Single engine climb at V2 or Vref ?

[Dariuszw]

Has any one of you noticed this phenomena that when taking off soon after rotation Vref becomes higher then V2. That's the case at least in Citation. Its a bit problematic since in case of single engine climb below 1500ft V2 is expected to be mainteined. I do not think Cessna expects me to fly below Vref ..... I would in such case increase the speed to Vref and fly that instead of V2. Any idea why Vref increases so quick ???

[SloppyJoe]

Your a 17 year old citation pilot and one of your interests is flight sims?

And this gem from a previous post

Question:

I understand we reduce thrust due to warmer then standard temps or higher then standard density altitude in order to limit I guess ITT and preserve this way engine life. But N1 is reduced also when temp are colder then standard. Is it because of stractural limits or what.... ??

There is nothing wrong with asking questions but pretending to be a citation pilot is a bit weird.

[MarkerInbound]

Ah, Vref=Reference LANDING speed, V2=TAKEOFF safety speed.

The technical answer is V2 protects you to a 30 degree bank, Vref protects you to 40. Yes, Cessna in this case expects you to fly your CLIMBOUT at a lower speed that you would fly your APPROACH. Cessna would not expect you to maneuver as radically on takeoff as on landing.

[Dariuszw]

Disagree, Vref has nothing to do with approach speed during climb out as it simply represents 1.3 of stall speed and is represented by green donut during takeoffs and landing. I'm sure Cessna does not want me to fly below 1.3 stall speed... right ? No jet should be flown below 1.3 stall speed. I cant believe there is not even one person who noticed that as well and can explain it. So perhaps someone can just tell me why Vref increases so quickly and please avoid ground effect explenation as the increase starts well above ground effect alitutde.

Sloppy - when you will have half of my knowledge at 40 then perhaps you'll get to fly sport car as well and for now go back to your 737 bus and fly your freight :cool:

[bingofuel]

DariusZw

Would you care to explain your understanding of 1.3 x stall speed and how that reflects on the configuration of an aircraft?

[Brian Abraham]

Gents, Dariuszw is a Walter Mitty who started off under the user name SSG, and has had about a dozen incarnations since. Claims to fly a Citation Ultra and has a disposition to flail anyone with real experience, such as mutt or Galaxy Flyer. Favourite subject is advocating rejecting after V1.

[mutt]

No jet should be flown below 1.3 stall speed Are you sure about that? Look at some of the newer jets and see if they are using 1.3 Vs, or are they using 1.3 Vs1G, or are they using 1.23 vs or 1.23 Vs1G.......

I presume that you do know what Vs1G is?

[Dariuszw]

Mutt, perhaps that's true, I have not flown in my SIM ;) other jets then CJ so my statement is perhaps too broad. Nonetheless Citation is providing me with a green donut throughout my flight envelop on my Collins Proline PFD which it claims to be Vref of 1.3 Vs. So let me correct my statement: " No jet should be flying below Vref...right ? " Now, has anyone noticed what I have noticed ? Am I correct to assume Vref as minimum speed instead of V2 in such situation ? and does anyone have a clue as to why Vref increases so quickly above V2 ???

[Cough]

Darius,

Mutt provided a real clue there... I suggest more homework...

[Pugilistic Animus]

Ssg, you've become a fixture:}

[Brian Abraham]

when you will have half of my knowledge at 40Half of zero is still zero.

[galaxy flyer]

Brian

You're an optimist!

BTW, not President Bush posting elsewhere hereabouts.

[Pugilistic Animus]

SSG I think I know who you had at CAE for the Citation course Ms. Tooey -Currently Mrs. Hollaway-' Cuz you sure do talk a whole lotta hooey, but I must admit you're a riot, a real riot....:}:}:}

The Honeymooners - Hero - YouTube
skip to 18:00 -a classic episode indeed:ok:

:}:}:}

[Dariuszw]

Thanks P...Animus :E I know.

[Wizofoz]

Darius,

If V2 was your safety speed at rotation, how is it you you thnk it suddenly becomes unsafe once you are airborne?

Try reading up the definitions of those speeds- that might help....

[Pugilistic Animus]

Vref is final approach speed, V2 takeoof safety speed....Apples and Oranges--- different max weights different certification criteria different phases of flight....:cool:

[Intruder]

However, Vref and V2 are VERY close at a given weight (at least in the 747), so V2 can successfully be used in place of Vref in the case of an immediate emergency return for landing, if there's no time to get into the books.

[mutt]

In the L1011, VREF was used on takeoff as a Fuel Dumping limitation with Flaps 04, so as others have stated, they are extremely similar but based on different certification criteria.

(I miss 411A whenever i mention the L1011 :{)

[Dariuszw]

Im quite surprised that none of you know what Im talking about. Perhaps due to different avionic systems. But then let me ask you this: how do you know whats your 1.3 or 1.23 vs so called Vref during cruise ? After all you have not yet set up landing speeds yet. In CJ Vref is represented by green donut computed by computer and displayed entire time from start to land. V2 is taken from charts and is fixed. And when during takeoff Vref rises above V2 I assume Vref as minimum speed to fly and no longer V2. I think this might be CJ thing only so will adress this somewhere else. Ether way thank you for your answers !

