42113 Osprey, Mods and improvements

[Ngoc Nguyen]

So it has been established that there is a problem with the spinning function. The motor struggles to deliver power. I hypothesize that the central reason is that the drivetrain isn't geared down properly. The ratio between the motor's axle and the spinning axle is 1:1. 

The fix now is to force a pair of 12z-20z somewhere. But it's hard because the transmission is so dense with gears and beams. I haven't tried it out, but I think the most feasible place to fix is the brace in the white frame.

The transmission there goes like this: (20/12) x (12/12). I plan to get rid of the 3-side brace somehow to force a gearing down setup there.

Another feasible place is the wing. But I haven't figured out how to gear down linearly

@efferman Can you take a look and give it a try? 

[R0Sch]

I think it's possible to switch the top z20-z12 gears by replacing the black connector piece 87408 with a 32184. The tan bevel gear can be fixed by bushes axially.

Edited July 28, 2020 by R0Sch
correction

[Ngoc Nguyen]

9 minutes ago, R0Sch said:

I think it's possible to switch the top z20-z12 gears by replacing the black connector piece 87408 with a 32184. The tan bevel gear can be fixed by bushes axially.

Yes that might work. I'm also thinking about forcing a pair of 12z-20z half gears into the connection point between the axle from the body and the axle from the rotor.

Oh you know what, I've got a better idea. Swap the 12z-20z so that the 12z is in the bottom, while the 20z is in the top. Then replace the 12z half gear on the yellow axle with a 20z half gear.

Edited July 28, 2020 by Ngoc Nguyen

[pleegwat]

3 hours ago, Ngoc Nguyen said:

Swap the 12z-20z so that the 12z is in the bottom, while the 20z is in the top. Then replace the 12z half gear on the yellow axle with a 20z half gear.

You can't replace the 12z on the yellow axle without moving what is currently a black 12z further from that yellow axle, which requires moving the gear below it as well. It would be easier to move it further away - change 20-12-12 to 12-20-12 (so effectively 5:3 to 1:1). The black brace you can replace with a 3l beam, since you just need that centre hole.

[Ngoc Nguyen]

I think I found out the cause for the intermitten behavior of the spinning blade. It's actually the red connector pinhole + 2 pins in red on both sides.

I stripped down the gearbox back to that stage, and I tried spinning the axle manually. I notice that the intermitten spinning ONLY occurs when the yellow axle is fully inserted. Then it dawned on me that if the red connector only slightly deviated from the parallel position, it will rub into the universal joints and cause intermitten friction.

[anyUser]

4 minutes ago, Ngoc Nguyen said:

Then it dawned on me that if the red connector only slightly deviated from the parallel position,

But wouldn't these be properly aligned when the wings are attached to them, cf. picture from your previous post?

[R0Sch]

15 minutes ago, anyUser said:

But wouldn't these be properly aligned when the wings are attached to them, cf. picture from your previous post?

They would, but the connections have some free-play, the wings are heavy and the universal joints have very little clearance to the red connectors (at least in 3D from what I see). Maybe CV-Joints could be used instead of universal joints. Would have been preferred anyway for constant rotation speed.

[Ngoc Nguyen]

30 minutes ago, anyUser said:

But wouldn't these be properly aligned when the wings are attached to them, cf. picture from your previous post?

Right, I tried to make them aligned and the motor still struggle. It's not because of the red connectors then.

[anyUser]

10 minutes ago, Ngoc Nguyen said:

Right, I tried to make them aligned and the motor still struggle. It's not because of the red connectors then.

You could get slightly better clearance if you replace the red connector by a 3L friction pin that has this instead of the black 2L friction pin.

[Ngoc Nguyen]

7 hours ago, R0Sch said:

I think it's possible to switch the top z20-z12 gears by replacing the black connector piece 87408 with a 32184. The tan bevel gear can be fixed by bushes axially.

 

3 hours ago, pleegwat said:

You can't replace the 12z on the yellow axle without moving what is currently a black 12z further from that yellow axle, which requires moving the gear below it as well. It would be easier to move it further away - change 20-12-12 to 12-20-12 (so effectively 5:3 to 1:1). The black brace you can replace with a 3l beam, since you just need that centre hole.

I'm so sad to report that this mod doesn't work. I've just tried it. Because the 20z is now only connected to only one side of the frame, during high spinning from the motor, it's constantly bobbing around and skipping the meshing with the half 12z on the yellow axle. The result is a much more vibrating and friction-laden transmission.

Don't attempt this at home. It doesn't work.

 

EDIT: The problem is actually else where. The 20z-12z meshing did work when the problem elsewhere is removed. Please disregard the above,

Edited July 28, 2020 by Ngoc Nguyen

[anyUser]

Is the 20tooth gear rotating on an axle or a axle pin?

Have you tried using a blue 20tooth gear on a frictionless pin?

Edited July 28, 2020 by anyUser

[Ngoc Nguyen]

Just now, anyUser said:

Is the 20tooth gear rotating on an axle or a axle pin?

