The Wallace & Tiernan company started out making water chlorination (Wiki) equipment invented by Charles Frederick Wallace based on using Chlorine gas. Part of that was the need to have a gas pressure gauge that operated with small negative pressures, so conventional barometers and altimeters were not suitable so they invented ones that would work. One aspect was to enclose the Aneroid barometer (Wiki) movement in a box and provide a fitting on the box as well as a fitting on the bellows (Wiki) so that differential pressures could be measured. The other improvement was to make the barometer more sensitive so it could measure the low pressures involved.
The resulting meter turns out to be a very good barometer/altimeter these were purchased by various surveying outfits, typically for government topographic surveying since they cost more than the typical barometer/altimeter. The FAA also specified them for, I'm guessing, use at airports to measure the barometric pressure so pilots can set the runway pressure in their altimeters (Wiki), so that the published elevation matches the runway surface.
In addition to the gas pressure meters made for barometer/altimeter applications they also made versions for all kinds of gas pressure applications, both absolute, gauge and differential. One of the features is that the pointer can move more than 360 degrees by means of an index that signifies which range the pointer is one. Most have two ranges with a total angle a little less than 720 degrees, but that are some that have maybe 5 turns of the pointer.
Wallace & Tiernan company also made Radiosonde equipment used as part of weather data.. The key piece would be the altimeter mechanism that goes aloft, but also the ground equipment to demodulate the data from the sensors.
Barometers (Wiki) measure the pressure of the air column above the instrument.
Aneroid type with a range of 26.0 to 31.5 inches of Mercury with minor tick marks of 0.02" Hg, i.e. readable to 0.01" Hg. The pointer moves less than one turn.
These (Wiki) are just barometers calibrated to read altitude. "The calibration of an altimeter follows the equation
c is a constant,
T is the absolute temperature,
P is the pressure at altitude z, and
Po is the pressure at sea level.
The constant c depends on the acceleration of gravity and the molar mass of the air. However, one must be aware that this type of altimeter relies on "density altitude" (Wiki) and its readings can vary by hundreds of feet owing to a sudden change in air pressure, such as from a cold front, without any actual change in altitude."
The density altitude (Wiki) can be measured directly, for example see 4263804 Apparatus for directly measuring density altitude in an aircraft, Robert A. Seemann, 1981-04-28 - which works by measuring the power consumed by a motor turning a paddle wheel.
When the lid is closed and the rubber stopper-slide on the lid is in the Vent closed position then the vent is closed, otherwise the vent is opened. It should be closed whenever a measurement is not being made to keep moisture out of the chamber.
Unscrew the lid and, while looking where the pointer is going to be, quickly open the lid. You can see the pointer move tens of feet. So far it's always been between 16 and 18 (1600 - 1800 feet dial, or 600 to 800 feet actual) and always there is movement.
This particular unit is marked "Hundred Feet" so when the pointer is at 17 the indicated altitude is 1700 feet. But . . . it is also marked "Zero Equals - 1000 ft. per S.M. Table S1" so you need to subtract 1000 feet from the dial to get the actual reading. So in this case 1700 - 1000 = 700 feet elevation. That allows for elevations up to 1000 feet below sea level to be measured.
The displayed range is 0 to 3500 to 7000 feet with an elevation range of -1000 to 2500 to 6000 feet above sea level.
Now that it's clear how to read the dial [ (100 * dial) - 1000 = elevation in feet] the next step is to calibrate it. Maybe the runway elevation at the local airport would be good for that.
FA Model NumbersW&T data sheet 610.100 lists the following (i.e. they are closely related). All have 6" dials and weight between 3 and 4 pounds. Standard dial calibration units are inches of Hg.
