Clipped Wings

[seand]

Can anyone help,

I have been having a debate at work over the clipping of wings / the fitting of ferry tips etc on spitfires, Fury's and even on some modern aircraft.

How did or does it help the handling of the aircraft?

[Solid Rust Twotter]

Reduce chances of a tip stall (Spitfire) with those pointy wingtips?

[CarltonBrowne the FO]

AFAIK on the Spitfire, the wing-clipping was done on those models intended (or modified) for low-level; the slight increase in induced drag (due to increased spanwise flow) being considered acceptable, in order to gain a slight improvement in roll rate.
I've never heard of tip stall being a problem with the original wingtips, but stand ready to be corrected; however, I remember my Aerodynamics lecturer explaining that an elliptical wing planform is the most efficient (gives the best Lift/Drag ratio) at low subsonic speeds. In practice I suspect that at low-level, increased roll rate is worth a slight loss of pitch rate.

[Skylark4]

One of the crazy ideas that was trialled was the fitting of a complete second wing to make the Spit a biplane. It was intended for heavy takeoffs and was, I think, intended to be jettisoned in flight. Seen a picture in a book somewhere but I've read a lot of books.

Mike W

[henry crun]

Skylark4: I have read of a biplane version of the Hurricane, but never a Spitfire.

[dmanton300]

I think, as far as the spit goes, we're taslking about the "Clipped, Cropped and Clapped" V's. THey had the wings clipped for better roll rate at low altitude, the supercharger was cropped to tune for low altitude and the airframes that underwent this surgery were clapped out old wringers.

The twin wing fighter was a Hurricane, known as the "slip-wing".

[izod tester]

The Mk XVI was also a clipped wing variant, so not necessarily "clipped, cropped and clapped".

What was the effect on handling of the extended wing fitted to the Mks VI and VII for high altitude performance?

[teeteringhead]

The twin wing fighter was a Hurricane, known as the "slip-wing". ..and also designed to shorten take-off run for carrier operations IIRC?

At least that's what "Battler" Brittan (or was it "Rockfist" Rogan) used it for in the "Wizard".

But he (whichever it was) also managed on one occasion to jettison the top wing into the path of a pursuing Me 109, much to the surprise of "Fritz"! (But he wasn't allowed to claim it, as he had expended no ammunition.)

[DK338]

The clipping of Spitfire wings was instigated in 1941 on the MkV to counter the FW190. At that time the main protagonists in the air war over europe were the BF109F and the Spit MkV.

The Hurricane was evolving more into a ground attack variant with the introduction of the 12 gun IIB 'Hurribomber' and the 4x 20mm Hispano cannon armed IIC and with the later IID would see meningi service in North Africa, Russia and the Far East.
The Hillison Slip Wing Hurricane was a barking experiment to try and shorten the take of run of a Hurricane, and although successful was never introduced into service as the requirement for it went away(or more likely somebody woke up!). Other looney ideas for the poor old Hurri was to be towed behind Wellingtons on Germany bombing raids, the idea being that at the merest sniff of trouble they would start engines, release and engage. Bit like an airborne version of the CAM ship concept. Clearly there was confidence that the aircraft would have sufficient fuel to make it back to blighty after combat.

Returning to the Spit, the FW190 came as a bit of a shock. Small, heavily armed and dynamic with heaven forbid, a radial engine of all things. After much scratching of heads it was decided to remove the wing tips of the Spit Vb in an attempt to increase the rate of roll to counter the manoeuvreability of the 190. It worked, but at low level, which at the time was where the RAF was operating mainly in 1941/42 with it's Rhubarbs, Balbo's et al over enemy occupied europe. However this fix was purely a temporary measure and Joe Smith at VS was tasked with coming up with something more effective for the long term.

At the time VS were developing the MkVIII, Merlin 60 series twin supercharger, 2x 20mm Hispano and 4 Browning 303, broad chord rudder, retractable tailwheel and so on which was based on a MkVc airframe with strengthened longerons to cope with the bigger engine and was intended for the Desert and Far East. To save time VS bunged the Merlin 60 series into a MkVc airframe with strengthened bits but left out the gucci add ons like the broader rudder and retractable tailwheel and called it the MkIX. This variant ironically became the most produced of all versions of the Spitfire. From here the MkIX followed the 2 tier protocol developed for the MkVb and Vc, low level (LF), high level (HF) and the differences being LF aircraft were clipped with no supercharger while the HF variant was the standard 36' 10'' wingspan with a fully functioning twin supercharger. Remember the MkV was fitted with a Merlin 45 which was non supercharged equipped but the engines were tweaked to operate better in their intended environment.

The term 'Clipped, Clapped and Cropped' certainly did not apply to the MkIX onwards but anecdote has it that it was an affectionate term applied to the modified MkV's only, but clearly the term has stuck.

