73 replies to this topic

[Saberwing40k]

So I bought 9396 as a birthday present to myself, and built it. It's a great set, but there were a couple of things that bugged me about it. Thankfully, I have a sizable collection of Technic parts, so I set to work.

The modifications include the addition of lights, a motor, an external switch, door locks, a better mount for the battery box, and some work on the winch boom.

But looking at it, you'd be hard pressed to see a difference between the stock model and my modded one.


a close-up of the nose, showing off the new headlights.


The door locks. simply lift up the red 2l liftarm, and slide back the door.


Door open. the clever part about the locks is that they also prevent the doors from slamming shut.


The external switch. This controls the lights and motor. I really could not think of a better place to put it, even if this location is not good for aerodynamics.


The motor. Just like the official instructions for motorization.


The underside. now the heli has a floor, but where does the battery go?


Pull out the four stop bush pins, and pull on the black panel.


Keep pulling, and the battery pack is revealed.


The battery pallet. Doesn't this look better then the stock install?


Another view.


A detailed look at how the headlights attach.


Lights out, headlights on.


The inside, showing the axle the door locks are mounted on. It's an 8l axle connected to a 5l axle, which is in turn held straight by 2 3l liftarms and an axle pin.


The end of the winch. the hook attaches with a stud, when not in use.


How the switch attaches.


And now for a little fun. Yes, the winch will lift good 'ol Splitface.


Well, so much for my happy landing. (For poor Splitface, anyway.)


Ah well, I couldn't include a witty caption with every picture, or a technical explanation, as it's just simple stuff. Comments and constructive criticism are always welcome. And don't worry, there will be more mods, and maybe a video, if you want. Thanks for reading!

[z3_2drive]

very nice simple mod, I don't own 9396, as I have 9398 and helicopter didnt interest me although its a good set. No criticism needed here, except make the switch placement a bit less obvious and try to take photos with a sharper focus, unless its just the camera...
the 7th and 17th photos were the sharpest.

Edited by z3_2drive, 04 August 2012 - 11:53 PM.

[sama]

I still don't know why TLG likes to place the m-motor on side ways .

[JunkstyleGio]

Here is another option for locking the slidingdoor on the chopper.



The friction pin goes only halfway in de liftarm, but its holds just fine.



And you all might have seen my PF-switch placement.

Edited by JunkstyleGio, 05 August 2012 - 11:32 PM.

[Crazydance]

JunkstyleGio, on 05 August 2012 - 09:01 PM, said:

Here is another option for locking the slidingdoor on the chopper.



The friction pin goes only halfway in de liftarm, but its holds just fine.



And you all might have seen may PF-switch placement.

Nice notifications! Makes the model much more playable than you should expect.

[VFracingteam]

Nice Mod's you make for it JunkstyleGio and good sharp pictures

[JunkstyleGio]

Here another little add-on for the helicopter.



It's a stand that fits nicely around the batteybox. This stand takes away the pressure on the landinggear when the model is on longtime display.



LDD  here
PDF here

Edited by JunkstyleGio, 07 August 2012 - 10:54 PM.

[Alasdair Ryan]

Some very cool changes.
How about putting a winch on it underneath so it could do some heavy lifting?

[davidmull]

Has anyone made it fly yet lol,after all 9398 does what's it says on the tin but that's probably why it's the flagship :)

[Saberwing40k]

davidmull, on 08 August 2012 - 12:34 AM, said:

Has anyone made it fly yet lol,after all 9398 does what's it says on the tin but that's probably why it's the flagship :)

I'm working on it, I'm working on it. No, seriously. Tomorrow I will be able to calculate how much power I'd need to get the bloody thing off the ground. I anticipate only 2 XL motors should do the job. I've actually picked up a remote control helicopter that flies, and it is frighteningly light. However, the motor is puny, which makes me confident in the power of the XL.

Anyway, due to JunkstyleGio hijacaking my thread, I'll just have to hijack it back. The trouble is, I don't have any ideas! So, what do you, the viewers, want me to do next? (aside from making it fly. )

[RohanBeckett]

Saberwing40k, on 08 August 2012 - 12:59 AM, said:

I'm working on it, I'm working on it. No, seriously. Tomorrow I will be able to calculate how much power I'd need to get the bloody thing off the ground. I anticipate only 2 XL motors should do the job. I've actually picked up a remote control helicopter that flies, and it is frighteningly light. However, the motor is puny, which makes me confident in the power of the XL.

While I admire your enthusiasm, and optimism... you will NOT get the 9396 to fly.
Lego is just far too heavy, and the motors are not strong enough

Nice big threads on it last year:
http://www.eurobrick...showtopic=56658

http://www.eurobrick...showtopic=60737



RB

Edited by RohanBeckett, 08 August 2012 - 01:44 AM.

[JunkstyleGio]

@ Saberwing40k:

I didn't try to steal your thread.
With posting my add-ons and MOD's I only tried to keep this thread a central place for all kinds of MOD's and /MOC's for this beautiful set.

BTW: Good luck on making it fly.

