US2887731A - Observatory having suction means to reduce convection currents - Google Patents

Description

May 26, 1959 H. c. WAALE 8 I OBSERVATORY-HAVING SUCTION MEANS TO REDUCE CONNECTION CURRENTS Filed June 13, 1956 5 Sheets-Sheet l llllllll Ill 60D aw on m v Y3. lllflnmmuumunumnmnumnn VB w wl 8 6w 6 46E a a.

May 26, 1959 H. c. WAALE OBSERVATORY HAVING SUCTION MEANS TO REDUCE CONNECTION CURRENTS 5 Sheets-Sheet 2 Filed June 13, 1956 May 26, 1959 5 Shets-Sheet 5 Filed June 13, 1956 Y 9 H. c. WAALE' 2,887,731

OBSERVATORY HAVING SUCTION MEANS TO REDUCE CONNECTION CURRENTS Filed June 13, 1956 5 Sheets-Sheet 4 I May 26, 1959 Filgd June 13, 1956 v H. C. WAALE v OBSERVATORY HAVING SUCTION MEANS TO REDUCE CONNECTION CURRENTS 5 ShetQShqet s United States Patent OBSERVATORY HAVING SUCTION MEANS TO REDUCE CONVECTION CURRENTS Hans C. Waale, San Bernardino, Calif.

Application June 13, 1956, Serial No. 591,242

11 Claims. (Cl. 20-1) Brief summary of the invention This invention relates to the improvement in seeing in telescopes and observatories by the removal by a continuous application of suction of convection currents arising from the parts of a telescope, the observatory structure, and the grounds of the observatory site.

This invention also relates to the improvement in seeing in observatories by the removal by suction of convection currents which have arisen from adjacent areas and drifted over the observatory site.

It is the object of this invention to remove all convection currents that may arise or fall away from the parts of the telescope, or the observatory structure or nearby land areas, in the most direct manner, with the aim of producing a minimum of turbulence in the area traversed by the light beam.

In the drawings Fig. l is a side view showing a convection current arising from a part of a telescope and extending across the area traversed by the light beam. Fig. 2 shows the principle of the removal of convection currents by a continuous application of suction to hollows which are connected to openings at the exterior surfaces of parts of a telescope or observatory. Fig. 3 shows the principle of the removal of convection currents from a solid part of a telescope or observatory by a continuous application of suction to an air space between the part and a stretched cloth covering. Fig. 4 is a perspective view of a telescope member having a layer of cork insulation cemented to its exterior surface. Fig. 5 is a perspective view of a fragment of a telescope member having cemented cork insulation and the application of a cloth covering with an air space between the covering and the insulated surface of the part. Fig. 6 is an exploded view of a cloth fastening device (and spacer) used for round surfaces. Fig. 7 is an enlarged cross section of a stud assembly of Fig. 6. Fig. 8 is a cross section of stud assembly of Fig. 9. Fig. 9 is a side view of a cloth fastening device (and spacer) for flat surfaces. Fig. 10 is a perspective view of an open tube type reflecting telescope and part of the interior of an observatory, which are designed according to this invention. Fig. 11 is a diagram showing air passages in relation to an observatory designed according to this invention. Fig. 12 is an exterior view of anobservatory with air passages according to the principles illustrated in Fig. 11. Fig. 13 is a diagram of a plan view, of an observatory site, showing positions of air passages surrounding an observatory and the locations of openings connecting said passages to the outside air which are according to this invention. Fig. 14 is a vertical cross section of an observatory site having the principles of Fig. 13 adapted to a hill side location.

Detailed description Referring to Fig. 1, the convection current 64 of air expanded by latent heat emitted from part 63 rises up- Wards and crosses the area traversed by the light beam 60 (which is from the object being observed in the telescope) where its air of variable temperatures causes interferences by its variable index of refraction. Fig. 2 shows the principle of drawing air through the openings 23 into the hollows 20, convection currents 64 are thus prevented from forming. The variably heated air surrounding the parts is removed inwardly, and prevented from crossing the area traversed by the light beam 60. Fig. 3 shows the principle of causing air to be drawn through a cloth covering 24 into a space 62 between the cloth covering 24 and the solid part 65 of a telescope or observatory. The cloth covering 24 supplying a uni form distribution of small orifices, is light in weight, and the space 62 for the withdrawal of air is quite readily formed. Convection currents are prevented from passing throughthe cloth covering 24 by the incoming circulation of air. The methods of Figures 2 and 3 by reason of the directness of their action requires a minimum amount of air to be drawn for the removal of convection currents as described. The methods can also remove convection currents in a direction that gives fullest clearance for the optical functions.

