The Model 35A/36A featuring a slightly lengthened fuselage and turbofan engines.

The prototype Sea Patrol model of the Learjet 35A, which has made a number of overseas demonstration tours since it was completed in 1979.

The different fuselage lengths and different engines of various of the Learjet models are visible in this photograph of, front to rear, a Learjet 35, Learjet 25B and Learjet 24D.

The prototype Longhorn 50, in the foreground, keeps company with a Learjet 35A with Century III wing modifications.

Comparative side profiles of the Learjet prototype (note single nosewheel door); the production Model 23 and original Model 24/24B; the Model 24D/E/ F with tailplane/fin acorn deleted and tip-tanks drooped (4th cabin window on late models only); Model 25 original form; Model 28/29 Longhorn; Model 35/36 (5th cabin window on late models only) and Longhorn 50 series.

The smallest is the Model 25D, which remains in production in 1980

The Learjet 25B of the Fuerza Aerea Boliviano showing the special camera installation in the front fuselage.

This Learjet 25C sports a somewhat different camera installation, mounting two wide-angle Zeiss cameras. Under ideal conditions, up to 23.000 sq mis (60.000 km2) can be photographed in a working day by this aircraft.

The two original prototypes of the Learjet 23 in flight over Wichita, the first aircraft being farthest from the camera.

An early-type Learjet 24 (with fin/acorn fillet) in which Clay Lacy and Dwight Brooks, with three other crew members, won the London-Victoria air race in 1971.

One of Swed-Air's two Learjet 24s fitted out as target tugs, with the target stowed under the rear fuselage and an ECM pod under the front fuselage.

In the drawings, the three-view, including the uppermost side view, shows the SAAC-23 in the form in which it was first publicised. Subsequently (second side view) it was lengthened and the tail plane was moved down, but a T-tail had been re-adopted by the time construction of the prototypes was launched, as shown in the side view at bottom.

The Gates Learjet Longhorn 50-series prototype on an early test flight during 1979.

The Longhorn 50 is the largest ' ‘stretch'' of the basic Learjet to date, with fuselage deepened and widened, as well as lengthened.

A formation of three early Longhorns. In the lead is the original Longhorn 28 prototype after it had been fitted with a production wing; beyond it is a converted Learjet 24 fitted with the original prototype wing and in the foreground is the first production Longhorn 28.

The prototype of the Learjet Longhorn 50 series on an early test flight.

The first and second prototypes of the Longhorn 50 photographed in late 1979, showing the Softlite-system wing fences that had by then been adopted.

Gates Learjet Series 50 Longhorn

The three-view is representative of all models of the Learjet Longhorn 50 series.

One of the handful of Longhorn 28/29s delivered during 1979, before production was temporarily halted to allow maximum effort to be deployed on the Longhorn 50 series.
The Learjet Model 28/29 "Longhorns" were the first in the series wi th a wing optimised for long-range high-altitude operation.