The Adventures of Building a Race Worthy Brushless Electric 1/8 Scale


On going discussion at RC Universe is here

Entry I:

Project updates will be posted on the thread as comments so we can try to keep this a "linear timeline" BBS conversation.....

We thought about a 1/12 scale Jammin CRT.5 stadium truck chassis, but as we intend to race and there isn't a class for that we went all out with a 1/8 scale buggy. (Editors note, I feel this 1/8 scale buggy brushless conversion racing head to head against Nitros to be the most excting thing going in RC racing, and predict this summer will see LOTS of RC media attention).

See the 1/8 scale buggy and truggy results in the following link for our local peer group, which have been mucho helpful as we asked a thousand questions during our project design, parts selection, and test track phases. THANK YOU GUYS.

http://www.rcproductdesigns.com/washtenaw_track.htm


The project: Pick up a mint condition used Jammin X1 CR sans un-needed nitro engine, for a small fraction of retail. Then select and pick up some odds and ends spare parts for motor mount and battery tray. Start working on a plan for battery, speed control, motor, other control devices, cooling engineering, and "additional" ancillary equipment.

Choices to be made RE motive power: Since we already have a pair of 7.4 volt 4000 mah MaxAmp LiPos, we plan to run them in series for 14.8 volts and 4000 ma. The ideal motor seems to be the NEU but they also seem to be hard to come by, so we're starting out with a Feigao 540 7XL. Most folks we know are running the Castle Mamba Max (MM), but since we already have a Traxxas VXL it might be fun to use it if it will work, the primary concern being the "Over voltage" feature crapping us to "failsafe" mode. With the 3 cell LiPo rating of the VXL giving us 11.1 volts and the spec rating of 200 amps the VXL should have wattage handling capability of 2220 watts. If we can run @ 14.4 volts, the Feigao runs at 95 amps max, which would only tax the VXL to 1368 watts which it might seem we have some power handling breathing room.

With the rumored Castle Mamba Monster Max (MMM) on the horizon it would seem pointless to spend the money now for a current MM if the VXL will do the job.

The folks on the track seem to run with the MM ESC now with some success but they also do have to manage heat carefully with little room to spare. They also prefer to run the NEU motor rumored to run more efficiently than the Feigao (4 poles vs 2 poles).

Some cooling engineering with heat sinks and fans of course needing to be part of the master plan.

Numerous trade Mags have done "reviews" of prototype set ups, one even including wood parts!

Numerous vendors are selling various conversion parts at various price points, some ESC / motor vendors are selling "systems" although this market seems to be underdeveloped and in its infancy.

I'm most impressed with the engineering and proving ground efforts of www.RCProductDesigns.com although many others have also worked on developing this new frontier.

Anyone care to discuss the various pros and cons of the various motor options in this higher power range?

Experience at pushing the Traxxas VXL to higher performance ranges? Other ESC options?

Experience with running multiple fans and devices with a BEC?

Gearing experience with various size and surface characteristic tracks?

Experience with various LiPo sizes working for the duration of various time length mains?

Experience with optimal steering servos for the heavier vehicle?

Other racing issues such as ROAR sanctioned or exhibition events?

Links:

www.RCProductDesigns.com *

See RC Driver January 2008 edition, "Projects" (not available on line). http://www.rcdriver.com

http://www.rcuniverse.com/forum/m_6985716/anchors_6987110/mpage_1/key_/anchor/tm.htm#6987110

http://www.rcuniverse.com/magazine/article_display.cfm?article_id=953

*Not affiliated with RC Product Designs (other than occasional customer)

Pictures / performance testing as the project develops.......



Entry II:
quote:

ORIGINAL: helishack

I ordered an 11T hardened pinion (MOD1) from RC-Monster. I'll order larger sizes as I learn more. The aluminum for the motor mount was from the "hobby" pile at the local metal supply company (0.25 per piece - what a deal!).

Any observations, comments and suggestions are appreciated. By the way, this project cost me 1 hour and about $18 (for the pinion and the 4 aluminum "hobby" pieces.

I'll follow up after I get the ESC and install it. From there I'll work on the gearing and final motor selection.

Jeff



Thanks for the great details. We picked up a motor mount from eBay, and a used battery tray from the local track.

