Help me make a flying helicopter!

[hrontos]

I just got off a 747 yesterday with a Technic friction pin in my pocket, so I have already made LEGO fly.

:laugh: So now we know a studless LEGO can fly. What about studded versíon?

[Bob De Quatre]

:laugh: So now we know a studless LEGO can fly. What about studded versíon?

When I was young I've thrown some Lego by the window, At that time there was only studded models, and I assure you they flew...

It may be obvious that no Lego model will ever flew on it's own , but practical research is always interesting and fun

So the flying helicopter may be a dream, but what about an hovercraft? Maybe there is something fun to do in that way, and thus what Zblj does is interesting.

[kieran]

When I was young I had a flying helicopter toy that had a pivoting boom, on one end was the heli and the other a counter weight. The controls allowed you to throttle the main motor to gain height and rotate the boom to move forward or backward. not real flight but was fun and allowed the toy to get up a fair bit of speed, this sort of assisted flight will defiantly be possible with pure Lego, just a shame that real flight will not, not with that is currently available anyway.

[Tamas Juhasz]

I fear this one is a bit controversial. While Zblj's machine is fully self-contained except for a power source, some people may point that you just made a couple of propellers that detach from the motors. I mean no offense, but probably many people see a huge difference between your creation and Zblj's one.

No problem, but you don't understand what I wrote: "I know, it's not an RC controlled helicopter" ; "I just wanted to prove that Lego can fly from it's own power." That could do it, this is fact. And the most important that it's not a single propeller, which take off. It has a body(ok, small ) and two propellers. I never seen(of course, that doesn't mean that there isn't) an other moc without cables, wich is more than a single propeller, AND can rise up and fly.

Just for the record, this attempt was 4 years ago

That's only a propeller. Many of us had succesful experiments with a single propeller. My first experiment was also with a single small prop and the 8L axle about 6 years ago with one pull-back motor.

Edited January 9, 2013 by Mbmc

[DarkShadow73]

Would be cool if you could get a motor strong enough to make the 9396 lift off

[Zerobricks]

I've been thinking... Since the secondary rotor is not the same as primary (blades angled at some angle in order to mirror the propeller), they dont create same lift/drag. Also using a coaxial variation proved too hard for the secondary motors (3 gears eat some power). So what i think might still be a feasable option is to use 4RC motors and make a quadcopter. Why? Becauset this way the weight of the entire thing is spread between two pairs of normal pitched and mirrored piteched propellors, therebye totally canceling all varations (i think...).

What you guys think?

[AVCampos]

I was thinking of doing exactly that, a quadcopter, come time ago, but never took off (pun intended) from the project stage... Before doing that, you might want to try building a tandem helicopter like a Chinook, as the structure connecting the motors can be smaller and therefore lighter.

[Zerobricks]

I tried that, but the difference of force created by the mirrored and normal proepller proved to be too big. Either they create same force to keep heli leveled, but that the drag is different casuing the thing to wanna spin, or you create drag, but than one end has less lift than other.

[dhc6twinotter]

Quad rotor sounds good. Have you tried using intermeshing rotors like this:

Might be difficult to do with those wide blades though.

[Zerobricks]

Thats another option, but that means the speeds have to be snchronized, bring back the problem of mirrored rotors generating different drag ratio, meaning whole thing will spin out... Gonna see if there is a way to mechanically make the mirrored rotors to be as same as possible to non mirrored ones.

[Conchas]

In the sequence of the experiments that I shown yesterday and with the advent of AR.Drone, the natural next step is exactly the quadcopter, which should solve a lot of problems by the concept itself.

Although I did not pursue yet the objective as still believe in very, very limited success.

This even if you have mirrored LEGO blades for the counter rotating setup, or manage to mount them in such way with the minimum parts possible.

Since the goal is to make some kind of pure LEGO contraption fly, I would not consider any over-voltage setup. Then as demonstrated you will need a BB for each motor. Four of them will be too much to lift and the flight will likely be always tethered...

Not to mention there is no simple way to implement the necessary rotors control with LEGO parts, like done by AR.Drone electronics.

Most promising would be the usage of 6-blade rotors, but as tested also, the BB do not cope with the requirements.

That said, I would dare to add, that I will prefer to play with one AR.Drone device.

[hrontos]

Gonna see if there is a way to mechanically make the mirrored rotors to be as same as possible to non mirrored ones.

Do you have also some results with some simplier shapes like plates or panels? May be it works also with them and they will be easier to mirror than the blades.

I presume it can be very complicated to mirror those blades since the rotors have provide equal lift force and at the same time also equal torque so that they really compensate each other.

Edited January 9, 2013 by hrontos

[Zerobricks]

I think the key here is to sucesfully mirror the rotors to a degree of precision. Only than there is chance to have enough balance for any rotor placement, tandem or quad.

