wb9omc@ea.ecn.purdue.edu (Duane P Mantick) (11/08/89)
From: wb9omc@ea.ecn.purdue.edu (Duane P Mantick) On the question of nuclear powered aircraft, there was a B-36 that was modified to carry a nuclear reactor. I do not know too many details but I can tell you that the Squadron/Signal book about the B36 does give some info. on the subject. If I think about it, I will bring it in sometime and submit the info. to the moderator for potential posting. As far as the B58 is concerned, a "normal" mission would in fact carry a crew of three along the lines of Pilot, Navigator(+ other functions) and Weapons Systems Operator. I, too reacall the sight at Grissom and went to one open house back when the B58's were still operational there (305th bomb wing, methinks). It was quite a sight and sound to have a formation of 6 of those dudes overfly the base - that was an airplane with real guts! You didn't hear it as much as FEEL it. Of course, this was also in the days when the Thunderbirds were flying the F100 Super Sabre, I believe D variant - this was also a LOUD airplane (they were at the same open house, I think...I don't remember if it was the day they rededicated the base from Bunker Hill AFB to Grissom AFB or not). As a matter of interesting (I hope) trivia, the 305th was one of only two operational wings to fly the B58 with the other being the 43rd out of Little Rock, ARK., I think. Duane
thomasw@doyle.cs.concordia.ca (11/17/89)
From: thomasw@doyle.cs.concordia.ca
The following is from Chapter 10: The Convair X-6 of _The X-Planes_ (X-1 to
X-31) by Jay Miller, greatly abbreviated and paraphrased and therefore, I
hope, acceptable for posting.
The Convair X-6
---------------
Manufacturer:
Convair Division of General Dynamics (X-6 airframe, based on B-36)
Aircraft Gas Turbine Division of General Electric (P-1 nuclear powerplant)
In 1951, GE was awarded an Air Force contract to develop a nuclear turbojet
engine and an Atomic Energy Commission contract to develop a nuclear reactor
to be used for aircraft propulsion. The resulting powerplant, named the P-1,
was an air-cooled nuclear reactor using metallic fuel elements and water as
a moderator and coolant.
Also in 1951, Convair was awarded an Air Force contract to modify two B-36H
airframes (redesignated the X-6) to carry the P-1 powerplant, and a third
B-36H to be used for shield testing. The aircraft were to be used to evaluate
the practicability of nuclear propulsion systems, including reactor shielding
and radiation effects on crew and electrical systems.
The X-6 never got past the design stage, but the shield test aircraft was
built and subsequently flown as the Nuclear Test Aircraft (NTA), designated
as NB-36H (AF serial number 51-5712).
History:
First AF interest in nuclear propulsion in 1944 led to the establishment of
the Nuclear Energy for Propulsion of Aircraft (NEPA) project at Fairchild
Airplane and Engine Company in 1946, which was later joined by the AEC and
the Navy. NEPA was dissolved in 1951 and replaced by the (expanded)
Aircraft Nuclear Propulsion (ANP) program; ANP was permanently cancelled
in 1961.
A study in 1948 (Lexington Report) suggested that nuclear propulsion was
feasible, but that it would require a 15-year, 1-billion-dollar effort.
AEC then asked DoD to establish the military need for nuclear powered
aircraft before embarking on such a large effort; as a consequence of
the political situation, a long-range strategic bomber was deemed a
necessity and the Air Force was given the go-ahead. The original goal was
a extreme-range supersonic bomber, later scaled down to the X-6 subsonic
testbed.
Several reactor designs (using liquid-metal, air, and high-pressure water
cooling) were competing with each other, with the air-cooled design the
eventual winner. Design difficulties (no material could withstand the
proposed temperature of 2500 F) led to a lowering of the reactor's operating
temperature to 1800 degrees F and thus to a lowering of the reactor's power
output. This, and concerns about the slow spool-up/down times of the reactor,
led to the inclusion, in the design, of conventional jet engines to serve as
auxiliary powerplants and to provide additional thrust during take-off.
The design thus called for four turbo-jet engines to be connected to the
reactor, which would produce 26,000 lbs thrust at 15,000 feet using reactor
heat, but which would retain their combustion chambers for burning chemical
fuels; this would propel the aircraft to speeds from 300 to 390 mph. The
propulsion system was to weigh around 165,000 lbs (10000 lbs reactor,
60000 lbs reactor shielding, 37000 lbs crew shielding, 18000 lbs engine,
40000 lbs piping and accessories).
There followed a series of technical problems (low power output, high shielding
weight, piping problems), design changes (different airframes, different
engines, different reactor/propulsion designs), changes in program direction
(finally to include manned aircraft, nuclear rockets, and nuclear ramjets), and
funding difficulties, which by 1961 resulted in the cancellation of the program
after expenditures of about 470 million dollars.
The only flying hardware that came out of the program was the above-mentioned
NB-36H Nuclear Test Aircraft, which made its first flight in September, 1955.
The aircraft had a totally redesigned nose section to accomodate the 12-ton
shielded crew capsule and a redesigned fuselage to hold nine water-filled
shield tanks and test instrumentation. The aircraft carried a 35000 lbs,
one MW reactor mounted in the aft bomb bay, which could be removed after
each flight for examination and ground testing (and continued cooling).
The NB-36H completed a total of 47 flights between September 1955 and March
1957, examining "radiation shielding methods and materials, radiation effects
on aircraft materials and components, and nuclear ground and flight operations."
The reactor was never used to power any of the aircraft's engines or systems,
even though it was made critical and power was generated during flight. (The
last sentence seems to contradict itself, but that is what it says in the book).
>From the pictures in the book and their legends, I could glean the following:
- the aircraft had two fairly big air intakes added on the sides of its aft
fuselage (about halfway between the wing and the tail), complemented by two
large exhausts on the top of the fuselage
- the crew capsule could only be entered through a special hatch at the top,
which due to its weight could only be opened mechanically (forget about
bailing out)
- the cockpit windows were fairly small and consisted of a 9-11 inch thick layer
of water; visibility was very limited
- the reactor was stored in a special pit in the runway at Convair's Fort Worth
plant which was covered by track-mounted lead doors. From there it could be
installed in the NB-36H bomb bay by positioning the aircraft above the pit
and winching the reactor into the bomb bay
Just because some previous posters mentioned the prohibitive weight of reactor
shielding, I want to add the following data from the design of the X-6:
Gross weight: 360,000 lbs; empty weight: 225,000 lbs.
Reactor shielding:
- main forward shield: 103 foot, 12 foot diameter tank of pressurized water
- forward gamma shield: 80-inch diameter, 4 inch thick circular lead shield
- side shield: 2.5-inch thick layer of polyethylene plastic, double-walled
fuselage
Crew shielding (note that this is ~60 foot forward of the reactor!):
- cylindrical, 14 foot long and 6.75 foot diameter, with small cutout for
12 inch thick water window in front
- .25 inch lead and 9 inch plastic lining in front
- 2.5 inch lead and 21.5 inch plastic in rear (ie. towards reactor)
- 0.25 Roentgen hourly charge into crew compartment
One thing I wonder is how much radiation escaped sideways out of the fuselage
(the side and aft shielding is pretty flimsy compared to the massive frontal
shielding) and how much radio-active exhaust was produced, but it doesn't
give that data in the book. According to the description and the drawings
of the reactor in the book, the air was going straight through the reactor
core, heated up by the hot fuel rods.
Sorry if this is a bit long, I hope it's of interest.
Thomas
Thomas Wieland Email: thomasw@jupiter.cs.concordia.ca
Dept. of Computer Science or: thomasw@concour.cs.concordia.ca
Concordia University
Montreal, PQ Canada Phone: (514) 848-3039
[PS: Bill, regarding the German pocket battleships (in 50 Years ago),
the correct use of the word is: one "Panzerschiff", two "Panzerschiffe"
-- just nit-picking, I really enjoy your series. ]