The reason the military uses turbojets is because turbojets provide more power than turbofans can,
False. Nowadays military uses turbofans. Turbojet is no longer in use because performance is extremely low. However, military fighters use low derivation ratio turbofans because of compacity reasons.
The turbojet penalty is in the propulsion efficiency. To make thrust you need to accelerate a given mass flow. The thrust is Mass_flow*Delta_Speed, being Delta_speed the difference on flow speed from the engine exit respect the flight speed (unperturbed inlet speed). As a result there are two ways to produce high amounts of thurst:
a) Low Mass flow with high delta on speed
b) High Mass flow with low delta on speed
Turbojet does a) which is highly inefficient in energy terms (kinetic power transferred to the flow by the engine is 0.5*Mass_flow*(delta_speed)**2). (note that a**2 means a*a). Turbofan does b) providing same if not more thrust with lower energy involved. The highest derivation ratio the turbofan has, the better the propulsion efficiency is, and the larger the Fan radius is, also. Having large fans also involves transonic problems, and can become a problem for supersonic flights. As a result fighters use low derivation ratio turbofan because of compacity and perhaps because of supersonic flight requirement. Intake design may avoid supersonic problems in the fan, nevertheless- note how fighters have funny intakes in contrast to commercial airplanes. Also compare Concorde intakes to commercial transonic airplanes.
Yes, I know (I have a gmail account, too). However I wish they ofered also imap (having 1Gb storage I don't need copies of the email at my local hard drive... yes, I also know I can remove those copies once I have read the mail)
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False. Nowadays military uses turbofans. Turbojet is no longer in use because performance is extremely low. However, military fighters use low derivation ratio turbofans because of compacity reasons.
The turbojet penalty is in the propulsion efficiency. To make thrust you need to accelerate a given mass flow. The thrust is Mass_flow*Delta_Speed, being Delta_speed the difference on flow speed from the engine exit respect the flight speed (unperturbed inlet speed). As a result there are two ways to produce high amounts of thurst:
a) Low Mass flow with high delta on speed
b) High Mass flow with low delta on speed
Turbojet does a) which is highly inefficient in energy terms (kinetic power transferred to the flow by the engine is 0.5*Mass_flow*(delta_speed)**2). (note that a**2 means a*a). Turbofan does b) providing same if not more thrust with lower energy involved. The highest derivation ratio the turbofan has, the better the propulsion efficiency is, and the larger the Fan radius is, also. Having large fans also involves transonic problems, and can become a problem for supersonic flights. As a result fighters use low derivation ratio turbofan because of compacity and perhaps because of supersonic flight requirement. Intake design may avoid supersonic problems in the fan, nevertheless- note how fighters have funny intakes in contrast to commercial airplanes. Also compare Concorde intakes to commercial transonic airplanes.
oops, need to start again...:
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321.23 121.12
321.23 32.123
12.321
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last format: list io
lately reading direct formatted external IO
Aborted
you obviously forgot about pr0n
Do use xmag in linux, he he.
Outlook Web Access is the best webmail interface; it's practically the same as Outlook
You haven't tried gmail, have you?
Yes, I know (I have a gmail account, too). However I wish they ofered also imap (having 1Gb storage I don't need copies of the email at my local hard drive... yes, I also know I can remove those copies once I have read the mail)
Now there is a chance of gmail being available via IMAP any soon ;-))
btw, this is my first post as registered user!