ferrarimk13

did you think about offering a carbon fiber version, like a pro or something? that would be cool, and would drop the weight, right? what speed are you getting with the motor you're using?

color0

I have designed it already, but it won't be available immediately because of the cost. The whole point of MRCG is to maximize the price/performance ratio, and the extra cost of carbon fiber doesn't really justifiy its marginal stiffness and weight advantage over G10. If there is enough interest, however, I'll make a few, with a 1.5mm lower ride height than a normal MRCG and optimized for RCP, Ozite, etc. competition.

color0

Can't believe another month has already passed, but at least I've got more updates.



I've been testing this first car like mad and trying to find out what works and what doesn't; I put the car through 24 hours of testing at home on a slippery uneven floor to hopefully expose the chassis' weaknesses. Aside from a bit of understeer (which I unwisely tried to counter by drifting), I'd say it's pretty good. It's definitely more stable than the last MR02 I've driven on this floor and has a little bit more corner speed as far as my gut feeling goes. Can't put the power down because the surface is waxed, but still...

http://www.youtube.com/watch?v=vrikpi78MPI

Then after that I took it to the tennis court, drove over 2"x1" ruts (2" wide, 1" deep!) in the concrete, I could hear the chassis smack the ground, but nothing broke or loosened up. That's one thing I would not recommend trying with any chassis, but testing is testing, and the MRCG-RM passed with flying colors. Even with the batteries pushed full forward, the car has massive grip. I was still using medium-compound GRP foams front and rear so it should've spun like a top, but all I got was a moderate degree of understeer and a little slide if you brake too hard and wrench the wheel. I'm more than happy with the results, it's easy to tune out understeer but often not as easy to tune out oversteer.

Cleaning is about the same time-wise as your average MR02. For those concerned about electronics: I didn't have any glitching issues despite all the dust on that board, but you may want to seal/heatshrink/case electronics if you drive in more rigorous environments. Indoor cars will have no issues.



I've also been working on the MM production car, of course, and the G10 chassis parts are already done:



There are a couple new features on the production car that this picture hints at, but I can't explain them until the press release, so nyah...

And I'm just working on the production motor mounts (Delrin rear axle bearing carriers are done, just need to change some settings to make it easier to slip the bearings in). My apologies for the picture quality, but it's tough to lean into the enclosure while trying to hold a steady hand, lol...



Anyways, we're pretty close to release and you can rest assured that the pictures and news will be everywhere when that happens.

jtnktz

My Feedback: (4)

Wow. That looks pretty cool. Will these come RTR? If so how much for just a standard one?

color0

I don't intend to put together any RTR's so that possibility will rest in whether or not I can secure a retailer to help me out. I imagine the most basic RTR could use full Micro-T electronics and a stock Mini-Z motor, nothing particularly expensive.

To tide this thing over until my final exams are done, here's the latest render straight out of the manual:



Special features include infinitely-adjustable suspension stiffness (yes, infinite ), quick-release battery strap, Delrin everything in the rear pod, and a new motor mount that doesn't need drilled cans.

I haven't come up with a good enough servo saver so you'll need a servo saver intended for 1/18.

With a Ti-shaft ball diff and the small electronics (the new ASF board is just one possibility) the MRCG should weigh around 135g without body; that's 5-10g less than a similarly equipped MR02, not too bad.

color0

takman111

Looks cool. I'm just a casual RC guy so I buy all kinds of RCs more for the technology and modding fun than actually running them. I noticed the CAD, you using Solidworks? Best of luck on your venture, the RC community needs more innovators like you.

color0

A long-deserved update.

All our testing has indicated to me that chassis with rear suspension like the MRCG/Sinister/etc. need a lot of rear droop to function properly, but all iterations of this design so far (except the Mini-Z F1) have to raise the roll center excessively to get enough droop.

I decided to take a hint from the F1 and simply cut out the chassis to allow the flex plates to move freely up and down. Sorry for the picture quality, it's late at night and my camera's bordering on 6 years old.









