What determines scale?

[biggman100]

I really don't get it. Do manufacturers just make up scale sizes? A guy I know has a Cen M Sport rally car, which is listed as 1/8TH scale, but, it's actually a little bit shorter than my Traxxas Fiesta Rally that's listed as 1/10TH scale, so, what actually determines scale? Is it just the rated power (2S, 3S, 4S), or, is it something else?

 

[tudordewolf]

I really don't get it. Do manufacturers just make up scale sizes? A guy I know has a Cen M Sport rally car, which is listed as 1/8TH scale, but, it's actually a little bit shorter than my Traxxas Fiesta Rally that's listed as 1/10TH scale, so, what actually determines scale? Is it just the rated power (2S, 3S, 4S), or, is it something else?

That Traxxas is definitely more comparable to a 1/8th scale than a 1/10th, it's the same general scale as the HPI WR8, which is 1/8th (The HPI is even slightly smaller).

Rally car models specifically tend to be a little weird because they're more like 1/10th short-course trucks under a 1/8th-scale onroad body shell.

It might be easier to frame things in nitro terms to see where this came from: 1/10th is powered by a small-block (tpyically .12-.18), and 1/8th is powered by a big block (.21 and beyond).
There's 1/10th and 1/8th onroads, buggys, short-course and monster trucks, and they all stay in their respective weight classes. The aforementioned "rally car" issue emerges because the onroads, no matter how much you raise the ride height, just aren't going to handle well off-pavement, so manufacturers make a "1/10th rally car" by putting an oversize bodyshell on a buggy/truck chassis.
Another that does the same is the HSP Kutiger.

 

[Ritz413]

I really don't get it. Do manufacturers just make up scale sizes? A guy I know has a Cen M Sport rally car, which is listed as 1/8TH scale, but, it's actually a little bit shorter than my Traxxas Fiesta Rally that's listed as 1/10TH scale, so, what actually determines scale? Is it just the rated power (2S, 3S, 4S), or, is it something else?

Scale is a wierd thing in this hobby. In literal terms it is supposed to be a size reference to the actual vehicle. If that were true you could take the specs like wheelbase from the original, and compare with the model. In rc terms, scale often represents good marketing, where the consumer will recognize a 1/10 scale offering as a product with 12mm hexes and a 540 can motor. Makes shopping aftermarket easier if it's done with a broad stroke.

 

[RustyUs]

 

[RudyF6]

Every one of these are consideres 1/10th.
The closest to accurate is the RGT Bronco, last one on the right.

 

[desmobob]

I always thought wheelbase measurement was the basis for determining scale but the RC industry doesn't stick to that, for sure!

 

[biggman100]

That Traxxas is definitely more comparable to a 1/8th scale than a 1/10th, it's the same general scale as the HPI WR8, which is 1/8th (The HPI is even slightly smaller).

Rally car models specifically tend to be a little weird because they're more like 1/10th short-course trucks under a 1/8th-scale onroad body shell.

It might be easier to frame things in nitro terms to see where this came from: 1/10th is powered by a small-block (tpyically .12-.18), and 1/8th is powered by a big block (.21 and beyond).
There's 1/10th and 1/8th onroads, buggys, short-course and monster trucks, and they all stay in their respective weight classes. The aforementioned "rally car" issue emerges because the onroads, no matter how much you raise the ride height, just aren't going to handle well off-pavement, so manufacturers make a "1/10th rally car" by putting an oversize bodyshell on a buggy/truck chassis.
Another that does the same is the HSP Kutiger.

Thing is, it's been like this going on 30 years or more. I've had 1/12TH scale buggies and monster trucks in the past that were pretty much the same length as the 1/10TH scale ones. I always thought they were supposed to be exact scaled down versions of the real vehicles, but, they aren't always that either. The older 1/12TH scale Tamiya beetle, unless my math was wrong, was more 1/10.5 scale than 1/12TH scale, compared to the real thing. It's why I think a lot of the companies just make up the numbers sometimes. The worst has to be Redcat (HSP) though. Literally all of their 1/10TH scale cars with the purple or blue upper chassis brace are the exact same size (monster truck, drift car, rally car, short course truck, desert truck, buggy, touring car). They all have the exact same wheel base, length and width, and they are all pretty much the same size as most 1/10TH scale monster trucks from other companies. Take the HSP Kutiger you mentioned. They use that exact chassis in every 1/10TH scale where the model number starts with 94. I buy those cars as kits from AliExpress, in different versions, and, other than the body and wheels and tires, and bumpers, everything else is exactly the same.

