- This file may be freely distributed,
so long as the authorship and copyright notice remain intact.
- We all know about B-2's and F-117's,
and could see how they might be described as "disk-shaped" if
viewed from the appropriate angle. Here's some other information about
some similar aircraft from the past. They are presented here merely to
show that disk-shaped flying craft are not only possible, but have been
- XB-35 - In response to the possibility
of Britain falling in the early stages of WWII, the US Army Air Force began
taking designs for extremely long-ranged, heavy-bomb-load aircraft that
could fly from North America to Germany and back, carrying 10,000 pounds
of bombs. Northrop proposed the XB-35. The XB-35 had 4 engines, each driving
two counterrotating pusher propellers along the same shaft (!). Pictures
of the XB-35 look like each shaft has a six-bladed propeller, but its actually
two three-bladed propellers -- for a total of 8 propellers.
- Jack Northrop had been experimenting
with flying-wing designs since the early 1920's. In Germany, the Horton
brothers (see below) were working on a flying wing as well -- the final
designs look surprisingly like the XB-35 (though it had only two propellers).
- Northrop's first prototype was the N-1M
(nicknamed "the Jeep"), which was tested in the Roseman Dry Lake
in the Mohave Desert from July 1940-early 1942. It had two pusher propellers,
and space for one pilot. Wingspan was 38 feet, and the plane weighed 4,000
pounds. First "public" flight made the newsreels. The wings were
altered significantly as testing went on; for instance the "drooping
wingtips" were discarded early on. The (only) N-1M stills exists,
and has been restored, it is now sitting in a Smithsonian storage hangar,
painted its original brilliant yellow.
- Northrop was contracted by the US Army
Air Force Materiel Division to build one XB-35 (wingspan 172'). The N-9M
was the first product from the contract, a 1/3 scale (working, though wood-structured,
not metal) model with two engines with a 60' wingspan as a testbed/trainer.
It first flew successfully on Dec. 27, 1942. Three other N-9M's were built,
and the N-9M test program was completed in Oct. 1944. [The last surviving
N-9M is being painstakingly rebuilt by the "Planes of Fame" Museum,
in Chino, CA] One of the N-9M's crashed during testing.
- On June 25th 1946, the XB-35 was at last
ready to fly (after a number of difficulties with the propellers) at Hawthorne
Field, CA -- the Northrop company field. The '35 was now in competetion
with what became the Consolodated B-36 as the postwar strategic bomber
(interestingly, both planes were pushers.) Its first flight was from Hawthorne
to Muroc Dry Lake (later named Edwards AFB) for additional testing.
- Attempts to make the propeller system
less complex were generally unsuccessful. Northrop decided to replace the
props with 8 jet engines, and continue work on the plane, renamed the YB-49.
Only 2 XB-35's were ever completed, the second one first flying on June
26, 1947. The Martin Corporation worked on the YB-35 (same basic plane,
just built at Martin), and the only YB-35 first flew on May 15, 1948.
- YB-49 - The power problems of the XB-35
completely disappeared with the jet engines, but unfortunately they reduced
the range of the plane such that it could not be thought of as a strategic
bomber (mid-air refueling not then being feasible).
- The second YB-49 produced was the first
to fly, flown by Maj. Robert Cardinas, the US Army Air Force test pilot
assigned to the Northrop program (i.e. Northrop retained control, but had
military test pilots mixed in with their own.) On April 26th 1948, the
YB-49 flew 4,000 miles with a 10,000 pound payload, on circuitous route
that took it as far east as Phoenix, and as far north as San Francisco.
- In June, 1948 a YB-49 on a routine test
flight crashed (Capt. Glen Edwards, for whom Edwards AFB is named, died
in this crash, along with four others); specific cause of the crash was
never determined; structural failure was the most likely reason.
- The military had expressed an interest
in a reconaissance version (with two extra jets) of the YB-49, called the
YRB-49, and placed an order for 30. In January 1949, though, this order
- In Feb. 1949 the remaining YB-49 flew
from (now) Edwards AFB to Andrews AFB in record time (just over 4 hours
- the record was broken the next day by the XB-47, its medium-bomber compeditor,
which flew almost 100mph faster). The famous YB-49-over-the-Capitol photos
are from this flight. President Truman toured the plane's interior on the
ground, and then '49 headed back to Edwards. During the flight, 6 of the
8 engines failed due to an oil failure which has a slightly mysterious
history (apparently the oil reservoir had not been filled properly before
the flight -- there are hints of sabotage). The YB-49 made an emergency
landing at Winslow AZ. Later on in 1949 the last flying YB-49 was destroyed
during high-speed taxi tests, when the undercarriage collapsed.
