XB-E Spec confirmation for input into a Est Speed Calc

[Gee]

Could someone help verify these specs for me. BrianG at RCMonster.com has an cool web page with a bunch of useful info for brushless setup. One is the estimated speed calc.


R/C Calculations Link:


http://scriptasylum.com/rc_speed/index.html


Speed Calc Link:


http://scriptasylum.com/rc_speed/top_speed.html


Specs I gathered from the online XB-E manual but need verified:


Differentials


33t Ring Gear


11t pinion


(33/11) Diff Gear Ratio: 3


Spur & Pinion Gear (Manual has two pinions listed)


41t Spur Gear


10t Pinion


11t Pinion


LIPO Batteries & Voltage


(2) 11.1v 3s 3600mAh lipos


22.2v Total 6s Lipo Setup


Motor KV? XB-E listed two but I foung a seperate document for the motor B4485.


960kv Brushless Motor Specs seperate Documentation


1150kv XB-E Manual


1220kv XB-E Manual


Tire Diameter?


XB-E Buggy tire: 6"


PLine Excavator: 7"


I couldn't find a size anywhere for the buggy tires. I plugged the Proline Excavators size into the calc.


This is the output I got by plugging in the numbers bolded from above:


Differential Ratio: 3


Transmission Ratio: 1


Other Ratio: 1


Spur Tooth Count: 41


Pinion Tooth Count: 11


Total Voltage: 22.2


Motor KV: 960


Tire Diameter (inches): 7


Tire Ballooning (inches): 0


Motor Current Draw: 0


Motor Coil Resistance: 0


Spur/Pinion Ratio: 3.73 : 1


Total Ratio: 11.18182 : 1


Tire Circumference (inches): 21.99 inches (558.58 mm)


Rollout: 1.97:1


Total Motor Speed: 21312 RPM


Vehicle Speed: 39.69 mph (63.76 km/h)


Effective KV Value: 960


KT constant: 1.41 oz-in/A


Motor Torque: Amperage not specified...


Final Torque: Amperage not specified...


Final Power: Amperage not specified...

 

[RedcatRacing]

You are a math wizard good sir!


Just uploaded video with some radar speed runs.


I tested this same vehicle before and it was a few MPH faster but I will stick with your math and these latest runs as the stock top speed.


[ame]

[/ame]
Darin

 

[Gee]

Thanks for the video and the comment but BrianG is the real math wizard. Do you know the diameter of the stock tire for hte XB-E? Also, do I have the pinion size right at 11t?

 

[fastlane]

Nice video and 38 on the stock system is pretty darn fast. I can't wait to see what a Mamba XL will do.

 

[Obeast44]

Love the vid Darin!


The tires are 6" in diameter...so by the speed calc at max voltage of the fresh packs (4.2v/cell) top speed should be 38mph, pretty dang close eh? At 3.7 volts/cell top speed drops to around 34mph and around 3.2v/cell (my lipo minimum) top speed drops to around 30mph. The speed calc is definitely worth bookmarking, ive used it for quite some time.


Here is my results at 4.2v/cell with fresh lipo packs off the charger:


Differential Ratio: 3


Transmission Ratio: 1


Other Ratio: 1


Spur Tooth Count: 41


Pinion Tooth Count: 11


Total Voltage: 25.20


Motor KV: 960


Tire Diameter (inches): 6


Tire Ballooning (inches): 0


Motor Current Draw: 0


Motor Coil Resistance: 0


Spur/Pinion Ratio: 3.73 : 1


Total Ratio: 11.18182 : 1


Tire Circumference (inches): 18.85 inches (478.78 mm)


Rollout: 1.69:1


Total Motor Speed: 24192 RPM


Vehicle Speed: 38.62 mph (62.03 km/h)


Effective KV Value: 960


KT constant: 1.41 oz-in/A

 

[Gee]

Thanks Obeast! I added to my first post to show the buggy tire. Good point on the fresh lipo charge. I am pulling the plug and ordering up a XB-E as we speak. The 5b is going up for sale soon! I already ordered some more lipos to go with the pile of 3s lipo I already have. Picked up a couple of 6s 5000mah 30c today.

 

[Obeast44]

Thanks Obeast! I added to my first post to show the buggy tire. Good point on the fresh lipo charge. I am pulling the plug and ordering up a XB-E as we speak. The 5b is going up for sale soon!

Acckk! That means only 29 left!!!!!! Crap I wish the USPS would pay me the damn money they owe me already so I can get one! In all seriousness, grats!