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Star Wars Real-Engineered: Darth Pauler’s X-Wing
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Foldable Tilting X-Wing Multicopter driven by 4 LPF L-motors via RC by 2 LPF2 SmartHubs, with 2 turbo generator range extenders, 1 belt fed 6-barrel rotary gun, 2 Hellfire missiles, 1 Bionicle/Technic pilot in ejector seat (all spring-driven shooting), in Scale 1:10
About this creation
Vertical takeoff
Figure 1: Vertical takeoff
See model in LDD

Vertical-horizontal flight transition
Figure 2: Vertical-horizontal flight transition
See model in LDD

1 Preface for our “Star Wars Real-Engineered” mini-series

It is very clear that no one can make Sci-Fi movie without departing from existing scientific knowledge. However, it can be done in the clever way, like Stanley Kubrick’s “2001 a space odyssey”. Alternatively, it can be done unnecessarily raping very basic laws of Physics valid through the Universe - like in Babylon 5 or in Star Wars - serving the marketing needs of target audience. Our mission is trying to re-create the fanciest Star Wars-gizmos from Lego Technic using strict engineering point of view, based on current or slightly extended technology.

2 The Star Wars gizmo real-engineered: Incom T65 X-Wing Fighter

Incom T65 X-Wing Fighter was designed by Joe Johnston at Industrial Lights & Magic in 1978, strongly inspired by the sleek F-104 Starfighter and then new F-18 Hornet. From the ten thousands of MOCs modeling it, we selected to show Incom T65B X-Wing Fighter by Justin Davies, because it is so perfect, that there is no need to put image of the original movie prop here. One has to born Justin Davies to recreate from Lego the horizontal/vertical tapering of the nose, and keep hexagonal cross-section of the airframe in the meantime:


Figure 3: Incom T65B X-Wing Fighter by Justin Davies

From engineering point of view, X-Wing is totally obsolete and pointless as a military spacecraft intercepting other space crafts. It is well known that George Lucas used WWII Carrier battle footages to model space battles. Real military space crafts and battles predictably will look much less fancy because of the Damned Physics:

1. Manned interceptor is totally pointless, adding intolerable mass and vulnerability of pressure hull and life support systems, seriously limiting mission duration and fast maneuverability in orbit, moreover Artificial Intelligence can almost do the same than human pilot, from tiny fraction of resources.

2. X-Wing airframe would destabilize and break up at atmospheric entry of an Earth-type planet at 8000m/sec (28800 km/h), or it would require disproportionately huge shield. A lifting body airframe would be more appropriate.

3. Space is f*****g big, so most encounters with enemy will be in several hundred thousand kilometers range. Using concentrated laser beam weapon is impractical to intercept a fast maneuvering spacecraft so far away. E.g., if you want to hit something orbiting around the Moon from Earth orbit (384000 km away, which is ridiculously close in Space terms), it takes 1.3 secs to catch any signal from the target and another 1.3 secs to send the beam, because light is not faster (nothing is faster…). So the enemy has 2.6 secs to randomly change course and avoid the beam. Self-guided missiles seem to be more practical space weapons. But, because of lack of dense atmosphere, explosive warheads (like proton-torpedo…) become less effective. Instead of it, releasing array of small kinetic penetrator pins in the proximity of target is much more dangerous, as they are not decelerated by air drag, and can cause huge damage impacting at several 1000m/sec relative speed.

Interestingly, the X-Wing Fighter is not so obsolete and pointless in the role of atmospheric fighter aircraft:

1. X-Wing shape can generate almost as much aerodynamic lift (span efficiency = 1.33) as similar sized biplane wing shape (1.36):


Figure 4: Span Efficiency of non-planar wing shapes

2. Julian Danzer did extensive X-Wing flow simulation using Solidworks in his MSc Thesis:


Figure 5: Flow simulation of X-Wing, front view

One can see that most lifting force is generated in the upper- and lower Vs, while at side Vs airflow is pretty neutral. X-wing is very sensitive to well-faired and separated wing roots, as huge parasitic drag can be generated there at high speed with awkward design (e.g. placing engine nacelles there, Joe…).

3. The most serious shortcoming of X-Wing Fighter is complete lack of rudder/elevator stabilization surfaces. Ramy RC built an RC X-Wing Fighter with small twin rudder and elevator placed in the blast of 4 electric ducted fan engines, plus S-foils were replaced with real aero foil, and the aircraft flew pretty well.