[daniele]

You dont need power but rpm. For making a flying choppa you will need a very powerfull lipo and a ultralight motor with a super fast rotating speed.
Don't forget lego axles will "burn" at high rotating speed :)

But hey, it's a dream world, have fun trying :)
(When I was a child, me and my friend built a plane with wood and paper. When completed, our parents burned before we tried it   )

EDIT: I have to change my mind after seen this. Withj a 1:15 gear ratio this plane, flies!!!

Edited by daniele, 08 August 2012 - 08:17 AM.

[vwpint]

Fake, it doesent fly.

[JunkstyleGio]

Let's please keep this thread for MOC's and MOd's.

RohanBeckett gave us a few threads where discussions on Lego flying (or not) are more appropriate.

[TimH]

Nice modifications Saberwing 40K and JunkstyleGio.  

[Saberwing40k]

Okay, so I'm trying to make 9396 fly. In order to calculate how much power I'm going to need, I have tried using a lift equation, but nothing useful comes out the other end. I've most certainly done something wrong, so could I get some help with this? Or, I could always go the brute force route, but that could be potentially be damaging to many things.

[VFracingteam]

Lego will never fly

[Blakbird]

Saberwing40k, on 09 August 2012 - 12:05 AM, said:

Okay, so I'm trying to make 9396 fly. In order to calculate how much power I'm going to need, I have tried using a lift equation, but nothing useful comes out the other end. I've most certainly done something wrong, so could I get some help with this? Or, I could always go the brute force route, but that could be potentially be damaging to many things.

In order to use a lift equation you would need to know the lift coefficient (CL) of the rotor airfoil. Obviously there is no test data to generate any such information because these rotors are not actually intended to produce lift. You could use a lift coefficient for a generic symmetric airfoil like an old NACA 2412 as a starting point and assume a certain angle of attack (alpha), maybe 10 degrees. Then you need the overall wetted area (S) which is the projected area of all the rotors put together. Then you need the dynamic pressure (q) which is a function of speed. This is harder for a helicopter than for an airplane because the speed changes as a function of diameter.

However, you can save yourself the trouble. Although there IS an angular velocity (omega) that you could mathematically calculate which would make the rotor lift the helicopter, the LEGO parts would structurally fail and/or melt LONG before you ever got such a velocity. And even if, by some miracle, you really could generate the required lift, 9396 has no gryo for directional stability, no pitch on the anti-torque rotor, and no cyclic to control heading and balance the suspended weight, so it would immediately fly into the nearest solid object, possibly your head, and smash.

It would be an interesting thought exercise to at least calculate the number and just see how ridiculous it is, but big computers with really complex calculus are used to calculate this kind of thing. Let's do it the easy way.

A Blade 300 heli has about the same rotor size as 9396, so let's use it for comparison. It uses a 4500kV brushless motor, a 3S Li-Po battery, and weighs about a pound. This means that the motor spins at about 50,000 rpm. The main spur drive has a 15.5:1 gear ratio so that means the rotor spins at ~3200 rpm at full power. Let's assume it only needs half power to take off and lift the 1 pound weight. 9396 has twice as many rotor blades (4) and the Blade 300 (2), but they are also not really designed for lift so let's assume those two things cancel out. That means we need 1600 rpm/pound of weight to lift off. 9396 weighs about 2 pounds (without PF) so let's assume it would be 3 pounds and therefore would need to rotate the blades at 1600 * 3 = 4800 rpm. The linear speed of each blade at the tip would be about 292 mph (469 kph). Assuming you were using a 3S lithium battery at 11.2 volts, you'd need a massive 6750kV brushless motor producing about 700W of power and drawing 60 Amps. Considering that the largest Lego motor, the XL, is only about 16kV and produces 7W of power at this voltage, you're going to need about 100 XL motors in parallel. The PF battery pack is also limited to 1 Amp, so you are going to need 60 battery packs. Of course, all of this gear weighs much more than the entire helicopter and you're also going to have to lift all that which means you need even more power, and the weight is going up faster than you can add motors and battery packs. Now suppose you just use real R/C components instead of PF to power it. Well, the power system is going to cost you about $1000 including motor, speed controller, and batteries. Now once you install them you'll be generating a 100x more torque than an XL motor. Since an XL motor can already destroy a plastic axle, you'll quickly vaporize your entire model.

Still want to try it?

Edited by Blakbird, 09 August 2012 - 01:58 AM.

[Kronos]

Blakbird, on 09 August 2012 - 01:57 AM, said:

In order to use a lift equation you would need to know the lift coefficient (CL) of the rotor airfoil. Obviously there is no test data to generate any such information because these rotors are not actually intended to produce lift. You could use a lift coefficient for a generic symmetric airfoil like an old NACA 2412 as a starting point and assume a certain angle of attack (alpha), maybe 10 degrees. Then you need the overall wetted area (S) which is the projected area of all the rotors put together. Then you need the dynamic pressure (q) which is a function of speed. This is harder for a helicopter than for an airplane because the speed changes as a function of diameter.

