Spoon and Delta Wings
A guide to funny-looking wings - plus why one of them is extinct...
Ever looked at this and thought, 'What the hell?'
Juicy. Image from @NaturalParadigm.
That, ladies and gentlemen, is a spoon wing. And I love them.
The arrowhead-looking wing below; that is a delta wing - and this one doesn't exist anymore in F1.
A wonderful sketch from none other than @Giorgio_Piola.
Before we get stuck into the details of them, here's a short intro:
Aerodynamicists are constantly trying to find the perfect balance between downforce, efficiency, drag and packaging - in this case meaning the best possible design that the regulations, space, their overarching design philosophy and other aero devices allow (remember that an F1 car is aerodynamically useless in bits; it's a finely tuned collection of pressure differentials and airflows).
Jochen Rindt's infamous Lotus-Ford 72C. Image via @PrixRetro.
In the 1970s, engineers realised there was more to downforce than simply plonking on inverted aerofoils to the rear of their cars. They found that by tweaking the elements that make up wings (thickness, chord length - the width of a wing when viewed from above, wingspan - the length of a wing when viewed from above, its height above the ground and so on), they could make them much more powerful.
And it was during this explosion of aerodynamic innovation that the delta wing was born.
Many of Gilles Villeneuve's Ferrari's featured delta wings. From @GrgoryR.
In technical terms, a delta wing is defined as a wing which has a longer chord at the centre than at its tips - it's essentially swept back. What this does is produce less downforce at the tips, but crucially less drag too. As air flows over a wing, vortices tend to form at the outboard edges (this is partly why endplates exist) and whilst they can sometimes be useful, here they cause lots of drag.
The longer the chord, the worse the vortex, so the delta wing soon became a good way of reducing drag without changing the angle of attack of a wing (the angle at which air will hit a wing).
Sometimes when it gets humid enough, you can visibly see the vortex cores spiralling off a rear wing. Beautiful. @MotorsportWeek.
Furthermore, delta wings are configured to have a larger thickness at the centre of the wingspan (where the chord is longest) than at the edges.
They're not used in modern Formula 1 as rule-wise delta wings aren't efficient; to create the swept back effect you have to use less area than the regulations allow, and this, for F1 engineers who love to maximise everything, is taboo. Additionally,
You can still see delta wings on fighter planes, though - in aerospace engineering, drag is the biggest enemy...
A Eurofighter Typhoon. Cool name, cool plane. Via Google Search.
Now onto the concept I love.
It was only much later on that aerodynamicists realised they could also change the camber of the wings, i.e. how much it curves when viewed from the front. This is a pretty dramatic change from the delta wings which have a constant depth and no camber, but it has a fairly similar pressure distribution as well as reducing induced drag by limiting downforce at the tip.
Red Bull love a good spoon wing. Credit to @theJudge13Twts
The change in camber causes some side force at the points of curvature, which means not all of the air is contributing to completely vertical downforce and so the design is less efficient than a delta wing. They are, though, more responsive to tuning in that fairly simple changes can have opposing effects, and so they are very popular at tracks such as Spa and Spielberg - which are fast but still require substantial downforce levels.
Moreover, they better allow more modern ways of adjusting drag and downforce to be introduced onto their structure; for example those dips you see at the trailing edge of the upper element of the rear wing or the double support pillar. These both would be less effective on a delta wing.
Notice the dips? And the double pillar support? This was a wonderfully convenient picture for me.
Spoon wings have similar thickness profiles to delta wings; they grow thinner as you reach the edges too. To fully understand the effects of thickness on wings, you'd have to read a bunch of studies but essentially for low angles of attack, a higher thickness to chord ratio gives less induced drag from leading edge vortices, a bigger lift coefficient peak (more downforce) as well as a smaller lift to drag ratio.
Lots of ratios, I know.
Doesn't this look fun and not at all confusing! But look, there's a delta wing... From https://www.researchgate.net/publication/331943474_Effect_of_thickness-to-chord_ratio_on_aerodynamics_of_non-slender_delta_wing#:~:text=The%20results%20indicate%20that%20the%20effect%20of%20thickness-to-chord,leading%20edge%20vortex%20to%20three-dimensional%20separated%20flow%20regime.
So the next time F1 heads to Spa (or indeed any time an RB16B is out on track), you'll be able to bore your friends by explaining to them why that weirdly-shaped rear wing has a similar pressure distribution to a wing that hasn't been used in 30 years.
Isn't that great?
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Comments (1)
Fantastic piece! Love the technical articles from you. And I never thought Haas would be used as an aero example😂