[WIP] Flying Brick

[Lucio Switch]

I don't think that it will fly, but I'd love to be proven wrong!

I tend to be a purist, I can understand the elements substitute to PF, but, for my personal opinion, glue and Lego in the same sentence sounds very bad.

Anyway good luck and I hope you surprise us!

[Tommy Styrvoky]

It will be interesting to see if the model will be able to withstand flight, since the wings are only structurally supported by one layer of technic beams. if it doesn't fly, it will still be cool to see it taxi.

[Good old Lego builder]

I wish you the best of luck. It is a really nice project. Surprise us!

[Carsten Svendsen]

Now this is interesting. I recently started building on my own plane again, as it seems my recent MOC kickstarted my lust to build again.

As others have said, I don't think it's going to hold in the engine compartment as there's too much vibration and the glue and bricks will simply come apart. It depends on the type of glue you use though. I know that there exists some glue that actually melts plastics a bit when put together.

Though bricks will make it much stiffer and solid, it's going to be a lot heavier. My plane also weighs in around 5 kg but it's a lot bigger in comparison. You need some good reinforcement on the stressed parts.

I'll be keeping a close eye on this thread

[whale2]

Poor man's airfoil test bed :)))

Going to secure it on car's roof and drive around. Luckily I have sliding sunroof to monitor this thing.

[whale2]

...

My plane also weighs in around 5 kg but it's a lot bigger in comparison.

...

I've found some of your specs :)

http://www.eurobricks.com/forum/index.php?showtopic=73936&st=50#entry1486060

According to this, yours have wing area about 23 dm2. Mine about 31 dm2 with wingspan of 1648 mm.

[_Cookie_]

Wow, really nice project there

as rc plane pilot, i would be worried about the Motor mounts and especially the vibrations from the Motors (i hope you used a somewhat elastic glue and not "stone hard" CA glue).

Anyway, good luck with it

And... as you stated here: http://www.eurobricks.com/forum/index.php?showtopic=90916&st=25#entry2056796

Do ALL your servos only have 8 Ncm? In this weight class you should get servos with at least 40 to 50 Ncm

Cookie

[Tommy Styrvoky]

Going to secure it on car's roof and drive around. Luckily I have sliding sunroof to monitor this thing.

Looks like an interesting setup, hopefully it doesn't designate, causing a barrage of lego bricks to slam into unsuspecting cars behind you... Good luck, I hope it holds up and works properly.

[whale2]

...

And... as you stated here: http://www.eurobrick...25#entry2056796

Do ALL your servos only have 8 Ncm? In this weight class you should get servos with at least 40 to 50 Ncm

Cookie

I was talking about force, delivered by miniLA.

But frankly, I can't get it. My different rough (and not so professional :) ) calculation shows that for aileron of chosen size (24 mm x 192 mm) at speed of 80 kph and deflection of 45 deg the deflecting torque on the aileron hinge would be somewhat from 2 to 4 N * cm. However, I pretty well know such recommendations about servos :)

What am I missing? Is that much force is being lost in linkage? Is there so much over-provisioning? Assumption for operation at airspeed of some 200 kph?

Please enlighten me :)

Edited November 19, 2014 by whale2

[Kelkschiz]

Dear Mr. Whale,

You have been at this for almost a year now! You are seriously testing my patience. I think we need to have a little chat about your work tempo. I mean seriously, we are talking about flying LEGO, not launching it to space. Please get back to me in a month with a working prototype or i am going to have to reconsider your future at this forum.

Yours,

Kelkschiz

Member of the board of EB

Edited November 19, 2014 by Kelkschiz

[_Cookie_]

I was talking about force, delivered by miniLA.

But frankly, I can't get it. My different rough (and not so professional :) ) calculation shows that for aileron of chosen size (24 mm x 192 mm) at speed of 80 kph and deflection of 45 deg the deflecting momentum on the aileron hinge would be somewhat from 2 to 4 N * cm. However, I pretty well know such recommendations about servos :)

What am I missing? Is that much force is being lost in linkage? Is there so much over-provisioning? Assumption for operation at airspeed of some 200 kph?

Please enlighten me :)

I think those recommendations fit very well. To be honest, anyone i know does not calculate those values (including me, of course ). It are values that are combined to a median by many rc pilots over time.

There's also that "rule" to have 200W/kg on your engine IF you want to go vertical, or only 100W/kg if it's a non acrobatic, aerodynamic glider.