I know the pics are messy and poor in general, so a render should clarify what exactly has changed:



In addition to the flex plates now being completely free to move, they also sit right on top of the chassis for a lower roll center and slightly improved traction. The battery pack has been turned around; while I didn't like this at first (can't adjust weight distribution anymore), it does prevent the motor magnets from attracting to the batts and messing up the rear suspension action. It also left some space for me to move the standoffs inboard to mount the disk damper post and body mounts more securely.

I actually have a new 2.4GHz conversion board on hand to install into the car but I just really wanted to drive this thing. That said, I think it definitely drives better than the last car. I didn't do any rigorous scientific testing, nor has the RCP track arrived yet for that purpose, but the new car drives better on the prepared concrete track. It has much more steering yet handles off-throttle cornering much more tamely. I'll conduct a scientific test with the McLaren shell and GRP tires again to see how much improvement actually came about, but right now it's time to solder in the 2.4GHz board.

PS. If you notice this chassis bearing some similarities to a 1/12 link car, you might be interested to know that there actually is enough space now to turn it into one. I can't say I'm not tempted to experiment with this a bit.

color0

I went to Inside Line Racing for testing yesterday. Awesome place to go if you're in the South Bay Area btw, very clean facility and a well-stocked shop.





I had some trouble with the 2.4GHz ASF system not going into reverse very easily, but besides that, this chassis is pretty quick. Since the car is only a couple days fresh of the CNC machine, I stuck with a very understeer-biased setup that made the car pretty easy to throw around the corners -- not that I intended to, but with the amount of torque my 32t handwound motor puts out, it was a safe decision. Anyways, the setup.

Front:
PN 8deg slicks (+3 offset 8.5mm width rims) ~24mm dia.
Atomic RCP yellow springs (note: the car understeered a heck of a lot, I will be switching out to something significantly softer.)
0 toe
1.5deg camber
4deg caster
lowered 1.5mm

Rear:
PN 6deg slicks (+3 offset 11mm width rims) ~24mm dia.
Kyosho oil damper with RM spring, 3mm preload
Disk damper: soft top spring, medium bottom spring, thin coat of 200wt oil
Kyosho ball diff

Motor:
Top Secret 32t armature in Atomic M1 can
10/53 gearing

There are some pluses and minuses. The PN tires are nice and tacky at first but seem to collect dust proficiently as well, so the car's overall grip suffered a little bit. Transitions are fast though, I noticed the MRCG could really swing through the chicane at Inside Line's new layout, and I could put down the hammer pretty easily afterwards. Judging by the fact that the motor wasn't even warm, though, I should probably have geared up to an 11t pinion. The speed at 10t was right but I just had too much torque to play with in the infield, which is a mixed blessing in open class.

By the end of the day I found myself very ready to go to softer front springs as on-power steering was suffering a little bit. Off-power steering I could get by sharply lifting off the throttle and throwing the car into a drift, and while that was very fun I'll be sure to setup the car correctly for the next testing session.

Thus, softer front springs are in order, and probably softer disk damper too to make the rear end a little bit more responsive. I could probably afford to stiffen the rear spring a little more as well, because this car can afford the traction.

A word on the 2.4GHz system... I didn't have any shutdown issues, but I had some problem areas on the track where the steering would be very imprecise, sometimes sending me into the wall. Same goes for the throttle but this wasn't as noticeable. And no matter what I did with the trims, I had to pause a full second to get the car to reverse. That's pretty bad, I'd have to somehow not make any mistakes if I want to use the ASF board successfully in a race (and that's not going to happen anytime soon, lol...).

Also, reinforcing the front of the body with a tubeful of plastic cement really helps keep it from cracking in the front clip area. Before I glued the front end I saw stress marks in the front clip area just from knocking the walls a few times. Today I went into the walls at nearly full speed (refer to my comment on 2.4GHz steering) and the body remained undamaged. Just dirty, dusty, and with some tire marks on the front when someone else ran me over in a big pile-up.



Anyways, I think I kept up with most of the other MR02's on the track. This new chassis is a significant improvement since the original concept, and I'm thankful for that... really can't ask for much more when trying so many new things (chassis, electronics, body, wheels/tires) at once.

RUNNINONMT

I WAS JUST WONDERING IF ITS AVAILABLE YET?