 

[tudordewolf]

Thing is, it's been like this going on 30 years or more. I've had 1/12TH scale buggies and monster trucks in the past that were pretty much the same length as the 1/10TH scale ones. I always thought they were supposed to be exact scaled down versions of the real vehicles, but, they aren't always that either. The older 1/12TH scale Tamiya beetle, unless my math was wrong, was more 1/10.5 scale than 1/12TH scale, compared to the real thing. It's why I think a lot of the companies just make up the numbers sometimes. The worst has to be Redcat (HSP) though. Literally all of their 1/10TH scale cars with the purple or blue upper chassis brace are the exact same size (monster truck, drift car, rally car, short course truck, desert truck, buggy, touring car). They all have the exact same wheel base, length and width, and they are all pretty much the same size as most 1/10TH scale monster trucks from other companies. Take the HSP Kutiger you mentioned. They use that exact chassis in every 1/10TH scale where the model number starts with 94. I buy those cars as kits from AliExpress, in different versions, and, other than the body and wheels and tires, and bumpers, everything else is exactly the same.

That's what I love about them - I did a bunch of nitro builds, from a TRX 3.3 to an SH.12, all wrapped up in a build thread here. I can "support" them all from the same pool of diffs & core components, but tune them each to be a unique vehicle.

There's a few more things than you mention that set them apart - the onroads and offroads use a different chassis; the offroad one is a bit longer and has a slightly bent-up front lip.

At least for the nitros, they give me a lot of options in an era when most manufacturers are only offering 1 or 2 vehicles.

The short-course truck has doubled-up suspension, the monster truck (94188) has a single-speed, extra-low gearbox that can pull wheelies on its beefy tires.

Thank to the part commonality, you get 2 choices of 2-speed gearbox, (one is 39/44 and the other is 42/47), and you can find other clutch bells for extra tuning options, which I even mixed into a third option using the smallest and largest ratios to create an extra-wide gearing. (39/47 and a 13/21 clutch bell)

By flipping around the rear A-arms on one of my onroads I made a "short wheelbase" version, the options go on and on.

 

[biggman100]

That's what I love about them - I did a bunch of nitro builds, from a TRX 3.3 to an SH.12, all wrapped up in a build thread here. I can "support" them all from the same pool of diffs & core components, but tune them each to be a unique vehicle.

There's a few more things than you mention that set them apart - the onroads and offroads use a different chassis; the offroad one is a bit longer and has a slightly bent-up front lip.

At least for the nitros, they give me a lot of options in an era when most manufacturers are only offering 1 or 2 vehicles.

The short-course truck has doubled-up suspension, the monster truck (94188) has a single-speed, extra-low gearbox that can pull wheelies on its beefy tires.

Thank to the part commonality, you get 2 choices of 2-speed gearbox, (one is 39/44 and the other is 42/47), and you can find other clutch bells for extra tuning options, which I even mixed into a third option using the smallest and largest ratios to create an extra-wide gearing. (39/47 and a 13/21 clutch bell)

By flipping around the rear A-arms on one of my onroads I made a "short wheelbase" version, the options go on and on.

I never really got into the nitro or gas stuff, I have always pretty much stuck with electric, but they aren't any different. Pick a chassis, and build different vehicles from it. With the HSP electric stuff, you can build at least 8 different vehicles from one chassis, using the same diff's and drivetrain. A lot of people don't like them, but I do.

 

[tudordewolf]

I never really got into the nitro or gas stuff, I have always pretty much stuck with electric, but they aren't any different. Pick a chassis, and build different vehicles from it. With the HSP electric stuff, you can build at least 8 different vehicles from one chassis, using the same diff's and drivetrain. A lot of people don't like them, but I do.

I misread your "worst about it" line. I have every HSP nitro and 2 of their 1/16ths, and built an electric car and truck. I do wish I had more gearing options for the electric models.

They made pivot-ball versions of all the 941xx nitro vehicles, but not the electric lineup, which seems like a big missed opportunity; the pivot ball versions are more durable and have less steering play. You could use the electric conversion mount on a nitro chassis to make a unique, pivot-ball suspension electric HSP.