Schumacher Corner
04-13-2004, 02:18 PM
#5822
Olev - It is true that the less the belt bends the more efficient it is but the primary benefit is the lower belt speed.
The car with the lower internal drive ratio's belt has to rotate less to turn the wheels the same amount. There are 2 main benefits of this:
1. Lower belt speeds reduce frictional losses from tooth engagement.
2. Lower belt speeds let the car go faster before the onset of negative belt harmonics (out of control Belt flapping). This was never an issue in Schumacher as we have always been aware of this problem and have always taken measure to eliminate the problem from our cars. However Corally C4.1's, Tamiya 414X and Early Xrays all had huge problem with this when running Mod motors on big tracks. Interestingly enought...shaft are are not immune to this. Negative shaft harmonics are why no one runs carbon shafts on their TC3's anymore.
FYI, Sedan design is serious business. They are not sketched out at bars on cocktail napkins (thats how Mountain Bikes are designed...lol!). Schu UK has former IFMAR WC Phil Booth as the head of R&D, Engineers and CAD/CAM/CNC experts and racers with a combined racing experience of 40 years in the US office alone. Cecil Schumacher was a transmission engineer for an F1 team for 20 years before he got into R/C.
We also have specialized engineers that consult on certain projects. Like the Gates Belt engineers that consulted on the Mission, R12 and Fusion 21 drive trains.
The car with the lower internal drive ratio's belt has to rotate less to turn the wheels the same amount. There are 2 main benefits of this:
1. Lower belt speeds reduce frictional losses from tooth engagement.
2. Lower belt speeds let the car go faster before the onset of negative belt harmonics (out of control Belt flapping). This was never an issue in Schumacher as we have always been aware of this problem and have always taken measure to eliminate the problem from our cars. However Corally C4.1's, Tamiya 414X and Early Xrays all had huge problem with this when running Mod motors on big tracks. Interestingly enought...shaft are are not immune to this. Negative shaft harmonics are why no one runs carbon shafts on their TC3's anymore.
FYI, Sedan design is serious business. They are not sketched out at bars on cocktail napkins (thats how Mountain Bikes are designed...lol!). Schu UK has former IFMAR WC Phil Booth as the head of R&D, Engineers and CAD/CAM/CNC experts and racers with a combined racing experience of 40 years in the US office alone. Cecil Schumacher was a transmission engineer for an F1 team for 20 years before he got into R/C.
We also have specialized engineers that consult on certain projects. Like the Gates Belt engineers that consulted on the Mission, R12 and Fusion 21 drive trains.
04-13-2004, 04:45 PM
#5824
Adrian, can you take a moment to explain why the belt speed differs depending on the pulley size?
Surely for any given car speed, the belt speed over the diff pulleys (and therefore overall belt speed/revolutions) must be identical. I would have thought the only way to truly vary belt speed would be to change diff pulley size.
As Olev mentioned, it woudl be the layshaft pulley speed that would vary - turning faster with the smaller pulley and slower with the larger pulley.
I would think there could be an effect of "accelerating" the mass of the belt from a standstill or slow speed, but ultimately for any given car speed, the belt speed must be the same either way.
I'm quite open to you pointing out how wrong this understanding is - I'm certainly no mechanical engineer.
Surely for any given car speed, the belt speed over the diff pulleys (and therefore overall belt speed/revolutions) must be identical. I would have thought the only way to truly vary belt speed would be to change diff pulley size.
As Olev mentioned, it woudl be the layshaft pulley speed that would vary - turning faster with the smaller pulley and slower with the larger pulley.
I would think there could be an effect of "accelerating" the mass of the belt from a standstill or slow speed, but ultimately for any given car speed, the belt speed must be the same either way.
I'm quite open to you pointing out how wrong this understanding is - I'm certainly no mechanical engineer.
04-13-2004, 05:43 PM
#5826
well, if I remember correctly, silvers equal 12.5 or 15 lbs and blues equal like 15 or 17
soo....
soo....
04-13-2004, 06:23 PM
#5827
Tech Initiate
Blue average rating16.5-on package rating17lbs
Silver average rating13.8-on package rating14.5lbs
Silver average rating13.8-on package rating14.5lbs
04-13-2004, 07:17 PM
#5828
Besercoe..congrats on your choice of sedan!..
strange issue you mentioned with on power aggressivness, If anything, I have found the Mi2 to be very sedate to drive...like a broader limit..whereas the Mission always felt nervous...the Mi2 feels very controlled..
check over your droop settings, make sure your shock lengths are ok (could be a concern using foams)..for rubber/ashpalt I use 64.5 front length, and 65.8 rear length...this allows maximum uptravel, and adequate extension...
some people are using tamiya shocks as they provide further travel / droop.
Schumacher is in the process of designing all new shocks...(this is why team drivers were spotted using other brands of shocks in testing) (they will be mint)..
fire me a message if you have any q's..
strange issue you mentioned with on power aggressivness, If anything, I have found the Mi2 to be very sedate to drive...like a broader limit..whereas the Mission always felt nervous...the Mi2 feels very controlled..
check over your droop settings, make sure your shock lengths are ok (could be a concern using foams)..for rubber/ashpalt I use 64.5 front length, and 65.8 rear length...this allows maximum uptravel, and adequate extension...
some people are using tamiya shocks as they provide further travel / droop.
Schumacher is in the process of designing all new shocks...(this is why team drivers were spotted using other brands of shocks in testing) (they will be mint)..
fire me a message if you have any q's..
04-13-2004, 07:23 PM
#5830
I just built a Mi2 the other day and although it all went smoothly and the car looks great, the drivetrain concerned me. It looked like the main belt was getting severely pinched at the rear diff between the edge of the diff and that spacer ring that is on there. Is that a big concern, or is it something that will work its way in after running a bit? I'm fairly certain I didn't do anything wrong building it... 
04-13-2004, 08:26 PM
#5834
STLNLST ...email me at [email protected] I never check the rcracing.com email anymore (to many "you to can be a real man" emails 
) ...cars built up to the mounting the shocks so would love to get a hold of the missing piece!!
) ...cars built up to the mounting the shocks so would love to get a hold of the missing piece!!