08 Jul 2025, 15:01 [ UTC - 5; DST ]
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Post subject: Re: Citation 650 to FL500  Posted: 18 Jun 2025, 13:24 |
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Joined: 08/24/13
Posts: 9860
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Company: Aviation Tools / CCX
Location: KSMQ New Jersey
Aircraft: TBM700C2
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Username Protected wrote: Anyone else on here have experience selling 20 series Lears? Was it common to take them up to 430 or 450 to see if the engines had issues? It’s been a long time, but I don’t recall any 20 series that were certified above 410. Why would someone take the plane above it’s certified ceiling to prove the engines can operate there? Might as well test it’s orbital reentry capability just because. 
Lear 24 below s/n 140 were FL410, after that FL450
Lear 25 was FL450, D/F models with the right mods were FL510
But I never heard of the "test" as Chip describes.
There were acceleration tests to be done at altitude. Maybe some of those would cause a compressor stall, I don't recall hearing about anything like that.
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Post subject: Re: Citation 650 to FL500 Posted: 18 Jun 2025, 13:28 |
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Joined: 11/01/08
Posts: 2690
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Username Protected wrote: Anyone else on here have experience selling 20 series Lears? Was it common to take them up to 430 or 450 to see if the engines had issues? It’s been a long time, but I don’t recall any 20 series that were certified above 410. Why would someone take the plane above it’s certified ceiling to prove the engines can operate there? Might as well test it’s orbital reentry capability just because.
24/25 - 45,000
28/29 - 51,000
http://airplanedriver.net/study/lr20.htm
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Post subject: Re: Citation 650 to FL500 Posted: 01 Jul 2025, 01:12 |
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Joined: 11/15/17
Posts: 1132
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Company: Cessna (retired)
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Username Protected wrote:
Did you start at max weight? Was it ISA?
Mike C.
It was years ago, so I have no idea as to ISA, but we would have been really close to gross weight in the examples. Again, those charts make no sense because the X (I flew SN 127) only held 13000 # of fuel topped.
I see the charts, they don't agree with my real world experience at all but I can't fully explain the why . Part of it can be explained away by the lower left of the chart - the wind effect portion but not enough for the difference I saw actually operating the airplane. They do look about right for what I saw through 430 or 430, but from there they make no sense. If you are at 430 @ ISA in 22 minutes, and the chart says you are sill climbing at 288 FPM, but then it says going from 430 to 450 take another 54 (81 - 27) minutes via a step climb, something doesn't add up. I will see if I can find my old books and see if I can find the difference. Brad
13,000 # of fuel is for nominal density JET A fuel at SLS temperature. It can be higher, especially with cold fuel.
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Post subject: Re: Citation 650 to FL500 Posted: 06 Jul 2025, 20:56 |
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Joined: 07/13/19
Posts: 596
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Company: USAF and Polaris Program
Location: FL
Aircraft: F-35A A-JET L39 A36
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It’s been a long time since I’ve flown a 650, but if I recall correctly, you had to remove the interior to get to 510 on a standard day. We made it close a few times with the interior in, but never to 510. The 650 actually has some impressive performance in the book.
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Post subject: Re: Citation 650 to FL500 Posted: 06 Jul 2025, 23:24 |
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Joined: 10/23/11
Posts: 265
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Location: KUZA
Aircraft: D95A
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I went to FL510 in a 650 once in the 3500 hours and 8 years on the airplane…sort of a waste of time and sorta scary. Couldn’t wait to start down. In cruise maybe ten minutes
very light on fuel and ISA -10. I wish I had a camera with me. Cellphones weren’t an
option back then. How time flies !
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Post subject: Re: Citation 650 to FL500 Posted: 06 Jul 2025, 23:34 |
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Joined: 12/03/14
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Company: Ciholas, Inc
Location: KEHR
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Username Protected wrote: I went to FL510 in a 650 once in the 3500 hours and 8 years on the airplane… At FL510, 89% of the atmosphere is below you. You are 89% the way to space in terms of air density. Mike C.
_________________
Email mikec (at) ciholas.com
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Post subject: Re: Citation 650 to FL500 Posted: Yesterday, 23:43 |
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Joined: 11/15/17
Posts: 1132
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Company: Cessna (retired)
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Username Protected wrote: I went to FL510 in a 650 once in the 3500 hours and 8 years on the airplane… At FL510, 89% of the atmosphere is below you. You are 89% the way to space in terms of air density. Mike C.
The final 11% is sort of tough, though.
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