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Cockpit controls with ejector seats (working)
Working 4-channel twin cockpit controls and ejector seats for heavy battlefield helicopters in scale 1:20
About this creation
Visit my Lego helicopters blog

1.Project SKYTANK

1.1.Controls

1.1.1.Cockpit controls and ejector seats

1.1.1.1.Introduction

In many land vehicle MOCs (eg. sportcars, trucks, crawlers) we can see excellent, detailed, functional cockpits: steering, brake, gear shift, throttle etc. TLG also provides nice examples (Except the last Unimog model, where steering wheel is not connected to steering mechanism because of tiltable cockpit. Thats pity, it could be solved with 2 extra universal joints).

However, in aircraft/helicopter MOCs functional cockpit controls are infrequent, at TLG models they are simply non-existent. This is because they are less well known, more complex, and MOCers may have a fear that working controls can't be build in reasonable compact size to fit in a cockpit.

The situation is more dire at ejector seats. They are important parts of majority of military aircrafts since the end of WWII, being an engineering marvel and almost a small aircraft themselves, packed in a large backpack-size. They have solid-fuel rocket engine with at least two parachutes, they stabilize themselves, they have autopilot to open parachute with inconscious pilot, they provide oxygene and survival kit, they have navigation beacons to help SAR units to find downed pilots.



When I searched the term "ejector seat" on MOCpages I found more James Bond's agent cars equipped with it than aircrafts (you can check it yourself), but there are exceptions with some nice solutions even in scale 1:50: E.g. SU-27 page Moreover, nobody attemted to make functional MOC ejector seat.

1.1.1.2.Basic concept of own design

Therefore, I created a compact, self contained cockpit controls module for airplanes/helicopters in scale 1:20 (roughly Technic Figure scale), with working 4-channel twin controls (pitch, roll, yaw, throttle) and 2 functional ejector seats in side-by-side alignment. The module has dimensions of 10 studs long, 9 studs wide, and 9 studs tall.



As original lego Technic figures are discontinued and not in Lego Digital Designer, I demonstrate my design with 1:20 scaled pilot figures from my earlier MOC of Lego Technic figures replacement. They are 12 studs tall with 3 studs wide 1.5 studs tchick body torso +1 stud tchick arms. Seated, they are 7 studs tall and 6 studs (with legs extended)/5 studs (legs down) long. As original Technic Figure was also 12 studs tall, but had only 2 studs wide, feminine type of body, it could fit easily in the seats. Non-caucasian raced guys are somehow underrepresented in TLG sets, they are mostly at licensed themes. Therefore, I selected an African American pilot (Col. Jackson) and Hispanic one (Lt. Col. Rodriguez) to show that we are against racial discrimination.

1.1.1.3.Four-channel twin controls

(Notes: In the forthcoming technical description, parts are referenced by code numbers can be found in attached figures. See the attached Lego Digital Designer LXF file for building instructions. If you do not understand, how do helicopter controls work, check out Aviastar site for easy-to-understand explanation)



Channel 1: Pitch control: Forth/back movement of C1, C2 yokes are synchronized by C5 pitch synchronizer shaft of pivots of yokes. This movement causes underseat C7 left/right cyclic control levers raise/depress together, pulling/pushing C8 left/right vertical pushrods together, switching on/off C9 left/right cyclic control pushbuttons together.

(Note: We show here an example of a larger sized craft with fly-by-wire controls, where there is no mechanical connection between cockpit controls and control surfaces. Pushbuttons transmit steering signals to a Lego Mindstorms central unit placed under cockpit in lower fuselage, which computes optimal settings of control surfaces and controls them by Mindstorms servo motors. In smaller and more simple models, C7 levers can be extended backward, C8 pusrods can go upward, forming mechanical connection with control surfaces)

Channel 2: Roll control: Left/right movement of C1, C2 yokes are synchronized by C6 roll synchronizer trackrod. This movement causes underseat C7 cyclic control levers rotate, pulling/pushing left/right C8 vertical pushrods echeloned, switching on/off C9 left/right cyclic control pushbuttons echeloned.

