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The engine used in the first 100 (approx.) J22's was, as mentioned earlier, bought from the Germans. It was the Pratt & Whitney R-1830 Twin Wasp, or as the civilian version was called, TWC3-G Twin Wasp. The Swedish made copy, STWC3-G, was in production but only limited numbers were available as they were used for, and intended for, the SAAB B-17 and B-18 bombers.

The data on STWC-3G and the R-1830 can be found here.

As mentioned earlier, During WWII the Swedish airforce only had access the 87 octane fuel, thus they were only able to get 1050 hp (2700rpm & 42" manifold pressure) for 1 minute take off power.

Here is a list of the power settings with 87 octane fuel:

	Hp	Rpm	Man. press.	Altitude	Time limit
Take off & emergency	1050	2700	42"	0ft	1 min
Max climb and emergency power	1050	2700	40"	10,000ft	5 min
Emergency power	1015	2800	38"	above 11,500ft	15 min
Normal climb and max continuous power	850	2550	34"	0ft	No limit

Here is a list of the power settings with 100/130 octane fuel

	Hp	Rpm	Man. press.	Altitude	Time limit
Take off & emergency	1200	2700	48"	0ft	5 min
Max climb and emergency power	1050-1200	2700	40-48"	10,000ft	5 min
Emergency power	1015	2800	38"	above 11,500ft	15 min
Normal climb and max continuous power	1050	2550	42"	0ft	No limit
Cruise power	910	2550	34	1,800ft	No limit

The data on the 87 octane version is taken from SFI fpl 22 ( Special operating instructions a/c 22). The 100 octane data is extrapolated from the data of the 1200hp engine.

As you can see from the documents, the available power at altitude did not change with the higher octane fuel, it merely helped boost the low altitude power up to 5000ft.

Operation

The throttle quadrant of the J22 had 4 levers:

1. Throttle

2. Mixture

3. Propeller

4. Compressor

The power management was basically governed by a pressure sensitive aneroid that limited the boost pressure of the compressor at lower altitudes. Normal procedure was to move all levers forward until they hit the stop. The stop for the compressor varied as the altitude changed. The was a small detent for the throttle where you could apply "Combat power" for up to 5 minutes. The engine was not equipped with any secondary blowers and thus the power at altitudes above 4000m (13,000ft) suffered. If the aircraft would have been equipped with the R-1830 with a 2 stage, 2 speed compressor as the Grumman Hellcat, it would have had much better altitude performance. I will show this in the "J-22C" section.

There are indications that 1200hp was available, but I have no proof. The manifold pressure gages that I have seen in J22's all show a redline at about 107cm Hg (42").

However, only 3 out of 200 J22's still exist, and parts have been gathered from a number of sources and might not be original, or it could be the 1050Hp configuration.

At about 3500m (11,500ft) it was possible to rev the engine up to 2800rpm. Up to that altitude it was only allowed to rev the engine to 2700. This also corresponded with the peak altitude performance of the engine and thus also max speed (575km/h -357mph).

Oil cooler and air induction

The air induction intake for the carburator was on the left wing root leading edge. The (a) and (b) was the carburator air heating to prevent carburator ice build up (Ref. 11).

The oil cooler air inlet was on the right wing root leading edge (Ref. 11).

The air passed through the duct and through the cooler (c) and was vented into the engine compartment. The oil tank was situated aft of the engine and at the upper portion of the engine compartment (Ref. 11).

This picture is taken from above, showing the ducting for the carburator air inlet and the oil tank.

Cowl flaps

The cowl flaps were manually extended and retracted through a series of torque tubes. On the right upper side of the instrument panel was a crank with a blue handle which controlled the position of the cowl flaps.

It was a very simple system that required very little maintenance (Ref. 11).

Engine cowling

The engine cowling consisted of an front inlet ring (a), removable mid section panels (b and d) and removable lower panels (c) (Ref. 11). The front inlet ring was attached to the cylinders.

Here is a nice picture showing the Oil cooler inlet, cowl flaps slightly open and the mid and lower panels removed.

The powerplant was manufactured and installed as a complete unit as shown in the picture below (Ref. 18).

Powerplant

Oil cooler and air induction

Cowl flaps

Engine cowling

Send mail to hlangebro@hotmail.com with questions or comments about this web site. Last modified: January 15, 2003

Send mail to hlangebro@hotmail.com with questions or comments about this web site.
Last modified: January 15, 2003