Equivalent shaft horsepower - aircraft maintenance , Other Engineering

Assignment Help:

Equivalent Shaft Horsepower (EHP)

In practice there is always a certain amount of jet thrust in the total output of the turbo-propeller engine and this must be added to the s.h.p. The correction for jet thrust is the same as that specified earlier.

To distinguish between these two aspects of the power output, it is usual to refer to them as s.h.p. and thrust horse-power (t.h.p.). The total equivalent horse-power is denoted by t.e.h.p. (sometimes e.h.p.) and is the s.h.p. plus the s.h.p. equivalent to the net jet thrust. For estimation purposes it is taken that, under sea-level static conditions, one s.h.p. is equivalent to approximately 2.6 lb. of jet thrust. Therefore:

t.e.h.p. = s.h.p. +jetthrust lb/2.6

The ratio of jet thrust to shaft power is influenced by many factors. For instance, the higher the aircraft operating speed the larger may be the required proportion of total output in the form of jet thrust. Alternatively, an extra turbine stage may be required if more than a certain proportion of the total power is to be provided at the shaft. In general, turbo-propeller aircraft provide one pound of thrust for every 3.5 h.p. to 5 h.p.

COMPARISON BETWEEN THRUST AND HORSE-POWER

Because the turbo-jet engine is rated in thrust and the turbo-propeller engine in s.h.p., no direct comparison between the two can be made without a power conversion factor. However, since the turbo-propeller engine receives its thrust mainly from the propeller, a comparison can be made by converting the horse-power developed by the engine to thrust or the thrust developed by the turbo-jet engine to t.h.p.; that is, by converting work to force or force to work. For this purpose, it is necessary to take into account the speed of the aircraft.
t.h.p. is expressed as FV/550 ft. per sec

Where F = lb of thrust
V = aircraft speed (ft. per sec)

Since one horse-power is equal to 550ft.lb. per sec. and 550 ft. per sec. is equivalent to 375 miles per hour, it can be seen from the above formula that one lb. of thrust equals one t.h.p. at 375 m.p.h. It is also common to quote the speed in knots (nautical miles per hour); one knot is equal to 1.1515 m.p.h. or one pound of thrust is equal to one t.h.p. at 325 knots.

Thus if a turbo-jet engine produces 5,000 lb. of net thrust at an aircraft speed of 600 m.p.h. the t.h.p. would be 5000*600/375 = 8000

However, if the same thrust was being produced by a turbo-propeller engine with a propeller efficiency of 55 percent at the same flight speed of 600 m.p.h., then the t.h.p. would be: 8000*100*/55 = 14545

Thus at 600 m.p.h. one lb. of thrust is the equivalent of about 3 t.h.p.

 


Related Discussions:- Equivalent shaft horsepower - aircraft maintenance

Engine, #question.what if i poured diesel in petrol engine and petrol in di...

#question.what if i poured diesel in petrol engine and petrol in diesel engine.

Dsp, relationship between z plane and s plane in bilinear transformation me...

relationship between z plane and s plane in bilinear transformation method

Image orthicon camera tube, What are the disadvantages of Image Orthicon Ca...

What are the disadvantages of Image Orthicon Camera tube

Numericalle.., The Stefan-Boltzmann law can be employed to estimate the rat...

The Stefan-Boltzmann law can be employed to estimate the rate of radiation of energy H from a surface of copper sphere with radius = 0.15 ±0.01 m, as in H=AesT^4 where H is in watt

Bragg''s spectrometer , It consists o a source of x ray, with a number of c...

It consists o a source of x ray, with a number of collimated slits. Crystal under investigation is mounted on a table, and the position of this table can be recorded on vernier sca

Finance.., hi, I need to do this question but I couldn''t capable to do i...

hi, I need to do this question but I couldn''t capable to do it. so can you tell me how much money I can give you to be done? How would you value the price of a Microfinance I

Case study, M/s XYZ Ltd manufactures a product “PLVS” at its plant at Meeru...

M/s XYZ Ltd manufactures a product “PLVS” at its plant at Meerut, the maximum capacity of which is 200 units per month. Details of raw materials which go into the making of 1 units

Homework, 1) An investment project requires a net investment of $100,000. T...

1) An investment project requires a net investment of $100,000. The project is expected to generate annual net cash flows of $28,000 for the next 5 years. The firm''''s cost of cap

Welding, what is causes of submage arc welding

what is causes of submage arc welding

Switching, name the switching schemes used in a digital exchange. how call ...

name the switching schemes used in a digital exchange. how call processing takes place?

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd