Antonov AN-140

[Carsten Svendsen]

OK, so your approximate wing area based on average chord is S = [(11+19)/2]*155 = 2325 cm^2. We need this in square meters so that's S = 0.2325 m^2.

For calculation purposes, I'm going to assume that you have an airfoil equivalent to NACA 2415. In order to by able to fly with a reasonable amount of drag, we'll assume that you need to be able to take off with an angle of attack of alpha = 10 degrees (which is very generous). Based on the lift coefficient charts, your lift coefficient is CL = 1.0. This is really good and your actual airfoil will probably be less efficient than this.

For the density of air, we'll assume standard sea level conditions. rho = 0.0023769 slug/ft^3 or 1.2012 kg/m^3.

Lift is equal to weight which is 5 kg (this is actually a mass).

Now we can get the velocity V for takeoff (no climb) using V = SQRT [2L/(CL*rho*S)] = 5.98 m/s or 21.5 km/hr

This is not a scale speed, this is actual speed. To actually be able to climb and maneuver you'll need a lot more speed than this and you really don't want to be flying at an alpha of 10 degrees, so you'll want your top speed to be about 3 times this or 60 kph. The drag forces on your plane at 60 kph are going to be very high, so you will need very high power to achieve this speed. I would plan for at least 2.5 kg of thrust.

Structurally, you'll need to make sure that your plane can be lifted by the wings with a factor for gusts. I would lift it up by the wings at about 1/2 span and shake it up and down and make sure they stay on. If they don't they will break off in the air.

Plan your center of gravity to be at about the 1/4 chord point of the wing.

Thank you Blackbird, for the calculations and min. motor size. This will come in handy

will need videos of the wing tests :)

Videos of the wing test will be available once they're taken

Now this is truley a masterpiece

155 cm? Thats just 22 cm smaller than me!

about how many pieces is it?

How many pieces? I dunno, but for that I will have to build it in SR3D Builder first to figure that out. It'd also be awesome with a computer model of it. That way, I can rebuild it if it ever becomes a scrapyard for other models

[Carsten Svendsen]

I have now incorporated the servo motor into the rudder. It turned out that the 32L axle used was a tiny bit twisted and therefore the rudder will return to the exact center when idle. Cool eh?

The really tricky part will be to attach the horizontal stabilizer with rudder movement. The elevators will be 6L in total width so I hope there'll be some space to make it fit.

Here's a video of the rudder in action:

Are you still sure about the flexibility of the tail?

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.

Edited June 6, 2015 by Carsten Svendsen

[TotalyWicked]

Do you have an idea what mottors, props, li-po are you going to use to power this beast??

[Carsten Svendsen]

I was thinking of some custom made propellers made in metal. I have no idea where I should order those though - An suggestions?

For motors I was thinking of either EMP or Leopard as they look good. I konw nothing about this stuff though.

If no one here knows anything, I'm gonna make an account on an airplane forum. and ask there for getting the optimal performance

[whale2]

I don't get why you would ever need metal propeller.

For rough estimation on propellers and motors combination you could use this nice tool:

http://flbeagle.rchomepage.com/software/webocalc_1.7.6/webocalc.html

How are you going to integrate Lego servomotor with RC servo or RC receiver? AFAIK, PWM frequency used by Lego servo motor is significantly higher than that used in RC servos.

[Carsten Svendsen]

I thought that a metal propeller would be the best since it's quite sturdy and rigid - bear in mind, I have never had or built an RC plane before.

Found this website while searching for Kv on the engines. It's got some information on the propeller used on the Antonov AN-140, and I don't understand a single thing of it

http://en.aerosila.r...n_content&id=35

I wish I had found this information much earlier in the starting phase since there's an exact measurement on the propellers. 3,75 / 15,65 = 23,77 cm which is pretty close to my measured 22 cm on the blueprints. What luck!

I wonder if someone is able to get the necessary blueprints of the propellers for an exact duplication.

Regarding the servos, I thought of two possibilities:

1 - Have an RC servo control a separate PF rechargeable batty pack with the cost of adjustments like in the video.

