Tire ideas?

[the-one1]

I know foams cant be used, but what are the ideas for tires. I think solid core rubber tires that are very low profile so that the rubber produces the least amount of centifugal force. And also a larger diameter wheel would benefit the tope speed.

[Mike Keeney]

Tire size is something that will really need some attention. For example, an electric car running at 50,000 rpm with 2" diameter tires, and a final ratio of 2:1 will give you slightly less that 150 mph. However, the tire rpm will be 25,000. There isn't a tire in the world that could withstand that kind of centrifugal force and stay on the rim. Like it does in real life, a tire letting go at speed will likely trash the car.

Given that there is a year to build and test cars, I'm pretty confident we'll see speeds far in excess of 150mph.

The only way to overcome this problem is to run harder tires. There goes the handling. It will probably be a good idea for the promoter to require all tires to be covered by the body somehow. The answer will probably be with urethane. It can be mixed almost as hard as plastic. It's going to be interesting hearing about the various problems everyone will experience when they start testing their cars at speed.

Mike

[Grant Tokumi]

roller blade or skateboard tires???

[DaFF]

I don't see urethane having enough grip to propulse an r/c car.

Urethane wheel are usually used in the industry for cart and any type skids that need wheels. It widhstand heavy load, but for an r/c ???

Anyway, everything is still possible....

I'll rather go with foam like on the 1/8 type car. They are of raisonnable outside diameter, they are fairly wide ( hence good traction, good handling ) and they stay put on the rim at least at more than 80 mph, no need for testing, I've witness it many it time.

BTW, watch all the scale dragster, that's what they use and they are not shy of 100+ mph passes.

Foam is good because it is so light that it's reduce centrifugal force a lot - centrifugal force being straighly derivated from the weight of the piece you are rotating - It will recude overall weight too and also rotational mass.

Fc = mv2/r

where Fc = centrifugal force, m = mass, v= speed, r= radius

That's the reason why I wouldn't go too crazy about big tire od.

I think it would be easier and safer to use a 4wd vehicule with 1/8 foam. As a bonus, it is easy to get, cheap and available in many different shore ( hardness)

The more tire weight, the more chance your tire will flew off the rim.

You sure can reinvent the r/c wheel ( ! ) , but to my opinion, within a fairly tight ( less than one year ) time frame, you'll have enough stuff to worry, test and think about !

I would just test it to speed anyway before trying something nobody has ever done before, but that is only me...

Good luck in your project Mike !

DFF

[DualBL]

I personally am not worried about tires "exploding" or anything of that nature.
watch this video:
http://webzoom.freewebs.com/prezprojects/smoke.wmv

that's a Hacker B50 8s on 16 cells which is:
4613rpm/v x 1.2v/cell x 16cells = 88,569.6rpm.

when the tire doesn't balloon, it's about 2.5", when it ballooned in the video, it was about 3".

when calculated, in my tc3 which I had a FDR of 2.5, a 3" tire dia, and the motor spinning at 88,000, the calculated speed is 314.159MPH.

notice how the tire never "exploded" it got tore up, because it was basicly melting/digging into my driveway, getting cut up on the rough surface. but if the car was actually moving at that speed (which i know it wouldn't, but let's assume it was) the tires would balloon to that size but they wouldn't explode.

i think i got all that out the way I wanted to.. maybe not, and I'll get flammed, but at least i tried.. right?
-Nick

[cool head]

well i've been experimenting with tires using a die grinder that spins at 18,000 rpm. a 1/10 tire will be spinning over 13,000 rpm to break a record. all the tires ive tried have completely seperated from the rim. it's a great way to remove tires from rims! so far the foams have held out the best. its gonna be a tires that beat the record IMO.

[Speedtester]

Did you consider the load on the motor and the gear reduction. Besides that aerodynamics would cut that number way back.

