Xray T4 '13

Old 10-02-2012, 02:57 AM
  #271  
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Originally Posted by Skiddins View Post
No, you don't, but people still buy them.

I do have the ECS driveshafts already and I'm currently trying the graphite arms.
None of these things is essential, they are 'tuning options'
If you didnt need them, why do you have them?
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Old 10-02-2012, 03:06 AM
  #272  
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Originally Posted by Skiddins View Post
If it is as simple as that, why doesn't everyone just raise their roll center's right up so the car doesn't roll at all in the corners?
Because preventing body-roll doesn't prevent weight transfer. The only things that have any significant effect on the total weight transferred are the CoG, the track width (for cornering), the wheelbase (for acceleration/braking) and the speed you're going. This is why all racing cars run as low a CoG as possible and as wide as possible within the regulations. Wheelbase has to be comprimised because going too long has other downsides.

Everything else just changes how/when/where the weight is transferred (either at the front or rear of the car, and either via the springs/dampers or via the links themselves).

I know it goes against a lot of the made-up stuff posted on here, but it's true nonetheless.
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Old 10-02-2012, 04:16 AM
  #273  
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Originally Posted by Reese Bobby View Post
If you didnt need them, why do you have them?
To try them in various conditions and on different tracks.

The graphite arms make the car very twitchy on carpet so it can be very difficult to drive.

The ECS driveshafts are great at preventing the vibration from full lock with a spool, but a lot of people still use the standard driveshafts as the extra drag can help pitch the car into a corner, again, it depends on the track, the type and number of corners etc.

Steel outdrives sound great, and are less likely to break, but they transmit the damage to the driveshafts instead and bend them.

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Old 10-02-2012, 04:55 AM
  #274  
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Some people go way to deep and subsequently mind f**k themselves out of all proportion.
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Old 10-02-2012, 06:06 AM
  #275  
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Originally Posted by daleburr View Post

I know it goes against a lot of the made-up stuff posted on here, but it's true nonetheless.
Dale, I know you are well positioned to talk about this stuff, do you think it all translates directly to RC?

As far as I know race car theory is to make the chassis as stiff as possible to make suspension tuning more effective, but now a lot of RC companies seem to be playing with chassis stiffness as a tuning option. Are full size motorsport outfits designing flex into chassis?

I know myself that when I've played with road car shocks, it's done the exact opposite of what I'm expecting with regard to my RC experience.

Would any of us buy an Impreza or Evo, lock the front diff solid and expect it to "work" on the road, or racetrack?


This isn't a dig, or argument. I'm genuinely interested in why RC cars seem to work completely differently with different theories to full size cars.
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Old 10-02-2012, 06:12 AM
  #276  
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Originally Posted by daleburr View Post
LOL at the made-up physics in this post.

Lower CoG = less weight transfer = more overall grip, due to tyre load curves being non-linear. As you transfer weight to the outside tyre it gains a small amount of grip, but the inside tyre loses a larger amount of grip, so you have less grip overall.

This is why every racing car designer in the world tries as hard as possible to lower the CoG.
Glad you spotted that one Dale. I was going to comment but decided to bite my tongue. Possibly the dumbest bit of bad science to be posted in this forum in 10 years of my membership.
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Old 10-02-2012, 06:36 AM
  #277  
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Originally Posted by cyclonetog View Post
Dale, I know you are well positioned to talk about this stuff, do you think it all translates directly to RC?

As far as I know race car theory is to make the chassis as stiff as possible to make suspension tuning more effective, but now a lot of RC companies seem to be playing with chassis stiffness as a tuning option. Are full size motorsport outfits designing flex into chassis?

I know myself that when I've played with road car shocks, it's done the exact opposite of what I'm expecting with regard to my RC experience.

Would any of us buy an Impreza or Evo, lock the front diff solid and expect it to "work" on the road, or racetrack?


This isn't a dig, or argument. I'm genuinely interested in why RC cars seem to work completely differently with different theories to full size cars.
Chassis flex isn't totally unique to RC, I have heard moto GP teams talking about it, but it does go against traditional race-car design. In real F1 we make the chassis as stiff as possible, but then we have very sophisticated suspension to get the car to roll, pitch and ride bumps/curbs. Our RC cars are quite primative, so chassis flex helps us out.

A flexible chassis allows you to run the shock springs fairly stiff to limit body pitch/roll, but means when you hit a curb or a single-wheel bump, the chassis can flex to absorb it. On our bumpy UK tracks with big curbs this is a massive benefit.

