Lavochkin La-5 In Soviet Service. Part four.

 

In the summer of 1943 a two-seater variant of the La-5F was adapted by the Lavochkin Design Bureau. The La-5UTI (which stands for 'Fighter-Trainer' in Russian) was a simple adaptation of the single seat La-5F with a second cockpit placed just aft the radio bay. Instructor's cockpit was equipped with duplicate flight controls and the front cockpit ones (where the pupil sat) were automatically disconnected every time the instructor took control. Both cockpits were fully enclosed by sliding canopies. 
Given its non-combatant role, the La-5UTI lacked many features when compared to the fighter, as many were deleted to save weight. Armor glasses behind windscreen, pilot's head and the back seat were eliminated, as well as the wing fuel tank fire suppression system. The small cockpit air inlets in front of the canopy, present at both the La-5F and La-5FN were also deleted.
The La-5UTI also lacked oxygen equipment and, initial versions also lacked RSI-4 radio, hence the absence of radio mast and tail stub. Given the irruption of the second cockpit, the La-5UTI fuel capacity was also lower.
The La-5UTI was armed with a single 20 mm ShVAK cannon fitted into the port side on the nose, however both cannon ports and breech fairings, present on the La-5 were retained. The cannons were sighted with the standard PBP-1B sight. Any bomb-carrying equipment was also deleted. As a result the trainer variant's take-off weight was nearly identical to that of the La-5F single-seat fighter.

The La-5UTI prototype was tested at the Scientific Research Institute between 3rd and 30th September 1943 and showed performance and handling characteristics similar to those of the La-5F. 
Both the UTI prototype and initial batches were equipped with an aft-sliding rear canopy with a squared off rear frame, however in later batches the rear canopy was redesigned with the rear frame slanted to the rear, providing better visibility for the instructor in the rear cockpit. Early UTIs also lacked an external grab handle on the port side of the rear canopy, but it was fixed on every later aircraft.
The La-5UTI was powered by the same ASh-82F engine that powered the La-5F, however, when State Aircraft Factories switched production to the La-5FN, the UTIs switched also to the ASh-82FN engine, which were also equipped with the RSI-4 radio system. 
La-5UTI was manufactured from 1943 well after La-5FN production ceased at the State Aircraft Factories. Many La-5UTIs also served with La-7 equipped fighter regiments because the La-7UTI did not become operational until the spring of 1946 and, since the La-7UTI was only made in limited numbers, the La-5UTI remained as the standard trainer for both La-5 and La-7 pilots.
An unknown number of either La-5, La-5F and La-5FN were converted to La-5UTI trainers at special maintenance facilities of the VVS (Soviet Air Force). Those aircraft held most of the attributes of the the factory-built UTIs, including the original engines.  Those UTIs had also their armour removed, while some managed to keep their RSI-4 radios, albeit without radio masts with the wire running from the fin to the fuselage centreline behind the canopy. 

Sources:

1st Signal Squadron - Aircraft In Action 169 - La5-7 Fighters in Action

2nd https://en.wikipedia.org/wiki/Lavochkin_La-5