Date: Tue Apr 26 1994 23:22:00 To: All Subj: Flying Wing Sampler, 1/4 UFO - Courtesy of: J
Date: Tue Apr 26 1994 23:22:00
From: John Powell
Subj: Flying Wing Sampler, 1/4
Courtesy of: John Stepkowski
By Charles McGrew
Copyright 1992 by Charles McGrew
This file may be freely distributed, so long as the authorship and
copyright notice remain intact.
Known "Disk-shaped" ("Triangular"/"Flying-wing") aircraft
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 built.
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
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
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
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 was cancelled.
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
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 technical reasons.)
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 wings.
Ho III - 1938 - a metal-frame glider, later fitted with a
folding-blade (folded while gliding) propeller for powered flight.
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 propellers.
Ho VI "flying parabola" - an extremely-high-aspect-ratio test-
only glider. (After the war, the Ho VI was shipped to Northrop for
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
[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,
[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 designated F5U's.
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
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
... 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 thrust.
... 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
E-Mail Fredric L. Rice / The Skeptic Tank