I may have not as much experience as other rc pilots, but I have a very good example that suits this case very well:

Styrofoam plane with oversized rudders, 500g weight, 75W Motor and 7.5 Ncm Servos.

The plane may reaches 40km/h and is a bit too heavy for its design.

The servos are really the minimum here.

I saw it several times, that the elevator was pushed down a little while going up with full-speed (against some wind).

Then again, some may say... uh that's your foam that bends in the wind... (in my opinion that part is very rigid. You'll notice the difference between a "sponge-like" and "rigid-but-not-enough-power" model, when YOU fly the plane.

So... please, at least double or triple your 8 Ncm

Cookie

Edit: The sad truth about servos (and i guess that counts for everything today...) is, that they don't deliver what is in the datasheet... It's the best to assume that they reach about 10% less than stated.

Edited November 19, 2014 by _Cookie_

[whale2]

...

So... please, at least double or triple your 8 Ncm

Cookie

I don't see a way for this yet. Perhaps I'll arrange some tests with current setup at first.

[TheNextLegoDesinger]

if you make little wing tips on your big wings you're plane is going to have less drag. My technic teacher learned me that it is 20% more fule eficiant

[Boulderer]

if you make little wing tips on your big wings you're plane is going to have less drag. My technic teacher learned me that it is 20% more fule eficiant

True as this, I think that the aerodynamic efficiency of the main wing really needs to be optimised before the winglets will have any significant affect.

[whale2]

Well, I really think that optimizing drag is little out of my scope now :) There's no way for this thing to have any good performance. Point is to not break down, accelerate, not break down, take-off, not break down, climb a bit, not break down again, make a circle, approach and land and finally not break down :))) Then we can turn back to optimizing :)

[Boxerlego]

Its awesome to see the build up on the lego plane at best will be a good model of one but I don't understand. Why not build a more practical design instead of one that seems it will fall apart mid flight. I can make a LEGO flying plane right now but it wont be 100% LEGO nor will it have a radio control flight but it will with out doubt its going to Fly because its all ready proven to fly. When I get around to it I will post some pictures of my Pneumatic Engine Planes.

[TheNextLegoDesinger]

i think you really should make wingtips. you're plane depends on it. if you do it will fly, if you don't it won't

[Rockbrick]

like the wright brother's plane - they were happy it took off for a few seconds... then they made some aerodynamic adjustments (lost some weight etc..)

[Boxerlego]

Here is the pneumatic engine plane Im talking about, I had three of them one broke. It is capable of flying over 100 feet and can fly high. Watch this Youtube video and imagine if it was made of LEGO bricks. Now think about this if the brick plane crash landed in the street or on a major road would you want the kids going in the street picking up the remains of what is left of the flying brick LEGO plane. That is just one scenario that could happen. That is why LEGO plane must be made of the highest quality to stand up to the rough impact landings so your not left searching for little parts scatted around on the ground where ever that maybe, could be on a roof it is a plane after all.

Some pictures of the box. Click on picture to enlarge.

Edited November 25, 2014 by Boxerlego

[whale2]

(Almost) done with wings and flaps/ailerons:

Sorry for poor pictures - it was a late night :)

And this is how the whole thing looks like:

(Flaps removed here, as they need to be corrected a bit)

CG is a bit out of desired point and front strut happened to be shorter than needed. Still much to go...

And, well, something about the tests :)))

In fact, (and this is rather expected, why pretend?) test bed is far from perfect. Friction is too high when exposed to drag force. I will probably refactor it with wheels or something and try again.

There is *some* lift, but I can't be sure yet if it surpasses a checkpoint (by compressing shock absorbers @60kph, which is kind of predicted by some simulation software)

That's all for now.

[M_longer]

And this is how the whole thing looks like:

And you really think that it will fly? How much does it weights now, 2kg?

[whale2]

And you really think that it will fly? How much does it weights now, 2kg?

No, just going to film very expensive crash video :)

[JGW3000]

Regardless of whether is works, the build is epic. Looking forward to the videos.

[HorcikDesigns]

In the moment I saw the canopy, I have to say, that aerodynamic friction is going to be your main enemy in this outstanding, but utopic try to build something so complicated...

However, good luck... ;)

Edited December 8, 2014 by Gzzig

[whale2]

In attempt to find CG:

Regarding high drag - there should be plenty of thrust - 3 - 3.4 kg at full throttle, if motor/prop specs are right. (Motor test bed soon to come) As it was said, this thing is not expected to be efficient.