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My 3rd MOCiversary: The first ever working 5-blade helicopter rotor from Lego
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MD500 with 5-blade rotor, 4 channel dual controls, electric drive, shooting TOW missiles, shooting belt-feed cannon, 3 Technic figures in scale 1:20
About this creation
*Visit my Lego helicopters blog also

**See model and building instructions in Lego Digital Designer (LDD) for MD500D Marines: Here


Figure 1: IAF MD500 Defender intercepts assault executive transport above Gaza Strip, back view
See scene in LDD: Here


Figure 2: IAF MD500 Defender intercepts assault executive transport above Gaza Strip, front view

1 Introduction and inspiration

I celebrate my 3rd MOCiversary with designing and publishing building guide of a helicopter which summarizes all my building tricks and techniques developed so far. I selected one of the most compact military helicopters, MD500 Defender to build:


Figure 3: MD500 Defender of Israeli Air Force

-It’s fascinating egg-shaped cabin and 5-blade main rotor imposes serious modeling challenge if we want there working rotor controls and electric drive. TLG does not produce any type of hub-like part with pentagonal symmetry, and fairing/panel/windshield TLG parts are also very far from teardrop shape, so there are ample opportunities for creative problem solving.

-Small size of MD500 results in reasonable materials requirement, even building realistic helicopter in Technic figure scale (1:20), which can be afforded by most interested MOCers.

To create 5-blade working rotor, inspiration was given by Kurt MOC’s minifig MD500 from 2013. He solved 5-blade main rotor using TLG part ‘steering wheel 24mm’ as hub and created a very stylish, proportional and SNOT design. But this model does not contain any internal mechanics.


Figure 4: Kurt MOC’s minifig MD500, 2013

I have triple goals with my model:

-To develop further Kurt’s original 5-blade hub idea adding the maximal amount of functionality and realism, stretching the physical limits of Lego Technic.

-Improve curved, SNOT styling of the airframe and all aerodynamic surfaces.

-Try to keep proportional sizes of MD500 in scale 1:20 as much as possible.

I designed 3 versions (Air force, Marines, Civilian) of MD500. Let’s see them first in action:

2 Action screenshots of MD500


Figure 5: MD500 Aerial Welder Team arch welds Magma Chamber Observation Mast at Kilauea Volcano, Hawaii, Top view
See scene in LDD: Here


Figure 6: MD500 Aerial Welder Team arch welds Magma Chamber Observation Mast at Kilauea Volcano, Hawaii, Front view


Figure 7: MD500 Aerial Welder Team arch welds Magma Chamber Observation Mast at Kilauea Volcano, Hawaii, Bottom view


Figure 8: MD500 Aerial Welder Team arch welds Magma Chamber Observation Mast at Kilauea Volcano, Hawaii, Overview


Figure 9: MD500 Defender in power dive
See scene in LDD: Here


Figure 10: MD500 Defender maintenance and reloading in a desert location
See scene in LDD: Here


Figure 11: MD500 Defender, Top View
See scene in LDD: Here


Figure 12: MD500 Defender, Front View


Figure 13: MD500 Defender, Back View


Figure 14: MD500 Defender, Left View


Figure 15: MD500 Defender, Right View


Figure 16: MD500 Defender, Bottom View


Figure 17: MD500 Defender, Left Top Panel View


Figure 18: MD500 Defender, Right Top Panel View


Figure 19: MD500 Defender, Crew

All 4 seats are compatible with the size of Technic figures (12 studs tall, 4 stud wide shoulders, 2×1 stud wide body). As production of Technic figures are stopped by TLG, and LDD does not contain any Technic figures, I recreated them from Technic parts. They look too tall and too thin like basketball player type of guys. This is because in scale 1:20, 12 studs equals 1.92 m (6 ft 3.54 in). One stud shorter would be more close to average Caucasian body (two studs shorter for average Asian), but I did not want to take advantage on building my own figures and preserved the original sizes, to be compatible. Although making the long legs fit into the small cabin was hell, especially at the narrow tailed rear seats. I used the dirty tricks of automotive industry at subcompact cars: leg of the rear guy goes in the cavity left under the forward seat, and back of forward seat is unified with the middle frame of the cabin. Any Lego SWAT member jumping in and out rear seat all the day with shotgun in hand will curse me for that… Rear 2 seats are easy to remove for cargo.


