R/C Tech Forums

Go Back   R/C Tech Forums > General Forums > Electric On-Road

Reply
 
Thread Tools Search this Thread
Old 06-24-2008, 02:33 PM   #136
Tech Elite
 
Join Date: Aug 2002
Location: Houston, Texas
Posts: 3,777
Trader Rating: 27 (100%+)
Send a message via AIM to John Stranahan
Default

I thought I would do one more test while this 3.5 was hooked up. This time is used a 4 cell pack. This pack can deliver the huge amps this motor needs to perform at its best. It is not like a 6 cell and at this point I don't recommend running the dyno with a 3.5 and a six cell pack. It is starting to sound like a small jet engine already due to the 48,000 RPM reached. Note that without using the Fantoms power supply you can get no efficiency numbers. The dyno cannot measure input power.

In the red corner the small rotor peaked about 140 W. I got very smooth data an did not need a trendline. In the green corner the large rotor 123 Watts. This large difference did not require replicates on this smooth data. you get more power with the little rotor. This is a repeat of the conclusion with the 13.5.

Pic: Note the white scatter shield has a beveled cut so it's supported by the black knob as well as a strip of tape. Aim the exposed part of the flywheel into a safe area. Note that pile of papers; that is two years receipts for RC stuff. Damn. Don't tell the wife.
John
Attached Thumbnails
CRC Battle Axe, GenXPro 10, 1/10th pan, Brushless, Lipo,4c, Road, Oval,TipsandTricks-power-vs-rpm-novak-3-5-r-both-rotors004.jpg   CRC Battle Axe, GenXPro 10, 1/10th pan, Brushless, Lipo,4c, Road, Oval,TipsandTricks-scatter-shield.jpg  

Last edited by John Stranahan; 06-24-2008 at 02:52 PM.
John Stranahan is offline   Reply With Quote
Old 06-24-2008, 03:15 PM   #137
Tech Regular
 
Join Date: Aug 2005
Posts: 308
Trader Rating: 1 (100%+)
Default

Very interesting testing John.

I suspect the different efficiency readings may have something to do with the balance of the rotor. I have made some rude atempts to balance brushless rotors, and i have found that smaller rotors seem more balanced than wider ones.

I still have the impression the larger rotors produce more torque for a given consumption than a smaller one. This can be seen for example by the difference in the brake settings. Tipically i will run a 13.5mm with 25-35% brake. The same motor will need 45-60% for the same braking power. it seems to me that more amps are needed for the same power output.

In any case it seems the most interesting feature in runing smaller rotors is that shift in the powerband you mentioned. For me its way more confortable and the consistency in my laptimes shows that.

Again, thanks for the interesting info

EDIT: just read the last post. I stand corrected. The smaller rotor is more powerfull all the way. I would never guess that by real track feeling though.
Itchy is offline   Reply With Quote
Old 06-24-2008, 04:25 PM   #138
Tech Elite
 
Join Date: Aug 2002
Location: Houston, Texas
Posts: 3,777
Trader Rating: 27 (100%+)
Send a message via AIM to John Stranahan
Default

Itchy thanks for the post. You are very welcome.
"I still have the impression the larger rotors produce more torque for a given consumption than a smaller one. This can be seen for example by the difference in the brake settings. Tipically i will run a 13.5mm with 25-35% brake. The same motor will need 45-60% for the same braking power."

I agree with your assesment of braking. Braking has to do with reverse voltage. Under braking the armature acts like a generator; the winds are shorted to produce brakes. The more "reverse" voltage the motor produces the better the brakes. It seems from the testing that the big armature does produce more reverse voltage, this makes it act like .5 more winds on the stator. More winds also produces more reverse voltage. Fewer winds produces the least reverse voltage and let's the motor rev up to these huge RPM's. (Reverse voltage limits motor RPM when it equals input voltage.)

There may be some other tricks played on the newest LRP TC edition speed control that increase brakes to levels that bruhsed motors have. It may be some application of reverse power rather than simply shorting.

I agree that it is a little hard to tell the difference between the two rotors on a wide pan. Yet we still picked the small one. I think this has something to do with insufficient forward traction. On a four wheel drive touring car the difference between winds and rotors is more clear cut.

