Handley-Page Slots or Handley-Page Slats ? Armstrong Whitworth Atlas

Asymmetric slat deployment could also upset gun aiming on an operational type – it might have been better if the slats had been ‘linked’ so both either ‘in’ or ‘out’ – although I realise this might have been difficult to engineer !

Funnily enough, the Whirlwind had them. Unlocked, they gave a boost to agility by deploying when the angle of attack was great enough. They got locked down flush as a safety measure once a couple of accidents had been attributed to unwanted deployment. Dr. Jim Munro’s research has suggested that some later pilots who tried out the aircraft had no idea that they even existed, and this goes some way to explain why there are two different versions of the aircraft’s potential in a dogfight (though among squadron pilots the praise was unanimous). It has been suggested that some may have been ‘de-modded’ in the field to get the slat functionality back.

Also , it might be of interest to note that the Lysander flap and slat mechanisms were inter linked. Slat out/flap down…….
Thanks Powerandpassion ….One has to be SO careful what one says these days!

All thanks I now understand how this all fits in

In H-P’s original patent (GB 157567) he uses the term slot throughout but the movable part that we now refer to as the slat he terms as a leading edge auxiliary aerofoil

The answer is that both “HP slat” and “HP slot” are correct and both terms are certainly used in textbooks and they refer to the same entity. The distinction, if one is needed, is that the slot is the aerodynamic device that can increase lift while the slat is the structural component used to achieve the slot. The Krueger slat on the other hand does not provide a slot in any form but merely modifies the leading edge of the wing by providing a downwards projection from the profile nose, again as a device to increase lift.

It was alleged many years ago that Messerschmidt paid royalties, via Switzerland, throughout WW2 to Handley-Page for use of the H.P. slat on the Me 109. I stress this was merely an allegation in circulation , probably totally without foundation of course.

Absolutely and so they should. From the late 20’s the HP slat was marketed commercially so there were longstanding arrangements in place and in this case we can say that Herr Messerschmit was a man of honour. The Fiesler Storch of course had HP slats, so Mussolini was also plucked from danger by HP innovation, but so too the Westland Lysander. HP slats were basically everywhere by 1939.

As distasteful and surprising as it appears, commercial arrangements persisted through the war, and there are many examples.

From the Handley Page Commerative publication, I think 1959, Mr Frederick HP describes his slat mechanism, which when extended, created a slot for air to flow.

An old crop duster told me that they used to lock down the slats when spreading fertilizer over the rice paddies in Australia, because the turbulent air low down could cause one slat to extend while the other stayed in place, making one wing lift and the other to drop, with consequent embarrassment.

I have spent a great deal of time poking through the remains of Hawker Australian Demon wings, which in common with the Hart family had HP slats. I was surprised to see in wing remnants a small protruding stud with stainless steel nut proud of the upper surface of the top wing which engaged with a tab on the rear of the slat to lock it in place. It seems that they were locked in place as standard practice, for the reason alluded to by the crop duster. In capable hands they assisted in the stall but in inexperienced hands and crosswinds they perhaps promoted accidents. I interpret the word ‘sealed’ as slats locked down per the Demon observation. I interpret the ‘official’ comments in respect of accidents in 1930 being based on a time in which the dangers of stall were clearly appreciated officially but the dangers of uneven slats were not yet accepted officially. Perhaps individual Squadrons, alive to a novel danger, had sealed their slats for trainees. I think the HP slat came in about 1928. It would be a very brave bureaucrat in the Air Ministry to put in writing in 1930 a condemnation of a relatively new invention that obviously saved lives but less obviously took them, at the time that FHP was probably Chair of the SBAC. Things have evolved and every time I sit over the wing of a Boeing and see the slat extend I say a little thank you to Fred, but in wind shear and the hands of a 23 year old pilot I wonder if one day it might help finish me.

It was alleged many years ago that Messerschmidt paid royalties, via Switzerland, throughout WW2 to Handley-Page for use of the H.P. slat on the Me 109. I stress this was merely an allegation in circulation , probably totally without foundation of course.

You are right: the HP slats are automatic in operation and create a slot. Confusion is understandable.