Lego 9398 - Motorized Rescue Helicopter

Nothing new in this, as per building instruction. The length and width is bigger than Unimog & Crawler, mainly due to the main-rotor. Height wise, lower. I did not put on any stickers ... yet.

I don't know about others, but my winch is very tight. Due to the grey-pin bush with friction below. The motor can't turn this, so I replaced with a 5.5 axle with stop. BTW, I use my own longer string. However, when I disengage the gear for winch, it is free fall when something is on the hook.

I may need to sacrifice some spare bush-pin and sand-down some of the friction on the pin. Or research more for other solutions.

I do not have the power-function motor set (8293), so I take the parts from other vehicles to try here:
- M-motor
- Battery box
- IR receiver
- Remote control
- 8-tooth gear
- 24 tooth gear with clutch (white)

All works fine, after the above fix for the winch. Here is the video with the winch, rear-cargo door, landing-wheels and rotor.

Something I note (before I do further research on internet), when the rotor rotates, it has momentum and when I stop the motor, the rotor will continue for a while. This can mean disaster for the gears, as the rotor forces the gear to rotate the motor. Hence, a smart design here for the safety mechanism, there is a gear on L-beam which can roll up to prevent gears grinding. 

Also, this means the motor can only rotate the rotors in one single-direction. If switch the other direction, the gears will rotate freely. Which is what a helicopter rotor should be, rotate in one direction for lift. Below is the video of how it works.

All in all, the helicopter is quite complete. There is a stick to adjust the rotor pitch.
One thing missing though, is the tilt (front and back) for the chopper to move forward/backward, in real life.

Lego Technic - 8110 with XL Motor

I re-use the XL motor for this testing. Again, there are a lot of info on the web.

The XL motor is temporary mounted at the rear chassis. I did not put back all the braces/fittings. The space is just fit for XL motor. You may try with the smaller size L or M motor and it will definitely fit.

Wheels rotate as expected, without gearing down, yet. 

Further testing, for the steering, the XL motor is fitted vertically inside the cab, at the back. I did not change the yellow-knobs into gears yet, as this is just a trial. 
Also, both the motors are connected to the IR for remote control.

The result ? 

Yes, it works. But this is just pre-liminary testing. There are many pros and cons which I will list out below (that I can recall as of now):

1) Major: Need to gear down at all 4x wheels, by getting extra gears for it. Otherwise, it may stress the XL motor driving it.

2) Major: Yellow steering knob not effective for turning. Also, the far position of the motor for steering is not suitable. 

3) Major: 8110 steering design fault. Those who have one (8110), will know the difficulty in twisting the black knob above the cab to steer the front-wheel on the ground if it is not moving. Refer the video below by nicjasno (all credits goes to him)

4) Major: Without servo-motor or other manual-way, the steering does not return to centre, like the 9398 4x4 Crawler.

Therefore, these are the things in my mind for to-do list:
a) Gear down at the wheels. Simple mod.
b) Install the servo motor at bottom (lower chassis). Do not use the cab area.
c) Try to fit 2x XL / L motor to provide individual power for front and rear. I think L motor is feasible, if remove the front 4-pistons engine.
d) Modify the front steering mechanism.

Let's see how it goes along in future. I am ordering extra parts and stuff currently...

Lego Technic 9398 XL Motor modification

Recently bought 2x XL-motor (8882), pictured here on top 8110.

Read & view up some MOC ideas... and started my own modification to change the both the motor from L to XL.
Currently, I don't have enough extra parts, hence I make do with a rough-design, and about 60-70% sturdiness, at least for now. There will be future versions.

Angle-view

The chassis expand 1 beam wider on each left & right side, to accomodate the wider XL motor and free-play for suspension.
Suspension remains at same height, but split wider due to expand chassis.

Back-view

Change the gears and affect the ratio. XL motor is about half the RPM of L motor, but with higher torque, hence not much speed improvement. Crawling over objects is slightly better though.
Extra bracing to hold the motor & gears in place. No gears skipping/grinding.

 

Side-view

Notice the taller XL motor, the height is nearly touching the upper portion of the car. Hence, I may need to modify further to increase the suspension by 1 beam.

That all the own testing I've done so far. I know there are many more complete versions/blog/video out there, but this is at my own pace and testing.