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All the photographs and notations for this feature
were kindly sent in by Richard E. Fulwiler of Portland,
Oregon.
Richard grew up near the Van Nuys Airport, home of On Mark,
and had access to their facility until Marksman C #7 and 8 were started, coinciding with the B26K modifications. He was present
on the return of the prototype of the YB26K (#35634) from its first flight when he was 16.
Richard has been good enough to share with us all, an incredible collection
of personal photos of his time at Van Nuys and we are truly honoured to have a true incite as to how it was back in those
early days of aviation development.
Thank you Richard
On Mark Engineering, an introduction
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In 1962 On Mark undertook the conversion of a Boeing Stratocruiser on behalf of Aero Spacelines, Inc.
The aircraft would become known as the B-377PG Pregnant Guppy. The first flight occurred on September 19, 1962 at Van
Nuys Airport.
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On Mark Engineering Company completed conversion of 40 Douglas A-26 Invaders to On Mark B-26K Counter
Invaders for the CIA and the USAF during 1963 and 1964.
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In 1965 On Mark undertook the conversion of a Boeing C-97J on behalf of Aero Spacelines, Inc. The
aircraft would become known as the B-377SG Super Guppy. The first flight occurred on August 31, 1965 at Van Nuys Airport.
Best-known of the civilian Invader conversions were those done
by the On Mark Engineering Company.
Located in the southeast corner of the former WWII Army Air Force
Base Unit facilities, On Mark Engineering Company was formed in 1954 and specialized in the modification, repair and overhaul
of the Douglas A-26 Invader aircraft for the civilian executive transport business.
Among these were the pressurized Marksman A, B, and C. The Marksman
A had 2100 hp R-2800-83AM3 engines, the Marksman B had 2100 hp R-2800-83AM4A engines and wingtip
fuel tanks, whereas the Marksman C had 2500 hp R-2800-CB-16/17s and internal auxiliary fuel tanks.
On Mark provided the additional room for passengers in the cabin
of the aircraft by removing the rear wing spar and substituting a circumferential ring bulkhead to which the wings were mounted
in the same place as with the carry through spar. The forward wing spar was not changed because of the magnitude of the re-engineering
that would have been required, which meant that crew members were left with the inconvenience of mounting the flight deck
through a crawlway along the right side of the cabin beneath the spar.
All of the Marksmen had a redesigned and pressurized fuselage
with a new flight deck, a DC-7-type heated windshield that was more resistant to bird strikes than the original B-26 windscreen,
and improved brakes, deicing, soundproofing, radio/navigation and other systems. They could carry from 6 to 12 passengers.
The base price of the Marksman was $257,430.
There was also an unpressurized version of the Marksman C known
as the Marketeer that lacked the solid roof and the DC-6 cockpit glazing of the Marksman.
On Mark also undertook conversion work of a Boeing 377 Stratocruiser into
the prototype Pregnant Guppy for Aero Spacelines.
Richard E. Fulwiler wrote regarding the images below:
Martin, glad
you find these useful! Definitely a case of being in the right place at the right time. No one until you has appreciated so
greatly these images. The picture below is the man who made it possible for me to get these shots, William Boone, Sales Manager
of On Mark. After the contract was signed for the 40 B-26Ks, in 1963, he could no longer allow me access, but what fun it
was to have On Mark as a big boy playground! This was also the time when Marksman #7 (C model), 44-34415, C/N 27694, N900V
(then N46358 "The Blue Goose") and Marksman
#8 (C model), 44-35698, C/N28977, N800V (then N67623) were contracted
by our government for special operations. As I understand, they were Marksman C's built to B-26K specifications. My research
has found that these went to Thailand and wound up eventually at Norton AFB, in San Bernadino, CA, where they were scrapped.
(Google Maps will give you a good satellite view of Norton).
All my favorite haunts at Van Nuys are long gone, but the memories
are still fresh! The On Mark site is now an industrial park and the Ted Smith Aircraft plant, where I worked building Aerostars
in 1969, was torn down a few years ago. Glad there are still some of us around that appreciate the old birds and get excited
by the sounds of anything powered by Pratt & Whitney R-2800's, Rolls Royce Merlin's and Lycoming TIO-540's.
I don't know if you can use a photo of someone without their
permission, but Bill had given me his permission to take this photo in front of the YB-26K
William Boone, Sales Manager
and the man who motivated the successful sales of
On Mark aircraft
The On Mark Marksman
The above two shots - (right front) Cornell University
(becomes CALSPAN) N9146H, a B-26B-45-DL used for aeronautical research.
On the left is Marketeer N237Y in the final stages of prep prior
to delivery to Standard Oil Co.
