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New IRIS by AME

Old 12-01-2022, 07:04 AM
  #241  
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Bigger pulleys allow lowering of belt tension while keeping skipping to a minimum. Could understand the concern with skipping if the pulleys were normal diameter.
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Old 12-01-2022, 07:07 AM
  #242  
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Originally Posted by gigaplex View Post
Seems like the worst of both worlds. Lowering belt tension decreases friction but increases the chances of belt skipping.
I think that chances of belt skipping are reduced by shorter front belt (less flex under tension) and large diameter of the center belt pulleys. But you're right, the friction will be definitely larger than a two belt car.


Originally Posted by gigaplex View Post
Plus the orientation of the belt pushes the motor further away from centreline which is not ideal.
It seems that it doesn't push mush farther than the standard setup. This photo shows shaft of the motor nearly completely inserted in the pinion, so it's almost as close to the baterry as it can be.


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Old 12-01-2022, 08:01 AM
  #243  
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Can roll centers (suspension arm height) be adjusted?
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Old 12-01-2022, 08:10 AM
  #244  
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Originally Posted by Papi View Post
It seems that it doesn't push mush farther than the standard setup. This photo shows shaft of the motor nearly completely inserted in the pinion, so it's almost as close to the baterry as it can be.
This design has the spur closer to the centerline compared to the newer 2-belt designs. From pictures alone (may be wrong), it seems that both the servo and the motor are at least 1-2mm more outwards in comparision to a800, mtc2, x4, etc.
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Old 12-01-2022, 02:39 PM
  #245  
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Originally Posted by rccartips View Post
Can roll centers (suspension arm height) be adjusted?
If you scroll up to post 229 on the last picture, you can see that the little plastic attachments. they are probably where you adjust the roll centers.
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Old 12-01-2022, 03:06 PM
  #246  
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the plastic pieces is to "key" the torsion bar into the damper piston, and the chassis attachment on the last picture of post 229, has zero to do with roll centres.
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Old 12-01-2022, 03:11 PM
  #247  
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Originally Posted by gigaplex View Post
Seems like the worst of both worlds. Lowering belt tension decreases friction but increases the chances of belt skipping. This 3 belt setup will still have more friction even with the loose belts, and still have increased chances of belt skips. Plus the orientation of the belt pushes the motor further away from centreline which is not ideal.
My theory thinks of it this way ....
Bigger pulley for 3rd belt gives more contact on the belt. Increased teeth engagement less chance to skip with a looser tension.
Spool and Diff belts inline with chassis center means less torsional flex effect to belt alignment. Allows for less belt tension to prevent skipping.

Only Con is the power loss in the extra rotating parts. Dont know how to explain that in 'engineering' terms. Something to do with the energy needed to spin them minus the usable energy output of the driving component (aka motor).
Kind of why a shaft drive car can plant more power to the drive train compared to belts.

Battery and motor farther away form center though could help with weight transfer.
As long as they dont overhang and make contact with the race surface then you can tune for the weight shift.

I think theres a lot of benefits in the logic behind the cars design. Possibly too many people focused on whats considered the 'normal' these days for cars.
Many questioned AMX when they came with their ideas, but now we know they work.
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Old 12-01-2022, 04:03 PM
  #248  
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take a look at stadler's 3rd belt "tension" lol


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Old 12-01-2022, 04:30 PM
  #249  
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Originally Posted by Robbob View Post
My theory thinks of it this way ....
Bigger pulley for 3rd belt gives more contact on the belt. Increased teeth engagement less chance to skip with a looser tension.
Spool and Diff belts inline with chassis center means less torsional flex effect to belt alignment. Allows for less belt tension to prevent skipping.

Only Con is the power loss in the extra rotating parts. Dont know how to explain that in 'engineering' terms. Something to do with the energy needed to spin them minus the usable energy output of the driving component (aka motor).
Kind of why a shaft drive car can plant more power to the drive train compared to belts.

Battery and motor farther away form center though could help with weight transfer.
As long as they dont overhang and make contact with the race surface then you can tune for the weight shift.

I think theres a lot of benefits in the logic behind the cars design. Possibly too many people focused on whats considered the 'normal' these days for cars.
Many questioned AMX when they came with their ideas, but now we know they work.
The engineering term is called friction.

There's no benefit to having the battery/motor mass hanging further out. That increases the polar moment of inertia, slowing down rotation.

There's some potential benefit with the suspension design, but the drivetrain doesn't appear to have any benefits. It'll be heavier and have more frictional losses.
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Old 12-01-2022, 04:43 PM
  #250  
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2 big additional pulleys may add a gyroscope effect that would resist rotation.
Wouldn't shorter (less belt wrap) front and rear belts make it more susceptible to slippage vs a longer belt?
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Old 12-01-2022, 04:52 PM
  #251  
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Originally Posted by rccartips View Post
2 big additional pulleys may add a gyroscope effect that would resist rotation.
Wouldn't shorter (less belt wrap) front and rear belts make it more susceptible to slippage vs a longer belt?
Longer belts tend to slip more. The difference in belt wrap isn't that big, but the amount of additional slack from the extra length (the belts do stretch slightly) will make the untaught side much looser.
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Old 12-01-2022, 06:50 PM
  #252  
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Originally Posted by gigaplex View Post
The engineering term is called friction.

There's no benefit to having the battery/motor mass hanging further out. That increases the polar moment of inertia, slowing down rotation.

There's some potential benefit with the suspension design, but the drivetrain doesn't appear to have any benefits. It'll be heavier and have more frictional losses.
I think that he might have been thinking of "rotational inertia."
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Old 12-01-2022, 06:58 PM
  #253  
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I am also interested in seeing how the roll centers can be adjusted. Very interesting car that I think will work well in mod.
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Old 12-01-2022, 07:09 PM
  #254  
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Originally Posted by DBM View Post
I think that he might have been thinking of "rotational inertia."
There is that too but it's so negligible compared to the rotational inertia of the tyres. And it'll only affect the acceleration phase, it won't affect top speed. Friction is the main concern.
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Old 12-01-2022, 07:14 PM
  #255  
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Originally Posted by gigaplex View Post
There is that too but it's so negligible compared to the rotational inertia of the tyres. And it'll only affect the acceleration phase, it won't affect top speed. Friction is the main concern.
I agree completely. Those pulleys are super light. But I think that rotational inertia is what the other person was thinking of.
Hopefully the manual gets uploaded soon. I'm quite curious to see how the lower arms attach, how long they are front inner to outer pivot and how easy/difficult it will be to make roll center adjustments.
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