Notices
RC Electric Off-Road Trucks, Buggies, Truggies and more Discuss electric RC off-road, buggies & trucks here. Also discuss brushless motors, speed controllers aka ESC's, brushed motors, etc

Troubling observations about brushless . . .

Old 06-26-2007, 04:10 PM
  #1  
rdbruski
Junior Member
Thread Starter
 
Join Date: Jun 2007
Location: Mesa, AZ
Posts: 8
Likes: 0
Received 0 Likes on 0 Posts
Default Troubling observations about brushless . . .

The power of brushless in a toy sized package is a wonderful thing. While watching videos of brushless trucks, I'll admit, I have a grin on my face the whole time. I plan on converting my T-maxx 3.3 to brushless. However, a little bit of the infatuation is wearing off about brushless and I'm seeing things a different way now.

Virtually ALL the videos I've seen shows the awesome power of a brushless truck with its front wheels off the ground most of the time and many times the truck on its tail or back and out of control. At first, the power monger in me wants to build a powerful monster brushless truck with all that power. On the other hand, I remember how fun my T-maxx 3.3 nitro was when I had it running. The front end rarely came off the ground and all 4 wheels were down, steering and in control. It didn't have the speed or torque the brushless trucks have, but you could actually bash and steer with it which to me is more fun! I've only seen maybe 1-2 video's out of DOZENS where a brushless guy is actually playing with his truck in a way it is actually in control and having fun.

To me, the overpowered brushless trucks do not look fun at all. I plan on playing with my brushless T-maxx with my young son. From what I've seen, he'd not have the dexterity to run a brushless, much less me.

Can you help me understand what I can do to go brushless with my T-maxx but still make it be fun?

From what I've read, there are several factors producing this out-of-control scenario. Tell me if I have this right . . . 1) Over powerful battery/motor combination for the weight of the truck. 2) Poor front end weight dynamics. 3) Incorrect gear ratios. 4) No chassis tilt.

1 - I understand the wheel popping is from the massive torque from brushless motors. Are people just buying over large batteries/motors supplying too much torque?

2 - Wouldn't added front end weight help to keep the nose down? How about mounting the batteries in the front? I have an RC Solutions roll cage, so battery damage won't be an issue for me.

3 - I know gearing can have an impact. Wouldn't you want a gearing strategy to produce less low end torque to keep the front on the ground?


4- On my T-maxx 3.3, I bought some really nice Nova RC shock towers and the Big Bore shocks. I mounted the shocks in the back so that the back was considerably higher. Then, when I'd take off, the back end would squat down as normal, but instead of lifting the front end, it now would run level. Is this a good strategy for brushless power also?

Wouldn't these changes be better on the drivetrain also?

Have I just removed all the benefits of lipo by engineering them back out?

I have to believe there is a way to have the power of brushless, but keep the wheels on the ground and your truck in control.

Honestly, I think what we are seeing is a maturity process in the brushless RC truck area. Ya, for now its kool, but all that un-controlled power is going to get old really quick and people will start engineering control into their designes.

Let me know what you think.
Old 06-26-2007, 04:18 PM
  #2  
maxn
Member
 
Join Date: Apr 2007
Location: RSM, CA
Posts: 59
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Troubling observations about brushless . . .

Honestly the throttle is in your control and you do not have to run full-throttle everywhere all the time !

The MambaMax ESC has extensive programming options that allow you to modify the power curve and the start-up torque along with many other things.

I ran a Brushless in my Lunchbox for a while - possible the worst-handling wheely prone device ever - and tamed it into something that would only wheely at full throttle - all the time then - and something that had fairly usable braking too.

Most of the changes you suggest actually negate the advantages of brushless/Lipo - you are probably better to either tame the BL with ESC programming, or else run a mild brushed setup.......
Old 06-26-2007, 04:24 PM
  #3  
rdbruski
Junior Member
Thread Starter
 
Join Date: Jun 2007
Location: Mesa, AZ
Posts: 8
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Troubling observations about brushless . . .

Thanks Maxn. I hadn't thought of being able to program the ESC. I guess I just don't want to buy the wrong setup just to tune it down when I should have bought the right setup to begin with. Know what I mean? Power costs money. If I'm tuning down the power, then I just waisted money cause I over bought.

Also, I don't think all the out of control flipping is from running full throttle. Maybe its just poor ESC programming on the part of the people I see in the video's? Either that or just simply too much power. I dunno.
Old 06-26-2007, 04:42 PM
  #4  
maxn
Member
 
Join Date: Apr 2007
Location: RSM, CA
Posts: 59
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Troubling observations about brushless . . .