Originally Posted by DualBL

I personally am not worried about tires "exploding" or anything of that nature.
watch this video:
http://webzoom.freewebs.com/prezprojects/smoke.wmv

that's a Hacker B50 8s on 16 cells which is:
4613rpm/v x 1.2v/cell x 16cells = 88,569.6rpm.

when the tire doesn't balloon, it's about 2.5", when it ballooned in the video, it was about 3".

when calculated, in my tc3 which I had a FDR of 2.5, a 3" tire dia, and the motor spinning at 88,000, the calculated speed is 314.159MPH.

notice how the tire never "exploded" it got tore up, because it was basicly melting/digging into my driveway, getting cut up on the rough surface. but if the car was actually moving at that speed (which i know it wouldn't, but let's assume it was) the tires would balloon to that size but they wouldn't explode.

i think i got all that out the way I wanted to.. maybe not, and I'll get flammed, but at least i tried.. right?
-Nick

[DaFF]

Yeah, what a disappointment, Dual BL is only shooting for 314 mph

C'Mon, you better raise the bar if you want to keep-up with me, I am shooting for the sound barrier, less is a lil tame LoL

Coolhead, yes, that confirms what I though, foam are excellent, it's embedded in the centrifugal formula I gave

DFF

[DaFF]

For those that are serious in the quest for speed, I highly recommend to be very carefull with tires, and IMHO all tires would need to be PRECISELY balanced.

In order to do so, I think something like this prop balancer would help a lot:

From Tower Hobbies:

The Top Flite balancer is an innovative way to balance your aircraft or boat
propellers, spinner backplates, car wheels and tires, as well as many other
items in the hobby industry.

FEATURES: Precision ground balancing shaft, held between two powerful "Ceramic 8" magnets allows shaft to "float" for maximum sensitivity Inexpensive and easy to use...essential for every modeler. Reduces prop vibration-reducing engine wear and prevents structural damage Can be used anywhere-on the workbench or at the field Constructed of long-lasting, high impact plastic and nickel steel Includes instructions explaining how to correct out-of-balance props, and even how to use the balancer to determine wind speed. Can also be used to balance boat props, car wheels and tires, ducted fans, spinners, nose weights and more! Balances up to 24" propellers and any size wheels and tires.

INCLUDES: Two Ceramic Magnets (GP# METAL058) Two Molded Plastic Side Plates (GP# NYLON92) Two Metal Rods for Base Support (GP# WIRES81) One Balancing Shaft (GP# WIRES80) Two Plastic Propeller Locking Cones Two Lexan Magnet Covers (GP# PSDC001) Two Thumb Screws (GP# SCRW102) .

REQUIRES: CA to glue lexan magnet covers to magnets.

SPECS: Transport size: 2-1/8" x 7-1/8" x 1-5/16" Assembled size: 2-1/8" x 7-1/8" x 7-3/8"

COMMENTS: Balancer is "VERY" sensitive, VERY accurate.

DFF

[DualBL]

i know, what I said is not accurate, and wasn't with no load, so the 300mph+ thing is void, but what I'm trying to say is that the tires were spinning incredibly fast, and never had a problem with comming off the rim. on my other vid, the tire seperated from the rim, but that's because I used very little CA.

think about all the ballooning vids that you've seen on monster trucks. motors like 1930/5 with 12 cells, and no load, and those huge mt tires stayed on the rims just fine.
-Nick

[DaFF]

I was only j/k...

Anyway, yeah, MT tire ballons like crazy @ speed, it's kind of funny to watch.

Wouldn't want to have my tires ballooning like that during 100+ mph pass, you need to be stable, not to float over the asphalt !

DFF

[racerrandy]

I am concerned about the wheel too. Seems like I never get a wheel from my lhs thats runs really true. I was thinking about aluminum wheels like what Hardcore makes. You could easily mount foam or run a belted tire. I was thinking of having some super nitro size wheels made. I think everybody is going to have plenty of power with whats out there these days, its going to be the little things like tires,wheels,body,and suspension that makes the deal.

[Maxxcrazy]

What about beadlocks? I think they would hold a tire better than glue, but they are only for rubber tires, not foam

[DaFF]

Wouldn't be so sure about alum wheels.

OK, it will sure run very true, especially compare to the molded pastic rims but the problem is the gluing.

The glue doesn't stick very good to alum, thus tires on alum rims will be less seated than on plastic rims and more prone to split under heavy centrifugal force.

Anyway, one could find the perfect glue and gluing process for this application.

Beadlock might be the deal, because tire will be hold firmly - but as said previously rubber only -

My experience also about wheels not running true is that very often it is not the wheels itself but the wheel axle carrier or the way the wheel seat on it.

