41 replies to this topic

[One_Track_Mind]

Well... you might say that!



While attending a Penn/Ohio Retro race @ Rt.93 Raceway, John Humberger knows how much Mr.Frank loves Thingies so he brought along this marvelous piece to show and tell. I wish at this point and time that I could recall his name? (the builder),but I met so many people and old age is catching up that I've forgotten his name,but not to worry, soon as I find out. The credit will be given.

Onto the bat cave...
















reason for Edit: John Humberger

[slotcarone]

Did he put it on the track? How did it run? Inquiring minds want to know!!!!!

[One_Track_Mind]

Hi Mike,
We did not get to see this car run.
Reason being, the power was not turned on at the drag track. It will not fit under the bridge on the king.

When I was talking with John He said it does run, and during first design proto-type stages, the car done a back flip and the prop whacked him across the knuckles!

[Duffy]

With reverse-polarity braking, MAYBE--

And he oughta turn the prop around. He's got it on backwards.

Duffy

[One_Track_Mind]

Hi Duffy,

Yea, I don't know much about the mechanics of the car other then looking at it? If the prop is on backwards, maybe it is? for a reason...we will have to address these concerns to him.

It is kinda neat though hugh?...John said he got the idea from a swamp ride buggy thing? what are they called? Air Boats?

[havlicek]

I built a prop-driven slot car in the 60's using a regular Mabuchi motor in an inline configuration (no gears and no body either) with the motor angling up towards the rear. It went around the track once with absolutely zero brakes at a slow speed and that was that.

-john

[Brian]

I was told yesterday that it runs 18mph down the drag strip.

[Jairus]

Hmmm... seems like a cool proxy race idea to me!

[endbelldrive]

Oh yaaahhh...I've got to build a prop car too!

[Guy Spaulding]

Wow! Here's something I've done before!
Twice, even!

First time was in the 60s. We called them "Propmobiles".
I remember attaching a 1 1/2 Volt dry cell battery to my brake line to get the propeller to spin backwards to help slow down at the end of the straights




Then again in the 80s. That's my experimental twin-motor UFO from Area 51, against Foamy's (Dennis Hill) champion RC motor "Bladerunner" rail car at Valley Raceway in Rosemead, CA. Maybe foamy remembers how fast we went. He did this a bunch, while I was the impostor from Las Vegas.

[Jairus]

So fastest lap motivated only via propeller power is the winner huh? I got one of those Havlicek piano wire wound arms that is just screaming for this project!

[Bill from NH]

I built a prop-driven slot car in the 60's using a regular Mabuchi motor in an inline configuration (no gears and no body either) with the motor angling up towards the rear. It went around the track once with absolutely zero brakes at a slow speed and that was that.

-john

John, it probably just needed a hotter arm! A prop-powered gokart would be pretty nice if you could find a JK body.

[DirtyHairy]

yes!!!!! was a very interesting lookin car, and tried to get him to run the oval, but as was said these cars have very little (if any) brakes..... but it looked very well built and designed , so A+ sir

[havlicek]

John, it probably just needed a hotter arm! A prop-powered gokart would be pretty nice if you could find a JK body.

I guess Bill. Honestly, I think key is getting the right prop (lotsa blade and steep pitch)...and a serious motor. If you nuts get a race together, I'll be on someone's team and supply a motor Oh...and no drags, these things should have to be able to go around a track. How long before someone comes up with an electronic clutch-type brake system where the inline gears would normally go ?

-john

[Jairus]

BRAKES?

We don't need no stinking BRAKES!!!!

[Jairus]

Okay, if you will indulge me for a few....

I believe with enough downforce and a low CG there will be no need for brakes. Rear tires are soft rubber for good side to side traction, freewheeling of course. Prop rpm's only need be 1/3rd the speed of the motor for additional torque. John is right however about the prop being critical...
... gotta' look for the right prop!

[Pablo]

Duffy, the rotation looks correct to my eyes - please explain ?