As far as saying more torque, I would have to make another plot. We often get that phrase completely backwards. Motors with better bottom end punch often have more RPM and less torque. That shifts that motor power peak to the left to lower RPM and more amperage.
John
Attached Thumbnails
CRC Battle Axe, GenXPro 10, 1/10th pan, Brushless, Lipo,4c, Road, Oval,TipsandTricks-torque-vs-rpm-novak-3-5-r-both-rotors005.jpg  

Last edited by John Stranahan; 06-24-2008 at 04:47 PM.
John Stranahan is offline   Reply With Quote
Old 06-25-2008, 01:40 PM   #139
Tech Elite
 
Join Date: Aug 2002
Location: Houston, Texas
Posts: 3,777
Trader Rating: 27 (100%+)
Send a message via AIM to John Stranahan
Default

Wide Pan On Road
A couple of recent developments. First I had Ricks Rubber caps. I had just enough to outfit the wide pan car with a set. The compound was pink and and was hooked up very well on a 145 F track on the oval car. I tried them at 117 F on the wide pan. I had to substitute the narrow pink left rear for a blue. I had sufficient and good steering with the pink compound. I needed a little softer than blue on that one rear. I did have one pink rear but not the two I needed. It showed some promise, But I had a lot of spins from loss of rear traction. I was geared 96/12 with a Novak 3.5 which is as low as I can go. The caps are a bit bigger than a new foam.
Note I had the color wrong on a couple of previous rubber cap posts. I had tried a used set on the oval which were all pink compound. I corrected those posts today.

The second pic shows a front diffuser on the car which is upside down. It was found in GTP racing that this is a good way to keep the front of the car from going airborne. It works like this. The rotating front tires are always sucking a good amount of air under the front air dam. The diffuser takes this airflow and expands it creating a partial vacuum in just the area needed for front downforce. Having that space in front of the chassis covered with a pan (the bumper bottom in this case) is also helpful in preventing blowovers.

I had tried this diffuser previously in LEXAN on a high speed attempt with this same pan car. It did increase the speed attained on a rough slick course by 10 mph which was radar measured. I tried it on the track but it proved to be too delicate. A bump with the boards would bend it so it dragged the track. This current diffuser is built into a BSR142 lightweight foam bumper that I got at stormer. The bumper has a smooth semi rigid bottom and then regular bumper foam on top. Anyway this might give you some ideas if you lack front high speed traction or have blowover problems at high speed. The bumper is very light.

Pics:Wide pan with caps, Wide pan with diffusers, Nissan 300Z from Mcallister for a wide pan in two paint schemes.

John
Attached Thumbnails
CRC Battle Axe, GenXPro 10, 1/10th pan, Brushless, Lipo,4c, Road, Oval,TipsandTricks-wide-pan-rubber-caps-resized-001.jpg   CRC Battle Axe, GenXPro 10, 1/10th pan, Brushless, Lipo,4c, Road, Oval,TipsandTricks-wide-pan-front-diffusers.jpg   CRC Battle Axe, GenXPro 10, 1/10th pan, Brushless, Lipo,4c, Road, Oval,TipsandTricks-mcallister-stock-car-002-resized.jpg   CRC Battle Axe, GenXPro 10, 1/10th pan, Brushless, Lipo,4c, Road, Oval,TipsandTricks-mcallister-nissan-300-z-pan-body-slammed-004-resized.jpg  

Last edited by John Stranahan; 06-25-2008 at 03:30 PM.
John Stranahan is offline   Reply With Quote
Old 06-26-2008, 10:41 PM   #140
Moderator
 
Pro ten Holland's Avatar
 
Join Date: May 2003
Location: Druten/Holland (Europe)
Posts: 1,677
Trader Rating: 1 (100%+)
Default

Here's a video of one of the A mains of last weekend's RC Le-mans race in Bad Breisis:
http://www.youtube.com/watch?v=xVbHecGqVLw
Pro ten Holland is offline   Reply With Quote
Old 06-26-2008, 11:59 PM   #141
Tech Master
 
espresso1967's Avatar
 
Join Date: Mar 2008
Location: Los Angeles
Posts: 1,102
Trader Rating: 18 (100%+)
Default

Thanks for the share, must have been a wicked time. Can't wait to take my crc out next weekend.
__________________
www.cityofangelstshirts.com
espresso1967 is offline   Reply With Quote
Old 06-27-2008, 02:31 AM   #142
Tech Regular
 
Join Date: Aug 2005
Posts: 308
Trader Rating: 1 (100%+)
Default

Great video! I have a weak spot for Le mans bodies :P
Itchy is offline   Reply With Quote
Old 06-27-2008, 02:55 PM   #143
Tech Master
R/C Tech Elite Subscriber
 
Join Date: Jul 2007
Location: Mooresville, NC
Posts: 1,187
Trader Rating: 21 (100%+)
Default My Car

Thanks John ... got the car back today only one thing missing ..... That nicely painted body???????????