2 - Install a 9.6V battery on to the RC reciever then put a resistive load on the RC servo cables. Then mod some PF cables to fit in the RC receiver. That would make linear voltage increments for the LEGO servos.

Or perhaps this image could help a bit in reconstructing the propellers. I don't know what the angle of attack should be though, probably somewhere in between feather and unfeathered. Is it even possible to make model propellers work mechanically like that? I guess I could add a tiny servo motor to the throttle channel to adjust the pitch of the propeller?

Edited January 20, 2013 by Carsten Svendsen

[whale2]

You will hardly find 6-blade propeller in RC world. Also, you can't just scale down original propeller and have it do required job in desired way. When scaling aerodynamic kind of thing many factors do apply. For instance you could take a look to this page how scale factor applies to different physical values - http://www.mnbigbirds.com/Scale%20Factors%20Page.htm

May be you could combine two three-bladed propeller and make it 6-bladed, but I would rather started with propeller that will do right job and then go forward to similarity with original aircraft. Also remember, that adding blades increases a load of propeller of same diameter, perhaps you will have to experiment with different props.

Variable pitch propeller, however, do exists, but they should be combined either with specialized motor with hollow shaft or with gearbox.

Examples:

http://www.hobbyking.com/hobbyking/store/__6220__Variable_pitch_prop_motor_set_10_Type_A.html

http://www.horizonhobby.com/products/EFLPVPP100

And variable pitch should probably take it's own control channel, unless you are able to generate PWM for ESC for constant speed.

Variable pitch propeller is harder to implement, but it have the same advantage over constant pitch prop as having a car with single gear or complete gearbox (or even variator)

[TotalyWicked]

Well,

Am I reading this right???? You have 0 RC flying experiences?

As for power:

I am guessing your airfoil is going to produce minimum life, so you will need a “proper” power system.

What do you think the final weight going to be???

I think you would want to have close power to weight ratio of 1:1.

[Blakbird]

Am I reading this right???? You have 0 RC flying experiences?

You have no chance of flying this without R/C flying experience, even if it is airworthy. I have a degree in Aerospace Engineering and have piloted real aircraft, and I still crashed my first R/C plane within 5 seconds of takeoff. It takes a lot of practice to be competent at it. You need to practice and become competent at flying aircraft you know are properly powered and stable before you can hope to become a "test pilot" which requires superlative skills. This will also teach you a lot about motors, props, and batteries which is knowledge you will require. I have enough experience to tell you that you'll be using brushless outrunner motors with 2 blade composite props direct driven and probably 3 cell lithium-polymer batteries with about a 5000 mAh capacity. The power and radio setup will cost you about a thousand dollars if you don't already have the transmitter.

[ap0r]

Ooops, i tought you had experience with RC planes already! Agree with Blackbird and Whale You CANNOT use this model as a trainer! I am a pilot student in real life, i fly solo (as in by myself, with no help, alone in the plane) already, and i had lots of trouble handling a Trainer RC plane!

You should really get in touch with RC people in your area to find a test pilot. If you want to do it, you'll probably destroy this beautiful creation,

[TotalyWicked]

I have to agree with blackbird. I seen in plenty io time when a nice looking planes are crashed within seconds because, pilot has 0 experience.

Flying principles are basicly the same for RC and real plane. However in practice 2 different things....

My RC expirience:

Been flying RC for years. right now i am mostly into small planes 18-22 inch wing span, some kits some scratch build. So any RC questions I can help you no problems.

Back to power set up I would base it on a models final weight.....

2 x brushless outrunners, with 3-6 cell lipo's should do the trick....

With enough power you can make brick fly.....

P.S. Replying from my cell phone sorry for any mistakes...

Edited January 21, 2013 by TotalyWicked

[camaudio]

Get on the RC forums is a great idea. You might be able to find someone that can loan you the eqiupment as well as some pilot experience.

[Carsten Svendsen]

Guess I'll have to purchase a real model airplane and practice with that one first. It's just seems so easy; move the throttle stick up and use the ailerons for banking, elevator for up/down, and rudder for turn. How hard can it be?