[havlicek]

Jairus,

Does your mind ever stop working so hard? I think your drive arrangement is actually a really good way to do this...if anyone were so inclined You definitely have to have the motor in front of the rear wheels to avoid wheelies and your arrangement just sorta looks workable. Heck, the body you stuck in there even looks like it would be a good candidate. A long piece of .078 piano wire with a bushing on either end to carry both the prop and the spur gear and you've got a workable car (as long as you can find the right prop). Here's some 2.5" pusher props...but they look fragile and the plastic would have to be fastened to the shaft with jamb nuts


Here's some nicer looking pusher props of around 4.3" for $4.50


...maybe for some extra "oomph", you could use a helicopter tail rotor blade . Bigger blade area in a shorter prop. Here's a 4" one for $3

After the race, the thing could do double duty as a food processor.

-john

PS...for some reason the pictures won't show, but Tower Hobbies has a pretty good selection

[Jairus]

John,
Good ideas there. Tower Hobbies was my first stop but I would rather hit the Hobby Shop first. Looking for a prop no larger than 3". Reasons are that the bridge clearance is about 4.5 inches and I want to try and keep the car at least legal width and pass under the bridge.

A Helocopter rotor blade is not very efficient. It pushes only enough air to counteract torque and work as a rudder. I think something like you suggest, large surface area, is the best solution. Also considering counter-rotating blades so that will require finding two props with equal cross-sections but opposite rotations. The current layout keeps the gearbox down with a low CG and duel shafts running up to the back. I was hoping to use my Carbon Fiber shaft but with countra rotating props... will require a shaft in a shaft with ball bearings inside and out! Otherwise the friction will kill before it gets off the bench! Still in the planning phaze with too many other projects ahead of this one to start building. Just spit balling at this time.

Oh... and I also want a pair of rudders behind the blade(s) connected to the guide to help steer the craft through the turns. I believe this will eliminate the need for any brakes.

J

[Mr. Frank]

O K GUYS; Saw johns ride at the shop but he showed it to me about a year or so ago. I think it's time to BUILD... LOOK OUT. Boy this is gona be FUN... Thanks john, I will be bringing mine to bears next month.. O- YEA , time to craft!!!!!!!!!!!!!!!!!!!!!! NOW TO FIND A BODY. Off to k-mart.. Mr. Frank

[Guy Spaulding]

If anyone chooses to go with dual propellers, I used props from a Cox .10 engine.

[Duffy]

Duffy, the rotation looks correct to my eyes - please explain ?

Rotation's fine, it's the orientation of the prop. Look closely at the photos: you can see a camber to the blades, a convex curve on one side and a flat or hollowness on the other. for this application, the hollow side should be on the rear and the humpy side should look forward. This is the "right" way to use the prop for max lift (or thrust or whatever--model flyers argue terms all the time and the language of props is fuzzy).

Duffy

[proptop]

Cool idea

Check out the APC brand of propellers (Tower has 'em)
The "E" and "SF" series are specifically designed for electric power.
The "SF" or Slow Flyer have a highly cambered and thinner airfoiled blade designed for max. efficiency at lower r.p.m. (around 10K or less) but I don't think they have one small enough for what youze guys might need?

The "E" series are designed for substantially more powerful motors on faster models and will take much higher r.p.m. and they have 'em in smaller diameters. Maybe some of the props for "Speed 400" motors will work for you, seeing as you're using gear reduction?

GWS also makes a good (thin, light and efficient) elec. prop...and they're cheap so you can experiment with different diameters and pitches w/o spending a lot.

Props that were originally designed to work on glow engines aren't all that good on an elec. motor...they are unnecessarily heavy and thicker blades absorb too much power with less thrust in return.

I've been flying R/C with electric power for about 10 years...
Started w/ brushed motors and Ni/Cd's and now with brushless motors and Li/Po and Li/Ion batteries...amazing developments in the past several years!

[Jairus]

Hmmmmm, thanks for the info Tom! (Jairus happier now)

[Guy Spaulding]

Gr8 info, Tom!
The advances of electric powered flight has brought a wealth of availability not seen in the 80's when I last built mine.