23 Oct 2025, 15:10 [ UTC - 5; DST ]
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Post subject: Re: Raptor Aircraft 5 Seat Pressurized 3,600 NM Range Die  Posted: 14 Aug 2021, 10:25 |
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Joined: 12/03/14
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Username Protected wrote: Has anyone see a practical use of a duct on a plane that cruised below mach .5? An example of my ducted fan: Attachment: jt15d-4.jpg Powered by a turboshaft engine of about 1500 HP. It does go mach 0.75, though, so it does cruise over mach 0.50. Mike C.
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Post subject: Re: Raptor Aircraft 5 Seat Pressurized 3,600 NM Range Die Posted: 14 Aug 2021, 13:00 |
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Joined: 01/06/08
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A good question - is a ducted fan quieter than a carefully designed large prop of the same low speed efficiency? Username Protected wrote: In that example and also the electric VTOL designs, the duct was chosen primarily for environmental noise concerns, not efficiency. The question was “practical use below Mach .5.” For low and slow operations near people, low noise is a very practical concern that must be considered in the design. If the question had been “use in a fast traveling machine like Peter is trying to build” then maybe not.
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Post subject: Re: Raptor Aircraft 5 Seat Pressurized 3,600 NM Range Die Posted: 14 Aug 2021, 13:02 |
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Joined: 01/06/08
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Yes, inlets are necessary to decelerate the inlet air to a speed the engine can handle. For supersonic flight the inlets can be extremely complex due to the need to decelerate high mach air to mach .3 or so, without loosing much energy. Username Protected wrote: Has anyone see a practical use of a duct on a plane that cruised below mach .5? An example of my ducted fan: Attachment: jt15d-4.jpg Powered by a turboshaft engine of about 1500 HP. It does go mach 0.75, though, so it does cruise over mach 0.50. Mike C.
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Post subject: Re: Raptor Aircraft 5 Seat Pressurized 3,600 NM Range Die Posted: 14 Aug 2021, 13:20 |
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Joined: 01/30/09
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Username Protected wrote: Powered by a turboshaft engine of about 1500 HP.
It does go mach 0.75, though, so it does cruise over mach 0.50.
Mike C. So will Raptor G2+ as soon as Peter adds mach 0.50+ cruise to the feature list. Probably take two Audi diesels with the crankshafts bolted together, but that's easy right?
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Post subject: Re: Raptor Aircraft 5 Seat Pressurized 3,600 NM Range Die Posted: 14 Aug 2021, 15:32 |
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Joined: 08/26/15
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Username Protected wrote: ...
An example of my ducted fan:
[nice pic of a 15D]
Powered by a turboshaft engine of about 1500 HP. Reinforcing your point, I think the horsepower going into just the fan is probably closer to double that- on takeoff I mean. Plus you've got two of those engines. Raptor is one 300hp engine (maybe 400?) though it's lighter at about a quarter the weight of your ride, which is to to say the math is not in Raptor's favor...
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Post subject: Re: Raptor Aircraft 5 Seat Pressurized 3,600 NM Range Die Posted: 14 Aug 2021, 15:50 |
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Username Protected wrote: Given the thrust limitations, will Raptor Mk II ever leave ground effect? (Watch it all the way through, there's an amphib at the end...) [youtube]https://youtu.be/Wv0qg7zrjl4[/youtube]
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Post subject: Re: Raptor Aircraft 5 Seat Pressurized 3,600 NM Range Die Posted: 14 Aug 2021, 22:03 |
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Can't help but be reminded of the good ol' Stipa Caprioni.  Attachment: stipa.gif Attachment: stipa2.gif
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Post subject: Re: Raptor Aircraft 5 Seat Pressurized 3,600 NM Range Die Posted: 14 Aug 2021, 22:14 |
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Joined: 04/26/13
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Username Protected wrote: Has anyone see a practical use of a duct on a plane that cruised below mach .5? An example of my ducted fan: Powered by a turboshaft engine of about 1500 HP. It does go mach 0.75, though, so it does cruise over mach 0.50.
If you recall the performance spec. for the original Raptor it would cruise at 350 knots. Certainly Raptor NG can do the same, which means that it will cruise at about Mach .53
I’ll leave it to all of you to decide which parts of that should be in green.
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Post subject: Re: Raptor Aircraft 5 Seat Pressurized 3,600 NM Range Die Posted: 14 Aug 2021, 22:29 |
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Username Protected wrote: If you recall the performance spec. for the original Raptor it would cruise at 350 knots.* Certainly Raptor NG can do the same, which means that it will cruise at about Mach .53
I’ll leave it to all of you to decide which parts of that should be in green. * ISA -100°
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Post subject: Re: Raptor Aircraft 5 Seat Pressurized 3,600 NM Range Die Posted: 15 Aug 2021, 07:16 |
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Username Protected wrote: Can't help but be reminded of the good ol' Stipa Caprioni. Attachment: stipa.gif Attachment: stipa2.gif I'll raise you by one ramjet [youtube]https://youtu.be/_F_JUlCbDFg[/youtube]
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Post subject: Re: Raptor Aircraft 5 Seat Pressurized 3,600 NM Range Die Posted: 15 Aug 2021, 07:37 |
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Joined: 01/18/11
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Username Protected wrote: Airplane is a pretty loose definition in the experimental world.
It flew. Having built an experimental aircraft, with inspections by an EAA Tech Counselor/DAR at every major phase of construction, documenting the build carefully (reviewed by DAR), and undergoing an airworthiness inspection I can assure you this is not the case for most experimental aircraft builds. I drilled out rivets (many hundreds) and re-made or replaced parts that would have been acceptable in production (repaired) - I even re-built some entire assemblies for relatively minor imperfections (one elevator I re-built because I wasn't happy with a mounting ring for an inspection plate - purely a cosmetic issue - on the bottom of the elevator where I was pretty much the only one who'd notice). I was not referring to build quality but to design. Most homebuilts are experimental in name only. Of course there are exceptions, but most in the experimental world are very serious about the pursuit. The "bad" actors tend to get culled from the herd in one fashion or another.
I was not referring to build quality but to design. Most homebuilts are experimental in name only.
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Post subject: Re: Raptor Aircraft 5 Seat Pressurized 3,600 NM Range Die Posted: 15 Aug 2021, 09:56 |
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Joined: 01/31/12
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Username Protected wrote: Can't help but be reminded of the good ol' Stipa Caprioni. Attachment: stipa.gif Attachment: stipa2.gif I'll raise you by one ramjet [youtube]https://youtu.be/_F_JUlCbDFg[/youtube]
Wait a minute!
Just to be clear, Monsieur Leduc was an absolutely brilliant engineer whose work helped push knowledge for both the French and the US air force.
Definitely in a class of his own.
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Post subject: Re: Raptor Aircraft 5 Seat Pressurized 3,600 NM Range Die Posted: 15 Aug 2021, 13:05 |
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Username Protected wrote: ...
An example of my ducted fan:
[nice pic of a 15D]
Powered by a turboshaft engine of about 1500 HP. Reinforcing your point, I think the horsepower going into just the fan is probably closer to double that- on takeoff I mean. Plus you've got two of those engines. Raptor is one 300hp engine (maybe 400?) though it's lighter at about a quarter the weight of your ride, which is to to say the math is not in Raptor's favor...
I think Peter is well into the "we don't need no stinking math" development method.
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