Guess I'll find out......

How do I know if the motors are out- or inrunners? Hobby sites tend not to write it. I know what the difference is between them though.

I wonder about the batteries though. Motor charts state that they draw at least 50A and a 5Ah battery makes the airplane airborne for less than a minute?

Variable pitch control is out of the question then since it's way too advanced.

Composite things are made in a mold right? I don't know anyone who knows someone who knows someone, so I probably won't be able to get a 6 bladed propeller for cheaper than VERY expensive

However, it's worth an email to someone - recommendations? Or should I just go with a 3 bladed even though the model is wrong then?

At least there's something I'm good at

- And that's building LEGO. As soon as I'm done with this thing I'm gonna build something else that's easier to manage and that I have the pieces for. I haven't been building on anything else than this plane for 2 years now

That's why it's going slow atm. I'm getting tired about it and can't concentrate that much anymore (completely random connections and skewed angles), so I'll take it one step at the time atm.

That, and the winter season, I don't like building when it's dark outside (bad indoor lighting).

It'll be done soon though, no worries.

[Hopey]

I think the whole "It'll never fly" aspect of the conversation might have overshadowed the fact that this is an awesome MOC. It's still worth getting the best possible implementation of the various control surfaces, landing gear, etc, just for the sake of it. Folks build plenty of MOC cars with the best possible suspension, steering geometry, etc, without ever actually driving them in a way that utilises these, and often don't drive them at all. You just do it because you can.

I'm slightly concerned that if this thing fails to get off the ground, or even worse does a half takeoff then destroys itself, then you're going to be very disappointed. When, in fact you've built one of the best aeroplane MOCs I've ever seen, flying or not.

[TotalyWicked]

If you are serious about flying RC, let me give you few tips.

1. Download FMS. Its a free RC simulator. Put some hours into it to learn basics of flight, plane orientation etc....

2. For 1st plane I would recommended HZ Champ. Its RTF kit that includes everything, for about 100$ use. Its also one of the most forgiving and fun planes to fly.

3. After you get good with champ you can graduate to almost any plane...

[1974]

I don't get this project at all. If you're so keen on making the Antonov (or any other RC plane), LEGO is not the bits to use. It be like trying to build a car out of wood onlyl. Try joining some RC fora and listen to them

I'm sure you can make a really nice display model though

Also, you're gonna use non LEGO servos, control, motors and skin. All is left is a very heavy and poor frame that's gonna buckle once, if ever, it's in the air. And I also think you have to glue the lot just to get it airborne. Even if that works (and I think not), you can't really call this a LEGO airplane

Wrong (and expensive to boot) parts for the job, imho

Not going to wish you good luck as luck will not get it airborne. Science will. And science says no ..

Sorry to sound negative, but I think you're really barking up the wrong tree

Edit : too many speilling mistakes, sorry ..

Edited January 21, 2013 by 1974

[hrontos]

This LEGO plane this is an amazing project with a lot of details and great ideas. You have a great patience building it for two years.

But with flying this plane I would be more carefull to avoid disappointment. I would suggest to build some standard model plane first as a test. Kits are not that expensive and take only few days to build. I built some of them and it requires quite high level of precission to make it fly. Not get to air and crash after few moments, but to make it really fly. If I will not count that it has to be really sturdy construction it has to be also precise and well balanced. And this requires quite a lot of experience to calculate it for a custom model.

For a first flying model you can use any RTF model or a toy. Just to try it. Or a simulator. It is not that easy as it looks, mainly because it has to fly at certain speed and you have to react quite quickly. Movements have to be precise and quite "automatic". There are some styren foam based models that are good for beginners and can survive some crashes. And you can build them also. Try them as a bit of relax from this project since you mentioned your are tired and as a source of an inspiration.

[Blakbird]

How hard can it be?

That is the part that will surprise you. It is quite hard to learn, and much harder if your plane is not balanced or powered properly.