Figure 20: MD500D Marines, Top View
See scene in LDD: Here


Figure 21: MD500D Marines, Front View


Figure 22: MD500D Marines, Back View


Figure 23: MD500D Marines, Left View


Figure 24: MD500D Marines, Right View


Figure 25: MD500D Marines, Bottom View

3 Technical details of MD500

*This part is technical and for helicopter builders with at least some experience. If you do not understand how do helicopter controls work, you can find an excellent summary at: www.aviastar.org

**In the forthcoming technical description, functional parts of MD500 are referenced by numbers which can be found on technical drawings attached

***Parts of MD500 are color-coded by their function:
- Yellow: Manual handles of working functions
- Gray/Black: static and dynamic parts
- Dark green/Orange: Pilots
- Blue: Seat of pilot
- Khaki: Weapons
- Light green: Tail surfaces


Figure 26: Overview of mechanics
See model in LDD: Here

3.1 Main rotor



Figure 27: Main rotor, Cutaway View

Building a small but realistic rotor was largely made possible by TLG introducing ‘Blade 16M with cross axle’ in Bionicle. Originally it is intended as an oversized sword for some exotic Bionicle fighters, but apart from some decorative details, it is quite similar to rotor blades light helicopters. Anyway TLG does not support us very well with aerodynamic SNOT rotor blades: putting a studded bar in the airflow is funny, but only until you play with Duplo. The first specialized helicopter rotor blade part was introduced in 2010, but - totally pointlessly - it has studs on the top, making all aircraft engineers really cry. Finally, in 2012 at 9396, a SNOT rotor blade was introduced, but its blade root is so awkward, that I prefer to build SNOT blades from curved fairing elements and Technic cross axles. But that solution is too bulky for a small rotor.
Another modeling challenge was to create pentagonal rotor hub, as TLG does not produce any hub-like part with pentagonal symmetry (except ‘starfish’…). Therefore the hub is created from 2 ‘steering wheel 24mm’ parts (R7, R8) stacked on each other at the top of rotor mast (R12). They have circular rim, which can be grabbed by ‘stick with holders’ placed there radially, and used as yawing hinges of rotor blades (R13). This way, rotor blades can be fixed on the rims of steering wheels at any angle. The biggest disadvantage of this solution is that it can tolerate only limited amount of centrifugal force, therefore it is suitable only for small rotors. The situation would be better if holders were placed on rim not radially, but vertically, but in this case they will collide with Y-shaped spokes of steering wheel in pentagonal layout. However 3, 4, 6, 8-blade rotors are perfectly feasible in this centrifugal force-tolerant way, only 5-blade is troublesome.
Interested readers may notice that not all rotor blades are set to correct 72 degrees spacing of a 5-blade rotor. This is not the error of the design, but of LDD: it renders rim of steering wheel as a 24-sided polygon, therefore at least one blade cannot be set in correct angle relative to others, regardless how steering wheels are rotated, because blade will “yaw” on the corner of the polygon. This will not happen building from real Lego.
However, it is not a big problem anyway, as blades of real helicopter rotors also “yaw” and “flap” by hinges or elastic joints, to dump the strong vibrations created by their downstream colliding with helicopters airframe or ground obstacles. Therefore, I fixed rubber yaw dampers (R6) on blade roots (R5) made from ‘rubber damper 2×1×1’. This way, 5 blade roots are mutually push each other aside with equal force, forming an elastic ring around rotor hub. If one blade is yawed, it will regain its correct angle soon because of rubber yaw dampers. (Note: As LDD cannot draw rubber elements compressed/distorted, therefore some of the ‘rubber damper 2×1×1’ parts are simulated with same sized black ‘technic beam 2×1×1’ at the LDD model.)

