19 Apr 2024, 00:11 [ UTC - 5; DST ]
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Post subject: Re: Otto Aviation Celera 500L Flew This Week Posted: 17 Feb 2021, 13:23 |
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Joined: 08/26/15 Posts: 9542 Post Likes: +8779 Company: airlines (*CRJ,A320) Location: Florida panhandle
Aircraft: Travel Air,T-6B,etc*
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Username Protected wrote: the flying magazine article is available on line now https://www.flyingmag.com/story/aircraf ... 0l-design/interesting thoughts I wonder if they're using the fuel return for some of the heat rejection at 65,000 feet. The thought hadn't crossed my mind until just now. It's how gas turbines cool their oil at altitude- a fuel-oil heat exchanger heats the fuel and cools the oil (good because it puts both fluids at a better working temperature), most of that fuel flow gets returned to the tanks or used in motive flow pumps). Oil cooling for that diesel may not be as demanding as a typical turboprop or jet, maybe there's some capacity in the Celera's recirculated fuel that can substitute for some cooling system capacity. Or maybe that's a terrible idea... I'm not sure where to start on the napkin math.
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Post subject: Re: Otto Aviation Celera 500L Flew This Week Posted: 19 Feb 2021, 16:25 |
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Joined: 10/18/11 Posts: 1031 Post Likes: +587
Aircraft: Seabee Aerostar 700
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what altitude have they flown it at?
there is a huge shortage of information that isn't advertising copy
another vaporware aircraft like the eclipse?
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Post subject: Re: Otto Aviation Celera 500L Flew This Week Posted: 19 Feb 2021, 16:47 |
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Joined: 02/28/17 Posts: 1213 Post Likes: +1191 Location: Panama City, FL
Aircraft: Velocity XL-RG
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Username Protected wrote: what altitude have they flown it at?
there is a huge shortage of information that isn't advertising copy
another vaporware aircraft like the eclipse? I don't know if I would consider an aircraft that's flown as vaporware. And Eclipse actually sold airplanes so that's definitely not vapor.
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Post subject: Re: Otto Aviation Celera 500L Flew This Week Posted: 19 Feb 2021, 18:19 |
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Joined: 11/15/17 Posts: 685 Post Likes: +350 Company: Cessna (retired)
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Username Protected wrote: the flying magazine article is available on line now https://www.flyingmag.com/story/aircraf ... 0l-design/interesting thoughts I wonder if they're using the fuel return for some of the heat rejection at 65,000 feet. The thought hadn't crossed my mind until just now. It's how gas turbines cool their oil at altitude- a fuel-oil heat exchanger heats the fuel and cools the oil (good because it puts both fluids at a better working temperature), most of that fuel flow gets returned to the tanks or used in motive flow pumps). Oil cooling for that diesel may not be as demanding as a typical turboprop or jet, maybe there's some capacity in the Celera's recirculated fuel that can substitute for some cooling system capacity. Or maybe that's a terrible idea... I'm not sure where to start on the napkin math.
Most gas turbines I am familiar with do not return fuel to the tank unless they use motive flow jet pumps. Doing so can cause several problems:
Back when Jp-4/Jet B was routinely approved, the hot fuel could cause problems with jet pump cavitation.
Nowadays, for Part 25 airplanes, return of hot fuel through the jet pumps can cause problems with 25.981 fuel flammability compliance.
Many gas turbine engines specify a maximum engine inlet fuel temperature that does not allow for the combination of max tank fuel temperature increased by hot motive flow through jet pumps.
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Post subject: Re: Otto Aviation Celera 500L Flew This Week Posted: 19 Feb 2021, 23:54 |
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Joined: 11/22/12 Posts: 2595 Post Likes: +2352 Company: Retired Location: Lynnwood, WA (KPAE)
Aircraft: 1993 Bonanza A36TN
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Username Protected wrote: Most gas turbines I am familiar with do not return fuel to the tank The PT6 does, I believe it always has. For the latest version, the PT6E-67XP in the PC-12, they increased the flow of warm fuel back to the tanks enough to no longer need Prist.
