Boeing Model 299 "XBBR-1"

At some point early in its career the Air Corps designated the Boeing Model 299 the "XBBR-1".

Does anyone know what this acronym means and where it came from?

AlanG

XBLR-1 - turned into the XB-15

I'm familiar with the XBLR-1 through 3, and at least one other I suspect to be an unsuccessful entry by another company.

The Model 299 design came along after the XBLR-1/XB-15. This appears to be a completely separate designation specific to the Model 299. I'm hoping to get a copy of the document in which it is mentioned sometime soon.

AlanG

Sounds like a typo to me?

XBLR was "Experimental Bomber, Long Range"
XBMR or XBSR would make logical sense but I can't see a way to make an acronym of XBBR.

Paul, that occurred to me, too. The only problem I have with that is the source of the question. He is going to try to find the original reference and send it to me.

That is actually the source of the question. He and I both know that the XBLR projects had nothing to do with the 299 or subsequent models.

AlanG

In my many years of looking into US military designations I have never run across BBR-1. So I am interested in the source of that information.
In the meantime, these are the BLR designation – note that XBLR-1 was the Boeing 294.

BLR-1: Boeing 294

On 28 June 1934 a contract was placed for one XBLR-1 with serial 35-277. On 29 June 1935, and prior to the first flight of the aircraft, the designation was changed to XB-15.

BLR-2: Douglas

Ordered on 9 July 1935 as XBLR-2, the design had initially 6 engines. In March 1938, by which time the design had evolved into a four-engined aircraft, the designation was changed to XB-19. At that time no aircraft had yet been ordered.

BLR-3: Sikorsky

Also known as project M5-35, a design was submitted on 29 February 1936 whilst a wooden mock-up was built in March 1936. The design was rejected in favour of the BLR-2. No aircraft were ordered.

Answer revealed!

The original document has been found once more and here is the story.

First, it was a typo in the letter, which was referring to the XBLR.

HOWEVER, the letter was also talking about the Boeing Model 299 instead of the 294 as it should have.

History is odd.

AlanG

Jeepers, I should have picked this up earlier.
The Boeing 299 was, of course, the B-17. The first B-17, commonly and unofficially referred to as XB-17, had no military designation or serial and carried the civilian registration NX13372.

I'm going to pretty much repeat what has been said here before, but:
1°) "XBBR-1" seems pretty much like a typo to me,
2°) XBLR-1 was indeed the Model 294, not the Model 299,
3°) if BLR was an acronym for "Bomber, Long-Range", there is no possible explanation for what "BBR" might have been.

At best, "XBSR-1" might have made some sense for the Model 299 prototype as a "Bomber, Short-Range" if designated in the short period of time when the XB-15 was known as the XBLR-1... Highly logical, but I've never seen it or heard about it.