3.2 Drivetrain


Figure 28: Drivetrain
See model in LDD: Here

Designing the drivetrain, I tried to avoid common mistake of many TLG and MOC helicopters, where main- and tail rotor are geared 1:1, while in the reality it is 1:10. Such a reduction gearing would eat up lot of space, but at least I managed put there 1:3 reduction ratio by Z8/Z24 gears combo (E2).
The biggest modeling challenge here was that PF M-sized electric motor (E3) is rather bulky compared to MD500 cabin in scale 1:20. The real MD500 has 1 Allison 250-C30 Turboshaft engine rated 650 hp (485 kW) and mounted in 45 degrees angle downward back to main rotor mast. This engine is so small that it leaves pretty much void space behind half-conical shaped engine cover plates. Against that, we could hardly squeeze the 0.00027 kW rated PF M-motor mounted horizontally beneath ‘cone half 8×4×6’ part as removable engine cover. The space left between rear end of motor and the cover is 0.00mm. So, dear TLG guys, you have plenty of opportunity to develop smaller and more effective motors…
The situation is even direr with batteries. The bulky PF battery pack would not fit inside even if I sacrificed the rear 2 seats. So I decided to build removable water floats (creating MD500D Marines version), where 2 AA-batteries can be dipped inside the cavities of the 2 floats. Of course, it requires home-made electric wiring.

3.3 Collective blade pitch control


Figure 29: Collective blade pitch control
See model in LDD: Here

Although TLG produces specialized swashplate part (a large diameter bearing with 2 sets of ball joints and cardan-hinge in its center), it is rather bulky and it has erroneous design, as it cannot slide up/down freely on main rotor axis. Therefore the key of creating any compact working helicopter rotors from Technic is to avoid the need of conventional swashplate. This is done in the following way:

-All 5 rotor blades have individual rubber torsion springs (R4) made of TLG part ‘rubber dumper 2×1×1’ forcing gently their half axises to zero degree pitch.

-Therefore changing blade pitch requires simple pushrods (R11) connected to blade pitch control arms (R3) instead of using ball joint-connected linkage.

-Blade pitch control pushrods can slide up/down aligned by leading slots (R10) fixed to blade roots (R5), so they are NOT aligned by swashplate.

-Therefore, (C1) swashplate can be just plain plate with a hole in the middle letting through main rotor mast, and being tiltable/ liftable around that. Lower ends of blade pitch pushrods (R11) slide on the plate’s surface.

-Swashplate is aligned by pin+fork assembly (C2), which allows it lift/tilt but prevents it rotating.

Collective pitch control is done lifting/lowering swashplate with the help of sleeves (C32) sliding on main rotor mast (R12), when pilots pull collective control lever (C31) up/down.

3.4 Cyclic blade pitch control


Figure 30: Cyclic blade pitch control
See model in LDD: Here

Cyclic blade pitch control requires tilting swashplate forward/back and left/right. Building very compact collective-cyclic mixing linkage - which decouples cyclic and collective control – was a great modeling challenge, as it requires lot of swingarms, hinges and trackrods, which eat up space dramatically in such a small scale. It works by the following way:

-(C1) Swashplate is tilted by up/down motion of vertical track rods (C4) connected with ball joints (C3)

-Vertical movement of vertical track rods is converted into horizontal movement of horizontal track rods (C11) with the help of two 90 degree swing arm units (C34), whose pivot axises move up/down together with collective control.

-Another set of 90 degree swingarms (C13) connect horizontal trackrods (C11) with double yokes (C14). Double yokes are synchronized with trackrod (C15)

Horizontal cyclic track rods (C11) run under the cabin floor. This destroys aesthetics if helicopter is viewed from the bottom, but saves lot of space. With this trick, we could place 4 seats of the original 5 besides the bulky collective-cyclic mixer linkage. However, we sacrificed cabin doors, and ammo belt of Autocannon will eat up space of the 4th crew member (although real MD500 Defender rarely flies with crew of 4 when loaded with ammo).

3.5 Yaw control



Figure 31: Tail rotor

Creating variable pitch tail rotor in such a small size, there are 2 difficulties:

-We need a small driving ring (C27), which can slide on tail rotor axis easily, and pitch control rods (C28) can be connected to that. This is solved with the combination of TLG parts ‘Hub 17mm with Technic snap’, ‘Tap 4.9/6.4mm’, ‘Skeleton arm No.3’.

-We need short streamlined rotor blades. This is the only point where I sacrificed functionality for historical correctness. I could create streamlined tail rotor blades from TLG part ‘Wing, minifig buzz’, but they are too wide, destroying aesthetics. So I used here ‘Plate 1×4 with 2 studs’, which has the correct size but it is not streamlined.


Figure 32: Yaw control
See model in LDD: Here

Yaw control linkage is simpler than cyclic-collective mixer linkage, but it has to stretch from the nose to the tail of a helicopter, so it is also eats up lot of space. I used 2 building tricks here:

-Pseudo tail boom trick: MD500 has very thin, torque tube type tail boom. As we have no any torque tube in Technic, we need at least 3 rods for the tail: 1. Tail boom spar 2. Tail rotor transmission shaft 3.Yaw control rod. While a proportionally sized tail would allow 2×1-1×1 studs cross-section. I covered transmission shaft and yaw control rod with ‘Technic beam 2×1×1’ parts for a realistic looking tail boom, but they can rotate/ slide freely inside. The real tail boom providing structural support is a separate rod from ‘technic cross axles’ in black color, to dim its presence aesthetically.

-Half axises of left/right set (C16, C17) of dual yaw control pedals are also used as pivots of yoke swingarms to save space.

3.6 32mm Autocannon


Figure 33: Firing cycle of 32mm Autocannon, Phase 1
See model in LDD: Here

Pursuing maximal functionality means that we need shooting armament in MD500. I developed shooting 32mm Autocannon based on my earlier Handbook of Building Working Guns for Bionicle Figures MOC. A 32mm (1.26”) gun is a little bit oversized weapon for MD500 in the reality, as its recoil would tear apart such a light craft, but this is the most compact shooting mechanism with belt-feed autoloader I could create:

-Propellant force for shooting is provided by 2 steel springs from disassembled ‘Shock absorber extra hard’ TLG parts (G13).

-Rotating bolt (G5) is made from TLG part ‘Mini rapier’ and accelerates projectiles in 3 studs (24mm) long track.

-Barrel (G1) is made from ‘Outer cable 8 studs’, which have 1.6mm inner bore.

-1.5×18mm projectiles are the only non-TLG parts, as TLG does not produce reasonably small parts because of children safety, moreover ABS material is too easy for projectiles. So they are made from 1.5mm copper or aluminum wire can be found as electric wiring in any hardware store.

-Projectiles (G16) are feed from disintegrating ammo belt (G14) made from TLG parts ‘technic beam 2×1×1’ and ‘connector peg with knob’. As the latter has 3.2mm inner bore, which is too large, there is a choke in front of each belt cavity made from ‘bracelet upper part’, reducing its bore to 1.6mm. Projectiles are fixed in belt with the help tiny pieces of used chewing gum. When it is aged and dries out, it becomes fragile, so bolt (G5) can break off projectiles from belt easily, and they do not leave sticky residues inside barrel. Belt is falling apart by the shock of shooting and spent belt links (G13) are ejected by advancement of belt.

Firing cycle of 32mm Autocannon is the following:

-PHASE 1: Cocked bolt (G5) is released by rotating charging handle/trigger (G12) 90 degrees right upward


Figure 34: Firing cycle of 32mm Autocannon, Phase 2
See model in LDD: Here

-PHASE2: Springs (G13) press bolt (G5) forward. Tip of the bolt locks the belt (G4) in its actual position, and projectile (G16) is pressed from the belt into barrel (G1) and launched.

-In the meantime, bolt (G5) hits knob (G8) of loading arm (G9), and forces rotate it outward 11 degrees, against the force of torsion spring (G11) made from ‘Cross axle 2 studs’.

-Therefore, magazine catch (G6) placed at the end of loading arm clicks into new position of the belt.


Figure 35: Firing cycle of 32mm Autocannon, Phase 3
See model in LDD: Here

-PHASE3: When bolt (G5) is pulled back again at re-cocking, it relieves pressure on loading arm knob (G8), then retreating tip of bolt unlocks belt (G4). So, the loading arm (G9) – forced by torsion spring (G11) – rotates 11 degrees inward and advances belt (G4) one position further through belt catch (G6), and the new projectile moves in line with cocked bolt.

