First attempt on a PF RC Car

[M4X1994]

So I recently ordered some XL-Motors and I decided to make a fast RC car powered by 2 XL-motors and a medium motor for steering.

It has 2 XL-motors for driving, a M-motor for steering and a PF switch to turn the led lights (2 at the front and 2 at the back) on or off. Everything is powered by a battery box with 6 1,2V rechargeable batteries. Please tell me what you think, its quite fast so I think it worked out pretty well for a first attempt.

This is what it looks like:

From the front:

From the side:

Under the hood:

At the back (Note the PF switch for the lights), the 4 cylinder engine works:

Inside the car (Camera didnt focus, should have put it on macro):

On the roof:

And under the car:

Feel free to ask questions and both positive and negative reactions are welcome.

I will probably make a video of it some other time and upload it to my youtube channel. (the car is surprisingly fast)

[Zerobricks]

Wow 2 Xl motors? That has to be fast and strong! Good job especially because its your first!

[dolittle]

Very nice design and interesting choice of XL motors.

Wish you had an LDD of it :)

[M4X1994]

Yeah, its fast, but quite heavy too, 1,4kg

Very nice design and interesting choice of XL motors.

Wish you had an LDD of it :)

I have absolutely 0% of experience with those programs, but i might try and make one, that is if my computer can support it.

[legolijntje]

Yeah, its fast, but quite heavy too, 1,4kg

I have absolutely 0% of experience with those programs, but i might try and make one, that is if my computer can support it.

If you want to make a LDD of it, you will need a "special mode" called LEGO Universe. Look in the ldd forums for more info.

The car looks great!

[M4X1994]

I just started working on the LDD model, I have no idea how long this will take, but probably long!

[Alasdair Ryan]

great first moc

[M4X1994]

great first moc

Thanks, but its not my first MOC, its just my first RC PF car.

I cant find

in LDD, is it not there or am I blind? I hope the latter because i want to finish this model :p

[rgbrown]

Feel free to ask questions and both positive and negative reactions are welcome.

Wow, it looks really good. I love how compact the functionality is. Very nice car!

I'm wondering how well the two XL motors will work coupled together that way, as that forces them both to run at exactly the same speed -- I would wonder if one of them would end up doing most of the work while the other has a free ride. But I'm not sure whether this would happen or not.

I'm also guessing a differential adder wouldn't fit, or be strong enough. I'd be curious to see how much worse it works if you disengage one of the motors...

[DLuders]

I cant find [the 5x7 Technic Liftarm frame] in LDD, is it not there or am I blind? I hope the latter because i want to finish this model :p

No, it is not there, but LDD Master Zblj has made substitute "LDD Custom Bricks" .lxf files available on this Eurobricks post.

As mentioned before, in order to have the greatest selection of Technic parts, be sure to use LDD "Lego Universe Mode".

Edited December 31, 2010 by DLuders

[M4X1994]

So after lots of frustrating hours in LDD i finished the model for those who asked for it :)

The model:

Pieces that werent in LDD but have to be used in the model:

Change this white gear to a clutch gear of the same size.

Change this piece:

Zblj's version:

Into this piece (Black):

Change this piece:

, Also made by Zblj

into a normal PF-switch and connect the wire to the battery box and connect the wires from the PF lights to the switch

Change the following two pieces:

, Made by Zblj.

Into:

Change

, by Zblj

into:

Add 4 normal engine blocks here:

and add the pistons too.

Add a M-motor here, so that the dark gray axle is in the M-motor

Connect the wire to the blue port on the Receiver

Add PF lights behind the following 2 pieces:

On both sides of course, so 2 lights at the front and 2 lights at the back. The two wires will be connected to the PF-switch

And finally push the red 2-axle through the axle-slots of the two dark grey pieces under it.

I didnt manage to do it in LDD.

It took forever to do so i hope someone finds it useful.

EDIT: Attached it didnt work, so here is a link to download it from mediafire. (104KB)

http://www.mediafire.com/?zlqdxn74ozdjwhm

Edited January 5, 2011 by M4X1994

[vmln8r]

Nice job! Do you know the top speed?

I'm wondering how well the two XL motors will work coupled together that way, as that forces them both to run at exactly the same speed -- I would wonder if one of them would end up doing most of the work while the other has a free ride. But I'm not sure whether this would happen or not.

I've had this issue when building vehicles with 2 drive motors - there doesn't seem to be an improvement (in efficiency) compared to using a single drive motor.

My Batpod uses a single XL geared 3:1 and reaches ~5.5 km/h. However my racing truck (of which I'll soon take pictures) uses two XL drive motors geared up ~3.57:1 (to wheels similar in diameter to the Batpod) and and reaches ~6 km/h, which isn't noticeably faster (then there's another bike I've just completed which uses an XL geared 5:1 and goes ~11 km/h on half-charged batteries ).

I think it is the slight difference in speed between multiple motors that causes this problem. Is the moral of the story to simplify and add lightness or is there a solution?

Edited January 5, 2011 by VMLN8R

[M4X1994]

Nice job! Do you know the top speed?

According to the Yellow lego speed meter its going at 5,40kmh max. But I have no idea how accurate that is.

[rgbrown]

Nice job! Do you know the top speed?

I've had this issue when building vehicles with 2 drive motors - there doesn't seem to be an improvement (in efficiency) compared to using a single drive motor.

My Batpod uses a single XL geared 3:1 and reaches ~5.5 km/h. However my racing truck (of which I'll soon take pictures) uses two XL drive motors geared up ~3.57:1 (to wheels similar in diameter to the Batpod) and and reaches ~6 km/h, which isn't noticeably faster (then there's another bike I've just completed which uses an XL geared 5:1 and goes ~11 km/h on half-charged batteries ).

I think it is the slight difference in speed between multiple motors that causes this problem. Is the moral of the story to simplify and add lightness or is there a solution?

There is a solution - add them using a differential. But that solution might be a bit fragile for 2 XL motors