.
I have the Nye drawing... all this other stuff is just talk.
7 minutes of angle seems too small to be measureable, or even a design requirement, considering the time period., or it's an attribute for the particular plane measured.
There's certainly no aerdynamic reason for such an infinitesimal deviation.

No

No, it's not just talk. My data is from a 1943 workshop manual for the Spitfire Mk. V that I happen to own. I have no idea why Supermarine bothered to indicate such a small angle, but some draughtsman thought it was important enough to produce a drawing illustrating this.

As far as I know the wing twist (2.5° or 2°30') stated for the Spitfire wing does not include the wing tips. Depending on the intended application three types of wing tips were used, normal, clipped and extended.

/Red B.

A couple of points. A wing stalls when the angle of airflow (attack) exceeds 16 degrees or so. This is speed independent. That is, it can happen at any speed. (I honestly don't know why 'drag' is brought in as a factor by some in this discussion.)
Secondly, the drag of an airplane is comprised of 1) Form drag (parasite) 2) Skin friction and 3) Induced drag.
It is important to remember that at high speed, the first two predominate, while at low speed, induced drag forms the greatest component. Induced drag, is "induced" at low speeds, because the air starts to spill over at the wing tips, from the high pressure below, into the lower above. Because of the aircrafts forward motion, this turns into wing tip vortexes. The vortexes create the drag with the energy they absorb.
Obviously "spill-over" is worse at higher weights, because of higher pressure differences. I fly "Old Timer" RC, and for duration, we fly not at the best lift-drag ratio, but at the least sink speed. This is close to the stall, and, you guessed it, in the high induced drag range. One way to reduce tip vortexes, is wash out, because it reduces the pressure difference that is the cause of the drag vortexes. And yes, the reduced angle of attack of the wing tips, also means they will not be the first to stall; a much safer way to go.

I had the "pleasure" of maidening a "Red Hawk" today.
3-channel rudder-vator basic airplane. Servos pull the surfaces up against rubber bands which pull them down.
The basic plane was 1 oz tail heavy.
The wing was mounted so the leading edge was above the leading edge forward stop on the fuselage, giving it some extra incidence.
The rubber bands pull it forward over the stop.
The wing had a small amount of wash-in on the left side, about 1/2 way out.
The combination made the thing nearly unflyable on the first flight. It couldn't turn left without snapping to the left, which made landing extremely difficult.
Adding the nose weight, mounting a -new- wing which the newbie had with him, and on the second flight I had him flying the thing around.
It's not a bad flier. Takes off poorly though.
The third flight he took off and flew around without anything but verbal assistance.

Actually, different airfoils stall at different AOAs. The AOA is dependent on the airfoil. The symmetrical Eppler 168 stalls at roughly 8degrees according to the theoretische polaren chart in Eppler's book MTB1. E474 appears to stall in the same Reynolds number range at more than 10degrees.

One reason might be that when airfoils stall, they don't suddenly lose lift, but they do suddenly gain a LOT more drag. At the stall, the increase in drag often has more effect than the decrease in lift that continues with further increases in AOA.

Actually, induced drag is created at all speeds if the airfoil is not at the AOA at which that airfoil produces zero lift. If there is lift created, there is induced drag created. And the amount of induced drag is related to the lift being produced. And air spills over the wing tips at all speeds that our models fly. It may or may not spill more at different speeds. But it is induced in relation to the amount of lift being created.

I'm sure that I simply misunderstood what you were saying, but felt the need to mention a couple of points.

That's OK. I thought I was clear, but obviously not enough. I hope I haven't confused the quoting here..

Thanks for clearing it up. Aerodynamics is really hard to discuss.

And the correct answer to the original question is----------------------------------

Washout, is a SMALL insurance policy issued by a plane designer, to a pilot who can not fly the plane correctly.


Next question.

Negative, it is a way to improve low speed performance, thus allowing for shorter landing distances.

Bart

barto,
I think cyclops2 was simply being humorous. At least I laughed when I read it.

(Is it a full moon?)

Well, couldn't really see the humor... spitfire - washout - pilot not flying the plane correctly...

it just was full moon I think, ah well maybe it's because the days are getting shorter

grtz
Bart

It was ment as a humorous way of saying, do not try to fly the plane so slow, that you need those few slower mph.

Land faster and warm up the brakes.

Just for fun...In theory an eliptical wing (ie like a Spitfire) stalls at the same time along its entire length but I suppose the Spitfire wing is not a perfect elipse thus the need for washout?
Also, lift/drag are effects not causes. I think a wing stalls at a specific AOA due to delamination of the airflow resulting in drag/loss of lift. True?
My experience is washout helps and scale washout is probably not aerodynamically ideal on a model but still helps.

PS. probably should have read this thread first before posting my dumb "Flaps and tip stall question".
Late night brain fade![:-]

I have been following thid thread, mostly out of curiosity, and what follows is not intended to add anything, just FYI.
Spitfires with the original wing, ie up to Mk21's, all had washout, jig built in over the full half span, the wing tips were just a bolt on item depending on the intended mark. This `washout' was 2.5 deg. Spitfire pilots were always very appreciative of the aircraft's stall characteristics, as a really tight fully accelerated turn would shake off most opposing aircraft. I think the only a/c with a better turn was the Hurricane. FW 190's had 3.0 deg washout, 109's didn't have any, didn't need it because they used auto slats to do the same thing. As for flaps, it depends what you want to do. Spit. flaps were only drag devices, either up or 90 deg. down for glidepath control. FW190's had two positions, `lift' about 12 deg down and `Land' around 75 deg down, again just for drag. Early 109's had full camber changing devices, even the ailerons drooped at full flap. P47's had `proper' Fowler `extend and droop' things for camber control because they needed them, without flaps it wouldn't leave the ground, and couldn't slow down enough to land. IMHO small pointy wing tips need washout, wide straight ones don't. Models only need flaps when they start to get a bit heavy and big and need camber/drag control to get into typical model strips. More moving bits equals more weight, better to build lighter than add complexity and weight.

Does the new Hangar 9 Spitfire have washout?