Propeller Driven Tethered Car on eBay

Maybe if a few of us design/build and run models of this style.. we can generate more interest in the contest I pitched a few weeks back...

That certainly is a handsome model..



.. a lot easier than what I tried to do with the wheel-driven Rodd-E-Liminator for the CEF "Cars are the Starz" contest..

... but it was a lot of fun! Robert (rsv1cox) had previously given me its engine..

Hi Roddie, interesting car. What is the weight of wheel?

I LOVE that Roddy! How well did it actually go?

Levent Suberk wrote:Hi Roddie, interesting car.  What is the weight of wheel?

Hi Levent, Sorry for the late reply. I don't know how much the wheel/tire-combo weighed but it was one of "three" different types that were experimented with. Their diameters were fairly close.. but their tire's contact-areas varied widely.

The wide "slick" which I nicknamed the Phatt-Tire had the best performance.




I used bicycle-tire "inner-tube" material for the tire(s) because I could cut seamless-sections.. and stretch them over the two-piece 26mm width wheel.

Unfortunately..... having the single drive-wheel "inboard" created traction issues... because the tether's center-pylon was higher than the bridle on the car. Adding weight to the chassis helped somewhat.. but created it's own set of performance issues.

I couldn't keep tires on the car.. They'd either blow-off, burn-off or melt..




Another wheel/tire type..





Below are a pair of tires that Lieven (CEF member overlord) sent me from France. The will be the next ones to try.

LostServoScrew wrote:I LOVE that Roddy! How well did it actually go?

Thanks for the LOVE and also; sorry for the late reply. There were a lot of problems getting the car to "hook-up".. and I still haven't solved them. My previous post to CEF member Levent outlines some of the issues that I was having with tires.

My car is a 1:1 ratio/direct-drive which spins the drive-wheel the same rpm as the engine. My engine wasn't a high-performance one.. but it wasn't a slouch either. You can see the rubber-transfer on the asphalt in these vids..





Below, the excitement starts at 6:12 on the counter...  

Roddie, you may have thought of this already: elevate the tie-in points of the tether to the level, or  slightly above the level of the center of gravity of the car, so that the moment of centrifugal force should not tilt the inboard i.e. driven wheel up, and its contact with the asphalt is not lost.

Looking at the asymmetric fuselage, I would guess the CG is a few mm-s above the wheels' axle level. This level, or 1-2mm-s above this is the level where you may want to tie in the tethers.

I would not drill new holes into the fuselage, but put inserts into the existing holes with the tether having an adjustable fixing point on an arm pointing upwards from the insert...if my English correctly explains what I mean...

In addition, the aft tether could be better tied in behind and above the engine to make sure the centrifugal force does not make the car  veer off, throwing its rear towards outboard and turning its nose towards inboard direction? (Even if the tether ties in through a rod in the front, it may slightly buckle and allow the turn of the car's nose inward???)...Maybe tying in the aft tether high enough behind the engine to avoid interference with the wheel will be a 2-in-1 solution for the first point too, putting the line connecting the 2 tether tie in points higher than the level of CG?





Maybe a doubled or even tripled layer of bicycle tire inner tube on the driven wheel will also make it softer and more forgiving to the unevenness of the asphalt, and the softer wheel contact surface will not bounce up and lose contact with the asphalt so easily, preventing loss of tire to abrasion.???



But you may have experimented with these already...sorry for the layman's ideas, I have never run a tether car, just my gut feelings chiming in here...

That was fun To watch i tink the câble must be level wit the cars I wonder if the cable is placed on the top of gallon or its on the ground under??? Me for mine I had to use a long screw to screw directly into the bitumen asphalt but I had used a cable made of nylon it was a bad idea The cable stretches then the car hit a piece of ice which sent it fly End up in several barrels Luckily, I barely broke anything, just aesthetic details. Front wheel schaft bent .... this is the litle vidéo with the crash for those that has never se that one the first crash was mutch worst

I think that solid caster wheels can be used.

https://www.amazon.com/Swivel-Castor-Wheels-Trolley-Furniture/dp/B00LM5JDWI

2 inches solid rubber caster wheels:

https://www.walmart.com/ip/Swivel-Casters-2-Inch-Solid-Rubber-M8-x-15mm-Threaded-Caster-Wheels-Black/378306383

balogh wrote:Roddie, you may have thought of this already: elevate the tie-in points of the tether to the level, or  slightly above the level of the center of gravity of the car, so that the moment of centrifugal force should not tilt the inboard i.e. driven wheel up, and its contact with the asphalt is not lost.

