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

End of the Biplane Series

     It is fairly well documented that in 1934 the US Navy issued the requirement for a new Scout Bomber. This was at the time the Navy was starting the transition from biplane to monoplane aircraft.

     The XSB3U-1 was built as hedge against the Navy not accepting the XSB2U-1 Vindicator in the 1934-35 time frame. There was discussion about monoplanes being too large to handle on deck, high approach speeds, and longer take-off distances, some of the same arguments in the discussion of progressing from propeller driven aircraft to jets just about 10 years later.

3617-XSB3U-1-9634-Right-Side-View-19360228 VAHF Archives

     The top speed for the XSB3U-1 was listed at 215 mph which meant the retractable landing gear bought approximately 10 mph over the previous SBU-1/-2 aircraft that it was intended to replace. That speed was a good 30 mph slower than the SB2U-1.

3620-XSB3U-1-9634-Left-Rear-View-19360228 VAHF Archives

     One XSB3U-1 was built and the contract went to Vought to build the SB2U series. Here is a general arrangement for the XSB3U-1 from the Vought Heritage Archives

    

     In the end the XSB3U-1 was the last vestige of the biplane dive bomber line at Vought that started with the end of another era, the two seat fighter (pilot and rear gunner) XF3U-1. The XSBU-1 was the XF3U-1 prototype re-purposed into the dive bomber series SBU-1 and SBU-2.

Flag Plane SBU-1 Bureau Number 9815

Here is another excellent example of a Flag Plane for a Senior US Naval officer.
This SBU-1 (9815) photographed about four years after the SU-2 I posted in a earlier installment. (here)

Chance Vought photo of SBU-1 9815 on April 10, 1936.

The aircraft is Admiral Blue with Aluminum tail surfaces. It differs from a standard SBU-1 having wheel pants, a rank placard holder on the fuselage side and changes to the rear cockpit. Unlike the SU-2 photos there is no hiding the tailhook on this beauty!