FA-112 FA-139 FA-160 FA-185
13 to 30.5" Hg FA-112160
22 to 31.5" Hg FA-112150
19 to 32" Hg FA-112170
28 to 31" Hg FA-139220
Altimeter Setting Indicator
660 to 800mm Hg FA-160180
or 26 to 31.5" Hg FA-160420
22 to 31.5" Hg FA-185260
13 to 30.5" Hg FA-185300
0.1% of full scale
0.3% of full scale 0.33% of full scale 0.1% of full scale Sensitivity
0.01% of full scale 0.02% of full scale 0.2% of full scale 0.01% of full scale Scale Length
2 pointer revolutions
1 pointer revolution
1 pointer revolutions
2 pointer revolutions
FA160 0 to 2.0 inches Hg
FA160 0 to 120 inches Hg
FA160 0 to 40 inches Hg
FA160 0 to 800 mm Hg
FA160 RR12158 0 to 100 mm Hg abs
FA160 13,000 to -1500 feet 8.5" dial
FA185 0 to 3,500 to 7,000 feet 5"? dial
From booklet Altimetry Manual and Operating Instructions for W & T Surveying Altimeters, Instruction Book No. FIA-112-1-3, 1953.
The types FA-112, FA-181 and FA-185 all have the same mechanism, and dials approximately 5" in diameter. The scale is about 29" long over almost two revolutions. Reference is made to the Smithsonian Meteorological Table (SMT) 51 in regard to the Zero equals 1000 feet notice?
The FA-176 is a more sensitive instrument having a narrow range of -500 to 1500 feet per SMT 51 (-150 to 500 meters) with graduations of 5 feet.
FA176 19 to 21.5 to 24 Pounds 8" glass portable 11-3/8" overall dia
The FA-181 is a military model with it's round aluminum case also serving also as the carrying case. The lid may be removed for wall mounting the instrument. (two "_" screws hold the lid on).
FA181 0 to 3,700 to 7,000 feet 4"? dial
FA181 0 to 550 to 1,200 meters (zero = -300 meters), portable
The FA-185 has a round aluminum case with no lid. The leather carrying case with hinged lit is provided.
In the FA-112 the window closure is dust tight but not air tight.
Each dial is individually calibrated for its particular mechanism. Each dial and mechanism is marked with a serial number and they are not interchangeable.
From a sampling of eBay ads.
FA129 0 to 400 to 800 mm Hg 8-1/2" dial
FA129 0 to 400 to 800 mm Hg 8-1/2" dial
FA129 0 to 16.5 to 32 PSI 10-3/4" flange
FA129 0 to 50 to 100 inches Hg absolute 10-3/4" flange
FA129-MM15679 0 to 36 to 70 Abs cabin pressure PSIG
FA141 Liquid Oxygen ?
FA141 0 to 20 inches H2O
FA141 0 to 10 inches H2O 8-1/2" dial
FA141 0 to 800 mm Hg
FA141 0 to 800 mm Hg
FA141 0 to 800 mm Hg
FA141 0 to 500 PSI Liquid Oxygen
FA141 0 to 10 PSI
FA141 MM11336 0 to 20 inches H2O 3-3/4" flange
FA141 0 to 20 inches H2O vacuum
FA145 0 to 90 to 300 inches Hg
FA145 0 to 490 to 1,000 mm Hg
FA145 0 to 1,900 to 5,000 #/sq ft
FA145 -30 to +40 to +170 inches Hg
FA145 -100 to +10 to +2,400 inches H2O
FA145-NNI5600 3 to 15 PSIG (0 to 100 %) 10-3/4" flange
FA145 0 to 6.5 to 15.0 PSIG N2
FA145 0 to 54 to 120 inches H2O
FA145- MM19248 0 to 5.0 to 10.0 PSI
FA145-MM11329 -100 to 10 to 24 inches H2O 10-3/4" flange
FA145-NN15924 0 to 20 inches H2O 8-1/2" flange
FA145-MM13503 0 to 46 to 90 inches Hg
FA-145 Calibrator 0 to 215 to 430 inches H2O small box with controls
FA145-MM13503 0 to 46 to 90 inches Hg
FA145-CC12151 o to 18 to 35 PSI
FA149 Monostat Pressure Regulator - hand wheel at top sets pressure/vacuum
FA149 Monostat Pressure Regulator - hand wheel at top
FA193 no pointer, just electrical switch (5 mm Hg) box options: Barometer, Altimeter, Contactor (checked), Pneumatic Calibrator, Monostat
FA199 0 to 1400 to 2550 to 3600 to 4800 meters altitude, portable (4 turns, unlike others which are 1 or 2 turns)
FA233 0 to 100 to 200 PSI
FA234-PP16919 0 to 150 to 300 PSIG
FA-234-PP14681 0 to 150 to 300 PSIG 10-3/4" flange
FA181000 0 to 1,000 to 2,100 meters
FA193111 no pointer, just electrical switch 11746 mm ?