[mutt]

Are you talking about all engine takeoff or engine failure on takeoff? If engine failure, then surely the concept is to fly V2-V2+10 until flap retraction altitude then accelerate to VFS followed by VSE?

We have the Vref for the present configuration available to us at all times, but as we have stated to you, it doesnt figure in our takeoff mentality.

[galaxy flyer]

Airbii have "green dot" speed in the PFD, also

Mutt

Funny thing, one didn't need to mention the L-1011 TrStar to have 411A bring the thread around to the L1011. Haven't checked, but I'll bet he could get the L10 into a thread about Pitts Specials.

[Intruder]

Im quite surprised that none of you know what Im talking about.
I'm not. You claim to "know" things about a SIMULATION of a particular airplane, but have no real knowledge of the reality of flying large and/or complex airplanes. Those of us who fly airplanes for a living realize that there are often [not-so-] subtle differences between regulation/certification, display in the cockpit, and real-time use of all that information.

On takeoff and initial climb, we use V2 and don't explicitly worry about Vref. The exception is an immediate return; and as I explained earlier, V2 is a reasonable replacement for Vref in that case. In cruise, we don't worry about either one. On descent, approach, and landing we worry about Vref and not V2. While we "know" in the back of our minds what kind of protections we are given by each number, we don't worry about the specifics real-time.

[Junkflyer]

V2 is not a fixed speed it varies with weight, between take off and landing you will burn a significant amount of fuel (weight) so vref will be determined by landing weight. V2 is not a factor during landing as previously stated. Cruise speed is typically a mach number (unless flying at a low altitude) based on weight and altitude and temperature and is not a fixed number. High speed/low speed buffet limits and g protection come into play here. I think you are trying to simplify something which is not always so simple.

[formulaben]

And when during takeoff Vref rises above V2 I assume Vref as minimum speed to fly and no longer V2.

Does this happen when you retract the flaps after takeoff?

[Dariuszw]

No, it happens below 1500' as we continue takeoff with simulated engine out well above ground effect and after gear up. So no configuration changes take place at that time. Cessna advises to climb at V2 which is set on the ground based on field elevation and weight but does not take into consideration increasing altitude during climb out. It cought me by surprise as to how quicly Vref climbs over V2 and Im not sure as to why but Im quite convinced I should not fly below Vref as its constantly recomputed and adjusted by FMS.

[mutt]

V2 is 1.13 times Vs1G (1.2 Vs) while VREF is 1.23 times Vs1G (1.3 Vs), so as you are talking about the same configuration on takeoff, would you not expect the Vref to be higher?

Your error is that you now think you should fly this higher speed, but have you considered that if you continue to chase the Vref speed, what is going to happen to your climb gradient? What happens to your 35 feet clearance over the obstacles?

[framer]

It´s such a silly question that I wouldn't have even thought it worth answering yet we have two pages on it.....crazy. It is like asking ¨How come the manufacturer of my car suggests using th foot pedal brakes while driving yet suggests using the park brake when stopped on a hill?....surely they don't want me to not use the foot pedal?¨ It just shows a complete lack of understanding of driving a car.

[de facto]

Guys ,we all know this darius is having fun using your time ....
Let him be ..:cool:

[Dariuszw]

Well ladies, I really would hate to waste your time and as some of you already know me, Im a gambling person. So here is your big chance to prove yourself. Care to put some money that what Im stateting is pure nonesense ???? Im in EDDL right ´now and have two more flights tonight on my .....SIM yet so when I get back home tonight I will accept any of your bets and then I will post pictures from my last flight proving it true. Till then...

Lets see if de Facto will be the first here to bet with this foolish 17 year old Darius ;-)

[SloppyJoe]

Well if your are telling the truth well done on having a total lack of understanding and putting your passengers at risk. Surely you should know this before you get in the plane. Chasing an increasing speed with an engine failing at V1, you truly are an incompetent fool.

[Cough]

Darius,

What we are saying to you is:

We know what you are observing is correct, that your V2 is lower than your Vref.

V2 and Vref aren't the same, don't treat them the same....

[de facto]

Im not sure as to why but Im quite convinced I should not fly below Vref

Convinced about something you are not sure huh..?
I suggest before this mentality kills you and your pax that you follow your sops/aircraft training manual.

Is that true your pax pay big money to be flown by you?:eek:

[Dariuszw]

http://dariuszwielgat.com/Foto.jpgSince I will not address each and everyone of those you know what....Let this be a lesson to all the rest of you ! There are many who will spew nonesense all day long here insulting others but when told to put weight behind what they spew none will have the guts ! So if u cant put money where your mouth is then you are just static, irrelevent, wasted time !



Mutt - You are absolutely correct. V2 is 1.2Vs and as such should be in theory less then Vref. My incorrect thinking was that I always assumed V2 to be equivalent to Vxse ( best angle of climb with single engine) which should be at or above Vref and that is not correct. V2 is minimum flying speed and is less then Vxse. That would explain Vref climb above V2 but why then it starts about 10kts below V2 hmm... ?

