Carsten Svendsen

Antonov AN-140

137 posts in this topic

@ Carsten Svendsen: The carbon rods help a lot in the wing stiffness. The 1.5-meter (4.9-foot) wingspan is HUGE! *oh2* Have you attached the propeller assembly onto the engines yet, to see if the wings can handle the stress when they are spinning at full power?

RA-41254-_PlanespottersNet_301760.jpg

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@ Carsten Svendsen: The carbon rods help a lot in the wing stiffness. The 1.5-meter (4.9-foot) wingspan is HUGE! *oh2* Have you attached the propeller assembly onto the engines yet, to see if the wings can handle the stress when they are spinning at full power?

RA-41254-_PlanespottersNet_301760.jpg

Oh yeah, they can definatly handle the stress of the propellers spun by the large motors. I think they're quite stable and doesn't come apart easily. Mind that the LEGO pieces are going to be pushed upwards so the wings will not come apart in the joints by the panels.

I dunno how much force a real engine produces but I'll assume that my wings will hold their ground :)

Nice picture

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This week, I've been working on getting the landing gear to work. The actuator controlling the nose wheel was making a lot of trouble for me and its angle was too horizontical so I had to do something about it

j8R5FKK.jpg

I've added pneumatic to raise and lower the nose wheel instead and I've also added a mechanism to close the nose wheel hole, also controlled by pneumatic.

You can see all of that in this video (Watch in full screen or else you won't be able to see anything - and HD)

And if you wondered why I couldn't split the liftarms by the nose wheel it's because I ain't got enough room to play with and I ain't got Bob Hoovers schematics (Which is an awesome work).

Here are some pics of the internal functions:

iUDwxKo.jpg

WiBdd0Q.jpg

BdTBPDf.jpg

vUjb0Vl.jpg

qzeqYNP.jpg

Oi61x1y.jpg

6VVAxL4.jpg

Now I just await the mini pump ordered on BL and I've also ordered a mikro motor to experiment with the wing flaps since the axles and perpendicular joints causes to much play.

If you've got any questions just ask.

Edited by Carsten Svendsen

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Did you figure out anything regarding the flaps? I guess you could use a long beam in a 90-degree fashion, and force the flaps down/up that way.

tn_img001.jpg

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Did you figure out anything regarding the flaps? I guess you could use a long beam in a 90-degree fashion, and force the flaps down/up that way.

tn_img001.jpg

Oh, I haven't looked at that yet. I really should get going though.

I think your solution would work nicely enough, I just have to find a suitable spot for the motor controlling the flaps. If you didn't notice, the flaps are not in a horizontical line, but points upwards which makes at a tad more difficult.

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How many PF IR channels will you need for this?

What have you considered for a covering? (industrial heat shrink plastic may work well)

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No, atm I'm very busy with school work and I won't continue until after christmas

I didn't know it was possible to get heat shrink in this size, I'll look into it. It'll surely be the best option if it's possible

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Hello all :). I registered today, just to say, that this is totally awesome and i'm following it :D

I am not a fan of lego, and haven't built nothing since i was a kid. But i am an all time aviation lover, and a humble Pilot Student. To all the people saying that this machine won't fly.

The physics that are behind powered flight apply in a very similar way to any aircraft, regardless of size. Still, you HAVE to be wary of the weight, for with that wing profile (shape) you get a small wing area, so the plane will either have to be very light OR fly as fast as it's regular size counterpart.

If he gets:

a) The correct shape and angles of the wings.

b) No play in control surfaces

c) Enough structural rigidity as to prevent excessive wing flex under positive G load

d) A good CG position

e) Scale weight in relation to the real-life counterpart. 28.59Kg (about 63 lbs) is the theoretical maximum: square root of (weight of real life plane / scale). but for good results you shouldn't exceed half of that (14 Kg or 30 lbs) because if everything was scaled you would need 91 lbs of thrust wich i doubt two props that small can provide.