FA193161 no pointer, just electrical switch
FA-193121 no pointer, just electrical switch, NSN 5930-806-5756
65-120 Pneumatic Calibrator -23 to 14 to 30.6 inches H2O
65-125 like the 65-120 except digital pressure gauge
Fig 1 Case Closed
Fig 2 Case Open
Fig 3 Door open showing screwdriver & Sling Psychrometer
Fig 4 Back with hanging "d" hole.
Should be read with dial/back vertical, not laying on table.
Fig 5 Sling Psychrometer (Wiki)
Fig 7 Compare to Kestrel 5500FW
Fig 8 Corrections imply accuracy to better than 5 feet.
Top: convert altitude to pressure
Center: Air Temp & Relative Humidity corrections
Bottom: Custom temperature correction for this particular instrument.
((100* 16.5)-1000) = 650'
Fig 10 Altitude variation from Kestrel 5500FW
550' to 980' variation due to weather.
I don't have a feel for how much to expect.
Fig 11 Two screws at left to remove lid for wall mounting.
Bottom center desiccant access hole.
"Caution, Close Breather Tube, for Storage or Transport"
A note on patent datesWhen something that might be of use to an enemy in time of war the patent publication is delayed. My guess is that the amount of delay is proportional to how big a secret it is. When you see two dates, such as 1941-09-24 (Pub: 1945-02-06) it means the patent was filed in 1941, just prior to W.W.II for the US, but only published near the end of W.W.II. In other cases I've seen delays of 20 to 30 years, for example see China Lake Patents.
2603973 Flexible chamber pressure gauge, Charles F Wallace, Wallace and Tierman Inc, 1947-03-15 (Pub: 1952-07-22) - 2 fittings & other improvements
Wallace and Tierman
Wallace and Tierman have about 647 patents, so not all of them are here. AFAICT (Wiki) the company started out making water chlorination equipment and beacon lights for marine and airports where reliability was very important. The water chlorination system that uses Chlorine gas requires precision measurement of small negative pressures necessitating the invention of an improved gas pressure gauge. They also got into process equipment relating to products based on Chlorine, probably because it's a toxic gas and proper handling was one of their skill sets. They are now part of a company that does water treatment but does not seem to make barometers or altimeters. http://www.evoqua.com/en/brands/Wallace_and_Tiernan
The inventor is listed as C.F. Wallace on most of these patents which makes me think he was not really the inventor but rather the president of the company. I can understand how he may have made the initial inventions but don't see how he could have made inventions is such different subjects.1553294 Shortening compound, John C Baker, Wallace and Tierman Inc, 1921-09-02 - for pie crust: fat, water, Sodium stearate & stearic acid emulsed at 3,000 PSI.
1587050 Electrical indicator, Harry L Tanner, 1922-04-13 - zero center bi-polar indication, not full circle
1593109Chemical dosing apparatus, Charles F Wallace, Wallace and Tierman Inc, 1924-03-06 - water chlorination
1678625 Apparatus for the therapeutic application of chlorine,
Charles F Wallace, John C Baker, Wallace and Tierman Inc, 1924-06-18 - diluting Chlorine gas in air for respiratory therapy.
1741590 Electrical indicating instrument, Harry L Tanner, Tanner Engineering Co, 1926-04-26 - an early 3-wire synchro?
Charles F Wallace, John C Baker, Wallace and Tierman Inc, 1926-06-08 - for comparing color of liquids.; 2341810;
1834759 Rubber printing plate, John C Baker, Wallace and Tierman Inc, 1928-03-24 - improvement made with backing plate in the same step
1841341 Means for producing indications, H.L. Tanner, 1923-11-17 - electrical meter movement, soft iron vane on bottom of needle pulled to bipolar electromagnet.
1850975 Method of making hypochlorite solutions, John C Baker, Wallace and Tierman Inc, 1927-04-11 - a method of making hypochlorite (Wiki) solutions
1878076 Electrically energized motor, Charles F Wallace, Wallace and Tierman Inc, 1929-03-07 - The Self Winding Clock Co. was doing this in 1877
1955616 Signal device, Charles F Wallace, Wallace and Tierman (sic) Inc, 1927-08-29 - Marine or Aircraft Fresnel Signal light with 6 lamps to come into place as the active lamp burns out; 2051506; 2289315; 2342085; 2551029; 2551028; on eBay listed with key words: Wallace Tiernan 24 inch ship boat light (the cylinder is about 8" dia.)
you can see the top of the wheel of lamp bulbs.
1964227 Telemetric system, H.L. Tanner, Wallace and Tierman Inc, 1928-05-26 - an early 3-wire synchro?
1986308 Weighing apparatus, Charles F Wallace, Wallace and Tierman Inc, 1928-12-14 - circular paper disk records weight vs. time
2016257 Process of manufacturing n-chloro-azo-dicarbonamidines,
Franz C Schmelkes, Henry C Marks, 1934-03-17 -Bactericide (Wiki)
2022747 Incandescent lamp,
Sovulewski Lawrence Gabriel, Booth George Martin, 1934-07-06 - filament is vertical line for use in Fresnel lens (Wiki) systems
2233372 Method for testing dough, John C Baker, Wallace and Tierman Inc, 1938-05-21 -
2306819 Sound signal apparatus, John R Mackay, Wallace and Tierman Inc, 1938-03-14 - electromagnetically driven fog horn: GB526250;
2340279 Recorder, Charles F Wallace, Wallace and Tierman Inc, 1940-12-26 (Pub: 1944-01-25) - time interval type to work with Radiosonde; 2354086;
2347160 Radiometeorograph transmitting apparatus, Charles F Wallace, Wallace and Tierman Inc, 1940-04-04 (pub: 1944-04-18) - Radiosonde; 2340718; 2352578;
2347345 Radiometeorograph transmitting apparatus, Wallace Charles F, Wallace & Tiernan Inc, Apr 25, 1944, 340/870.1, 340/870.12, 340/870.16, 188/185, 200/56.00R, 340/870.13, 73/170.28 - Temperature, pressure, relative humidity
2361723 Pressure-responsive meter apparatus, Charles F Wallace, Wallace and Tierman Inc, 1940-01-31 -"This invention relates to detecting, recording and indicating means and procedure, notably of pressure-responsive type, and designed, for example, to detect and record gas flows handled under small pressures, particularly small negative pressures." For water chlorination system.
2368905 Aneroid barometer movement, Wallace Charles Frederick, Wallace and Tierman Inc, 1941-09-24 (Pub: 1945-02-06) - maybe for use in Radiosonde?
2418379 Apparatus for establishing a vacuum in manometer-type instruments, Charles F Wallace, Wallace and Tierman Inc, 1944-09-14 (Pub: 1947-04-01) - filling mercury baremeter
GB601589 Improvements in or relating to apparatus for indicating and/or recording small relative displacements in aneroid barometers, altimeters and similar instruments, Wallace and Tierman Inc, 1941-09-24(same as US2368905) (Pub: 1948-05-10) -
2368905 Aneroid barometer movement, Wallace Charles Frederick, Wallace and Tierman Inc, 1941-09-24 (Pub: 1945-02-06) - (Wiki) greatly improving the sensitivity and fidelity of response..."...to provide an instrument which immediately responds to atmospheric or like pressure changes, without the need for tapping or other agitation..."
GB617063 Improvements in or relating to aneroid type instruments responsive to ambient gaseous pressure,
Wallace and Tierman Inc, 1944-01-07 (Pub: 1949-02-01) -
2385468 Monoalkyl ethers of diethylstilboestrol, Reid Ebenezer Emmet, Wallace and Tierman Inc, 1940-06-25 - (Wiki)
2391060 Recording and indicating system, John R Mackay, Wallace and Tierman Inc, 1939-03-14 - for water chlorination system
2431098 Mechanical movement, Wallace Charles Frederick, Wallace & Tiernan Produets Inc, 1944-01-07 (Pub: 1947-11-18) - improvement on 2368905, provide more sensitive, more accurate and simplified structure for aneroid barometer movements
Calls Kollsman 2150771
2585060 Electrical cell apparatus for testing liquids, Charles F Wallace, Wallace and Tierman Inc, 1948-03-05 - "...
determination of active chlorine, particularly residual chlorine such as may be present in water, sewage or other aqueous liquid that has been subjected to chlorine treatment, e. g. for purification."