The above shot - On the left, Marketeer "Initiator V" (believe
the registration number at that time to be N706ME).
Aircraft was being made airworthy after right main gear collapsed,
was disassembled and trucked to On Mark for repair.
Note the vertical tail of N237Y (directly behind the Initiator
V)
The above shot - Hamilton Standard, fully
reversible, broad chord propeller as installed on all Marksmans and some Marketeers. Used in conjunction with Pratt and Whitney
2500 HP R-2800 CB17 engines.
The two shots above - Left engine of the Initiator
V, showing the broad chord propeller hub and afterbody assembly.
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Above, I Believe the aircraft behind
N5530V is L. B. Maytag's N320 as a Marketeer prior to Marksman conversion.
The five shots above - Marketeer N5530V on
north ramp at On Mark (looking NNW). Note the original Van Nuys control tower and the C-97 from the 146TH Air Transport Wing.
YB-26K - Prototype for the B-26K
On Mark B-26K Counter Invaders (40 aircraft produced)
Note: The Pentagon paid On Mark $400,000 each
to rebuild 40 A-26s, double what the planes cost when they were built initially during World War II by Douglas Aircraft Co.
The following photos were taken at On Mark Engineering Co.,
Van Nuys Airport, Van Nuys, CA 1962
The above shot - YB-26K underwing pylon install
prior to first flight.
On Mark / Aero Spacelines B-377PG Pregnant Guppy (1 aircraft produced)
On Mark / Aero Spacelines B-377SG Super Guppy (1 aircraft produced)
In 1960, US airlines were disposing of their obsolete piston-engined
Boeing 377 Stratocruisers in favour of the newer jet-engined airliners. NASA was finding that barge transport of their increasingly
large space program components from manufacturers on the West Coast to test and launch sites on the East Coast was slow and
expensive. Aircraft broker Leo Mansdorf was stockpiling surplus Stratocruisers at Van Nuys prior to resale, and ex-USAF pilot
John M. Conroy realized the potential of these aircraft to transport the large but relatively light rocket components.
Conroy presented his plans for an extensively modified Stratocruiser
to NASA, where an official commented that the bloated aircraft resembled a pregnant guppy. Although NASA was lukewarm on the concept, Conroy mortgaged his house and founded
Aero Spacelines International in order to build and operate the concept aircraft.
Conversion work was undertaken by On Mark Engineering. The Pregnant
Guppy (registered N1024V) was built from an ex-Pan Am airframe with a five-meter section from an ex-BOAC aircraft (G-AKGJ)
added immediately behind the wing. The wing, engines, tail, nose and cockpit were unchanged, but a new upper fuselage of six
meters diameter was added, giving the aircraft a "triple-bubble" appearance in front view. The entire rear section (including
tail surfaces) was detachable to allow cargo to be loaded directly into the fuselage.
The aircraft first flew on September 19, 1962. When Van Nuys
traffic control realised that Conroy intended to take off, they alerted police and fire departments to be on alert. However
the huge aircraft performed flawlessly, the only difference in handling being a slight decrease in speed caused by extra drag
of the larger fuselage.
"The
first time the Pregnant Guppy (its peculiar shape gave it the name) took off from California’s Mojave Airport under
its maximum weight of 141,000 pounds, in the spring of 1963, it did manage to get aloft, but just barely. After the usual
long, lumbering ground run, the landing gear was retracted, but the ship could climb no faster than the hilly ground was rising
in front of it. The air speed seemed locked at 128 knots. An awed and expectant silence prevailed in the cockpit, even as
the engines and propellers churned away at their noisiest level.
The town of Boron loomed dead ahead. It
looked as if the Guppy’s crew would clean it out if they didn’t turn, but a turn might sink them back into the
ground. The flight engineer saw that the right inboard engine was giving them trouble. He told the pilot, “Number three
is overheating. Can I pull it back?”
“Don’t touch it.”
“But it will burn up!”
“Let it burn.”
To this day some crew members swear that
the burning of fuel, with its consequent lightening of the plane, was the only reason the Guppy finally managed to climb.
They say a string of skeletons from jackrabbits that died of pure fright runs from Mojave to Boron. After that flight the
engineers and pilots agreed to decrease the plane’s maximum weight by 8,000 pounds before anyone took it up again."
The above two shots -
After the initial flight tests were successfully completed, the
Aero Spacelines' "Pregnant Guppy" was returned to On Mark to install the fuselage separation joint.
Note the "wool tufts" on the rear fuselage to show the airflow
patterns at the end of the bulbous shape of the expanded fuselage in some of the photos.
Note the wool tufts to show airflow patterns on below shot. There
was great concern that the airflow would be disrupted by the huge flared fuselage, but it was not the case.
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