R/C Tech Forums

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

Reply
 
Thread Tools Search this Thread
Old 03-14-2013, 12:28 PM   #46
Tech Fanatic
 
glide 1's Avatar
 
Join Date: Feb 2002
Location: Cebu City, Philippines
Posts: 760
Default

Hi wtcc,

Great project you got going here. i look forward to more developments.

I saw the video you posted in youtube and i would like to point out 1 or 2 things:

The way you have the servo horn controlling both front and rear steering - have you tried decreasing the throw (or shorten the rear side of servo horn) of the rear steering link in relation to the front throw? I would think that you would not need as much rear steering/throw than what you have on the video. So if Front steering, for example, is a value of 10 and the rear steering say 3, could you perhaps make it 10 and 2 (or 1) for that matter? I think the "ratio" between front and rear throw is critical, and would determine how "twitchy" or "planted" the car will feel.

This brings me to this - if you decide to go with 1 servo to control both front and rear, then would'nt it be a good idea to perhaps design a servo horn that is adjustable so that you could change the "ratio" of the front /rear steering as mentioned above? Have different holes on the horn itself? or adjustable "sliding" type horn for infinite adjustment?

Of course the 2 servo idea which has already been mentioned in previous posts would solve all this - easier.... The Sanwa Mt-4 has mixing functions that will make it easy to do, you'll just have to design it with 2 servos.

Again, nice work.

Will be following this thread.
glide 1 is offline   Reply With Quote
Old 03-14-2013, 02:45 PM   #47
Tech Master
 
wtcc's Avatar
 
Join Date: Jul 2010
Location: Germany
Posts: 1,304
Trader Rating: 1 (100%+)
Default

Hello glide,

I not sure which servo horn I used in the video, but the actual relation is 8.5mm for the rearsteering servoarm and 25mm for the front steering servoarm. At my last test drive I found this relation as acceptable. The two servo idea will not happen before autumn this year as I already spent a lot of money for the coming summer

Now the pictures of the optimized car:

The servo now has no chance to get moved around or damaged from outside forces. It is fitted really good and would even work without being attached to the bulkhead. Luckily everything worked out as planned













The new shocktower now provide the needed setup holes for the suspension turnbuckles (Damn! I forgot the word again...). So I can use shorter upper arms.





As mentioned some posts before the new servo position is some mm lower which betters the angles for the steering turnbuckles. But it also looks much better as the servo looks like it is one unit with the lipo.







I am sure I didn't mention a lot of things as everything went together very well and surprisingly seems to function as planned so feel free to ask. If I find some time I do some runs on saturday
__________________
/// CAUTION: Rogue robot \\\
wtcc is offline   Reply With Quote
Old 03-23-2013, 12:19 PM   #48
Tech Master
 
wtcc's Avatar
 
Join Date: Jul 2010
Location: Germany
Posts: 1,304
Trader Rating: 1 (100%+)
Default

Yesterday and today I did some testdrives on two different carpet tracks in my region.
The car lasted very good until the third battery of the day when I broke the rear shocktower after a overturning which didn't look that hard...



So I pay for beeing stingy with the cfk. Luckily I can use the older shocktower without the additionally setup holes for the camberlinks after having two hard days with short camberlinks in the rear. The car was twitchy and I couldn't trust it at all. After the change (back) to the longer camberlinks in the rear the character of the car changed for good. I could be harder on the throttle, the rear forgave hard load changes and it felt much better! What also made it better was the change of the shocks. I went back to the standard TC6.1 shocktower and shocks after the accident mentioned above and the car got a little better (when compared with the short Tshox).