2609691 Portable altimeter, John O Kirwan, Wallace and Tierman Inc, 1947-04-04 (Pub: 1952-09-09) -
Intended for topological surveying rugged, portable, accurate, precise
TM 5-6675-203-15 (this is for a similar instrument, not the FA-181)
Operator, Organizational, Field and Depot Maintenance Manual Including Repair Parts and Special Tool Lists,
2 Meter Divisions
(Wallace and Tiernan Type FA-199)
Departments of the army and the Air Force
FM 6-2 Artillery Survey, Aug 1965 has some information on the FA-199 in Chapter 11. Altimetry.
TM 5-235 (archive) Special Surveys, 1940 (1953)-
------------------ from internet archive ------------ reformatted to make sense -----
TM 5-9418 Altimeters, surveying, 15,000-ft, 20-ft divisions, type 15 Wallace& Tiernan Model FA-113, 31 Mar 44
TM 5-9420 Altimeter, surveying, 6000-ft, 10-ft divisions type 6, Wallace &Tiernan, Model FA-112, 31 Mar 44
TM 5-9421 Altimeters, surveying, Wallace & Tiernan Models FA-112, FA-113, and FA-181, 28 Dec 51
TM 5-9422 Compass, sun, universal type, Abrams Model SC-1. 4 Aug 43 (It's interesting that the Sun Compass shows up next in the list.)
This is a differential pressure gauge 0 to 800 mm Hg in steps of 1 mm.
The dial is calibrated for 0 to 400mm (15.75") to 800 mm (31.5") Hg. Note that the standard atmospheric pressure at sea level is:
760 mm Hg or 29.92" Hg or 1013.25 milliBar. As the altitude gets higher the absolute air pressure decreases and in outer space would be zero.
Another way to say that is this is an aneroid barometer (Wiki).
Note as received pointer is on 35 mm Hz, not 760mm. The small dial is near 220 mm Hg not anywhere near almost to 800 mm Hg.
I got it for a very low price since there appears to be a mechanical problem. The fittings are 1/8" pipe thread.
Notice that dial reads CW for increasing pressure (lower right connection) or increasing vacuum (lower left connection). The FA-181 dial reads CCW for increasing altitude.
61-050 Absolute Pressure
62-050 Guage/Compound Pressure
62-075 Differential Pressure
65-120 Precision Pressure Calibrator - external air supply
DP-150 Precision Pressure Calibrator - with hand pump
Fig 1 The front adjusting screw is not available because
no hole in front glass.
Fig 2 Blow-out plug upper left
Case lower left, Capsule lower right
Pulling a vacuum on the case
should make this into a barometer.
Adjusting screw behind plug in center of back.
Fig 3 Scale lifted at about 735 next to the mirror.
Needs to be glued down.
Paul Kollsman (Wiki) founded the Kollsman Instrument Co. There was a Kollsman.com web page but it seems to be offline (Archive Elbit Systems).
I'm guessing the altimeter has an analog output and the Alti-Coder converts that into some type of digital signal that could be fed to an ADS-B transponder (Wiki) and/or a data buss such as MIL-STD-1553 (Wiki). Also guessing that more modern aircraft altimeters have the Alti-coder function built-in rather than use two devices.
The altimeter label:
Altimeter, Pressure Corrected Type, Integrally Lighted, 5AVC 0.68 Amp, Range -1000 to +50000 Feet, FAA TSO-C10b, Kollsman Instrument Corporation, Elmhurst New York
The Alti-coder label:
Alti-Coder, Type No. D3841000201, Serial No. 1757, Kollsman Instrument Corporation, Elmhurst New York.
Fig 4 Knob used to set altitude to zero elevation, i.e.
"Manual Barometer" operation. The barometer reads:
980 millibar or 28.945" Hg.
Paul Kollsman invented the idea of a "setting" (Wiki) on an altimeter so that variations in the barometric pressure caused by weather can be backed out of the altitude reading. This setting is refereed to as the "Kollsman Window" (Wiki). The Wiki article on Paul says he founded the company in 1928, most of the patents do not show the company name.
