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Jul 11, 2019, 01:55 PM
flyin' fool
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Discussion

A Delta Aerodynamics Abbreviated Disortation ............


Check what Pat says in his comment under 'A Little About Deltas' here …………………… https://www.rcgroups.com/forums/show...erfly-E-Review
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Jul 12, 2019, 05:00 AM
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Buncha nonsense. Deltas stall just like any other wing. The reason they can be flown as described is because they tend to be very lightly loaded wings with high thrust-to-weight ratios and control surfaces that are placed directly in the prop wash. With those characteristics, it doesn't really matter when or where laminar flow separation occurs, just as long as you still have power to the prop.

I can see where there may be a small stability advantage over a wing with a straight leading edge if the delta's wingtip vortex occurs far behind the CG, but that's really just a convenient result of a generally inefficient shape, much like the "drag stabs" on a finless wing.
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Jul 12, 2019, 05:43 AM
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Umm..., yeah nonsense regarding this: "This brings two features to a delta wing’s flight characteristics. One, you can’t stall them..."

Just tell that to these guys (skip to 3:40):

Dassault Mirage III Stall Tests (Vrilles) (10 min 58 sec)


The thing about the vortices IS true, but that's a very small gain compared to the the awful inefficiency (drag) of flying at very high AOA.
Also, just about any super-low aspect ratio plane in our model world will exhibit ability to fly at very high AOA, not just delta shaped.
Jul 12, 2019, 05:48 AM
Registered User
Yes. a delta stalls but in rather a different manner to a conventional wing so the centre of pressure remains more or less in the same position. In addition the drag rises at a constant rate rather than suddenly increasing so provided you have sufficient thrust a delta can be kept 'flying' in a controlled manner at angles that would normally be considered a fully stalled state.

Did Concorde, B58 Hustler or the Vulcan have their control surfaces in the prop slip stream?Nevertheless they could and did fly at very high angles of attack.
Jul 12, 2019, 08:11 AM
gpw
gpw
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I’d gotten a Superfly a while back , and it seemed quite Heavy EPP ( relatively) and was certainly indestructible …Flying was Ok … JMHO , lighter would have been Better …
Yet Deltas do stall , the pointy ones stalling then dropping straight down till recovery ….

We found personally that the ROUND planes weren’t as stall touchy, although did to “pitch hunt/ tuck under “ with undercambered airfoils at high speeds …

And then pick a delta ( any delta ) , add a working canard up front , then it pretty much won’t stall at all .
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Jul 12, 2019, 02:02 PM
flyin' fool
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Quote:
Originally Posted by Quorneng
...............… the drag rises at a constant rate rather than suddenly increasing ……………
That's the feature that when manipulated allows you to fly a delta in such extreme ways, that and a low wing loading. It just feels stall proof when you don't have to think about what it take to fly one. It's the reason why they are fun, because you can do more crazy stuff with one then a plank or swept wing.

Well, maybe except for a Crack Wing.
Jul 16, 2019, 01:50 PM
flyin' fool
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It's hard to find fault with a delta after you see how it flies here .......................
pibros by Crazy Horst.. (7 min 39 sec)


Check the antics at the beginning and end of the video.


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