However, you can save yourself the trouble. Although there IS an angular velocity (omega) that you could mathematically calculate which would make the rotor lift the helicopter, the LEGO parts would structurally fail and/or melt LONG before you ever got such a velocity. And even if, by some miracle, you really could generate the required lift, 9396 has no gryo for directional stability, no pitch on the anti-torque rotor, and no cyclic to control heading and balance the suspended weight, so it would immediately fly into the nearest solid object, possibly your head, and smash.

It would be an interesting thought exercise to at least calculate the number and just see how ridiculous it is, but big computers with really complex calculus are used to calculate this kind of thing. Let's do it the easy way.

A Blade 300 heli has about the same rotor size as 9396, so let's use it for comparison. It uses a 4500kV brushless motor, a 3S Li-Po battery, and weighs about a pound. This means that the motor spins at about 50,000 rpm. The main spur drive has a 15.5:1 gear ratio so that means the rotor spins at ~3200 rpm at full power. Let's assume it only needs half power to take off and lift the 1 pound weight. 9396 has twice as many rotor blades (4) and the Blade 300 (2), but they are also not really designed for lift so let's assume those two things cancel out. That means we need 1600 rpm/pound of weight to lift off. 9396 weighs about 2 pounds (without PF) so let's assume it would be 3 pounds and therefore would need to rotate the blades at 1600 * 3 = 4800 rpm. The linear speed of each blade at the tip would be about 292 mph (469 kph). Assuming you were using a 3S lithium battery at 11.2 volts, you'd need a massive 6750kV brushless motor producing about 700W of power and drawing 60 Amps. Considering that the largest Lego motor, the XL, is only about 16kV and produces 7W of power at this voltage, you're going to need about 100 XL motors in parallel. The PF battery pack is also limited to 1 Amp, so you are going to need 60 battery packs. Of course, all of this gear weighs much more than the entire helicopter and you're also going to have to lift all that which means you need even more power, and the weight is going up faster than you can add motors and battery packs. Now suppose you just use real R/C components instead of PF to power it. Well, the power system is going to cost you about $1000 including motor, speed controller, and batteries. Now once you install them you'll be generating a 100x more torque than an XL motor. Since an XL motor can already destroy a plastic axle, you'll quickly vaporize your entire model.

Still want to try it?

OK, now my head hurts.....

[Saberwing40k]

Blakbird, on 09 August 2012 - 01:57 AM, said:

Still want to try it?

OH HECK YES!!!!!! You supposedly can't make a lead balloon, you allegedly can't make a concrete glider, and you most certainly cannot make a Lego helicopter. Except the first two have been proven possible. You say that I'll need 1600 rpm per pound, so what if I can make the heli weigh only 1.5 or so pounds? I've actually got Xl motors to go that speed with a geartrain. And, I don't have to worry about the 1 amp battery box limit, as I will be using a train speed regulator, which has the bonus feature of outputting 12, not 9, volts. It doesn't have to fly free, but it has to get off the ground. And then fame and fortune will be mine. MWAHAHAHAHAHAHAHAHA!!!!!!!!!!!!!!!!!!



At the very least, it will be funny to watch me screw up.

Edited by Saberwing40k, 09 August 2012 - 02:58 AM.

[Blakbird]

Saberwing40k, on 09 August 2012 - 02:57 AM, said:

OH HECK YES!!!!!! You supposedly can't make a lead balloon, you allegedly can't make a concrete glider, and you most certainly cannot make a Lego helicopter. Except the first two have been proven possible. You say that I'll need 1600 rpm per pound, so what if I can make the heli weigh only 1.5 or so pounds? I've actually got Xl motors to go that speed with a geartrain. And, I don't have to worry about the 1 amp battery box limit, as I will be using a train speed regulator, which has the bonus feature of outputting 12, not 9, volts. It doesn't have to fly free, but it has to get off the ground. And then fame and fortune will be mine. MWAHAHAHAHAHAHAHAHA!!!!!!!!!!!!!!!!!!

At the very least, it will be funny to watch me screw up.

You read all that and just got "1600 rpm/pound" out of it? Selective reading!

Well, if you make it weigh 1.5 pounds then it won't be a 9396 model and you have not achieved your objective. Yes, you can make an XL turn that fast but then it has almost no torque. The train speed regulator also only puts out about an amp or 2, but not having to lift the battery will help! If you used an automotive jump starter you might be able to briefly get the 60+ amps you will need. Or a car battery. And jumper cables.

I see that you cannot be dissuaded by logic. Oh well. If you manage to do it, you'll win the Collier Trophy and in fact, fame and fortune WILL be yours. If we all watch you screw up, you'll get a different kind of fame.... Fun either way! I can't wait to see the results! I will personally congratulate your brilliance and success if you can put the heli on a scale and manage to generate more than 2 ounces of lift. Good luck to you!

Edited by Blakbird, 09 August 2012 - 04:57 AM.

[dhc6twinotter]

Nice mods!

Do the blades on the 9396 have any kind of airfoil shape?  They look pretty flat too me.

[JunkstyleGio]

Easiest way to make Lego fly: Let call some people at ILM and let them do some CGI-version of it.....

[Alasdair Ryan]

Why don't you just chuck it out of the window then it will fly........
I can't wait to see a video of you trying though.

Edited by Alasdair Ryan, 09 August 2012 - 10:12 AM.