How do I know if the motors are out- or inrunners? Hobby sites tend not to write it. I know what the difference is between them though.

Outrunner just means that the coil is on the outside and rotates with the output shaft. This makes the output speed much slower with higher torque so you usually can direct drive a prop instead of gearing it down. Most modern motors are outrunners. You can tell by the diameter. Outrunners will have a very large diameter housing, probably the same dimension as the length of the motor. Regular motors are long and thin.

I wonder about the batteries though. Motor charts state that they draw at least 50A and a 5Ah battery makes the airplane airborne for less than a minute?

Yes, a plane this size could easily draw 50 Amps. Flying time of an R/C plane is often only a couple of minutes. Honestly, it takes so much concentration to fly that you can't go much longer than that anyway.

Composite things are made in a mold right? I don't know anyone who knows someone who knows someone, so I probably won't be able to get a 6 bladed propeller for cheaper than VERY expensive

However, it's worth an email to someone - recommendations? Or should I just go with a 3 bladed even though the model is wrong then?

You are going to want to get a prop that is matched to your motor output. So wait until you select a motor and the manufacturer will have prop recommendations for various battery voltages. Anything with more than 2 blades is very unusual, and you can't tell the difference once in flight anyway. You could make a 6 blade for display and use a 2 blade for flight.

[ap0r]

Quote

I wonder about the batteries though. Motor charts state that they draw at least 50A and a 5Ah battery makes the airplane airborne for less than a minute?

Yes, a plane this size could easily draw 50 Amps. Flying time of an R/C plane is often only a couple of minutes. Honestly, it takes so much concentration to fly that you can't go much longer than that anyway.

50 amp at full power (only for takeoff)

[TotalyWicked]

Quote

I wonder about the batteries though. Motor charts state that they draw at least 50A and a 5Ah battery makes the airplane airborne for less than a minute?

Yes, a plane this size could easily draw 50 Amps. Flying time of an R/C plane is often only a couple of minutes. Honestly, it takes so much concentration to fly that you can't go much longer than that anyway.

50 amp at full power (only for takeoff)

What i think they are reffering to on web site, is that you battery and ESC should be able to handle 50a for that specific motor.

Full power is not only for take off...

Ultimatly its all based in how you want to fly...

You can cruise and never exceed 3/4...

Or you can go "all out" and fly at full power entire time...

[whale2]

I wonder about the batteries though. Motor charts state that they draw at least 50A and a 5Ah battery makes the airplane airborne for less than a minute?

In theory 5 Ah battery can feed 50A for 6 minutes (5 A * h / 50 A = 1/10 h = 6 min)

[Carsten Svendsen]

1: I don't get this project at all. If you're so keen on making the Antonov (or any other RC plane), LEGO is not the bits to use. It be like trying to build a car out of wood only. Try joining some RC fora and listen to them

2: I'm sure you can make a really nice display model though

3: Also, you're gonna use non LEGO servos, control, motors and skin. All is left is a very heavy and poor frame that's gonna buckle once, if ever, it's in the air. And I also think you have to glue the lot just to get it airborne. Even if that works (and I think not), you can't really call this a LEGO airplane

4: Wrong (and expensive to boot) parts for the job, imho

5: Not going to wish you good luck as luck will not get it airborne. Science will. And science says no ..

Sorry to sound negative, but I think you're really barking up the wrong tree

1: I don't wanna make an RC plane, I wanna make a LEGO plane with the possibility for flying if using the right RC motors/batteries.

2: Yeah I'm gonna purchase another micro motor so I have two to put in the wings for showcase. I'll also install lego engines and lego propellers for the same circumstances.

3: The only non-lego will be, as already mentioned, engines, propellers and two servos for the wings, so saying that this isn't a LEGO airplane is a bit excessive don't you think?

I'm gonna try some different methods for coating that can easily be removed again without damaging the parts with sticky stuff.

The frame is not poor. It might look weal on the pictures (haven't checked) but it's a lot stronger than what you might think and it'll resist the forces, no problem.

No glue will ever be needed to make it stay together, ever!

