Manufacturer: Lockheed

Model: A-24

Name: Grumbler

Type: Jet interceptor

Date: circa 1974

Status: Prototype

Country: United States

Service: U.S. Air Force (evaluation only)

Designation: none


The Lockheed A-24 Grumbler (an in-house designator) was a spin-off of the Senior Crown program that had spawned the SR-71 Blackbird. It was an unsollicited Lockheed proposal for a fast, high-flying interceptor which built largely on SR-71 Blackbird technology, using the same engine, fuel and other components. Its original feature was to have a circular air intake all around the rear of the cockpit, not unlike the French Coleoptère VTOL prototype of the 1950s.

Three aircraft were assembled but only the first prototype [N681X] actually flew, the second prototype being used for static tests only and the third one being scrapped after 90% of the work had been completed as the design failed to interest the Air Force.

The sole flight-worthy Grumbler prototype was never acquired by the US Air Force and therefore retained its civilian registration. It is seen here in formation with the classic Lockheed TR-1 (U-2RT) Dragon Lady spyplane.

Some say the name Grumbler was an allusion to the aircraft's noise while on approach, but aviation observers see it rather as a tribute to the original fuselage configuration of the Sud-Est Grognard (French for "grumbler") which could have inspired the A-24.


The Grumbler was obtained by isolating one of a Blackbird's two engines with its fin and wing (see below right for original photo). The aft wing was then grafted onto it. The forward cockpit is a mixture of a U-2RT Dragon Lady's nose and a Blackbird's canopy.

Lockheed came up with designs that looked at least as wacky as this, the D-21 Tagboard drone being one. The Grumbler probably has wings that are too small. It could fly very fast in a straight line but would have great trouble landing... unless a set of very large canards can retract from the forward fuselage to somewhat augment to lift surfaces. Well, we can always pretend it DID have them, and they are unseen here because they retracted into the fuselage!!

Viewers' comments:
  • It failed to interest the Air Force? Hey, it is SO interesting, the Air Force seems blind... (Tophe)
  • Looking at the A-24... I think you've actually just shown me how to make a Leduc ramjet plane look good... (dy031101)
  • Maybe this one could be almost as fast as the original Blackbird, due to its smaller weight and size :) Even not being an expert, I bet this one can easily surpass Mach 2 :D (Roddy1990)

My comments: