Absolute and service ceilings in hover - max takeoff power or max continuous power
Thread Starter
Joined: Dec 2010
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From: Georgia
Absolute and service ceilings in hover - max takeoff power or max continuous power
Hi guys,
I need to find the 'service ceiling in hover' and also the 'absolute ceiling in hover' of a few helicopters as part of a study. (Note both are in hover, out of ground effect, NOT in forward flight, even though the term service ceiling usually applies to ceiling in forward flight).
Now I know how to do all the math, but it mostly depends on power requirements, and my definitions of these terms are a little shaky so I'm not sure which engine power to use.
My question is whether the engine is running at max takeoff power or at max continuous power in these cases. I was going to assume absolute ceiling in hover applies to the case when the engine is running at max takeoff rating power whereas for service ceiling in hover you are running at max continuous power. Or am I completely wrong and max continuous power is the only one of importance for both absolute ceiling and service ceiling in hover?
[For the record I realize that service ceiling in hover means you need to have enough power for a R/C of 100 ft/min at this altitude. Whereas absolute ceiling is when your R/C goes to 0 ft/min (because you have no excess power left to climb). My question is only about which power - max takeoff or continuous one must use in these definitions]
Thank you for clarifying
Gary
I need to find the 'service ceiling in hover' and also the 'absolute ceiling in hover' of a few helicopters as part of a study. (Note both are in hover, out of ground effect, NOT in forward flight, even though the term service ceiling usually applies to ceiling in forward flight).
Now I know how to do all the math, but it mostly depends on power requirements, and my definitions of these terms are a little shaky so I'm not sure which engine power to use.
My question is whether the engine is running at max takeoff power or at max continuous power in these cases. I was going to assume absolute ceiling in hover applies to the case when the engine is running at max takeoff rating power whereas for service ceiling in hover you are running at max continuous power. Or am I completely wrong and max continuous power is the only one of importance for both absolute ceiling and service ceiling in hover?
[For the record I realize that service ceiling in hover means you need to have enough power for a R/C of 100 ft/min at this altitude. Whereas absolute ceiling is when your R/C goes to 0 ft/min (because you have no excess power left to climb). My question is only about which power - max takeoff or continuous one must use in these definitions]
Thank you for clarifying
Gary
Joined: Oct 1999
Aviation Qualifications: ATPL
Posts: 7,373
Likes: 931
From: Den Haag
It will be whatever the RFM graph says. AC-29 says the tests are done using Continuous power, but looking at a couple of RFMs I see some say TOP only and some have both TOP and MCP.