Channel 3: Yaw control: Echeloned movements of C3 yaw control pedals are synchronized by C10 yaw pedal actuator sliding block, which slides forward/back, rotating C13 yaw lever up/down by C12 ball joint. It will pull/push C14 vertical yaw pushrod an turn on/off C15 yaw pushbutton.

Channel 4: Collective control/engine throttle: Pulling up C4 collective lever, it will rotate around C16 pivot and push down C17 pusrod and C18 throttle pushbutton.

1.1.1.4.Ejector seats

Ejector seats add plus 2 studs lenght to a normal Lego technic seat, and in 4 studs width 8 studs height they perform all important functions:

(Note: Ejected parts of seats are color-coded in dark blue, static parts of seats are grey, all manual handles are yellow, static parts of airframe are red, bodies of pilots are green)



In the reality, ejector seats are propelled by solid-fuel rockets, but it is not an option in Lego, as ABS material will not tolerate high temperature and pressure. Therefore, we simulate rocket boosters with E2 ejector springs. They are held compressed by E4 spring lockig rails, which also hold seat in its place. Rails can be tilted left/right 0.5 studs to release E2 ejector spring.



When pairs of E3 deployment levers are pulled down by both hands of pilot together into horizontal position, they press wedges behind E4 rails, tilting them, which disengages E2 ejector springs. E4 rails take place between the gap of seat and E1 parachute box even in their open position, so they still lead ejecting seats vertically, when seats break through cockpit canopy.



E1 boxes with backward-opening lids store the parachutes. E5 shoulder straps fix pilots into seats.

1.1.1.5.Instrument panel

Instrument panel has C19 smaller leg consoles, C20 large middle console, C21 mutlifunctional displays and C22 head-up displays. Moreover, it does not increase basic dimensions of the module, and it has rounded corners to fit in streamlined cockpits easier

1.1.1.6.Example for deployment of ejector seats

At 1930 ZULU, departing from Baghram Base, Afghanistan, their helicopter was hit by an RPG of rebels. The explosion tore down left leg of Lt. Col. Rodriguez, and a shell fragment hit his belly.



Before loosing his consciousness by intense loss of blood, he pulls down deployment levers and his seat is ejected from the blazing aircraft.



1.1.1.7.Unsolved problems and shortcomings

- Overhead deployment levers were used in older type of ejector seats. Their disadvantages are disturbing all-round sight of pilots, and the need of 2 working hands to trigger them. More modern seats have trigger between legs, and a separate emergency trigger at right armrest of seat. I opted for overhead triggers to save space.

- There are no leg restraint straps in seat, so pilots legs can be broken at launcing by intense acceleration

- Real ejector seats has 5-point safety belt straps. I tried to model it, but it was hard. TLG manufactures shoulder straps in minifig scale (1:36), but they cannot be flexed in LDD with flex tool. So I was forced using shorter type of flexible chains, which do not look very nice (they give a distinctive electric chair-look for the seat) and are not very compact. Moreover, they do not really hold pilot figure in position. So I cheated a little bit using rebuildability of my Lego Technic replacement figure: in its original design, male genitals were modelled by "tap" parts. Here I replaced them to "T-link" parts, having the pilots an extra stud extending downward in sitting position, by wich they can be fixed to seats safely.


Building instructions
Download building instructions (LEGO Digital Designer)

Comments

 I made it 
  July 23, 2013
Quoting Matt Bace Wow, this is pretty impressive! I'd love to see it built into a complete aircraft.
Currently, it is under rebuilding. Originally I planned to build a large battlefield helicopter in scale 1:20, but finally shifted to scale 1:10 (rotor diameter: 147 studs /approx. 1.2m). Currently I am working on cockpit canopy and Martin-Baker ejector seats.
 I like it 
  July 23, 2013
Wow, this is pretty impressive! I'd love to see it built into a complete aircraft.
 I like it 
  September 14, 2012
Great work!
 
By Gabor Pauler
Add to my favorite builders

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LEGO models my own creation MOCpages toys shop Cockpit controls with ejector seats (working)Technic


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