XSBU-1

The XSBU-1 Scout Dive Bomber evolved from the earlier XF3U-1 two seat fighter. The XF3U-1 was discontinued as the Navy moved from two seat to single seat fighters. The prototype XF3U-1 was stripped of parts that were then used on a strengthened airframe to preform duties as a scout dive bomber prototype. 

XF3U-1 9222 Left Side View 9/18/1933 VAHF photo

Some of the easily identifiable design changes from XF3U to XSBU were engine exhaust routing, the addition of cowl flaps, and bomb displacement gear.

XSBU-1 9222 Left Front View 6/1/1934 VAHF Photo

XSBU-1 9222 Left Side 6/1/1934 VAHF Photo

From Vought Engineering Report 3669 Detail Specification Model SBU-1 Airplane (Class VSB) dated 3/13/35:
 "a single-engine scout and dive bomber landplane for use aboard aircraft carriers. This airplane shall be similar to Model XSBU-1 airplane procured under Contract 34816 from the Chance Vought Corporation."

  

"As a landplane, it shall take off from the deck of an airplane carrier without the aid of a catapult, and land on the carrier deck in an arresting gear, or on an ordinary landing field. The airplane shall not be designed for float type landing gear. The airplane shall not be designed for catapulting." 

XSBU-1 9222 Right Side  9/20/1935 VAHF Photo

The rudder and vertical fin were changed after testing to enlarge the surfaces. Further cowling changes would occur with the production SBUs and the exhausts would be located on the bottom of the cowling and directed downward.

SBU-1 9750 Left Side 8/9/1935 VAHF Photo

An exciting announcement to share on the SBU-1 front, LukGraph is releasing a 1/32 scale Resin SBU-1 in December 2016. I have no affiliation with LukGraph, but am very interested in seeing and building this kit when released. Here is a link to their website if you are interested:

1/32 Resin SBU-1

The following artwork is courtesy of LukGraph.

Previously I did a post on a specially painted and modified SBU-1 which is linked here: SBU-1 Flagship

LSWT - Low Speed Wind Tunnel

In March 1955, Vought dedicated Facility 107 at the Naval Weapons Industrial Reserve Plant Dallas. This was the beginning of the Low Speed Wind Tunnel facility for Vought. 

Aerial view of the LSWL and Hover facilities at NWRIP Dallas just after the 1965 enhancements. (VAHF Collection)

The 1965 additions to the wind tunnel included outdoor and indoor hover facilities. At the time ADAM, C-142 and a whole host of VTOL/STOL designs were begin tested at Dallas.

Outdoor hover facility as part of the LSWT. (VAHF Collection)

The facility was modified again in 1971. The facility has run tests on Vought products and designs from the Regulus, Crusader, Corsair II. Other contracted work included: football stadiums, cars, laser bomb seekers, missiles, parachutes and even the space shuttle.

Fan unit for the LSWT (VAHF Collection)

The following images are a sampling of projects that were tested in the LSWT.

TFX Weapons Integration  (VAHF Collection)

 

B-52 Missile Integration  (VAHF Collection)

Tilt Rotor  (VAHF Collection)

Retractable Roof Sports Stadium  (VAHF Collection)

ACES II Ejection Seat?  (VAHF Collection)

RC-130S Battlefield Illumination Airborne System (BIAS)  (VAHF Collection)

NASA Shuttle Test  (VAHF Collection)

NASA Shuttle Test  (VAHF Collection)

Lockheed Star Clipper  (VAHF Collection)

V-389 More Details

     Continuing with V-389 information is a look at the actual J57-P-4 engine installation into the A2U-1 airframe. This installation drawing shows the placement of the engine and afterburner assembly into the A2U fuselage. 

     Basically aft of fuselage station 265.1 a structural production break the fuselage is new. One major internal change is the changing from a central shear panel (formerly between the two engines) to two shear panels (one on either side of the engine) to absorb fuselage bending loads and fuel inertial loads. 

     All the changes to the fuselage still enable the same wing root rib to be used with the slight exception at the tail cone.

Clip from CVS-37356 V-389 Engine Installation Profile View

Clip from CVS-37356 V-389 Engine Installation Plan View

     Changes to the wing center section was fairly mild. The center-section pylons are moved 9.7 inches aft of the A2U location. The pylons attached to the main wing beam and aft beam instead of the front beam and main beam. 

CVS-37358 V-389 Comparison of V-389 and A2U-1 Plan View

     In addition to the pylons the aft end of the wing root was to be changed to adapt to the new aft fuselage cone for the single exhaust.

CVS-37358 V-389 Comparison of V-389 and A2U-1 Plan View

     Under the skin lighter electrical and hydraulic systems were incorporated. The electrical system would incorporate a separate AC and DC circuits with AC generation taking place by a bleed air turbine generator. Weight would be saved by removing one DC generator, internal battery, and two inverters.

     The hydraulic system incorporated an emergency ram-air-turbine driven hydraulic pump and alternator. The utility system reservoir was redesigned to accommodate the lower fluid volume requirements. One utility system pump was eliminated due to a new higher efficiency pump and the hydraulic oil cooler was eliminated.

     Another subtle change was the installation of only two MK12 guns above the right-hand inlet duct with provisions for a second set over the left-hand inlet duct. 

CVS-37360 V-389 Gun Installation Profile View

The gun muzzles are staggered and located aft of the duct lip instead of in the air duct lip like the A2U-1.

CVS-37360 V-389 Gun Installation Plan View

Source Chance Vought Engineering Report 8847 V-389 Attack Airplane Design Report, NARA II

V-389 Attack Aircraft

  

     A January 1954 Chance Vought V-389 proposal was for an improved performance attack aircraft based upon the A2U-1 Cutlass. The proposal featured a single Pratt and Whitney J57-P-4 engine replacing the twin Westinghouse J46 engines. A new fuselage section from the inlets aft would be required to house the single engine. The V-389 would share major components of the A2U-1 including wings, vertical tails, landing gear and forward fuselage.

The powerplant change caused a significant increase in radius of action, 280 nautical miles for a total radius of 605 NM while using only internal fuel and carrying two 2,000 lb bombs. 

The V-389 equipped with external fuel and a “special weapon*” had a radius of 815 NM.

AIRPLANE	V-389		A2U-1
ENGINE	J57-P-4		TWO J46-WE-18
Loading	Two 2,000 lb Bombs	3,500 lb Store, 300 Gallon Drop Tank and 220 Gallon Fuel Pack	Two 2,000 lb Bombs	3,500 lb Store, 300 Gallon Drop Tank and 220 Gallon Fuel Pack
Gross Weight	34,830 lbs.	38,170 lbs.	33,950 lbs.	37,330 lbs.
Combat Radius (NM)	605	815	325	500
Max Speed, Sea Level Clean Configuration (kts)	598	598	593	593

There appeared to be little official interest in the proposal and eventually the entire A2U-1 program was canceled. The V-389 is left as another interesting “what if”.

Data from Vought Report 8846 NARA II 

*The F7U-3 was cleared in separation tests to carry the Mk 7, 8, 11, and 12 stores.

The A2U-1 cancellation occurred November 19, 1954

Other A2U related posts: (here) (and here)

XTBU-1 Mockup 76 Years Later Part Four

     Here are the images of the tunnel gun installation for lower rear defense of the XTBU-1. Also included in this series is a view from the inside looking at the gun installation. Chance Vought photos from NARA II RG72 collection.

VS-1171-XTBU-1-Mockup--Tunnel-Gun-Sighting-Aft-1940504

VS-1172-XTBU-1-Mockup--Tunnel-Gun-Sighting-Down-1940504

VS-1173-XTBU-1-Mockup--Tunnel-Gun-Sighting-To-Side-1940504

VS-1187-XTBU-1-Mockup--Gun-Turret-Interior---1940504

XTBU-1 Mockup 76 Years Later Part Three

     Continuing on with the series on the XTBU-1 mockup. Here is a series of five photographs that show the turret gun installation. Each of the photos shows the turret in a different position showing it's flexibility and fields of fire for defense of the TBU from upper, rear and side attack, The tunnel gun will be in a further posting. All photos Vought via NARA II RG72.

VS-1636-XTBU-1-Mockup--Gun-Turret-Sighting-Aft---1940727

VS-1637-XTBU-1-Mockup--Gun-Turret-Sighting-Forward-1940727

VS-1638-XTBU-1-Mockup--Gun-Turret-Sighting-Up---1940727

VS-1639-XTBU-1-Mockup--Gun-Turret-Sighting-Up---1940727

VS-1640-XTBU-1-Mockup--Gun-Turret-Sighting-Side-and-Down-1940727

XTBU-1 Mockup 76 Years Later Part Two

     Continuing with the series on the XTBU-1 mockup here are photos of the aircraft in the flight level position, wing folded, from the front and a side view with the cabin enclosure open. Of additional interest is the XF4U mockup with the original tail hook concept sharing the same space in the hangar. NARA II Photos RG 72AC Box101.

VS-1121-XTBU-1-Mockup-Torpedo-Bomber-Flight-Attitude-1940504

VS-1138-XTBU-1-Mockup-Torpedo-Bomber-Rear-View-Wing-Folded-1940504

VS-1139-XTBU-1-Mockup-Torpedo-Bomber-Front-View-1940504

VS-1140-XTBU-1-Mockup-Torpedo-Bomber-Front-View-Wing-Folded-1940504

VS-1141-XTBU-1-Mockup-Torpedo-Bomber-Left-Side-Cabins-Open-1940504

XTBU-1 Mockup 76 Years Later Part One

     Vought's entry in the competition to replace the Douglas TBD torpedo bomber became a footnote in history due to the success of it's stablemate the F4U and the lack of production space at the factory. The aircraft was sleeker and provided better performance than it's Grumman competitor the XTBF-1. 
     Production rights were transferred to Consolidated as the TBY-2 and eventually less than 200 were manufactured before the end of the war caused contract cancellation.

     Here are the mockup photos of the XTBU-1 taken on May 4, 1940 showing the design from several different angles. Photos are from NARA II Collection 72AC Box101C.

VS-1120-XTBU-1-Mockup-Torpedo-Bomber-3-Point-Attitude-1940504

VS-1137-XTBU-1-Mockup-Torpedo-Bomber-Rear-View-1940504

VS-1147-XTBU-1-Mockup-Powerplant-and-Fixed-Gun-Right-Side-1940504

VS-1154-XTBU-1-Mockup-Torpedo-Installation-1940504