R/C 'Los Angeles' Article & Plans
December 1968 American Aircraft Modeler
Airplanes and Rockets visitor wrote requesting that I post this
article on the R/C Los Angeles airship, so here it is.
There have been a few articles in the last year or so reporting
on radio-controlled blimps (airships, dirigibles, etc.). The advent
of super-light radio gear, powerful little brushless motors, and
high energy density batteries has made them practical in almost
any scale. This "Los Angeles" model is 53" long and 11½" in diameter,
and will lift 8-10 ounces of gear. In 1968, when this article was
published, there was no lightweight film covering material that
was both strong enough and gas-tight enough to do the job, so thin
silk and butyrate dope were used. Modern covering and equipment
should let this baby fly to the moon!
R/C 'Los Angeles'
Patterned after a famous airship, this model can be made smaller
or larger. Use data given here to build your own dirigible.
By John A. Wick
Perhaps a dirigible is your bag? Helium supports
it, electric motor pushes it, and rudder-only by escapement steers
ON October 15, 1924, as a war reparation
payment, the German Zeppelin Airship Works delivered to the United
States the ZR-3, later re-christened the "Los Angeles." This 658-foot
dirigible had just completed a 5000-mile flight from Friederickslafen
to Lakehurst, N. J., and this was just the beginning. The ship logged
a total of 4,320 hours in 331 flights, before being decommissioned
at Lakehurst in 1932 and scrapped seven years later.
jet aircraft are so commonplace that most people won't spare an
upward glance. On the other hand, it would be most interesting to
observe public reaction to a silver cigar-shaped object almost three
city blocks long, flying, or should I say sailing, overhead. It
is indeed sad to note the passing into another time of the giant
airships, but the long record of tragedies associated with their
existence, doomed them to extinction. The final curtain of dirigible
development fell when the Hindenburg unexplainably burst into flames
and was completely destroyed with a loss of 36 lives while attempting
a mooring at Lakehurst in 1937.
Lattice-work of stringers makes it a true airship. Structure
is quite similar to the real Los Angeles. Light and durable.
Regarding the model, I had always kept the thought of constructing
a working model of a dirigible in my model building itinerary. Finally
construction began with the success or failure reported herein.
It seemed logical to me that if an aluminum structure was used on
the original airship, a careful substitution of balsa would be both
strong and light enough to maintain a lighter-than-air condition.
The ship is built on a 1/8" sq. crutch in the half-shell
fashion. The most difficult part of the construction is in the aligning
of the first four stringers. Once these are glued in, the structure
will take on a little strength. After gluing in half of the bulkheads,
and while still on the board, add three temporary 1/16" sq. braces
between each of the bulkheads. After adding bulkheads to the other
side and installing these temporary braces, the structure may be
suspended from the rafter and the stringers may be installed, to
each side. The structure will be strong enough to work on normally.
Many less experienced modelers have added stringers to a half-shell
while still on the board, resulting in a bowed framework. This would
be most noticeable on the dirigible because of the larger than usual
size of the ship as compared to the smaller than usual size of material
used in the construction.
The gondola is constructed on
the ship before it is covered with silk to insure a good fit. Two
pipes of 1/116" aluminum are epoxied in; one is a filler, the other
a vent. The main fill tube is located in the gondola, which is made
oversize to contain an Otarion receiver and escapement. The small
electric motor in the rear pod drives a pusher propeller which just
barely moves the craft. The initial filling of the ship with helium
resulted in a collision with a sharp rafter projection, and down
it came. After patching and refilling, a successful flight was made
across the living room. In about five minutes the ship slowly settled
to the floor. It was clearly evident that the dope covered silk
would not hold helium. After some heavy concentration, we thought
perhaps two coats of hot-fuel proofer might work.
rendered the envelope leak-proof and many short flights were made.
By the addition of varying amounts of clay ballast, neutral trim
could be maintained and with the power on a slight climb was evident.
The original model is 56" long and weighs in at 11 ounces. It will
lift approximately eight to ten ounces of radio gear, depending
on the existing barometric pressure. A larger craft of six to seven
feet length is planned for the future, utilizing three-channel R/C
gear. These model airships are designed for in door flying exclusively
because, like their big brothers, they would be subject to the slightest
breeze and, if one did overfill or hook a thermal, it would probably
result in the longest model chase in history.
flyer suggested that it would make an excellent indoor model retriever.
With more experimentation on the project, he may be quite correct.
Dirigible specs: Overall length is 53";
maximum diameter 11-1/2". Airframe weighed 13 oz. less the R/C gear.
Entire hull is sealed in order to allow maximum room for helium.
Covering is silk with six coats of dope and fuel-proofer to seal
against loss of helium (this gas will leak rubber membrane).
Framework is built upon a 1/8" sq. crutch formed of the backbone
and a keel. Each bulkhead is one-half of a circle and of 1/16" sheet
balsa. Crosspieces under each bulkhead are also 1/8" sq. Cross-braces
radiating from the center of the ship and outward to the bulkheads
are 1/16" sq. Bulkheads are not notched for them.
On each half 25, 1/16" sq. stringers were used about eight degrees
apart - could probably change this to 10 degrees apart to simplify
matters. After erection of the bulkheads on the crutch, remaining
halves of each bulkhead were cemented in place. Lastly, the stringers
were added, this being done off the workbench and in the hands,
so to speak. Two 1/16"-dia. aluminum tubes are used for the fill
and vent. Both fill and vent should be on bottom of dirigible -
the top; rear location for the vent is wrong. Vent must be on bottom
so heavier air can escape and be displaced by the lighter helium.
cabin is a very light framework fitted to the body first, but not
cemented on until the body has been covered. It had windows in it
but they were left without plastic covering. Escapement was connected
to rudder with monofilament lines (externally).
Micro-Mo motor was the power driving a 2½"-dia. plastic prop from
a plastic model kit. Battery power was taken from the very smallest
of pen-cell-type dry batteries. Batteries are connected to motor
with small, enameled copper wires (externally). Motor is mounted
in small, hollowed-out balsa pod. Other dummy motors-not shown in
pencil drawings - were made the same way.
all of 1/16" sheet, hinging of 1/32" wire and 1/16" aluminum tube.
Tube must go through fuselage vertically to eliminate leakage. Short
alternating sections of tubing may be silked to 1/16" sheet. Fin
braces radiate (there are eight of them) from four equidistant points
around the fuselage. You can label these points "X." They branch
out and go to opposite side of each fin at points "Y".
C.G. position. Just add clay until dirigible balances in a slightly
nose-down condition (under power the nose will come and a shallow
climb results). Addition of clay also allows the modeler to regulate
the amount of lift useable. You don't want too much. Helium is retained
for about 20-30 minutes. Payload is about 8-10 oz. depending upon
<click for larger
The AMA Plans Service offers a full-size
version of many of the plans show here at a very reasonable cost. They will scale the plans any size for you. It is always
best to buy printed plans because my scanner versions often have distortions that can cause parts to fit poorly. Purchasing
plans also help to support the operation of the Academy of Model
Aeronautics - the #1 advocate for model aviation throughout the world. If the AMA no longer has this plan on file, I
will be glad to send you my higher resolution version.
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Posted September 27, 2011