I, as an aviation lover, and pilot student, have faith in that this machine WILL fly as long as Carsten manages to bring the model to the above mentioned conditions, wich i'm sure he has the ability to do.

Cheers :)

Edited by ap0r

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Hello all :). I registered today, just to say, that this is totally awesome and i'm following it :D)

I am not a fan of lego, and haven't built nothing since i was a kid. But i am an all time aviation lover, and a humble Pilot Student. To all the people saying that this machine won't fly.

The physics that are behind powered flight apply in a very similar way to any aircraft, regardless of size. Still, you HAVE to be wary of the weight, for with that wing profile (shape) you get a small wing area, so the plane will either have to be very light OR fly as fast as it's regular size counterpart.

If he gets:

a) The correct shape and angles of the wings.

b) No play in control surfaces

c) Enough structural rigidity as to prevent excessive wing flex under positive G load

d) A good CG position

e) Scale weight in relation to the real-life counterpart. 28,59 Kg (about 63 lbs) is the theoretical maximum: square root of (weight of real life plane / scale). but for good results you shouldn't exceed half of that (14 Kg or 30 lbs) because if everything was scaled you would need 91 lbs of thrust which i doubt two props that small can provide.

I, as an aviation lover, and pilot student, have faith in that this machine WILL fly as long as Carsten manages to bring the model to the above mentioned conditions, which i'm sure he has the ability to do.

Cheers :)

The weight will always be a problem concerning airplanes. I believe that it weighs approx. 6-8 kg as of now - I need to purchase a luggage weight in order to be certain. Since the airplane is almost done and minor details are in need of a fix I don't think it'll much heavier than it already is. Of course the batteries motors and propellers will add the weight a little, and that's inevitable.

BTW, I'm no pilot and I know nothing about part names, but I hope you get the idea.

a) This has been the big hassle for me and I pretty much spent more than half of the total time on the airplane, making the wings, rudder and what not. I won't be able to achieve complete aerodynamics (obviously) but I can get pretty darn close!

b) This is a big factor for sure. As of now, there's way too much play in all control surfaces. I still need to rebuild the tail flaps, so in order to eliminate play as much as possible while making sure there's enough room for the mechanics I've decided that I'll put in 5 micro motors in a 1:8 ratio (worm + 8 tooth); 1 in each wing, 1 in the rudder and 1 in each tail flaps. The motors are small and will "easily" fit anywhere close to the moving flaps/rudder.

However, the micro motors cost literally and arm and a leg on bricklink so if anyone has got some lying around they don't want anymore (LOL), I'll gladly take hold of them for a smaller price.

c) The structure it self is plenty rigid both up- and sideways. However, the tail is really flexy in a rotational matter. This isn't so good and I don't know what I can do to stabilize that. I hope that once it gets coated with something, it won't flex as much.

d) ??????

e) 29 kg sounds like a whole lot, heck even 14 kg, I don't think it'll be that heavy but we'll see. I think I'll need to have some special crafted propellers just for me that has got the right size and shape. It'll probably be quite expensive too :sceptic:

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Isn't the weight cubed not squared when scaled?

I have no idea but if so, the weight shall not exceed 10,7 kgs - cuberoot((19.150/15,65))

I think it's possible, but lets see

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c) The structure it self is plenty rigid both up- and sideways. However, the tail is really flexy in a rotational matter. This isn't so good and I don't know what I can do to stabilize that. I hope that once it gets coated with something, it won't flex as much.

Elevators (the horizontal tail mobile parts) push up and down, and rudder (the vertical flap) push sideways. They actually create surprisingly little force (the plane is in the air after all, and it only needs to rotate the pertinent axis) So you should be ok with what you have.

d) ??????

d) Center of Gravity is Very important. As the tail produces only small forces, a deviated CG means an uncontrollable airplane. For ideal results, the center of gravity should be about 2% to 5% ahead of the center of lift. That way the plane has a slight tendence to nose-down, wich makes stall recovery, enter gliding, etc. easier for the pilot.

Isn't the weight cubed not squared when scaled?