Oh well, guess I have get my own then. I'll include photos and progress I am having with the car.

I will be following this thread in the further.

If at anytime I can be of ANY help, you know where to get me.

Question: I was thinking of buying CRC Gen 10 but............ and one have a real good suggestion for a pan car?
__________________
Rick "Blue" Sieboldt - Mooresville, NC
* Associated T5M * Tekin * TQ Wire *
www.tqracing.com/rc_products.htm For all your wire needs

Last edited by lidebt2; 07-28-2008 at 08:10 AM.
lidebt2 is offline   Reply With Quote
Old 06-27-2008, 04:13 PM   #144
Tech Elite
 
Join Date: Aug 2002
Location: Houston, Texas
Posts: 3,777
Trader Rating: 27 (100%+)
Send a message via AIM to John Stranahan
Default

Rick-thanks for the delivery report. I did send a set of decals. Just put window masks first. Then masking tape on the yellow parts. Paint the green, then pull off tape and paint the yellow. I would have done it but did not know if you would have liked the color scheme. It did look nice but not so nice at the moment. It took some hits.

Mathijs-Thanks for the video. I noticed that first hairpin (there was some contact with the leader there) gave the cars some trouble. The line has some white material coming out of it. The cars had a tendency to oversteer there. Was there some dust coming off the inside of the corner. I noticed a nice wide entry into that first hairpin followed by a tight entry into the second. Much like my two hairpins. Were you guys able to brake at all into the second hairpin.

As far as the CRC Gen X 10. I think you will find the problems of the battle axe absent on this car. There is a full assembly manual. I did assemble one Gen X 10 car with no problems at all. There are parts available on the web site now. I agree with some posters on another thread that they should ship by priority mail as well. It is beating the UPS ground by many days at the moment. Note that the front axle nut is tightened just enough to remove side play on the wheel. If tighter, the wheel is under huge friction by side loading the bearings and will not turn. Tighter still and the thread will pop off.

Associated RC10 R-5
I thought this would be a good time to discuss the coming RC10-R5. Lightened spy shot below. Firstly R means road. This will be a 200 mm road car. The RC10 is the grandaddy of all pan cars. So much so that the front Associated suspension is used as is on many offerings.
You will find that the R5 has adopted the center pivot side link rear suspension which has been popular on CRC's offerings for quite a while. Associated found out as did I, that you get a little better forward traction through the bumps with the center pivot side link suspension. The t-plate car sounds better through the bumps and does not bottom as easy, but it patters more over the top of uneven side to side bumps and thus has less forward traction. The T-plate does great on smoother tracks or carpet. Note that on the 1/12th offering the T-plate kit is an option.

Associated has designed a new shock whose shaft goes all the way through the top cap. This means there is no spring effect as the shock goes into bump. No air need be inside. The internal volume remains constant as one end of the shaft enters the other end leaves the internal cavity. One single shock can thus be used on the pod to control roll in both directions. The car has tiny tweak springs as well that bear on the sides of the pod to tweak the car out. This is similar to the CRC solution on the GenX10. The shaft of the center shock also has the ability to twist in an out of the rear cup to adjust droop without shock dissasembly. That is a nice touch as well.

The front suspension has been modified. This means it is not backwards compatible to older cars. You will note the servo is mounted flat. I assumed the steering arms are slightly raised to compensate and still give good bumps steer. The graphite plate that joins the two steering blocks is a stiffener. It may have other functions such as track length adjustment. I can't tell from the photos I have seen. It is different than the old suspension in that it has an aluminum upright which the rest of the suspension bolts to. It is the same in that it is a strut type of suspension. I long for a dampened, lightweight, compact, twin unequal length A-arm front suspension on one of these cars that would be bacwards compatible. I think it would be a hot seller as a replacement. (One company left to present an offering; I have heard news they found a good subcontractor with modern CNC routing equipment)

The car is not very lipo compatible, but one could be mounted on one side and all the electronics mounted on the other. LiPo saddle packs could also be used.

