Chuck, exactly and totally agree: people who have a need for lugging a helix to shows.

Like it was stated before, the current size would fit in a minivan or SUV. Make it any bigger and you'd have to deal with breaking it up in multiple pieces for transportation. If you've ever been part of a modular group, you'll know that getting the rails connected / lined up from one module to the other module at a venue, is a real pain in the rear and takes time. Now try and deal with that on a broken up helix structure (2, 4 or more parts) to allow for a larger radius. The amount of module rail crossings grows tremendously and the work to get it to operate flawlessly goes up equally with the ability of things going wrong during operation going up equally. Engineering of such larger modular broken up helix would require some good structural engineering principles and workmanship to build. So yes, 22 inches radius is awfully small, but within the parameters given/needed it's likely the best option. Then having the option to use Gatorboard to make the entire helix base weigh just under 4 pounds is just another big plus. Would I build a 22 inch radius helix at my house? Heck no. But if I needed one (or two) in a modular setting? It would for sure be an option.

Most replies here are fixated on the 22”radius. For those that missed it or didn’t even watch the whole video, Joey also touted the ease of construction compared to plywood. Not just the weight and portability.  Skilled woodworkers likely prefer plywood but for others this would seem to be a good viable alternative for a permanent or fixed install helix build, which could be a larger radius.

Jeff

For your question, I would refer you back to an article published way back when in MRH that concerns car length and radius. (Sorry I don't remember how to do links here.) It's a good question but I think a separate but related one from the question of curve radii on a grade.

 I did not mean to imply a 22 inch curve radius is "wrong" for a helix. Nothing is "wrong" if it works for you. It's just that it will affect pulling power and it's a factor that needs to be taken into account. I would not want a beginner or less experienced model rail thinking they could pull a fifty car train up the thing. (exaggeration in car number for emphasis) That's all. The irony here is that I'm not even a fan of double deck layouts and/or helices unless we are talking about mushroom designs.

The relation of Car length and radius was looked at in the very first issue of MRH magazine.

John Allen calculated the curve drag as additional grade as G (curve) = 32/R

For 22'' radius this is 1.5% additionally to the grade of a helix.
Regards, Volker

@Michael.  You mean the article on curve radius and car length with the 2x, 3x etc? 

2.0 x car length - Some equipment may track reliably but 2x is generally considered pushing it.

2.5 x car length - Most equipment will track reliably if everything is of similar length

3.0 x car length - All equipment should track reliably; coupler performance ok if altered to allow 50% car width swing

3.5 x car length - Equipment will look less toy-like when viewed from inside the curve

4.0 x car length - Equipment will look less toy-like when viewed from outside the curveI've read it. 

I was thinking more in terms of helix (context here), curve + grade.

Curve Equivalent.  Basically the percent grade the train thinks it is experiencing created by the friction of going through a curve.  There is a really fancy formula that the real railroad used to calculate this, but there is a real good rule of thumb.  Take 32 and divide it by the radius in inches.  Just going through a 24 inch radius the train will feel the effects of going up a 32/24 = 1.3333 % grade.  So the 2.65 % grade of a 24 inch radius helix become 3.98% to the train. 

Due to space considerations I'm looking at a probable helix radii of 32 or 33 inches for the planned layout.  While I am not looking to use the expensive materials in the video (I don't need portability), I'll refer back for construction techniques.

UglyK5 you are absolutely right. 
“When a wise man points at the moon the imbecile examines the finger.” Confucius

Thu, 2019-04-04 08:33 — vggrek

UglyK5 you are absolutely right. 
“When a wise man points at the moon the imbecile examines the finger.” Confucius

 "people who are lugging it to shows."

  Which must be a very tiny percentage of modeler? Double deck layouts are built at home due to lack of space but shows generally should make it possible to spread out and eliminate a helix. I guess as a specialty object some might enjoy seeing it done but I'd be more interested if he could have built something more useful to more hobbyists and used cheaper material than gatorboard.....DaveB

DaveB, I would guess you are probably right.  Lugging a helix to train shows is probably a very rare thing.  In all my years of going to train shows, I don't think I've seen a helix ever.  It is an interesting exercise in necessity being the mother of invention.

But as pointed out in the video, this technique also requires no power tools or the space those tools require. It was also relatively fast with a laser (though could be hand cut as well)

So it's not just the lightness, but also the time value of money.

There's also this. Given the lightness, shipping would be very much cheaper. Imagine the op could set up a side hustle where he made these in standard dimensions for people and shipped them in low cost shipping boxes. Be interesting to see the BOM per turn on this.