Johnny Wishbone

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Now if we only raced real cars on carpet or sugar water all things would make more sense.

John St.Amant

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Josh Cyrul

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Brian - 10x stiffer than the difference between the stiffness between the front and rear roll stiffness?? Intersting..... So basically if you run all the same suspension geometry, shock package in the front and rear you can run a chassis that is the same stiffness as the suspension?? 10 x 0 = 0 I believe...

Honestly, I've hear for years "the book says" or "the computer says" but really we are not plugged into the cars like real cars nor have the on-board computers to really record what these cars do (suspension wise, not the motor/speedo data stuff). There's a seperation between man/machine with r/c that you don't find in other motorsport so I think the drivability factor actually has to be higher for us than real motorsport can get away with.

Also, it has a lot to do with the tire dynamics as well. The TC's we can run with rubber with softer set-ups with flexible chassis vs the foam cars that aren't that much stiffer suspension wise (at least in the rear) but we run a way stiffer chassis. Most other people don't like it but I love a 1/12 car with a 3mm chassis and no cut outs. For me, I can feel a huge difference between a 2.5mm and a 3mm chassis.

If I ever have the time...lol... I will make up a system to check this (I've talked about it for a few years now) as I'm sure there's a lot to learn here. BUT, I also am a firm believer that there is no set rule of what you HAVE to do to make a race car fast. I think we've seen that for years where people say you have to do this or that and a year or two the bodies, tires, motors, batteries change and everything that was the rule is now out the window!! Ask the oval community about our CEFX Lithium oval car. I was told I took the Bible of "rules" they all follow and did everything possible to destroy it and my car wouldn't work... Now they are all copying it....

As far as the data and #'s I use to design our cars... Of course I could tell you, but then I'd have to kill you...lol...

Josh Cyrul

iTrader: (1)

Did I mention the fact that you can maintain almost identical chassis stiffness but change the position of the flex (front/rear) and it will make the car drive completely different?? It's not just the overall flex but the positioning and sort of "spring rate" of the flex (linear or progressive). I can't wait to hear about everyone getting the optional "wings" for the Photon to see the responce on how dramatically changing the flex in the front vs the rear is... The overall flex would be the same but the rate and position of it would be different creating a completely different feel from the car.... We all have a ton to learn and it's exciting to move into these area's that makes everyone scratch their heads (including me..lol)...

Goingfast

iTrader: (29)

Hi Josh
next week ,I should getting the med and hard wings for my photon..
Sound how I'm thinking about putting on the Med or hard wings. Do you think it will make the car steer harder ( Same effect like a sway bar in the rear)!
What is the phone Number to TOP racing USA part department?

Josh Cyrul

iTrader: (1)

Goingfast - I have my own idea/opinion on this but I rather hear the comments from everyone trying them without a tained view based on what I have said. I don't have the TOP USA #...lol.. Only EJ's cell...

wingracer

iTrader: (24)

I have to agree that unlike a real race car, our RC cars need some flex. We just don't have that seat of the pants driver control and feedback to get a car set-up and driven perfectly. I bet if you RC'ed a modern F1 car it we be way too responsive and impossible to drive from outside the car. We need a much broader "sweet spot" and flex can give us that. Of course, too much flex can be a bad thing too. Too soft and the car will not respond to suspension changes.

I can think of two cars as examples, both 1/8th onroad though since that's where most of my experience lies.

1. Picco Integra. This car had a lot of flex compared to most other cars at the time. I could go from the hardest to the softest front spring and notice very little change in handling.

2. Serpent Veteq. Very stiff car. I never had one myself but I talked to many drivers who complained about never being able to find the sweet spot. It would go from push to loose with the slightest change.

If you look at the two big dogs today, Kyosho and Mugen, they have gone without braces between the radio plate and the rear end to keep the car flexible but use a pretty stout chassis to limit this flex so the car remains responsive to changes.

