Napier nomad

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The compressor and turbine assemblies of the Nomad were tested during , and the complete unit was run in October The prototype was installed in the nose of an Avro Lincoln heavy bomber for testing: it first flew in and appeared at the Farnborough Air Display on 10 September It had a specific fuel consumption sfc of 0.

The turbine which also received an additional stage was now only used to drive the compressor, and feed back any excess power to the main shaft using a Beier variable-ratio gear ; [5] the separate propeller from the turbine was deleted, just as the whole of the " afterburner " system with its valves etc. So the system was now like a combination of a mechanical supercharger , and a turbocharger without any need for bypass. The result was smaller and considerably simpler: a single engine driving a single propeller.

The wet liners of the cylinders of the Nomad I were changed for dry liners. The engine proved bulky, like the Nomad I before it, and in the meantime several dummy engines were used on the Shackleton for various tests.

A further development, the Nomad Nm. The design was also considered for the Canadair Argus , a similar maritime patrol aircraft aircraft being designed for the Royal Canadian Air Force. This design turned to the Wright R , the design the Nomad was intending to best. Udvar-Hazy Center in Virginia. Data from Flight [12]. From Wikipedia, the free encyclopedia. British diesel aircraft engine. World Encyclopaedia of Aero Engines. Cambridge, England: Patrick Stephens. ISBN Flight : Archived from the original on 5 March Diesel Progress.

ISSN Archived from the original on 13 April Archived from the original on 16 April Flight : — Archived from the original on 8 October Truly a bizarre engine; 12 cylinder, two-stroke diesel. I would love to hear this thing run. I wonder how many were built? BTW, Great post! Whatever happened to that one? Just a handful, I gather. It was rapidly superseded by the turboprop and pure jet engine tech of the time.

And thanks! As for the 5-stroke engine, it was developed by Ilmor, an engine builder closely associated withe Mercedes. More info here:. If the Napier Nomad engine is redeveloped with up to date materials and technoligy it could be be a brillant power plant for medium size airliners and cargo air craft , If a reworked Mustang P51 was fitted with this engine and further developed it would an ideal war plane against enemy insurgents.

I bet if it was revived and manufactured with modern technology it would be a real masterpiece. Name required. Mail will not be published required. Connect with us on Twitter and Facebook! Papabrewsky says:. June 23, at PM. Matt says:.

Извиняюсь, но, город стамбул мое почтение

To accurately represent this flow area, knowledge of the engine scavenge ports and exhaust port equivalent time-areas are necessary [7]. As the porting geometry and dimensions on the Nomad are not obtainable, recourse to other methods was necessary. From this information, an equivalent area and realistic discharge coefficient was calculated With all parameters input and calibrations performed, the model was run for validation with the test data provided in Reference 2 at the rated power, sea level conditions and is considered the baseline.

Table 2 shows the comparison between the most pertinent calculated performance parameters versus the test data. Note both temperature and pressure at sea level conditions and all other altitudes considered reflect those of standard atmosphere [8]. This is standard practice in calibrating a model under a baseline condition. Once these relationships are established, the compressor and turbine efficiencies are held constant for all simulations that follow. Figure 6 displays a cylinder pressure versus crank angle curve for the piston engine from the simulation.

An air-standard cycle dark blue curve is also represented for academic interest and reference. The latter curve shows the distinct instantaneous cylinder pressure drop at EO of Baseline pressure is Figure 8 displays the pressure versus volume relationship of the turbomachine.

Here baseline pressure is at ambient Note the slope from peak point 2 to Figure 9 displays the high pressure - low volumetric piston engine with the low pressure - high volumetric displacement turbomachine plotted on the same ordinate and abscissa scales. This rather dramatically shows the significance of the two devices working in concert and the reason why the compound cycle is so beneficial in producing high power outputs with excellent thermal efficiency.