The early altimeters were pretty much just barometers with the dial face marked in altitude assuming a sea level pressure of 29.92" Hg. This means that they have an error caused by the barometric pressure changes related to the weather. In 1931 the "Kollsman Window" type altimeters where the pilot can set the barometric pressure for the runway where he wants to land were introduced. Now the elevation shown on the dial should match the known elevation of the runway.
The next problem was with the pressurized aircraft flying above 15,000'. The air is much thinner and so there was not enough force from the aneroid capsule to work the mechanism. The "Kollsman Servoed Altimeter" of 1947 fixed this problem by using a motor and null detecting mechanism to drive the pointer. But these do not work without external electrical power, i.e. they fail when the electrical system fails. They do not work without the correct external electrical power.1741702 Indicator, Kollsman Paul, 1929-08-06 - provision for setting a reference altitude (not shown as pressure). Weather barometers have a a range of 26.5" to 31.5" of Mercury. But that covers many variables.
1841606 Turn indicator, Kollsman Paul, 1929-06-25 -
1841607 Turn indicator, Kollsman Paul, 1929-06-25 -
1857311 Indicator, Kollsman Paul, 1931-12-10 - provision for setting the landing strip elevation so the altimeter indicates height above ground.
RE18306 Indicator, Paul Kollsman, Dec. 29, 1931 - Re-Issued
RE19079 Altimeter, Paul Kollsman, Feb. 13, 1934 - Re-Issued
RE20948 Quick Reading Altimeter, Paul Kollsman, Dec. 13, 1938 - Re-Issue
1930899 Aneroid and operating means therefor, Kollsman Paul, 1930-03-07 - temperature compensation is external to the capsules.
See: 2150771 where the temperature compensation is built into the capsule
2034909 Universally balanced aircraft indicator, Kollsman Paul, 1931-03-18 -all transnational forces are balanced so they do not effect the pointer. But rotational forces do effect pointer, especially rocking in the for-aft plane, i.e. pitching.
2041072 Magnetic compass, Kollsman Paul, 1933-07-22 - compensation for the variation of fluid density with temperature by making a part of the float match the liquid density.
2067767 Hydrostatic gauge, Kollsman Paul, 1932-07-01 -
The 1934 Rolls Royce Phantom II uses this type of gas gauge where a pump is used.
2052409 Indicator, Kollsman Paul, 1934-06-18 - Bourdon tube (Wiki) temperature gauge with remote probe.
2067767 Hydrostatic gauge, Kollsman Paul, 1932-07-01 -
2078574 Compensating device for magnetic compasses, Kollsman Paul, 1933-04-20 - maybe Aircraft Pilot's Standby Compass?
2080490 Remote controlled indicator with stabilized head, pitch, and bank indicating unit, Kollsman Paul, 1932-04-05 -
2088559 Miniature electric lamp bulb seat and socket combination, Kollsman Paul, 1937-05-01 - grain of wheat bulb in metal screw-in holder.
2100604 Instrument mounting, Kollsman Paul, 1935-03-05 - maybe the standard aircraft panel instrument with 4 mounting screws.
2140704 Temperature compensator for pressure responsive devices, 1935-09-30 - temperature compensation (See Pressure Altimeters above for equation that includes absolute temperature)
2161870 Automatic means for varying compass card oscillation, Kollsman Paul, 1933-05-17 - improved dampening
2171431 Miniature lamp instrument illuminator system, Kollsman Paul, 1937-10-15 -
2172765 Indicator illumination, Kollsman Paul, 1934-04-05 - grain of wheat bulb in metal screw-in holder.
2150771 Self-compensating aneroid, Kollsman Paul, 1934-12-17 - Temperature compensation between sea level and 30,000 feet.
