WM RC

[viejoronnie]

I went to WM to pick up a few $10 1/64 2.4 GHz Pocket Racers for the electronic bits and saw this attractively detailed 1/18 2.4 GHz desert runner with metal panels.

I bought it just to see what was inside and see if I could modify it. At $15 ...why not? My philosophy on buying such “throwaway” project toy items is that if it costs me less than $2 in 1965 dollars then I’m all in. Besides, it came with a 3.7 v 500 mah Li Po that would cost you $5-8 alone so that gets the cost down to like a buck in 1965 terms.

As expected It has binary steering and binary speed control and is not very swift. I am going to see if the receiver motor controller can handle 7.4 v with two batteries.

Push come to shoveI can always put in one of my $5 2.4 GHz Proportional ESC receivers for low speed action.

[SpeedyNH]

i have a 1/18 rock crawler. it's a lot of fun when i go to the desert for work.
speedy

[viejoronnie]

I did a few speed runs on smooth concrete and dirt with a fully charged LiPo. I was pleasantly surprised how zippy it was. Not as fast as my 18 fps 1/32 2.4 GHz RC-based slot cars, but ok for what they are. It handles pretty well even though it only has binary steering and throttle.

The motor is a Chinese Mabuchi 260 clone that revs to 10,500 rpm @ 3.7 v. Since there is no proportional ESC to worry about frying with higher voltage, I don’t think doubling the voltage will kill the board components, but I will find out. The 260 motors can easily make 20,000 rpm at 6 v, therefore I’m hoping for about 20 FPS @ 7.4 v.

[ourwayband]

Interesting project.Keep us informed..

[viejoronnie]

The battery compartment has enough room to install up to three 1000 mah 3.7 vdc LiPos (in either series or parallel) for supplying a max of 11.1 vdc/1000mah for high speed operation for an hour period or 3.7 vdc/3000mah for lower speed operation for up to a three hour period.

[viejoronnie]

Apparently the pcb receiver circuit design has a high voltage protection circuit that will not allow more than about 4 vdc to flow from the battery to the motor.

No worries, since I can basically either hard wire a single 3.7 v battery and switch directly to the motor and use the cars 2.4 Ghz control as a turbo/boost control; OR instead of a hard wired single full on speed to the motor, use one of my $5 proportional 2.4 Ghz RX to provide a proportional speed boost thus using two TXs. Talk about having to multitask. LOL

[viejoronnie]

I found a youtube video on this same toy grade car from a German toy store.

Instead of a LiPo battery like the WM car it was equipped with a 4.8 v NiCad battery pack, which makes sense given the large battery compartment size.

The German description below the video stated a top speed of 20 kmph (or 18fps), which makes sense given the apparent speed of my WM car at 3.7 v.

Next I will build a 4.8 v NiCad battery pack to attempt to get around the voltage limiter on the pcb but get a decent speed increase.

[viejoronnie]

From my calculations the final drive ratio is near 8:1.

I pulled out my bags of Chinese gears and found a combination that will result in about a 4:1 ratio.

[viejoronnie]

I have found an 260R motor rated at 15k rpm @ 3v, so my need for speed seems to be satisfied regardless whether I use a single 3.7 v Li Po or a 4.8 v Ni Cad battery pack.

I shortened the mounting posts for the rollcage and removed most of the interior pan, except the dash, to get the cage frame to sit lower on the RC tub. The car now has a more scale appearance. I have a 1/18-1/20 driver figure coming to mount on a card interior. I’m planning to hydro dip the metal body panels.

Once I get this first one done, I may build several more to have a stable of similar performing cars for my birthday party slot car/RC car biz.

[viejoronnie]

I went to my local Hobbytown to get some supplies and found a Radio Shack 4AA battery box already wired for series operation.

I wired the box up to the existing car power connector.

The motor speed increased from 10,500 rpm to over 13,000 rpm by putting a little over 5 v into the car, however the weight of the NiCads does affect over-the- road performance.

If there was not a high voltage limiter built into the pcb; this thing would fly with the stock motor and 2 3.7 v Li Pos.

I just ordered a few 15,000 rpm 3 v R260s from China.

It will be interesting to see the performance I get out of these with a single lighter 3.7 v LiPo.


While waiting for the higher rpm motors, I will build a 4.8 v AAA battery box which will fit into the existing car battery box. Instead of 4.8 v/2200 mah , 4.8 v/900 mah should be satisfactory and much lighter.

[viejoronnie]

Using 4 AAA Ni MHs @ 5+ v with a 15k @3v motor wotks out to be a speed of 30 kph /18 mph/19 fps.

Not too shabby for an $4 (in 1965 $ including batteries toy car; acknowledging that such wireless control and battery power technology did not exist then like what we enjoy now.

[viejoronnie]

I picked a couple of junkyard lots of Ertl 1/18 diecast hot rods.

I had the idea to use these to create some oval racing jalopies using my WM 1/18 RC car chassis. The choice is to use the diecast body as a resin and/or vac master to create a lighter and/or wider body to fit the chassis OR to deconstruct the chassis/use the bits for a narrower chassis. I am leaning toward the latter combined with a resin/vac repop scale body. I will retain much of the RC roll cage which weighs nearly zip. The cage design (with some judicious mods) already resembles that of track jalopy.

[viejoronnie]

Well ... massaging (aka destroying) the RC chassis to accept a resin repop of the Ertl 1930’s body is apparently above my pay grade.

So I’m thinking about creating a body that sorta resembles a jalopy body out of sheet bass and balsa wood/plastic sheet that fits like a glove over the stock RC chassis with a cut down crash cage.

I did acquire the perfect 1950s 1/18 scale driver complete with rolled up shirt sleeves, seat belt, goggles, bandana, and jockey helmet (from a 1950s toy car). I think I will make a few resin rep ops of this guy.

Here is the look I am going after.

[ourwayband]

I like that look!!

[viejoronnie]

My new 27000 rpm (@4.8v) 260 motors just arrived via a slow boat from China. Now to see if I can get these bad boys going faster. I was going to buy a couple more but all the WM are out if stock.

What about turning the chassis around and reversing the wiring on the ESC,etc, to make it front wheel drive with rear wheel steering for “more efficient” crawling?