Tan frictionless axle pin

[R0Sch]

How about this idea? The grey part is an L liftarm to offer some suport on the beam below it. The 2 red 3L pins with axle replaced by 2 blue 3L pins.

[pleegwat]

17 minutes ago, Ngoc Nguyen said:

 

I'm so sad to report that this mod doesn't work. I've just tried it. Because the 20z is now only connected to only one side of the frame, during high spinning from the motor, it's constantly bobbing around and skipping the meshing with the half 12z on the yellow axle. The result is a much more vibrating and friction-laden transmission.

Don't attempt this at home. It doesn't work.

 

This also shows any solution with a 20z on the yellow axle would run into problems due to the perpendicular 20z below it.

[Ngoc Nguyen]

@R0Sch @anyUser

I found out the reason. The skipping didn't happen at the big 20z meshing with the half 12z on the yellow axle. It happened somewhere else. The 20z-12z half gear mesh has no problem at all once I fixed the skipping somewhere else.

And the skipping happened

 

 

at the 2 8z gears coming from the red 16z clutch gear. In the original setup in the photo above, the 20z gear is big enough to block the red axle from coming back out from the connector with the switch. But when I swapped the two gears, the 12z gear is in the bottom and can't block it. The red axle protrudes slightly and interferes with the 12z gear, thus causing the skipping.

Edited July 28, 2020 by Ngoc Nguyen

[pleegwat]

That sounds like it would cause friction in the original setup as well.

[R0Sch]

I also read on another thread here that the new z12 and z20 gears have some friction issues due to rough edges (burrs). Could lead to additional strain. Please check the edges and if they rattle in manual mode.

7 minutes ago, Ngoc Nguyen said:

@R0Sch @anyUser

at the 2 8z gears coming from the red 16z clutch gear. In the original setup in the photo above, the 20z gear is big enough to block the red axle from coming back out from the connector with the switch. But when I swapped the two gears, the 12z gear is in the bottom and can't block it. The red axle protrudes slightly and interferes with the 12z gear, thus causing the skipping.

I also noticed this when modeling it in Studio. There is no room for error and axles tend to move over time.

[Ngoc Nguyen]

The mod finally works!!!!!

I combine this

 

 

with this

 

 

What my mod does is basically gearing down the drive train from the motor to the spinning blades. The original gear raio is 1/1, which means very little torque. My mod makes the final gear ratio (12/20)^2, which is 9/25. This will make the blades spin approximately 3 times slower but ensure that the motor doesn't strain itself.

The blades spin much more slowly but the motor is no longer stressed. The rotation speeds of the axle coming from the motor when the spinning blades are turned on and off are the same now. The sound is also the same. The motor is finally at peace.

Edited August 1, 2020 by Ngoc Nguyen

[R0Sch]

Cool, thanks for sharing. Could you also try my mod without the further reduction at the engines? Maybe it's enough to have 1:2.77 reduction instead of 1:4.63

[Ngoc Nguyen]

Just now, R0Sch said:

Cool, thanks for sharing. Could you also try my mod without the further reduction at the engines? Maybe it's enough to have 1:2.77 reduction instead of 1:4.63

I don't think that would work, because before modding the central gearbox, I already mod the 12:20 ratio into the rotors, and turned on the spinning blade. The motor still struggled with 12/20 in both rotors.

[R0Sch]

3 minutes ago, Ngoc Nguyen said:

I don't think that would work, because before modding the central gearbox, I already mod the 12:20 ratio into the rotors, and turned on the spinning blade. The motor still struggled with 12/20 in both rotors. 

Yes, you are right. I miscalculated. The first mod makes the ratio 1.66:1 and both mods 2.77:1. So this will lead to more torque on the output and less on the input meaning no more damaged z8 gear as described by the reviews.

[Ngoc Nguyen]

13 minutes ago, R0Sch said:

Cool, thanks for sharing. Could you also try my mod without the further reduction at the engines? Maybe it's enough to have 1:2.77 reduction instead of 1:4.63

I've just tested that. The motor slightly struggles to start, but the blades spin normally. No sound of straining.

So to recap:

- 20-12-12 in the gearbox + 12-12 in the rotors: Disaster. Motor is straining, struggles to start, and struggles to deliver power. Transmission is visibly intermitten.

- 20-12-12 in the gearbox + 12-20 in the rotors: Disaster. Motor is straining, struggles to start, and struggles to deliver power. Transmission is visibly intermitten.

- 12-20-12 in the gearbox + 12-12 in the rotors: Blades spin slower. The motor slightly struggles to start the function, but the blades spin normally. No sound of straining.

- 12-20-12 in the gearbox + 12-20 in the rotors: Blades spin slowest. The motor starts the function normally. The blades spin normally. No sound of straining.

Conclusion: I recommend the last option. I'll leave my model permanently in the last option as well.

[Bartybum]

Any chance of a video showing how slow the modded setup now is?

[R0Sch]

7 hours ago, Bartybum said:

Any chance of a video showing how slow the modded setup now is?

The blades will spin almost 3 times slower. Just use a YT review video and adjust playback speed.

[lee1980]

Is it a simple case making as per the 2 pictures? are more parts needed to do?