Looking at the asymmetric fuselage, I would guess the CG is a few mm-s above the wheels' axle level. This level, or 1-2mm-s above this is the level where you may want to tie in the tethers.

I would not drill new holes into the fuselage, but put inserts into the existing holes with the tether having an adjustable fixing point on an arm pointing upwards from the insert...if my English correctly explains what I mean...

In addition, the aft tether could be better tied in behind and above the engine to make sure the centrifugal force does not make the car  veer off, throwing its rear towards outboard and turning its nose towards inboard direction? (Even if the tether ties in through a rod in the front, it may slightly buckle and allow the turn of the car's nose inward???)...Maybe tying in the aft tether high enough behind the engine to avoid interference with the wheel will be a 2-in-1 solution for the first point too, putting the line connecting the 2 tether tie in points higher than the level of CG?



Maybe a doubled or even tripled layer of bicycle tire inner tube on the driven wheel will also make it softer and more forgiving to the unevenness of the asphalt, and the softer wheel contact surface will not bounce up and lose contact with the asphalt so easily, preventing loss of tire to abrasion.???

But you may have experimented with these already...sorry for the layman's ideas, I have never run a tether car, just my gut feelings chiming in here...

Hi Andras! (I have a younger brother Andrew.. or "Andy").. I've probably mentioned that before.. but I think of you as Andy too. My brother's proper name is Andrew Vincent Jordan.. "Vincent" after our Mom's Father. I find myself more interested in my ancestry as years roll-on.  

Very good description you give; of raising the car's tether-mount(s) to suit my current layout. If I understand correctly.. it should (in theory) exert down-force on the inboard side.. which is where the drive-wheel is.

I've been thinking about your idea/reply for a few days.. and I'm going to try to apply it. Thank You!

Lots of Vincents on my father's side roddie. My Aunts (his sister) middle name was Vincent. Mostly settled in Massachusetts.

I think Andras has an engineering background.........

Levent Suberk wrote:2 inches solid rubber caster wheels:

https://www.walmart.com/ip/Swivel-Casters-2-Inch-Solid-Rubber-M8-x-15mm-Threaded-Caster-Wheels-Black/378306383

Hi Levent, I like the solid-rubber wheel/tire idea.. except that I would need to find something "thinner" (narrower) than the 2" caster/wheel shown; and it's hub to be bushed down for a #5-40 machine-screw for pairing to the crankshaft. My longest 5-40 screws are 1" (25.4mm) and I like to reserve approx. 1/2" (13mm) for the Tee Dee-style AL spinner. I have an electric starter that I use to start the engine on this car.

Any subject wheel/tire arrangement would also need to balance/spin-true at 15K+ rpm...........  I've been lucky to not have experienced any out-of-balance wheel/tire assy's. yet......  My "Phatt" wheel/tire arrangement (below)



The above imaged "wheel" are 2-pc. hollowed-out PVC (13mm+13mm=26mm width) X 1.375" dia. Their min. thickness is .100" at the hub.. so I included a cast acrylic inner-hub for strength/rigidity. With the Tee Dee style spinner (shown) and using my 1"L. 5-40 cap-screw, I catch approx. 10 threads into the crankshaft.

I prefer this set-up.. because I made the wheel/hub components myself, on a CNC machine, years ago.. and I know that they're balanced pieces. The tires.. well.. they're tires.. subject to a high-performance/severe-duty service. What I'd been using was bicycle-tire 26" size inner-tube sections.. and stretching them onto my wheel assembly. Call it a "skin" rather than a tire. I've made these by hand.. and only for a few trials thus far.. but it's afforded the largest contact-area for traction.