All parts of the telescope which have exterior surfaces are as far as possible, made of hollow construction as shown in Figures 4, 5 and 10, the hollows 20 are continuously connected together at the junctions 21 of the parts as shown in Fig. 10 (and leaving no exterior openings except the one at the lower polar axis 22, Figs. 10 and 11, and holes 23 in Fig. 4) so that when suction is applied at the lower end of the polar axis 22, it will be freely transmitted to hollows 20 of all the parts. The holes 23, Fig. 4, connecting the inner hollows 20 of the parts to their exterior surfaces 26 in a regular pattern, cause a uniform distribution of suction over the exterior surface of the parts, forming a system of drawing inwardly (away from the light beam 60 in Fig. 2) of all convection currents emitted from the parts. The addition of a thin continuous coat of insulation 27 cemented or otherwise closely fastened to the exterior surface 26 of the parts, covering all but the holes 23, decreases the rate of the ordinary conduction and radiation from the parts to the outside air, and less circulation of the kind illustrated in Fig. 2, will hold back their emitted convection currents, the decreased amount of circulation required causing less turbulence resulting in the area traversed by the light beam 60 in Fig. 2 and giving less cause for noise or vibration. The application of a continuous cloth covering 24 (which offers resistance to, but does not entirely block the passage of air) over the insulated surface 27 of the parts, and with an air space 25 between (using fastening devices in Figures 6 and 7) causes an increased uniformity in the distribution of suction over each part, through the equalization of pressure in the space 25. The cloth covering also acts as a shield against radiation from. the parts to the outside air. Convection currents arising from the insulated surface 27 will be repelled inwardly by the circulation through the cloth covering 24 and forced to move within the space 25 to the holes 23 and into the hollows 28.

Fig. 10 illustrates a telescope that has been constructed according to this invention with the continuous cloth covering 24 in Fig. 5 applied over its entire exterior surface. All parts have surfaces similar to the detail shown in Fig. 5 except for modifications necessary to change from round to fiat surfaces (in which the cloth fastening device for flat surfaces in Figures 8 and 9 is used). Fig. 10 at No. 3 shows one of a continuous circle of ports that are situated around the outside edge of the optical surface 28 of a mirror or speculum 61. During observation, a comparatively strong suction is continuously applied to the ports 3, to cause a uniform downdraught to strike against the mirror 5 optical surface 28 and drive away the convection currents that arise from it by the shortest route, which is toward the ports 3.

Fastening devices.ln Figs. 6-9 cloth fastening devices are illustrated; these are designed to fasten the cloth covering 24 to the parts of the telescope with the space 25 between the cloth covering 24 and the exterior surface 26 of the telescope parts. For a cylindrical telescope part, the spokes 48 Fig. 7 are welded 31 in vertical position in respect to the exterior surface of said part. The spokes 48 are uniformly spaced about the exterior circumference of a right angle cross section of the cylindrical part, and the outer ends of the spokes 48 are welded to the circular rod 50forming a wheel like structure with the center line of the cylindrical part as an axis. The described structure is repeated at uniform intervals measured axially in regard to the cylindrical part. The cloth covering 24 is stretched over and between the circular rods 50. The hoops 51 are next clamped around the periphery of the circular rods 50 with the cloth covering 24 being securely held between the circular rods 50 and the hoops 51. In Figs. 8-9 are illustrated cloth fastening devices for a telescope or observatory part which has a fiat exterior surface. The spokes 47 (assembled with the burrs 56 and the lower s'lats 54) are welded 31 in vertical position to said surface forming laterally spaced rows of spokes 47, with each row of spokes 47 supporting a lower slat 54, the cloth covering 24 is then stretched over and between the slats 54. The upper slats 53 are next placed lengthwise against the lower slats 54 as shown in Figs. 89. The burrs 52 are then tightened against the upper slats 53, the cloth covering 24 will then be firmly held between the upper slats 53 and lower slats 54.

Observat0ry.In the interior of the revolving dome 70, Fig. 12 (excluding the area occupied by its observation window 71 in Fig. 14) using the fastening device of Figures 8 and 9, which are welded 31 in Fig. 9 at regular distances on the inner surfaces of the arch spans 34 in Fig. 10, a continuous covering of cloth 24 is uniformly stretched and fastened forming a continuous inner lining to the dome, with an air space 62 in Fig. 11 between it and the outer sheathing 65, the space 62 containing all the frame work to which the sheathing 65 is fastened. The dome being made otherwise air tight around the space 62 by its construction, except at the row of ports 44 which are made through sheathing 65 and encircling the dome near its lower outside edge 36. During observation, suction is continuously applied to the ports 44. The interior space 62 containing open frame work 34, offers a large passage where air can move with small resistance and hence with small changes in pressure. The nearly equalized pressure resulting would produce a fairly uniform distribution of suction over the interior surface of the cloth inner lining 24, and which distribution could be made still more uniform by a cloth lining that is progressively of a tighter weave as it approaches ports 44. With this arrangement, convection currents emitted from the interior surface of the dome can be repelled by the resulting uniform circulation through the cloth 24 in Fig. 11, and forced to move within the space 62 to the ports 44 and the connected passages 5, 7, 8 and 9. An entirely similar arrangement would produce the same effect in regard to the circular wall 38 in Fig. 10, upon which the dome is supported; its construction as far as is necessary for the kind of circulation described for the dome is, or can be quite similar. The suction being applied to a row of ports 39 in Fig. 11, which extend all around the cylindrical wall near its lower outside edge 35. The ports 39 are made through the sheathing 41. Suction when applied to the ports 39, passes through the space 68 to the cloth covering 24. The resulting uniform circulation through the cloth covering 24 causes convection currents emitted from the inner surface of the sheath- 4 ing 41, to be forced to move within the space 68 to the ports 39 and the connected passages 8 and 9.

