Boeing EX

Aviation Week & Space Technology , November 20, 1992, Pages 62 & 63

Boeing Pursues Innovatitive Concept for Future Navy EX
By Breck W. Henderson/seattle

WHAT IS BELOW IS MY SUMMARY OF ABOVE ARTICLE - Any mistakes are my own and not the original author.

Boeing Military Airplanes early concept of replacement for Grumman E-2C Hawkeye.
Dubbed the EX it is designed around an innovative & unusual, joined-wing airframe, the joined
wing surface also mounts AESA with a huge effective area giving 360-deg. view and imroved
detect range.
Earlier The Advanced Tactical Support Aircraft (ATSA) to replace the E-2C, S-3 ASW and EA-6B cancelled for lack of funding.
Boeing built/tested 1/5th scale radar model.
Boeing verified aircrafts landing charatistics via wind tunnel tests.
design of s3 alternative features a l-band AESA in a triangular radome, texas instruments
designed.
EX additional missions, strike support, intel gathering, Aera defece vs cruise missiles &
theatre ballistic missile defence.
additional possible sensors include:
-Shared AESA rada, mounted on leading edges for L, S & C bands for passive, bistatic mode; ESM, elint & signit; ECM; multiple commo links like to Aegis for fire control; nav & Iff modes.
-nose x-band for search & rescue, precision tracking & illumination for Surfa-2-Air seekers.
infra-red IRST, as on E-2 for precision tracking.
-ESM operating in HF thru K bands, providing ESM info.
-primary, UHF radar antenna area of 600 sq.ft operating in UHF band (300-600 MHz), resulting
in ranges 2.5 times that of E-2.
-Radiates to 160 kw. UHF detect target with 1 sq. meter cross sectioon at 400-600 mi. Smaller
at 175-250 naut. mi., cruise missile types targets at 6ft at 125-150 naut. mi. Scud type at
400-600 naut. mi.

Specs:
Gross Weight = 55200 lbs
operating weight = 35380 lbs
length = 51 ft-2 in
height = 18 ft-6 in
wing span = 63 ft-4 in (29 ft-1in folded)
wing area = 845 sq ft
spot factor = 1.34 (F-18 reference)
TF34-400 Engines(SLST = 9,2t5 lbs each)
T700 GE-401 turboshaft enine for radar power (1690 eshp)
Loiter at Mach 0.38, sprint at Mach 0.76, cruise to a max range of 2.590 naut. mi.

LINE DRAWING PICTURE LATER

Pics of one of the Boeing models, I saw this model a few years ago at a Phantom Works touring exhibit at the Everett plant, back when I worked electrical design on the 747-400.

Cheers, Jon

Here is a photograph dated 1993 of the EX model in a NASA windtunnel, with the caption:

The photograph shows a model of the Boeing EX Concept installed in the NASA Langley 16 foot Transonic Tunnel. The Boeing EX is an advanced surveillance aircraft proposed by Boeing to replace the Grumman E-2C Hawkeye. The concept employs the diamond-shape "joined-wing"planform and active aperture radar arrays in each wing segment to create a more aerodynamic effective surveillance aircraft. Wind tunnel testing was conducted to evaulate longitudinal and lateral aerodynamic charcteristics and the effectiveness of control surface deflections. Measurements were made to determine the effects of the wings and fuselage on the inlet fan face total pressure distortions at angle of attack and sideslip.

Nice photos of a beautiful model Jon - thanks for posting them. I remember seeing this in Av Week and in Popular Mechanics. Would have been interesting...

Enjoy the Day! Mark

Seems to be old known shapes arised from my harddrive...

Boeing artist's impression of 'EX'

Joined wing EX was one of the nine concepts, studied under NASA RevCon program, dubbed 'Joined Wing Integrated Structures Flight Demonstrator'.

Photos (c) Retro Rocket

Boeing artist's impression (first image) of EX.

Three-view drawing (second image) of Boeing EX.

Boeing tested a one-quarter-scale model of the EX's conformal radar (third and fourth images).

Source: Dane, Abe. "Diamond Eyes" Popular Mechanics September 1993 p. 32

I fell in love with the Boeing EX concept the moment I saw it in AW&ST back in 1992. Does anyone know what caused the demise of the program? And is the Sensorcraft program that also uses the rhomboid wing still going on?

those old PMs and PopScis are real goldmine

I look at that design and it makes me wonder just how they planned to fold the wing? They can't just fold it like normal as the wing roots are on different heights.

Boeing EX

Type: Carrier-compatible maritime surveillance and early warning aircraft.

Program: Design study began in 1988; present configuration announced late 1992; intended to compete for US Navy E-X requirement for E-2C Hawkeye replacement early next century; however, requirement delayed by 1994 decision to maintain Hawkeye production beyond 2000.

Design features: Joined-wing diamond planform (high-dihedral front wing, anhedral rear wing) chosen primarily to obtain best results from conformal, active phased-array antennae; radar already tested in one-fifth scale model with satisfactory results; wing rooted at mid-point of front fuselage and single fin, and joined near tips; engines pylon-mounted amidships, with third engine internally for electrical power generation; configuration provides radar with 360 degree scan and enhanced detection range. Wing sweep angle 40 degrees backward on front leading-edge and 40 degrees forward on rear wing trailing-edge, dictated by radar scan angle.

Wings foldable for carrier stowage; two underwing stations for ESM pods, drop tanks, or other stores.

Power plant: Two 41.3 kN (9,275lb st) General Electric TP34-GE-400 turbofans, or more powerful derivative, pod-mounted on sides of center-fuselage.

Accommodation: Crew of four (pilot and three sensor operators), all on ejection seats.

Systems: 1,260 kW (1,600 shp) General Electric T700-GE-401 turboshaft, mounted in fuselage, serves as APU to generate electrical power for radar. Conformal antennae along virually full span of all four wing surfaces. Wide variety of other sensors could be carried for several alternative missions.

Dimensions external
Wing span: 19.30 m (63 ft 4 in)
Width, wings folded: 8.86 m (29 ft 1 in)
Length overall: 15.59 m (51 ft 2 in)
Height overall: 5.64 m (18 ft 6 in)

Areas
Wings, gross: 78.50 sq m (845 sq ft)

Weights and loadings
Operating weight empty: 16,048 kg (35,380 lb)
Max T-O weight: 25,537 kg (56,300 lb)

Performance (estimated)
Max level speed: Mach 0.76-0.80
On-station patrol speed: Mach 0.38

Range
Internal fuel only: 2,590 nm (4,797 km; 2,980 miles)
With two 1,514 liter (400 US gallon; 333 Imp gallon) external tanks: 2,970 nm (5,500 km; 3.418 miles)

Source: Lambert, Mark ed. Jane's All the World's Aircraft 1992-1993 Jane's Information Group Ltd. 1992 pp. 517-518.

Stargazer2006 said:

I fell in love with the Boeing EX concept the moment I saw it in AW&ST back in 1992. Does anyone know what caused the demise of the program? And is the Sensorcraft program that also uses the rhomboid wing still going on?

Click to expand...

Money and internal Navy politics.

The Navy was desperately short of funds in the 1990s. EVERYTHING went out the window except F/A-18 E/F. On top of this, there was a fight between the E-2 and S-3 communities. The former won...and defined the Common Support Aircraft program in such away that it was identical to an E-2.

Don't know if this fits here, but I have found this old British concept, the Hall-Warren S31-1 in a book and wonder if this would qualify as a joined wing or rhomboid wing aircraft...

NASA has released seventeen great pictures of Boeing's EX project in wind tunnel model form:

http://crgis.ndc.nasa.gov/historic/Test_453:_Boeing_EX

http://crgis.ndc.nasa.gov/historic/Test_511:_Boeing_Joined_Wing_Ex

Artist's impression of Boeing EX concept.

Photographs of wind tunnel model.

NOTE: Larger version of artist's impression and photographs available at source website.

Source:
http://crgis.ndc.nasa.gov/historic/Test_511:_Boeing_Joined_Wing_Ex

Snapshots of Boeing EX Surveillance System Concept brochure.

Source:
http://crgis.ndc.nasa.gov/historic/File:1998-10-05_-_Boeing_EX_Surveillance_System_Concept.pdf

joncarrfarrelly said:

Pics of one of the Boeing models, I saw this model a few years ago at a Phantom Works touring exhibit at the Everett plant, back when I worked electrical design on the 747-400.

