PDA

View Full Version : what does V mean in V rotate,V speed,V1,V2 etc?



Top_Gun_1_0_1
06-12-2006, 09:48 PM
commercial jet thing eh ..... please help....

TY http://forums.ubi.com/images/smilies/25.gif

Top_Gun_1_0_1
06-12-2006, 09:48 PM
commercial jet thing eh ..... please help....

TY http://forums.ubi.com/images/smilies/25.gif

NonWonderDog
06-12-2006, 09:50 PM
Velocity.

Indicated Air Speed, really.

Top_Gun_1_0_1
06-12-2006, 09:52 PM
ooooops http://forums.ubi.com/images/smilies/16x16_smiley-indifferent.gif....ty

how about the N in N1,N2 of jets ENG.?

tHeBaLrOgRoCkS
06-12-2006, 10:08 PM
Umm Number 1, Number 2, ?

Targ
06-12-2006, 10:13 PM
Bugs set...

Top_Gun_1_0_1
06-12-2006, 10:15 PM
each engines has n1 n2 rpm
but dunno wat N means http://forums.ubi.com/images/smilies/16x16_smiley-indifferent.gif

Targ
06-12-2006, 10:48 PM
N1 is the low engine pressure compressor and N2 is the high engine compressor gauge.
They are gauges used with the epr in an emacs seen on glass cockpits.
Measures engine compression in and out and is dispalyed as a percentage IE 80% or 120% of engine power.
You can set the computer to use EPR and unless the computer glitches it will control the takeoff for you. Fed ex MD-11's are all epr take offs.
Pilot sets the epr and has his hands on his knees in case he needs to manually take control (the epr fails)and watches the N1, N2 ,EGT and FF during take off to make sure they are not to low.
I have only jumpseated on Fed-ex planes a few time so I dont really understand exactly how auto thrust airplanes work (just a basic understanding) as most of the cockpits I have flown were not built before the 70's http://forums.ubi.com/images/smilies/16x16_smiley-very-happy.gif

WTE_Galway
06-13-2006, 01:25 AM
most of the "V"s are in this list:

http://www.gps.tc.faa.gov/glossary.html

watch out for Vne http://forums.ubi.com/groupee_common/emoticons/icon_smile.gif

BfHeFwMe
06-13-2006, 01:55 AM
N1 is your fan assembly, N2 is your compression section, the fan assembly is for bypass thrust with much of the air never entering the engine. Why they're called Turbo'fan's. Each fan section can be on it's own shaft in more modern engines.

Engine pressure ratio is measured forward and aft of the N2 section, that being one of the measures of the power being produced. The other is EGT, exhaust gas temp, a probe gives a reading right behind the hot section turbine.

rnzoli
06-13-2006, 02:18 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">the N in N1,N2 </div></BLOCKQUOTE>

IMV-VHO, N means "Nominal". 100% is the rated engine power, which you exceed only during special situations for a limited time, like take-off or go-around.

Capt.LoneRanger
06-13-2006, 02:22 AM
V1 and V2 means "Vergeltungswaffe" (revenge weapon) - uit has nothing to do with the other Vs.

btw. V0 is the start-velocity, e.g. of a bullet at the time it leaves the muzzle.

joeap
06-13-2006, 05:23 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Capt.LoneRanger:
V1 and V2 means "Vergeltungswaffe" (revenge weapon) - uit has nothing to do with the other Vs.

btw. V0 is the start-velocity, e.g. of a bullet at the time it leaves the muzzle. </div></BLOCKQUOTE>

No it also means this:
V defenitions (http://www.gps.tc.faa.gov/glossary.html#sectV)

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">
Vl Critical Engine Failure Velocity (Takeoff Decision Speed)

V2 Takeoff Climb Velocity
</div></BLOCKQUOTE>

Top_Gun_1_0_1
06-13-2006, 11:16 AM
how much is d 747s Gs during t/o?
gives me an headache http://forums.ubi.com/images/smilies/35.gif

but it was fun!

Capt.LoneRanger
06-13-2006, 11:39 AM
Sure. It could also describe 2 seperate vectors shaping a third one. http://forums.ubi.com/images/smilies/16x16_smiley-happy.gif

Sillius_Sodus
06-13-2006, 01:01 PM
Depending on the engine manufacturer, takeoff thrust is set by reference to EPR or N1 values.

