V1 and light plane
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Dariuszw,
Thank you most sincerely for adding me to your ignore list, now that is indeed a compliment!
For the record before leaving this thread forever, yes, I do indeed accept it as truth that Jet aircraft at high altitude do indeed spend most of their time above Mcrit, even during climb. No, I don't believe it, belief is a matter of faith, I accept because it is FACT'
See you in the next incarnation.
Thank you most sincerely for adding me to your ignore list, now that is indeed a compliment!
For the record before leaving this thread forever, yes, I do indeed accept it as truth that Jet aircraft at high altitude do indeed spend most of their time above Mcrit, even during climb. No, I don't believe it, belief is a matter of faith, I accept because it is FACT'
See you in the next incarnation.
Dariuszw take a look here http://www.pprune.org/tech-log/40722...h-trimmer.html and don't confuse MMO and Mcrit.
You can also look here Mach Crit, Mach Number Buffet, Mach Tuck, and Mach Trimmers [Archive] - PPRuNe Forums May I suggest (if it's not too late) putting a request to Santa in for Handling the big jets?
You can also look here Mach Crit, Mach Number Buffet, Mach Tuck, and Mach Trimmers [Archive] - PPRuNe Forums May I suggest (if it's not too late) putting a request to Santa in for Handling the big jets?
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Old Smokey - As Im reading into this Mcrit business more and more I see that you might be correct. As we use Mmo and Mcrit is not a factor Im perhaps bit rusty on the subject. For now seems you are correct...but only for now and if I find something otherwise I will shove it back. But I do admit confusing it with something else. So ther you go
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V1 is always less then Vr. So explain that phenomena when takeoff is not ASDA limited ?
However I assure you there is no such place in US nor Europe where you cant descend to 10.000ft for more then two hours with jet speeds. Care to point one out
Believe it or not, there are even parts of the world where terrain can preclude decents below 10,000ft for periods longer than 30 minutes.
You are clearly arguing simply for the sake of arguing.
One point of confusion here--airlines are provided with more performance charts than are provided to business jet operators. The airlines have performance engineering departments that have all the "raw" charts--Vmcg, accelerate-stop, accelerate-go, brake energy limits, OEI climb gradients etc.
The AFM data provided business jet operators is "dumbed down" to presuppose every operation is a field length-limited take-off, that is only balanced field data only. We do not have all the charts to optimize performance because no operator wants to pay for it, to get trained in using them and to be legally responsible for any misuse. So, unless an operator uses a runway analysis provider, a lot of take-offs are done without all the facts, but the performance available is usually so much greater than the limiting case, it is not an issue.
To our fanatic poster, here's a suggestion. Go into the tab data, select the highest weight that the conditions will allow for take-off. IF the V1 for that weight is equal to or greater than Vr for your actual weight, your V1 can equal your Vr for the actual TOGW. You have "unbalanced" your field lengths i.e your actual accel-stop distance, based on the V1, will exceed your actual accel-go distance but both will be less than the TODA.
As to landing after rotate, you and the plane are much safer in the sky than trying to be a test pilot and landing again.
Call it the assumed weight method, but my heirs would appreciate if you don't reference me at the inquiry, if you overrun. BTW, I am pretty authoritative on the cost of providing performance engineering data prohibiting the provision thereof.
The AFM data provided business jet operators is "dumbed down" to presuppose every operation is a field length-limited take-off, that is only balanced field data only. We do not have all the charts to optimize performance because no operator wants to pay for it, to get trained in using them and to be legally responsible for any misuse. So, unless an operator uses a runway analysis provider, a lot of take-offs are done without all the facts, but the performance available is usually so much greater than the limiting case, it is not an issue.
To our fanatic poster, here's a suggestion. Go into the tab data, select the highest weight that the conditions will allow for take-off. IF the V1 for that weight is equal to or greater than Vr for your actual weight, your V1 can equal your Vr for the actual TOGW. You have "unbalanced" your field lengths i.e your actual accel-stop distance, based on the V1, will exceed your actual accel-go distance but both will be less than the TODA.
As to landing after rotate, you and the plane are much safer in the sky than trying to be a test pilot and landing again.
Call it the assumed weight method, but my heirs would appreciate if you don't reference me at the inquiry, if you overrun. BTW, I am pretty authoritative on the cost of providing performance engineering data prohibiting the provision thereof.
Blimey, this is hard work! Read again "Because V1 can't be greater than Vr - once yr past that, you're airborne and RTO is no longer an option. If you (knowing yr ac capabilities) decide that up to eg 50',100',200' whatever you plan to land back on straight ahead then that's a different matter"
I stick by that - if you are able to land back on and stop safely then why not? I guess you would probably have to initiate that before gear retraction.
