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48-434: NASA's Pathfinder Technology Demonstrator ( PTD ) Project is a series of tech demonstrations of technologies aboard a series of nanosatellites known as CubeSats , providing significant enhancements to the performance of these versatile spacecraft. Each of the five planned PTD missions consist of a 6-unit (6U) CubeSat with expandable solar arrays. Flight qualification and demonstration of these technologies carried aboard

96-410: A prototype , rough example or otherwise incomplete version of a conceivable product or future system, put together as proof of concept with the primary purpose of showcasing the possible applications, feasibility, performance and method of an idea for a new technology. They can be used as demonstrations to the investors , partners, journalists or even to potential customers in order to convince them of

144-586: A 300 mile orbit to Earth, and plans to test 200-1,000 Gbps. On April 28, 2023, 200 gigabit per second (Gbps) throughput was achieved. A 6U cubesat to demonstrate the Lightweight Integrated Solar Array and anTenna ( LISA-T ), a very high-power, low-volume deployable solar array with an integrated antenna. LISA-T is being developed by NASA’s Marshall Space Flight Center in Huntsville, Alabama. LISA-T offers lower mass and stored volume as well as

192-491: A 90-day lifetime after it is released in low Earth orbit . Each spacecraft will include different test payloads such as propulsion systems for orbital station-keeping, maneuvering and interplanetary transit, laser high bandwidth communications , or high precision attitude control (orientation) systems to stabilize the spacecraft and point the designated instruments with high accuracy. Examples of novel systems to be tested are an electrospray thruster, water-based propulsion, and

240-449: A greater power per unit mass compared to current available solar array technology. As of December 2023, no launch date is set. The nanosatellite will be launched along with PTD-R on SpaceX's Transporter-11 mission out of Vandenberg Space Force Base . Transporter-11 launched in August 2024. Tech demo A technology demonstration (or tech demo ), also known as demonstrator model , is

288-462: A higher exit velocity of the propellant, increasing thrust. For rockets traveling from the Earth to orbit, a simple nozzle design is only optimal at one altitude, losing efficiency and wasting fuel at other altitudes. Just past the throat, the pressure of the gas is higher than ambient pressure and needs to be lowered between the throat and the nozzle exit by expansion. If the pressure of the exhaust leaving

336-455: A nozzle designed for sea-level operation will quickly lose efficiency at higher altitudes. In a multi-stage design, the second stage rocket engine is primarily designed for use at high altitudes, only providing additional thrust after the first-stage engine performs the initial liftoff. In this case, designers will usually opt for an overexpanded nozzle (at sea level) design for the second stage, making it more efficient at higher altitudes, where

384-472: A number of concepts and simplifying assumptions: As the combustion gas enters the rocket nozzle, it is traveling at subsonic velocities. As the throat constricts, the gas is forced to accelerate until at the nozzle throat, where the cross-sectional area is the least, the linear velocity becomes sonic . From the throat the cross-sectional area then increases, the gas expands and the linear velocity becomes progressively more supersonic . The linear velocity of

432-402: A perfectly expanded nozzle case, where p e = p o {\displaystyle p_{\text{e}}=p_{\text{o}}} , the formula becomes In cases where this may not be so, since for a rocket nozzle p e {\displaystyle p_{\text{e}}} is proportional to m ˙ {\displaystyle {\dot {m}}} , it

480-504: A rocket nozzle. The nozzle's throat should have a smooth radius. The internal angle that narrows to the throat also has an effect on the overall efficiency, but this is small. The exit angle of the nozzle needs to be as small as possible (about 12°) in order to minimize the chances of separation problems at low exit pressures. A number of more sophisticated designs have been proposed for altitude compensation and other uses. Nozzles with an atmospheric boundary include: Each of these allows

528-446: A solid center-body. ED nozzles are radial out-flow nozzles with the flow deflected by a center pintle. Controlled flow-separation nozzles include: These are generally very similar to bell nozzles but include an insert or mechanism by which the exit area ratio can be increased as ambient pressure is reduced. Dual-mode nozzles include: These have either two throats or two thrust chambers (with corresponding throats). The central throat

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576-434: A stand-alone form of computer art. Sales Engineering staff, often bearing the title Sales Engineer or Presales Consultant, will prepare technology demonstrations for business meetings or seminars to show capabilities of business products. This can include both software and hardware products, and can show multiple products integrating together. Usually, a demonstration is less than a Proof of concept , but can come some of

624-537: A very long nozzle has significant mass, a drawback in and of itself. A length that optimises overall vehicle performance typically has to be found. Additionally, as the temperature of the gas in the nozzle decreases, some components of the exhaust gases (such as water vapour from the combustion process) may condense or even freeze. This is highly undesirable and needs to be avoided. Magnetic nozzles have been proposed for some types of propulsion (for example, Variable Specific Impulse Magnetoplasma Rocket , VASIMR), in which

672-739: A very precise attitude control system. A Request for Proposal (RFP) NNA16574335R was issued, on 12 February 2016, for the delivery of a spaceflight qualified 6U CubeSat spacecraft to be operated by NASA for its Pathfinder Technology Demonstrator (PTD) Project to accommodate technology subsystems , hereafter referred to as the payload. One flight demonstration is planned for a low thrust propulsion system with options for four follow-on technology demonstrations. Follow‐on missions may include payloads such as higher thrust propulsion systems or payloads such as optical communications or high precision attitude determination and control systems. Request for proposal response date: 4 April 2016. The PTD-1 spacecraft

720-457: Is a hybrid chemical/electrical technology to provide propulsion using water. It uses an electrolysis cell to split water propellant into gaseous hydrogen and oxygen that are stored under pressure in separate tanks. The system then burns the hydrogen and oxygen mix in a simple thruster nozzle to provide up to 1 Newton and a specific impulse of 258 seconds. This propulsion system is being developed by Tethers Unlimited, Inc. In pure water, at

768-459: Is accelerated in the opposite direction. The thrust of a rocket engine nozzle can be defined as: the term in brackets is known as equivalent velocity, The specific impulse I sp {\displaystyle I_{\text{sp}}} is the ratio of the thrust produced to the weight flow of the propellants . It is a measure of the fuel efficiency of a rocket engine. In English Engineering units it can be obtained as where: For

816-440: Is as follows: using a quasi-one-dimensional approximation of the flow, if ambient pressure is higher than the exit pressure, it decreases the net thrust produced by the rocket, which can be seen through a force-balance analysis. If ambient pressure is lower, while the force balance indicates that the thrust will increase, the isentropic Mach relations show that the area ratio of the nozzle could have been greater, which would result in

864-416: Is at a premium. They are, of course, harder to fabricate, so are typically more costly. There is also a theoretically optimal nozzle shape for maximal exhaust speed. However, a shorter bell shape is typically used, which gives better overall performance due to its much lower weight, shorter length, lower drag losses, and only very marginally lower exhaust speed. Other design aspects affect the efficiency of

912-401: Is consistent with above typical values. The technical literature can be very confusing because many authors fail to explain whether they are using the universal gas law constant R which applies to any ideal gas or whether they are using the gas law constant R s which only applies to a specific individual gas. The relationship between the two constants is R s = R / M , where R is

960-558: Is currently under development and fabrication. It will demonstrate a propulsion system with a water-based propellant obtained from electrolysis of water . While in orbit, the system separates onboard water into hydrogen and oxygen propellants by applying an electric current through the water. PTD-1 is scheduled for launch in December 2020 as part of the ride-share ELaNa mission 35 on board a Falcon 9 rocket. PTD-1 launched January 24th 2021 on SpaceX rideshare Transporter-1 mission . HYDROS

1008-483: Is of a standard design and is surrounded by an annular throat, which exhausts gases from the same (dual-throat) or a separate (dual-expander) thrust chamber. Both throats would, in either case, discharge into a bell nozzle. At higher altitudes, where the ambient pressure is lower, the central nozzle would be shut off, reducing the throat area and thereby increasing the nozzle area ratio. These designs require additional complexity, but an advantage of having two thrust chambers

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1056-416: Is possible to define a constant quantity that is the vacuum I sp,vac {\displaystyle I_{\text{sp,vac}}} for any given engine thus: and hence: which is simply the vacuum thrust minus the force of the ambient atmospheric pressure acting over the exit plane. Essentially then, for rocket nozzles, the ambient pressure acting on the engine cancels except over the exit plane of

1104-744: Is that they can be configured to burn different propellants or different fuel mixture ratios. Similarly, Aerojet has also designed a nozzle called the "Thrust Augmented Nozzle", which injects propellant and oxidiser directly into the nozzle section for combustion, allowing larger area ratio nozzles to be used deeper in an atmosphere than they would without augmentation due to effects of flow separation. They would again allow multiple propellants to be used (such as RP-1), further increasing thrust. Liquid injection thrust vectoring nozzles are another advanced design that allow pitch and yaw control from un-gimbaled nozzles. India's PSLV calls its design "Secondary Injection Thrust Vector Control System"; strontium perchlorate

1152-634: Is to test the physics of key new technologies in order to enhance small spacecraft and make them able to reach new destinations and operate in new environments. These technologies will be tested in low Earth orbit for potential future application in small spacecraft operating in Earth orbit or in deep space. Technologies demonstrated by PTD flights may be applicable and scalable to larger spacecraft. The project plans to fly five 6U CubeSat orbital missions, coded PTD-1 through PTD-5, at 6-month intervals, each flight assessing different technologies. Each mission will have

