Venr, Vyse

[cezzna]

Posted this earlier, FSI is teaching that VENR is the same as VYSE, if nobody here can tell me the difference where should I look. I know that it's not right, just need the evidence.

 

[mazawakhan]

OK! WTF is Venr? In over ten years of flying I have yet to hear of that one!

 

[kevdog]

OK! WTF is Venr? In over ten years of flying I have yet to hear of that one!

In over 18 years of flying I have yet to hear of that one!

 

[asayankee]

In over 18 years of flying I have yet to hear of that one!

I'm going to go out on a limb and say it's the same as what a lot of people call Vt....best climb in a clean configuration. I hink it stands for V-enroute. Just guessing though.

 

[UndauntedFlyer]

I never heard of it either...

 

[charter dog]

I had never heard of Venr until I flew Hawkers. It is never really defined in the FSI Hawker training manuals as anything but a final OEI climb speed. Venr will only be about 186 KIAS for a MGTOW (28,000 lb) 800XP. The aircraft is to be flown at this speed after reaching 1,500' AGL or running out of time on the takeoff engine limits, cancelling APR and setting max continuous thrust on the remaining engine. In practice, the -5BR engines are nowhere near limiting temps or speeds so no reduction would normally be necessary. This is a certification profile of course and bears little resemblance to the profile that would actually be flown in IMC over anything but flat ground. Venr is a performance speed like V2, meaning it's primary purpose was to establish a OEI climb profile for certification and may or may not be intended to achieve max SE ROC. Since climb gradient is our primary concern following takeoff, we would not normally accelerate to this speed until clear of all obstacles if visual, or at the minimum required IFR altitude if not. In any case, Venr is just a bit more than 1.6 Vs and would be pretty close to Vyse if that term were used. For the fullest possible explanation, post this in the tech log at PPRuNe. Guaranteed to to get you more of an answer than you bargained for!

Best,

 

[CA1900]

We use it at CommutAir -- it's defined as the single-engine enroute climb speed. In the event of an engine failure on takeoff, we climb at V2 until 400 feet, accelerate to Venr, and then climb at that speed.

I suppose it could be the same speed in some airplanes, but it isn't in ours in most cases. For example, a fully-loaded 1900 would have a Venr of 123, while Vyse is 128. Definitely not the same speed.

 

[wmuflyguy]

I'm going to go out on a limb and say it's the same as what a lot of people call Vt....best climb in a clean configuration. I hink it stands for V-enroute. Just guessing though.

or Vfs

 

[Luxor Two]

Well I guess if UndauntedFlyer hasn't heard of it, then it truly does not exist.

His Airworthiness ladies and gentlemen.

 

[Metro752]

.............zippo

 

[Cardinal]

Ok, to prove your case, FSI should darn well have a Raytheon B1900D AFM in the building with their vaunted 1900 sim. Look up Venr for max gross, 17,120. Look up Vyse at sea level (decreases 2 knots / 5000 ft) at 17,120. Your two different answer (Venr 123, Vyse 128) WILL NOT MATCH. There is your evidence that it aint the same thing.

 

[52560]

I have been in that debate with FSI also. I pulled out a book that explained it very well (i can't remember the title), but the instructor said I was incorrect along with the book. Oh well....i guess that is why I am not the instructor

 

[JetDriver2727]

Venr

I think this was already addressed but I will take a second to re-state it. Venr is Enroute Climb Speed and is just another Name for Vfs or Vt. Cessna = Venr, Embraer = Vfs, Canadair = Vt, Boeing = Vfs. Bear in mind that the name of the specific "V" speeds above were used at the corporate and airline operators I have worked at, and your airline may have a different name for the same speed. In the 737, we use Vm (clean manuvering speed) as our Vfs/Venr/Vt in the event of an engine failure after takeoff and after cleanup. This is slightly faster then Vyse, but Vm is used to permit bank angles greater then 15 degrees.

V2 is not Venr!!! V2 = best rate of climb with the gear up and flaps in the takeoff position, and is the speed you will fly from a height 35 feet high after takeoff untill you achieve "acceleration height/altitude" or "cleanup height/altitude." After acceleration and cleanup, you will maintain Venr. Venr will provide you with a speed that will allow for a climb near Vyse (climb single engine in the CLEAN configuration, gear and flaps up for those that may have missed that.) Vfs/Vt/Venr, might be slightly above your Vyse speed to allow for manuvering (i.e. not limited to 15 degrees of bank) depending on the aircraft.

I am a pilot, not a writer. If the above doesn't make sense, then disregaurd it and go here: http://www.airplanedriver.net/study/part25.htm

 

[UndauntedFlyer]

I think this was already addressed but I will take a second to re-state it. Venr is Enroute Climb Speed and is just another Name for Vfs or Vt. Cessna = Venr, Embraer = Vfs, Canadair = Vt, Boeing = Vfs. Bear in mind that the name of the specific "V" speeds above were used at the corporate and airline operators I have worked at, and your airline may have a different name for the same speed. In the 737, we use Vm (clean manuvering speed) as our Vfs/Venr/Vt in the event of an engine failure after takeoff and after cleanup. This is slightly faster then Vyse, but Vm is used to permit bank angles greater then 15 degrees.

V2 is not Venr!!! V2 = best rate of climb with the gear up and flaps in the takeoff position, and is the speed you will fly from a height 35 feet high after takeoff untill you achieve "acceleration height/altitude" or "cleanup height/altitude." After acceleration and cleanup, you will maintain Venr. Venr will provide you with a speed that will allow for a climb near Vyse (climb single engine in the CLEAN configuration, gear and flaps up for those that may have missed that.) Vfs/Vt/Venr, might be slightly above your Vyse speed to allow for manuvering (i.e. not limited to 15 degrees of bank) depending on the aircraft.

I am a pilot, not a writer. If the above doesn't make sense, then disregaurd it and go here: http://www.airplanedriver.net/study/part25.htm

This all makes sense to me so it must be well written. Great Post.

I have one question though, this Venr speed is really just the clean maneuvering speed, which means it is also the Minimum Drag (L/D) Speed too, right? And then that would make it the best angle of climb speed, max endurance and approximately the best holding speed too. If that is what Venr speed is, then it is, of course, a most important speed by a different name than is used by Boeing, Douglass and others. Clean Maneuvering Speed always sounds familiar to everyone, it think.

OK then, the only thing I don't get in your post is why is it that you refer to this as an enroute climb speed? It seems that such a speed for enroute climb would be much faster than a clean maneuvering speed. For example in the 727 the clean maneuvering speed is around 200K to 210K and the enroute climb speed is typically 300K or more.

 

[MauleSkinner]

I have one question though, this Venr speed is really just the clean maneuvering speed, which means it is also the Minimum Drag (L/D) Speed too, right? And then that would make it the best angle of climb speed, max endurance and approximately the best holding speed too. If that is what Venr speed is, then it is, of course, a most important speed by a different name than is used by Boeing, Douglass and others. Clean Maneuvering Speed always sounds familiar to everyone, it think.

OK then, the only thing I don't get in your post is why is it that you refer to this as an enroute climb speed? It seems that such a speed for enroute climb would be much faster than a clean maneuvering speed. For example in the 727 the clean maneuvering speed is around 200K to 210K and the enroute climb speed is typically 300K or more.

Venr is Venr...it's the final segment climb speed in the Hawker...it is the equivalent of any V-speed that you use to climb once you're above obstacles.

at 25000 lbs, it's 176 kias...single-engine LRC (probably closer to best L/D) is 235. They also publish a "min cruise" speed of 206 for that weight.