2154273 Method of and apparatus for making aneroids, Kollsman Paul, 1933-05-15 -
2219243 Gyroscopic instrument, Kollsman Paul, 1939-06-08 - gyroscopic stabilized magnetic compass
2203824 Directional instrument, Kollsman Paul, 1940-01-31 - Turn Indicator
2215447 Turn indicator, Kollsman Paul, 1937-07-30 - gyroscopic
2224732 Directional instrument, 1940-01-31 -
2232537 Remote controlled indicator with stabilized head, pitch, and bank indicating unit, Kollsman Paul, (no assignee), 1937-05-17 -gyroscopic
2437064 Two-phase motor control, Jr John H Andresen, Schneider Electric USA Inc, 1946-01-29
the gap between contacts (5) and (6) is changed by the motor running CW or CCW in response to changes in the length of the stack of three barometric capsules.
2557856 Altimeter, Angst Walter r, John H Andresen, KOLLSMAN INSTR CORP, 1947-05-06 -
at sea level a change of 100' = 0.1" Hg = 0.001" movement of the chamber/element/bellows/capsule
at 80,000' a change of 100' = 0.004" Hg = 0.00004" capsule movement
a motor is used with a spiral cam to sense the position of the capsule.
See 2437064 above for motor control.
2579902 Instrument for correlating air speed, angle of attack, and aircraft loading,
Victor E Carbonara, Jr John H Andresen, KOLLSMAN INSTR CORP, 1945-08-04 -
2604117 High-power diaphragm capsule assembly, Angst Walter, KOLLSMAN INSTR CORP, 1949-07-02 - capable of driving two pointers with a 10:1 ratio.
2689480 Sensitive wide range altimeter, Angst Walter, KOLLSMAN INSTR CORP, 1950-04-15 - up to 80,000 feet requires new techniques because of the very low pressure hence low forces available.
2829833 Azimuth Counter - moved to MD1 Astro Compass web page
3314061 Servo altimeter, William F Magagnos, KOLLSMAN INSTR CORP, 1963-06-24 -
Air Traffic Control Transponder output (80)
Patents on labels
2689480 see above
2851002 Aircraft instrument-dual drum scale, Angst Walter, KOLLSMAN INSTR CORP, 1958-09-09 -
3009358 Aircraft instrument-remote control-fail safe, James W Angus, KOLLSMAN INSTR CORP, 1961-11-21 - Mechanical pointer continues to function even if electrical system fails, but not as accurate. Note in photos the altimeter is reading close to my elevation.
3040168 Instrument lighting device, Stearns Thornton, KOLLSMAN INSTR CORP, 1962-06-19 -
3043580 Return mechanism for fail safe instruments, James W Angus, KOLLSMAN INSTR CORP, 1962-07-10 - glare reduction
3242737 Encoding system for a navigational apparatus,
Grande Robert S De, Baron Leonard, KOLLSMAN INSTR CORP,1966-03-29 -
------------------end of label patents-------------
3009357 Aircraft instrument-remote control-fail safe, James W Angus, KOLLSMAN INSTR CORP, 1961-11-21
3160012 Fail safe aircraft instrument, Jr John H Andresen, KOLLSMAN INSTR CORP, 1964-12-08 -
3152325 Hybrid optical encoder, Paul F Kaestner, KOLLSMAN INSTR CORP, 1964-10-06 - starting with a conventional Gray Code encoder then . . . "The present invention is directed to concurrently provide the fine readout and, at the same time, eliminate first order eccentricity errors in the optical disk." provides 16 bits from a 3" dia disk where prior art required a 9" disk.
3262416 Altimeter structure, David B Nichinson, KOLLSMAN INSTR CORP, 1966-07-26 - instead of setting the pressure at the landing runway you set it's elevation.
3742325 Plural input mode servo driven air data computer, J Andresen, Intercontinental Dynamics Corp, 1973-06-26 - John Andersen is the same inventor that appears above on many Kollsman instruments. This is the first Air Data Computer (Wiki). The Alti-Coder is an intermediate solution.
This is an all mechanical altimeter with the "Kollsman Window".
“History of [the] U.S. Army Topographic Laboratories (1920 to 1973)”.
Chapter 6. R&D Programs mentions:History of the Altimeter
pdf g 81 W&T altimeters adopted 1943
pdf pg 83 Astrolabs
2600266 Pendulum retaining means, Rothweiler Charles, David White Company, 1947-03-06 - 60 deg pendulum Astrolabe (Google)
Analog Weather - Instruments & some pdf manuals
PRC68, Alphanumeric Index of Web pages, Contact, Products for Sale
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