I am not sure it is a question of buying the wrong thing to tune it down, more a question of buying brushless and then tuning it to your requirements.

I just put a MambaMax 5700 in a Front-Drive M03 chassis - out-of-the box it simply spun the wheels all the time - 30 minutes of tuning and I have a gentle launch, massive top-end power, 75% braking and supremely driveable car.

Technically I am not using 100% of the available torque - but I cannot use it without investing in super sticky rubber - but the zero (or close) maintenance is a winner for me over a similar priced brushed motor/ESC combo.

I am planning on converting all of my RC's to brushless - I have three already - the 5700 in the M03, a compX 1/18th in the scalpel and a 6900 which is taking a rest after being in my lunchbox it is heading for the TA04 that I am yet to build
Old 06-26-2007, 04:46 PM
  #5  
rdbruski
Junior Member
Thread Starter
 
Join Date: Jun 2007
Location: Mesa, AZ
Posts: 8
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Troubling observations about brushless . . .

Does a brushless system properly programmed to give me controlled power still offer obvious, amazing power over nitro?
Old 06-26-2007, 05:53 PM
  #6  
john01374
 
Join Date: Nov 2006
Location: ABC WORLD, IL
Posts: 2,561
Received 5 Likes on 4 Posts
Default RE: Troubling observations about brushless . . .

In a single word YES. I have never liked Nitro but I have a few friends that swear by it and many swore they'd never go back to Electric. Now that they've seen brushless a few have seen the light. I have my MM5700 in a rusty tamed down to where it's totally driveable, I no longer break parts and it only gets the wheels up when i want it to. All this on a 11.1V Lipo. My Nitro friends hate me. I out run them everywhere we go. I can run my truck anytime night or day (no noise) It's even tame enough to drive around in my house. Try that with a Nitro. Once you go brushless you'll never look back. besides the Lipo battery, Brushless is the best thing to happen to electric RC in the last 10 years. Do it.


John
Old 06-26-2007, 06:09 PM
  #7  
cheech4
Senior Member
 
cheech4's Avatar
 
Join Date: Feb 2006
Location: astoria, NY
Posts: 6,331
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Troubling observations about brushless . . .

i agree, brushless is the best thing besides spread spektrum that ever came to electrics.. most if not all brushless system can be programed either on the ESC itself or via computer program. I also had that problem with brushless being very torquey to powerful and to at start. but after a few little fixes you can tame a brushless. and now its all smiles
Old 06-26-2007, 08:51 PM
  #8  
Access
Senior Member
 
Join Date: Mar 2005
Location: , CA
Posts: 4,900
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Troubling observations about brushless . . .

It's all the driver and not the truck. Most of these vids you see are just people going for the 'wow' factor. They're not focussing on their driving / technical skill for the video. I know I have to hold the camera with one hand the controller with the other, which doesn't do wonders for my driving skill when I make the vids. When you drive it for real, you just have to learn to baby the throttle all that. Look at the way this B4 handles:

http://www.youtube.com/watch?v=e1a1kHW7eh0
http://www.youtube.com/watch?v=vklm5D6Z-HU

Or even this pede:
http://www.youtube.com/watch?v=lkjFzOQF-9E

Two different strategies at work here, the buggy is low to the ground and has a super-low CG, stays stable that way. Maximum traction on the rear wheels, and driven appropiately. Even so, it's possible to spin the rear wheels and flip, if you take it past the limit, but that limit is much higher than a high-CG MT.

The 'pede OTOH is completely newbie-proof on the grass (or dirt) b'cos of the way it slips and slides around. Despite the high CG, the anaconda wheels just don't have enough traction to tip it unless you do something really awful. The rear tires are out farther than the front, if you turn too hard it just understeers, if you accelerate too hard it just loses traction. I always let newbie friends drive the 'pede, they like the way it can fishtail a turn and it's real easy to keep upright.
Old 06-29-2007, 07:59 AM
  #9  
mbeatle
Junior Member
 
Join Date: Jun 2007
Location: Alexandria, VA
Posts: 29
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Troubling observations about brushless . . .

Nice video, Access. I have a MM5700 pede coming my way today, and I'm contemplating whether to keep it or go back to brushed for a more "sane" experience. I agree that all the brushless videos I see are people giving it the beans straight away just to show off the power. I'd rather have a more controlable power curve that isn't bringing the front end off the ground all the time, but I don't want to do it by crippling my off-road truck with anacondas.

A lot of people have talked about taming the brushless monster by tuning the ESC. I know the MM gives you that option, but what settings do you recommend on the MM for a more controllable truck?