- In November 1949, the Air Force (the
US Army Air Force became the US Air Force on July 26, 1947 -- it changed
from the US Army Air Corps to the US Army Air Force on June 29, 1941) cancelled
the last part of the YB-49 contract, that of converting the remaining partially-completed
XB-35's to jet power. The last 11 XB-35 hulls (in varying states of completeness)
were rolled out onto the flight ramp outside of the factory, lined up,
photographed (a very impressive aerial photograph of them lined up survives)
and broken up for scrap. Northrop employees made a last-ditch request to
finish the planes in their spare time, which Jack Northrop had to turn
down, for fear of jeopardizing further military contracts (political shenanigans
for government contracts were just as silly back then as they are now,
and Northrop was concerned that Stuart Symington, secretary of the Air
Force, would look unkindly on Northrop in general if the planes were not
destroyed -- Symington was very specific that the YB-49 program not continue.
Northrop partisans say that Symington wanted to force Northrop to merge
with Convair, for reasons of his own, and was hoping to damage Northrop
enough to force the merger. Others say that the expected costs of the YB-49
were sufficiently higher that the XB-57 to warrant the choice of the latter.)
- (Other WWII-flying-wing ideas from Jack
Northrop included the turbojet-powered XP-79 "Flying Ram", a
rocket-powered interceptor that was designed to literally slice the tail
off of enemy aircraft with its heavily-reinforced wing to knock them down.
The XP-79 actually flew (once -- it crashed), along with at least one similar
prototype, the (rocket powered) MX-324, which first flew (powered) on July
5, 1944. Another was the JB-1, an unmanned rocket-assisted, turbojet-propelled
missle, and the XP-56, another pusher-flying-wing; this time a fighter,
with two counter-rotating propellers along the same shaft, which also made
several test flights, in 1943 and 1944 one of the two XP-56's crashed in
a landing, the other wound up at the National Air and Space Museum.)
- Jack Northrop resigned from the company
he had built after the YB-49 was cancelled, and left the aircraft industry
entirely. In the mid-1970's, NASA sent him a letter that they were re-examining
the flying wing idea (also, the YB-49's small radar signature was being
taken more seriously by then.) In April 1980, he (suffering now from Parkinson's
disease) was given a security clearance, taken to Northrop, and shown a
model of the B-2. Makes a nice ending to the story, eh? The B-2 has exactly
the same wingspan as the YB-49 (172').
- (An interesting sidelight: in the late
1940's Northrop had also made a slick promotional-film campaign to drum
up support for the flying wing; this included a film describing a proposed
80 passenger flying-wing commercial jet.)
- Also, here are some other (lesser-known)
planes that appear "disk-shaped" when viewed from one angle or
another. (Note that both these aircraft did *not* become operational, for
- The Horten Brothers' Wings - in the 1930's
and 1940's in Germany, the Horten Brothers, Walter and Reimar, built a
succession of flying wing designs which were quite advanced, and on the
cutting edge for their day. Their "Ho" series is as follows:
- Ho I - 1931 - a flying-wing sailplane.
- Ho II - 1934 - initially a glider, it
fitted with a pusher propeller in 1935. Looked very like Northrop's flying
- Ho III - 1938 - a metal-frame glider,
later fitted with a folding-blade (folded while gliding) propeller for
- Ho IV - 1941 - a high-aspect-ratio glider
(looking very like a modern sailplane, but without a long tail or nose).
- Ho V - 1937-42 - first Horten plane designed
to be powered, built partially from plastics, and powered by two pusher
- Ho VI "flying parabola" - an
extremely-high-aspect-ratio test- only glider. (After the war, the Ho VI
was shipped to Northrop for analysis.)
- Ho VII - 1945 - considered the most flyable
of the powered Ho series by the Horten Brothers, it was built as a flying-wing
trainer. (Only one was built and tested, and 18 more were ordered, but
the war ended before more than one additional Ho VII could be even partially
- Ho VIII - 1945 - a 158-food wingspan,
6-engine plane built as a transport. Never built. However, this design
was "reborn" in the 1950's when Reimar Horten built a flying-wing
plane for Argentina's Institute Aerotecnico, which flew on December 9,
1960 -- the project was shelved thereafter due to technical problems.
- Ho IX - 1944 - the first combat-intended
Horten design, it was jet powered (Junkers Jumo 004B's), with metal frame
and plywood exterior (due to wartime shortages). First flew in January
1945, but never in combat. When the Allies overran the factory, the almost-completed
Ho IX V3 (third in the series - this plane was also known as the "Gotha
Go 229") was shipped back to the Air and Space Museum.
- [Interestingly, the Horten brothers were
helped in their bid for German government support when Northrop patents
for the N-1M appeared in US Patent Office's "Official Gazette"
on May 13, 1941, and then in the International Aeronautical journal "Interavia"
on November 18, 1941.]
- [Of course, one other "Flying-Wing-type"
plane existed in the German Luftwaffe - Alexander Lippisch's-inspired Me-163
rocket-powered interceptor, and its intended successor, the Messerschmitt
P.1111, a turbojet-powered fighter. At the end of the war, Lippisch was
engaged in supersonic-fighter research, models of his "P12" were
shipped back to the US for analysis.
- The "Zimmer Skimmer" (aka "The
Flying Pancake") - in an attempt to develop a high-speed interceptor
(fast enough to overtake diving enemy planes) to deal with Japanese kamikaze
attacks, the Navy asked for bids for such an aircraft in early 1944. (The
Chance-Vought F4U Corsair - and the Grummann F4F and F6F - eventually filled
this bill more or less, but were hard to land on carriers, for weight and
pilot-visibility reasons). Minimum speed desired was 450mph, then-available
planes would do only about 400mph.
- Charles Zimmerman, a research engineer
for NACA, had come up with a disk-shaped, two-propeller aircraft idea before
the war, which promised to be fast, and have short-take-off-and-landing
ability (which included the ability to hover), which would be useful on
aircraft carriers. (Imagine an oblong disk, with a canopy on top near the
front, twin rudders and two small aerolons in the rear, and twin booms
extending forward from the left and right sides of the disk with a huge
counterrotating propeller on each. The undercarriage was a spindly-looking
tricycle arrangement that had the "Skimmer" taxying at about
a 40 degree angle. The fuselage was the "wing", but was much
thinner and wider than later "lifting body" experiments. Hovering
was accomplished by going nose-verticle and, well, just hanging there -
such was the power of the propellers. Wingspan approximately 30-40 feet
[by my eye].)
- The V173 (the first prototype version)
was built by Chance-Vought. Boon T. Guiten was its first test pilot. Its
first flight (November 23, 1942) lasted only 13 minutes, but was entirely
successful, and testing continued. One of the later-on test pilots was
Charles Lindberg, who was an enthusiastic supporter. In July 1944, the
Navy ordered two more "Skimmers" built for further testing, each
equipped with significantly more powerful engines (1350hp Pratt and Whitneys
-- the V173 was judged underpowered, since its top speed was not up-to-spec).
The two new planes were built from "metalite", a composite material
made from sandwiching layers of aluminum and balsa wood. These planes were
- The F5U's were actually overpowered,
and had a clutched gearing system to vary propeller speed in flight. In
addition, a geared propeller-synchronizer was also installed. The first
F5U was ready for flight in August, 1945 (but was delayed by a lengthy
redesign of the propellers). By 1948, an F5U was finally ready to fly,
but technology had passed the plane by (jets were already doing 600mph).
The F5U taxi'd up and down the runway a couple of times, but never flew.
Total pricetag on the project was about $9M. Both 5FUs were scrapped. (The
F5U's were intended to be sent to Edwards AFB for testing -- shipped via
the Panama Canal; apparently the skimmer's unusual shape would have made
ground transport difficult.) [In the mid-1930's the Arup S1, S2, S3 and
S4 - looking very like what became the Zimmer Skimmer, but with a single
centerline "puller" propeller - were flown as flying billboards
and test aircraft.]
- The Avro (Canada) "Avrocar"
was an outright flying saucer. It used three Continental turbojets, turning
a central impeller ("turbo rotor") to keep it airborne with downward
thrust, with a vane/shutter system to propell the craft in pretty much
any direction by venting thrust in any direction desired. It was built
to hold two human crewmen in separate cockpits on either side, facing front
- total width of the Avrocar was 18 feet, with tricycle landing pads or
wheels for undercarriage. It was first proposed in the early 1950's by
the Avro company to the Canadian government.
- The maximum expected airspeed was originally
about 700mph. As Avro worked on the design, expected airspeed dropped to
300mph. By the mid-50's, a very-secret project (unknown to even most Avro
employees) was in full swing to build the Avrocar. The blades of the Avrocar
turbo-rotor were hollow with internal re-enforcing, and brazed to cement
the parts. The first turbo-rotor was tested for 150 hours without mishap.
- By 1955, the costs of the project had
escalated beyond the resources of the Canadian government. The project
after that was underwritten by the US DoD (the USAF and Army were both
interested.) The Avrocar first flew with a pilot on Dec. 5, 1959 (prior
to that, it was tested unmanned). Two were built - one Avrocar was tested
out at the Ames research center in California, the other remained with
Avro for testing. Although the aircraft did fly, its ability to rise and
top speed was extremely disappointing, mostly due to thrust dissipation
in the impeller. The Avrocar was able to clear (small) obstacles without
difficulty, but maximum altitude was never more than about 6 feet! The
project was quietly closed down.
- Both Avrocars are still intact, and survive
in US museums (not sure which, though).
- ... curiously, the Avrocar's technology
was within a hair's breadth of being successful. Using almost exactly the
same propulsion setup, the British developed hovercraft (the first being
the British SRN-1) in the early 1960's -- basically an Avrocar propulsion
system with a rubber skirt, which greatly improved the use of downward
- ... in recent years, a one-person "homebrew"
version of an Avrocar has appeared (alas, I cannot remember the fellow
who built it's name, but he has built a lot of neat flying vehicles, and
I've seen film of the avrocar-like vehicle flying).
- Edmund Doak also was contracted by the
USAF to develop disk-shaped airfoil aircraft in the 1950's and 1960's.
His last and most promising, the Doak-16, was canceled by the USAF.
- [Sources: Documentary "The Wing
Will Fly", a 'Wings' documentary on "Strange Planes", and
"Winged Wonders", by E.T. Wooldridge, published by the National
Air and Space Museum, 1983, "In Search Of" episode "UFO