17 Apr 2024, 21:52 [ UTC - 5; DST ]
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Post subject: Re: Zunum Aero Posted: 06 Oct 2017, 09:39 |
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Joined: 01/28/14 Posts: 752 Post Likes: +461 Company: CCDE, Inc Location: Houston - KDWH
Aircraft: M-35
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Attachment: Magnetic Air Cars.JPG I am accepting investments via paypal and bitcoins ( thanks Mike )
Please login or Register for a free account via the link in the red bar above to download files.
_________________ CHUCK N60988 C150
I'm retired now - don't need a fast airplane anymore.
Last edited on 06 Oct 2017, 09:46, edited 1 time in total.
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Post subject: Re: Zunum Aero Posted: 06 Oct 2017, 09:42 |
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Joined: 12/03/14 Posts: 19252 Post Likes: +23622 Company: Ciholas, Inc Location: KEHR
Aircraft: C560V
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Username Protected wrote: I am accepting investments via paypal. What, no bitcoin? Mike C.
_________________ Email mikec (at) ciholas.com
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Post subject: Re: Zunum Aero Posted: 06 Oct 2017, 11:04 |
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Joined: 12/17/13 Posts: 6352 Post Likes: +5538 Location: Hollywood, Los Angeles, CA
Aircraft: Turbo Commander 680V
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Mike, the way you fly today, is to get to altitude by using 100% of your power, but then you reduce for max cruise to maybe 65%. As you know, any turbine is very inefficient below 100%. So in a hybrid scenario, it would make sense to have multiple APU's scaled so that you might need, let's say, 3 of them to provide takeoff power, but then at cruise you shut one down and have the remaining two both at 100% producing the power needed for cruise portion. That's where they're at the most efficient. That will end up saving a lot of fuel.
Turbine aircraft are not flown like that today. If we pull back, our SFC goes up considerably. And if we don't pull back, our drag stays unreasonably high. Only in a hybrid solution could you perfect the power needed for cruise (best drag), without every having to reduce the APU's power (best engine efficiency).
It's gonna happen. Now we're looking at the demise of combustion engines in our own lifetime and just 3 years ago nobody would have been considered sane if they suggested such a thing.
Digital cameras would never work on paper either because they couldn't match the resolution of film. They still can't to this day. Yet, here we are with nobody using film.
_________________ Problem is the intelligent people are full of doubt, while the stupid ones are full of confidence.
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Post subject: Re: Zunum Aero Posted: 06 Oct 2017, 11:12 |
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Joined: 05/31/13 Posts: 1235 Post Likes: +602 Company: Docking Drawer Location: KCCR
Aircraft: C425
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Quote: If we pull back, our SFC goes up considerably. And if we don't pull back, our drag goes up. Only in a hybrid solution could you perfect the power needed for cruise (best drag), without every having to reduce the APU's power (best engine efficiency). The problem with that theory is that no one wants to cruise at the best drag speed. Turbines only lose 10-15% efficiency when operated at less than max power so you could easily pull the power back, go slower, and still have a net increase in fuel economy (look at the best range power charts in your POH). But no one does that because people buy airplanes to go fast, period.
_________________ ATP, CFI-I, MEI http://www.dockingdrawer.com
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Post subject: Re: Zunum Aero Posted: 06 Oct 2017, 11:23 |
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Joined: 12/17/13 Posts: 6352 Post Likes: +5538 Location: Hollywood, Los Angeles, CA
Aircraft: Turbo Commander 680V
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Yes, but people also want to run the AC on the ground and cool the cabin without a GPU. Or be able to taxi out as nr 7 in line for takeoff, wait on your clearance on battery power alone (and not stress about fuel and noise). Maybe do a local commute flight on battery power alone. Airports will eventually accept only, for noise abatement, that you have a hybrid aircraft, etc, etc.
With an APU or hybrid system you can do and meet all that.
It's not always about what is most efficient or best, it's what's most convenient. The history of innovation is full of products that were not more efficient or better, just more convenient. It will happen.
_________________ Problem is the intelligent people are full of doubt, while the stupid ones are full of confidence.
Last edited on 06 Oct 2017, 11:30, edited 1 time in total.
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Post subject: Re: Zunum Aero Posted: 06 Oct 2017, 11:30 |
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Joined: 10/26/16 Posts: 496 Post Likes: +692
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Username Protected wrote: Mike, the way you fly today, is to get to altitude by using 100% of your power, but then you reduce for max cruise to maybe 65%. As you know, any turbine is very inefficient below 100%. So in a hybrid scenario, it would make sense to have multiple APU's scaled so that you might need, let's say, 3 of them to provide takeoff power, but then at cruise you shut one down and have the remaining two both at 100% producing the power needed for cruise portion. That's where they're at the most efficient. That will end up saving a lot of fuel.