The slightest bend on the carrier and you are done.

A wheel not properly seated on the hex and ... bad woobling.

Quality of the bearing would be a big + too i.e. play will work against you.

I guess that would be as well something to check thoroughly.

Everything needs to be perfect to reach those speeds.

DFF

[patcook]

My question is what about 1/5 scale tires. They're a little bigger, and so they might hold up better, and they would also let you run a lower cg compared to the tire so the car might be a little more stable. maybe a beadlock rim and 1/5 scale tires would work well also.

[StormPilot]

Hey guys. I have seen rollerblade wheels mountes and run on many R/C cars. The reason that guys around here started doing this is because in the winter, we run on a roller rink. The blades wheel are the only thing that gives us traction. We can actually take the oval turns at speed. The guys around here are running HPI's and TC3's some running mods and some running 19turns. I think that if you can figure out how we do it, you could get some really great speeds and the handling is insane. The wheels grip well in the corners because of the shape. You also have very little drag since the contact patch is very minimal and the grip is really high.

Darin Gray
RCSX Eugene

[Toyotatogo]

Pmt Tires .....

[promodvette]

The tires I am going to use are 4 inches total with a 3 1/2 inch machined aluminum wheel. The Hard rubber tire will have "beadlocks" more less the wheel will be screwed directly into the wheel. The rubber is a hard type that is used in conveyer belts and is somewhat flexible yet hard and will not expand

[Mike Keeney]

Originally Posted by promodvette

The tires I am going to use are 4 inches total with a 3 1/2 inch machined aluminum wheel. The Hard rubber tire will have "beadlocks" more less the wheel will be screwed directly into the wheel. The rubber is a hard type that is used in conveyer belts and is somewhat flexible yet hard and will not expand

I can sure vouch for conveyor belts. They're tougher than wang leather. We make a product that has a rubber to aluminum bond. Over the years I've tried just about every kind of glue known to man to keep the rubber where it's supposed to be. About a month ago we contacted a rubber company here in Reno and asked them if they had any suggestions. They sure did. They gave me a couple cans of some horrible smelling goop and told me how to mix it up. I followed their instructions and mixed up their witches brew and glued a couple sets up. The next day I couldn't pull the rubber out of those blocks if my life depended on it. Turns out this stuff is some kind of cold vulcanizing compound they use to glue these super long conveyor belts together. Those things have hundreds of tons of weight they have to pull and the splice will never give up. When I get to the shop tomorrow I'll post the info on the stuff.

I had to laugh about one thing though. I mixed the stuff up in one of those little plastic cups the restaurants use for sour cream or butter. When I got in the next morning the goop had disolved the cup and had glued itself to the table. It took three strong men and a baby gorilla to get that crap off my table.

Mike

[Oldway]

A number of years ago I built an insane car for the Domingus velodrome. It was a Bolink Nitro Racer with a Nova Rossi .12 w/.46 size carb. Total weight 52oz, geared 1.75/1, TRC capped tires with fiber glass reinforced wheels and re-glued with wet suit glue.
I balanced and chucked the wheels into a 25,000 rpm router, and they held together.
Tried to keep everything under the body so I used the wrong pipe and never really got up "on the pipe" Result was just under 70mph. It handeled great and if I had used the right pipe I think it could have done 90mph on that track.

[Oldway]

Oh yeah, another alternative tire is the rubber off an old Futaba 2PBK radio, fits right on the rim, is solid and shaped and has good traction.

[mgs9]

At the fastest car challeng what type of race way is it going to be, Asphalt, concreat ,ect because that will make a big diffrence in what tire should be used. They just repaved the road by my house its all asphalt now, i took my car out there, it has foam tires, and it was pealing tire like theres not tomorrow.

mgs9

[Oldway]

The track is banked asphalt with three different degrees of banking and lots of rubber laid down

[Stocker452]

I think you guys should make an adapter for wheels to spin on a dremel. Dremels get about 35,000 RPM...thats at least the RPM of what the tires are gonna be spinning at during the record attempt and testing.

Custom made foams will work...maybe some sort of epoxy to put on the rims will soak into the tire a couple Millimeters and keep it stuck on there...then the rest of the tire,about 10 mm, will be normal soft compound, this would prevent the foams form desentigrating

[EddieWeeks]

edited