Sillius_Sodus

darkhorizon11
06-13-2006, 02:49 PM
Without going into extensive detail about jet engine physics...

Most turbofan and turbojet engines have two spinning shafts, one spins inside the shorter shaft and pokes out on each end.

The inner shaft is the N1 shaft and has the intake turbine (or the fan on a turbofan) attached on the front end and the rear low pressure turbine on the opposite end. This entire system (shafts and turbines) is called the N1 assembly.

The outer N2 shaft that is shorter holds the compressor and ussually has a high pressure turbine behind it. This whole assemby is called N2.

N2 ussually spins much faster than N1, on the CF-34 turbofan the N2 shaft maxes out at like 17000 RPM.

Like any recip engine these shafts have their limitations and can't be operated passed a certain RPM. Generally though RPM isn't shown on the display its actually shown as a percentage, 100% being maximum available power.

Taylortony
06-13-2006, 11:11 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by darkhorizon11:
Without going into extensive detail about jet engine physics...

Most turbofan and turbojet engines have two spinning shafts, one spins inside the shorter shaft and pokes out on each end.

The inner shaft is the N1 shaft and has the intake turbine (or the fan on a turbofan) attached on the front end and the rear low pressure turbine on the opposite end. This entire system (shafts and turbines) is called the N1 assembly.

The outer N2 shaft that is shorter holds the compressor and ussually has a high pressure turbine behind it. This whole assemby is called N2.

N2 ussually spins much faster than N1, on the CF-34 turbofan the N2 shaft maxes out at like 17000 RPM.

Like any recip engine these shafts have their limitations and can't be operated passed a certain RPM. Generally though RPM isn't shown on the display its actually shown as a percentage, 100% being maximum available power. </div></BLOCKQUOTE>

To add to this, It is to do with efficency. A compressor blade works most efficently at just below the speed of sound. Therefore the tip rotational speed on a large blade is going to be faster than that of a small blade, so whilst the large blade rotating at near supersonic tip speeds is working at its best, the smaller blades behind it are working less efficently, it would in an ideal world be most effective to have each stage running at their own efficent speed, but this would intail having a single turbine stage for each compressor stage and the weight and complexity would be enormous, therfore you split the compressor at some point into 2 or 3 sections and run those at their most efficent. the RB 199 that powers the Tornado has a triple spool system, the centre one also rotating in the opposite direction to the other to to alleviate some of the torque issues... it is also not just high ration bypass engines such as the RB211 or trent that have this layont, most gas turbines are the same.

Taylortony
06-13-2006, 11:13 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Taylortony:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by darkhorizon11:
Without going into extensive detail about jet engine physics...

Most turbofan and turbojet engines have two spinning shafts, one spins inside the shorter shaft and pokes out on each end.

The inner shaft is the N1 shaft and has the intake turbine (or the fan on a turbofan) attached on the front end and the rear low pressure turbine on the opposite end. This entire system (shafts and turbines) is called the N1 assembly.

The outer N2 shaft that is shorter holds the compressor and ussually has a high pressure turbine behind it. This whole assemby is called N2.

N2 ussually spins much faster than N1, on the CF-34 turbofan the N2 shaft maxes out at like 17000 RPM.

Like any recip engine these shafts have their limitations and can't be operated passed a certain RPM. Generally though RPM isn't shown on the display its actually shown as a percentage, 100% being maximum available power. </div></BLOCKQUOTE>

To add to this, It is to do with efficency. A compressor blade works most efficently at just below the speed of sound. Therefore the tip rotational speed on a large blade is going to be faster than that of a small blade, so whilst the large blade rotating at near supersonic tip speeds is working at its best, the smaller blades behind it are working less efficently, it would in an ideal world be most effective to have each stage running at their own efficent speed, but this would intail having a single turbine stage for each compressor stage and the weight and complexity would be enormous, therfore you split the compressor at some point into 2 or 3 sections and run those at their most efficent. the RB 199 that powers the Tornado has a triple spool system, the centre one also rotating in the opposite direction to the other to to alleviate some of the torque issues... it is also not just high ration bypass engines such as the RB211 or trent that have this layout, most gas turbines are the same. </div></BLOCKQUOTE>