I think stiffening the rear springs as much as possible would help keep weight from transferring away from the front and keep it planted. It will also make the car less prone to understeer under power which the pede does ad nauseum. I won't mind an occasional 360 from power-on oversteer. Any comments on suspension setup?
Old 06-29-2007, 09:40 AM
  #10  
john01374
 
Join Date: Nov 2006
Location: ABC WORLD, IL
Posts: 2,561
Received 5 Likes on 4 Posts
Default RE: Troubling observations about brushless . . .

Believe it or not my Pede's suspension uses all stock parts. The rear has a couple of spring spacers and some 50wt shock oil. The front has a 1/4 inch piece of fuel tubing under the shock valve. (Shortened the shock length 1/4 inch) and 30wt oil and no spacers. I'm using the stock XL5 white springs all the way around. It also has the stock Talon tires which are not real good, They spin more than anything else. A change to better tires like the Geo's which have a ton of grip on concrete would make it wheelie more. It's very tame and driveable. I played with the ESC to tame it down but most of the improvement came from learning to control the throttle. I can still pick the front wheels up anytime i want but i can also accelerate to top speed without flipping the truck over or spinning it around. If you decide to go back to brushed and want to sell the brushless set up let me know.
Old 06-29-2007, 10:53 AM
  #11  
mbeatle
Junior Member
 
Join Date: Jun 2007
Location: Alexandria, VA
Posts: 29
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Troubling observations about brushless . . .

What are your settings in your ESC, John?

You have no spacers on the stock springs at all? Do you find the car likes to flip and cartwheel in corners due to the heavy body roll? That's my main concern.

I also have the stock talons. I wish there were more options for 2.8" wheels.

I know driving skill plays the biggest part in how a car handles, but it's more fun when you don't have to bear down and concentrate on it at 10/10ths all the time.
Old 06-29-2007, 11:28 AM
  #12  
john01374
 
Join Date: Nov 2006
Location: ABC WORLD, IL
Posts: 2,561
Received 5 Likes on 4 Posts
Default RE: Troubling observations about brushless . . .

I have spacers / collars (the little plastic clips that go on the top of the spring) On the rear only. One other thing I forgot to mention. I did lower the body down by cutting the body mount posts. The truck will still flip if you're not careful but it's much better than stock. The only way to stop the Pede from flipping is to lower it or put on road tires on it. Then you basiclly have a rusty with big tires. I'm at work so I don't have the settings for the ESC right now. I'll post them tonight.



Old 06-29-2007, 04:07 PM
  #13  
BanditMonster
Senior Member
 
Join Date: Jul 2006
Location: , TX
Posts: 330
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Troubling observations about brushless . . .

Majority of the video posters go for the crazyness of it all, just to put it on video and display the amount of power their system has. Like Access said above, it all depends on what the user wants. Brushless systems will give you far more adjustability than nitro powered engines. They are two different worlds anyway.

Then you have the people who want power AND control at the same time

http://www.youtube.com/watch?v=3I9kzZjPxdI

It's no different than getting a nitro-powered touring class model and putting a very powerful engine in it.

You can have a T-Maxx with an after-market super powerful engine that will do what you see people do in the videos with their brushless systems.

It doesn't matter what the source of your drive is, it matters on how you want to use it.
Old 06-29-2007, 08:50 PM
  #14  
RURC
 
RURC's Avatar
 
Join Date: Nov 2002
Location: Saint Petersburg, FL
Posts: 1,705
Received 0 Likes on 0 Posts
Default RE: Troubling observations about brushless . . .

This some of the best replies I have seen in a while. Congrats to all.

Now brushless can be done from mild to insane. The problem is that most people use the first several packs to see how fast they can wear out a set of tires. Then they settle down and start learning about what they really have. But what you see in the videos is those first packs. I have built rock crawlers and they were slow with lots of torque to pullup rocks. I have made cars that exceed 100 mph with relative ease but they can be turned around and run on a track or just bashed down the street with ease. My son really likes driving those cars. They respond and drive like they are on rails at 60 to 70 mph. Then with a simple change of batteries they launch like a rocket and the hardest part is keeping them on the ground. So plan you car/ truck as a complete unit and you will not be dissapionted when you are done. You need to look at every part and plan how to get the most out of it for what you have in mind for the whole thing. Good luck and have fun.
Old 06-30-2007, 03:55 PM
  #15  
mbeatle
Junior Member
 
Join Date: Jun 2007
Location: Alexandria, VA
Posts: 29
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Troubling observations about brushless . . .

