Spitfire short take-offs?

Just a small sidelight that I’ve remembered…

The Spitfires flaps were either fully down or fully up, so not much use for take off. However, for a shortened take off aboard a carrier relieving Malta (USS Wasp? Mk.Vs?) small wooden wedges were inserted to give a partial flap setting (45 deg?) which helped shorten the take off. Oh, and steaming into wind, of course… Once in the air, full flap was selected, the wedges dropped out and then the flaps selected and retuned to ‘up’.

The story of the recovery of several sets of these wedges, and avaliability at Shoreham via Von P is an exaggeration however… 😀

It is Clostermann, after all.

Manu Geerts first Tiffy flight with 609 was supposed to be somewhat special…

Amazing what the RAF’s aviators turn their attention to when the politicians can’t find them a war to keeping them busy. 😀

Short Take-offs…

After researching RAF Lichfield I was intrigued to hear that a whole bunch of bored pilots (fighter and bomber) were hanging around trying to think of things to keep them busy. High on their list were

How quickly can we get a Lancaster into the air?

and

Can we take a spitfire off from inside a hangar?

The answer to this latter question was yes!! They opened the hangar doors and managed to get the spitfire off the ground along the short taxi way and in the air. Unfortunately I do not have any figures as I think this may have been a slightly unauthorised activity!!

As another note there was one pilot who was barred from ever flying over Lichfield by the RAF top brass as he flew a Mosquito on its wingtips ‘through the spires of the cathedral’!!

Could this be some misunderstanding?

As I have read in a Spitfire book once that (with a stiff wind) a Mk IX Spit could get it’s tail off the ground withing fifty yards. With all the power and weight of the cannon it wouldn’t surprise me.

Cheers

Cees

Very intriguing! Thanks

The short answer is “possibly, if it’s windy”. Theory is not much use over such a short distance as so much depends on technique and small variations in the assumptions can have big effects. But it’s quite fun to see what the published data reveal and play with the figures to see what’s plausible. We need to know the speed that the aircraft needs to accelerate to, the acceleration available, and we can work out the space needed.

I don’t have an authoritative stall speed report on the IX in combat trim to hand, but I did find a copy of the A&AEE handling report on the 4x20mm equipped Vc here,
http://www.fourthfightergroup.com/eagles/aa873.html , which quotes a clean, presumably power-off stall of 81mph with heavy buffeting from 90 mph. The AUW is not quoted, alas.

http://www.fourthfightergroup.com/eagles/bf274.html is the A&AEE speed performance report for the IX, Sadly it does not quote stalling speeds but gives an AUW in military trim of 7480 lb with full internal fuel, no overload tank.

It seems reasonable to assume that the extra weight and drag of the two additional cannons on the Vc tested above would be compensated for in the IX by the extra engine weight of the 60 series engine, the four blade prop, and the wing machine guns (whether they be 2x .50 or 4 x .303). So I doubt the IX is operating at a lighter weight than the Vc tested here.

Stall speed at full power would be considerably lower than power-off, especially with a big 4-blade prop in fine pitch either “blowing” the wing roots or partially blanking them, but no sane pilot would pull off an aeroplane in heavy buffet, even if it has the gentle stall of a Spitfire. Factor all that in and let’s work with 80 mph as the lowest unstick speed we might imagine, letting the aeroplane rise by itself from the three-point attitude as one might if really struggling for the lowest unstick speed.

A 360hp Yak with a really efficient 3 blade c/s prop has static thrust of about 1,350 lb. A Spit with a Merlin 66 has 1315 bhp at sea level using the take-off settings of 3000 rpm / +12 boost. That’s 3.65x the power, so let’s say 3.65 the static thrust: 4927lb. That means that the initial acceleration in G will be 4927 / 7480, or as near two-thirds of a G as makes no difference. (It will slacken off a bit as drag becomes a factor but let’s ignore that for now).
You need about 1.5G constant acceleration over 50 yards to get to 80mph. So it’s not a goer in still air. But 0.66G will get you to almost 55mph. With a 25mph headwind component, that’s enough. (And if you have a healthy crosswind from the right, you might even be able to get full power on right from the start of the take-off roll rather than screw the aeroplane into the ground!).
None of this as ANYTHING to do with quoted take-off distances of course, which factor in all kinds of fudge factors, safety margins, obstacle clearance etc. It also totally ignores slope or runway surface, and ground effect. With the Spit’s broad wings and low wing, ground effect undoubtedly significantly lower the minimum achievable unstick speed, though not the speed at which one may climb away…

I’m sure in the abridged version of the book which I have at home (doubtless the only version around until recently), it says 150 yards, with the poor old Thunderbolt coming unstuck after 600.

(It doesn’t say, however, whether the Spitfires are fully loaded – the Thunderbolts are)

Or a cliff.

However, apart from ‘a typo’ anyone got some useful input?

You could get a Spitfire airborne in 50 yards if you use RATO, and a few bottles of it at that! 😀

The book (neither version) doesn’t mention weather/field conditions, unfortunately 🙁

Possible, but I guess you’d need a 90 knot headwind.

Moggy