OEI Service Ceiling vs Category A
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OEI Service Ceiling vs Category A
Hello, here is a Helicopter 101 question for you that worths 10 points =)
I just saw a graph for a halicopter, telling about the OEI service ceiling data, changing with MTOW, Altitude and temperature. (max. permissible altitude/temp/MTOW to achieve 100ft/min climb rate) (graph did not have an initial condition about Vtoss or Vy)
Knowing that the helicopter is capable of CAT-A operations, can i use this graph to show the CAT-A capabilities of the helicopter? (hint: 0-200 ft requires a min. of 100ft/min climb rate @ Vtoss)
Or am i completely mixing up two completely independent subjects, and looking for the answer to (1 apple + 1 egg = ?)
I just saw a graph for a halicopter, telling about the OEI service ceiling data, changing with MTOW, Altitude and temperature. (max. permissible altitude/temp/MTOW to achieve 100ft/min climb rate) (graph did not have an initial condition about Vtoss or Vy)
Knowing that the helicopter is capable of CAT-A operations, can i use this graph to show the CAT-A capabilities of the helicopter? (hint: 0-200 ft requires a min. of 100ft/min climb rate @ Vtoss)
Or am i completely mixing up two completely independent subjects, and looking for the answer to (1 apple + 1 egg = ?)
No - is the short answer!
100 ft/min to 200 ft (actually from 35 ft or 15 ft, depending on the profile used) is at either 2 minute or 2.5 minute power - depending on the ratings available - and Vtoss. From 200 ft to 1000 ft, the RoC required is 150 ft/min at OEI MCP (or 30 minute power) and Vy (Vbroc.) Your graph will almost certainly be Vy and MCP, so doesn't really apply to either of these segments.
Additionally, the RTOM may be limited by the first or the second segment, depending on the Vtoss/Vy relationship - typically low Vtoss will result in the limiting mass, whereas a Vtoss that tends towards Vy will result in the second segment being the limiting factor.
100 ft/min to 200 ft (actually from 35 ft or 15 ft, depending on the profile used) is at either 2 minute or 2.5 minute power - depending on the ratings available - and Vtoss. From 200 ft to 1000 ft, the RoC required is 150 ft/min at OEI MCP (or 30 minute power) and Vy (Vbroc.) Your graph will almost certainly be Vy and MCP, so doesn't really apply to either of these segments.
Additionally, the RTOM may be limited by the first or the second segment, depending on the Vtoss/Vy relationship - typically low Vtoss will result in the limiting mass, whereas a Vtoss that tends towards Vy will result in the second segment being the limiting factor.
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yeah that's what i thought but just trying to validate =)
I just found it kinda unnecessary for someone to put an OEI service ceiling graph to an introductory brochure about a helicopter, started thinking about it, and concluded to the most irrelevant question.
Thanks for the detailed answer, being an aerospace engineer, im kinda new to helicopters (never took a course about it) and still learning about the performance. And people in the forum answered every single one of the questions of mine with patience.
Thanks again =)
I just found it kinda unnecessary for someone to put an OEI service ceiling graph to an introductory brochure about a helicopter, started thinking about it, and concluded to the most irrelevant question.
Thanks for the detailed answer, being an aerospace engineer, im kinda new to helicopters (never took a course about it) and still learning about the performance. And people in the forum answered every single one of the questions of mine with patience.
Thanks again =)
OEI performance is important when flying under FAR Part 135. The aircraft has to have sufficient performance to maintain a safe altitude after sustaining an engine malfunction.
135.181 Performance requirements: Aircraft operated over-the-top or in IFR conditions.
(a) Except as provided in paragraphs (b) and (c) of this section, no person may—
(1) Operate a single-engine aircraft carrying passengers over-the-top; or
(2) Operate a multiengine aircraft carrying passengers over-the-top or in IFR conditions at a weight that will not allow it to climb, with the critical engine inoperative, at least 50 feet a minute when operating at the MEAs of the route to be flown or 5,000 feet MSL, whichever is higher.
135.181 Performance requirements: Aircraft operated over-the-top or in IFR conditions.
(a) Except as provided in paragraphs (b) and (c) of this section, no person may—
(1) Operate a single-engine aircraft carrying passengers over-the-top; or
(2) Operate a multiengine aircraft carrying passengers over-the-top or in IFR conditions at a weight that will not allow it to climb, with the critical engine inoperative, at least 50 feet a minute when operating at the MEAs of the route to be flown or 5,000 feet MSL, whichever is higher.