Starting from scratch, we had to buy a motor (Feigao for around $80), the NEU being the motor of choice but it runs for around $240 list price and seems to be in short supply as they (NEU) are ramping up with this segment of the market?????? (NEU seems to be big in the RC airplane world).

Various other parts on the way, steering servo, BEC etc etc.....

Then there's the new tires and rims, body, we didnt have an 1/8th scale to begin with, this project would be a lot easier for existing Nitro owners as many of the basics would be in place.

The Mod1 pinions seem to be the suggested gears of choice, and although they are said to work with the stock metal spurs, the Kyosho 46 plastic spur seems to be the most recommended for best pinion wear. The hardened pinions at $12 or $13 each plus mailing vs $5 for the plastic spur which is also said to hold up very well. Running with the plastic spur, there is also some doubt the extra expense of the hardened pinions are required, and regular steel pinions will work OK.

Of course, once we actually get to powered testing, performance on the track under race conditions will be the proof in the pudding.

The guys at the www.RCProductDesigns.com Forum have LOTS of experience and have helped us out a great deal on shortening the learning curve. In the "Washtenaw Track" section are results from the 1/8th scale rigs under race conditions on a small indoor track and running 5 minute races. The outdoor race conditions being another story with bigger tracks and longer races making heat management, batteries, and gearing all more intense and needing careful attention.

We hope to run for the first time next weekend, will update with more details and lessons learned as we get to actually rolling on the track condition.

I'm REALLY curious how hard we can push the Traxxas VXL ESC and how it will perform compared to the MM.



Entry III:
quote:

ORIGINAL: helishack

I wasn't aware of RCProductDesigns. Thanks, I'll check them out. I was going to simply order a motor mount, but for $40-$60 (versus .25 cents) I decided I'd drill and tap one out myself. Actually, I did break a $3.50 tap and had to use a second piece of aluminum so the total motor mount cost went up to $4.00. Darn it! Actually, I will have to re-machine the bolt holes for the motor when I add a larger pinion. I need to allow for the motor to be moved away from the center diff as I try different pinion sizes.

Let's keep this poject going and everyone informed. It's a lot of fun and I'm sure it will be plenty worth it in the end.

Jeff




I emailed Dan at RC Product Designs, hopefully he'll keep an eye out on this post and share some lessons learned from time to time.

For us do-it-yourselfers, buying the Traxxas E-Maxx motor mount for about $6 gives a good cheap pattern for copying the geometry for making new motor mounts (or just use half of it). It seems an inexpensive time and trouble saver for taking measurements and making prototype parts. We thought about a dual Velineon set up for awhile and were going to use the motor mount, but decided to keep it simple and stick with one motor (we think dual brushless on the same spur might be a feedback and motor control problem).

You're very welcome for the thread, we plan on racing competitively this coming summer and as we take pics and get some testing results I hope to keep this thread updated. Hopefully others will also add their projects like you did - we can all learn together.



Entry IV:
quote:

ORIGINAL: RichieD

14.4 volts isn't enough voltage; and that is the worst botch-job I have ever seen!


Well RD, as said by the owner of the "botch-job" I also appreciate your input. I would ask that we keep the "tone" a little more up beat and condusive to working together.

My impression is that Jeff, just like myself is experimenting with some prototype parts development and in the interest of the creative process, our parts may well be a little rough around the edges at first, but in the spirit of "why pay retail" when you can do-it-yourself - our end results may well be lighter, stronger, and cheaper.

As far as 14.8 volts (4 cell LiPo), it seems to be a basic price point threshold. The cost of the batteries, and ESC that operate in this range (Mamba Max) being sort of the entry point to being fast and reliable. If we want to upgrade to 5 cell or 6 cell (LiPo) batteries, we can also probably expect to pay $100 more for the ESC. The soon-I-hope Mamba Monster Max may open some new doors for power / performance / price point. I'm not entirely sure what higher voltages the NEU motors will handle as I don't like to quote numbers and techno facts from memory, but I can tell you that the Mamba Max coupled to an NEU and 4 (or 5 cell) LiPos absolutely fly around the track. You might also find in the various trade journals and discussion boards, many folks are operating at the 14.8 volt range (many in recent years also using sub-C cells) and quite pleased with speeds. Managing heat being the key to success. I have a few ideas in this area, not yet done with developement and testing or ready to share.

