"Cirrus Aero Engines Ltd." allied with ADC for the production of aero engines.

"Cirrus Hermes"

-"American Cirrus" was founded as well, to manufacture Cirrus engines in the USA at the NY facilities. The Cirrus Hermes IIB gave 115 hp while the Cirrus Hermes I gave only 105 hp.

"Cirrus Hermes I"

-Historically Cirrus was founded by Major Frank B. Halford in 1924 to build aviation engines.

-Frank came from the ADC (Air Disposal Company, also known as Airdisco). After improving the Renault V8, as we know, the company was taken over by Hermes Eng. Co. to improve the Cirrus as Hermes I with 105 hp and Hermes III with 85/90 hp. In the year 1928.

-Cirrus Hermes Co. was located at the Croydon Aerodrome in Surrey. All its engines are light and have four cylinders.

-The Cirrus-Hermes II gave 110/120 hp.

"Cirrus Hermes II"

-The picture below shows the fully enclosed 110/115 hp Cirrus-Hermes.

"Cirrus Hermes 110/115 hp"

-Interestingly, the IIB version was the same Hermes II engine but with inverted cylinders and only 105/115 hp.

-The Cirrus-Hermes II and IV reached 120 and 140 HP depending on the variant.

"Cirrus-Hermes III"

-The less powerful III already had the different lower crankcase, breaking the line of its predecessors.

-The IV shown below has definitely inverted cylinders, a design that would continue in the brand's following engines.

"Cirrus Hermes IV"

-In 1934, Cirrus Hermes passed to Blackburn Eng. and General Aircraft Ltd. (see), as the Cirrus Eng. Division.

-Then they produced  the inverted 4-cylinder Cirrus Minor that gave 80 to 100 hp according to the I or II series.

"Cirrus Minor I"

"Cirrus Minor II"

-In 1935 there are the Cirrus Major engines, first with 120/130 hp and after that the II and III series giving 138/158 hp, with a displacement of 6.3 l.

"Cirrus Major"

-The Cirrus 702 model, had a magnesium alloy crankcase, and injection into the cylinders, giving 180 hp.

-Below are some Cirrus-engine advertisements that appeared between 1929 and 1953. Some mentioning records obtained by each of the brand's models.

"1933"

"1936"

 
"1943"

"Cirrus Bombardier 1953"

-We located an illustration of a Cirrus Hermes Mark IIB (or 2B).

-With four inverted cylinders giving 115 hp at 2,000 rpm. See Cirrus / Hermes.

"Cirrus Hermes Mark IIB"

-The Cirrus Minor that delivered 120/130 hp.

"Cirrus Minor"

-The Major is already shown in the main text but now we have picture with an almost frontal view.

-This engine delivers about 135 hp.

-There was also the Major 150 hp version, as shown below.

"Major de 135 HP"

"Major de 150 HP"

"Cirrus logo"

-We obtained more complete and clearer photographs for the Cirrus-Hermes 105-115 hp.

"Cirrus-Hermes, left side view"

"Same engine, front and rear view"

-It is interesting to see the indicator at the lowest part of the oil pan.

"Cirrus-Hermes, right side view"

"Cirrus-Hermes logo"

From appendix 6. The Midget model was an inverted four-cylinder engine that gave 49 hp at 2,300 rpm reaching 55 hp at 2,600 rpm.

“Cirrus Midget”

"Cirrus Midget, side view"

-The Midget was presented at the 1938 Paris Air Show.

-The Cirrus-Hermes III engine was used in sports aviation and raid flights, giving considerable results. See main text.

“Cirrus Grenadier viewed from both sides”

-The Grenadier gave 300 hp at 2,500 rpm on takeoff.

-At 8000 feet with 2,400 rpm at cruising power it gave 236 hp.

In addition, as modernity it had the camshaft on the cylinder head (today this would be called OHC) and had fuel injection system.

"Rear view with supercharger"

As mentioned in the main text, it did not go into production and it was a coincidence to find these photographs. A happy coincidence.

"Cirrus Hermes on an AVRO"

-In the Shuttleworth collection there is an Avro with a perfectly restored Cirrus-Hermes engine.

-The engine from 1927 that gives 105 hp looks authentic although the airplane is a replica.

-We are struck by the arrangement of the two magnetos on the right side and much on the rear, leaving one of the magnetos in cantilever. A unique disposition in all existing aviation engines.