now, putting all together. I lost the original horizontal stabilizer so I have to build one using balsa wood (re-enforce using metal epoxy). Anyway, the original stabilizer is quite heavy and that will set the Center of Gravity WAY OUT. Using balsa wood, it is lighter. Too bad I didn't make the horizontal moveable by elevator stick...maybe next time.

Now it is ready to test fly. I really hope that, with 4 blades of 360mm length, it has the power to lift the heli. Also hope the tail do not fail no me.

SH

[ScorpionM2]

Swee Swee lah bro, hope you post pics or video of it in flight!

[Super-Hornet]

Thanks "ScorpionM2"

Just finish hover test in living room with everything on. Phiew! It can lift off and hover! Tail still holding but i bit of wagging. That should be gain too high. Need to tune it down a little.

Motor wise.. wow! Feels hot. I didn't have my ICE elogger enable and didn't install telemetry on so not sure the ampere drawn and the temperature. Will try to enable elogger and see can put in the telemetry to measure the temperature also.

Let it rest for a while.

SH

[JYZoom]

Very successful moring maiden