Service Ceiling

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R-2800-59
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Joined: 23 Jun 2010, 15:45

Service Ceiling

Post by R-2800-59 »

Dear Community,

flying a lot in the Connie those days I wondered how high I can get without ruining my career.
On step climbs she seems to be easily capable of reaching FL270 or even more, although I never tried it.
I guess the limitation to 24,000ft might be more of a pressurization thingy, is it?

Any experience on what altitude the passengers start to feel dizzy?

Thanks in advance.

alan CXA651
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Re: Service Ceiling

Post by alan CXA651 »

Hi.
It depends on a few things as to max alt , if at max weight on takeoff , and step climbing you will be pushing it at 27000ft , also remember as you get higher , you get to what is called coffin corner , this is where your max speed and stall speed are very close together , and only modern autopilots can maintain level flight at these conditions , presurisation should not be a problem , but control of the aircraft will be a problem , its also a case of how powerfull the engines are before they run out of enough power to keep you there , i have had the connie at 27000 , and i did not like it , max alt i feel compatable with at max weight is 20000 , and if less than max weight and depending on length of flight , i might take her to 25000 max.
regards alan. 8)
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flapman
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Re: Service Ceiling

Post by flapman »

I would also consider FL250 as the max.

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Jacques
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Re: Service Ceiling

Post by Jacques »

Flapman has got it right: according to the manual the cabin alt at 20,000’ is 8,200’ and at 25,000 its 11,400 feet. So at 25,000 you might start to get people feeling not so good ( in real life). Of course there is no better guide than passenger response...so take it up and let the passengers guide your decisions as to what your max might be.

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R-2800-59
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Re: Service Ceiling

Post by R-2800-59 »

Thanks for the fast responses!

On longer trips (over 1200-1500nm) I always bring her up to 24k feet, from 20-21k (depending on gross weight) I let her climb gradually as fuel load decreases. I have no problems at all regarding control issues at that altitude and she performs exceptionally well, reaching 240kts+ ground speeds with a fuel burn of around 1600-1800 lbs/hr.
I know about the coffin corner issue as on my first flights I tried to let her climb all the way up on climb settings what led to a steep angle of attack due to low speeds. A lot of fuel gets wasted this way, especially on trying to accelerate again from this situation without descending a little.
I will try 26k for a soft start...

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CAPFlyer
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Re: Service Ceiling

Post by CAPFlyer »

I think you're missing point of the responses. If you're worried about your career, don't go above FL250. Above that, the cabin pressure will be way too low and will result in lower passenger ratings because of it. Don't push your altitude too much. In a piston airliner, the difference of 2,000 feet is pretty minimal to speed and overall fuel consumption. You step climb not because you can, but because the winds favor it. At propliner speeds, winds are going to be much more of a factor against your fuel consumption than engine efficiency. Plan your cruise altitudes between FL200 and FL240 when you can, FL250 if you must, but don't be against cruising at a lower altitude if the winds are favorable. I've made 8-10 hour legs all below FL200 because the winds above were 20+ knots against me. Had I gone higher, even full tanks wouldn't have gotten me to the destination.
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flapman
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Re: Service Ceiling

Post by flapman »

Jacques wrote: 20 Sep 2020, 02:16 Flapman has got it right:
Thanks,
Of course there is no better guide than passenger response
Sure there is! They're called supplemental oxygen regulations!
...so take it up and let the passengers guide your decisions as to what your max might be.
The regulating body decides what the maximum is, not the passengers (you could argue in representative government they've decided through the regulation). But that adds incredible complexity to flight simulation. You have to ask questions like:

What type of operation is this legally considered?
Who regulates this operation?
What is the date of my simulated flight?
What is the time of day (yes, apparently some authorities at some dates determine oxygen requirements based on day or night)?
How is my aircraft equipped (not just pressurization: how many oxygen bottles, what is their capacity, where are they located, how easy are they to use, when will crew and passengers use them)?

The easy answer is just to call it FL250 and be done with it 8)

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Jacques
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Re: Service Ceiling

Post by Jacques »

I think you’re over-thinking my comment 😂

Everything you write is true - but the passengers are still a great source of feedback!

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