John
Attached Thumbnails
CRC Battle Axe, GenXPro 10, 1/10th pan, Brushless, Lipo,4c, Road, Oval,TipsandTricks-10r5.jpg  

Last edited by John Stranahan; 06-29-2008 at 11:49 AM.
John Stranahan is offline   Reply With Quote
Old 06-28-2008, 02:25 PM   #145
Tech Apprentice
 
Join Date: Feb 2007
Location: Ontario, Canada
Posts: 59
Default RC10R5 rear shock

What's your thoughts on the small 1/12 size rear shock used on the RC10R5? Do you think it will fade or change damping due to the larger mass it now has to handle? CRC must have had a reason to use a 1/10 TC sized shock on the Gen10X. The longer rear links on the RC10R5 should help better control the rear pod although I likely wouldn't notice the difference. It will need less play to allow rotation. The adjustable ball cups on the links may cause grief to some when they're overtightened and lock up the pivoting.

The steering links are much longer than a 1/12 so bumpsteer may be an issue unless you get the front swingarm length close. The CEFX 1/12 use a tall ball stud at the wheel for use with a flat servo to get an upward angled steering link.


Etienne
Tuner EM is offline   Reply With Quote
Old 06-28-2008, 08:10 PM   #146
Tech Elite
 
Join Date: Aug 2002
Location: Houston, Texas
Posts: 3,777
Trader Rating: 27 (100%+)
Send a message via AIM to John Stranahan
Default

Etienne-I have to think that the main venue for these World GT class pans (4 cell, 13.5 brushless), would be on indoor carpet tracks. That being the case that center shock may survive. I know that my experience with center shocks on our large outdoor track is that they take quite a beating. It does not take long for the inner teflon coating to be scraped off and be part of the shock oil. The center shock oil is always black and nasty compared to any other application. It has to do with the imperfectly straight stroke and the fact we are using one shock to do the job of two. This is full mod 6 cell though on a bumpy track. It may be less of a problem when down motored like these are intended to be used. This associated shock is all new. It may be bigger than the small 1/12 sized side shocks. The shaft certainly looks a bit bigger.

Yes that Losi JRXS center shock is holding up very well on the Battle Axe. Very smooth.

I would like to have the car in my hand to see if that servo mounted flat is actually taking care of bump steer. I will note that mid in the Pantoura thread we mounted our servos flat for a test. It required quite a tall ball stud on the steering arm to cure bump steer. So tall that steering arm flex became a problem and steering precision suffered. Or you lived with the bump steer. We tilted our servos back up. Now if Associated has molded a steering arm with the arm exiting the kingpin up high this would be a solution without a super tall ballstud or spacer.

Sadly the World GT class rules require a sliding kingpin strut type of front suspension. How clever of them to stiffle innovation with the rules. Fortunately you don't have to accept them at your venue. You can use the old pan car rules still used at most places that race pan cars. I still want to see a more modern backwards compatible front end come out for these pans. We deserve it. One company left.
I have several examples of more modern front ends. First 3 pics are my examples. All five will prevent blowovers on the long outdoor track and on the velodrome. The suspensions in photo 1 and 3 that duplicate the suspension pick up points and arm lengths give surprizingly better performance from more precise and more abundant steering even on the oval.
John
Attached Thumbnails
CRC Battle Axe, GenXPro 10, 1/10th pan, Brushless, Lipo,4c, Road, Oval,TipsandTricks-dual-arm-front-end-h-002-resized.jpg   CRC Battle Axe, GenXPro 10, 1/10th pan, Brushless, Lipo,4c, Road, Oval,TipsandTricks-front-suspesion-abs-supports-finished-resized.jpg   CRC Battle Axe, GenXPro 10, 1/10th pan, Brushless, Lipo,4c, Road, Oval,TipsandTricks-front-suspension-finished-resized.jpg   CRC Battle Axe, GenXPro 10, 1/10th pan, Brushless, Lipo,4c, Road, Oval,TipsandTricks-1-10-independent-front-pan-front-resized.jpg   CRC Battle Axe, GenXPro 10, 1/10th pan, Brushless, Lipo,4c, Road, Oval,TipsandTricks-mlp-front-end-gt2.jpg  


