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Mango

don't be afraid of high vertical speeds! 1800fpm no!

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The problem in FS with high FPS in descent is most aircraft gain a lot of speed.While an AI aircraft will descend at 7000 FPM and slow down, very few user aircraft can avoid gaining speed at a very fast rate.

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>I think the biggest problem is there is still no true IAS>hold in FSX. Dial up the desired IAS and altitude, and the AP>pitches to maintain the desired IAS.>>How this has been ignored for so long is beyond me.Guess I don't really follow (yet). What do you mean... Doesn't the current AP/ATHR hold the IAS you want it to hold...? If I dial in some ALT and some IAS, engage the appropriate modes the AP will hold these values. Anything wrong with that, varying from reality? Just curious.Thanks,Etienne

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Right on.>I remember seeing video of an A340 at some airshow climbing>nearly vertically which made me marvel at the power of the>thing, but wouldn't the pax loose their lunch climbing at this>rate.>>Mike.Actually I believe the A340 is known for it's ridiculous climb rate after take-off, but then again I assume this is only true for a usual long-range fully loaded flight.Anyways, I can only agree with Peter regarding VS... Airlines will often just use FLCH modes and similar, resulting in 4000+ fpm rates easily with no one complaining. I assume the power is the only limiting factor.Still I do have a question to any real world airline guru who might read this. What would be typical *cruise* rates e. g. during a step climb, or what would be a typical rate of descend after having reached the TOD (initial descend from cruise)?Thanks a ton.Etienne

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Guest emkramer

True IAS hold is not an autothrottle. The AP will pitch the aircraft to hold the desired speed at whatever throttle setting you're giving it. So if you're climbing out, throttle at, say, 97%, to an altitude of , say, 10,000 feet, at a selected IAS of 250 KIAS, the AP will climb at whatever rate necessary to hold 250 KIAS. AFAIK, this is found on every passenger carrying jet aircraft.

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>The problem in FS with high FPS in descent is most aircraft>gain a lot of speed.>>While an AI aircraft will descend at 7000 FPM and slow down,>very few user aircraft can avoid gaining speed at a very fast>rate.>You are right, in FS, I found that when climbing and pitching to hold a desired air speed is easy but when it comes to decents I have to constantly use speed brakes and flaps to slow the plane down if going beyound 2,000 FPM. It barely holds 250.

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>Still I do have a question to any real world airline guru who>might read this. What would be typical *cruise* rates e. g.>during a step climb, or what would be a typical rate of>descend after having reached the TOD (initial descend from>cruise)?Climbs are difficult to generalise as they are dependant on weight, altitude and aircraft. I've only experience on the little Airbus' but once above FL300 climb rates can drop off markedly. I've seen as much as around 2000fpm and as low as about 300fpm, depending on weight. You put on climb power and see what you get. If you are up against an altitude restriction you could trade some speed for altitude but at those altitudes there's not much to play with and it's a very short term measure.Pulling open climb (or FLCH for you Boeing guys) to descend from TOD we usually get somewhere in the mid/high 2000s to low 3000fpm.As I said, only applies to little Airbus' but I can't imagine other aircraft being hugely different to this.Hope this helps,Ian

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>The problem in FS with high FPS in descent is most aircraft>gain a lot of speed.It's a problem in real life too. If we find ourselves high we often try and wind the speed up with the speedbrakes out to get the very high descent rates needed to get back on the profile. If your speed limit is low (250 kts or less) then you will really struggle to get much more than 1500 to 2000fpm, even with the speedbrakes. If you need to slow down as well, bad luck, choose one. I personally prefer to go down, then slow down.You can use flaps but only if you're below the maximum speed for them and in the Airbus the first flap selection (available from about 210kts) isn't very draggy. You really need to get Flap 2 out, 180kts Flap 2 Open descent buys you just over 1200fpm, should get you back on the glideslope if you are a *bit* high.When things get really bad you can drop the gear, that's a hugely effective speedbrake and it can be used at fairly high speeds (250kts Vlo in the little Airbus' - and 280 once they're out). The problem is that they generate a lot of cabin noise and once down can't really be taken up again without worrying everyone. I've seen guys drop the gear very early to rein in a hot and high approach, it works very nicely but we really shouldn't have been there in the first place.Hope this helps,Ian

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Guest PARADISE

I like to take the FS aircraft out for a long test flight, especially when it's a new model. You'd be surprised at what you can learn about how your virtual airplane will handle at different phases of flight. Since this IS a simulator you can easily vary the airplane's weight, change altitudes, conditions of flight,etc. It will help you gain a much better understanding of what the airplane (even these virtual ones) is capable of and what it is not. We try to do this in real life too, ( in a sim of course ), I like to see just exactly what the limits of my airplane are, so that if the need ever arises I will know what I can and cannot do. Become a virtual test pilot and see what you can do. Ever try rolling a B-707 at about 1000' AGL?,....It's been done in real life.John M

