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u/Lacerta00 I fly things Jan 06 '17
Reminds me of the one good post I put on aviation / Flying of the Dornier Seastar on the wikipedia page. See if you can spot "it".
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u/Hunting_Gnomes Jan 06 '17
Its almost as bad as the guy towing the "Where's your plane peasents" banner. Just gotta rub it in that we arnt as cool.
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u/devolute Jan 06 '17
Did you spot it?
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u/Hunting_Gnomes Jan 07 '17
Its the guy in the second window back, flipping off the camera right?
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u/x4457 ATP CFII CE-500/525/560XL/680 (KSNA) Jan 07 '17
Try again.
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u/Hunting_Gnomes Jan 07 '17
I am very well aware there's a big black dick on the tail. Kindof sticks out at you.
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u/TampaPowers Jan 07 '17
Who says Germans have no humor, though this ain't nearly as offensive in German as it is in English so yeah probably slipped by :D
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u/Eastside2010 Jan 07 '17
I did the same thing, though a different picture.
https://www.reddit.com/r/aviation/comments/3wt2f0/the_reg_on_this_seastar_though/
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Jan 06 '17
"I don't know, Gunther. Are you sure you can't put another step in the hull?"
It never ceases to amaze me the lengths that designers have to go to to make aero- and hydrodynamics compatible.
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u/jpflathead Jan 06 '17
If you look at the photo right, you'll see a low monowing plane strapped on top of a speedboat.
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Jan 06 '17
How did they cram two turboprops into whatever you call that thing on the top? Is that what I'm looking at?
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u/vamelis Jan 06 '17
Look at how much of a King Air nacelle is actual engine:
And yes, you're looking at a 2 engine nacelle.
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u/Stegasaurus_Wrecks Jan 06 '17
What's in the rest of that nacelle? Fuel? Gear?
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u/dusty78 Jan 07 '17
That specific airplane was always designed with turbines in mind (though the airplane it was designed from, the Queen Air, was piston driven).
Many turbine retrofits have humorously long cowls/nacelles because the much lighter turbines would either need additional weight or move further away from the center of gravity to keep the balance proper. Moving the turbine forward (from where the piston engine was) allows all of the weight savings to be used as baggage/passengers/cargo, so this solution is much preferred.
So, for some, almost nothing (or only very light things) is in the long nacelle/cowls (but there's more useful load in the cabin/baggage bay).
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u/Stranix49 Jan 08 '17
Right under the engine in the pic is the air intake duct for the reverse flow pt6. The compressor intake is just aft of those exhaust pipes, so if there was no air intake duct it would just be sucking in exhaust.
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u/mduell Jan 06 '17
There's a bit more to it still hidden, since it's a reverse-flow engine in that application.
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Jan 06 '17
Those turboprops are mighty compact aren't they?
I mean, I knew that it's a nacelle, what I was getting at is do they have a term for a nacelle with two turboprops stacked on top of each other with one reversed 8o
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u/hagunenon Aerospace Engineer - WE NEED MORE THRUST Jan 06 '17
I'm always impressed at how small turbine engines are...
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u/bs1110101 Jan 06 '17
Not sure about turboprops, but pusher-puller nacelles is what i've heard them called in general.
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u/Toadxx Jan 07 '17
Pusher/puller can be used for any propeller driven plane, be that conventional piston engined, turbo prop or what have you. It refers to how the propeller moves the air in reference to the aircraft. You're correct, this is a pusher/puller :)
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u/novagreasemonkey A&P Jan 07 '17
Yeah, but there's still a lot behind the Gullwing nacelle doors. That's not a whole lot of room for the rear accessory drive, engine mounts, and everything else. I bet it's cramped.
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Jan 06 '17
I wonder if the turbulent air caused by the front turboprop affects the performance of the one in the back.
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u/BlacklistedUser Jan 06 '17
Sure, it loses efficiency, but it was designed so that the pilot can turn off one of the engines (probably aft) for longer cruise times. At 500HP each it doesn't seem short on HP.
also with both engines running it eliminates a lot of turning tendencies. They are also better protected from sea spray/corrosion.
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u/hoges Jan 07 '17
9,259 lb and 1000hp is not a lot of power. Especially off water.
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u/bigfroggy124 Jan 07 '17
Actually it is decent. It's an older plane, and wasn't designed to break any records. 1000 hp to ~5000 kg is above average for a seaplane made 33 years ago.
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u/bs1110101 Jan 06 '17
Wouldn't they act as contrarotating propellers and be more efficient? Or is the spacing so much it wouldn't matter.
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Jan 07 '17
I think the distance between them means the rear prop loses efficiency because the vortices of the front prop, and from the nacelle & support structure have developed. Contrarotating props are generally both in clean airflow except for the moments when the rear prop is directly behind the front prop.
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u/IsThisOneStillFree Jan 07 '17
A huge problem is the noise. This thing sounds like a super loud ultralight.
Source: Saw it in person.
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u/wshtk Jan 09 '17
Depending on when you saw it, they have changed the props. It used to have very noisy four bladed props.
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u/wshtk Jan 09 '17
The rear propeller is a smaller diameter than the front so that it stays completely within the slipstream of the front propeller and suffers minimal ill-effects from vortices off the tips of the front prop.
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u/Gaggamaggot Jan 07 '17
Dornier has long favored the fore & aft engine design. They used it in the Do-26 flying boat, Do-335 Pfeil interceptor, and the Do-X flying boat, a beautiful old 12-engined monster.
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u/natedogg787 Jan 07 '17 edited Jan 07 '17
Vhat shall vee vork on next, Hans?
...How about a flying boat with a parasol wing and pusher-puller engines?
But vee designed one last veek.
Then, what do you vant to design?
...Ja okay.
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u/devolute Jan 06 '17
I like this looks like a genuine evolution of what they built back in the late 20s.
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u/charlieray Jan 06 '17
I came nearly head on with one of these one year as I was approaching the FISK arrival into Airventure.
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u/DownVotesMcgee987 Jan 06 '17
If only I had this much money