Sariel

Forget the RC models, I still can't get over the price of a simple pneumatic airtank. It appears to be one of the most valuable pieces of plastic ever produced by TLG.

I think it's definitely not a copy as the two are built at different scales (compare the wheels). It's a nice comparison, anyway.

Could you please provide pictures or links? The builder is a new LUGPol member, so I would like to know if this is not his original construction.

Yes, I guess so. I was thinking of selecting the motor's output.

But it works with a single motor too, and besides the extra motor adds twice the power, it's not like it's a dead weight. I'm a little confused as to why this concept appears so new and unclear. It's a gearbox that can change the speed/torque proportions by 35% while having just 5 gear wheels - Lego gearboxes rarely get more efficient that that.

Well, it would be my guess than if you can switch between output that has more torque and another that has more speed, then it can work as a gearbox. Regular gearboxes rely on their internal gear ratio, this one here relies on the gear ratio inside the RC motor.

... and less torque, I missed one word, ouch.

Not at all. That looks very interesting, I think I'll get it and test it, thank you.

They turned out to be most efficient in my tests. When choosing a propeller, you have to look for balance between the small ones, which are inefficient, and large ones which require large torque. I believe these particular propellers are very efficient because they're relatively large (9 studs diameter) and have blades of little surface (no large torque required). And while they come with two blades each, you can easily combine them into 4-bladed units. My research on Lego propellers has been independently confirmed by another LUGPol member, who has been running plenty of efficiency tests. They appear to be completely flat on the image. I mean, the shape of blades doesn't allow them to push water forward or backward. I'm afraid this is one of the Lego propellers that are made just to look nice. But this is still not as bad as certain Exo-Force turbine: http://www.bricklink.com/catalogItem.asp?P=53983pb01 It's big turbine with plenty of blades, and it looks very promising until you notice that the inner and outer ring have blades set at opposite angles to each other. It could be quite an interesting piece, but someone at Lego decided otherwise :)

This was done by another LUGPol member years ago:

It's no more than 3 meters outdoors in the open. Which is why I've used the PF speed dial remote - it makes the motors keep going even when the IR link is lost. This way, I was able to make the boat go in large circles - I made it start to turn, it went far away from the shore and kept turning even though the IR link was lost, until it came back close enough to be within the range of the remote. I would have to think of a reliable way of measuring it first. I see no pros, only cons of using this motor. Namely: 1. it's much less effective that the propulsion system I've used, 2. the rudder is tiny and would require a large external control mechanism, 3. I had some trouble with algae getting tangled in the propellers and while it was not much of a problem with the propellers I've used, it could damage this motor.

You make it a little hard for us to answer you by writing like this. Proper English would let us avoid many misunderstandings.

Oh, that is very interesting.

I know, I know, and I didn't even catch any pretty lady in the background this time :(

I gave him my meanest look, just as a precaution.

Shall we? Description: http://sariel.pl/2011/05/quadramaran/ Photos: http://www.brickshelf.com/cgi-bin/gallery.cgi?f=474198 Hulls: http://www.bricklink.com/catalogItem.asp?P=50821c01 Propellers: http://www.bricklink.com/catalogItem.asp?P=2952

It's allowed and, in fact, popular in Polish Truck Trial. Atr's truck uses it, and I think TT's one has been using it for a while before he turned to controlling one NXT brick with another NXT brick.

Erik is the ultimate crane master, no doubts about it :)

Thanks guys. I forgot to mention in the video that it took 4 hours to build.

I've seen that lady closely and my bet would be on the latter :)

Well, it was either worn axle pin, or the wheel was attracted to the blonde lady on the bench ;)

You forgot to mention that the "extensive discussion" focuses on the blonde lady who appears sitting on a bench in the video ;) Kudos to you, Dave.

Last time I checked MOC stood for My Own Construction, not for My Copy Of Mahjqa's Work.

Thanks. And left from the yellow Jeep, do I see a piece of Humvee? :)

I ran the Lego V8 at 2000 RPM and everything was fine. It sounded cool too.