Hypersonic airbreathing propulsion/airframe integration

Recent interest in airbreathing hypersonic flight has centered around the need to develop advanced space launch systems which can reduce the cost of inserting payloads in orbit and make space more accessible. An effect of the thermal environment is to require the vehicle to operate at high altitudes, in very thin air, to maintain aircraft structural load limits. The high altitudes at which the hypersonic vehicle must operate give rise to the concept of an airframe integrated propulsion system to provide a much larger inlet and nozzle to process the required volume of air at low density, atmospheric conditions. In the integrated system, the forward portion of the vehicle compresses the air flow and serves as the external portion of the inlet; the aftbody completes the expansion process for the nozzle. In addition, the engine, which is contained between the body and the forebody shock wave, lends itself to a modular integration of a number of separate engines. In this manner, a relatively small engine can be defined to allow engine development in existing ground facilities

Versatile Dye Laser Generator-Amplifier System for Intense Tunable Picosecond Pulse Generation

Abstract. Passively mode-locked ruby-laser pulses are used to generate nearly diffraction-limited picosecond light pulses in a dye cell by longitudinally amplified spontaneous emission. The output pulses are amplified in three longitudinally pumped dye cells, then spectrally filtered with a grating spectrometer and finally reamplified in a fourth dye amplifier in order to generate intense frequency tunable picosecond light pulses. PACS: 42.55M, 42.60 Various pulsed dye laser systems are available for tunable picosecond pulse generation [1, 2]. Flash-lamp pumped mode-locked dye lasers [3], synchron-ously pumped lasers [4], short-cavity resonators [5], quenched transient lasers [6], distributed feedback lasers [7], and amplified spontaneous emission sys-tems [8] have been investigated. The arrangements applying amplified spontaneous emission (ASE) may be grouped into longitudinall

Scramjet nozzle design and analysis as applied to a highly integrated hypersonic research airplane

Engine-nozzle airframe integration at hypersonic speeds was conducted by using a high-speed research aircraft concept as a focus. Recently developed techniques for analysis of scramjet-nozzle exhaust flows provide a realistic analysis of complex forces resulting from the engine-nozzle airframe coupling. By properly integrating the engine-nozzle propulsive system with the airframe, efficient, controlled and stable flight results over a wide speed range

The Misappropriation of Trust Fund Taxes Under the Guise of Reasonable Cause

Employers are generally required to withhold income, Social Security, and Medicare taxes from their employees\u27 paychecks. Employers hold these taxes in trust until they are deposited or otherwise paid over to the government. Since one of the most common problems faced by owners and managers of businesses is the lack of adequate cash to satisfy their numerous immediate obligations, this system creates a temptation for the employer to use the withheld funds to cover its costs. Short-term bank loans are often either unavailable or unaffordable, and the employer\u27s own debtors may be unable to pay or not yet obligated to pay. Certain creditors, such as landlords, suppliers, shipping agents, and employees, must be paid on time or the business would cease to operate. When confronted with this dilemma, the employer may turn to the one source of cash immediately available: the taxes withheld from employee paychecks. This decision is usually seen as a short-term fix to a temporary cash flow problem; the employer believes it will be able to meet its tax obligations when due. If the employer manages to replenish its cash before the withheld taxes are due, the employer satisfies its obligation and avoids sanction. If the payment is late, the employer may be liable for penalties. On the other hand, if cash flow problems are permanent, the employer may be entirely unable to fulfill its obligation to pay over the withheld taxes. If the company fails to pay the taxes when required, a full range of tax collection devices are available to the Internal Revenue Service (IRS). Withheld taxes are referred to as trust fund taxes, in reference to Internal Revenue Code (Code) section 7501, which states, the amount of tax so collected or withheld shall be held to be a special fund in trust for the United States. Under general trust principles, the employers\u27 use of funds held in trust, as are trust fund taxes, constitutes a misappropriation of those funds. However, general common law trust principles cannot be applied wholesale to this context. For example, despite the creation of a trust, there is no requirement that the trust fund taxes be segregated from the employer\u27s general operating funds as soon as the trust taxes are incurred. While the IRS has the right to demand segregation, and even criminalize the failure to do so, segregation does not help the government collect trust fund taxes that have already been misappropriated. Generally, the withholding system only requires that the employer deposit the withheld taxes, pay the taxes with the quarterly employment tax return, or both

Structural concepts and experimental considerations for a versatile high-speed research airplane

Future aircraft may be hydrogen fueled and fly at hypersonic speeds. The resulting environments will require new structural concepts to satisfy performance goals. Large representative structures will have to be flight tested prior to commitment to a costly vehicle fleet. To perform flight tests, a versatile, economical, high-speed research airplane is defined. Results of this study including experimental considerations for a hypersonic research airplane are reported

Orbiter/launch system

The system includes reusable turbojet propelled booster vehicles releasably connected to a reusable rocket powered orbit vehicle. The coupled orbiter-booster combination takes off horizontally and ascends to staging altitude and speed under booster power with both orbiter and booster wings providing lift. After staging, the booster vehicles fly back to Earth for horizontal landing and the orbiter vehicle continues ascending to orbit

A Pre-Mixed Shock-Induced-Combustion Approach to Inlet and Combustor Design for Hypersonic Applications

The need for efficient access to space has created interest in airbreathing propulsion as a means of achieving that goal. The NASP program explored a single-stage-to-orbit approach which could require scramjet airbreathing propulsion out to Mach 16 to 20. Recent interest in global access could require hypersonic cruise engines operating efficiently in the Mach 10 to 12 speed range. A common requirement of both these types of propulsion systems is that they would have to be fully integrated with the aero configuration so that the forebody becomes a part of the external compression inlet and the nozzle expansion is completed on the vehicle aftbody