It also seems to give a wider operating window. Not 100% sure why, but I suspect it helps keep the front and rear weight transfer fairly equal while cornering, limiting the impact of the springs/RCs have been chosen.
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Old 10-02-2012, 06:38 AM
  #278  
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Originally Posted by cyclonetog View Post
Dale, I know you are well positioned to talk about this stuff, do you think it all translates directly to RC?

As far as I know race car theory is to make the chassis as stiff as possible to make suspension tuning more effective, but now a lot of RC companies seem to be playing with chassis stiffness as a tuning option. Are full size motorsport outfits designing flex into chassis?

I know myself that when I've played with road car shocks, it's done the exact opposite of what I'm expecting with regard to my RC experience.

Would any of us buy an Impreza or Evo, lock the front diff solid and expect it to "work" on the road, or racetrack?


This isn't a dig, or argument. I'm genuinely interested in why RC cars seem to work completely differently with different theories to full size cars.
Race car designers make their chassis as stiff as possible and to make their bodys roll as little as possible in order to make the suspension and tyres work more efficiently and effectivley. If you have chassis flex or too much body roll it takes something away from your set up, it makes your tyres and suspension work less which means an ill handeling car.
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Old 10-02-2012, 07:24 AM
  #279  
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XRAY T4 introduce by Martin Hudy
Sep 29,2012 @ RC addict , Bangkok, Thailand
during race event Xray Challenge Asia 2012

+ YouTube Video
ERROR: If you can see this, then YouTube is down or you don't have Flash installed.




the man that have a best lucky, he got Xray T4 prototype kit from hand of Martin Hudy

+ YouTube Video
ERROR: If you can see this, then YouTube is down or you don't have Flash installed.
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Old 10-02-2012, 07:24 AM
  #280  
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Originally Posted by daleburr View Post
Chassis flex isn't totally unique to RC, I have heard moto GP teams talking about it, but it does go against traditional race-car design. In real F1 we make the chassis as stiff as possible, but then we have very sophisticated suspension to get the car to roll, pitch and ride bumps/curbs. Our RC cars are quite primative, so chassis flex helps us out.

A flexible chassis allows you to run the shock springs fairly stiff to limit body pitch/roll, but means when you hit a curb or a single-wheel bump, the chassis can flex to absorb it. On our bumpy UK tracks with big curbs this is a massive benefit.

It also seems to give a wider operating window. Not 100% sure why, but I suspect it helps keep the front and rear weight transfer fairly equal while cornering, limiting the impact of the springs/RCs have been chosen.
So it it inconceivable that a lower CG could actually take grip away? (In model cars)

Ive had to move things higher in a pinch at a race meeting and felt the car actually has more grip.
While I agree with your theory on lower CG giving more grip and being a purist I try to keep it that way myself, it doesn't always seem to work.

I have a feeling that the car seems to behave differently because we're observing it from the outside, not feeling it from the inside but I don't really think I have a way to prove that.
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Old 10-02-2012, 08:16 AM
  #281  
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Originally Posted by cyclonetog View Post
So it it inconceivable that a lower CG could actually take grip away? (In model cars)

Ive had to move things higher in a pinch at a race meeting and felt the car actually has more grip.
While I agree with your theory on lower CG giving more grip and being a purist I try to keep it that way myself, it doesn't always seem to work.

I have a feeling that the car seems to behave differently because we're observing it from the outside, not feeling it from the inside but I don't really think I have a way to prove that.
Raising the CoG will create more body roll, which could put the cambers or roll-centres into a position that gives more grip. But it would be better achieved with softer springs or lower roll-centres, as that way you'll get whatever benefit the extra body roll provided, plus less weight transfer from the lower CoG, so more grip.
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Old 10-02-2012, 10:25 AM
  #282  
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dunno if this was ask prior, but just want a confirmation.
can these parts from T3 be used on the new T4?
F/R arms
C-Hub
Steering knuckle
F/R belts
gear diffs
mid pulleys

t-i-a
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Old 10-02-2012, 11:42 AM
  #283  
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Originally Posted by RevMaxx View Post
dunno if this was ask prior, but just want a confirmation.
can these parts from T3 be used on the new T4?
F/R arms
C-Hub
Steering knuckle
F/R belts
gear diffs
mid pulleys

t-i-a
Yep.
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Old 10-02-2012, 12:56 PM
  #284  
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Originally Posted by RevMaxx View Post
dunno if this was ask prior, but just want a confirmation.
can these parts from T3 be used on the new T4?
F/R arms
C-Hub
Steering knuckle
F/R belts
gear diffs
mid pulleys

t-i-a
Yes
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Old 10-02-2012, 12:59 PM
  #285  
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But do R/C tires actually work like real car tires? Or does the grip to load ratio actually improve with more load?

-Mike
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