A Vtol made from Lego pieces

[EyesOnly]

Well i've begun work on what i first thought to be an wild goose chase. I wanted it to be done but didn't know if it would work. Some searching in this forum lead me to think otherwise. Or to be clear the design i had selected for a Vtol had already been tested here with variations so know i know it will work.

The plane will be very simple at first featuring a thin body with 2 beams going out in a crosslike fasion to make wings. Equiptment is as follows:

Lego beams and plates as body
2 futaba standard servos
2 370 ST motors with GWS 10/4,7 props
jeti rex 5 rx
jeti jes 020 esc
etec 1700 shp 7,4v

I use those servos as i had bought them earlier but that plane would have been alot bigger. This was planned before i realised that i can't fly a MPX Magister so any other kinds of exotic ideas was put on hold.

Since then i've bought an Easy Star and a Protech Butterfly and now i feel like i know enought about flying to take on this project again. I didn't want to say anything before knowing what non Lego builders think but after building the frame and mounting servos i feel like i can do this.

The weight on the model is so far 400 gr, something that prolly will increase since i don't know how i will be fitting the motors and so on but i know i've got enough lift, the only question is how controllable it'll be. Luckly i can't fly helis so any design defect will not be revealed. :)

BTW considering the complexity i've seen on some models, why don't you just build the fullscale version while you're at it. Surely it can't be that hard. The servos are set up to enable hover so the pods tilt slightly back and forth but not to 90 degrees. I've since realised that real ones don't work like that but for now i've happy to hover. It's not like i could fly it at home anyway.

Eventually i might add control surfaces but as i said this plane will just hover for now. Maybe one day i'll also add wings or make a fixed wing plane but i've more interested with Vtols.

Lego just like model planes are built by people of all ages so noone is ever to old for any. ;) Pics will come when i'm done.

[rdresch]

Good luck on your project. These things can be a lot simpler if you only intend to hover. It's when you you try to be both a plane and a heli that it gets really complicated. I know nothing of the lego system so I look forward to following this interesting project.
Rudy

[EyesOnly]

Just got home after going to the postoffice and picking up the package. 2 km back and forth with snow on the ground in a storm. I'm beat. Anyways i thought i might answer i question that might come up: Why not use Lego motors? The reason is simple, power to weight ratio. Those motors are designed for ground vehicles not airplanes and even if the thrust was there you'd still not have any props since those aren't made for lifting anything either, they're just for looks.

Therefor i went for rc gear since it is made to fly. If you want to know some data about Lego motors just check out this link. (http://www.philohome.com/motors/motorcomp.htm)

One thing i find strange is that no one has thought of combining these parts like this before. I recall seing a robot wars robot once but no airplanes. And i've seen some amasing stuff yet the only fliers i've seen are gliders. The main reason for this is because most think that you must have rounded wings to fly but this of course isn't true.

It's not funny to have to relearn something is "basic" as why planes fly when you're my age (i'm 25) but without that knowledge i wouldn't have a chance of making my own planes. One day i plan on building a copy of the Protech Butterfly in the same size out of Lego axles. They're about the same size as the rods so it should work. Now though it's time i get my lazy butt away from the computer and start to build.

[EyesOnly]

Thanks rudy. I'll post back soon i hope.

[EyesOnly]

Ok i've hit a bump. Just noticed that i only got one motor. :mad: :censored: I emailed the store so i hope they'll send the other one soon but according to their site they're closed tomorrow. Hopefully someone will still be there today and read my message.

Anyways since all other parts was there i suppose i might as well start on a fixed wing aircraft now. I'll try the butterfly look and see what happens. But for now i'm gonna find out if The Village is a good movie or not. I'll post back here when i've done something worth talking about. ;)

[EyesOnly]

well i have built a "plane" but after thinking about it i decided not to show any pictures of it. Why, because it's a monster weighting in at 740 gr. It was to heavy to even move on a slope. Indoors it was moving but outside on a small incline it just wouldn't move.

I'm gonna rebuild it after getting some miniservos. Iäve learned some lessons on wingdesign now. I used sandwish wrap wrapped around Lego axles and then fastened with tape. This seems to work quite well be the wings can't be very big without flopping. Next i'm gonna try cardboard instead and use beams the don't bend.

The vtol is still grounded due to the missing motor. I'm gonna keep reporting about any Lego plane i make in this thread, vtol or otherwise, if that's ok to keep from making to many new threads.

I still feel like this can be done, but weight will have to be low. While this plane could ROG, tossing it might have worked but i didn't feel like doing that. I should prolly surrender my plans to make it indoor friendly too since the final size might prevent that. But as long as it's part Lego pieces and flyes it's still what i wanted.

[rdresch]

EyesOnly,
Weight is critical. You need a minimum thrust of 1.5 times the weight to make it work. This means a lite build, and lipo batteries and brushless motors. Good luck and please realize this won't be easy or cheap.
Rudy

[EyesOnly]

1.5 times is that say 150 gr of thrust to a 100 gr plane. If so then staying under 600 gr for the vtol should be ok right?

As for the regular plane i might end up with a similar weight for starters. I've got a lipo but didn't feel like using it on such an experiment so i'm saving it for later. Those 50 gr of weight between the lipo and what i'm using would be nice to not have but i don't want a lipo ending up in a pile of snow.

Why must brushless come up everytime lots of thrust is needed? Surely there must be a way to solve it without that? I'm going to build my plane even if i have to use cardboard and balsa to do it. At worst the plane will have to be thrown like my Easy Star which i'm getting quite good at launching.

I now have some BMS 371s which will be fitted tomorrow. The cg was way off so i tried correcting it with a weight from Lego trains under the prop hence the large weight. I'm gonna go over the whole plane before i try again. I'm sure i there's weight to be spared now that i know what to do. Hopefully i'll have the other motor tomorrow to i can continue on the vtol.

[rdresch]

What is the thrust from the props? brushless is more efficient, hence you can use smaller batteries and reduce weight.
Rudy

[EyesOnly]

True. The thrust is supposed to be 470 gr per motor with the above props drawing 8,5 Amps. Theoreticly that should give me 940 gr of thrust with 2 motors even though it prolly wont be as much. The figures are based on the battery i mentioned in my first post but i'm using a 7 cell nimh for now.

One thing that still worries me though is how i should wire this. I first thought parallell but i remembered that series makes for less current. For now i've soldered the wires together but when i use both motors i've planned on using mpx plugs on them. Correct me if i'm wrong but to be in serie one cable should go from plus on the esc to minus on motor 1, then from plus on motor 1 to minus on motor 2, then from plus on that motor to minus on the esc. Or is it the other way around.

[rdresch]

I don't think you want to do that. You' probably burn up motor 1 and the controller. Wiring batteries in series increases voltage, but if you wire your motors in series all of the current that motor 2 is drawing will try to go thru motor 1. that's not good. wire in parallel. Your speed controller must be large enough to handle the amperage of both motors at the same time. Say 25 amps per motor x 2 = 50. These are expensive. try 2 25 amp speed controllers, or whatever your max draw would be. Increasing the voltage from the battery pack is another solution. This will reduce amperage but will your motors handle it? My guess is that 2 controllers at the correct amperage and battery packs at the correct voltage for the motors would be the best solution. I'm no expert on this, so double check on the elect motors forum. They will know. Wait till know for sure, there is a lot of smoke hiding in those wires. By the way if you have 2 6v battery packs and you wire them + to controller - bat 1 to + battery 2 and - battery 2 to controller you will increase voltage to 12v. this gives a lot more power to your motors IF your speed controller and motor can handle the higher voltage.
Rudy

[EyesOnly]

I have a jeti jes 020 so i should make it. Don't tell me i need 2 esc as well. So parallel is the way to go. I'll try something tomorrow.

[EyesOnly]

I had written a post but forgotten to post it so when i refreshed the page it was gone so i'll write again. This project has been put on hold or canceld if you will. After completeing a design that seemed good and yet failed to get it of the ground i rebuilt it using fixed rotors and it finally lifted. Unfortunatly only one prop lifted and the other soon hit the ground. Surpricingly it only started unscrewing itself.

Anyways i realise that i need to balance the props. This would recuire 2 esc and prolly b.less motors. Therefor i've began work on a conventinal airplane. It will have both motors and prolly look kinda like the MPX Twinstar, at least that's what i'm using as guide even though i'm planning a weight around 500-700 gr and a wingspann of 1 meter.

I measured the electronics and it weighs in at 300 gr so i'm not gonna get under that weight and will therefor aim to make a large plane that hopefully can ROG but otherwise i'll just throw it. I'm sticking with LEGO pieces but will use cardboard as cover material for the wings and maybe just cardboard for rudder. It's not like modelplane rudder consist of much more than that and they work just fine.

If this all fail which it feels like now i'm gonna buy a CAP 2 T3D Wild Beast since it uses the same motor. Perhaps i should just build something in depron but i haven't found any 2 motor designs. Actually i haven't found a single plane that isn't 3d. If anyone knows any depron that are easy to fly and can use the motors i have please let my know. Since many people build depron planes from scratch mayby i should to and i will if i can't get this to work.

[rdresch]

Sorry it didn't work out, but it's not a failure. You learned something and had some fun while doing it. It's all about the journey, the destination is just another starting point.
Rudy

[EyesOnly]

I just realized just how crappy Lego pieces are when it comes to making planes. Tried making a wing using axles and then cover/reinforce with cardboard. It got to floppy. This could have been because i hung the motors in the wing. A single motor design would have been better but i wanna use both motors.

Now i've given up on this and will use the pieces in another plane such as the priviously mentioned Cap. From here on it's all depron if i build from scratch. I will however try my luck on RC ground vehicles but then i would have to get a 40 mhz radio system which doesn't feel needed right now.

While checking a swedish forum i heard many bad things about the motors and also about the CAP. I'm starting to feel like i made a really bad investment. Oh well.