With the model calibrated and in good agreement with test data, a second simulation was run, again relying on data published in Reference 2. The second run was made at 7, feet altitude above MSL Mean Sea Level where it was stated that take-off boost and thus maximum rated power is still attainable. Detailed data at this altitude is not given in the cited reference so comparisons will be made with the previous model predictions for the same rated power setting at sea level.

Results are shown in Table 3. With the model now established and with reasonable accuracy and trends being displayed, the next undertaking was to run simulations of the Nomad II at a cruise power setting at varying altitudes. The values for rated power shown in Fig. As can be seen, shaft power output is accurately represented. The model prediction shows slight discrepancy at rated power conditions but is quite accurate at cruise power settings.

This is shown in Figure The negative slopes to both the rated and cruising engine power ratios versus altitude show that the turbomachines contribution to the overall shaft power output increases with altitude. This is the main reason why compound cycle engines maintain high thermal efficiency as altitude increases. The effect is more noticeable at the cruise power settings. Further work is planned to validate all of the operating points from those shown in Figure 10 and to examine trends in various operating parameters to further refine the model.

Exploring the overall engine performance effects for variations in exhaust port timings, compression ratios, piston engine operating speeds, boost pressures, and turbine characteristics can now be readily and quickly determined. With the interest nowadays in aircraft piston engines that burn jet fuel, the writer feels that this compound engine cycle should be revisited.

A range now dominated by shaft power turbine aircraft engines is the — 1, bhp sized machines. Small shaft power turbines in this range are notorious for poor thermal efficiency but this is the area where the compound cycle excels. The compound engine will never match the turbine with regard to installed weight and size —its multiple advantages lie in lower fuel burn per power developed, lower initial first cost, lower operating costs, and less cost to overhaul. The weight increase could be largely offset by the less weight in fuel for a given mission.

The compound engine would use virtually half that of the turbine for the same power output. The technology now exists to build a modern version of the Nomad II with substantially better specific power output, and with equally attractive, low specific fuel consumption. Such an engine would be well-suited for numerous airplane and helicopter applications.

The ability to operate on turbine engine fuels is seen as a significant advantage. From this study, it appears that all published data on the Napier Nomad II engine is indeed valid and does not violate any thermodynamic bounds of piston or turbomachine operation, as modeled by typical methods listed in the references. A compound engine cycle offers attractive benefits in high specific power outputs combined with low specific fuel consumption.

The computer model created utilizes a closed-form solution for calculating trends in the performance capabilities of this type of compound engine. It should prove useful in the design of new machines and when compressor and turbine maps are furnished, will allow theoretical performance predictions to be made with accuracy, without the reliance on pre-obtained test data for model calibration. Even though extensive and successful testing was performed during the Nomad program, both in the laboratory and in flight via a converted Avro Lincoln bomber, the engine never made it to production status.

History shows that the Nomad was planned for release at a time when the turboprop and turbojet engines were already in service and had a firm foothold in the market [4]. The advantages of a highly fuel-efficient aircraft engine were just not a top priority at the time, thus canceling the project.

The Napier team is to be admired in the design and development of the Nomad II, especially so when the only engineering calculating device available at the time was the slide rule! Paul H. Gordon P. David has over 32 years of consecutive employment with five different major engine manufacturers. David holds seven patents in the internal combustion engine field, and is a member of the Society of Automotive Engineers and American Society of Mechanical Engineers.

Since retiring in David runs his own business, Kirk Engines, Inc. Send mail to with questions or comments about this web site. This website depends on cookies to make it function. If you continue to browse, scroll, click or otherwise interact, you are providing implicit acknowledgement of and agreement to this. Choice of the two-stroke engine operating cycle was also wise. This is especially true for a highly compounded engine cycle such as this.

For two identically similar piston engines incorporating the same displacements, shaft power outputs and operating rpm, the two-stroke offers several significant advantages over the four-stroke. This is due to double the firing frequency of the two-stroke which yields the following: Doubled firing frequency of the two-stroke means half the BMEP Brake Mean Effective Pressure is required for the same power output.