Insulati0n.-The application of a coat of insulation 37 in Fig. 11 fastened tightly to the interior surface of the sheating 65 of the dome would decrease the rate of the conduction and radiation from the sheathing 65 into space 62, and less circulation as described for the interior of the dome, will hold back the convection currents emitted from the sheathing 65. Similarly the application of a coat of insulation 37 in Fig. 11 to the inner surface of the sheathing 41 of the circular wall, would decrease the rate of the conduction and radiation from the sheathing 41, and less circulation of the kind described for the circular wall 38 in Fig. 10 would hold back the convection currents emitted from the sheathing 41 (the descreased amount of circulation required in both cases, causing less turbulence resulting in the area traversed by the light beam 60) Outside of dame 70 in Fig. 12.-All air drawn in by the suctions applied as described for the interior of the observatory, should most favorably come from above the observatory where the air would be less variable in temperature than that which is nearer to the ground, but the air drawn in from above the observatory should not be mixed with convection currents arising from the exterior surface of the observatory structure. Convection currents arising from the exterior surface of the dome are drawn downward by producing a general down-draught over the dome by a continuous application of suction to ports 6 in Fig. 11, which are located at regular intervals on the upper side of the manifold 5 in Figures 11 and 12, which encircles the dome near its lower outside edge 36. Convection currents arising from the outside of the sheathing 41 in Fig. 11, of the wall 38 are drawn in as they pass upward near the manifold 5. Thus the air drawn in from above the observatory through the observatory window 71 in- Fig. 14 will not meet rising currents of air carrying convection currents from the outside of the observatory structure. As the suction applied to ports 6 must necessarily be quite strong, when the telescope is set at low altitudes the ports 6 which are directly underneath may be shut down somewhat by electric controls, if they seem to be causing interferences.

The manifold 5 in Figures 11 and 12 has a loose swivel connection 40 to the dome 76 (above and below the row of ports 44). The manifold 5 is supported by vertical cylinders 7 which supply a passageway for the air drawn into the manifold 5 (by the suctions applied as described at ports 6 and 44) to the interior of the circular distribution passage 8.

The interior space 68 in Fig. 11 is connected to the passageway 8 at the ports 39. A passage to the lower polar axis 22 also is connected to the passageway 8 at 42. A wind tunnel 9 also is connected to the passageway 8, carrying all air drawn in by the suctions (both within the observatory and that applied around the outside of its dome) to a gate in the distance 14 in Fig. 14.

In Fig. 11 a fan 55 is indicated with its driving motor 49. These are located in the wind tunnel 9 to supply motive power for the suction described for the interior and exterior of the observatory.

Observatory site Figures 13 and 14.-Convection currents arising from the grounds of the observatory site can cause interferences in the field of vision when the telescope 12 is set at comparatively low angles, and convection currents from this area can also be carried over the observatory structure by a light breeze and produce the same interferences. To remove convection currents arising from the grounds of the observatory site, and to prevent them from being thus carried about by light breezes, suction is continuously applied during observation to a uniform arrangement of ports 11, in Figures 13 and 14 which are situated with spaces between over the entire ground surface 18, of the observatory site and are connected to large stream-lined, circular underground channels 10. The channels are in turn connected to wind tunnels 9 leading in four directions from the observatory. In each of the wind-tunnels 9, Fig. 14, are fans 17 driven by motors 30 which are housed in the rooms 45 and con nected to the fans 17 by the transmission shafts 19 which pass through the connecting tunnels 46. The fans 17 add motive power to produce the suction applied as described both for the observatory and for its adjacent land area.