That is how the 4WS looked today. I also made some videos which I am uploading right now. Later you will see how it drove when it was twitchy. It was still very good in taking the speed through the corner, but I had to be extra extra nice when stepping on the throttle.
__________________
/// CAUTION: Rogue robot \\\
wtcc is offline   Reply With Quote
Old 03-24-2013, 12:18 PM   #49
Tech Master
 
wtcc's Avatar
 
Join Date: Jul 2010
Location: Germany
Posts: 1,304
Trader Rating: 1 (100%+)
Default

Now the promised video:

http://www.youtube.com/watch?v=zALO06yMVRA

Another one will follow
__________________
/// CAUTION: Rogue robot \\\
wtcc is offline   Reply With Quote
Old 03-24-2013, 02:10 PM   #50
Tech Regular
 
SS LS1's Avatar
 
Join Date: Feb 2004
Location: Michigan
Posts: 360
Trader Rating: 23 (100%+)
Default

In your earlier video of the steering linkage in action it appears you have about 3 of rear toe which is good for rear grip under acceleration. I would however question how it affects the rear steering efficiency. With that much rear toe I would guess the rear steering is lazy initially then would become suddenly aggressive which would cause it to feel twitchy in tight corners possibly causing oversteer after the apex of a corner. Have you tried different rear toe angles (or less rear toe) to see how it changes the feel of the car? Just curious.
__________________
Tamiya 417v7 Sedan, ___ Tamiya 417v7 USGT, ___ CEFEX EVO w/ 417 suspension VTA
Exotex TA06 Pro CS Drifting, ___ Tamiya 417v5 (sold)
AE SC10 4x4
AE SC10 AE B4.11
SS LS1 is offline   Reply With Quote
Old 03-24-2013, 02:46 PM   #51
Tech Master
 
wtcc's Avatar
 
Join Date: Jul 2010
Location: Germany
Posts: 1,304
Trader Rating: 1 (100%+)
Default

You are right!
2.5 rear toe made the car inert in the corner and nervous under load changes. Also the rear wants to step out in fast corners. I changed that some weeks ago to 0.5 per side. This felt much better and the rear seemed to have more grip.
I haven't tried positive toe yet, but I cannot imagine that it will make the car any better...
__________________
/// CAUTION: Rogue robot \\\
wtcc is offline   Reply With Quote
Old 03-24-2013, 02:59 PM   #52
Tech Regular
 
SS LS1's Avatar
 
Join Date: Feb 2004
Location: Michigan
Posts: 360
Trader Rating: 23 (100%+)
Default

Thanks for the reply, cool project! I was just trying to help keep the ideas flowing as others have been also doing. I enjoy watching your progress.
__________________
Tamiya 417v7 Sedan, ___ Tamiya 417v7 USGT, ___ CEFEX EVO w/ 417 suspension VTA
Exotex TA06 Pro CS Drifting, ___ Tamiya 417v5 (sold)
AE SC10 4x4
AE SC10 AE B4.11
SS LS1 is offline   Reply With Quote
Old 03-24-2013, 03:33 PM   #53
Tech Master
 
wtcc's Avatar
 
Join Date: Jul 2010
Location: Germany
Posts: 1,304
Trader Rating: 1 (100%+)
Default

Thank you! I appreciate any constructive thinking

Here is another video. Me against a T4 with my twitchy car. Even though I seem to be faster overall, you can clearly see that I have my hands full with keeping the car on the racing line:

http://www.youtube.com/watch?v=k5Xz4yo8cKc

By the way: I am the blue car. Sorry for the quality... I couldn't upload the video to youtube the normal way because I couln't get it from my Iphone to the pc
__________________
/// CAUTION: Rogue robot \\\
wtcc is offline   Reply With Quote
Old 03-25-2013, 05:01 AM   #54
Suspended
 
Join Date: Aug 2012
Posts: 69
Default

wow, thats so cool. Great engineering and overall idea. I am curious to know how it handles and how well it corners compared to a stock tc6.And obviously the next question would be...: ''is it legal to build nitro cars on your own...??
sid8 is offline   Reply With Quote
Old 04-06-2013, 12:03 PM   #55
Tech Master
 
wtcc's Avatar
 
Join Date: Jul 2010
Location: Germany
Posts: 1,304
Trader Rating: 1 (100%+)
Default

Got my T-shirt and stickers today



Now everybody can't overlook what I drive
__________________
/// CAUTION: Rogue robot \\\
wtcc is offline   Reply With Quote
Old 04-20-2013, 02:17 PM   #56
Tech Master
 
wtcc's Avatar
 
Join Date: Jul 2010
Location: Germany
Posts: 1,304
Trader Rating: 1 (100%+)
Default

The 4WS got his first own body today:









The car will get a Reedy 10.5t Mach2 motor and will be used for our club championship, a blinky class with an 4,7 fdr, 15 minutes race time, free tire choice and no weight limit The 4WS comes at 1200gr. race ready
__________________
/// CAUTION: Rogue robot \\\
wtcc is offline   Reply With Quote
Old 04-20-2013, 04:37 PM   #57
Tech Elite
 
DesertRat's Avatar
R/C Tech Elite Subscriber
 
Join Date: Mar 2011
Location: Sniffin the 'Sauce Fumes
Posts: 2,705
Trader Rating: 2 (100%+)
Default

Do I spy foam tires?
__________________
I race toy cars for fun. If I need to explain, you'll never understand.
Current rides: Diggity DC4 Chassis #10. Losi JRX-S Type R. Losi 22 4.0, CRC Xi (retired), CRC Altered Ego Aluminum Chassis. Associated B4 based dirt oval late model.
WTB: Carpet racing in Arizona.
DesertRat is offline   Reply With Quote
Old 04-21-2013, 04:41 AM   #58
Tech Master
 
wtcc's Avatar
 
Join Date: Jul 2010
Location: Germany
Posts: 1,304
Trader Rating: 1 (100%+)
Default


In Germany we are still around 8C - 12C. I enjoy not to have to prepare rubber tires with additive and tire warmer. Just putting them on the car and drive. I use them in the summer too.

Added some more sticker bling:







__________________
/// CAUTION: Rogue robot \\\
wtcc is offline   Reply With Quote
Old 05-08-2013, 03:10 PM   #59
Tech Master
 
wtcc's Avatar
 
Join Date: Jul 2010
Location: Germany
Posts: 1,304
Trader Rating: 1 (100%+)
Default

In the meantime the sun shined for some days already here in Germany and I used them to drive the 4WS a lot. I really love how the car handles and how much steering it can provide if it is needed.

Unfortunately the 4000 mAh of the battery will not be enough to perform our 15 minute clubrace. This makes me really unhappy, because with the 4WS I constantly lapped around 1-2 tenth faster than with my "normal" TC6.1WC.

Another thing I found out is that the 4WS is really hard to drive on low grip and/or dusty tracks. This problem maybe is not just occuring with the 4WS but with other TCs also, but it feels worse with the 4WS than with a standard TC.

Nevertheless I sometimes wish to have a factory background like Hudy to keep constantly evolving my car(s) and try out my ideas. My first prototype was the KR1. It came with a one-belt-layout, laydown shocks, shorty lipo use, centered motor and a lot of prototype parts that cost a lot of money, for example the symmetrical ultra slim diffs.



Maybe some will remember it (I posted some pictures in the TC9-Thread one year ago).

Since I was unable to overcome my revolutional (or stupid ) drive train issues, I just drove the car three times. Which is a shame for the money I spent on it and the fun I had driving it. So I thought about reusing the parts and ideas and combine them with my 4WS-project. CAD should show if it is possible:



... and it is possible. "Unfortunately" I improved a lot of parts to optimize the areas which didn't work as hoped on the KR1. I now ended up with 19 new parts including chassis, topplate, bulkheads, shock mounts and a lot of small parts. The car has a new aura now and offers new adjustments as well as an option to convert it to a 2-wheel-steering TC with just a few tweaks.



Puuh, bringing this car into reality will be expensive even though it is just about some aluminium and cfk parts. Would be great to have sponsor Somebody interested in a ultra low cog, centered weight, shorty lipo, lay down shock, four wheel steering TC with easy parts availability ?
__________________
/// CAUTION: Rogue robot \\\
wtcc is offline   Reply With Quote
Old 05-08-2013, 05:40 PM   #60
Tech Elite
 
mkiiina's Avatar
 
Join Date: Jul 2007
Location: Frisco TX
Posts: 2,334
Trader Rating: 69 (100%+)
Default

Very cool project man! Its neat to see the full evolution from concept to finished product.
mkiiina is offline   Reply With Quote
Reply



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 07:27 PM.


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