Mutt to aswer your question -what would happen to my climb performance and gradient if I increase my speed above V2 (up to some point) - I would answer that my climb performance and gradient will increase since V2 is not a performance limiting speed (like Vxse or Vyse)but mere minimum allowed flying speed with single engine. Do you disagree ?

Feel free guys to explain how your logic fits to this picture....be my guest !:}

[formulaben]

Quite simple: your V2 bug is a fixed bug, meaning it is calculated and then fixed to the airspeed tape. Your Vref bug is AoA CALCULATED...if in anything other than stabilized flight (accelerated flight) and IT WILL MOVE. Also, those bugs are usually FLAP COMPENSATED...I see you are 270 feet off the ground. Did you do a flaps 0 takeoff?

[gorter]

Taking pictures when you're operating 270' off the ground. Genius idea :ugh:

[Herod]

This guy is giving us MSFS pilots a bad name! :8

[Brian Abraham]

There are many who will spew nonesense all day long here insulting others but when told to put weight behind what they spew none will have the guts ! So if u cant put money where your mouth is then you are just static, irrelevent, wasted time Yep, that describes you to a T.

[Dariuszw]

formulaben - It was 15 degrees of flaps t/o all the way to 1500ft but perhaps your explenation could be correct as FMS might have a delay due to continued acceleration which can be seen by trend indicator. This film has been taken by colique of mine for maintenance consultation and comparison to other aircrafts in our fleet. I like your explenation and I think you might be right on the money :ok: Thank you !

One more thing that is a bit confusing for me is: V2.
Since V2 according to what I read is not Vxse but rather minimum flying speed with single engine then what is Vxse and why Cessna adiveses to maintain V2 instead of Vxse which could be Im guessing here V2+10 ?

[Herod]

Why don't you ask them?

[formulaben]

It was 15 degrees of flaps t/o all the way to 1500ft but perhaps your explenation could be correct as FMS might have a delay due to continued acceleration which can be seen by trend indicator.

No delay, real-time 1.3 Vs which changes with flap setting (you do know that, don't you?!) Flaps go up, your Vref bug goes up...do a flaps zero takeoff and it will be above V2.

[nizzy123]

i have read this thread and thanks to Mutt, Formulaben and moreso Darius for asking that question.Being a young and inexperienced pilot, i learn from people who ask questions n those who answer them genuinely. Experience is nothing here if all you do is rant about others.

[mutt]

V2 instead of Vxse which could be Im guessing here V2+10 ? We took off at MTOW, difference between V2 and VSE was 35 kts, certainly not 10.

The next question is when am i going to use that VSE speed? Any ideas Dariuszw? What did they teach you for the CJ?

Mutt

[Dariuszw]

Mutt - Difference between my V2 and Vt is 23kts so V2 and Vxse could not be nearly as much as your bus :rolleyes:. How much I would like to know myself since I cant find Vxse anywhere.

Now, to answer your patronizing question:

My idea of speed use in case of SE was until recently this: rotate, fly V2 (which I thought to be my Vxse.....NOT!), at 1500' fly Venr (Vyse).

Now, Mutt its your turn to shine and explain why I should fly V2 - like Cessna recommends - instead of Vxse till 1500ft. I would rather use best angle of climb till 1500ft for obsticle clearance rather then minimum flying speed. So what say you ....

formulaben - Not so fast, If you read my posts carefully you would see I that I said Vref accelerates above V2 way before I reach flap retraction height of 1500ft. Five seconds later Vref was about 10kts above V2 and flaps have not yet moved an inch.Thats why I believe speed acceleration had something to do here. Look at this picture here...

http://dariuszwielgat.com/Foto2.jpg

[mutt]

I would rather use best angle of climb till 1500ft for obsticle clearance Hey go ahead and use it, considering that you dont appear to be analyzing obstacles in the takeoff, you wont actually have to be concerned about hitting a close-in obstacle until its too late........

But for those operators who do analyze obstacles, they will discover that the air-distance required to accelerate will mean that they cannot clear the close-in obstacles, so that's why people keep advising you to use V2/V2+10.

Mutt

[Tinstaafl]

Dariuszw, V2 isn't necessarily a best angle of climb speed. It's a scheduled speed that, if followed, will enable the aircraft to meet the performance shown in the performance charts. Those charts account for the various regulatory requirements, including obstacle clearance at various distances from the take-off point.

Accelerating from V2 to Vx doesn't happen instantly. Nor is it 'free' ie there is a performance penalty during the acceleration phase. In this case, angle of climb. During that *short term* reduction in climb angle the aircraft may no longer meet the net climb gradient that obstacles or the rules require. You are correct in the sense that Vx will provide better climb angle than V2, however *getting* to Vx initially results in performance that may not meet the requirements.

There is a case where increasing speed can improve performance. Or, more usually, allow a greater take-off weight: Using an 'increased V2' or 'improved climb' or similar language. This is used to get a better climb angle to clear an obstacle further along the take-off path at the expense of using more runway & provided there aren't any limiting close in obstacles.