The head to head comparison of the LOSI 8ights was enlightening:

http://www.rcuniverse.com/magazine/article_display.cfm?article_id=953

An interesting point of note, they ran with 11.1 volts.

I'm not an electrical or electronics engineer (actually I do heat and cooling engineering), and we aren't talking laboratory bench testing with dynamometers here, not to mention speed runs on the Bonneville Salt Flats - what I want to see is head to head on the track for 30 minute mains in 100 degree summer heat. May the best man (or woman) win.

That all being said, I'm told the currently available HV package (from Novak?) doesn't perform, it was designed for an E-Maxx instead of a racing 1/8 scale buggy, and in all honesty - those of us do-it-yourselfers can be credited for inventing this new RC opportunity.

And besides, as an old fart I like the peace and quiet of the electrics over the Nitro. But like I said above, the proof will be in the pudding - NOT just on the track, but also in the elegance of our designs, and the robustness of our rigs.

Jeff was kind enough to share the early development stages of his project, I hope to also as soon as possible.

Please feel free to share pics and performance of your project(s) also. This is an open invitation to everyone to share their projects, that's why I started this post - so we can all learn.


Here is a link to "patented" conversion kit history from 2005. Lots of discussion and pics (albeit one must be a member to see the pics).

http://forums.radiocontrolzone.com/showthread.php?t=196185

Here is a link to further discussion RE the RC Product Designs conversion kits. LOTS of discussion RE braking differences between the traditional front / rear adjustability of the Nitro setup and the breaking via the motor of the Brushless setup.

http://rctech.net/forum/showthread.php?t=158327


Discussion Link RE motors / gears / power / heat / maintenance and reliability:

(mostly Feigao and NEU but engineering issues apply to any motors)

http://forums.radiocontrolzone.com/showthread.php?p=2309019


Entry V:

Following is a brief summary of the motor mount we decided to try for Phase I:

We picked it up on eBay for $25. It seems for material selection, measuring and machine time, it was worth the cost for a quick and inexpensive place to start. As noted above, our thoughts for a dual Velineon system and the Traxxas E-Maxx motor mount were discarded for a sinlge motor / ESC design.

First trouble we had was the lower bracket portion was above the chassis so we had to make a spacer to mate up properly. Second, the central diff drive hole was not positioned properly to match up to the diff mount screws. We were able to get around these with some "adjustments"

We also made our own "shelf / bracket" for electronics mounting, so we did not use the top plate that came with the package.

I like the idea of using angle stock, as I think the lower bracket anchored to the chassis will provide stiffness given the weight of the cantilevered motor would normally only be supported by either just bolts thru the bottom, or anchoring to the diff assembly.

We will also be "skeletonizing" it for weight reduction and increased surface area for inhanced passive cooling for the motor.

Below is a picture of the base part, more from our buggy in the coming days and weeks as we put it together and begin testing under power:


 



Entry VI:
quote:

ORIGINAL: ecocav04

i hate to break it to you but thats not a jammin x1 cr. i have no idea what that thing is



The fellow above (helishack) who posted the pics is doing / the pics are from a separate project from the HandyRacing Jammin project.

Thanks for looking close enough to notice though. When we get our project / pics together there will be two projects being shared within this Post, hopefully more as we go along. Thanks.


Entry VII (project update after track testing):

Project Update I

Sorry for the delay, lots of things have been happening and its been tough to slow down long enough to write.

When we posted the original article, we were in the final phase of component selection. Batteries were in hand ( a pair of 7.4 volt / 4000 mAh with plans to wire in series for 14.8 volts), we had plans to implement our racing phase with an NEU motor but due to cost and time constraints we went with a Fiegao so we could get our testing platform on the track sooner. We expect the 4 pole NEU to be more efficent for battery life, run cooler, with more power than the 2 pole Fiegao. Stay tuned for this summer's racing on that part of the program.

The remaining component selection decision was which ESC to go with. When we found out the hi voltage cut out on the Traxxas VXL was around 12.5 volts it more or less became a done deal, no VXL, as it just wouldn't perform under the higher power we wanted - so we bought a CC Mamba Max. While the MM is rated to handle up to a 3 cell LIPO, its also known to actually handle 4 cell and even 5 or 6 cell LIPO voltages. There is the added (crucial) benefit of being able to program in custom throttle curve and breaking profiles, as well as LIPO cut outs.

