This guy posted this on youtube and my response might clarify what I'm doing for those of you who may not have read my thread from the beginning.

Posted in the comments on You Tube
Ok, so here is the feedback you are not going to want to hear.
First off, you are not a good or consistent enough driver to truly push a car to the point where you can see/feel real shortcomings. Basically, because you are driving the car wrong, it seems to you that the car is wrong, but it is your driving that is causing some of your issues.
Second, your "aero" work is laughable at best. Off-road rc cars don't travel at high enough speeds for significant gains to be made with aero. Also, aero is all about controlling the air, and most of your "upgrades" do nothing because the air is dirty, and way too low energy to really do anything significant.
RC cars rely almost entirely mechanical grip. You have done a bunch of stuff to remove weight, and centralize mass, but you fail to understand that removing too much weight from the chassis alone throws off the sprung to unsprung weight ratio.
You have the ability to make one off parts because you are a shop teacher. Yet your lack of understanding of vehicle dynamics, and driving ability make for a development path of your "upgrades" which are going to yield very little tangible improvements. Go ahead and find the fastest driver at your track, and have him take a couple laps with your 2wd buggy. I guarantee the good driver is going to think your car is really difficult to drive fast.
You can trust I know what I'm talking about. I have been racing rc cars for 25+ years, and I am a mechanical engineer, with a focus on vehicle dynamics.


My Response
Just wanted to respond to Jules....

I've been racing since 1986 so that's 31 years and a few years ago I qualified 2nd in the open class at the Cactus Classic.

I have run the popular (normal) setups and won many races but I wanted to further my understanding of vehicle design. Plus, what I'm doing is fun.

This was a practice day where I was learning the track. Plus the car is setup for dirt with a 67% weight bias, I was just doing some testing and experimenting.

I am aware of vehicle set-up through years of racing with team drivers and have a growing understanding of vehicle dynamics / engineering through tuning and building other projects.

You seemed to have missed the whole point of this project! The car has been developed to reduce the polar moment of mass on a low grip clay track, not to make the car super light. The weight was just a side effect of the test. And I made changes to geometry to further reduce the polar mass to see if the gain was worth the loss. Thus resulting in my further understanding of ackerman change due to bell crank geometry.

Your comment about offroad aerodynamics not offering significant gains..... Have you ever run a 2wd buggy without a wing? Have you played with cab forward bodies? Front wings being developed by manufactures? Nobody is looking at air management, just downforce. My tests have lead me to start developing some air management in the buggy I am currently building.

Did you take a close look at what I have done with removing the middle of the front shock tower to get more clean air to the front window and the window canards which significantly improved steering at high speed. I am aware that the side pods aren't doing much, but they offer protection for the esc which is moved on the new car I am building due to testing this new idea.

As for the arm covers they do make a difference at high speed. Tested back to back I felt a difference. Yes I am aware that it is dealing with dirty air and that they have sharp angles where the air would delaminate and "stall" reducing the downforce produced. Again I said this is a test and the test yielded significant enough results to warrant further development. I think that what your missing is that it is probably picking up cleanish air down near the tack and picking it up over the arm. I am planning to build a mind tunnel and vacuum former with a couple of students that will allow for better designs.

I am aware that the rear diffuser is doing little to nothing since there is no floor on the car and offroad cars are too high for any ground effect. It was an idea that didn't work but gave me more ideas to test.

Through my testing and experimenting I have found that the front wing is doing little to nothing and have come up with other things I want to test as a result of what I have learned.

As for the correlation of vehicle weight and unsprung weight I am fully aware of the theory and plan to maintain the ratio in the new car I am building.

So in closing I am aware that the car handles poorly..... It was never meant to work on carpet but my new car isn't done yet so I went out to test some stuff. Just like the manufactures do. I was at the Ready race a number of years ago when Gil Losi and Brian Kinwald were testing a prototype of the XXX-S. I found out later from Gil that it was one of the first times out with the car and they were there to develop concept and learn. Sound familiar?

So yes to put an answer to your statement of my lack of knowledge YES I could go faster copying setups from the fast guys. I have done that. I wanted a new challenge and wanted to explore new ideas. And yes I have a ton to learn but I have learned a ton from doing and trying things that didn't work, as an educator I believe that is the best way to learn. Also I don't have all of the time, resources and knowledge to design and build all of my ideas to life to find out that they don't work so I have to take small steps and develop ideas simply over time.

You would have to take a look at my other project and read about what I am trying to do to realise that everything you said is true but you completely missed the purpose of what I am doing. And that I DO know what I am doing! People need to learn to test things trough testing to develop their cars setups and actually learn about vehicle dynamics, aerodynamics etc. and not try to simply re-regurgitate what everyone else is doing.

So thanks for the advice but I'm good.


Enjoy!