4. Using X-Wing was considered at Sukhoi Shkval 1 supersonic VTOL tail-sitter interceptor aircraft designed by Rolan G. Martirosov:


Figure 6: Sukhoi Shkval 1 supersonic VTOL tail-sitter interceptor aircraft

The well-designed concept remained paper project because advent of ICBMs made nuclear bombers and their high speed interceptors obsolete.

5. The most similar real aircraft to X-Wing Fighter up to day is Burt Rutan's Quickie using tandem X-Wings and no separate elevator:


Figure 7: Burt Rutan's Quickie

It is pretty fuel efficient lifting 2 persons in enclosed cockpit using a 23hp mini engine, at the price of limited climb rate.

6. The most similar multicopter drone to X-Wing Fighter is XCraft PlusOne tail-sitter tilting wing quadcopter:


Figure 8: XCraft PlusOne

It can reach much higher level speed and range than conventional quadcopter drones (capable of tracking a motorbike), but landing is more difficult, especially in cross-wind and rough terrain.

To justify using the mechanically troublesome folding X-Wings, in our current model, we extended tilting wing quadcopter concept into manned attack aircraft, reaching the following contradicting aims TOGETHER:
1. Vertical Take Off Landing
2. High level speed around 300 knots
3. Foldability on shipboard + unassisted opening from enclosed cockpit
4. Safe landing in adverse weather conditions/rough terrain

4 Our Tilting X-Wing Multicopter (TXWM)

Our TXWM MOC is a piece of concept art, but it is strictly tied to real engineering principles described above. It consists of 2122 bricks, resulting 8 power functions, 21 manual functions and 40 non-working features in scale 1:10:

Functions overview of TXWM
Figure 9: Functions overview of TXWM
See model in LDD

As real quadcopters are built from high tech carbon fiber reinforced composite materials instead of ABS bricks, this MOC very clearly exceeds the physical limits of Lego bricks (even we tried our best to reinforce it). Therefore, its playability is almost nil, and it serves as demonstration of a concept.

TXWM in level flight animated
Figure 10: TXWM in level flight animated
See model in LDD

Level flight configuration of TXWM used at high speed includes 4 small wings with 27° sweepback openable into in 45° anhedral/dihedral, equipped with wingtip-mounted, foldable, 4-blade, electric driven propellers, wingtip mounded castor landing wheels, and moveable aileron surfaces. We opted for T-tail to create minimal interference with downwash of wingtip-mounted propellers. T-tail contains rudder/elevator surfaces controllable from cockpit.

Cutaway view of TXWM in vertical-horizontal transition
Figure 11: Cutaway view of TXWM in vertical-horizontal transition
See model in LDD

X-Wings are tiltable from horizontal to vertical with the help of 2 independently moveable ‘7-stud turntables’ controlled from cockpit with crank handles + worm gear. This way TXWM can function as a VTOL quadcopter, performing slow hovering flight. At hovering mode, conventional quadcopter controls are used, rpm of pairwise contra-rotating propellers are continuously altered by flight computer. This consumes lot of energy as relatively large propellers of a manned aircraft have high inertial torque. As current battery technology is still far from providing sufficient energy source for that, conceptually we propose a hybrid drive: Besides small Zinc oxide-Silver rechargeable puffer batteries useable in silent mode/emergency landing for 60-180 seconds, 2 micro turbine generators (often called turbo-generator e.g.: Capstone C65 Micro turbine generator) are used as range extenders. At vertical hovering mode, downwash of propellers on wing surfaces generates backward force, but this is counterbalanced by thrust of jet exhaust nozzles of turbo-generators and backward flipping of aileron surfaces. Therefore hovering mode is inherently energy wasting, and TXWM is not suitable for long sustained hovering.

Animated cutaway view of TXWM in vertical-horizontal transition
Figure 12: Animated cutaway view of TXWM in vertical-horizontal transition
See model in LDD

High speed level flight is much more energy efficient, as propellers maintain constant rpm, helped by backward thrust jet exhaust nozzles of turbo-generators. All steering is made with rudder/ elevator/ aileron surfaces plus small changes in left/right wing tilting as roll control. But, as a backup system – if there is any problem with mechanic rudder/ elevator/ ailerons/ wing tilting – rudimentary pitch/yaw/roll control can be done with altering rpm of propellers even in level flight. There is a phenomenon at all tilt-wing aircrafts called “Yaw-roll shift”: while pitch control remains the same regardless vertical/horizontal flight regimes, yaw- and roll controls will be flipped, so flight computer should compensate this.

