Service Ceiling Calculation?

[SpaceCofee]

Hello friends

I have some initial informations about a piston helicopter such as weight, disc loading, rotor diameter, enginge hp, rotor rpm and etc. . but i don't know how calculate service ceiling of helicopter. :confused: do you help me?

[KenSandyEggo]

Welcome Susan,

Isn't that set by the manufacturer, or are you talking a home-built? If you built it, you can set it wherever you want. The practicality would be another matter. Calculating the ceiling may be able to be better answered by one of our mathematical gurus that hang around here. Maybe it's as simple as climbing until it doesn't climb anymore, and that's your ceiling. As you can see, the more I ramble on, the more you can see that I don't know much about what I'm saying. :p

[TomCarlisle]

I seem to remember, during my training days a long time ago, that service ceiling was defined as that altitude at which the aircraft will climb at 100 feet per minute.

[brett s]

You'll have to actually test fly it to get that value - I also seem to recall what Tom posted as being the definition.

[gyropilot]

Speaking of service ceiling...

Over the Labor Day weekend I'll be taking my Rotax 503 powered GyroBee down to a large dry lake bed in south central Oregon for some high desert flying with friends. The dry lake bed is at 4100' MSL, and just for fun, I plan to take off and climb as high as I possibly can... hopefully to at least 10,000' MSL... then shut the engine off and glide back to the dry lake bed.

The Bing carbs on my engine now have the optional HAC (High Altitude Compensating) system from Rotax which automatically correct the air/fuel mixture for temp and altitude changes. The last time I was at the dry lake bed I didn't have this system and had to change main jets a couple times each day due to the large temperature swings from the cool 50 degree mornings to the 95+ degree afternoons. On that trip I climbed to about 7,500' MSL and the engine was running very rich with corresponding cool EGT's. Under those conditions, the climb rate had deteriorated to 100 fpm by that altitude.

I'll report back how the altitude attempt went after the trip.

Regards,

John L.

[gyromike]

John,

Are the HAC kits still available?
Olenik Aviation used to have them, but their website was down last time I checked.

[gyropilot]

Are the HAC kits still available?Unfortunately no Mike.

I bought mine on eBay last year from a fixed wing UL owner who originally bought it from Olenik (Green Sky Adventures, Inc.) before they could no longer sell them. According to information I'd read on their web site at one time, the HAC chambers became scarce when Olenik started selling a lot of them again (at a reasonable cost compared to Rotax) and finally the supply dried up.

They now sell a manual mixture control system that works on the same basic principle as the automatic mixture control:

http://www.greenskyadventures.com/bing/HACmanorder.htm

Be sure and use the pull-down menu at the top center of the page to get to all kinds of interesting information.

The automatic HAC system I have works perfectly. No matter the altitude or OAT, the EGT stays nailed wherever it's adjusted at (by the jetting of the carbs). I assume the manual system would work just as well, except obviously the mixture would need to be manually tweaked from the cockpit for major changes in altitude and temp.

Best regards,

John L.

[SpaceCofee]

thank you frinds
I am aerospace aerodynamic engineer. for exercise, i wanted to do primary design of one piston helicopter. some parametrs are calculated. but i don't know, are service ceiling calculated before fly?

[brett s]

Like I said earlier in the thread, you have to get that from flight test...

You can make an educated guess from calculations when designing the machine, but all performance data in the end is derived from flight test.

[SpaceCofee]

thank you brett s for information.