45

Jet fuel is mostly kerosene, with some aromatic hydrocarbons mixed in for stability, temperature range and the like. You could probably run military jets on pure kerosene if they were magically transported back to WWII, but you wouldn't have to as it would have been possible to make reasonable jet fuel. The Jet-A standard was made in the 50s, and there were ...


39

The most efficient IC engines are large Diesels. At the extreme end are ship engines with better than 50% thermal efficiency resulting in a specific fuel consumption of only 0.260 lbs/hp/hour or 158 g/kW-h. But even supercharged truck diesels achieve above 40% thermal efficiency at high load (this NHTSA study gives 42%). Aerodiesels have achieved 220 g/kW-h ...


38

They are both internal combustion engines that have a turbine in their exhaust that is used to power a compressor to pressurize the air before it is used for combustion. In the turboprop, the turbine also powers the prop. In between the compressor and turbine, the fuel/air mixture is burnt without significant moving parts. Without the turbine and ...


22

No, a turboprop is more like a jet engine with a propeller in the front instead of a fan: Source: Wikimedia In its simplest form a turboprop consists of an intake, compressor, combustor, turbine, and a propelling nozzle. Air is drawn into the intake and compressed by the compressor. Many turbo props have a gear box (as shown in the image above, the ...


10

Hydrocarbon cuts that can be used for jet fuel were plentiful during WWII; it was gasoline, especially high octane avgas, that was in short supply. Greatly over-simplified: the first stage in a refinery is the pipe still which boils the oil, then condenses it into different fractions according to temperature ranges. Typically a large fraction is "gas-oil" ...


9

How does turbine efficiency compare with internal combustion engines if all the turbine power is converted to mechanical energy? When looking at conversion from chemical energy into mechanical energy: very favourably. The early turbojets had low thrust efficiency, they could not convert their gas generator power into thrust in an efficient way. When ...


8

The term, hotel mode would be powering all non-propulsion electrical loads on an airplane using the power generating capabilities of the airplane, such as an engine or an Auxiliary Power Unit (APU). The term comes from the maritime industry from the expression, hotel load. This is the electrical load for all non-propulsion systems on a ship. https://en....


8

My guess, and it's just a wild guess, is humidity based ice forming somewhere in the inlet and/or the inlet plenum, more or less similar to carburetor icing. The symmetrical torque drop is from the flow restriction and the random vibration is when the ice breaks up. I'll guess that you were flying though what appeared to be clear or clearish air with the ...


7

Either the starter generator isn't making the torque it should be making, or there is a fuel flow issue. If I was betting 10 bucks on the result, I'd go with weak starter/generator and swap it out if another was available, or do diagnostic testing on the unit like insulation resistance checks and other electrical tests on the motor. Regardless, if your ...


7

They are more like an aerobatic airplane that's flying upside down. The wing of the propeller blade keeps moving in the same direction but it just rotates so it operates at a negative angle of attack to make lift in the opposite direction from normal. The blade is in a socket in the hub that allows the blade to rotate on its long axis. The blade root has ...


5

A turbocharged engine is a common gas engine with pistons The limiting factor on a gas engine is how much air can get into the pistons. It is supercharged - that is, an air pump forces more air into the engine than it would draw naturally. The mechanically driven variety is seen on Mad Max. If you use exhaust flow to spin the pump, it is turbosupercharged. ...


3

Very well as the Carnot efficiency is what drives the theoretical limit, and that is driven by the temperature of the combustion. 1 - T_h/T_c (in Kelvin) Turbines have very hot combustion chambers (diesels too, gasoline less so (due to knocking)). So a turbine operating in cold air will have great performance. In electricity generation Natural Gas ...


3

Very poorly actually. What saves turboprops and turboshafts is power to weight, smoothness and reliability. If you want just maximum MPG and don't have to go trans sonic, recip wins hands down. Piston engine Specific Fuel Consumption is roughly .45 lbs/hp/hr for a normally aspirated carbureted engine (that figure comes from my own Lycoming engine's power ...


3

Yes it loads up the battery, but the battery is sized to do this. The generator is not necessarily sized to do this, especially on the ground, so this procedure gets you to take the generator out of the system for each start. On an Alternator, like on your car, there is a phenomenon known as 'forward-stripping', which is where there is such a demand for ...


3

You certainly can. The equivalent to overtorquing is called overboosting and is defined as an exceedance of the primary thrust setting parameter, N1 or EPR. Modern FADEC engines contain software protection, but it is certainly possible in mechanically controlled engines. Thus, older aircraft, such as the DC-9 have mechanical or electronic controls which set ...


3

The reason a Diesel engine has a torque figure and a horsepower power figure is because max torque and max horsepower occur at different engine RPMs. Have a look at any performance curves of a piston engine and this will be evident. Hence, to define in a few numbers the maximum performance of the engine, you need to give both figures. However, turboprop ...


3

Turboprops are more efficient, because they accelerate more air by less to create the thrust, and therefore the air carries away less energy , since kinetic energy is proportional to square of velocity. This is true at all altitudes. Neither engine benefits from altitude. They do benefit somewhat from the colder temperatures up high as heat engine ...


3

They are completely different things, a turboprop is similar to a jet engine as it has compressors, the main difference is that there's a shaft that spins a propeller instead of turning a fan. A turbocharger is device for piston engines, it uses pressure coming from the exhaust manifold of a piston engine to compress air going into the intake manifold. It'...


2

Large airliners don't fly at slower speeds. It's simple economics. If you have to connect two destinations 10,000 miles apart, you'll do maybe 2 round trips a week. Your passengers have no other choice, except a flight that takes even longer. You also have the luxury of flying between two very large cities. If you have to connect two destinations 100 ...


2

No, one is https://en.wikipedia.org/wiki/Otto_cycle one is https://en.wikipedia.org/wiki/Brayton_cycle, thermodynamicly extremely different


1

As stage lengths decrease, maximum cruise speed at 39,000 feet plays a diminishing role in determining gate-to-gate durations since there usually isn't enough time to climb to that altitude and then descend again on a commuter hop. This means that there is a viable flight profile that involves a climb to a lower altitude and a lower speed cruise which ...


1

A feathered propeller is designed not to windmill in flight, however in the case of a power turbine or even a propeller connected to both the compressor and turbine, it's far easier to turn than an old radial when in the feathered position. Nothing physically stops the propeller from turning when feathered beyond the force required to turn the power ...


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