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Post subject: Re: Otto Aviation Celera 500L Flew This Week Posted: 20 Feb 2021, 14:53 |
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Joined: 10/18/11 Posts: 1031 Post Likes: +587
Aircraft: Seabee Aerostar 700
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Username Protected wrote: what altitude have they flown it at?
there is a huge shortage of information that isn't advertising copy
another vaporware aircraft like the eclipse? I don't know if I would consider an aircraft that's flown as vaporware. And Eclipse actually sold airplanes so that's definitely not vapor.
there is a long ways from something you get in the air and one that meets the original goals and advertising and is saleable.
just look at the Eclipse specs when it was first built and flown and what they finally were able to build and sell. and they had investments of something like $1 billion to do it The first one they flew to get the deposits had cruise missile engines with a lifetime of 25 hours. The eclipse was originally priced at $750,000, gross weight of 4000 lbs when it finally flew for customers it weighed 6000 lbs and to make money they priced it at something like $2.15 million
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Post subject: Re: Otto Aviation Celera 500L Flew This Week Posted: 20 Feb 2021, 15:50 |
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Joined: 11/15/17 Posts: 685 Post Likes: +350 Company: Cessna (retired)
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Username Protected wrote: Most gas turbines I am familiar with do not return fuel to the tank The PT6 does, I believe it always has. For the latest version, the PT6E-67XP in the PC-12, they increased the flow of warm fuel back to the tanks enough to no longer need Prist.
You are right. This is mainly to prevent an airlock of the main engine pump. I am most familiar with aircraft with motive flow, which performs this function, and forgot about the return for aircraft without. I am a little unclear about whether the return is continuous or just when needed, such as starting.
Interesting that the latest Pilatus gets enough heat from this to not need Prist.
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Post subject: Re: Otto Aviation Celera 500L Flew This Week Posted: 21 Feb 2021, 13:45 |
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Joined: 02/28/17 Posts: 1213 Post Likes: +1191 Location: Panama City, FL
Aircraft: Velocity XL-RG
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Username Protected wrote: I don't know if I would consider an aircraft that's flown as vaporware. And Eclipse actually sold airplanes so that's definitely not vapor. there is a long ways from something you get in the air and one that meets the original goals and advertising and is saleable. just look at the Eclipse specs when it was first built and flown and what they finally were able to build and sell. and they had investments of something like $1 billion to do it The first one they flew to get the deposits had cruise missile engines with a lifetime of 25 hours. The eclipse was originally priced at $750,000, gross weight of 4000 lbs when it finally flew for customers it weighed 6000 lbs and to make money they priced it at something like $2.15 million
I suppose it's in the eye of the beholder.
For me, "vaporware" is something that is exactly that: Vapor. As in non-existent. In the case of airplanes it would be one that was either never built or built but never flew. If you want to start adding in whether it met performance specs and price, then I think just about every airplane flying is vaporware. Especially military aircraft. I can't think of the last one of those that hit the projected cost.
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Post subject: Re: Otto Aviation Celera 500L Flew This Week Posted: 09 Oct 2021, 11:28 |
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Joined: 04/26/13 Posts: 19903 Post Likes: +19620 Location: Columbus , IN (KBAK)
Aircraft: 1968 Baron D55
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Username Protected wrote: One good reason that fuselages aren't designed with extensive laminar flow is the conflict of forward visibility & windshield design with a laminar shape. The requirements precisely conflict. Look at the picture below and note the position of the pilot and the forward visibility or lack thereof. Creating any reasonable amount of forward visibility is going to be severely challenging. More challenging that that is having any chance for reasonable optics through a windshield that's canted at that severe angle. Yes, but it’s the 21st century, do we really need direct visual observation to fly the plane? (Spoiler alert: No, we don’t) As a pilot I’d like some nice windows to look out of, but for the forward view I’d be just fine with an image from a camera overlaid with a HUD. If the display goes tango uniform I can make like Lindbergh and slip it to short final and land.
_________________ My last name rhymes with 'geese'.
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