100% Lego flight attempt

[Doc_Brown]

Ok thought that I would make a new topic, because that other one is getting a bit long in the tooth, and not sure how many people still read it, hehe, no offense intended!

This is my idea, that I'm pretty sure won't work, but I just had to try.

I believe this is as close as you can get being 100% Lego.

Unfortunately I broke 2 motors trying to straighten the axle between 2 props (Don't do that!)

I have spares, but won't be able to film now till this evening.

What are your thoughts on this design?

These little motors do pack a punch but have a limited lifespan of 200 pulls.

This model weighs in at 40 grams.

Edited June 29, 2014 by Doc_Brown

[rollermonkey]

Are those the pullback motors?

Does it work?

(And how much fun is it trying to hold three from spinning while winding the 4th?)

[LEGOGEL]

Is it proved to work?

[gifinim]

Very nice idea - I do hope you can get it on film soon!

[camaudio]

you could easily make a lego rig to hold it and wind all motors at the same time

[TinkerBrick]

Looks interesting - let us see some video footage.

[Rockbrick]

very minimalist....

[anton1678]

I still read the other one (I created it), but I agree, it is a bit long in the tooth.

Are those the pullback motors?

Does it work?

(And how much fun is it trying to hold three from spinning while winding the 4th?)

Does it work?

I've seen another pullback that flies using those props, but it didn't lift the motors up, only an axle.

I need those props, but they are worthless if only for the aviation thing

This model weighs in at 40 grams.

I have seen a model produce lift of 40 grams before, so I am watching this with interest

Lose the 'stand' made of the 4x1-stud plates, makes it heavier, and not needed to fly

[1974]

Would it be possible to use the more efficient propeller type?

There are several types of pulltback motors. I seem to remember a very tiny one with a good deal of power but I think it's only possible to attach wheels?

[Rockbrick]

if this does work - you could remove the screws and glue the backs back on - to save a few more grammes?

[1974]

That's modification of LEGO, if we down that route when do we stop?

[Doc_Brown]

Yes they are wind up motors found in the Shell series of small cars that could be purchased at your local petrol station. Sorry forgot to mention that.

I thought about that also looking at why the broken ones failed, and maybe increasing its power out put, is that still 100% lego? hehe

Sorry for the delay guys but had to get some more wind back motors so I can make the attempt with 4 brand new ones. :P

Video shortly.

[Doc_Brown]

Heres my attempts. hehe. And blooper.

Any suggestions?

[eurotrash]

I've a couple of ideas.

• You tried in one of the attempts to get the base of the copter off the ground by using a small stand. Make that stand taller to give you more clearance for the props to work because at the moment it's just sweeping the air away and not (I'm guessing) providing much lift.
  
• You might try making that central gap (between the four orientated arms) larger and use a controlling rod through that newly enlarged hole to provide guidance until the beast is airborn.
  
• Attach string to the top of the copter. Lift it off the ground (to provide clearance for the lower set of props) and see if it can lift itself once the motors are released. If it doesn't do that then it's not going to get airborn
  

Just my 5c worth!

[hrontos]

There is also may be a problem that top and bottom propellers "steal" the air each other.

What if you put all propelers on the top with 90 degrees offset? It looks like the pin should be able to hold both propelers.

What if you put it with some support structure on a kitchen scale? Will it show 40g less when the propellers are spinning?

[camaudio]

then you can remove the bottom pins and save a little weight

[SNIPE]

Would be good to synchronize the motors else the whole model will spin instead of directing the energy to make it lift.

[Zimix]

Nice idea.

I would try if you can to make 2 of the motor rotate in oposite direction. Not sure if the propeler are suitable for that. In order to avoid spining of the whole unit.

[Zerobricks]

You are having same problem as me...First the rotors are not mirrored, which means either you loose power with the whole model spinnnig around or you tilt them so they counter act each other, but you still loose power... If we had proper mirrored rotors we might have some real stable flight by now.

[Doc_Brown]

You are having same problem as me...First the rotors are not mirrored, which means either you loose power with the whole model spinnnig around or you tilt them so they counter act each other, but you still loose power... If we had proper mirrored rotors we might have some real stable flight by now.

Yes that is my most biggest problem, and anyone

There is also may be a problem that top and bottom propellers "steal" the air each other.

What if you put all propelers on the top with 90 degrees offset? It looks like the pin should be able to hold both propelers.

What if you put it with some support structure on a kitchen scale? Will it show 40g less when the propellers are spinning?

I'm not sure if they do "steal" the air, I thought they would help each other out, but a good point and will give it a go.

who attempts this kind of experiment. I will try to counter somehow when I hav the time.

Thanks for all the great suggestions guys, keep them coming and I will try them out soon.

[Rockbrick]

not sure ground resonance is going to affect something this small - but perhaps put both props on top (axle connector and a 3L axle) and offset them all by 90 degrees but mirrored

on each side in the video it sure seems to want to lift - would be interesting to see the change in weight on a sensitive digital scales

Edited July 1, 2014 by Rockbrick

[JM1971]

More wind back motors might do it, maybe bigger props, look into ground effect because you might be able to get it to hover instead of fly, nice attempt though.

Edited July 1, 2014 by JM1971

[Zerobricks]

Making Lego hover should be easy with RC motors....But really low hovering.

[Rockbrick]

Here's hoping someone makes a Lego ekranoplan, manages ground effect and hence makes the first all Lego flight

[Captainowie]

Here's hoping someone makes a Lego ekranoplan, manages ground effect and hence makes the first all Lego flight

Yes. That's the only way it's going to work, if at all.

A 'copter has to accelerate itself at 9.8 m/s/s (effectively) just to get liftoff. A fixed-wing craft only needs a fraction of that. Something that doesn't need to break free of ground-effect can survive with much shorter (= lighter, simpler) wings.

I'm still doubtful that you could get enough thrust even then, but I just can't see it working any other way.