This reduces cylinder peak firing pressures and bearing loading when compared to the four-stroke. Lower cylinder peak pressures allow for a lighter engine structure, reducing engine mass. For the same power output under boosted conditions, the two-stroke cycle requires half the boost pressure requirement of the four-stroke, this being due to the BMEP being exactly half of the four-stroke. This reduced pressure can alleviate the need for an induction air intercooler, thus saving space and weight.

Offsetting this somewhat is the necessity of double the mass airflow demanded by the two-stroke, thus entailing use of a physically larger compressor. Absence of mechanical valves and valve actuation machinery results in a simpler, lighter and more compact engine. Doubled firing frequency results in reduced torsional stress on driven components plus a more uniform gas flow into the turbine. Notes: Numbered points in Table 2 i. This discrepancy could be due to test data reflecting adiabatic efficiency versus actual efficiency.

Model set for same pressure ratio as stated in data. Model predicts excellent agreement with compressor discharge pressure. Model predicts excellent agreement with compressor discharge temperature. Scavenge air pressure is the same as that given in 4. Scavenge air temperature is the same as that given in 5. This could be caused by no discharge pressure stated in test data, where in the model it is assumed to be at ambient pressure. Considered excellent agreement.

These output parameters were calibrated to be the same as test data by adjusting 1 , 2 , and Predicted power ratio agreement reflects adjustments stated in Model calculates that Notes: Numbered points in Table 3 i. Pressure ratio adjusted to match that stated in test data. This would signify that turbomachine is now operating at maximum rpm. Scavenge air pressure the same as compressor discharge pressure.

Scavenge air temperature the same as compressor discharge temperature. Pressure drop across cylinders is the same as scavenge air mass flow is unchanged from sea level conditions. Note that the predicted temperature of 1, This indicates that as altitude increases lower inlet air density conditions , the turbomachine contributes more power to the overall sum. Model predicts that BSFC remains unchanged.

Model predicts a very slight decline in thermal efficiency caused by Additionally, differing mass flow rates and pressure ratios would alter efficiencies of both compressor and turbine. It is assumed that the Beier transmission is optimally controlled such that at a given crankshaft speed and power output, the turbomachine is delivering an optimal power contribution via its speed relationship to the crankshaft. This compensates for the unknown compressor speed and efficiency data.

The maximum pressure ratio to not exceed 8. Check that compressor volumetric flow rate matches that of the piston engine. If out of bounds, recalculate 2 and compare. Compare predicted BSFC value to test value. If not in reasonable agreement, go to 1 and repeat calculation. Calculation rejected if endless loop occurs or output values are outside of the range of realistic and logical values. Some of the additional predicted information of importance is mentioned: Cruise power is stated as a crankshaft speed of 1, rpm.

From a propeller load curve 3rd order approximation based on 3, rated SHP 2, rpm , this is a Из далеких гондол движки Merlin предполагалось удалить, установив там топливные баки. Эта конфигурация обязана была послужить для тестирования Nomad II и, в перспективе, установления рекорда дальности полётов. Расчёты демонстрировали, что самолёт сумеет на высоте наиболее метров преодолеть расстояние км.

Вообщем, для экипажа в негерметичной кабине это было нереально, потому разглядывали и вариант полёта на в два раза наименьшей высоте на дальность км. Доработанная модификация Nomad II в году стабильно обеспечивала мощность л. Работы по созданию очень экономичного авиадвигателя, на которые в сумме ушло 5,1 миллиона фунтов стерлингов, были совсем свёрнуты в апреле года.

Движок Nomad II можно узреть в авиамузее при Вашингтонском международном аэропорте имени Даллеса шт. За прошедшие с тех пор 70 лет газовые турбины ушли далековато вперёд в технологическом плане, но мысль совмещения дизельного и обычного турбинного движков заслуживает внимания и сейчас — на этот раз в целях действенной распределённой электрогенерации. Napier Nomad II. Теги: Napier двигателестроение двигателестроение Англии моторостроение моторостроение Англии 1-ые реактивные.

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