My brushless pede is very keen to flip. Due to cogging problems, I did not get a chance to really evaluate the suspension, but the speed is just absurd, even geared 16/86!

I have spacers with the stock white springs: thickest in rear, second thickest in front. Wheelies are not the problem I thought they were going to be with brushless, but the previous owner may have had the slipper clutch a bit too loose. I actually wish I had a bit more torque down low. With the stock motor and IB4200 cells, I get massive understeer with the hammer down, and it flips with a quick lift of the throttle in a fast corner, even when I try to counter steer.
Old 06-30-2007, 06:31 PM
  #16  
RURC
 
RURC's Avatar
 
Join Date: Nov 2002
Location: Saint Petersburg, FL
Posts: 1,705
Received 0 Likes on 0 Posts
Default RE: Troubling observations about brushless . . .


ORIGINAL: mbeatle

My brushless pede is very keen to flip. Due to cogging problems, I did not get a chance to really evaluate the suspension, but the speed is just absurd, even geared 16/86!

I dont get suprised too often but flipping due to cogging really dose not make since. Cogging will not apply power in one direction to flip a truck. If you are getting a burst for that long there is something not right. Also you mentioned torque. With electric motors you get about 96% of full torque from 3 rpm, depending on the efficiency of the motor this can be more or a little less. So for all real talks basically you get the same torque from 1 rpm up to wattage max of the weak link in the system.
Old 06-30-2007, 11:01 PM
  #17  
mbeatle
Junior Member
 
Join Date: Jun 2007
Location: Alexandria, VA
Posts: 29
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Troubling observations about brushless . . .

Sorry to confuse. I had cogging issues that prevented the truck from even running after half the battery was drained.

It felt like the motor was a little slow to get off the line. After it was going a few mph, it really poured on the speed and flew. This was geared at 16/86. I'm not sure what his settings were for the ESC. Maybe he had dialed in a lot of restriction. We'll see once I get it back in the truck.
Old 06-30-2007, 11:19 PM
  #18  
RURC
 
RURC's Avatar
 
Join Date: Nov 2002
Location: Saint Petersburg, FL
Posts: 1,705
Received 0 Likes on 0 Posts
Default RE: Troubling observations about brushless . . .


ORIGINAL: mbeatle

Sorry to confuse. I had cogging issues that prevented the truck from even running after half the battery was drained.
This is one of those problems where the 'cogging' was a symptom not the root cause. I have talked about such things but there are those that will not listen. I am not trying to change this thread but this is something that dose not happen every day.
Old 07-01-2007, 06:07 AM
  #19  
Access
Senior Member
 
Join Date: Mar 2005
Location: , CA
Posts: 4,900
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Troubling observations about brushless . . .

These days people just use cogging as a catch-all word to describe a certain symptom. You just need a better battery or less system resistance. Real cogging is something else.

I haven't driven a truck/buggy/car yet where I couldn't flip it on a corner if I did something I shouldn't do. Even stock RTR stuff. Have you tried adjusting the anti-squat setting?

As for the cogging, it can flip a truck, esp. light stuff. More what you have to do to get around the cogging. If you have to jam the throttle down to get it moving, once it starts to move it can flip. This is how my mini-T was at first.
Old 07-01-2007, 09:13 AM
  #20  
mbeatle
Junior Member
 
Join Date: Jun 2007
Location: Alexandria, VA
Posts: 29
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Troubling observations about brushless . . .

Better batteries than a matched IB4200 pack? I know there's lipo, but you shouldn't need that to eliminate cogging. I think it may just be a loose wire between the ESC and motor.

At any rate, when the truck was running properly, it wasn't cogging. What is the anti-squat setting? Big spacers in rear?
Old 07-01-2007, 10:18 AM
  #21  
Slo-V Flyer
Senior Member
 
Slo-V Flyer's Avatar
 
Join Date: Feb 2006
Location: Arlington, TX
Posts: 3,344
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Troubling observations about brushless . . .

ORIGINAL: mbeatle

Better batteries than a matched IB4200 pack? I know there's lipo, but you shouldn't need that to eliminate cogging. I think it may just be a loose wire between the ESC and motor.

At any rate, when the truck was running properly, it wasn't cogging. What is the anti-squat setting? Big spacers in rear?
Anti squat is the angle of the rear arms, specifically, the angle where the hinge pin crosses the main mounting on the chassis. Basically, the front of the hinge pin should be a little higher then the rear as it goes through the hinge, kind of like a subtle version of how the front of of the front arms are angled upward. This angular setting of the rear arms prevents the rear end from lowering a certain amount. BTW, the Rustler/Stampede tranny as built-in anti-squat setting where the arms mount to, if you look carefully.
Old 07-01-2007, 12:04 PM
  #22  
RURC
 
RURC's Avatar
 
Join Date: Nov 2002
Location: Saint Petersburg, FL
Posts: 1,705
Received 0 Likes on 0 Posts
Default RE: Troubling observations about brushless . . .