1200-620: The Lawrence Livermore National Lab developed Payload "Deep Purple". Deep Purple is a technology demonstration of a co-aligned pair of UV/SWIR telescopes. NASA PTD SITE https://www.nasa.gov/smallspacecraft/pathfinder-technology-demonstrator/ PTD-3, a 6U cubesat, launched on May 25 2022 on SpaceX's Transporter-5 rideshare mission , includes the 3U TeraByte InfraRed Delivery (TBIRD) laser communications test. TBIRD will send data at 200 Gbps from LEO to ground stations. By Dec 2022, TBIRD demonstrated 100 Gbps data transfers from

1248-599: The PTD missions are expected to benefit future government and commercial missions. These include propulsion systems and sub-systems that stabilize and point the spacecraft to high accuracy in order to use a laser communications system capable of high-speed broadband. The first mission, PTD-1, was scheduled for launch in December 2020 on a Falcon 9 rocket, from Cape Canaveral, as part of the ride-share ELaNa mission 35, launched on January 24th, 2021, and demonstrated HYDROS-C water-based propellant system. PTD-3 launched on May 25 2022 on

1296-713: The SpaceX Transporter-5 rideshare and demonstrated the TBIRD infrared communication system. The Pathfinder Technology Demonstrator (PTD) Project is led by NASA's Ames Research Center in California , in collaboration with NASA's Glenn Research Center in Ohio . The PTD project is managed and funded by NASA's Small Spacecraft Technology Program (SSTP) within the Space Technology Mission Directorate. The overall goal

1344-487: The above equation, assume that the propellant combustion gases are: at an absolute pressure entering the nozzle of p  = 7.0   MPa and exit the rocket exhaust at an absolute pressure of p e = 0.1   MPa; at an absolute temperature of T = 3500   K; with an isentropic expansion factor of γ = 1.22 and a molar mass of M  = 22 kg/kmol. Using those values in the above equation yields an exhaust velocity v e = 2802 m/s or 2.80 km/s which

1392-463: The ambient pressure is lower. This was the technique employed on the Space Shuttle 's overexpanded (at sea level) main engines (SSMEs), which spent most of their powered trajectory in near-vacuum, while the shuttle's two sea-level efficient solid rocket boosters provided the majority of the initial liftoff thrust. In the vacuum of space virtually all nozzles are underexpanded because to fully expand

1440-401: The combustion chamber leads into a nozzle which converts the energy contained in high pressure, high temperature combustion products into kinetic energy by accelerating the gas to high velocity and near-ambient pressure. Simple bell-shaped nozzles were developed in the 1500s. The de Laval nozzle was originally developed in the 19th century by Gustaf de Laval for use in steam turbines . It

1488-439: The engine is almost inevitably going to be grossly over-expanded. The ratio of the area of the narrowest part of the nozzle to the exit plane area is mainly what determines how efficiently the expansion of the exhaust gases is converted into linear velocity, the exhaust velocity, and therefore the thrust of the rocket engine. The gas properties have an effect as well. The shape of the nozzle also modestly affects how efficiently

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1536-405: The exiting exhaust gases can be calculated using the following equation where: Some typical values of the exhaust gas velocity v e for rocket engines burning various propellants are: As a note of interest, v e is sometimes referred to as the ideal exhaust gas velocity because it based on the assumption that the exhaust gas behaves as an ideal gas. As an example calculation using

1584-506: The expansion of the exhaust gases is converted into linear motion. The simplest nozzle shape has a ~15° cone half-angle, which is about 98% efficient. Smaller angles give very slightly higher efficiency, larger angles give lower efficiency. More complex shapes of revolution are frequently used, such as bell nozzles or parabolic shapes. These give perhaps 1% higher efficiency than the cone nozzle and can be shorter and lighter. They are widely used on launch vehicles and other rockets where weight

1632-470: The flow of plasma or ions are directed by magnetic fields instead of walls made of solid materials. These can be advantageous, since a magnetic field itself cannot melt, and the plasma temperatures can reach millions of kelvins . However, there are often thermal design challenges presented by the coils themselves, particularly if superconducting coils are used to form the throat and expansion fields. The analysis of gas flow through de Laval nozzles involves

1680-441: The gas's the nozzle would have to be infinitely long, as a result engineers have to choose a design which will take advantage of the extra expansion (thrust and efficiency) whilst also not adding excessive weight and compromising the vehicle's performance. For nozzles that are used in vacuum or at very high altitude, it is impossible to match ambient pressure; rather, nozzles with larger area ratio are usually more efficient. However,