Cheers, Jon

Click to expand...

This model is now on display at the Boeing Store inside the Future of Flight Aviation Center at Paine Field in Mukilteo, WA.

Triton said:

This model is now on display at the Boeing Store inside the Future of Flight Aviation Center at Paine Field in Mukilteo, WA.

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Joe Kunzler (AvgeekJoe) posted 2 pictures of the Boeing EX model at Flickr. The pictures were taken during his 2012 trip to Future of Flight Aviation Center at Paine Field (KPAE) in Mukilteo, WA.


https://www.flickr.com/photos/avgeekjoe/9045973473/sizes/l/
https://www.flickr.com/photos/avgeekjoe/9048199122/sizes/l/

Model of Boeing EX.

The EX model is still hanging in the gift shop at the Future of Flight museum (as of February 28, 2018). It's painted in VS-24 markings with an S-3A Viking BuNo, 160137.

Robert said:

The EX model is still hanging in the gift shop at the Future of Flight museum (as of February 28, 2018). It's painted in VS-24 markings with an S-3A Viking BuNo, 160137.

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Hmmm...does that imply it is able to be purchased?

Missions listed include "Ballistic Missile Defense, and Air Superiority."

Such an interesting aircraft this would have been!

The overall layout seems adaptable/useful to many different roles:

1. 6th gerneration fighter?

2. Tanker?

3. 737 replacement?

kcran567 said:

Missions listed include "Ballistic Missile Defense, and Air Superiority."

Such an interesting aircraft this would have been!

The overall layout seems adaptable/useful to many different roles:

1. 6th gerneration fighter?

2. Tanker?

3. 737 replacement?

Click to expand...

I agree it is very interesting design and I love it.

And I also thought joint wing is useful for #2 and #3 because it is expected to have advantage in lift/drag ratio and structural fatigue aspect, and this is why Boeing chosen this design for long-time endurance aircraft. But, sill, complex control of CG, and engine position could be trouble some phenomena when the design of the aircraft is matured.

Additionally, rear wing part tends to be lower or higher position than front wing to avoid downstream of the front wing which degrades performance and handling qualities or stability. In that design, if rear wing is swallowed by downstream of the front wing, aircraft could enter the severe departure status than the conventional ones. Because of that joint wing design is hard to be planform of the 6th generation fighter or similar things which needs high maneuverability.

Very helpful review paper for joined-wing

https://www.sciencedirect.com/science/article/pii/S0376042116300471

litzj said:

Very helpful review paper for joined-wing

https://www.sciencedirect.com/science/article/pii/S0376042116300471

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Not so much, not really.

I am not sure that structurally this is an ideal solution. At each point of time, one wing is in extension while the other is buckling. Given that the link b/w the two are rigid, there are a lot a complex behavior to ascertain with their inherent implication on flow paths or fuselage oscillation just to complicate the matter. But I am sure that Boing solved that all

Demon Lord Razgriz said:

I look at that design and it makes me wonder just how they planned to fold the wing? They can't just fold it like normal as the wing roots are on different heights.

Click to expand...

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Agreed, folding at wing roots would be ridiculously complicated.
A lighter option is folding wings at mid-span. At least one 3-view drawing shows possible hinge lines about mid-span. Start by determining the maximum wing span that will fit in existing elevators. Hint: Viking S-3 folds to a width of 29.5 feet. Draw the hinge axis across both leading edges. Hinge the wings up and inboard. Hangar height determines whether they stow straight up (MD/Boeing FA-18) or lay on top of the fuselage (Grumman Tracker). The advantage of folding well outboard ( maximum span that will fit in elevator) is lighter weight hinges. The disadvantage is complex locking mechanisms like the Tracker, which has a dozen-ish pins locking wing skins in the extended position.

On another mission, I wonder how difficult it would be to convert EX to the tanker and COD roles????? Yes, we know that a few S-3 Vikings flew those roles late in their service lives. The big challenge for a COD is installing a tail ramp large enough to accommodate a fully-assembled jet engine. Given the slender aft fuselage of EX models, that would require a completely new aft fuselage.

Wind tunnel model （ 2001）：