Is grass a drag?

Lightweight / Folding / Portable EVs - seats optional
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ArgusMcJohnsten
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Is grass a drag?

Post by ArgusMcJohnsten » Feb 09, 2017 1:18 pm

I really wasn't sure where to put this..

I'm wanting to build an offroad skateboard/scooter, will have 4 wheels but may incorporate steering, similar to a golf board. It's sole purpose will be extremely low speeds in parks and act as a golf cart for disc golf. I'm still very early in the design phase, but I'm trying to figure out if skateboard trucks and 10" all terrain wheels will be enough, or if the grass would cause a lot of drag and I should figure out an "axle-less" configuration. Such as a highly modified frame of this wagon As said earlier, this will be very low speed, but I'm concerned about the grass hitting the trucks lowering the range.

Please let me know your thoughts and thanks in advance.

chuttney1
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Re: Is grass a drag?

Post by chuttney1 » Feb 09, 2017 4:47 pm

Yes, it is a form of drag.

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liveforphysics
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Re: Is grass a drag?

Post by liveforphysics » Feb 09, 2017 4:49 pm

Grass is draggy depending on the height and other factors.

With 10in wheels and enough torque it should work fine.
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spinningmagnets
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Re: Is grass a drag?

Post by spinningmagnets » Feb 10, 2017 1:48 pm

If it's a large and slow powerboard, consider using a single hubmotor in the rear, to make it a tadpole trike. Maybe a 16 - inch Magic-Pie?

ArgusMcJohnsten
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Re: Is grass a drag?

Post by ArgusMcJohnsten » Feb 11, 2017 10:09 am

Thanks guys. I really can't figure out which way to go. Trucks would be the easiest mounting, would give a bit of suspension, but may not be as efficient depending on how long the grass is. The "axle-less" (don't know what else to call it) would probably be cheaper, less drag, but a bumpier ride, higher center of gravity.

As for the magic pie, it would be more expensive, and I like the idea of changeable gear ratios using brushless motors and belt drives. The tadpole configuration is intriguing..it would make for one less contact patch, but would make another track of grass to be compressed as I'm riding. It would be a little less weight, but would be a little less stable.

Sometimes I think it would be good if I didn't overthink so much.

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kneedeep
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Re: Is grass a drag?

Post by kneedeep » Feb 11, 2017 10:22 am

I have that wagon for yard work and it hold a lot of weight but the plastic body is the frame its a wet noodle basically.
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ArgusMcJohnsten
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Re: Is grass a drag?

Post by ArgusMcJohnsten » Feb 11, 2017 10:36 am

I was just using it as an example of where my mind wandered to to get the most ground clearance, but thank you.

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Nordle
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Re: Is grass a drag?

Post by Nordle » Feb 11, 2017 12:25 pm

:pancake: it's not a drug :mrgreen:
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..sry for dat poor english..

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Re: Is grass a drag?

Post by Okami » Feb 12, 2017 12:27 pm

Check ''wacky boards'' website.. just search on google for it.. Im sure you will find lots of crazy ideas to properl your imagination further..

StephensEngineering
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Re: Is grass a drag?

Post by StephensEngineering » Feb 13, 2017 11:16 pm

For something very slow and for off-road only I may suggest looking for some durable small tank treads, I bet you could find something, Then incorporate a leaning system like the Swagway boards to adjust which side moves faster during leaning

ArgusMcJohnsten
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Re: Is grass a drag?

Post by ArgusMcJohnsten » Feb 14, 2017 7:08 am

Played around in sketchup and came up with this as a very rough design. Razor scooter front end for steering, the boxes with the colors in them are the golf disc holders.
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Flexscoot
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Re: Is grass a drag?

Post by Flexscoot » Feb 17, 2017 2:26 am

except if the grass is very deep, you should be fine with 10"wheels (large part of the drag of grass comes from the softness of the grass roots where smaller wheels (like 8" mtb wheels) "punctures" and causes drag )...

If you plan to ride it in seated position, that mean that your weight will be mainly on the aft wheels... in this case a delta 3 wheels could be almost as stable as a 4 wheelers and you will have the benefit of a simple and efficient steering

ArgusMcJohnsten
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Re: Is grass a drag?

Post by ArgusMcJohnsten » Feb 18, 2017 8:46 am

Thanx FlexScoot. I'll probably be sitting about 50-75% percent of the time.

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Re: Is grass a drag?

Post by ecycler » Mar 13, 2017 2:12 pm

Couple of thoughts:

1. In the right conditions (dry, short, and consistent turf) I am able to easily ride my dual diagonal longboard with 90mm wheels over grass. It has 4+kw which is beyond more than enough power, but I would not do it on a nice lawn. The wheels act kind of like mini steam rollers!
2. Make sure to get as wide and soft of tires as possible. It makes a big difference with floatation and impacting the turf the least. Your tenure of using it will be quite short if it leaves tracks and damage.
3. Your sketchup has way too short of a wheel base, unless you like racking yourself on the handlebar stem. Consider using a snowboard as the deck and reinforcing it with a frame underneath. That will likely give you a light and durable platform.
4. You can probably borrow some parts from an old california go-ped to make the build easier... things like folding handlebars are nice for transporting.
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ArgusMcJohnsten
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Re: Is grass a drag?

Post by ArgusMcJohnsten » Mar 14, 2017 11:12 am

1. The more I think about it, I probably won't need that high of frame clearance, as said, the tires will be the main contact points anyway.

2. I plan on going with garden cart, tires for testing (whenever that finally happens [darn homeowner expenses]) as they're cheap and easy to find

3. I take more a "spit it out" approach to designs and get a basic idea and make changes once I see it in person. That design is 40" wheel base, but the angle probably makes it look a little different. The handlebar stem I just took a guess on, hoping for a height that works sitting or standing. So it's probably too tall, also making the dimensions seem off.

4. I don't have a welder, so a lot of the parts will be salvaged from other items. In the sketchup, I used a razor scooter folding stem, that way I didn't have to model something from scratch. I do like the California GoPed fold design a lot better though.

ecycler
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Re: Is grass a drag?

Post by ecycler » Mar 14, 2017 12:46 pm

From my younger years I will vouch that goped bars can hold up to some serious, serious abuse!
Any grease is better than no grease.
The best exercises are the ones you enjoy doing.
I strongly prefer vehicles without doors.

Flexscoot
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Re: Is grass a drag?

Post by Flexscoot » Mar 14, 2017 12:58 pm

40" wheelbase is similar to my flexscoots so it should be ok. However, it depends upon the height of your seat, ie fully seated position or semi-seated position, as the second takes less space and is also more stable.

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