[SkyrateShadowStorm]

@ZBLJ, Your tests are pretty awesome. I'm glad to see there are still a few true LEGO Masters out there who know LEGO can fly.

I think the Quad-rotor may work. The Tandem won't with those blades because, like you said, you can't get even lift and drag on both rotors. Tandem also requires both motors to be spinning at the same speed(so for Tandem tests you need to have only one power control knob feeding both motors).

As for the Quad, it should be more stable, but I'm not sure how well the lift will work. Quads require two sets of counter-rotating rotors perpendicular to each other.

Y

X-----X

Y

Y is Clockwise

X is Counter-Clockwise

The counter rotations, assuming all 4 motors are spinning at the same speed, should negate all torque.

The potential problem I see would be the fact that for those rotors to be turned around to counter-rotate, it drastically increases the size of the leading edge of the blade. The counter-rotating blades would have a lot more drag.

I just played with those blades in LDD and it's possible to nearly mirror them, the hard part being creating the angle we need with the required strength.

EDIT: In re-watching your coaxial video I see that you've angled them like this.

Edited January 9, 2013 by SkyrateShadowStorm

[Zerobricks]

None yet.

Here's my next flyable machine:

All i need now is 2 more PF extension cables and more batteries to feed the 2 hougry motors.

Yes i already did that, but the angle difference is too high.. Need to adjust angles to match.

[SkyrateShadowStorm]

Oh, right. I remember seeing that picture, just didn't notice the pitching pieces on the left rotor.

Make sure your normal rotor has the same basic weight of additional pieces, otherwise your anti-pitched rotor will be heavier and thus will require more lift or will fly lower(or spin slower).

Another thing is to make sure you are activating both rotors simultaneously, with the same control. They need to spin at the same speed otherwise the torque of one will knock it off balance.

I know you've already done a lot of tests and are probably aware of most of the aspects I'm mentioning but sometimes hearing them again can bring up new ideas or variations.

[Zerobricks]

Okay, i think i managed to mirror the rotor so the angle is very close to the normal one. Now i only need 2 more RC motors.... Any ideas where to get them cheap?

[SkyrateShadowStorm]

The 5292 Buggy motor? Eesh, good luck. ~$32 at Bricklink (http://www.bricklink.com/search.asp?itemID=37545&colorID=11) Maybe better on ebay.

Maybe you could mount one on the top and one on the bottom in the center of your quad and use a driveshaft to have one motor power two rotors, one for each axis?(top spins clockwise, bottom spins counter-clockwise?)

Or alternatively try the tandem again until your other two motors arrive.

[Zerobricks]

Just tried my mirrored rotor with some upgeared Xl motors. No matter how precise i manage to get the angle of the mirrored prop, its still not as efficient as the unmirorred one. The blades are just not totally same, one edge has more curvature than the other. This caused the test frame to slightly rotate in one direction, meaning a tandem or a quad would have same problem...

So ATM i am stuck....

About driveshafts. Rotors require quite some torque, and the frame would start to bend by the torque of driveshafts, meaning the rotors would blow sideways... Also gears loose power.

[camaudio]

why dont you just reverese the direction of the motor and mount the blades normal?

you can even flip the motor upside down compared to the other one

[SkyrateShadowStorm]

@CamAudio, You have to have the pitch of the rotor blades be correct. Just reversing one motor would causing it to pull the craft down instead of up.

@ZBLJ, Quad may still work, you just may have to use different speeds. I.E. X at 75%, Y at 80%.

I've done a fair bit with rotor and gear testing with technic and know what you mean. The 5292 is not hospitable to gearing due to its high rpm but very low torque. I think XLs may be able to drive the driveshaft and then be upgeared or vice-versa. Using round gears you can get a 1:3 ratio with one assembly, using normal(or as I say, 'hard') gears, you can get 1:5. The XL spins at around 146-214 depending on your voltage. That could get 438-642 or 730-1,070 rpm, with decent torque(easily enough for those blades).

Do you know your target RPM?

[vmln8r]

Now i only need 2 more RC motors.... Any ideas where to get them cheap?

Direct from Lego, they should be cheaper (this is the 2011 price):

Element #: 4177239

RC buggy motor (sets 8366, 8421, 8376, 8475, 8287)

£10.72 (GBP)

[Rishab N]

I just got off a 747 yesterday with a Technic friction pin in my pocket, so I have already made LEGO fly.

[Brickend]

Could two of the blades be under the motors and two on top (conventional) in order to flip them?

[Nazgarot]

Hi,

I have an idea you could try for a 2 rotor counter rotating construction with only 1 motor. It should have more lift pr motor, and it should be easy to put two of them together to make a quad... replace the red parts with a buggy motor...

And the .lxf

-ED-