kjoer, I think I know exactly which car you are talking about. I had the exact same experience with it. Great car but you really had to know what you were doing to get it right.

What you are describing brings another concept into the talk besides static weight distribution. What you are seeing is moment of inertia.

A car that has it's mass closer to the cg has a low moment of inertia. It takes less force to rotate the car around its center (just like lighter and/or smaller diameter drivetrain components take less power to accelerate). Usually, this is what we want and is why (I believe) that the change from t-bar cars with saddle packs to link cars with more central, inline packs resulted in a car that could transition more quickly.

Of course, in limited circumstances, spreading the weight out more could result in a slower to respond car that is actually easier to drive. This is rare though and here is why. Yes, the car will be a bit slower to respond and therefore easier to keep it from breaking loose but the moment it does, it will also be slower to recover. So when it does get loose, it will continue to spin around no matter what you do to try and correct it.

Sorry for the long posts guys but I just can't think of any short, simple way to describe these things and they are very important to understand.

First, see my post above where I touch on the subject.

In my opinion, T bar is actually an excellent suspension system for a pan car and yields excellent handling characteristics, especially in sweeping corners. The problem with it is battery location. It forces the batteries (the densest mass in the car) to be placed more outside of the cg location. This results in a higher moment of inertia. A link car with its central location has a lower moment of inertia.

What does this mean on the track? Here are my observations from when I switched from my AMAZING 12L4 to a CRC Gen X:

The 12L4 was always amazing in sweepers. It was very stable on entry to such corners, allowing me to really keep a tight line without having to worry about smacking the inside wall and destroying the car. Its one trouble spot was this one really fast but tight chicane. It would be fine on the quick flip to the right to enter the chicane but the immediate yank of the wheel to the left was sluggish, causing my to miss the apex and forcing me to lift just a bit for the right hand exit. Most of my link car competitors seemed to be taking it flat, tight and were gaining a tenth on me there.

When I took the Gen X there for the first time, it was about the same everywhere on the track except for that chicane. Now I was taking it flat and tight too and my best lap times were a tenth quicker because of it. It was just much quicker to transition.

The only problem was that it was a bit more aggressive entering that sweeper which was making my lap times more inconsistent. It took me a couple of weeks of experimentation to fine tune the set-up and become accustomed to driving it to get the consistency back.

fwiw I think you did a great job describing the forces and effects. The pool cue example was very easy to visualize--and I tend to be visualization-impaired.

Many thanks. I was only poking fun at Michael and Doug for poking fun at my complete, if lengthy, roll-out tutorial a couple years ago.

Thanks, I'm glad you thought so. I too am very visual and I am usually terrible at trying to describe things like this in text. I need to be able to draw graphs and diagrams to get it to make sense. For instance, the tire graph I mentioned of vertical load vs. coefficient of friction. The first time I saw that graph, it made complete sense to me while before it was a complete mystery

I tried to convince a couple guys of how an upper arm change would raise the roll center once and they both insisted that it would lower it. I tried and tried to convince them but they just wouldn't listen. Finally I broke out a piece of paper and diagrammed the whole thing. Two minutes of drawing taught them more than the previous hour of arguing

Hi

What the standard dimentions on a 1/12 scale damper?

i need center-center length on the joints.
diameter/s on a the housing.

Im making CAD drawings of a chassie.

They vary but are you talking about side damper tubes or the center, what we stupid americans would call "shock"?

center damper yes.

sorry i did not explain, im going to draw it only with normal dampers. two standard center shocks will do the trick.

Due to the Halloween, the schedule has been changed.

TQ Pan Car Grand Prix will be held in October 17th Sunday.

Hope it works for everyone

Yeah I like the completely theoretical approach to car physics. Most of us RC guys handle by common knowledge, from trial and error and what others say. There's all kinds of books on (theoretical) car physics, always wanted to read some, never came around to do it. Understanding stuff from the ground up is always good.

Try to find a graph of the friction circle, how much force a tire can "hold" counting both cornering forces and driving forces on the tire.

Hey! my post was only a sentence

And we may tease you about the roll out post, but it is still the definitive statement on the subject, and the one I refer people to when asked about roll out

Another great one. Way back in one of the F1 magazines was an article showing telemetry data from both Michael Schumacher and Mika Hakenen explaining why they thought Michael was the better driver. The crowning graph of the article was a series of friction circles from both drivers showing that Michael kept the little dot pegged to the outside of the circle pretty much all the way from brake zone to exit while Mika's showed some dips during the transition from braking to cornering and again on power corner exit.

Which goes to what I normally see. Moving the weight forward does not always cause less steering. It largely depends on what percentage of the weight is moved forward. Steering will actually increase until you reach that point where the front slips due to the increase in weight before the rear slips due to the loss of weight.

Which is why cars like the Darkside with an in-line battery which moves the overall CG of the car forward sees an increase in steering but in cars with electronics in front of the battery sees a decrease in steering when they move the battery to the forward position. My guess is the in-line car comparatively has moved less of it's weight forward because part of the battery still sits in the rear and the electronics are more rearward as well. Also the center line placement with the old batteries probably played a factor in that as well since more of the mass was closer to the center line. However with today's lighter LiPo batteries this may no longer have the same affect since more of the weight percentage is now in the electronics.

thought i would ask here. can someone please let me know if the crc pro strut front end works on a associated 12r5.1.

also does anyone have an opinion on the crc front end pro brace

thanks in advance

Nope, the CRC front end will fit just about anything else, but the 12R5 has a one-off front end screw spacing. Leave it to Associated to, basically, create a standard that pretty much everybody now follows (front end screw span) and then abandon it themselves.