( Editors note, maybe higher voltage at lower amps is less heat stress on motor / electronics? )

Once we were committed to battery / motor / ESC - the next thing was to pick up the steering servo (we went with a $30 Futaba high torque metal gear servo with ideas to buy a more expensive higher performance servo if needed for racing), we selected the Castle Creations BEC to run the receiver and servo and one cooling fan, picked up a couple of cooling fans from various sources and ended up running one fan (Integy) off the BEC to cool the bottom of the ESC (by drilling holes in the case) and a small Radio Shack 12 volt fan running directly off the battery to cool the top of the ESC (by blowing directly across the heat sink).

We went with an www.rc-monster.com heat sink / support bracket borrowed from a friend at the track to support the (known weak endbell) Fiegao motor, we still need / want to figure out a better cooling setup for the motor, design a fan mounting for a follow up.

We then had to actually figure out the precise wiring harness arrangement. As it turns out the way we mounted the ESC, receiver, BEC and connectors all to a custom made top plate running between the center diff to the rear bulkhead - it all ended up being a modular type arrangement so we could easily lift the entire assemblage away for service to the drive train. (See spur / pinion gear discussion).

We also went with bullet connectors for the (3) motor leads, and Dean's for the battery Y-harness and associated connections to the ESC (all this leaves us with a non-solder setup for quick turn around service and repairs on race day).

Up till the wee hours, we finally called it quits with a few remaining loose ends to deal with the next morning prior to practice / racing.

Up again a few short hours later, first thing in the AM after arriving at the track we charged our batteries, finished with last minute wiring and component connections, and powered up the rig.

No smoke. WHHHOHOHOHOHHO

We made our motor installation wiht a 12 tooth pinion mated to a 46 tooth Kyosho plastic spur.

First thing out on the test track we picked up a small stone and ripped ONE gear out of the spur by the roots.

Craptastic.

2nd time out on the track for testing, our pinion came loose and scored the motor shaft and pinion bore. We were able to clean the burry off the motor shaft and with a borrowed 11 tooth pinion we were back in action (we were unable to quickly clean out the bore of our 12 tooth pinion and had no backup).

We completed the first (5 minute) heat race, finishing with a respectable time / lap count - but more than anything SUCCESS with finishing the race - BOTH with a brand new rig, and with a driver who was driving it for the first time under race performance conditions. WAY TO GO.

2nd heat race, we stripped out the spur gear and didn't finish. 3rd heat race, came close to finishing, but again stripped out the spur gear and didn't finish.

Close inspection revealed we were having trouble getting close enough to the spur on our gear mesh adjustment due to our motor bumping into the chassis center brace. Apparently the difference between and 11 and 12 tooth pinion diameter was enough to obstruct our freedom of movement for motor / gear mesh adjustment.

To solve the problem we figured out a way to clean out the bore of the 12 tooth pinion and put it back in and were re-assembled in time for the main race.

Not only did we finish, but we completed the race with good time and on the lead lap with the rest of the pack (except the winner who got the extra time around for an 11th lap). OUTSTANDING.

I would love to take pictures, but the digital camera has gone missing and still not ready, however I do have a couple of blurry pics from race day via the camera-phone.

(I know, clear as mud):

 




Race results for those folks who want to see how performance under race conditions pan out:

http://www.rcproductdesigns.com/documents/WASH2007/Mains%202-16-08.htm


Entry VIII (first Summer 2008 racing outing):

Summer 2008, MORL Jones event 1/8 Scale A-Main electric conversion race footage is here:

http://www.youtube.com/HandyRacing

- or just view it here -




Following are some great pics from the track, (big thanks to the MORL folks):













All ideas and resources are USE AT YOUR OWN RISK.  This is Hi-performance RC, YOU are responsible for your project decisions and results at all times including while bashing in the yard or racing on the track.  That includes running over Nitro rigs that get in the way.

(Spell check and minor sentence structure edits as we go along)

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Posted by HandyRacing at 6/26/2008 11:49 AM
Categories: Building a Racing Rig
 

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