1728-508: The many state of the art systems whilst maintaining the 1/2 U form factor. PTD-2 was also the intended platform for a NASA demonstration of the GLOBALSTAR satellite communication modem. PTD-2 was terminated after a mishap during integration and test of the Space Vehicle. It was ultimately replaced by PTD-2R, also known as PTD-R. PTD-R was launched 8/16/2024 on SpaceX transporter-11, with

1776-408: The negatively charged cathode, a reduction reaction takes place, with electrons (e) from the cathode being given to hydrogen cations to form hydrogen gas. The half reaction , balanced with acid, is: At the positively charged anode, an oxidation reaction occurs, generating oxygen gas and giving electrons to the anode to complete the circuit: The propulsion system uses the electricity generated by

1824-430: The nozzle exit is still above ambient pressure, then a nozzle is said to be underexpanded ; if the exhaust is below ambient pressure, then it is overexpanded . Slight overexpansion causes a slight reduction in efficiency, but otherwise does little harm. However, if the exit pressure is less than approximately 40% that of ambient, then "flow separation" occurs. This can cause exhaust instabilities that can cause damage to

1872-429: The nozzle, control difficulties of the vehicle or the engine, and in more extreme cases, destruction of the engine. In some cases, it is desirable for reliability and safety reasons to ignite a rocket engine on the ground that will be used all the way to orbit. For optimal liftoff performance, the pressure of the gases exiting nozzle should be at sea-level pressure when the rocket is near sea level (at takeoff). However,

1920-543: The nozzle. This separation generally occurs if the exit pressure drops below roughly 30-45% of ambient, but separation may be delayed to far lower pressures if the nozzle is designed to increase the pressure at the rim, as is achieved with the Space Shuttle Main Engine (SSME) (1-2 psi at 15 psi ambient). In addition, as the rocket engine starts up or throttles, the chamber pressure varies, and this generates different levels of efficiency. At low chamber pressures

1968-414: The pressure upstream due to the very high jet velocity. Therefore, for supersonic nozzles, it is actually possible for the pressure of the gas exiting the nozzle to be significantly below or very greatly above ambient pressure. If the exit pressure is too low, then the jet can separate from the nozzle. This is often unstable, and the jet will generally cause large off-axis thrusts and may mechanically damage

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2016-400: The rocket engine in a rearward direction, while the exhaust jet generates forward thrust. As the gas travels down the expansion part of the nozzle, the pressure and temperature decrease, while the speed of the gas increases. The supersonic nature of the exhaust jet means that the pressure of the exhaust can be significantly different from ambient pressure—the outside air is unable to equalize

2064-507: The solar arrays to power the miniature water electrolysis. The demonstration will test propulsion performance through programmed changes in spacecraft velocity and altitude. PTD-2 is a 6U CubeSat technology demonstration mission to demonstrate an improved attitude determination and control system that was developed under the Tipping Point Program . The HyperXACT design will provide 5X improvement in reliability and pointing over

2112-411: The supersonic flow to adapt to the ambient pressure by expanding or contracting, thereby changing the exit ratio so that it is at (or near) optimal exit pressure for the corresponding altitude. The plug and aerospike nozzles are very similar in that they are radial in-flow designs but plug nozzles feature a solid centerbody (sometimes truncated) and aerospike nozzles have a "base-bleed" of gases to simulate

2160-408: The universal gas constant, and M is the molar mass of the gas. Thrust is the force that moves a rocket through the air or space. Thrust is generated by the propulsion system of the rocket through the application of Newton's third law of motion: "For every action there is an equal and opposite reaction". A gas or working fluid is accelerated out the rear of the rocket engine nozzle, and the rocket

2208-411: The viability of the chosen approach, or to test them on ordinary users. Technology demonstrations are often used in the computer industry, emerging as an important tool in response to short development cycles in software and hardware development. Computer technology demos should not be confused with demoscene -based demos , which, although often demonstrating new software techniques, are regarded as

2256-432: The way to showing how a business project may be justified. Large companies with tens or hundreds of Sales Engineers will often have a team who specialize in the production of demonstration systems and plans. Rocket engine nozzle Simply: propellants pressurized by either pumps or high pressure ullage gas to anywhere between two and several hundred atmospheres are injected into a combustion chamber to burn, and

2304-431: Was first used in an early rocket engine developed by Robert Goddard , one of the fathers of modern rocketry. It has since been used in almost all rocket engines, including Walter Thiel 's implementation, which made possible Germany's V-2 rocket. The optimal size of a rocket engine nozzle is achieved when the exit pressure equals ambient (atmospheric) pressure, which decreases with increasing altitude. The reason for this

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