Setting service ceiling?

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Airspeed
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Setting service ceiling?

Post by Airspeed »

I have looked at SDK, .cfg and .air files, plus articles on the web, but can't find anything to tell me how to set the service ceiling for aircraft.
Any pointers would be appreciated.
Thanks.

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Chris Trott
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Re: Setting service ceiling?

Post by Chris Trott »

There's not a setting for it. You can make a comment about it in the description, but since Service Ceiling is an aerodynamic limitation, then you have to tweak the aircraft's lifting surface geometries and thrust until it ends up right.

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Re: Setting service ceiling?

Post by Bjoern »

The service ceiling depends on cabin pressurization properties and is a certification limit, not capability. With supplemental oxygen and at low weights, a plane can go as high till lift, gravity, drag and thrust (or the structural integrity) put an end to it.

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Re: Setting service ceiling?

Post by Chris Trott »

While listed as a limitation, it is not a "certification limit".

From the FAA Pilot's Handbook of Aeronautics (pg. G-27) -
Service ceiling. The maximum density altitude where the best rate-of-climb airspeed will produce a 100-feet-per-minute climb at maximum weight while in a clean configuration with maximum continuous power.
Any restrictions due to cabin pressurization or oxygen supply are Operating Restrictions, not a "ceiling".

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Airspeed
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Re: Setting service ceiling?

Post by Airspeed »

Thanks for the replies, Gents.
Quoted from a web search result:
From FAA pilot handbook: The service ceiling is the altitude at which the aircraft is unable to climb at a rate greater than 100 feet per minute (fpm).
Regardless of the precise terminology, if you set the default Cessna 172 at 50,000ft, you can't get it above 60 knots, neither can you maintain altitude.
Once you have lost some tens of thousands of feet, controls start working again.
Other models of similar aircraft have the engine stall at high altitude, apparently due to lack of oxygen, but I'm not sure about this.
If you take off in the default C172, and just keep climbing, you won't get into orbit; the air is too thin, and you'll hit a point which I would describe as its service ceiling. I'll come back with some numbers on this in an edit.
Somewhere, somebody has given the aircraft a limitation on altitude. I can't see where that is input.

EDIT: It took me about 40 minutes to coax the Cessna up to 10,000 ft.
At that altitude, I could just about get 70 knots, but attempts to gently climb were not very successful; airspeed dropped back and it wanted to stall. Controls were not fully effective. According to on-line info. I should have managed 13-15,000 ft. Too impatient tonight. :dunno:

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Chris Trott
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Re: Setting service ceiling?

Post by Chris Trott »

Again, there's no single setting for it. You have to change the dimensions of lifting surfaces, the power of the engine, the prop, etc, to make it work. It's not something you just change one number and suddenly the plane magically climbs higher - just like on the real plane.

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Re: Setting service ceiling?

Post by Airspeed »

OK, thanks, Chris. ;)

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Re: Setting service ceiling?

Post by dfarrow »

Mike , just read this ; and tired OAP brain kicked in slowly . Thinking was from 1972 theory exams ... some thing about when rate of climb drops to a certian limit ....
Thanks Chris for reminding me that it is 100fpm .... Group Rollason Condor often gets to that in a UK summer .
On Caledonian Tristars Dash -1 , -100s , when heavy , warm air . Once at FL250 , we'd set v/s 100 , full climb power and let the speed build to M.86-M.87 . Could never make the French boundary [ from LGW ] at cruise level [ FL330 ] anyway . So radio call at handover include '' Tristar , slow climb '' . We reckoned passengers wanted to get to destination rapidly and were not interested in how high they went .
Mind you they were 25+ years old , carrying 393 pax + kids , and a 1 tonne spares pack in the hold .
When we [ BEA ] first had them they were 320 pax to Paris and 300 back from Tel Aviv . Brilliant wing , engines short of puff .
Dash -200s would have been good for charter work , but no under floor galley . Thus 40-50 pax less than Dash -1, -100 . Charter work not needing under floor freight capacity .

rgds dave f.

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Re: Setting service ceiling?

Post by Airspeed »

Hi Dave! Haven't seen you for a bit!
I did know that in real life, the design and statistics determine the ceiling, but thought that there may be an over-riding line in the .cfg. I'm fairly sure that there's one for rate of descent which damages the u/c on landing.

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Re: Setting service ceiling?

Post by dfarrow »

Mike , been reading , but not much 'riting lately ..
Crash sw. on / off works for me ! 'Fraid I don't know what the civil certification limit is for vertical speed on landing , Must be in BCARs or JAR , EASA certification standards . [ does brain remember 6ft/second vertical speed ? ]
Think that Naval a/c are certified to 20ft/second [ for carrier landings , being no flare technique ] , or is that civil ...Maybe the Naval Aviators would know ?

rgds dave f .

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