Goingfast

iTrader: (29)

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syndr0me

iTrader: (32)

I have a TA05 I drive on carpet sometimes for fun, and even with the carbon-reinforced chassis, it's got quite a bit of flex. I think I could make every shock position and camber link on that car different and it would still feel pretty good on the track. But, it wants to scrub, and there's really not a lot of options for taking more flex out, so it's kind of limited when the traction really comes up.

The Photon also seems to have a lot of flex, but on this car, that doesn't seem to translate to a large setup window. All I can tell at this point is that it's quite a bit different than a traditional sedan. I kind of expect the fast setups to be pretty unorthodox, 'cause the things I've learned about setup to this point aren't really working.

Speaking of flex, is there any concern that the top deck and the wings are of different thicknesses, and therefore might not flex at the same rate, or could introduce some inconsistency? On our high-traction rug the other night, I was really struggling with the car being different lap to lap.

wkl

I am from Asia country. I run the Photon outdoor with rubber tires.
I follow the standard setup from the manual and have try few changes, and the overall feeling is very sensitive and the car is not stable and hard to drive consistently.

Is there any way for me to make the car more stable and the front is less sensitive? btw I am using Sorex 36R tires at my track.

John St.Amant

iTrader: (1)

Add rear toe in.
Remove front toe out.
Reduce front camber.
In that order....

Josh Cyrul

iTrader: (1)

No concern on the thickness differences. We will have different top decks, wings and chassis to tune the flex for the style of racing that the customer is doing so really it doesn't matter. Keep in mind, there is only 9mm bewteen the screw holes on the wings and 154+ between the shortest two screw holes in the top deck.. They aren't going to flex the same reguardless....

wlk - Put the steering crank (verticle ackerman on the set-up sheet) to the shortest position and use a #10 insert. You can also try a #11 which will settle the car down more. Also, if you use the standard steering arm on the servo - be sure to use the short hole/position - If you use the top hole you will have too much leverage from the servo and the steering will be very fast and probably too sensitive.

wkl

My rear toe in is 3 degree
front 0 toe out
camber is -1 degree

I see, I have try the #10 & #11 insert and using the short hole on the standard steering arm.
Josh, how bout anything I can try with camber link, shock position and roll center?

Josh Cyrul

iTrader: (1)

wkl - If you can, post your complete set-up or e-mail it to me - [email protected] - Also, if you can take some pictures of your car (body on as well) that would be great. It's a lot easier to look at a car/set-up and figure out what to do than to spend a day or two guessing about what is the problem. One suggestion - if you do have a spacer in front of the front suspension mount (front a-arm sweep) then please take it out. This can make the car twitchy and hard to drive. You can also try raising the inner ball stud on the camber links (front and rear), shorte the front camber link and a longer rear camber link. All of these should settle the car down.

Brian McGreevy

iTrader: (10)

Yes, that would be correct if we were only concerned with roll, since you would have zero torsional moment across the chassis. However we're not just concerned with roll, we need to account for dive, squat and combinations of these with roll. Also, to provide optimum handling, even with a car with 50/50 weight bias, you almost always have differing roll stiffnesses due to the fact that the front tires see different slip angles than the rears, and under weight transfer the weight bias changes and cause the tires to provide more or less grip.

You're definitely right. We rely on "by feel" and qualitative data far more than in most motorsports. The biggest thing we are limited by is the tires. If we were able to have reasonable tire data (i.e. lateral and longitudinal force vs. slip angle, normal force, camber angle and combinations of these), we could use kinematic modeling to design cars that made the most use of these tires. The problem is, we need to have cars that are adaptable to many tires and many tracks, which make the tires work differently.


Yep things do change so fast, which is why cars have to be so adaptable. Trust me I know all about not having to conform to make a car go fast. I designed and built the suspension for our Formula SAE race car, and if you know anything about that you'll know that it's the type of race car that has the most engineering freedom out there.

I was only curious about the #'s...I was just hoping you had them because I often doubt that many manufacturers do. Kill me...haha well you could try