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|1. Credits & Specs
The next generation in R/C steam tank design. This is my
variation on Crabfu's Steam
Lobster tank. Fire, water, steam, motion!
After finishing my original tractor tank, I longed for one
with a working turret & more power. Thus my R/C live
steam powered tank with turret & gun! The build is a
little complicated. See build details in my Steam
Turret Tank Instructable!
1/16 King Tiger (clutch drive)
3.5" Horizontal Steam Boiler, two Regner Piccolo Steam Engines
mix (camping fuel)
Sheet Metal & Brass Fittings
DX6, one Futaba S3010 servos, four Spektrum S75 miniservos
Runtime: 15-20 minutes
Weight: 13 lbs
R/C steam engine
powered turret tank
The R/C steam turret tank uses 100% steam power for propulsion.
Batteries only power the R/C, lights & gun effects
Tamiya 1/16 King
|As before I used an old
1/16 scale King Tiger (KT)
eBay. There the similarities end. The original
gearbox slipclutch was removed, and gearbox frame shortened to make
room for the new boiler, engines & fuel tank.
Motive power is generated by a MaccSteam 3.5" Horizontal Steam Boiler
two Regner Piccolo Marine steam engines. Engine output is
routed around the fuel tank with some reduction
gears to increase torque.
The reduction gearing is 15t/38t on the engines, and 19t/56t on the
gearbox. Mounting brackets for the gear axles are made from
13 hole Meccano strips. The ends are bent to fit
within the chassis as shown below.
The engine mount holds the two engines & attaches to
A 4" x 6" piece of 0.064" (1/16") aluminum is placed
over the suspension brackets, and marked to locate the tabs. 1" slots
are cut and the tabs bent as shown.
The tabs are ~1/2" deep, and carefully fitted between
the suspension springs. Adjust/trim as necessary.
A center punch is used to mark each tab, and drill
through the bracket and chassis. Sheet metal screws attach the bracket
Engine Mount Sketch
| A triangle of aluminum
redirects whistle servo motion. The corner is anchored to the chassis.
When the servo tugs horizontally, the other corner moves vertically.
A piece of brass chain connects the triangle and the
whistle, and 1/16" brass rod to the servo control rod, with s-curves
bent on both ends.
To mount to the chassis, I used a 3/16" standoff, a
couple washers & sleeve for tightening the nut against while
letting the bracket turn freely.
The servo mount bracket holds the engine servos, whistle
servo, R/C receiveR/Controller, and battery pack. It's made from
0.032" aluminum and has stiffening flanges bent on all four sides. A
pocket for the receiver is formed with a couple more bends.
Servos are installed & holes marked & drilled
for mounting holes. The receiver & controller slip into the
pocket. Pieces of cut-open 3/8" shrink tube & electrical tape
insulate the electronics where necessary. The battery sits on the front
of the bracket held by double-side sticky tape.
Servo Bracket Sketch
Steam from the boiler needs to reach the engines,
whistle & displacement lubricator.
I fabricated a manifold
from brass, and started with a 5/8" square brass rod. I cut a
3/8" thick piece & drilled #1 holes in two sides and a
face halfway through so they joined up inside.
The manifold tube is made from 5/16" solid brass rod,
drilled 5/32" through the center. One end is #1 drilled
& 1/4-40tpi tapped for the lubricator. Two 0.1" holes
are drilled for the engine feed pipes & 6-32tpi tapped. Two
brass standoffs are dirilled through & trimmed to just grab the
tube threads, then everything was silver soldered together.
For the front of the body,
first I made a u-shaped piece from a 4"x7" 6061 aluminum sheet.
covers the fuel tank & supports the turret. It has a 2-3/4"
diameter hole (based on a Meccano ring gear) for clearing the fuel tank
valve, turret gears, wiring to the turret, etc... The 6061 aluminum
coupled with the steel ring gear makes it strong enough.
Designing the remaining front panels took quite a while to flesh
out. Lots of prototyping with paper, cardboard & tape. ie: cutting,
bending, taping a little back on, repeat, etc...
The sketch shows my final
design. Once the side panel shape was final, I continued the curve onto
the front-most lobster shell.