Turbine aircraft are not flown like that today. If we pull back, our SFC goes up considerably. And if we don't pull back, our drag stays unreasonably high. Only in a hybrid solution could you perfect the power needed for cruise (best drag), without every having to reduce the APU's power (best engine efficiency).
It's gonna happen. Now we're looking at the demise of combustion engines in our own lifetime and just 3 years ago nobody would have been considered sane if they suggested such a thing.
Digital cameras would never work on paper either because they couldn't match the resolution of film. They still can't to this day. Yet, here we are with nobody using film. I'm fairly positive film resolution has been exceeded long time ago in 35mm format, not so much in the medium format. My little Sony RX1R seems to blow anything I've ever shot my with Leica out of the water, even when using fine grain film. On a serious note, I don't ever recall "reducing" turbines at cruise at altitude? What are you referring to? They are running balls to the wall, producing all they can produce with the available air.
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Post subject: Re: Zunum Aero Posted: 06 Oct 2017, 11:39 |
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Joined: 12/17/13 Posts: 6352 Post Likes: +5538 Location: Hollywood, Los Angeles, CA
Aircraft: Turbo Commander 680V
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Username Protected wrote: An electric version of a jet engine wouldn’t make noise? Not when it's sitting waiting for a clearance or as no 7 inline for takeoff.
_________________ Problem is the intelligent people are full of doubt, while the stupid ones are full of confidence.
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Post subject: Re: Zunum Aero Posted: 06 Oct 2017, 11:53 |
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Joined: 01/29/08 Posts: 26431 Post Likes: +13066 Location: Walterboro, SC. KRBW
Aircraft: PC12NG
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Username Protected wrote: Not when it's sitting waiting for a clearance or as no 7 inline for takeoff. I don't think that's where the noise complaints come from. I'm usually hooked to a GPU or on battery power waiting for a clearance.
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Post subject: Re: Zunum Aero Posted: 06 Oct 2017, 12:05 |
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Joined: 12/17/13 Posts: 6352 Post Likes: +5538 Location: Hollywood, Los Angeles, CA
Aircraft: Turbo Commander 680V
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Username Protected wrote: Not when it's sitting waiting for a clearance or as no 7 inline for takeoff. I don't think that's where the noise complaints come from.
Perhaps not. But I know that the electric prop planes, like the Pipistrel etc are considerably less noisy than the Rotax powered version with he same prop size, so it is probably safe to assume that a ducted electric fan will emit less noise than a combustion fanjet of the same size. But this is just pure speculation on my behalf.
_________________ Problem is the intelligent people are full of doubt, while the stupid ones are full of confidence.
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Post subject: Re: Zunum Aero Posted: 06 Oct 2017, 16:08 |
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Joined: 07/22/14 Posts: 118 Post Likes: +53 Company: Robust.ai Location: Portland, OR
Aircraft: Bonanza A36TN
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Username Protected wrote: Perhaps not. But I know that the electric prop planes, like the Pipistrel etc are considerably less noisy than the Rotax powered version with he same prop size, so it is probably safe to assume that a ducted electric fan will emit less noise than a combustion fanjet of the same size. But this is just pure speculation on my behalf.
Here is a nice video about "quiet flight" from over a year ago. It does seem a lot quieter to fly electric. Erik Lindbergh says "It's awesome to see this plane flying, right overhead, 500 feet above. We're right underneath it and you can barely hear it...what really struck me was that absence of noise." https://www.youtube.com/watch?v=FlwKTZk5S-8And this isn't even a ducted fan. That might be even quieter.
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Post subject: Re: Zunum Aero Posted: 06 Oct 2017, 16:24 |
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Joined: 07/19/10 Posts: 2728 Post Likes: +1167 Company: Keller Williams Realty Location: Madison, WI (91C)
Aircraft: 1967 Bonanza V35
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Username Protected wrote: An electric version of a jet engine wouldn’t make noise? Much less.
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Post subject: Re: Zunum Aero Posted: 06 Oct 2017, 16:31 |
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Joined: 01/29/08 Posts: 26431 Post Likes: +13066 Location: Walterboro, SC. KRBW
Aircraft: PC12NG
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Username Protected wrote: An electric version of a jet engine wouldn’t make noise? Much less. Well, we got that going for us then.
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