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Bararontok
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Can somebody post a table of the average lift energy/thrust energy ratios or percentages of various types of aircraft?
Aero_UoP said:lift energy and thrust energy? with units of Joule ? Lift and thrust are forces...
Aero_UoP said:I'm afraid that unlike the wings, engines don't generate lift. They only produce thrust.
Now as for the energy, I think that what you need is the Specific Fuel Concumption. Maybe you can find the sfc for various engines on the internet.
russ_watters said:I don't see why l/d ratio isn't already the answer you are looking for...
...minus the already explained caveat that the question is meaningless as worded.
Aero_UoP said:Again, from what you say I think that what you need is the sfc of the engine.
http://www.grc.nasa.gov/WWW/k-12/airplane/sfc.html
L/D ratio is a percentage. As far as the engine knows, 100% of the energy/force generated goes to countering drag. But a certain percentage of that drag causes lift (yeah, a little sloppily conceived, but basically right...). That's the L/D ratio.Bararontok said:It is the answer I am looking for, I just wanted the values expressed as a percentage of the total power/energy used for lift versus the percentage used for forward thrust.
russ_watters said:As far as the engine knows, 100% of the energy/force generated goes to countering drag.
The Jericho said:I'm sure It's power to weight ratio that he wants... Weight = lift in straight and steady flight. Find the aircraft mass and max thrust and you get a ballpark figure.
If you want to get a more accurate figure you can find the NACA specs and get the coefficient of lift and by using the lift equation, find v when L = mg and this will tell you the velocity required to create lift equal to the aircraft mass. You can then use the thrust equation for to find calculate the required amount of thrust to maintain that velocity. Is that what you wanted?
Cheers,
The Jericho.
The Jericho said:I'm sure It's power to weight ratio that he wants... Weight = lift in straight and steady flight. Find the aircraft mass and max thrust and you get a ballpark figure.
If you want to get a more accurate figure you can find the NACA specs and get the coefficient of lift and by using the lift equation, find v when L = mg and this will tell you the velocity required to create lift equal to the aircraft mass. You can then use the thrust equation for to find calculate the required amount of thrust to maintain that velocity. Is that what you wanted?
Cheers,
The Jericho.
etudiant said:Thrust to weight has often been used as a simple metric to rate the agility of fighter aircraft. Over the years, this has crept up, from 0.2 for the early jets to over 1.0 for current designs. Of course, the measure is often inflated by the afterburner contribution, which yields great results for airshows, where fuel is not an issue.
Commercial jets usually run around 0.1-0.2, again overstated because take off thrust is only used for a minute or two and cruise thrust is usually only about 20% of that.
Is there any chance that you're looking for energy consumed due to induced drag (drag related to producing lift) versus energy consumed due to parasitic (drag related to profile, turbulence, friction, ...) drag?Bararontok said:Can somebody post a table of the average lift energy/thrust energy ratios or percentages of various types of aircraft?
rcgldr said:Is there any chance that you're looking for energy consumed due to induced drag (drag related to producing lift) versus energy consumed due to parasitic (drag related to profile, turbulence, friction, ...) drag?
Even for a specific aircraft the ratio of induced drag versus parasitic drag decreases as speed increases, and most powered air craft fly much faster than the ideal best glide ratio speed, which is the speed where ideally induced drag equals parasitic drag (meaning that induced drag is 1/2 of the total drag). At cruise speed, most of the energy is being consumed due to parasitic drag, not due to producing lift (induced drag).
So 10,000 feet of altitude and needing to travel 36,960 feet, a 2:1 glide ratio would be a problem here. Wiki lists the space shuttle glide ratio as 4.5:1 at subsonic speeds, 2:1 at supersonic speeds, and 1:1 at hypersonic speeds.etudiant said:glide ratio ... Space Shuttle at the low end at about 2:1. To put that into context, the Shuttle entered final approach at 10,000 ft, about 7 miles from touchdown.
The main source of energy for lift and thrust in aircraft is the engine, which converts fuel into mechanical energy. This energy is then used to power the propeller or turbine, which generates the necessary thrust to move the aircraft forward. The wings of the aircraft also play a crucial role in generating lift by creating a pressure difference between the top and bottom surfaces of the wing.
The amount of energy required for lift and thrust varies depending on the type and size of the aircraft. Larger and heavier aircraft typically require more energy to generate lift and thrust compared to smaller and lighter aircraft. Additionally, the design and aerodynamics of the aircraft also play a significant role in determining the amount of energy needed for lift and thrust.
No, the amount of energy used for lift and thrust can vary throughout different stages of flight. During takeoff, the aircraft requires a significant amount of energy to generate enough lift and thrust to become airborne. Once in flight, the amount of energy needed for lift and thrust decreases as the aircraft reaches its cruising altitude. During descent and landing, the aircraft will use less energy as it prepares to land.
Air density plays a crucial role in determining the amount of energy required for lift and thrust. In denser air, the aircraft can generate more lift and thrust with less energy, making takeoff and flight easier. However, in thinner air, such as at high altitudes, the aircraft will require more energy to generate the necessary lift and thrust, which can impact its performance.
Currently, most aircraft rely on traditional fossil fuels for energy to power lift and thrust. However, many researchers and engineers are exploring alternative sources of energy, such as electricity, solar power, and biofuels, to make aviation more sustainable. While there have been successful demonstrations of alternative energy sources in smaller aircraft, it may be some time before they are widely used in commercial aircraft due to technological and economic limitations.