Here are the raw specs for the Fantom Dyno aluminum flywheel:

Mass: 79g
Radius: 34.75mm
Thickness: 8mm

4 Holes:
Diameter: 6.28mm
Center of hole to center of disk: 30.86mm

Your number was very close. I came up with 46909 gm-mm2. The calculations are attached if you want to repeat them for the steel.

If you want so read some very interesting results of Shock Dyno Testing check out this thread on the Electric Offroad Forum.

http://www.rctech.net/forum/electric...t-results.html

Scott has built and been testing shocks for a couple months now and has published his results. He has also been generous enough to share all his results with me. That means, yes you guessed it there will be a RC Shock Simulator coming to a computer near you soon. I have a very crude version up and running and the correlation between test data and the simulation is very good so far.

Thanks for sharing, would be great to have shock dynamics in software as well.

(strange, but I couldn't post in this thread before, will see if this goes through)

Thought I would share a couple screen shots of the correlation achieved so far between Scott's Test Results and the Simulation. These are the Force vs Displacement and Force vs Velocity graphs which are the normal outputs of a shock dyno.

You mean we would input oil viscosity and piston hole data and you would give back those two graphs along with Damping Coefficient? That might be useful when changing different pistons/oil combinations. As RC shock is very simple and as study showed Force vs Velocity line is just straight line, it almost sounds like all that is needed is Damping Coefficient and that tells most of how shock behaves.

What would be super cool, but probably too difficult to do, would be to simulate car going over bumps/turns/jumps and visually show how suspension is moving and how car is moving. Could give some summary of how much CG of car is moving and how long tires where in contact with ground during course.

Now that I see may messages going through, I'll repost couple questions I had.

Wanted to say this is great software and great videos, helped me to understand suspension much better! I'm trying tune TLR 22-4 buggy (great you had it in your database) for carpet racing with mini pin tyres. So, I'm trying to stiffen it up as much as possible while keeping weight balance.

1) I was wandering - shouldn't droop affect weight balance? I don't think it does currently. As it is now, to decrease roll stiffness it is tempting to decrease droop as much as possible. But I guess there should be some downside for decreasing it. (inside wheel lifting up sooner and more weight on outside wheel?)

2) how ride height affects roll sensitivity? For TLR 22-4, when I increase ride height (let say from 18 to 20mm), roll sensitivity decreases slightly? That's counter intuitive, why would that happen?

3) if you look at TLR 22-4, even in standard setup that is in database, it is quite a bit pushing. So, I was playing with ways to balance weight transfer while making it also stiffer. To get it really stiff I can go almost to max springs on one end (let say front), and then adjust rear to get balance. I also use sway bars and change shock positions and also link positions to some extent. Can get roll sensitivity all the way down from around 6 to 3, and get it balanced in weight transfer page, but Front/rear roll couple is out of balance, around 40 or 35%. If I try to get it balanced as well, my roll sensitivity goes up to 5 or so. So, how important would you say is "Front/rear roll couple" around 50%? Or as long as weight transfer is balanced, it's ok if couple is not?

4) have you had a chance to measure G on buggy in typical racing? I'd love to do that myself, but haven't got right equipment yet. While playing with some configurations, it's kind of easy to get suspension to bottom out at around 1.6G. So, I was wondering if in on-road conditions you can get max 2-2.4G, then buggy probably should get less and that would mean we could ignore problems that occur above certain Gs, I guess.

5) any suggestions for camber tuning for buggy? Suspension travel is much greater. Also with steering data, for front, outside wheel almost always keeps camber (negative). While on rear, because of huge travel, almost always camber goes a lot in positive (like 5 degrees). It almost feels like there is no point in paying attention to camber, more just to weight transfer. Could that be right?

6) as tires are bigger and rounder than on-road, I thought maybe I could test how different camber angles affect traction. For instance, could put piece of carpet on table, put buggy on it, lock front in mid corner position and try to pull with rope from around CG point and measure how strong I have to pull for different camber angles. Would you say this would be valid test? Another idea I had - could put some carpet on floor and drive circles with some certain diameter and try to clock how fast I can do them with different caber angles?

How the shock model is currently setup you enter all the shock dimensions and then you can change number and size of piston holes, piston clearance, oil viscosity, temperature and basically anything else. Right now the model is setup for bladder shocks. next I will work on the emulsion type.

If you are talking about static weight balance then no droop doesnot have an effect. If you are talking about weight transfer balance then yes droop does come into effect once the suspension reaches the droop limit. This effect is modelled in the dynamic simulation.

Changing ride height changes the roll centre position, which changes the roll moment on the chassis.

First off I wouldn't go with a stiff setup. Unlike some things stiffer is not always better. A stiffly sprung car/buggy will be very difficult to drive. You want to go with the softest setup you can without bottoming out the chassis. You need to factor in what the car is doing on track and then use the weight transfer and camber/camber gain to dial in the handling. Weight transfer is only part of the puzzle. Static camber and camber gain also have a huge effect.

Funny you should ask this question. I'm going to my first ever offroad race on Sunday and have xyz accelerometer installed in the car so I should be able to answer this question soon. I have been suggesting to use lower lateral g levels when looking at offroad. The 1g range is a good start.

Don't really have an answer that question. Most buggy tires have a rounded profile and very soft sidewalls. I would watch my tires and if I'm wearing out the outside edge then add more static camber or camber gain or both.

I would think the skid pad test would be the most useful.

I'm reporting back after setting up three cars based on information provided in RC Crew Chief. At the track yesterday, all three cars were easier to drive and I got more laps with each, compared to all previous times at the track with those cars.

I looked at that site and the shock dyno data. I wanted to interject what I think I would like to see as a user of RC Crew Chief.

The issue I face is trying to find a rational combination of damping and spring rate. I was looking around at other software and found some motocross software that looks like it calculated tau and zeta parameters to aid in matching damping oil and shock holes to spring rate. This one looks like it was done with a spreadsheet.

It would be nice to see a graph like that constructed from the RC Crew Chief chassis and mass data that would show the effects of spring rate and oil viscosity and or piston hole changes.

My though was that a simple shock damping model would not help me, but if I could simulate the bounce of the whole system in terms of 'Zeta' I might be able to make a better choice of damping oil. Having the capacity to see how damping affects 'Zeta' seems like this kind of simulation would be doable in RC Crew Chief.

Perhaps this is what you also had in mind.




Reference: http://www.shimrestackor.com/Code/Sa...ing-change.htm

I haven't really thought through how to present the results but that is certainly one method. My goal will be to simplify the presentation as much as possible so it can be easily interpreted by everyone.

Right now I am still working on matching the test data to the model. Rebound results are matching fairly close but high speed bump response is proving to be a challenge.

Hi Bob, i have owned rc crew chief for 12months now brilliant software, i have a question regarding backup, i need to upgrade windows from 7 to 8 and have been advised to format drive is there a way i can backup the rc crew chief program as i have all my database backed up. thanks.

Given the way most Windows programs take advantage of the registry and other shared DLLs, your best bet is to take the database backup you mentioned and restore it to a fresh install of RC3 post-upgrade of Windows.

Erchn is right just use the database backup function on the file menu and save the database file to external storage. Once you have made the switch to Win 8 do a fresh install from the website as before. Your original activation code should work if you have not made any hardware changes. If you need a new activation code just email me and quote your Paypal account email and I will send you a new activation code. Once the program is activated just restore your saved database and all will be good.

Thanks for the encouragement, new release coming soon.