The wind tunnels 9 are controlled by gates 13, 14, 1S and 16, in the discharge terminals 32, which are opened only when they are in positions 'that are down-wind 17 from the observatory, as illustrated at gate 14 with gates 13 and 15 shown in closed position. The air thus drawn in at the ports 11, is forced to issue into the atmosphere through gate 14, which is at a suflicient distance downwind 17 that said air will not likely be drifted back over the observatory, nor the turbulence of its reissue into the atmosphere, extend backwards to the field of vision in the telescope 12. Suction can be applied at such strength at the ports 11 so that warmed air containing convection currents that have arisen from grounds 80 adjacent to the observatory site Fig. 14, and have been brought over said side by light breezes could be largely drawn in by the suction at ports 11, and caused to by-pass the observatory in the channels 10. Obviously the effectiveness of such construction would increase with its size, and be largely limited by the amount of appropriations and engineering skill.

What is claimed:

1. In the construction of an observatory, an exterior sheathing, an interior lining and an air space defined between said lining and said sheathing, said lining composed of thin material having small orifices passable by air, a means of producing continuous suction in said air space, whereby said suction may be transmitted through said air space and said orifices, respectively, and cause air adjacent the exterior surface of said lining, to be continuously drawn through said lining to remove convection currents containing heat emitted from said sheathing.

2. In the construction of an observatory, frame parts, an exterior sheathing, said sheathing attached to said frame parts, an interior lining and an air space between said lining and said sheathing, said frame parts having portions within said air space, said lining composed of thin material having small orifices passable by air, a means of producing continuous suction in said air space, whereby said suction may be transmitted through said air space and said orifices, respectively, and cause air adjacent the exterior surface of said lining to be continuously drawn through said lining to remove convection currents containing latent heat emitted from said sheathing and said portions.

3. In the construction of an observatory, an exterior sheathing, a layer of insulation attached to the interior surface of said sheathing to reduce the flow of heat to or from said surface, an interior lining and an air space between said lining and said sheathing, said lining composed of thin material having small orifices passable by air, a

means of producing continuous suction in said air space,

whereby said suction may be transmitted through said air space and said orifices, respectively, and cause air adjacent the exterior surface of said lining to be continuously drawn through said lining to remove convection currents which contain or have lost said heat which has penetrated said insulation.

4. In the construction of an observatory, a dome, an annular passageway surrounding said dome in radially spaced relation having annularly spaced exterior openings, a means of producing continuous suction in said openings whereby air may be continuously drawn into said openings and cause a down-draught over said dome to remove convection currents containing heat emitted from the dome.

, 5. In a construction adjacent to an observatory, an annular passageway surrounding said observatory in radially spaced relation and having annularly spaced exterior openings, a means of producing continuous suction in said openings whereby air may be continuously drawn into said openings, and carried away through said passageway to the extent of causing a down-draught over said observatory to remove convection currents containing heat emitted from said observatory.

6. In a construction adjacent to an observatory, a passageway having an annular opening, said opening encompassing said observatory, a means of producing continuous suction in said opening whereby air may be continuously drawn into said opening and carried away by said passageway to the extent of causing a down-draught over said observatory to remove convection currents containing heat emitted from said observatory.

7. In a construction adjacent to an observatory, a passageway having openings annularly spaced adjacent the exterior periphery of said observatory, a means of producing continuous suction in said openings, whereby air will be continuously drawn into said openings and carried away by said passageway to the extent of causing a downdraught over said observatory to remove convection currents containing heat emitted from said observatory.

8. In a construction in a land area adjacent to an observatory, passages for the flow of air having exterior openings in laterally spaced relation to the exterior surface of said land area, a means of producing continuous suction in said openings, whereby air may be continuously drawn into said openings and removed through said passages to the extent of causing a down-draught over said land area to remove convection currents containing heat emitted from said land area.

9. In the construction of an observatory, a part, an exterior covering, and an air space defined between said covering and said part, said covering having openings passable by air, a means of producing continuous suction in said air space, whereby said suction may be transmitted through said space and said openings respectively and cause air adjacent the exterior surface of said covering to be continuously drawn through said openings to remove convection currents containing heat emitted from said part.

10. In a construction in a land area adjacent to an observatory, an observatory, passages for the flow of air having exterior openings in laterally spaced relation to said land area, a means of producing continuous suction in said openings, whereby air adjacent the exterior surface of said land area may be continuously drawn into said openings and removed through said passages to remove convection currents containing heat emitted from said land area.

11. In the construction of an observatory, an exterior sheathing having openings in laterally spaced relation to the exterior surface of said sheathing, a means of producing continuous suction in said openings whereby air adjacent said surface may be continuously drawn through said openings to remove convection currents containing heat emitted from said surface.

References Cited in the file of this patent UNITED STATES PATENTS 416,364 Hough et a1. Dec. 3, 1889 1,916,908 Stacey et al July 4, 1933 2,071,093 Van Horne Feb. 16, 1937 2,107,812 Berry et a1 Feb. 8, 1938 2,152,394 Veeder Mar. 28, 1939 2,212,346 Kroon Aug. 20, 1940 2,326,552 Morse Aug. 10, 1943

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