Folded view of TXWM
Figure 13: Folded view of TXWM
See model in LDD

One could see in the introduction that X-Wing is not the most effective non-planar wing shape, while it is rather complex mechanically. We still opted for it because of its excellent foldability. With X-Wings tilted vertical, and wings/propellers folded, TXWM gets boxy shape, allowing very compact shipboard storage. On a helicopter deck of a small littoral gunboat, several TXWMs can be stored and launched in the same time:

Launching TXWM from helicopter deck of littoral gunboat
Figure 14: Launching TXWM from helicopter deck of littoral gunboat
See model in LDD

Left/right wings of TXWM can be opened with left/right cranks placed at pilot’s shoulder via Worm+Z8 gear mechanics, and propellers can be flipped opened with the help of leading edges of wings, starting their LPF L-Motors at low rpm. TXWM with wings and propellers opened can make slow taxiing on smooth ship deck unassisted in any direction (even backward or sideways). This is because wings also function as spring struts for landing gear. Their sweepback can be changed between 23.5°and 27°elastically with an internal parallelogram linkage mechanics. Moreover, wingtip castor wheels can turn in any direction. Therefore, just spinning the two rear propellers at moderate rpm will result in moderate leaning forward and slow taxiing forward.

TXWM in vertical-horizontal transition
Figure 15: TXWM in vertical-horizontal transition
See model in LDD

There is an intermediate flight regime between 100 km/h and 270 km/h when X-Wings are tilted forward 45°, and TXWM behaves like a tiltrotor multicopter. Above 270 km/h speed, even the small X-Wings will generate sufficient lift.

TXWM in level flight
Figure 16: TXWM in level flight
See model in LDD

Armament of TXWM consist of 1 30mm, 6-barrel, belt-fed Rotary Gun and 2 Hellfire missiles placed underbelly (all are modeled spring driven shooting). Also, there are 10 jetissonable IR decoys/chaffs to divert IR-homing missiles, modeled as non-working feature.

TXWM attacking M-777 Howitzer battery
Figure 17: TXWM attacking M-777 Howitzer battery
See model in LDD

One critical design feature is placement of air intakes and turbo-generators. Most conveniently, they could be placed at wingtips, but this would overstress the already highly loaded wing root mechanics. Also it would increase the rotational inertia of the airframe, which is big disadvantage in dogfight. Therefore turbo generators are placed in the tail, above each other, and their 4 air intakes are inter-connected to avoid tilting X-Wing to block airflow at different flight regimes.

TXWM in battle turn
Figure 18: TXWM in battle turn
See model in LDD

The heavy gun barrels were placed as close to Center Of Gravity (COG) of the craft as possible, to allow being stabile gun platform both in horizontal and vertical flight regimes.

TXWM fires rotary gun in hovering
Figure 19: TXWM fires rotary gun in hovering
See model in LDD

TXWM is designed for very austere battlefield servicing facilities. The wide track landing gear enables it to land at rough terrain in strong crosswind conditions.

Reloading TXWM
Figure 20: Reloading TXWM
See model in LDD

Jet fuel, ammo belt of Rotary Gun, and Hellfire missiles can be reloaded by ground crew from small hand-pulled carts.

Reloading TXWM animated
Figure 21: Reloading TXWM animated
See model in LDD

At TXWM, we did quite design effort to create the smallest possible enclosed cockpit with openable canopy for a Bionicle/Technic pilot figure in scale 1:10.

Ejector seat deployed
Figure 22: Ejector seat deployed
See model in LDD

Against Hollywood movies, in the reality enemy has the nasty habit of shooting back. Therefore, all military craft worth as much as it can save crew in emergency: a new aircraft can be manufactured in matter of weeks, but it takes 18-21 years to manufacture a new pilot. As TXWM is not capable of any kind of dead engine crash landing, we had to equip with a very compact (16×5×10 studs) spring-driven ejector seat to create reasonable margin of safety. We created rescue parachute as non-working feature in a separate submodel.