Last edited by John Stranahan; 07-01-2008 at 07:57 PM.
John Stranahan is offline   Reply With Quote
Old 06-29-2008, 04:57 AM   #147
Tech Lord
 
protc3's Avatar
 
Join Date: Jun 2003
Location: Spring Hill,Florida
Posts: 10,838
Trader Rating: 13 (100%+)
Default

I didnt pay much attention to that in the pics. Wow, im surprised they didnt just use the shock from the TC. I didnt realize anyone was using 1/12th shocks on the 1/10th pan cars.
__________________
Jason Breiner
BMI Racing
Team Associated
J Concepts
protc3 is offline   Reply With Quote
Old 06-29-2008, 04:32 PM   #148
Tech Master
 
espresso1967's Avatar
 
Join Date: Mar 2008
Location: Los Angeles
Posts: 1,102
Trader Rating: 18 (100%+)
Default

Hi John,
Two things that have happened to me while I have been building my crc gen x 10 kit. The first one was last week when I accidently broke the dual axle stem. I was tightening the nut to put the front wheel on and either I may have angled my wrench or what but broke off. Crc is sending me one free of charge. Second while I am waiting for that part I sat down and looked over my kit and took the rear diff apart to add the kimbrough covers to the spur and thank goodness that I did as some how the 1/4 x 3/8 flanged bearing was broken in pieces? Yikes must have been when I was tightening the nylon diff nut? Has this ever happened to you?

There is a third problem I encountered and that was to big of a spur and could not find a small pinion so went with a 75t 48p spur with a 31t, 32, 33 and 34t pinions for testing. Man after having this kit for a month I am now really eager to run some test runs.

John thanks for all the info you have provided in this forum, all very helpful.
__________________
www.cityofangelstshirts.com
espresso1967 is offline   Reply With Quote
Old 06-29-2008, 06:55 PM   #149
Tech Elite
 
Join Date: Aug 2002
Location: Houston, Texas
Posts: 3,777
Trader Rating: 27 (100%+)
Send a message via AIM to John Stranahan
Default

Thanks for the posts guys.

Expresso1967-well I did write you a little discreet blurb on your axle end. It is hidden up above. I have never broken an interior diff bearing. I can imagine it, if the flange is put in the wrong place. On the GenX10 it goes like this. Inner axle diff flange and ring. Next a flangeless bearing to center the spur, next a flanged bearing with flange inward. This is probably the bearing that broke. Easy on that nylon nut as it has the ability to pull the threaded shaft out of the axle on some axles. Tighten only enough for good diff action. Hold left wheel and spur. The right wheel should be hard to turn. Just normal things happening to you. You can never get it quite right on first try. Later with some experience things on a pan become very simple.
John

Last edited by John Stranahan; 07-24-2008 at 12:58 PM.
John Stranahan is offline   Reply With Quote
Old 07-01-2008, 04:32 AM   #150
Tech Master
R/C Tech Elite Subscriber
 
Join Date: Jul 2007
Location: Mooresville, NC
Posts: 1,187
Trader Rating: 21 (100%+)
Default email

John ... you have a regular email

Rick
__________________
Rick "Blue" Sieboldt - Mooresville, NC
* Associated T5M * Tekin * TQ Wire *
www.tqracing.com/rc_products.htm For all your wire needs
lidebt2 is offline   Reply With Quote
Reply

Similar Threads
Thread Thread Starter Forum Replies Last Post
CRC Battle Axe, GenXPro 10, 1/10th pan, Brushless, Lipo,4c, Road, Oval,TipsandTricks John Stranahan Oval, Larger Scales and More 0 05-25-2008 11:48 AM
Electric 10th scale sell-off (T4 team, Sphere, Transponder, LiPo, Brushless...) floatch R/C Items: For Sale/Trade 27 03-14-2008 04:37 AM
Battle Brushless Sensorless Mamba Max : Trinity N80 VS CM 36 moumerico Electric Off-Road 3 04-12-2007 03:18 PM
Battle of the EPs (On or Off Road)! marzin Singapore R/C Racers 4 09-22-2005 09:27 PM



Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are Off



All times are GMT -7. It is currently 02:29 PM.


Powered By: vBulletin v3.9.2.1
Privacy Policy | Terms of Use | Advertise Content © 2001-2011 RCTech.net