Other varients to be graced with a clipped wing were the MkXII (41 Sqn only), XIV, XVI and XVIII. From the Mk 21 onwards the wing was a total redisign, bit similar to the Hawker Tempest in profile.

Hope this helps and I really must get out more!

[keithl]

Rockfist Rogan was the "Tiger". Battler Brittain must have been the "Wizard"

[dmanton300]

Sorry, I should have been clearer. . I was of course only referring to the Mk V's in this context. I'm well aware that many IX/XVI had clipped wings, as did numerous XIVe models and all the production XII's. Unsure about MkVIII?

[DK338]

Some MkVIIIs had clipped wings too, if I recall correctly only in the mediterranean theatre though.

The fitting of ferry tanks on Spits started with an experiment in early 1941 on a MkII. The tank was fitted to the wing inboard of one wingtip enveloping the leading edge and protruding forward. I can't remember which tip it was fitted to but it was the opposite to the way the prop span, the idea being that the gyroscopic forces of the engine torque would counteract the weight of the tank. The concept was a failure as the aircraft unsurprisingly had some pretty undesirable handling problems.

Later the slipper tank was developed and was a huge success enabling the Spit to be ferried over great distances. The reinforcement of Malta being a good example where the slipper tank was put to good use. Later still internal fuselage tanks were fitted behind the pilot.

[teeteringhead]

Other looney ideas for the poor old Hurri was to be towed behind Wellingtons but you don't need to tow aircraft.....

.....if you've got Battler Britton! (http://www.bookpalace.com/PicLibs/TPL/pages/TPL329.htm)

[sycamore]

DK338,just a note to correct your earlier statement about `cropped` superchargers. All Spitfires were supercharged to a greater or lesser degree, later ones with 2-speed 2 stage. Where the term `cropped` is mis-used is in ref to low-level variants such as the Vc.The supercharger impeller was reduced in diameter which only changes the `full-throttle height` of the aircraft, ie reduced from perhaps 25000` to 15000`, optimising it for lower level ops. Indeed the Mk Vc with a Merlin45M fitted was allowed to push +18lbs(+66") of boost for 5 minutes in combat, +12lbs for T/O. Cropped engines, usually 45M,50M, and 55M,the `M` suffix denoted `cropped`, usually were +2lbs boost better off .Later engines with the 2speed 2stage superchargers were much better placed.

[seand]

Thank you for your help, which solved the main question but also brought on a few new questions (ie why put different wing tips on for ferry flights or different stores).


Interesting that the Slip-Wing Hurricane was brought up, I remember coming across some old photos at work in the eighties (at Kingston), I’ve had a check through Putnam – Hawker Aircraft and they quote the aircraft as being a one off aircraft (L1884), which was modified by Hill and Sons and known as F.H.40, the idea was to provide extra lift for take-off.

[ZH875]

A model of Slip Wing Hurricane:
http://img.photobucket.com/albums/v604/ZH875/Slip-wing20Hurricane20FrontLHS_Davies.jpg

[TD&H]

DK338:

Mk XVIII's were all full span, maybe your earlier reference to them should have read VIII. XVIII were all post war.

Seand:

IIRC all XII were clipped, with a hastily inserted single stage Griffon, again a FW190 chaser, low level. Most XVI were produced as clipped tips. The Packard Merlin having a supercharging more ideal for lower level work. Some IX's were clipped. Some XIV's were also clipped.

Again IIRC the most produced mark was the V, in all its variants. Some were reworked into IXs.

The IX was an interim measure before full production of the VIII, which was designed to have all the extras. Retractable tailwheel, increased rudder to counter the increasing power of the two-stage, two-speed 60 series Merlins, increased fuel with a small tank in each wing. However it took so long to get all the mods in to production that it was well beaten by the IX for production numbers. Often the VIII's were sent out to the middle and far east, the mods being thought more appropriate for the work out there.

The XIV was again an interim model before full production of the XVIII, which had a solid spar, as against the built up box spar. But like the IX and VIII, the XIV was produced in much greater numbers than the XVIII, and saw service in WWII, whereas the XVIII only saw action in Middle and Far East, post war. But had the distinction of being the last Spitfire in RAF service to fire its guns at the Kings enemies.

The long span VI and VII gave improved lift for the very high altitude planned for their operations. There's one in the Air and Space museum (US), they do look strange.

Indeed the first mod's to clip the wings were reputed to be done in the squadrons.

If you really wish to know the story of the Spitfire, then read Jeffrey Quill's book, good detail of all the main marks and variants with the reasoning behind them.

[DK338]

Sycamore and TD&H,

Thanks guys for your expansion on the technical elements of this fascinating topic. And you are quite correct I should have said MkVIII vice XVIII.

DK