S4 weight distribution

[SHY]

Does anyone know how the S4's weight distribution compares to the Durango (or Aero)? Any CAD simulations made?

And how is the S4's weight distribution compared to the BJ4?

Furthermore: is the S4 as good at the XX-4 over rough terrain?

(if no, it's possible to simply measure the tyre loads on digital scales front & rear)

Also some comments on the COG would be nice...

[BenG]

I think the S4 is slimmer than the Bj4 WE, and also more compact, everything is closer to the center line, so the weight distro is aligned lcentrally.

[SHY]

Agree, must be ideal. The S4 looks at it also has the weight more centrally placed than the BJ4, but not as much as the Durango though.

Btw where did you get those rear shock covers on your proto from? Part no. and link to webshop?

[BenG]

Originally Posted by SHY

Agree, must be ideal. The S4 looks at it also has the weight more centrally placed than the BJ4, but not as much as the Durango though.

Btw where did you get those rear shock covers on your proto from? Part no. and link to webshop?

I sold them through my online store. PM me for me more details, as I still have some left over. I have them for the B4, T4, GT2, GT, and also the Revo and Jato.

[jcb]

The weight on the S4 is more central both width ways and length ways compared to the BJ4worlds. From my experiance it results in quicker direction change and allows you to carry more corner speed without the car pushing wide.

Having not driven a XX4 I can't comment on the bump handling but seeing them race together I can say that there is very little to choose between the two.

I can try and get a front and rear weight balance later this evening, at a guess I would say around 60/40 rear to front.

[SHY]

@jcb: excellent! Look forward to knowing more!

The "secret" of the XX-4 is that the fact that the weight is more forward? (compared to BJ4 for instance)

Atomic really makes good stuff, that S4 carbon tub is a piece of work Would they consider selling a complete car?

How do you view the Aero compared to the S4? Has Atomic btw considered the same battery layout? (can't get any more centered than that)

With a low & centered mass it should roll less yes. Is it also less prone to flipping over then?

[Body Paint]

I'll answer what I can SHY.

The weight in the S4 is further forward than the BJ4WE.

And I would think further back than the A-ONE, although as no-one has seen a production Aero and have no real idea what the parts will be made from my summation is pure guess work.

The 3+3 battery config was considered, but in the opinion of all concerened in the decision making the disadvantages outway the advantages. 3+3 moves weight further forward and forces the need to move the centre driveshaft and slipper/spur higher to go over the cells making the CoG higher and raising up the rotating mass.

The XX4 handles bumps in a similar way to the S4, though I find my S4 is more predictable across high speed bumps than my XX4 was.

Yes' we do find the S4 more difficult to grip roll, in fact I find I can run mine higher than I would have run my X5 without having to worry about it falling over.

[jcb]

Shy, so many questions you are not living up to your name

You best bet regarding a full car is speak to my boss, Jonathan Clark who I believe is Old Timer on this forum. Failing that log on to the Atomic Carbon website at http://atomic-carbon.gforceimages.net/ where there is futher contact information.

I don't know a lot about the Aero, apart from it winning the first National, so no comment on that one. Chris Doughty wasn't that far behind with his S4 finishing 2nd.
Like wise with the battery positioning, the advantage of running them 4x2 is that the centre shaft can run from the spur gear to the gear box completly straight making it more efficient compared to the bend in the Aero's. I would think you also have to remove the centre shaft on the Aero to get the cells out where as the S4 batteries can be simple lifted out.

Because the weight is more central I have found that when the car roles over it is more likely to land back on it's wheels. It's not a slice a bread that always lands butter side down

[SHY]

Excellent answers guys, much appreaciated!

"SHY" is just the initials in my name, there are girls that have given the same comment in the past

I'll stick with the X-5 and XX-4 this season, since it's well underway. But I will for sure consider the S4 or Aero next year. I have faith in Atomic Carbon being professional (like JC and X-Factory). But I must admit I find the Durango/Aero layout slightly more appealing (Durango being impossible to get hold of I presume). Here in Norway there's nothing close to "blue groove" and with b/l performance is not a problem, so I'm not worried about the shaft being slightly angled.

http://www.rc10.de/Durango/v3/eng/im...ngo_may_05.pdf
-here's an article about the Durango, at the end you see how you change batteries. Bit of a hassle but not more than 2-3 minutes work.

BUT: placing a GTB or similar...impossible? How does the S4 accomodate our new beasts?

[OldTimer]

The guys above have done most of the work for me thanks guys.

I decided to run 4+2 as i can run a lot lower C of G, what you cannot see from the photos of the S4 is the chassis is milled so the centre slipper / motor mount is as low as you can get it in the chassis. Remember that a motor is 177grams or over 10% of the total weight of the car so i feel its important to get it low.

Also on a early prototype slim4 i had a 4+4 cell layout to test weight distribution further which was interesting

The S4 shell was designed to accept brushless speedos with fans on top, Chris runs the TC spec LRP and this fits easily in the S4.

Now back to Solidworks and work on the S2.

[SHY]

Thx, you're doing a great job!

So to sum up: the S4 has a lower COG than the Aero, but a wee bit wider? What about balance front/rear? And is it perfectly balanced right/left? I'm sure you've tested all kinds of constellations in SolidWorks...

Will you be able to sell a complete S4 kit (with Losi shocks please)? Any idea as to price? ETA?

I think it would interest more buyers if so. Otherwise you have to buy a BJ4, which is already a customized B4. Then an S4 upgrade. I'm sure a lot of BJ4 owners are interested in such a kit, so that's great. But a "full package" would be great!

The shell looks very functional. And with a nice paintjob any shell looks good! Now, when are we gonna see the first shell that is prepared for mounting a fan into it? How cool & functional wouldn't that be?

[OldTimer]

Not sure if the S4 C of G is lower than the Aero as i have only seen the aero from a few feet away and not had it in my hands but i am guessing the aero c of g will change as Lee's car has a milled aluminium chassis and other aluminium parts, were as the production car i understand will have a graphite/plastic moulded chassis and parts.

There is 10 grams difference in weight from right to left, and front to rear is interesting but i don't want to give everything away lol.

If you are looking for a complete car drop me a email

[jcb]

Originally Posted by OldTimer

There is 10 grams difference in weight from right to left, and front to rear is interesting but i don't want to give everything away lol.

I'd just worked out the front to rear distribution on mum's kitchen scales, will keep it to myself for the time being. SHY seems too interested in the Durango / Aero too so maybe best not to tell him everything

[SHY]

ROTFLMAO! Thx & good night guys!

[Body Paint]

Funny you should say that We are looking at motor cooling for brushed initially as our rules state that no part of the speed cotroller can protrude through the bodyshell. How about EFRA rules?

We just need to clarify some rules with the BRCA first.

Originally Posted by SHY

The shell looks very functional. And with a nice paintjob any shell looks good! Now, when are we gonna see the first shell that is prepared for mounting a fan into it? How cool & functional wouldn't that be?

[m2d]

Originally Posted by OldTimer

Now back to Solidworks .

You work whith solidworks ? version 2004 ?

[SHY]

Craig, if the rules are in the way - then try to change them. I've changed some EFRA rules over the years (1:8 TR), it's not that hard if you just formulate it well and supply good arguments. Some lobbying before the AGM is also a big advantage. Let me know if there's anything I can do to help. This is motorsport at a high level and evolution is part of the game.

I presume you basically run by EFRA rules in the UK as well? (so maybe better to change the EFRA rule, then it will automatically apply to BRCA as well)

I think approx. 1st August is the deadline for proposals.

What you are saying is that if you define it to be a "motor cooling device" it is allowed to protrude? But if it's "flush inside" the shell then?

Ahhh... I can smell F1 here! Two small fans in the front, and shark gill vents in the rear...