__NOTOC__ The Boeing NB (or Model 21) was a primary training aircraft developed for the United States Navy in 1923. It was a two-bay, equal-span biplane of conventional configuration with interchangeable wheeled and float undercarriage. The pilot and instructor sat in tandem, open cockpits. The NBs were produced in two batches; the first (NB-1) were powered by radial engines and the second by war-surplus V-8s still in the Navy's inventory. The original prototype evaluated by the Navy had been assessed as being too easy to fly, and therefore of limited use as a trainer. In particular, it was noted that the aircraft was impossible to spin. The NB-1 design attempted to introduce some instability, but it was soon discovered that while it was now possible to get the aircraft into a spin, it was virtually impossible to recover from one. A series of modifications were made to attempt a compromise.

Variants

* VNB-1 - prototype (one built) * NB-1 - original production machine with Lawrance J-1 radial engine (41 built) * NB-2 - production machine with Wright-Hispano E engine (30 built) * NB-3 - one NB-1 with lengthened fuselage and modified empennage to improve handling, and Hispano-Suiza E engine. Later refitted to standard NB-1 * NB-4 - one NB-1 converted similar to NB-3, but with Lawrance J-1 engine. Later refitted to standard NB-1

Operators

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United States Navy The United States Navy (USN) is the naval warfare, maritime military branch, service branch of the United States Department of Defense. It is the world's most powerful navy with the largest Displacement (ship), displacement, at 4.5 millio ...

; * Peruvian Naval Aviation (NB-1)

Specifications (NB-1)

References

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External links

Boeing training seaplane : model NB-1
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The Museum of Flight Digital Collections
{{USN trainer aircraft 1920s United States military trainer aircraft NB