Parachute opened
Figure 23: Parachute opened
See model in LDD

5 Description of Flight Systems of TXWM

*This part is technical. If you are not familiar with scientific background, you can check out Basic Principles of Quadcopters, Wikipedia and
Persson et al. Design and Control of an Experimental Tiltwing Aircraft, NASA, 2017

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

***Bricks of TXWM are color-coded by their function:
- Yellow: Manual handles of working functions, Fuel lines, Combustion chambers
- Gray/Black: Static parts
- White: Dynamic parts
- Blue: Ejector seat
- Orange: PF Electric lines, Missiles trigger
- Dark green: Explosive charges
- Yellow: lubricant tank
- Red: Fire extinguishers, Rotary Gun trigger

TXWM systems overview
Figure 24: TXWM systems overview
See model in LDD

5.1 Drivetrain



Drivetrain of TXWM
Figure 25: Drivetrain of TXWM
See model in LDD

We modeled conceptual hybrid drive from Lego with the help of (D1) 4 LPF L-Motors RC-controlled via (D2) 2 LPF2 SmartHubs, which serve also as fake jet fuel tanks. (D5) Zinc oxide – Silver battery and (D7) 2 micro turbine range extenders are added as non-working features. Besides automatic control of motors in multicopter mode by (D18) flight computer, there are manual controls in cockpit: (D16) pitch/roll control joystick, (D17) throttle, (D19) yaw control pedals (all are non-working features).

5.2 X-Wing Folding

Wing opening of TXWM animated
Figure 26: Wing opening of TXWM animated
See model in LDD

Left/right pair of wings can be opened from 11° to 45° by rotating left/right (F1) cranks placed at pilots shoulder at 272°. They drive (F2) left/right worm gear axles, which rotate (F3) wing root shafts equipped with Z8 gears. It goes until (F6) limiter hits (F4) worm gear axle bearing, and (F2) worm gear axles get jammed, securing wings in open position. At wing tilting, (F2) jammed worm gear axles will drive (F1) cranks back, to prevent opened wings get loosen.

Wing folding mechanics of TXWM
Figure 27: Wing folding mechanics of TXWM
See model in LDD

5.3 X-Wing Tilting

Wing tilting mechanics of TXWM animated
Figure 28: Wing tilting mechanics of TXWM animated
See model in LDD
Pilot can control 0°..+90° wing tilting from cockpit with 14 rotations of (T1) wing tilting cranks, driving (T4) 7-stud turntables via (T2) worm + (T3) Z8 gear combo. Fine adjustment of left/right wing tilting can serve as left/right roll control.

Wing tilting mechanics of TXWM
Figure 29: Wing tilting mechanics of TXWM
See model in LDD

5.4 Rudder/Elevator Controls

Rudder/Elevator Controls of TXWM animated
Figure 30: Rudder/Elevator Controls of TXWM animated
See model in LDD

As the central control joystick controls rpm of 4 electric motors, performing pitch + roll control at hovering, and pitch + yaw control in level flight, mechanic elevator control had to be placed somewhere else. Therefore we designed (D19) combined rudder/elevator (so called: ruddevator) pedals. They are connected with innovative mechanics at the tail to create T-tail with working controls from a dead simple 1-piece cast TLG part ‘Rudder 2×12×8’, while keeping it smooth and streamlined. The trick is that (R9) rudder surface serves also as trackrod actuating the (R12) elevator surface. (R8) rotating/tilting crosshead actuated by (R4) trackrods arriving from (D19) ruddevator pedals decomposes control inputs into turning of rudder surface and lifting/depressing of elevator surface.

Rudder/Elevator Controls of TXWM
Figure 31: Rudder/Elevator Controls of TXWM
See model in LDD

5.5 Landing Gear

Wingtip castor wheel landing gear of TXWM animated
Figure 32: Wingtip castor wheel landing gear of TXWM animated
See model in LDD

The current landing gear struts solution is heavily dictated by limitations of Lego. First we experimented with placing shock absorbers directly between electric motors and castor wheels, but they were very bulky and not really streamlined. In the meantime, sweepback of wings required to connect (L1)forward/ (L2)rear wing spars into a parallelogram-shaped planar linkage, and left many hollow space inside wing ribs created from (L4) ‘Technic beam 1×1×5’ parts. So it was easier and more streamlined solution to create elastic landing gear strut from this linkage. Sweepback of wing can change from 23.5° to 27°, and (L5) spring from ‘Shock absorber extra hard’ forces it to 27°. A rough landing presses the wing into 23.5° sweepback, compressing the spring. Moreover (L4) wing ribs are fixed to (L1) forward spar, but can slide on (L2) rear spar, and after reaching 23.5°, they start to jam sliding of rear spar, absorbing lot of impact energy. This solution affects somewhat negatively structural stiffness and aerodynamics of the wing, but resulted elastic landing gear in tolerable size. In real engineering, we would use fixed sweepback wing and reasonably small oleo-strut at landing gear, of course.

