144.93 mph e-revo?? - RC-Monster Forums

**144.93 mph e-revo?? -** 03.25.2007, 06:23 PM

Ok so I got bored and decided to see how fast I could get my E-revo (if I ever get to finish it). With the speed calculator I got 144.93 mph. Numbers are as follows.

F/r diff ratio - 8th scale buggy diff 43/13
Center Diff - 2.2 slipperential
additional - 1
Spur - 34
Pinion - 24
voltage - 24 6s lipo @ 4.00v
Kv - 2700 Neu 1515 1.5d
tire diameter - 5.75
Ballooning - 1.0

So who's willing to find out how much wind resistance there is on an e-revo @ 145mph:018:
I seriously doubt it will ever hit that speed, but it'd be really cool to try. Nevermind the ensueing explosion that'd occur if you wrecked:028:
Just a thought.

skellyo · 03.25.2007, 06:51 PM

Quote:

Originally Posted by celticclown

Ok so I got bored and decided to see how fast I could get my E-revo (if I ever get to finish it). With the speed calculator I got 144.93 mph. Numbers are as follows.

F/r diff ratio - 8th scale buggy diff 43/13
Center Diff - 2.2 slipperential
additional - 1
Spur - 34
Pinion - 24
voltage - 24 6s lipo @ 4.00v
Kv - 2700 Neu 1515 1.5d
tire diameter - 5.75
Ballooning - 1.0

So who's willing to find out how much wind resistance there is on an e-revo @ 145mph:018:
I seriously doubt it will ever hit that speed, but it'd be really cool to try. Nevermind the ensueing explosion that'd occur if you wrecked:028:
Just a thought.

I see a couple of issues with the numbers you input that make it very unrealistic.

For one, the lipos will likely not hold 4.0V under load, more like 3.5-3.7V depending on which cells you use...maybe even less using such a high kv motor at 6S.

The ballooning is in terms of radius, not diameter. So if you had 7.75" tires due to ballooning, rest assured, you won't keep it straight enough to drive it fast.

03.25.2007, 07:16 PM

I realize that the numbers are outright insane. But even if you drop the voltage down to 3.7 under load and .5 radius for ballooniing. You still get 115mph. I'm sure the tires would probably gain 1" in radius at those kind of speeds, assuming you could find some sort of way to keep them on the rims. They'd probably shred or fly apart. I in no way expect a revo to achieve that kind of speed. I just was tinkering around and came across that speed number and thought I'd share. Granted if you ran a high MAH pack say a 10k the batteries would probably be able to keep 4.0v underload.

03.25.2007, 07:18 PM

But yea, Driving it at those speeds would be impossible. Trying to drive my revo when it was still a nitro @45 was nuts. I just wanna see it tried.

captain harlock · 03.25.2007, 07:24 PM

It's the diameter of the tires and the ballooning thing that gave you such a high speed. Try putting 5.2" for the tires dia and .25 for the ballooning and see the new top speed.

03.25.2007, 07:32 PM

Yea, tires have a huge factor on the speed. I just went with the tires off my current tire measurement. I'm sure with street tires it'd be more like 5.2-5.5. I don't have a set of m/t street tires lieing around.

BrianG · 03.25.2007, 07:31 PM

Sure, it'll hit 144 mph.... in a vacuum! :)

It won't matter what tires you put on there, it won't hit 144mph. The wind drag on a vehicle is quite substantial at that speed. It takes serious power and/or a very aerodynamic vehicle to get to that speed. The speed calculator is accurate to about 50ish mph before wind and other drag forces skew the calculation too much.

03.25.2007, 07:35 PM

Quote:

Originally Posted by BrianG

Sure, it'll hit 144 mph.... in a vacuum! :)

It won't matter what tires you put on there, it won't hit 144mph. The wind drag on a vehicle is quite substantial at that speed. It takes serious power and/or a very aerodynamic vehicle to get to that speed. The speed calculator is accurate to about 50ish mph before wind and other drag forces skew the calculation too much.

Like I said, who wants to figure out how much wind resistance there is at that speed. @ 50 the body of a stock revo seems like it wants to fly off. Nevermind 145:018: I get giddy just thinking about the idea nevermind how unrealistic it is. Makes me want to spend the $75 on parts to find out. Then rebiuld my entire revo from scratch after it wrecks.

RideIcon · 03.25.2007, 11:57 PM

Even if you could get it up to 100mph that would be a real feat! Need a very aerodynamic body and good pins:005: Some street tires that won't balloon as much. And maybe a parachute to slow it down from the rear so it won't just flip out of control when you slow down:D

glassdoctor · 03.26.2007, 12:00 AM

Think parachute for brakes...hee hee seriously that's what worries me when I think of building a 100mph car.... what do you do after you get it up to speed to keep from piling it into something trying to stop? :D

BP-Revo · 03.26.2007, 12:11 AM

Yea...I'm a little afraid already about my 5S speed runs on my 1950/6 Hi-Amp when it comes in. I should easily pull 60+ on a high geared speed run. At those speeds, I'm going to have a heck of a time controlling it. I will probably get some street tires and work hard to make sure they don't balloon.

Also, for general info, every 10mph above 65mph has 2x the wind resistance. So 75mph has 2x the wind resistance as 65, and 85mph has 2x the resistance of 75mph. This is why a 300hp car can do about 150-160 but it takes a good 500+hp to do 200mph. You can imagine how hard it is to get from 190mph to 200mph. This is why so few cars do 200mph. The Corvette, despite the fact the new Z06 has 500hp, still "only" does 196mph because of this wind resistance.

Also why it takes a whole 1001hp to power the Veyron to 253mph.

tallyram · 02:03 AM

Quote:

Originally Posted by BP-Revo

Yea...I'm a little afraid already about my 5S speed runs on my 1950/6 Hi-Amp when it comes in. I should easily pull 60+ on a high geared speed run. At those speeds, I'm going to have a heck of a time controlling it. I will probably get some street tires and work hard to make sure they don't balloon.

Also, for general info, every 10mph above 65mph has 2x the wind resistance. So 75mph has 2x the wind resistance as 65, and 85mph has 2x the resistance of 75mph. This is why a 300hp car can do about 150-160 but it takes a good 500+hp to do 200mph. You can imagine how hard it is to get from 190mph to 200mph. This is why so few cars do 200mph. The Corvette, despite the fact the new Z06 has 500hp, still "only" does 196mph because of this wind resistance.

Also why it takes a whole 1001hp to power the Veyron to 253mph.

you should be able to control that g2r with ease on pavement. i had no problems at all controlling mine running strapped road rages at that speed! my front wheels stayed an inch or two off the ground at around 40mph, and i had way more stability than the ntc3 i was racing!:dft012:

What's_nitro? · 04.08.2007, 04:19 AM

Quote:

Originally Posted by BP-Revo

Also why it takes a whole 1001hp to power the Veyron to 253mph.

If you happened to see the article about that car in Popular Science recently, The Veyron's engine actually makes ~3000 horsepower. Unfortunately, ~2000 horsepower is lost directly to heat. Which is why the car has to have 12 radiators.

Serum · 02:29 AM

Aerodynamics.. For people who can't build engines..

BP-Revo · 02:29 AM

That was said by Enzo Ferrari. I have to agree with it somewhat. As long as its not a wall, its fine.

Take the BMW M5 for example, 204mph, and its a 5 Series Sedan. All thanks to a 507hp hi-revving V10. I love this car - its my dream car. It defies nearly every logical definition of cars. A sedan that can beat high end sports cars. In Top Gear, on their test track, it pulled a better lap than a Corvette. :005: