US2101724A - Air cooled aero engine - Google Patents

Description

7- H. c. H. TOWNEND- 2,101,724

A IR COOLED'AERO EiIGI NE Filed May 12, 1936 3 Sheets-Sheet 1 1937. H. c. H. TOWNEND 2,101,72

AIR COOLED AERO ENGINE Filed May 12, 19 52 5 Sheets-Sheefi 2 H. c. H. TOWNEND AIR COOLED AERO ENGINE Dec. 7, 193

Filed May 12, 1936 5 Sheets-Sheet 3 Patented Dec. 7, 1937 UNITED STATES PATENT OFFIQE Am GOOLED AERo ENGINE Hubert Charles Henry Townend, Teddington,

England, assignor to Boulton Paul Limited, Norfolk, England 6 Claims.

More particularly, the object is to avoid the dead air region at the back of each cylinder without the use of bafile plates which are arranged'to extend near to the rear of the cylinder and restrict the opening for the air to escape, which require a considerable difference of pressure across the baflles to ensure an adequate flow of air and which therefore result in increasing the drag.

According to this invention an air deflecting member is provided comprising at least one concave surface facing the direction of flight, facing the rear surface of the cylinder, spaced apart from vthe said rear surface and located to one side of a center plane extending in the direction of flight and containing the axis of the cylinder, said, surface extending approximately between said center plane and an outer plane extending in the direction of flight and tangential tothe cylinder walls. In the case of two concave surfaces, these will be arranged one at each side of the center plane and will extend approximate- [ly between said center plane and outer planes .extendingin thedirection of flight tangential to the cylinder walls at diametrically opposite sides. In addition to the deflector, circulators maybe provided between the rear surface of the cylinder and the deflector surface and spaced apart from both. a V

The invention will be described further in detail and by way of example with reference to the accompanying drawings in which:--

Figure 1 is a view in elevation and illustrates acylinder of an aero-engine with a device in accordance with the invention arranged in the rear thereof, a

Figure 2 is a diagrammatic plan view of the arrangement on a somewhat enlarged scale,

Figure 3 is a corresponding view of an alternative arrangement, I

Figure 4 is a view partly in section of the nose portion of an aeroplane modified in accordance with the invention and'showing an engine cylinder associated with a cowling, while Figure 5 is a fragmentary view in plan generallyillustrating the manner in which the tailpiece may be arranged to form a fairing merging into the skin of the nose of the aer0plane,-

transverse to the cylinder axis have a form cor- ;tion. From the drawings it will be .seen that .allel with the direction of the motion of the air flow but diverge slightly outward from their rear -20 question forming as it were, a nose.

-invder, as the cylinder head is of larger diameter gs entry I for air may be adjusted by appropriately 7 covering 8 may be arranged over the tops of the -point or breakaway points of the air flowing passage between the cylinder wall and the circu- 55 Aircraft Fig. 6 is a side elevation of part of the aeroplane showing the complete assembly of, the en-- gine and deflecting members within the complete cowling of the aeroplane. t l

The barrel l of the cylinder is shown in Fig-- :5 ures 1 and 4 as having, as is usual, a head 2 of larger diameter than the barrel itself.

In the arrangement illustrated in these figures and in Figures 4 and 5 viewed in the direction in which it will travel when in position on an aerol0 plane there are arranged two elements 3 functioning as circulators, 'which in section on a plane responding with the distortion or elongation of the stationary vortices which will be producedbehind the cylinder of the engine when in mothey are elongated in a direction generally parto theirforward portion or extremity, the forward portion or extremity of each of the elements in In applying the invention to an air cooled cylthan the barrel, and isalso as a rule partly circular and partly irregular in shape on account of the valves, etc., the form of the circulators will, therefore, have to be modified to suit the conditions there. I

Thus the portion of the circulators immediately behind the cylinder ,head is proportionately larger than that portion thereof which is behind the barrel, and these two portions are run smoothly one into the other. In the rear of these two elements or circulators is arranged a tail piece 4 which is generally tapered or streamlined towards the rear while its forward portion is constituted'by surfaces 5 having a curvature corresponding, with the adjacent surfaces of the 40 elements 3. At each of its two opposite sides in the construction illustrated there is provided an adjustable side plate 6, and the width of the positioning the plates and thus the amount of air goingrto the backof the cylinder may be varied. As shown in Figures 1 and 4 a roof or circulators and thetailpiece. As shown in Figure 2 fins 9 may be provided on the cylinder and these will function as stabilizers for the breakway round the cylinder.

The-cooling fins on the cylinder occupy the position occupied by the nose of the circulator relative to the point of breakaway on the cylinder, the circulation will also be critical. In accordance with the invention the breakaway point or breakaway points may be stabilized by means of the small fins 9 or other obstructions, i. e. rods, attached to the cylinder or otherwise held in proximity to it, and more or less in line with'the nose or forward portion of the adjacent circulator.

By using stabilizers in this way it is found that broader air passages may be used and a greater flow of air induced through them, and that a satisfactory velocity distribution across the throat of the central duct, as measured with a small Pitot tube, may be obtained. 7

Without the stabilizers in the case of the broader passages there was found to be a tendency for most of the air to flow round one circulator only, whilst small disturbances would change it over to the other. 7

In Figure 3 the circulators are omitted and a central flat plate It] leading forwardfrom the front of the tail piece to the rear of the cylinders is provided inorder to maintain the two vortices.

In Figures 4 and 5 the tailpiece is faired into and in fact forms part of the nose ll of, the aeroplane, l2 and I3 indicating the portions of the tailpiece where they are curved to provide an unbroken surface, [4 in Figure 4 indicating the cowling associated with the engine. 7

In a twin-row radial engine, the invention would normally be applied to the rear row of cylinders only as the front cylinders are in any case usually adequately cooled, dueto the baflling action of the rear cylinders. V H

The circulators may be used as mixture preheaters, and may carry fins for this purpose.