The important thing is to make these decisions before you set off down the runway. So perhaps (not knowing yr aircraft type so doinbg a read across from my previous experience) the following might work (having considered the runway/weight/wx etc on the day) "up to rotate I shall carry out RTO iaw with our SOPs, after that before gear retraction I shall lower the nose and land on the rw remaining. Once the gear has started to retract I shall continue with the SID/carry out SOP EFATO actions whatever etc etc."
Hope this helps
I stick by that - if you are able to land back on and stop safely then why not? I guess you would probably have to initiate that before gear retraction.
The important thing is to make these decisions before you set off down the runway. So perhaps (not knowing yr aircraft type so doinbg a read across from my previous experience) the following might work (having considered the runway/weight/wx etc on the day) "up to rotate I shall carry out RTO iaw with our SOPs, after that before gear retraction I shall lower the nose and land on the rw remaining. Once the gear has started to retract I shall continue with the SID/carry out SOP EFATO actions whatever etc etc."
Hope this helps
Dariuszw: What makes you think that thye O2 requirements are only to cater for depressurisation? Do your drills not consider smoke scenarios?
PS I realise this may be a pointless post...................
PS I realise this may be a pointless post...................
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It is pointless. Because if you got smoke or fire you will land much quicker then when simple decompresion. It takes just two minutes from the moment you see first smoke to fully engulfed craft according to NASA studies. In all cases checklists will call for landing as soon as possible and not practical. If you argue that fire has been extinguished and only smoke persist you have cabin dump and fresh air options which will get rid of smoke. Hope that answers this question.
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Regarding Perf A & Bureaucratic regulation: You don't get the choice. Once the regulators get involved, you just have to comply. However, their involvement has forced some idiots to fly with fatter margins.
You can - that's your choice. But if you are flying an aircraft within its limitations it could mean you are legally in both IMC and icing conditions. So if you have a problem when just airborne, just how will you perform a safe land-ahead manoeuvre?
Yes - that is what you are paid to do. If you decide not, that's your choice. But don't ask for sympathy or understanding if you foul it up. I would also wish you the very best in stopping lawyers from climbing all over you.
In general, you appear to obsessed with re-landing after a failure. Were you taking a day off when Performance A was started? Have you not read the overviews of certification standards? It is intended that modern aircraft will be safe to operate from the start of their take-off roll until they are stationary after having commenced their takeoff roll. Basically Take-off Performance considers engine failures, wind, runways etc. and make an assumption that you'll either fly or stop. Flying and landing are NOT considered because it's too complicated and I'd also suggest beyond that capability of most people here, excepting yourself of course. If you want to do it that's fine. Fill your boots but don't try to sell it here.
If runway is long enough why not reland rather then continue with unknown perhaps catastrofic problem into the air ( like Concord crew), perhaps into IMC, icing and God knows what else.
Would you continue takeoff with unknown huge bang in the back into IMC/icing conditions
In general, you appear to obsessed with re-landing after a failure. Were you taking a day off when Performance A was started? Have you not read the overviews of certification standards? It is intended that modern aircraft will be safe to operate from the start of their take-off roll until they are stationary after having commenced their takeoff roll. Basically Take-off Performance considers engine failures, wind, runways etc. and make an assumption that you'll either fly or stop. Flying and landing are NOT considered because it's too complicated and I'd also suggest beyond that capability of most people here, excepting yourself of course. If you want to do it that's fine. Fill your boots but don't try to sell it here.
According to wikipedia the US Federal Aviation Administration defines:
but strangely also
In the case of the Citation on 12000 feet then
Definition 1 V1 would be VR
Definition 2 V1 could be as low as zero knots
Now I understand why there is so much discussion.
V1 means the maximum speed in the takeoff at which the pilot must take the first action (e.g., apply brakes, reduce thrust, deploy speed brakes) to stop the airplane within the accelerate-stop distance.
V1 also means the minimum speed in the takeoff, following a failure of the critical engine at VEF, at which the pilot can continue the takeoff and achieve the required height above the takeoff surface within the takeoff distance
Definition 1 V1 would be VR
Definition 2 V1 could be as low as zero knots
Now I understand why there is so much discussion.
Correct, mostly, on definition 1; not so much on definition 2. By definition, V1 cannot be less than V1mcg. That means it must be a two engine take-off to Vef, which cannot be less than Vmcg.
GF
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Dariuszw . . .
..."Assuming sufficient runway length why restrict and deny myself an option of aborting takeoff at speeds much higher then V1..."