2-56 x 1/2" brass hex
bolts, washers & nuts
hold everything together except the front apron. It's held with #2 x
3/16" brass hex lag screws for battery access.
|The track fenders are made
from 3" x 18" strips of 0.032" 6061
aluminum. I used the stronger aluminum here since fenders are exposed
I used a bending brake to make a 3/8" flange on the inner
edge & 5/8" on the outer. The chassis tracks are 2" wide, so that
determined the center-width.
Removing a couple inches of flange from the front/rear
shaping the fender. I sketched a smooth curve which ended on the outer
flange, rough cut with metal shears, and filed the edges smooth.
Holes were traced from the Mahogany strips made when
assembling the body & 3/32" drilled. I kept the Mahogany strips in
the final build to add extra width & enhance the look. Loctite
secures the 2-56 nuts during final assembly.
The hand rails are made from 15mm flat stanchions and 1/16" brass rod. The
stanchions are placed every 2 to 2-1/4" along the fender, bending in
before the headlights. Drill mounting holes, insert stanchion mounting
tab, and twist with pliers to affix.
Holes for head/tail lights were marked & drilled.
headlights are STE162 Gimbaled & Fixed Clear Searchlights. The tail
lights STE152 Bullet-Style Navigation lights.
A 3-1/4" diameter needle roller thrust bearing from eBay sits on the
ring gear supporting the turret.
I fabricated an aluminum ring base with tabs for
turret body. The outer diameter was determined by a 4"x10" sheet of
K&S aluminum. The inner diameter matches the thrust bearing.
Upward bent tabs on the outer edge attach to the turret
Downward bent tabs on the inner edge align the thrust bearing. Straight
tabs on the inner edge are for idler gears & servo (see sketches).
The gears keep the turret overall centered within the ring gear.
I reused a servo from the original tank here. The servo gear
is cut from a 25T Meccano gear. It's 1/8" thick with a thin hub. A #1
hole was drilled about halfway through to fit the servo spline gear.
Turret Base Sketch
Turret Servo Gear
started simple (a cylinder), but I didn’t like the look so added the
curved gun port bump-out & rear box structures.
The front bump-out is three
pieces. Two sides & a
front plate. Either freehand or use a drafting
to sketch the curves onto some 0.032" aluminum. 2-56 brass
bolts hold it all together.
The turret top is made from 0.064” (1/16") aluminum
with Mahogany strips glued on. To attach the top to the turret body,
several L brackets from scrap aluminum are glued on.
Finishing touches involved bending some 1/8" brass
to hide the aluminum, and adding railings. I eyeballed positions for
15mm stanchions (same as fenders), drilled holes, and fitted/soldered
the 1/16th brass rod railings. After painting, the turret sides are
adorned with lion crests taken from some brass buttons
The gun mount
is a 4-1/8" x 5/8" aluminum rectangle folded
into a narrow box, with a tab for the gun elevation servo. It's folded
& the joint JB-Welded. A 5/32" hole drilled through is for the gun
pivot axle. When bending its important to preserve the 1/2" internal
gap otherwise the gun barrel doesn't fit.
The gun barrel is formed from two pieces of aluminum tube. A
1/2" tube and a polished smaller 3/8" tube that slides smoothly within.
A solenoid sits within the larger tube, and pulls the smaller
one inwards to simulate cannon fire. Combined with an ultra-bright
yellow LED, WTV020-SD
sound module & Railmaster DHB8
8-ohm 2W miniature speaker
(w/enclosure), the effect is pretty good!
The solenoid proved annoying since it dropped the battery
voltage enough to brownout/reset/disconnect the R/C receiver &
controller logic. Some 1F capacitors & a current mirror for
charging them fixed that problem.
Gun Port Sketch
Gun Barrel Sketch
Gun Barrel Assembly
R/C steam turret tank
|5. Materials List
- Other Supplies
Strips (1/8" x 1/4" x 24")
Fiber Paper (1/16")
- High Temperature Engine Enamel Paint
- Oak Trim Panel (3.5" x 24" x 1/4") - Boiler heat
- Aluminum Sheets - 0.032" (1/32") and 0.064" (1/16")
- Brass Square (5/8") & Round rod (1/16", 5/16" &
- Brass 1-1/4" Round tube
- Brass 1/8" U-Channel
- Acetal Plastic Rod (3/8" diameter)
- Zinc-Core Candle Wick (52-32-18)
- Various screws/washers/nuts/etc...
- Loctite Thread Locker, Cyanoacrylate glue, JB-Weld