Operating altitude

R. Geyer, R. Fay, G. Denoux, C. Giammona, K. Binkley, and R. Jamail. Aerial dispersant application Assessment of sampling methods and operational altitudes. Mar Spill Response Corp Tech Rep Ser 93-0091,... 

Many of the problems in combustion research stem from the difficulty of burning in combustors at high speeds and altitudes. The advances in this field have been tremendous. The jet-turbine combustor will release 500 times the energy for a given space as the stationary boiler furnace. Its operating problems have been overcome (with the usual partial aid of fundamental combustion research) so that the limiting operational altitudes of aircraft are well above 50,000 feet and the speeds are supersonic. 

The increased performance meant that Allied planes were better than Axis planes by a factor of 15 percent to 30 percent in engine power for take-off and climbing 25 percent in payload 10 percent in maximum speed and 12 percent in operational altitude. In the first six months of 1940, at the time of the Battle of Britain, 1.1 million barrels per month of 100-octane aviation gasoline was shipped to the Allies. Houdry plants produced 90 percent of this catalytically cracked gasoline during the first two years of the war. (12)... 

The Federal Aviation Administration (FAA) has not yet decided how UAVs will be incorporated into civihan airspace, which has kept their commercial use in this country to a minimum. Mini-UAVs offer a solution to this problem because they can operate safely at altitudes below the operating altitude of full-size air traffic and, because of their size, speed, and weight, they pose little threat to the pubhc. 

Geyer, R. Fay, R. Giammona, C. Binkley, K. Denoux, G. Jamail, R. Aerial Dispersant Application Assessment of Sampling Methods and Operational Altitudes, Volume 1, MSRC Technicd Report 93-009.1, Marine Spill Research Gorporation, Washington, DG, 1993. 

The maximum operation altitude of the above mentioned engine is 4.5 km from sea level. Equation (3.1) shows the relation between temperature, altitude and pressure. 

Low Density Gases. A fan may have to operate on low density gas because of temperature, altitude, gas composition (high water vapor content of the gas can be a cause of low density), reduced process pressure, or a combination of such causes. To develop a required pressure, the fan has to operate at a considerably higher speed than it would at atmospheric pressure, and hence it must operate much closer to top wheel speed. Bearing life is shorter, and the fan tends to vibrate more or can be overstressed more easily by a slight wheel unbalance. Abrasion of the blades from dust particles is more severe. Therefore, a sturdier fan is needed for low density gas service. 

A vacuum system can be constmcted that includes a solar panel, ie, a leak-tight, instmmented vessel having a hole through which a gas vacuum pump operates. An approximate steady-state base pressure is estabUshed without test parts. It is assumed that the vessel with the test parts can be pumped down to the base pressure. The chamber is said to have an altitude potential corresponding to the height from the surface of the earth where the gas concentration is estimated to have the same approximate value as the base pressure of the clean, dry, and empty vacuum vessel. 

Control of nitrogen oxides ia aircraft exhaust is of increa sing concern because nitrogen oxides react with ozone ia the protective layer of atmosphere which exists ia the altitude region where supersonic aircraft operate. Research is under way to produce a new type of combustor which minimizes NO formation. It is an essential component of the advanced propulsion unit needed for a successflil supersonic transport fleet. 

Ground turbine fuels are not subject to the constraints of an aircraft operating at reduced pressures of altitude. The temperature of fuel in ground tanks varies over a limited range, eg, 10—30°C, and the vapor pressure is defined by a safety-handling factor such as flash point temperature. Volatile fuels such as naphtha (No. 0-GT) are normally stored in a ground tank equipped with a vapor recovery system to minimise losses and meet local air quaUty codes on hydrocarbons. 

For motors specified for operation at an altitude higher than 1000 m. btit not in excess of 4000 m. the correction may be made as shown in Table 1.8. 

Ambient temperature, altitude and atmospheric conditions at the place of installation of electrical equipment are considered to be the service conditions for the equipment to operate and perform its duties. All electrical equipment is designed for specific service conditions and variations may influence its performance. Below we analyse the influence of such non-standard service conditions on the performance of equipment and the required safeguards to achieve its required performance. 

Altitude has an effect on cooling tower performance but in a unique way. Air handlers, air cooled condensers and the like are typically made to operate at higher speeds (or, with a steeper fan pitch) as altitude increases in order to maintain the... 

A corresponding situation occurs at high altitude, where one-third of the sea-level power available has been lost due to low atmospheric pressure. This low air density also reduces aerodynamic drag, but rolling resistance is unaffected by altitude. As a result, power resei"ve is seen to suffer. In fact, at this altitude, the power available in fourth gear is insufficient to operate the vehicle on a 6 percent grade at any speed without downshifting. 

Aircraft engines operate in an environment that gets increasingly colder as the aircraft climbs to altitude, so Stirling aircraft engines, unlike any other type of aircraft engine may derive some performance benefit from climbing to altitude. The communities near airports would benefit from the extremely quiet... 

Because all compressors do not operate at sea level pressure conditions, it is important to use the proper absolute pressure at the particular locality. Figure 12-23 is useful for converting altitude to pressure (or see Appendix A-6). 

Table 14-3 indicates the derating fectors for the effect of altitude on standard Class B motors. Motors are designed to operate within Class B temperature rise limits when operated at rated horsepower at altitudes up to 3,300 ft. For operation of this class of motor at altitudes greater than 3,300 ft at less than the rated horsepower, the derating factors shown in Table 14-3 should be used. 

Effect of Altitude on Operation of Large 200-2,000 hp Induction Motors (for Altitudes Greater Than 3,300 ft)... 

Motors are designed to operate within Class B temperature rise limits when operated at rated horsepower at altitudes up to 3,300 ft. 

For operation between 3,300 and 5,500 ft altitude at rated horsepower using Class F temperature rise limits, add 3% to the basic motor price. 

For operation greater than 5,500 ft altitude, refer to factor for frame size and price. 

For operation of a standard Class B motor at altitudes greater than 3,300 ft at less than rated horsepower, use the derating factor. 

The foregoing values of temperature rise are based upon operation at altitudes of 3,300 ft (1,000 meters) or less. For temperature rises for motors intended for operation at altitudes above 3,300 ft (1,000 meters), see 14.04. 

When an internal combustion engine is to be used at different operating conditions (altitude) other than the standard conditions that the engine was rated at, it is necessary to derate the engine specifications. The brake horsepower H at pressure and temperature conditions other than standard can be obtained from the following ... 

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