Wingtip castor wheel landing gear of TXWM
Figure 33: Wingtip castor wheel landing gear of TXWM
See model in LDD

5.6 Navigation Systems

Navigation Systems of TXWM
Figure 34: Navigation Systems of TXWM
See model in LDD
We modeled the basic avionics of light military aircrafts, with night vision IR camera dome and small gun aiming radar placed in the nose. the cockpit is so small, that there is no place for conventional dial instruments, there are 2 multifunction displays of flight computer as instrument panel.

5.7 Egress Systems

Overview of Egress Systems of TXWM
Figure 35: Overview of Egress Systems of TXWM
See model in LDD

Ejector seat is operated by (E1) 6 8×16mm steel springs pulled on ‘Technic axle 5M’ launch rails compressed. It is arrested by (E2) hook held by (E3) slideable locking pin in the cockpit floor, which can be pulled backward 0.5 studs by (E4) trigger levers placed at pilot’s shoulder. (E8) Pressurized Oxygen bottle is fixed to belly part of (E7) harness. (E5) Parachute box is in the 45° backward tilted back plate.

Ejector Seat of TXWM animated
Figure 36: Ejector Seat of TXWM animated
See model in LDD

Cockpit canopy can slide upward and rotate with the help of (E14) rod, which has (E16) hinge at it its top, fixed to (E15) front frame of canopy. This solution enables canopy to be opened in very limited space (e.g. when TXWM is folded), but before triggering ejector seat, it has to be jettisoned manually, loosing valuable time.
As pilot can make only minimal movements in the confined cockpit, there are 3 pairs of built in fire extinguishers: (E12) for instrument panel, (E18) for cockpit/fuel tank, (E19) for ammo and engines.

Ejector Seat of TXWM
Figure 37: Ejector Seat of TXWM
See launched model in LDD
See locked model in LDD

6 Armament of TXWM

Armament of TXWM
Figure 38: Armament of TXWM
See model in LDD

TXWM carries relatively heavy underbelly armament compared to its size. Aerodynamically, hardpoints for weapon fixing pylons could have better placement in side Vs of X-wing, where airflow is almost neutral. But then the pylons should tilt with the X-Wing, rendering the armament hard to use in hovering mode. Belly placement of armament is not affected by X-Wing tilting, but disturbs dense airflow more.

6.1 Spring driven shooting , belt-fed, 6-barrel, 30mm Rotary Gun

Gatling-type rotating barrels have no practical relevance in spring-driven weapons. However we could see so many unworkable Gatling mockups in several MOCs that the modeling challenge was there to design workable one. Barrels are not rotated automatically, but it will not disturb spring-driven shooting.

Rotary Gun of TXWM animated
Figure 39: Rotary Gun of TXWM animated
See model in LDD

(W2) 3.5×72mm Rotating barrels are made from 6×3 ‘Technic connector peg 3M’ parts (drilled up to 3.5mm inner bore from 3.2mm). Projectiles are made from ‘Screwdriver’. They are fixed into cavities of (W14) ammo belt made from echeloned ‘Technic beam 2×1×1’ + ‘Connector peg with knob’ (drilled up to 3.5mm inner bore) + ‘Bracelet upper part’ with the help of a tiny drop of molten wax, which can break easily under the shock of shooting. Belt is advanced by (W10) anker-type loading arm equipped with (W13) belt catch, (W11) forward knob and (W12) rear knob. At charging, (W7) rotating bolt made from ‘Rapier’ moves 24mm back, compressing (W9) 2 8×16mm steel propellant springs from ‘Shock absorber’, and tilting loading arm 10° downward by its rear knob. Hence, belt catch moves belt 8mm downward, placing new projectile in line with charged bolt (exact alignment is resolved by (W3) aligner knob, clicking into groove of ‘Bracelet upper part’ on belt). At firing, advancing bolt shoots actual projectile through barrel, locks belt in actual position, and tilts loading arm 10° upward hitting its forward knob. Therefore, belt catch moves up 8mm and clicks into new position on belt. Then the firing cycle is repeated.

Firing Cycle of Rotary Gun of TXWM
Figure 40: Firing Cycle of Rotary Gun of TXWM
See model in LDD

6.2 Spring driven shooting AGM-114 Hellfire Missile

AGM-114 Hellfire is a Fire-and-Forget Air-to-Surface Missile with semi-active laser homing produced by Lockheed Martin. Its original purpose was Anti-Armor, but in recent War of Drones in Iraq and Afghanistan they are mostly used against commanders of rebel forces and all kind of vehicles.

AGM-114 Hellfire Missile launch animated
Figure 41: AGM-114 Hellfire Missile launch animated
See model in LDD

Our model is propelled by 4 propellant spring from TLG part ‘Shock absorber’ and launched from (W28) launch rail/safety pin made from ‘Cross axle 16 studs’. Missile is fixed with (W32) sliding ears on the rail. (W29) trigger arm locks missile and keeps propellant springs compressed with the help of (W31) spacers. If safety pin is pulled backward 1 stud, it allows springs to push trigger arm upward, so the missile and springs can fly out. The missile has a “spinal cord” made from ‘Outer cable 144mm’ to prevent it falling apart by the shock of launch. Short steering/stabilizer surfaces of Hellfire are modeled with TLG parts ‘Wall element 1×2×1’.

Firing Cycle of AGM-114 Hellfire Missile
Figure 42: Firing Cycle of AGM-114 Hellfire Missile
See model in LDD

7 Dimensions of TXWM

3 Plane view of TXWM in hovering and level flight modes
Figure 43: 3 Plane view of TXWM in hovering and level flight modes
See hovering mode model in LDD
See level flight mode model in LDD

- Length: 68.00 studs / 544.00 mm / 21.42 in, Real size: 5.44 m / 17 ft 10.04 in
- Folded with: 22.50 studs / 180.00 mm / 7.09 in, Real size: 1.80 m / 5 ft 10.83 in
- Folded/hovering height: 28.00 studs / 224.00 mm / 8.82 in, Real size: 2.24 m / 7 ft 4.13 in
- Wing span: 38.00 studs / 304.00 mm / 11.97 in, Real size: 3.04 m / 9 ft 11.61 in
- Wing spar length: 16.00 studs / 128.00 mm / 5.04 in, Real size: 1.28 m / 4 ft 2.36 in
- Wing chord: 8.25 studs / 66.00 mm / 2.60 in, Real size: 0.66 m / 2 ft 1.97 in
- Wing sweepback: 23.5°..27°
- X-Wing anhedral/ dihedral: 45°
- Total wing surface: 448.00 sqstuds / 286.72 sqcm / 44.44 sqinch, Real size: 2.87 sqm / 30.82 sqfeet
- Total effective wing area: 353.78 sqstuds / 226.42 sqcm / 35.10 sqinch, Real size: 2.26 sqm / 24.34 sqfeet
- Elevator span: 25.00 studs / 200.00 mm / 7.87 in, Real size: 2.00 m / 6 ft 6.69 in
- Elevator chord: 3.00 studs / 24.00 mm / 0.94 in, Real size: 0.24 m / 0 ft 9.45 in
- Wing spar - elevator spar distance: 28.00 studs / 224.00 mm / 8.82 in, Real size: 2.24 m / 7 ft 4.13 in
- Rudder height: 9.00 studs / 72.00 mm / 2.83 in, Real size: 0.72 m / 2 ft 4.33 in
- Rudder chord: 7.00 studs / 56.00 mm / 2.20 in, Real size: 0.56 m / 1 ft 10.04 in
- Airframe width: 10.00 studs / 80.00 mm / 3.15 in, Real size: 0.80 m / 2 ft 7.48 in
- Airframe height: 11.00 studs / 88.00 mm / 3.46 in, Real size: 0.88 m / 2 ft 10.63 in
- Ground clearance of airframe: 8.00 studs / 64.00 mm / 2.52 in, Real size: 0.64 m / 2 ft 1.18 in
- Propeller diameter: 23.00 studs / 184.00 mm / 7.24 in, Real size: 1.84 m / 6 ft 0.39 in
- Total propeller disc area: 1661.90 sqstuds / 1063.62 sqcm / 164.86 sqinch, Real size: 10.64 sqm / 114.34 sqfeet
- Total width with wings and propellers open: 58.00 studs / 464.00 mm / 18.27 in, Real size: 4.64 m / 15 ft 2.56 in
- Total height in level flight: 49.00 studs / 392.00 mm / 15.43 in, Real size: 3.92 m / 12 ft 10.24 in