3.7 BGM-71 TOW missiles

TOW stands for Tube-Launched, Optical-Targeted, Wire-Guided Anti-Armor Missile developed by Hughes Aircraft in 1971 and continuously improved since that. Its advantages are relative cheapness and accessibility. As the missile is controlled during its flight by electric signals traveling on a double piano wire spooling down from a coil, it is relatively safe against Electronic Counter Measures (ECM). Disadvantages are limited range by wire (max. 3750m), limited speed to prevent tearing the wire (187m/sec in average) , limited armor piercing (630 mm) by 3.1 kg HE warhead, and the biggest one: launching platform has to keep target in line of sight during whole flight time of missile (max. 20secs) being an easy target itself for AA guns. Its semi-automatic optical guidance requires a gyro-stabilized periscope sight with an ocular. At helicopters it is usually placed at cockpit roof, this way at least the cabin of the helicopter can be behind some cover during targeting. At MD500 Defender it is placed ahead of left instrument panel, and its ocular protrudes backward from that, just before the weapons operator sitting at left forward seat:


Figure 36: BGM-71 TOW missiles, Loading
See model in LDD: Here

TOWs are originally launched from simple cylindrical shaped tubes, but when they were deployed at helicopters, a narrower nozzle tube was added at the back of launch tube to prevent hot propellant gases of the rocket motor to damage helicopter. Moreover, designers of real MD500 Defender covered the twin launch tube unit with streamlined fairing. In scale 1:20 TOW launch tube will require a thin walled tube with 1 stud (160mm) inner bore. We have nothing even close to that among TLG parts. So I built the streamlined twin casing (W1), and I will use that as launch tube. This solution has the disadvantage that you cannot aim exactly with the second missile, if the first is already fired.
My TOW missiles (W4, W5, W6, W7) are the smallest possible self-contained, self-propelled units can be built from TLG parts. They have flying spigot type launch mechanism (which was used in the reality at some special types of mortar shells - e.g. WWII Hedgedog ASW mortar):

-3 ‘shock absorber’ springs (W5) are held compressed by a long rod placed inside – called the spigot (W7) which flies out together with the warhead.

-Spigot is made from TLG part ‘Standard 3.2mm’, which has a 5mm diameter stop at its back. This stop could still slide through inside springs, but held back by a catch (W6) made from ’Stick with holder’.

-At loading, missile units are pushed gently into launch tube (W1), which has a 90 degrees flippable breech (W2), where trigger tubes (W3) made from ‘connector peg 3 studs’ can slide forward 1 stud. When missiles are loaded, breech is flipped down, and triggers are pressed forward gently to receive rear ends of spigots. This fixes breech and missiles in firing position.


Figure 37: BGM-71 TOW missiles, Loaded
See model in LDD: Here

-At firing, triggers (W3) are pressed forward hard. They try to push missiles in launch tube forward, but stick of the spring fixing catch (W6) will hit the rear end of the launch tube and break off.


Figure 38: BGM-71 TOW missiles, Launching
See model in LDD: Here

-This releases springs, which launch the warhead + spigot from the launch tube. The spigot rod stabilizes the warhead during flight. (This projectile much more resembles to a bazooka. The real TOW has 8 opening stabilizator- and steering wings, plus contact igniter extending forward, moreover releases a thin wire at its back for control, but I could not build these details in such a small scale.)

3.8 Instruments and avionics


Figure 39: Instrument panel

I wanted to build the cabin with transparent windshield, because while an excavator or bulldozer technic model looks pretty OK. without windscreen, a helicopter resembles to a burnt out scrap. But there is a lack of reasonably large curved TLG windshield parts for Technic figure-scaled models. I used the biggest possible glass dome part ‘Dome 8 studs with combi hinge’ as windscreen, and thicker outer frames of that are made from bent ‘Flex rod 11 studs’, thinner middle frame is from ‘Outer cable 8 studs’. Even this was 1 stud smaller than the 9-stud diameter cabin. This has two sad consequences:

-Nose of my M500 is longer and more upward puckering than the real MD500.