As far as what FSI says, I've found it's best to take anything they say about performance with about a pound of salt...In over 10 years of FSI/Simuflite/Simcom training, I've run across 2 instructors who have a clue about it...although there is one guy who could probably build the airplane charts if he had to

Fly safe!

David

p.s...the other 4 answers I got are largely irrelevant, but the most common and consistent was "I don't know, and I don't care", or some variation thereof.

 

[User998]

Name for Vfs or Vt. Cessna = Venr, Embraer = Vfs, Canadair = Vt, Boeing = Vfs.

Minor correction here, Cessna (atleast the CJ2) displays Venr as Vt on the airspeed tape during takeoff.

 

[lawfly]

Venr,Vyse

V2 is not Venr!!! V2 = best rate of climb with the gear up and flaps in the takeoff position

A better analogy for V2 is best angle of climb speed with gear up, flaps takeoff, and takeoff thrust. It's all about the climb gradient. This is the 2nd segment of the climb, the 1st having ended with gear retraction/35 feet above runway, at V2. Indeed, the required minimum climb gradients for these segments is highest during the "V2 segment", i.e., during the second segment.

Venr is the target speed for the next segment, which involves flap retraction, reduction to max continuous thrust, and acceleration to Venr. This final segment generally begins at 400 agl.

I have not seen Vyse in the manuals for the Citation. While the rate of climb could be (is, I believe ) higher at Venr than at V2, the gradient is shallower because of the higher forward speed. I just looked at an FSI Citation handout, and Venr is defined therein as "Minimum Single Engine Enroute Climb Speed".
These are certification speeds in the event of an engine out scenario.
Vyse might be an okay analogy to Venr, although it would be just an analogy, as there is likely no published Vyse for the airplane, anyway.

 

[JetDriver2727]

It seems that such a speed for enroute climb would be much faster than a clean maneuvering speed. For example in the 727 the clean maneuvering speed is around 200K to 210K and the enroute climb speed is typically 300K or more.

Could it be that a 727 has 3 engines? I would be ventuing into an area I am not familiar with if I addressed this, but that would be my first guess. 2/3 engines remaining isn't too bad! Efficient climb speeds that are faster can be obtained with that much power remaining.

 

[JetDriver2727]

I have one question though, this Venr speed is really just the clean maneuvering speed, which means it is also the Minimum Drag (L/D) Speed too, right?

Remember that Venr is a speed determined during performance testing of an aircraft. It MAY or MAY NOT correspond to another speed such as clean manuvering, L/D max, or Vyse. Any similarity could be coincidental, or could be intentional depending on what the "Goal" of the manufacturer is.

 

[JetDriver2727]

Minor correction here, Cessna (atleast the CJ2) displays Venr as Vt on the airspeed tape during takeoff.

Details, Details...... Re read this:

Bear in mind that the name of the specific "V" speeds above were used at the corporate and airline operators I have worked at, and your airline may have a different name for the same speed.

I happened to fly the Cessna 560 (V) and we used Venr. The steam guage airspeed indicator can't display "Vt." I could see Cessna saving space on the speed tape on newer Citations by displaying Vt and opposed to Venr. In your quote above you say Venr is displayed as Vt on the speed tape, so it is still used to represent Venr, right? Whats it say in the flight manual? I bet it talks about Venr for enroute climb. Vt in most cases just means V target, and is arbitrary. One could argue that they use Vt to retract the ground spoilers after landing if they wanted. At my current airline, Vt is ref speed plus wind gust. To each his own...

 

[JetDriver2727]

A better analogy for V2 is best angle of climb speed with gear up, flaps takeoff, and takeoff thrust. It's all about the climb gradient. This is the 2nd segment of the climb, the 1st having ended with gear retraction/35 feet above runway, at V2. Indeed, the required minimum climb gradients for these segments is highest during the "V2 segment", i.e., during the second segment.

Venr is the target speed for the next segment, which involves flap retraction, reduction to max continuous thrust, and acceleration to Venr. This final segment generally begins at 400 agl.

I have not seen Vyse in the manuals for the Citation. While the rate of climb could be (is, I believe ) higher at Venr than at V2, the gradient is shallower because of the higher forward speed. I just looked at an FSI Citation handout, and Venr is defined therein as "Minimum Single Engine Enroute Climb Speed".
These are certification speeds in the event of an engine out scenario.
Vyse might be an okay analogy to Venr, although it would be just an analogy, as there is likely no published Vyse for the airplane, anyway.

You're right, I hastily left out the part about takeoff thrust, and even more carelessly I said V2 is best rate as opposed to best angle. Oops! even I make mistakes at 2:30 in the morning when I posted that.....But, I think everyine got the idea. You are correct that Venr provides for a higher climb rate, but shallower gradient then V2. I don't recall any Vyse speed being publised for any turbine powered part 25 airplane that I have flown so I agree with you there too. I have always been one to build analogies to keep things strait in my head, and I always remembered V2 as Vxse and Venr as Vyse. You are correct that it is only a loose analogy, but it helps visualize what you are trying to obtain with the aircraft.

 

[MauleSkinner]

As JetDriver2727 said, for the most part, jet performance numbers are not based on aerodynamic figures like Vx, Vy, etc.

Let's look at some specifics...

For the Hawker 800, at sea level, 22000 lbs, and 25 degrees C (numbers chosen out of pure laziness), V2 with flaps retracted is 133kias, and the chart shows a 6.2% net climb gradient. 6.2% of 135kTas, we end up with about 825 feet per minute.

Then, we look at Venr under these same conditions. Configuration is the same...the only difference is that we don't have APR activated, so thrust may be up to 2% less (I didn't think to check those numbers at the time). Venr at this weight is 154kias, and the chart yields a 6.4% net climb gradient. Boys and girls, that's a STEEPER climb, with LESS thrust. Working this further, we get a rate of about 985 feet per minute, again higher than the figure for V2. Obviously, V2 is NOT best angle for the configuration.

The reason for this is simple...it WILL climb at V2, and while it may not be at the best angle, accelerating to Vxse would require several miles of runway/clearway, which is generally not available. It's simply the best compromise for the situation.

Taking this a little farther, at this same weight, the Hawker Crew Manual gives a single-engine long range cruise speed of 220kias. There isn't a comparable chart for this operation, but theoretically, this SHOULD be roughly best L/D for the same configuration. Since the amount of lift produced doesn't change appreciably in an unaccelerated flight condition, and "thrust" being the counter to "drag", this is the "minimum thrust" speed...or the speed at which maximum EXCESS THRUST would be available. It's been a long time, but I think that's the definition of Vx...maximum excess thrust available. If my thought process is correct here, this would make Vxse more than 80 knots faster than V2. Imagine how much runway/clearway it would take to accelerate to 220kias in ground effect in order to make the best angle of climb...kinda kills any takeoff I've made

Note that, so far, the airplane has been in an identical configuration for each case...0 flaps, gear up, engine out...the only difference is possibly some extra thrust at V2.

I haven't looked at the case for jets, but in piston airplanes, Vy is always faster than Vx...I'm assuming the same is true for jets. This, to me, indicates that there is no way that Venr can be Vyse, because it would need to be faster than 220 knots.

I haven't got any reference for single-engine ops, but the climb profile for the 800 is 250kias until intercepting a mach number in the high 20's. Once we're above 10,000 we generally let the airplane accelerate (those airliners HATE being slowed to 250 behind us) to 270 or 280, and once stabilized, we actually get a higher climb rate than we do at 250. Again, the problem is that we climb so slowly while accelerating that we're altitude ahead to maintain 250.

Bottom line, Vx and Vy figures really aren't used in jets, or at least the ones I've flown...performance numbers are a simply a compromise built on the composite angle from "full power prior to brake release" to whatever altitude you're computing.

Fly safe!

David