ORIGINAL: mbeatle

Better batteries than a matched IB4200 pack? I know there's lipo, but you shouldn't need that to eliminate cogging. I think it may just be a loose wire between the ESC and motor.

At any rate, when the truck was running properly, it wasn't cogging. What is the anti-squat setting? Big spacers in rear?
IB4200's are not capable of supplying the needed amps to fully run a Mamba Max system depending on the esc settings period. THe mamba Max can draw 100 amps continous IB's cant even come close to that.
Old 07-01-2007, 01:44 PM
  #23  
Lilredmachine
Senior Member
 
Join Date: Jan 2006
Location: Shanklin, UNITED KINGDOM
Posts: 1,929
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Troubling observations about brushless . . .


ORIGINAL: RURC


ORIGINAL: mbeatle

Better batteries than a matched IB4200 pack? I know there's lipo, but you shouldn't need that to eliminate cogging. I think it may just be a loose wire between the ESC and motor.

At any rate, when the truck was running properly, it wasn't cogging. What is the anti-squat setting? Big spacers in rear?
IB4200's are not capable of supplying the needed amps to fully run a Mamba Max system depending on the esc settings period. THe mamba Max can draw 100 amps continous IB's cant even come close to that.
Agreed, you need heavy duty lipos to get the most from a brushless setup. The most you'll ever be able to pull out of (even matched, zapped IB 4200) NIMH cells continuously is about 40 amps, anything more than that and the voltage drops real fast. My Revo/E-maxx hybrid runs a little feigao 380 XL motor with a CC Phoenix 80 (with a UBEC) on 14 cells through a Revo FOC tranny, mounted on a Kershaw racing chassis stretched 1 1/4 inch over stock. Even with the small motor she'll run 40mph and pull the front up on the 1st to 2nd shift. I really want some lipos as the NIMHs really struggle to give up the juice my mild as hell set up demands. You don't need a sick set up to have sick power, a well set up system will give you the speed you need without the uncontrollable flips and wheelies.
Old 07-05-2007, 10:15 PM
  #24  
morespeed
Senior Member
 
Join Date: Dec 2005
Location: greenville, NC
Posts: 235
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Troubling observations about brushless . . .

anybody know what the novak 8.5 supersport motor draws in amps compared to the
MM5700. i know the MM5700 IS 100A.
Old 07-06-2007, 11:54 AM
  #25  
RURC
 
RURC's Avatar
 
Join Date: Nov 2002
Location: Saint Petersburg, FL
Posts: 1,705
Received 0 Likes on 0 Posts
Default RE: Troubling observations about brushless . . .

ORIGINAL: morespeed

anybody know what the novak 8.5 supersport motor draws in amps compared to the
MM5700. i know the MM5700 IS 100A.
The pro is 280 watts and the standard is 225 watts. That works out to be 39 amps for the pro and 31 amps for the standard. That max with the max voltage of 7.2 volts. This is the biggest reason that the Novak and LRP work so smoothly with nixx batteries. They dont draw that much power comparatively. The esc is rated at a max of 120 amps for brakeing only. I dont know how they separate this out but this is their spec not mine.

The Mamba Max esc is rated at 100 amps continous (not max) in foward or reverse with peaks higher than 200 for moments. I have seen 265 amps for 1.5 seconds useing a Eagle Tree data logger goos to 300 amps. I have seen the meter peg out for 1/2000 of a second in 1/8 scale buggies. Both of these were under brakeing (where the highest current draw occurs) and had no effect on the working of the esc.

The CM36 motors (the green motors that they sell with the Mamba Max esc) are rated at 1000 watts. This translates to 139 amps with the same working voltage of 7.2 which is a 6 cell nixx battery. This is why I tell people that nixx batteries, no matter the brand, can not begin to supply the current that a Mamba Max with the CM36 motor CAN draw. But still there are those that argue with me on this. Pitty they will not look at the math and understand.

Now when you say the MM5700 I assume that you are talking about the Mamba Max esc with the CM3657 motor. People need to make a clear distinction on this. THe Mamba Max is the esc not the system or the motor just the esc. When you see a post that just says MM or Mamba Max this dose not mean that they are useing a CM36xx motor. I only have 2 CM36xx motors and 12 Mamba Max esc's. Just a note to try to help.

Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service -

Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.