-Windscreen closed all options to fix instrument panel to cabin floor. I had to fix instrument panel to forward yaw control trackrod, so it moves 0.5 studs forward/back with yaw control, totally pointlessly.

Otherwise I tried to build the most important avionics instruments there, and realistic layout of aerials and navigation lights.

4 Dimensions of MD500

Height: 21.00 studs / 168.00 mm / 6.61 in, Real size: 3.36 m / 11 ft 0.20 in (with floats: 24.00 studs / 192.00 mm / 7.56 in, Real size: 3.84 m / 12 ft 7.09 in)

Main rotor diameter: 49.00 studs / 392.00 mm / 15.43 in, Real size: 7.84 m / 25 ft 8.46 in

Rotor disc area: 1885.74 sqstuds / 1206.87 sqcm / 187.07 sqinch, Real size: 48.27 sqm / 518.95 sqfeet

Tail rotor diameter: 9.00 studs / 72.00 mm / 2.83 in, Real size: 1.44 m / 4 ft 8.66 in

Distance between main rotor mast and tail rotor axis: 30.00 studs / 240.00 mm / 9.45 in, Real size: 4.80 m / 15 ft 8.86 in

5 Unsolved issues

-5-blade rotor hub cannot tolerate very high centrifugal forces as it depends on resistance of ‘stick with holder’ parts.

-Tail rotor blades are not SNOT and streamlined to adhere to their historic size and shape.

-2 AA-Batteries can only be placed in floats with homemade wiring.

-5th seat is sacrificed for collective-cyclic control mixing linkage.

-Windscreen has 1 stud smaller diameter than optimal and its half-globe form results in too long nose.

-Instrument panel moves 0.5 studs forward/back with yaw control, as there was no space to fix it to cabin floor.

-Horizontal cyclic control trackrods are placed beneath the cabin floor to save space, but it destroys aesthetics, when the helicopter is seen from the bottom.

-Helicopter will fall backward when parked without floats and batteries because of the tremendous weight of PF M-motor, which heavily influences COG. This could be prevented by extending landing skids backward, but then aesthetics, and historical correctness will suffer.

6 References

Assault executive transport helicopter appearing in dogfighting scene is my earlier Bad Guys Escape Helicopter MOC:


Figure 40: Bad Guys Escape Helicopter


Building instructions
Download building instructions (LEGO Digital Designer)

Comments

 I made it 
  September 1, 2014
Quoting Kurt's MOCs Amazing work! The design and execution is flawless. I love your presentation as well: informative and insightful. Keep 'em coming!
Thanks. Another big shot coming at mid September.
 I like it 
  September 1, 2014
Amazing work! The design and execution is flawless. I love your presentation as well: informative and insightful. Keep 'em coming!
 I made it 
  August 19, 2014
Quoting Matt Bace Fantastic work once again. I am always impressed by the compact solutions you come up with to solve the various technical problems in your builds -- some very inspired ideas there.
Thanks, Matt. Now I just working on even more tricky model coming in September (hopefully). Comparing to that, this MD500 is dead simple.
 I like it 
  August 19, 2014
Fantastic work once again. I am always impressed by the compact solutions you come up with to solve the various technical problems in your builds -- some very inspired ideas there.
 I made it 
  August 11, 2014
Quoting Lego 4 Life Looks great! Nice photo editing!
Thanks!
 I like it 
  August 11, 2014
Looks great! Nice photo editing!
 I made it 
  August 10, 2014
Quoting Samuel Sims WOW... :O
Thanks. This is what is called the "WOW effect" in marketing...
 I like it 
  August 10, 2014
WOW... :O
 I made it 
  August 10, 2014
Quoting Solid Snake Brilliant! You truly are a great builder, especially with your level of detail and mechanics in your builds!
Thanks!
Gabor Pauler
 I like it 
Solid Snake
  August 9, 2014
Brilliant! You truly are a great builder, especially with your level of detail and mechanics in your builds!
 I made it 
  August 9, 2014
Quoting Florida Shoooter Amazing! Your work on this helo is exceptional. My lil boy absolutely loves all the technical "drawings" and breakdowns. Thank you for sharing this outstanding helo.
Thanks. I tried to be educational for the kids, giving realistic (but still very strongly simplified) picture about mechanics of helicopters. Nowadays Hollywood just makes too much destruction in engineering thinking of young people.
 I made it 
  August 9, 2014
Quoting Henrik Jensen Congratulations on the third year on MOCpages. Another fine piece of engineering. The 5 bladed rotor head looks convincing, and the model looks smooth and realistic. A few Things I have noticed are: The rotor mast is hardly strong enough when the shaft only goes through the bottom steering wheel. But you can send the complaint to TLG, they must make a steering wheel where the axle can go through. I still see a problem in the cyclic control. The swashplate can only tilt forward or back not left or right. Looking forward to your further development of your helicopter models.
Dear Henrik, thanks for your comment. You really have nose for fine technical details. About your first critics: Yes, the steering wheel does not allow the technic cross axle to go through. But, if you check out my LDD model carefully, I extended main rotor mast upward with a 3 stud long 3.2mm shaft, which goes through both steering wheels. The lower steering wheel connects the small shaft with the 12 stud cross axle of main rotor mast. It is enough strong for such a small rotor. The weakest link in my point of view are the stick with holders connecting blade roots to steering wheels. About your second critics: it is partially true. In the reality, there are 4 cyclic ball joints, while I put there only 2 to save space. Swashplate still can be tilted aside, becuse it is supported by 3 points from downward: 1 central collective sleeve and 2 ball joints. If one ball joint moves up, the other goes down, and collective is fixed, the swashplate will tilt aside. But you are right that this is an unexact and mechanically not very efficient way to tilt swashplate aside. But using 4 cyclic ball joints, back seats and ammo belt are just gone because of lack of space.
 I like it 
  August 9, 2014
Congratulations on the third year on MOCpages. Another fine piece of engineering. The 5 bladed rotor head looks convincing, and the model looks smooth and realistic. A few Things I have noticed are: The rotor mast is hardly strong enough when the shaft only goes through the bottom steering wheel. But you can send the complaint to TLG, they must make a steering wheel where the axle can go through. I still see a problem in the cyclic control. The swashplate can only tilt forward or back not left or right. Looking forward to your further development of your helicopter models.
 I like it 
  August 9, 2014
Amazing! Your work on this helo is exceptional. My lil boy absolutely loves all the technical "drawings" and breakdowns. Thank you for sharing this outstanding helo.
 I made it 
  August 9, 2014
Quoting Centurion Cone Your stuff is insane!
Thanks. Actually I'm getting insane after drawing so many technical drawings. But I wanted it to be educational.
 I made it 
  August 9, 2014
Quoting Sven Jagdmann Congrats on your third MOCiversary and congrats for this excellent piece of engineering. So many functions and details in such a nice model, that's really impressive. I think working this out on LDD needs a lot of patience and time. Perfect!
Thanks!
 I made it 
  August 9, 2014
Quoting Yann (XY EZ) Hey gabor! This is superb! I like reading and watching your mocs because there is so much engineering in it! I wouldn't have the patience to do this on ldd! Fantastic!! 5/5 8-)
Thanks. In fact, if someone learns where the parts are, and have some experience, it is much more fast to build in LDD than in the reality (at least 8 times). What takes dead lot of time is to write it down with nice technical drawings.
  August 9, 2014
Your stuff is insane!
 I like it 
  August 9, 2014
Congrats on your third MOCiversary and congrats for this excellent piece of engineering. So many functions and details in such a nice model, that's really impressive. I think working this out on LDD needs a lot of patience and time. Perfect!
 I like it 
  August 9, 2014
Hey gabor! This is superb! I like reading and watching your mocs because there is so much engineering in it! I wouldn't have the patience to do this on ldd! Fantastic!! 5/5 8-)
 I made it 
  August 9, 2014
Quoting World Of Recreation Nice construction on one of my favourite helicopters, really detailed and functional.
Thanks!
 I like it 
  August 9, 2014
Nice construction on one of my favourite helicopters, really detailed and functional.
 
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