Northrop YB-49 Flying Wing Bomber - Virginia Techmason/Mason_f/NorthropYB-49.pdf · Northrop YB-49...
Transcript of Northrop YB-49 Flying Wing Bomber - Virginia Techmason/Mason_f/NorthropYB-49.pdf · Northrop YB-49...
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Northrop YB-49Flying Wing Bomber
Chris Conrad
Matt Eluk
Liz Craig
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Mission / Purpose
Jet Powered Variant of
the XB-35
Northrop XB-35 was
the 13th flying wing
flown by the company
Designed as a long
range, heavy bomber
meant to compete with
the Convair B-36
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Mission / Purpose
XB-35 design was
commissioned during WWII
to have a range of 10,000
miles carrying 10,000lbs of
bombs.
Original mission called for a
bomber that could operate
from the western
hemisphere and bomb
Europe without refueling.
XB-35
www.volny.cz/kletectvi/ northrop.htm
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Mission / Purpose
Why a Flying Wing?– Jack Northrop was a HUGE believer in the idea
for years
– Large internal volume (fuel and payload)
– Simplified Structures
– Extremely low drag possible!
– Earlier stability and control studies showedconcept was viable
– Subsonic mission
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Mission / Purpose
XB-35 was classified as a heavy bomber
YB-49 promised greatly improved
performance over it’s piston driven
predecessor in terms of speed
Sacrifice in range was deemed acceptable
YB-49 was eventually classified as a medium
bomber
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Mission / Purpose
Alterations from XB-35
– Piston/prop propulsion
replaced with 8 Allison J35-
A-5 turbojet engines
– Slot intakes cut into leading
edge of wing
– Four vertical surfaces
added; two inboard of
engines and two outboard
– Wing fences Added
– All guns removed except for
those in tail stingerwww.globalaircraft.org/planes/ yb-49_flying_wing.p
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History
June 1, 1945 – First two XB-35 to YB-49 conversions commissioned.
Maiden flight of first YB-49: October 21, 1947 Maiden flight of second:January 13, 1948
Both based at Muroc AFB for testing
20 month test flight program conducted with both AF and Northroppilots
– 144 flights flown by Northrop pilots
– 25 flights flown by Air Force pilots
April 26, 1948, the first YB-49 achieved a milestone of sorts, theaircraft staying up in the air for 9 hours, 6 hours of which were above40,000 feet. (unofficial record for the time)
June 5, 1948, 2nd YB-49 crashes killing all aboard including Capt.Glenn Edwards. Investigation suggested Edwards surpassed the Vne.Muroc AFT renamed Edwards AFB.
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History
Air Force decided to continue program
Bombing tests show accuracy worse than older B-29. Instability
issues frustrate pilots and crews.
1948, YB-49 down-graded to medium bomber. Now competes with
XB-46, XB-47, and XB-48 projects instead of B-36.
1949, YB-49 ordered on publicity tour.
– Possible sabotage during trip
– Engine fire during flight caused by oil drain from engines. Appeared to be
intentional.
March 15, 1950, program officially cancelled.
March 15, 1950, same day program is cancelled, first YB-49 suffers a
failure during taxiing and is destroyed
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YB-49 Specifications
4000 mi with bombsRange
420 mph / 495 mph (520
mph record speed)
Cruise speed / Max speed
32,000 lb (total)8 Allison J35-A-5 turbojet engines
213,500 lbMax takeoff weight
15,000 lbMax payload
172 ftSpan, b
4000 ft2Area, S
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YB-49 Final Configuration
www.globalaircraft.org/planes/ yb-49_flying_wing.p
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Planform / Airfoil Issues and Analysis
4000 ft2 (371.6 m2)Wing Area (total)
R.C. 37.5 ft (11.4 m)
T.C. 9.33 ft (2.8 m)
Chords
T.C. NACA 65,3-018Tip Airfoil
R.C. NACA 65,3-019Root Airfoil
315" (210" Aft Sta 0) (CG @ 35.4% MAC)M.A.C
26o57'48" LE
10o15'22" TE
Sweep
85.5 inches at root chordWing Thickness
0° 53' at Leading EdgeDihedral
0 deg at root chord
-4 deg at tip chord
Incidence
4:1Taper Ratio
7.4:1Aspect Ratio
53.08 ft (16.2 m)Length
172 ft (52.4 m)Span
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NACA 6
http://www.engr.utk.edu/~rbond/N653-018.pdf
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Planform / Airfoil Issues and Analysis
CL Cruise = 0.118
CL Max = 1.2 (clean)
Cd0 = 0.00608
for Mach = 0.2
Cd0= 0.00601
for M = 0.50
0.5
1
1.5
2
2.5
3
0 0.1 0.2 0.3 0.4 0.5
Drag Coefficient
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M = 0.8
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Planform / Airfoil Issues and Analysis
Tornado Analysis
624 Panels
– 12 chord-wise divisions
– 26 divisions across half-
span
Tornado
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Planform / Airfoil Issues and Analysis
Tornado Tornado
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Planform / Airfoil Issues and Analysis
10 % Static Margin Instability
Elevons/Trim Flaps to trim
– Small moment arm (no tail)
Split Drag Rudders
Vertical surfaces still did not provide enough yaw
stability (first aircraft to incorporate an artificial
stability system as a result)
Flow field with bomb bays open turbulent
– Decreased bomb accuracy
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Overall Assessment
Poor fuel efficiency reduced range and payloadcapabilities
Increased max speed by 100 mph over XB-35
Eliminated vibration due to piston engines (fixedgearbox problems)
Long range and high cruising altitude goals requiredby Air Force were not fully met
Test pilots complained that it could not hold a steadycourse or a constant airspeed and altitude
“It was the wrong airplane at the wrong time…”
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Concluding Thoughts…
Good Idea at the wrong time
Stability issues were likely unsolvable with thetechnology available
Provided valuable data on radar cross-sectionreduction associated with flying wings
Amazing resemblance to later B-2
Even if stability problems had been solved, it isquestionable whether or not it would have beenadopted by the Air Force given Convair’sinvolvement.
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References
http://aerospaceweb.org/aircraft/bomber/yb49/
http://www.globalsecurity.org/wmd/systems/b-49.htm
pages.nyu.edu/~jh15/ images/b36-1.jpg
http://www.nurflugel.com/Nurflugel/Northrop/yb-49/body_yb-49.html
www.volny.cz/kletectvi/ northrop.htm
www.danford.net/ northrop.htm
avions.legendaires.free.fr/ Images/imagemai02.jpg
www.globalaircraft.org/planes/ yb-49_flying_wing.p
http://www.engr.utk.edu/~rbond/N653-018.pdf
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References
http://www.nurflugel.com
http://home.att.net/~jbaugher2/b49_1.html
Edward T. Maloney, Northrop Flying Wings, World
War II Publications, 1988.
Ford, Dan; "Flying Wing"; Smithsonian Air & Space;
Jul 1997