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Just an idea...

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Samuel

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Hi all together

I recently saw some pictures of planes like Custer's channelwings, or the Edglely Optica... and after a few days there was something like an idea forming in my head. (by the way: i really hope that my school-taught-english allows me to really make what i imagine... If that's not the case -> please ask!)

WHAT IF you build up a plane somehow similar to the Optica with the engine and esp. the prop more or less 'between' the wings, and then deflected the whole thrust from that prop to the sides so it blows a nice wind over the upper surface of the wing.
Having something about Venturi and Bernoulli in the back of my mind: Shouldn't that generate lift? Or to dream on: Would it be possible to build a VTOL-plane just by deflecting the thrust of the propellor to bith sides during landing and takeoff?

I played around with some numbers..... but as I
1. am a pure autodidact (somhow unsure of what he's calculating sometimes)
2. have no real data or at least a guess of the different dimensions (e.g. the speed of the air blown over the wing surface),
I didn't come to reliable results. (The results I got told me OK, BUT as I wrote earlier I'm quite far from being anything like firm with aerodynamic calculating):lick:

So...... .... any opinions?

greets
Samuel

ps: I'm working on some images of what i have in mind... they'll come later
 

Jay Kempf

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Generally blowing air sideways or perpendicular to flow gives you nothing but a loss of HP to drag. Directing prop thrust down can give VTOL but it is not easy and it takes a lot of HP. There is a good reason a helicopter turns a very large prop very slowly and with very little AOA.

Welcome. Your english is a lot better than my german :)
 
S

Samuel

Guest
Hi
Still the question pops up in my head: would it work?
fast air over the wing, slow air under the wing, fast air means low pressure and low pressure over a surface -> lift ?

Samuel
 

orion

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Span-wise flow would not only do nothing beneficial for you, it would actually kill any lift you would normally have by deflection the aft-ward flow you have due to forward motion.

As far as vertical lift due to deflected flow is concerned, the answer is simply "no". A conventional engine/prop does not deliver sufficient thrust to act in this manner in a conventional application. You would need a prop the size of helicopter blades to come anywhere near the efficiency you need to generate that much lift force but even then the flow would have to be direct - deflected flow looses a lot of energy in the turn so any form of VTOL in this manner is unlikely.
 

revkev6

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also note that some form of air was used at the tail to stabilize the plane during these high deflection flights. it was a very complicated and inefficient setup.
 
S

Samuel

Guest
@ orion
As you say it doesn't generate enough lift: Is there a way to calculate it? (Ok I mean: there surrely IS a way... but i don't know it)
All the time I had a saying of Willard R Custer in mind: It doesn't matter how fast the wing moves through the air. It matters how fast the air moves over the wing...
 

wsimpso1

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"Is there a way to calculate it?"

Yes. But if you have to ask, it is going to take considerable education then most likely CFD.

Billski
 

Aircar

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Samuel, -your idea is actually not so stupid. The concept of spanwise blowing is well known in the literature but usually only on relatively low aspect ratio aircraft since it needs the flow to be carried away by the tip vortex to be stable (look up tip blowing also -discharging air through the wing tip in a spanwise direction increases lift and reduces induced drag --that concept could be easier to arrange )

Lockheed tested a jet Caproni sailplane as a laminar flow testbed and arranged a spanwise jet blast to clear off any dust prior to doing wake rake testing --expecting a reduction in lift, but found the reverse --it turns out that the combination of chordwise airflow and spanwise jet combine to form a horizontal vortex that increases the effective camber and lift. --to get the best effect the wing needs sweep so that the vortex doesn't just blow off the wing . See the Kasperwing thread for one aircraft that exploits this form of lift (without a powered air jet although this was tested in a wind tunnel by SAAB as part of an evaluation of the Kasperwing and the vortex shields and special flaps )

The Bell-Bartoe experimental aircraft used the exhaust from a turbine engine discharged over the wing and assisted by a fixed van to entrain more ambient air -it acheived a phenomenal speed range (all these things should be on the web ) Another aircraft using this sort of concept is the roadable Strongmobile by Richard Strong --he has a comprehensive website and shows the discharge idea.

The Australian agents for the Optica were based close to my old workshop on the same airport --it was way too expensive and a very complex structure but very quiet in operation --their demonstrator is still here somewhere as far as I know. (the Custer wing and the Vought XF5 also referred to are both using slipstream immersion to get low flight speeds but strictly chordwise flow )

BTW where in Germany are you ? I used to live in Schwabenland -- Kirchheim u Teck actually .
 
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