The circulators may consist of rotating members pivoted to rotate freely by virtue ofthe circulator air flow round them or may be power driven. Their surfaces may be smooth or provided with vanes.

What I claim as my invention and desire ,to secure by Letters Patent is:-

1. The combination with an air-cooled aero engine having at least one cylinder and having a rear surface of the cylinder, said rear surface being determined relative to the direction of flight, of an air deflecting member having two concave surfaces facing the direction of flight, facing the rear surface of the cylinder, spaced apart from said rear surface and located one at each side of a center plane extending in the direction of flight and containing the axis of the cylinder, said concave surfaces extending approximately between said center plane and outer planes extending in the direction of flight and tangential to the cylinder walls at diametrically opposite sides and a forwardly extending member at each side of said air deflecting member and inclined slightly to the said outer plane and adapted to receive air flowing near the cylinder and along the said outer plane and direct it to the air deflecting member whereby it is deflected inwardly and forwardly toward the rear of the cylinder.

2. The combination with an air-cooled aero engine having at least one cylinder and having a rear surface of the cylinder, said rear surface being determined relative to the direction of flight, of an air deflecting member having a concave surface facing the direction of flight, facing the rear surface of the cylinder, spaced apart from said rear surface and located to one side of a center plane extending in the direction of flight and containing the axis of the cylinder, said surface extending approximately between said center plane and an outer plane extending in the direction of flight and tangential tothe cylinder wall, a forwardly extending member at the outer side of the said air deflecting member and inclined slightly to the said outer plane in order to receive air flowingnear the cylinder and direct it to the air deflecting member whereby it is deflected inwardly and forwardly toward the rear of the cylinder, and a cylindroid between the rear of the cylinder and the said concave surface and spaced apart from the cylinder and said concave surface, said cylindroid having a curved surface to direct said inwardly and forwardly deflected air forwardly and outwardly. b 1

3. The combination with an air-cooled aero engine having at least one cylinder and having a rear surface of the cylinder, said rear surface being determined relative to the direction of flight, of an air deflecting member having two concave surfaces facing'the direction of flight, facing the rear surface of the cylinder, spaced apart from said rear surface and located one at each side of a center plane extending in the direction of flight and containing the axis of the cylinder, said concave surfaces extending approximately between said center plane and outer planes extending in the direction of flight and tangential to the cylinder walls at diametrically opposite sides and a forwardly extending member at each side of said air deflecting member and inclined slightly to the said outer plane and adapted to receive air flowing near the cylinder and along the said outer planes and direct it to the air deflecting member whereby it is deflected inwardly and forwardly toward the rear surface of the cylinder and two cylindroids, one between the rear surface of the cylinder and each of said concave surfaces, said cylindroids being spaced apart from each other and from the cylinder and from the said concave surfaces and having a curved surface to direct said inwardly and forwardly deflected air forwardly and outwardly.

4. The combination with an aircooledaero engine having at least one cylinder and having a rear surface of the cylinder, said rear surface being determined relative to the direction ,of flight, of an air deflecting member having a concave surface facing the direction of flight, facing the rear surface of the cylinder, spaced apart from said rear surface and located to one side of a center plane extending in the direction of flight and containing the axis of the cylinder, said surface extending approximately between said center plane and an outer plane extending in the direction of flight and tangential to the cylinder wall and a forwardly extending member at the outer side of said air deflecting member inclined slightly to the said outer plane in order to receive air flowing near the cylinder along said outer plane and direct it to the air deflecting member where it is deflected inwardly and forwardly toward the rear of the cylinder and means at the rear of said air deflecting member to prevent the formation of a secondary dead air region behind said member.

5. The combination with an air-cooled areo engine having at least one cylinder and having a rear surface of the cylinder, said rear surface being deterr'ninedrelative to" the direction of flight, of an air deflecting member having a concave surface facing the direction of flight, facing the rear surface of the cylinder, spaced apart from said rear surface and locatedto one side of a center plane extending in the direction of flight and containing the axis of the cylinder, saidsurfaoe-extending approximately between said center plane and an outer plane extending in the direction of flight and tangential to the cylinder wall and a forwardly extending member at .the outer side of said air deflecting member inclined slightly to the said outer plane in order to receive air flowing near the cylinder along the said outer plane and direct itto the air deflecting member whereby it its deflected inwardly and forwardly toward the rear of the cylinder and a streamline surface extending rearwardly from the concave surface to prevent the formation of a secondary dead air region behind said member.

6. The combination with an air-cooled aero engine having at least one cylinder and having a rear surface of the cylinder, said rear surface being determined relative to the direction of flight, of anair deflecting member having two concave surfaces facing the direction of flight, facing the rear surface of the cylinder, spaced apart from said rear surface and located one at each side of a center plane extending in thedirection of flight and containing the axis of the cylinder, said concave surfaces extending approximately between said center plane and outer planes extending in the direction of flight tangential to the cylinder walls at diametrically pposite sides, a forwardly extending member at each side of said air deflecting member and inclined slightly to the said outer plane and adapted to receive air flowing near the cylinder and along the said outer plane and direct it to the air deflecting member whereby it is deflected inwardly and forwardly toward the rear of the cylinder and two cylindroids, one between each of said concave surfaces and the cylinder and spaced apart from both said concave surfaces and the cylinder, each cylindroid being elongated in a direction generally parallel to the direction of the main airflow but diverging slightly outward from its rear to its forward portion to form a nose at the forward portion to act as a circulator for the air deflected inwardly and forwardly by said concave surfaces.

HUBERT CHARLES HENRY TOWNEND.

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