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Guest Adrian Wainer

QuoteAny modern pressurisation controller will be able to handle very large rates of climb and descent without any discomfort. Passengers don't really care what your fpm is, only that their beer is cold, their hosties attractive and they arrive on time.UnQuotePoint taken about the capabilities of modern pressurization systems, that said high rates of ascent and the possability of a catastrophic pressurization system failure seems at least in principle an uncomfortable combination, also any pressure vessel will have its total life span reduced by rapid pressurization / rapid de-pressurization. Also all other things being equal, an aircraft in a rapid descent / ascent mode may lose a margin of safety should it suffer a mechanical failure or experience severe weather condtions.Best and Warm RegardsAdrian Wainer

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Guest Adrian Wainer

QuoteActually I believe the A340 is known for it's ridiculous climb rate after take-off, but then again I assume this is only true for a usual long-range fully loaded flight.Unquotehttp://www.cfm56.com/index.php?level2=engi...&level4=historyThe CFM-56 A340s have a reputation for being underpowered, the Rolls Royce engined variant is supposed to be much more satisfactory.http://en.wikipedia.org/wiki/Rolls-Royce_TrentBest and Warm RegardsAdrian Wainer

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Quite a bit of groupthink...e.g. the blind leading the blind...in this thread.The idea that you just accept whatever climb rate that rated climb power might give you is...wrong. Especially for jets capable of flying long legs with heavy fuel loads that might happen to be flying a short, light one.A 6000 fpm climb in a transport category jet will produce a deck angle that is absolutely uncomfortable for passengers. It's also very difficult to control smoothly when a controller issues a late climb restriction close to your altitude...you can end up doing a very uncomfortable nose-over to meet the restriction. Unless you're taking off from Kathmandu and trying to get above the towering Himalayan cumulogranite clouds nearby, there's no reasonable excuse for operating like that.In real world flying in the G-V, I generally use V/S mode with a ~3000 fpm maximum climb rate when operating the G-V light, for example. The G-V is capable of a 12-hour flight with 41000 lbs of gas...but is also typically used for flights of just an hour or two with less than 10000 lbs of fuel, and left to fly to its performance limits, it'll climb like a Saturn rocket with full climb power at those weights.No experienced real pilot just lets the airplane go to its own limits regardless of the impact is has on the paying customers in back. In fact cargo operators even keep a lid on climb rates when light (which isn't often).Also, the A340 is indeed renowned for its performance, all right...as one of the true pigs of the sky. The thing can barely get out of its own way at typical heavyweight loads for overwater flying. Lightweight, sure it can climb fast, like any other jet designed for heavy loads, but the 340 is typically operated at considerably lower thrust-to-weight margins than most, if not all, other airliners in this category.RegardsBob ScottATP IMEL Gulfstream II-III-IV-VSantiago de Chile


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From what I hear, one of the planes that pilots really need to watch the v/s on is the 777's with the GE 90-115's strapped to them. You got to figure that the high thrust of these monsters are really designed to get this heavily ladened bird up to cruise altitudes so down below say 10k, she wants to climb like a rocket almost regardless of if she is full or lightly loaded.For those curious about the pig like climb of the A340. Talk to any ABQ center controller about the LH A340 flight out of PHX in the summer...God awful.


Eric 

 

 

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Guest Adrian Wainer

Another issue with the big twin jets is that these aircraft have essentially been replacements for four engined aircraft like the Douglas DC-8 and Boeing 707 and have been designed to give superior performance with one engine out than the previous aircraft could provide with one of their four engines out, with the result with both engines operating they can climb like a bat out of Hyll, if less than fully loaded in favourable weather.Best and Warm RegardsAdrian Wainer

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>arises I will know what I can and cannot do. Become a virtual>test pilot and see what you can do. Ever try rolling a B-707>at about 1000' AGL?,....It's been done in real life.>>John MYeah, and it almost caused William Boeing to have a heart attack right on the spot, on that day in 1954. I heard that the test pilot was not authorized to do that. The roll did impress the dignitaries however...The problem with being a virtual test pilot in FS, is that you really need to disable "Aircraft Stress Causes Damage". After all, I don't think you could roll a 707 in the sim without the stress damage restarting your flight, although perhaps HJG has modelled theirs so that you can. (?)RhettAMD 3700+ (@2310 mhz), eVGA 7800GT 256 (Guru3D 93.71), ASUS A8N-E, PC Power 510 SLI, 2 GB Corsair XMS 2.5-3-3-8 (1T), WD 250 gig 7200 rpm SATA2, CoolerMaster Praetorian case


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In principle you are correct, that's why we don't do it all the time.By the same account the continued heating and cooling of the metal structure of the aircraft increase the chance of mechanical failure and the wings falling off. That doesn't mean we don't ever fly, just that we have the airframes checked on a regular basis and mitigate the risk.Let's agree that aviation is risky and lots of different people spend lots of their time mitigating all the various risks involved. If you feel the risks are too great then it is incumbent on you to take the appropriate action ... don't fly.Hope this helps,Ian

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