8 Unsolved issues of TXWM

TXWM has typical teething problems of an innovative concept without real predecessors:

8.1 Inherent deficiencies of TXWM concept

1. There is no way of dead engine crash landing TXWM, as small X-Wings cannot generate sufficient lift at low speed, and in quadcopter mode, propellers cannot make auto-rotation, like helicopter rotors. Ballistic parachute could be used to save the whole craft, but there are too big propeller blades too close to entangle and cut parachute ropes jettisoned from a rolling, destabilized aircraft. Therefore, civilian version of such a concept will never get FAA-certificate.
2. Even in real engineering, large sized multicopters face with serious limitations. As their steering and stabilization is based on continuous acceleration/deceleration of propellers, energy consumption highly depends on propeller torque. If size of a propeller is doubled made from the same material, at same rpm, its lifting force will be 4 times more, but its torque will be 32 times more! (Mass will be 8 times more, rotational speed is doubled but it effects torque on the second power, so 8×2×2=32). This problem could be overcome with using several dozens of small propellers, which also have positive effect on redundancy. But it adds structural complexity, moreover small-diameter propellers are less effective aerodynamically because of the higher downwash airspeed required to maintain same lifting force. Therefore TXWM is not suitable for sustained hovering operation because of the high energy consumption.
3. In hovering, wings would generate backward force in propeller downwash, which should be neutralized by aileron setting and forward thrust of turbo-generators jet exhaust, but this solution again wastes energy.
4. Hard to synchronize mechanic and electronic steering controls because of yaw/ roll shift phenomenon (it is common problem for all tilting wing aircrafts).
5. There are more effective non-planar wing forms for VTOL aircrafts than X-Wing (see referenced scientific reading material), but they are not foldable.
6. Hybrid drive (Jet fuel tank + micro turbine + generator + puffer battery + electric motor) is too heavy for such a small aircraft.
7. Mechanics of X-Wing roots requires light, very high tensile strength, very expensive materials (e.g. turntables should be made from forged Titanium), this is simply unrealistic for such a small aircraft.

8.2 Deficiencies of TXWM MOC

1. We did not really take care about centrifugal force tolerance of propellers. Most probably propeller blades will fly away at high rpm. Torque-tolerant propellers would be bulkier and less aerodynamic from current TLG parts.
2. Wing folding mechanism will most probably break off by vibration of LPF L-motors.
3. We could not resolve modeling control links for aileron surfaces on wings, they are moving freely. Although roll control can be solved by small alterations in left/right wing tilting, ailerons have important role to stabilize the craft during hovering (propeller downwash generates backward force on wing’s airfoil).
4. Wing tilting and wing folding is manual. RC control would require more LPF2 SmartHubs and control channels connected with TLG Micromotors. But they simply cannot fit in such a limited size.
5. Wing root with folding mechanism is bulky and not streamlined, which would cause huge parasitic drag.
6. Longer wings would be better, with changeable anhedral/ dihedral angles during transition from vertical hovering into level flight (smaller anhedral/dihedral would be more effective in level flight, while 45° is ideal for multicopter mode). Current mechanics will very clearly insufficient for this. There should be separate linear actuator for each wing for continuous changing of anhedral/dihedral angle.
7. Ideal placement of air intakes would be at underbelly or at side of cockpit to avoid disturbance of airflow by X-Wing, but there was not enough space for this.
8. Ejector seat can stuck easily during launch because of the short launch rails, automatic dropping of canopy is not solved.

9 References

1. In the ground attack scene, our earlier M777 Light Towed Howitzer MOC was destroyed:

M777 Light Towed Howitzer
Figure 44: M777 Light Towed Howitzer
See model in LDD

2. The enemy helicopter in the ejector seat deployment scene is our earlier Light Attack Compound Helicopter MOC:

Light Attack Compound Helicopter
Figure 45: Light Attack Compound Helicopter
See model in LDD

3. In the dogfight scene, the opponent is our earlier Ultralight Coaxial Attacker Helicopter MOC:

Ultralight Coaxial Attacker Helicopter
Figure 46: Ultralight Coaxial Attacker Helicopter
See model in LDD


Building instructions
Download building instructions (LEGO Digital Designer)

Comments

 I made it 
  May 8, 2018
Quoting Titus D. just one question, why do most of your models have almost no leg room?
It is a nasty trick to save lot of bricks (and video memory...). As I ususally build with 1:10 scaled Bionicle/Technic figures, it results in cumbersome material requirement. Even more difficult problem is, that windscreens, cover parts, streamlining bricks mostly designed to minifig scale, so they are very small in this scale. Sitting position of my figures are really a medieval torture, but this way they can be sqeezed into reasonable sized section of an 8-wide cockpit, eating 15×7×10 studs. My Light Assault Compound Helicopter (LACH) MOC (visible in the references) has normal leg space - and it is more than twice as long as the current MOC, containing 9200 bricks instead of 2122. Big difference...
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  May 8, 2018
just one question, why do most of your models have almost no leg room?
 I made it 
  May 5, 2018
Quoting Henrik Jensen I almost missed your awesome tilting X-wing multicopter in all the DA3 stuff, and it`s certainly a very advanced flying machine! Very entertaining to scroll through the post with all the animated gifs, a true plethora of quirky ideas!
Thanks. I am happy to see that DA3 participants re-vitalized MOCPages.
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  May 5, 2018
I almost missed your awesome tilting X-wing multicopter in all the DA3 stuff, and it`s certainly a very advanced flying machine! Very entertaining to scroll through the post with all the animated gifs, a true plethora of quirky ideas!
 I made it 
  April 27, 2018
Quoting Lee Blume Simply awesome Gabor Pauler. Unsurpassed detail to die for.
Thanks.
 I made it 
  April 27, 2018
Quoting Jesse Horn That is really Awesome man, Your an artist!
Thanks.
 I like it 
  April 27, 2018
That is really Awesome man, Your an artist!
 I made it 
  April 27, 2018
Quoting Nick Barrett A great idea, well worth exploring, and it produces a pretty awesome machine.
Thanks. I'm already thinking about an aerodynamically more acceptable version. This was a only tiltrotor drone little bit hacked into a rigid wing aircraft, but not designed to that from scratch. And rigid wing aircrafts are more difficult and sensitive beasts than multicopters...
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  April 27, 2018
A great idea, well worth exploring, and it produces a pretty awesome machine.
 I made it 
  April 26, 2018
Quoting Mark B. As always, an incredible attention to detail in the design. The wing rotation and folding mechanisms are some beautiful engineering, as is the rotary gun.
Thanks.
 I like it 
  April 26, 2018
As always, an incredible attention to detail in the design. The wing rotation and folding mechanisms are some beautiful engineering, as is the rotary gun.
 I made it 
  April 26, 2018
Quoting BATOH rossi you can always overcome yourself! beautiful simulation of the lift capacity ... but during the transition from vertical to horizontal attitude, the turbulence must be a real nightmare!
Thanks. All tiltwing aircrafts are engineering/aerodynamic nightmares by definition. Think about that the Canadian Dynavert tiltwing plane was operational as prototype with numerous flights in 1968. It took 32 years until Boeing V-22 Osprey was put into real military service around 2000, after 20 years of developement.
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  April 26, 2018
you can always overcome yourself! beautiful simulation of the lift capacity ... but during the transition from vertical to horizontal attitude, the turbulence must be a real nightmare!
 I made it 
  April 26, 2018
Quoting P. Andrei Impressive, maybe a tad on the small side compared to the figs.
Thanks. Well, it is a small ultralight craft (not the same size class as original X-Wing), because multicopters tend to be less and less efficient increasing their size. The reasons in physics are described above.
 I like it 
  April 26, 2018
Impressive, maybe a tad on the small side compared to the figs.
 I made it 
  April 26, 2018
Quoting Doug Hughes Dude you always kill it with awesome details and specs and drawings, wow!!
Thanks.
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  April 25, 2018
Simply awesome Gabor Pauler. Unsurpassed detail to die for.
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  April 25, 2018
Dude you always kill it with awesome details and specs and drawings, wow!!
 I made it 
  April 25, 2018
Quoting Seaman SPb Wow! Fantastic work! And very beautiful! How do you manage to make them?
Thanks. Well, I played around with the idea for a while. It is the second version of the MOC, and it took one month to prepare.
 I like it 
  April 25, 2018
Wow! Fantastic work! And very beautiful! How do you manage to make them?
 I made it 
  April 25, 2018
Quoting Zach Sweigart That is a fun, and unique design! I love it! Very different interpretation of an X-Wing. I'm digging it.
Thanks.
 I like it 
  April 25, 2018
That is a fun, and unique design! I love it! Very different interpretation of an X-Wing. I'm digging it.
 
By Gabor Pauler
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