4: Wrong parts for an RC plane? - yes. Expensive? - yes. But that's the cost of a hobby.

5: You're partly right. Luck alone won't get it airborne, but I have used a lot of luck on building this thing and I think I might need a refill for the initial testing.

So quit your bitching until I'm at least somewhat finished. Then you can say "I told you it wouldn't fly", but this ain't the right time.

I think the whole "It'll never fly" aspect of the conversation might have overshadowed the fact that this is an awesome MOC. It's still worth getting the best possible implementation of the various control surfaces, landing gear, etc, just for the sake of it. Folks build plenty of MOC cars with the best possible suspension, steering geometry, etc, without ever actually driving them in a way that utilises these, and often don't drive them at all. You just do it because you can.

I'm slightly concerned that if this thing fails to get off the ground, or even worse does a half takeoff then destroys itself, then you're going to be very disappointed. When, in fact you've built one of the best aeroplane MOCs I've ever seen, flying or not.

Yay, a nice comment for once

Thanks, it really is an "awesome" moc, but I can't make it more awesome than what I'm showing you guys without any input on what could be changed or redesigned.

This LEGO plane this is an amazing project with a lot of details and great ideas. You have a great patience building it for two years.

But with flying this plane I would be more carefull to avoid disappointment. I would suggest to build some standard model plane first as a test. Kits are not that expensive and take only few days to build. I built some of them and it requires quite high level of precission to make it fly. Not get to air and crash after few moments, but to make it really fly. If I will not count that it has to be really sturdy construction it has to be also precise and well balanced. And this requires quite a lot of experience to calculate it for a custom model.

Disappointment is just another factor of the building process. I don't expect it to fly the first time either, that would be damn lucky !

--------------------------

Regarding batteries, I could just purchase more than one for each motor and double the available current for the time needed in the air.

Thought of buying some positioning lights for the plane too at some point

[Carsten Svendsen]

I modified the horizontal stabilizer today for making elevators. It turns out that my previous measurement of 6 studs was all wrong. I had copied the scale file to my other computer which has got a bigger physical monitor so the measurements were incorrect. The correct measure is 4 studs, just like the ailerons.

Left: New

Right: Old

I also decided to swap out all the grey 1/4 pins with blue pins instead, as I think it looks much better that way.

Edited June 6, 2015 by Carsten Svendsen

[Carsten Svendsen]

Just wanted to say that I have made a better autovalve, than the one before (with clutch gear and XL motor). This one is with a sliding worm gear and a set of valves on each side of the construction.

It's been modified since the screenshot but you get the idea.

To prevent the small rotating beams from locking each other, I've put a soft spring plate on top of them to straighten them out when idle.

I'm not quite done yet though.

SR 3D File: Autovalve

The reason that it's better is that there are 4 valves instead of 3, it's less prone to to failure because there's no clutch gear that can get worn out inside. I have to get some of the new 8T gears though, because there's quite a lot of force at times. It also takes up less space than the previous solution, making more room for batteries and such.

Besides that, I'm having trouble with the rear horizontal wings. I could make them go straight of of the chassis, but they need to bend upwards as can be seen here

Once they're mounted, It'll be easy to make the elevators move by using the push-rod method and a servo motor in a 1:1.667 ratio.

Edited June 6, 2015 by Carsten Svendsen

[Carsten Svendsen]

Guess I scared everyone away from this thread two weeks ago

Anyway, the autovalve has been finished and installed. The fuselage has also been re-assembled (with major hassle) - I'm glad I made an .L3B file of the previous mechanism if this one fails.

I tested with a rechargeable battery and the large motor could barely make the valves and pumps rotate. It's been a while since it last had a charge so I think (hope) I'll get better results tomorrow. If not, I'll just swap it for an XL.

It should be easy enough to swap out the old 8T with the new 8T once I get hold of some.

Here's a short video of how it works now, and showing that it will never lock it self (yeah I tested for that before I put it in).

You have to excuse me for the background music, I forgot to turn it off and the editing program didn't have a "remove audio" option.