I totally failed there :D Yes, the weight is cubed. After all, we're scaling on 3 dimensions :D The new math is correct.

Edited by Big Cam

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Elevators (the horizontal tail mobile parts) push up and down, and rudder (the vertical flap) push sideways. They actually create surprisingly little force (the plane is in the air after all, and it only needs to rotate the pertinent axis) So you should be ok with what you have.

That's good to know

d) Center of Gravity is Very important. As the tail produces only small forces, a deviated CG means an uncontrollable airplane. For ideal results, the center of gravity should be about 2% to 5% ahead of the center of lift. That way the plane has a slight tendence to nose-down, wich makes stall recovery, enter gliding, etc. easier for the pilot.

Ah, center of gravity, yeah that's quite important, I just didn't udnerstand what you meant by CG. This should easily be solved by placing battery packs correctly.

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Today I've rebuild the wings in order to reduce the amount of play in the flaps. I had to retract the carbon rod a bit in order to fit it.

I hope that the amount that's too tall compared to the rest of the wing doesn't have influence on it's flying abilities. Should I place the micro motor beneath the wing instead?

EDIT: Forgot to mention that this first picture is just to show that carbon rod under the wing. Besides that, there are 5 additional mounting points on the wing. I'm about to reinforce the body where the wings are so that the plane won't get completely oval when airborne (and to reduce a spring-like effect in the body).

I have also removed the chains driving the tail and hope to get some great idea on how to make that the best it can be.

ynlHneL.jpg

X1mkayC.jpg

cSDb9ej.jpg

aNq1pQu.jpg

Notice in this last picture that it sticks half a stud above the wing. Would it be better to have that kind of obstacle on the underside of the wing?

Forgot to mention that I weighed the plane with a luggage hand-weight and it old me that it was only 4,15 kg. AWESOME :grin:

Edited by Carsten Svendsen

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Notice that I plan on using only the studded micro motor plates in this case

Note: Picture no.2 is the newest picture (reinforced the micro motor's position

Edited by Carsten Svendsen

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I must say, this project is really fantastic and it's one of the best Lego planes I have ever seen. It's also rather big and I like big MOCs, especially, when they are beautiful and functional)

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As long as you add a fairing in front and rear of the micro motor, it shouldn't affect flying caracteristics. Otherwise, it would be like a spoiler. Better explain this with a drawing.

25p4z2x.png

On wing A you can see how a normal wing works.

Wing B has a deformation that causes airflow to be disrupted and produce vortexes. A disrupted airflow creates very little differential pressure, diminishing lift by a great amount, and the energy to power the vortexs comes from the motion of the airplane, therefore increasing drag. In fact, the efect is so strong, that some airplanes are equipped with "spoilers" that deform the wing to slow down and descend faster (For example gliders)

FSX-DG-glider.jpg

And on Wing C the fairings avoid most of the "spoiler" effect, but still there is a deformation of wing shape, wich causes lift to be roughly equal to drag.

Cheers :D

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My two cents - micro-motors are very slow. Being geared down to 1:8 it will be very-very slow. Typical servo used in RC models are 2-3 times faster (80-90 RPM vs 35 RPM) and have ten times more torque. I believe torque, developed by micro-motor could be considered enough for mild and slow flight, but response time when using geared down micro-motor will be very big so it will be very hard to control aircraft.

Also RC servos have feedback circuit with potentiometer on output shaft (and microprocessor, one task of which is to keep requested angle on control surface), which, in turn, leads to question - how are you going to control the aircraft if it is supposed to lift off the ground?

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whale2, the micromotor is the smallest available lego motor, and I'm sure the speed is ok for what it needs to be used for....

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Sure it is smallest. I just trying to say that gearing it down will make very large lag between control input and aircraft response. It will take more than 3 seconds to move aileron from 45 degrees up to 45 degrees down. So if plane is banking right and you move a stick to left, the plane will respond in 3 seconds or more. This makes the plane very hard, if ever possible, to control.

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